Community-Acquired Pneumonia (CAP)-Part 1


Epidemiology

Prevalence

CDC Etiology of Pneumonia in the Community (EPIC) Study of Community-Acquired Pneumonia (CAP) Requiring Hospitalization in the US (NEJM, 2015) [MEDLINE]

  • Incidence
    • Annual Community-Acquired Pneumonia Incidence was 24.8 Cases Per 10k Adults
    • Highest Community-Acquired Pneumonia Rates were Observed Among the 65-79 y/o Age Group (63.0 Cases Per 10k Adults) and Among the ≥80 y/o Age Group (164.3 Cases Per 10k Adults)
    • Community-Acquired Pneumonia Incidence Increased with Age for All of the Pathogens
  • Median Age of Community-Acquired Pneumonia Patients was 57 y/o
  • Pathogen Identification and Distribution
    • A Community-Acquired Pneumonia Pathogen was Detected in Only 38% of Cases
      • One or More Viruses: 23% of cases
      • Bacteria: 11% of cases
      • Bacterial and Viral Pathogens: 3% of cases
      • Fungal or Mycobacterial Pathogen: 1% of cases
    • Approximately 5% of Cases Had Co-Detected Pathogens (i.e More Than One Pathogen Detected)
    • Incidence of Community-Acquired Pneumonia Pathogens (In Descending Order of Incidence)
  • Environment of Care and Prognosis
    • Approximately 21% of Community-Acquired Pneumonia Cases Required ICU Care
    • Overall Mortality Rate was 2%

Predisposing Factors/Epidemiologic Factors Associated with Various Infectious Etiologies of Community-Acquired Pneumonia (Clin Infect Dis, 2007) [MEDLINE]

Advanced Age

  • General Risk
    • Systematic Review of Risk Factors for Community-Acquired Pneumonia in Ambulatory/Hospitalized Adults (Respiration, 2017) [MEDLINE]: n = 29 (20 case-control, 8 cohort, and 1 cross-sectional) with median Newcastle-Ottawa scale score of 7.44 (range 5-9)
      • Factors Associated with an Increased Risk of Community-Acquired Pneumonia
      • Factors Not Associated with an Increased Risk of Community-Acquired Pneumonia

Alcohol Abuse (see Ethanol)

Aspiration

  • Specific Organisms

Asthma (see Asthma)

Bioterrorism

  • Specific Organisms
    • Bacillus Anthracis (Anthrax) (see Anthrax)
    • Francisella Tularensis (Tularemia) (see Tularemia)
    • Yersinia Pestis (Plague) (see Plague)

Chronic Kidney Disease (CKD) (see Chronic Kidney Disease)

  • Specific Organisms
    • Staphylococcus Aureus (see Staphylococcus Aureus)
      • In a Retrospective Study Including Both Community-Acquired and Hospital-Acquired Bacteremic Staphylococcus Aureus Pneumonia, Chronic Kidney Disease was Associated in 31.6% of Cases (Eur J Clin Microbiol Infect Dis, 2016) [MEDLINE]

Chronic Obstructive Pulmonary Disease (COPD) (see Chronic Obstructive Pulmonary Disease)

Cirrhosis (see Cirrhosis)

  • Specific Organisms
    • Staphylococcus Aureus (see Staphylococcus Aureus)
      • Studies Suggest that Cirrhosis is Associated with an Increased Risk for Staphylococcus Aureus Pneumonia in the Hospital Setting (Pulm Med, 2016) [MEDLINE] (Chin Med J (Engl), 2019) [MEDLINE]

Congestive Heart Failure (CHF) (see Congestive Heart Failure)

  • Specific Organisms
    • Staphylococcus Aureus (see Staphylococcus Aureus)
      • In a Retrospective Study Including Both Community-Acquired and Hospital-Acquired Bacteremic Staphylococcus Aureus Pneumonia, Cardiovascular Disease was Associated in 31.6% of Cases (Eur J Clin Microbiol Infect Dis, 2016) [MEDLINE]
    • Streptococcus Pneumoniae (see Streptococcus Pneumoniae) (Thorax, 2015) [MEDLINE]

Corticosteroids (see Corticosteroids)

Cough >2 wks with Whoop or Post-Tussive Emesis

  • Specific Organisms
    • Bordetella Pertussis (Pertussis) (see Pertussis)

Diabetes Mellitus (DM) (see Diabetes Mellitus)

  • General Risk
    • Systematic Review of Risk Factors for CAP in Ambulatory/Hospitalized Adults (Respiration, 2017) [MEDLINE]: n = 29 (20 case-control, 8 cohort, and 1 cross-sectional) with median Newcastle-Ottawa scale score of 7.44 (range 5-9)
      • Factors Associated with an Increased Risk of Community-Acquired Pneumonia
        • Age
        • Asthma (see Asthma)
        • Chronic Obstructive Pulmonary Disease (COPD) (see Chronic Obstructive Pulmonary Disease)
        • Environmental Exposures
        • Functional Impairment
        • Immunosuppressive Therapy
        • Malnutrition
        • Oral Steroids
        • Poor Dental Health
        • Previous CAP
        • Tobacco Smoking (see Tobacco)
        • Treatment with Gastric Acid-Suppressive Medications
      • Factors Not Associated with an Increased Risk of Community-Acquired Pneumonia
        • Alcohol Use (see Ethanol)
        • Cancer
        • Chronic Kidney Disease (CKD) (see Chronic Kidney Disease)
        • Diabetes Mellitus (DM) (see Diabetes Mellitus)
        • Gender
        • Influenza Vaccination
        • Inhalation Therapy
        • Liver Disease (see Cirrhosis)
        • Overweight
        • Pneumococcal Vaccination
        • Recent Respiratory tract infections
        • Swallowing Disorders
    • English Retrospective Cohort Study of Primary Care Patients with/without Type 1/II Diabetes (Diabetes Care, 2018) [MEDLINE]: 102,493 primary care patients (age 40-89 y/o)
      • Risk of Pneumonia (Type I DM): Incidence Rate Ratio 2.98 (95% CI: 2.40–3.69)
      • Risk of Pneumonia (Type II DM): Incidence Rate Ratio 1.58 (95% CI: 1.53–1.64)
    • South Korean National Chort Study (Diabetes Metab J, 2019) [MEDLINE]: n = 66,426 diabetics and 132,852 age/sex/region-matched non-diabetic controls
      • Diabetics Had an Increased Risk of Respiratory Infection (Adjusted Incidence Ratio 1.76; 95% CI: 1.72–1.81)
      • Diabetics Had an Increased Risk of Pneumonia (Adjusted Incidence Ratio Ratio 1.57; 95% CI, 1.52-1.62)
    • Spanish Study of Community-Acquired Pneumonia in Primary Care (BMC Infect Dis, 2019) [MEDLINE]: n = 51,185
      • Approximately 16% of Community-Acquired Pneumonia Patients in the Primary Care Setting Had Diabetes as Comorbidity
  • Specific Organisms
    • Staphylococcus Aureus (see Staphylococcus Aureus)
      • Study of Risk Scoring System to Identify Patients with MRSA Admitted with CAP (BMC Infect Dis, 2013) [MEDLINE]: n = 5975
        • Risk Factors Included Recent Hospitalization or ICU Admission (2 pts), Female Sex with Diabetes (1 pt), Age <30 or >79 (1 pt), Prior Antibiotic Exposure (1 pt), Dementia (1 pt), Cerebrovascular Disease (1 pt), Recent Exposure to a Nursing Home/Long-Term Acute Care Facility/Skilled Nursing Facility (1 pt)
        • Prevalence of MRSA Increased with Increasing Score: Low Risk (0 to 1 pts), Medium Risk (2-5 pts) and High Risk (≥6 pts)
      • In a Retrospective Study Including Both Community-Acquired and Hospital-Acquired Bacteremic Staphylococcus Aureus Pneumonia, Diabetes Mellitus was Associated in 29.6% of Cases (Eur J Clin Microbiol Infect Dis, 2016) [MEDLINE]
      • Studies Suggest that Diabetes Mellitus is Associated with an Increased Risk for Staphylococcus Aureus Pneumonia in the Hospital Setting (Pulm Med, 2016) [MEDLINE] (Chin Med J-Engl, 2019) [MEDLINE]
    • Streptococcus Pneumoniae (see Streptococcus Pneumoniae)
      • Diabetes Mellitus Increases the Risk of Pneumococcal Disease (Thorax, 2015) [MEDLINE]
  • Protective Effects of Specific Treatment Regimens for Diabetes Mellitus
    • Patients with Type 2 Diabetes Taking Sodium-Glucose Cotransporter-2 (SGLT2) Inhibitors are at Decreased Risk for Pneumonia and Sepsis, as Compared to Those Taking Dipeptidyl Peptidase-4 (DPP-4) Inhibitors (Diabetes Metab, 2022) [MEDLINE] (see Sodium-Glucose Cotransporter-2 Inhibitors and Dipeptidyl Peptidase-4 Inhibitors)
    • In VA Retrospective Cohort Studies (n = 34,759), Patients with Diabetes Taking Metformin and Who are Hospitalized with Pneumonia were Demonstrated to Be at Decreased Risk of Mortality (Clin Infect Dis, 2022) [MEDLINE] (see Metformin)
      • Unadjusted 30-Day Mortality was 9.6% for Patients Who Had Received Metformin vs 13.9% in Patients Who Had Not Received Metformin (P < 0.003)
      • Unadjusted 90-Day Mortality was 15.8% for Patients Who Had Received Metformin vs 23.0% for Patients Who Had Not Received Metformin (P < 0.0001)
      • After Propensity Matching, Both 30-day (Relative Risk 0.86; 95% CI 0.78-0.95) and 90-Day (Relative Risk 0.85; 95% CI: 0.79-0.92) Mortality was Significantly Lower for Metformin Users

Endobronchial Obstruction

Exposure to Bat/Bird Droppings

  • Specific Organisms

Exposure to Birds

Exposure to Farm Animals/Parturient Cats

  • Specific Organisms
    • Q Fever (Coxiella Burnetii) (see Q Fever)

Exposure to Guinea Pigs

Exposure to Rabbits

  • Specific Organisms
    • Francisella Tularensis (Tularemia) (see Tularemia)

Exposure to Invasive Mechanical Ventilation (see Invasive Mechanical Ventilation-General)

Human Immunodeficiency Virus (HIV) (see Human Immunodeficiency Virus)

Influenza Active in Community

Injection Drug Abuse (see Injection Drug Abuse)

Lung Abscess (see Lung Abscess)

Organ Failure

Structural Lung Disease (Bronchiectasis, etc)

Tobacco Abuse (see Tobacco)

  • General Risk
    • Systematic Review of Risk Factors for CAP in Ambulatory/Hospitalized Adults (Respiration, 2017) [MEDLINE]: n = 29 (20 case-control, 8 cohort, and 1 cross-sectional) with median Newcastle-Ottawa scale score of 7.44 (range 5-9)
      • Factors Associated with an Increased Risk of Community-Acquired Pneumonia
        • Age
        • Asthma (see Asthma)
        • Chronic Obstructive Pulmonary Disease (COPD) (se eChronic Obstructive Pulmonary Disease)
        • Environmental Exposures
        • Functional Impairment
        • Immunosuppressive Therapy
        • Malnutrition
        • Oral Steroids
        • Poor Dental Health
        • Previous Community-Acquired Pneumonia
        • Tobacco Smoking (see Tobacco)
        • Treatment with Gastric Acid-Suppressive Medications
      • Factors Not Associated with an Increased Risk of Community-Acquired Pneumonia
        • Alcohol Use (see Ethanol)
        • Cancer
        • Chronic Kidney Disease (CKD) (see Chronic Kidney Disease)
        • Diabetes Mellitus (DM) (see Diabetes Mellitus)
        • Gender
        • Influenza Vaccination
        • Inhalation Therapy
        • Liver Disease (see Cirrhosis)
        • Overweight
        • Pneumococcal Vaccination
        • Recent Respiratory tract infections
        • Swallowing Disorders
    • Systematic Review and Meta-Analysis of the Effect of Tobacco Smoking on the Risk of Developing Community-Acquired Pneumonia (PLoS One, 2019) [MEDLINE]: n = 27 studies
      • Current Smokers (Pooled OR 2.17, 95% CI: 1.70-2.76, n = 13 Studies; Pooled HR 1.52, 95% CI: 1.13-2.04, n = 7 Studies) and Ex-Smokers (Pooled OR 1.49, 95% CI: 1.26-1.75, n = 8 Studies; Pooled HR 1.18, 95% CI: 0.91-1.52, n = 6 Studies) Had an Increased Risk of Developing CAP, as Compared to Never Smokers
      • Dose-Response Analyses of Data from 5 Studies Indicated a Significant Trend, Such that Current Smokers Who Smoked a Higher Amount of Tobacco Had a Higher CAP Risk
      • Although the Association Between Passive Smoking and Risk of CAP in Adults of All Ages was Not Statistically Significant (Pooled OR 1.13, 95% CI: 0.94-1.36, n = 5 Studies), Passive Smoking in Adults ≥65 y/o was Associated with a 64% Increased CAP Risk (Pooled OR 1.64; 95% CI: 1.17-2.30, n = 2 Studies)
  • Specific Organisms

Travel to Hotel or on Cruise Ship Stay within 2 wks

Travel to Middle East within 2 wks

Travel to or Residence in Southeast and East Asia

Travel to or Residence in Southwestern United States

Water Colonization


Microbiology

General

Study of the Most Common Etiologies of Community-Acquired Pneumonia (CAP) (Clin Infect Dis, 2007) [MEDLINE]

CDC Etiology of Pneumonia in the Community (EPIC) Study of Community-Acquired Pneumonia (CAP) Requiring Hospitalization in the US (NEJM, 2015) [MEDLINE]

Viral

Bacterial

Fungal

Parasitic

  • Echinococcosis (see Echinococcosis)
    • Etiology
      • Echinococcus
  • Paragonimiasis (see Paragonimiasis)
    • Etiology
      • Paragonimus Westermani and Other Paragonimus Species
  • Strongyloidiasis (see Strongyloidiasis)
    • Etiology
      • Strongyloides


Diagnosis

General Comments Regarding Diagnostic Testing for Patients with Community-Acquired Pneumonia (CAP)

Recommendations (American Thoracic Society and Infectious Diseases Society of America 2007 Consensus Guidelines on the Management of Community-Acquired Pneumonia in Adults) (Clin Infect Dis, 2007) [MEDLINE]

  • Patients with Community-Acquired Pneumonia Should Undergo Diagnostic Testing to Detect Specific Suspected Pathogens that Would Significantly Alter the Choice of Empiric Antibiotic Therapy (Strong Recommendation, Level II Evidence)
  • Routine Diagnostic Testing to Identify an Etiologic Organism in Outpatients with Community-Acquired Pneumonia is Optional (Moderate Recommendation, Level III Evidence)

Erythrocyte Sedimentation Rate (ESR) (see Erythrocyte Sedimentation Rate)

Clinical Efficacy

  • Dutch Cross-Sectional Study of Symptoms, Signs, Erythrocyte Sedimentation Rate, C-Reactive Protein in the Diagnosis of Pneumonia by Outpatient General Practitioners (Br J Gen Pract, 2003) [MEDLINE]: n= 246 presenting with lower respiratory tract infection
    • Dry Cough, Diarrhea, and T >38 Degrees C were Statistically Significant Predictors of Pneumonia
    • Pulmonary Auscultation and Clinical Diagnosis of Pneumonia by the General Practitioner were Not Statistically Significant Predictors of Pneumonia
    • Erythrocyte Sedimentation Rate and C-Reactive Protein Had Higher Diagnostic Odds Ratios than Any of the Symptoms
    • Adding C-Reactive Protein to the Final Symptoms and Signs Model Significantly Increase the Probability of Correct Diagnosis
    • Applying a Prediction Rule for Low-Risk Patients (Including a C-Reactive Protein <20 mg/dL), 80 of the 193 Antibiotic Prescriptions Could Have Been Prevented with a Maximum Risk of 2.5% of Missing a Pneumonia Case

C-Reactive Protein (CRP) (see C-Reactive Protein)

Clinical Efficacy

  • Dutch Cross-Sectional Study of Symptoms, Signs, Erythrocyte Sedimentation Rate, C-Reactive Protein in the Diagnosis of Pneumonia by Outpatient General Practitioners (Br J Gen Pract, 2003) [MEDLINE]: n= 246 presenting with lower respiratory tract infection
    • Dry Cough, Diarrhea, and T >38 Degrees C were Statistically Significant Predictors of Pneumonia
    • Pulmonary Auscultation and Clinical Diagnosis of Pneumonia by the General Practitioner were Not Statistically Significant Predictors of Pneumonia
    • Erythrocyte Sedimentation Rate and C-Reactive Protein Had Higher Diagnostic Odds Ratios than Any of the Symptoms
    • Adding C-Reactive Protein to the Final Symptoms and Signs Model Significantly Increase the Probability of Correct Diagnosis
    • Applying a Prediction Rule for Low-Risk Patients (Including a C-Reactive Protein <20 mg/dL), 80 of the 193 Antibiotic Prescriptions Could Have Been Prevented with a Maximum Risk og 2.5% of Missing a Pneumonia Case

Serum Procalcitonin (see Serum Procalcitonin)

Rationale

  • Serum Procalcitonin is the Peptide Precursor of Calcitonin Which is Released by Parenchymal Cells in Response to Bacterial Toxins
    • Serum Procalcitonin is Elevated in Bacterial Infections
    • Serum Procalcitonin is Downregulated in Viral Infections

Clinical Efficacy

  • Cochrane Database Systematic Review and Meta-Analysis of Using Serum Procalcitonin to Start or Stop Antibiotics in Acute Respiratory Tract Infection (Cochrane Database Syst Rev, 2017) [MEDLINE]
    • Use of Serum Procalcitonin to Guide Initiation and Duration of Antibiotics Results in Lower Risks of Mortality, Lower Antibiotic Consumption, and Lower Risk of Antibiotic-Associated Adverse Effects
    • Results were Similar for Different Clinical Settings and Types of Acute Respiratory Tract Infections
    • Future Research is Required to Confirm the Results in Immunocompromised Patients and Patients with Non-Respiratory Infections
  • Prospective Multicenter Study of the Ability of Serum Procalcitonin to Differentiate Viral vs Bacterial Pneumonia at Hospital Admission (Clin Infect Dis, 2017) [MEDLINE]: n = 1,735
    • Median Procalcitonin Concentration was Lower with Viral Pathogens (0.09 ng/mL; Interquartile Range <0.05-0.54 ng/mL) than Atypical Bacteria (0.20 ng/mL; Interquartile Range <0.05-0.87 ng/mL; P = 0.05), and Typical Bacteria (2.5 ng/mL; IQR, 0.29-12.2 ng/mL; P < 0.01)
    • Procalcitonin Discriminated Bacterial Pathogens, Including Typical and Atypical Bacteria, from Viral Pathogens with an Area Under the Receiver Operating Characteristic Curve of 0.73 (95% CI: 0.69-0.77)
    • A Procalcitonin Threshold of 0.1 ng/mL Resulted in 80.9% (95% CI, 75.3%-85.7%) Sensitivity and 51.6% (95% CI, 46.6%-56.5%) Specificity for Identification of Any Bacterial Pathogen
    • Procalcitonin Discriminated Between Typical Bacteria and the Combined Group of Viruses and Atypical Bacteria with an Area under the Receiver Operating Characteristic Curve of 0.79 (95% CI: 0.75-0.82)
    • In Conclusion, No Procalcitonin Threshold Perfectly Discriminated Between Viral and Bacterial Pathogens, But Higher Procalcitonin Strongly Correlated with Increased Probability of Bacterial Pathogens (Particularly Typical Bacteria)
  • Meta-Analysis of Serum Procalcitonin in Acute Respiratory Tract Infection (Lancet Infect Dis, 2018) [MEDLINE] (Lancet Infect Dis, 2018) [MEDLINE]
    • Reported Sensitivity of Serum Procalcitonin to Detect Bacterial Infection Ranges from 38-91%, Underscoring that This Test Alone Cannot Be Used to Justify Withholding Antibiotics from Patients with Community-Acquired Pneumonia
  • ProACT Trial of Procalcitonin Use for Suspected Lower Respiratory Tract Infection (NEJM, 2018) [MEDLINE]: n = 1656
    • The Provision of Procalcitonin Assay Results, Along with Instructions on Their Interpretation, to Emergency Department and Hospital-Based Clinicians Did Not Result in Less Use of Antibiotics Than Did Usual Care Among Patients with Suspected Lower Respiratory Tract Infection

Recommendations (American Thoracic Society and Infectious Diseases Society of America 2019 Clinical Practice Guidelines for the Diagnosis and Treatment of Adults with Community-Acquired Pneumonia) (Am J Respir Crit Care Med, 2019) [MEDLINE]

  • Empiric Antibiotic Therapy Should Be Initiated in Adults with Clinically Suspected and Radiographically Confirmed Community-Acquired Pneumonia, Regardless of Initial Serum Procalcitonin Level (Strong Recommendation, Moderate Quality of Evidence)

Chest X-Ray (CXR) (see Chest X-Ray)

Radiographic Findings

Clinical Efficacy

  • Army Medical Center Emergency Department Study of the Diehr Rule for the Prediction of Pneumonia in Patients Presenting with Acute Cough (J Chronic Dis, 1984) [MEDLINE]: n = 1,819
    • Pneumonia was Radiographically Diagnosed in 2.6% of the Patients
    • Clinical Decision Rule (Validated in 483 Patients)
      • Rhinorrhea: -2 point
      • Sore Throat: -1 point
      • Night Sweats/Myalgias/All-Day Sputum Production: 1 point
      • Respiratory Rate >25 breaths/min: 2 points
      • T >100 °F (37.8 °C)
    • Interpretation of Score
      • Score of -2 to -3 Points: likelihood of pneumonia was<1%
      • Score of 3-6 Points: likelihood of pneumonia was 27%
  • Emergency Department Study of Gennis Rule for the Diagnosis of Pneumonia (J Emerg Med, 1989) [MEDLINE]: n= 308
    • 38% of the Patients Had Radiographic Pneumonia
    • Symptoms
      • No Single Symptom or Sign was Reliably Predictive of Pneumonia
      • Cough was the Most Common Symptom (Present in 86% of Cases, But was Equally Common in Patients without Pneumonia)
      • Fever was Absent in 31% of Patients with Pneumonia
      • Abnormal Lung Exam (Rales, Rhonchi, Decreased Breath Sounds, Wheezes, Altered Fremitus, Egophony, Dullness to Percussion) were Found in <50% of the Patients with Pneumonia and 22% of Patients with a Completely Normal Lung Exam Had Pneumonia
    • Rule Criteria for Obtaining a Chest X-Ray, Based on Presence of At Least One of the Following (97% Sensitivity)
      • Temperature >100 °F (37.8 °C)
      • Heart Rate >100 beats/min
      • Respiratory Rate >20 breaths/min
  • Emergency Department Prospective Observational Study of Singal Rule for the Diagnosis of Pneumonia (Ann Emerg Med, 1989) [MEDLINE]: n = 255 adults
    • 15.6% of Adult Patients Had Radiographic Pneumonia
    • Univariate Predictors of Pneumonia were Fever, Cough, Crackles
      • In Absence of Fever, Cough, and Crackles, Incidence of Pneumonia was Only 4.3%
  • Emergency Department Study of the Heckerling Rule for the Diagnosis of Pneumonia (Ann Intern Med, 1990) [MEDLINE]: n= 1,436 (3 different emergency departments)
    • Rule was Developed in 1,134 Patients and Validated in 302 Patients
    • Rule Criteria for Obtaining a Chest X-Ray (from Stepwise Logistic Regression Model; p <0.001)
      • Temperature >100 °F (37.8 °C): 1 point
      • Heart Rate >100 beats/min: 1 point
      • Crackles: 1 point
      • Decreased Breath Sounds (Locally): 1 point
      • Absence of Asthma: 1 point
    • Interpretation of Score (Pre-Test Probability was 5% in Primary Care and 15% in Emergency Department)
      • Score 0
        • Post-Test Probability of Pneumonia (Primary Care): 1%
        • Post-Test Probability of Pneumonia (Emergency Department): 2%
        • Likelihood Ratio: 0.12
      • Score 1
        • Post-Test Probability of Pneumonia (Primary Care): 1%
        • Post-Test Probability of Pneumonia (Emergency Department): 3%
        • Likelihood Ratio: 0.2
      • Score 2
        • Post-Test Probability of Pneumonia (Primary Care): 4%
        • Post-Test Probability of Pneumonia (Emergency Department): 11%
        • Likelihood Ratio: 0.7
      • Score 3
        • Post-Test Probability of Pneumonia (Primary Care): 8%
        • Post-Test Probability of Pneumonia (Emergency Department): 22%
        • Likelihood Ratio: 1.6
      • Score 4
        • Post-Test Probability of Pneumonia (Primary Care): 27%
        • Post-Test Probability of Pneumonia (Emergency Department): 56%
        • Likelihood Ratio: 7.2
      • Score 5
        • Post-Test Probability of Pneumonia (Primary Care): 47%
        • Post-Test Probability of Pneumonia (Emergency Department): 75%
        • Likelihood Ratio: 17
    • Rule Had a Receiver Operating Characteristic (ROC) Area 0.82
      • In the Validation Sets, the Rule Discriminated Pneumonia and Non-Pneumonia with ROC Areas of 0.82 and 0.76 (After Adjusting for Differences in Disease Prevalence)
  • Comparative Prospective Study of Diehr/Gennis/Heckerling/Singal Rules with Physician Judgement for the Diagnosis of Pneumonia in Emergency Department and Outpatient Settings (Ann Emerg Med, 1991) [MEDLINE]: n = 290
    • All Patients Had an Acute Cough and Fever, Hemoptysis, or Sputum Production
    • 7% of Patients Had Radiographic Pneumonia (6% in Outpatient Setting, 10% in Emergency Department)
    • Performance
      • Physician Judgement: 86% sensitivity/58% specificity
      • Diehr Rule: 67% sensitivity/67% specificity
      • Gennis Rule: 62% sensitivity/76% specificity
      • Heckerling Rule: 71% sensitivity/67% specificity
      • Singal Rule: 76% sensitivity/55% specificity

Recommendations (American Academy of Family Physicians/AAFP Point-of-Care Guidelines) (Am Fam Physician, 2007) [MEDLINE]

  • Simple Rule for Determining the Need for Chest Radiography in Patients with Acute Respiratory Illness
    • Chest Radiography Should Be Performed if Either of the Following are Present
      • Presence of One of the Following
        • T >100 °F (37.8 °C)
        • Heart Rate >100 Beats/min
        • Respiratory Rate >20 Breaths/min
      • Presence of Two of the Following
        • Absence of Asthma
        • Crackles (Rales)
        • Decreased Breath Sounds

Recommendations (American Thoracic Society and Infectious Diseases Society of America 2007 Consensus Guidelines on the Management of Community-Acquired Pneumonia in Adults) (Clin Infect Dis, 2007) [MEDLINE]

  • Demonstrable Infiltrate by Chest X-Ray or Chest CT (with/without Supporting Microbiologic Data) is Required for the Diagnosis of Pneumonia (Moderate Recommendation, Level III Evidence)

Chest Computed Tomography (Chest CT) (see Chest Computed Tomography)

Radiographic Findings

  • Alveolar and/or Interstitial Infiltrates
  • Chest CT has Higher Sensitivity for the Detection of Infiltrates than Chest X-Ray

Recommendations (American Thoracic Society and Infectious Diseases Society of America 2007 Consensus Guidelines on the Management of Community-Acquired Pneumonia in Adults) (Clin Infect Dis, 2007) [MEDLINE]

  • Demonstrable Infiltrate by Chest X-Ray or Chest CT (with/without Supporting Microbiologic Data) is Required for the Diagnosis of Pneumonia (Moderate Recommendation, Level III Evidence)

Blood Cultures (see Blood Culture)

Clinical Efficacy

  • In the Outpatient Setting, Yield of Blood Cultures in Patients with Community-Acquired Pneumonia is 2% (Am J Respir Crit Care Med, 2019) [MEDLINE]
  • In the Inpatient Setting, Yield of Blood Cultures in Patients with Community-Acquired Pneumonia is 9% (Am J Respir Crit Care Med, 2019) [MEDLINE]

Recommendations (American Thoracic Society and Infectious Diseases Society of America 2007 Consensus Guidelines on the Management of Community-Acquired Pneumonia in Adults) (Clin Infect Dis, 2007) [MEDLINE]

Recommendations (American Thoracic Society and Infectious Diseases Society of America 2019 Clinical Practice Guidelines for the Diagnosis and Treatment of Adults with Community-Acquired Pneumonia) (Am J Respir Crit Care Med, 2019) [MEDLINE]

  • In the Outpatient Setting, Blood Cultures are Not Recommended in Adults with Community-Acquired Pneumonia (Strong Recommendation, Very Low Quality of Evidence)
  • In the Inpatient Setting, Blood Cultures are Not Routinely Recommended in Adults with Community-Acquired Pneumonia (Conditional Recommendation, Very Low Quality of Evidence)
  • Indications for Blood Cultures (Any of the Following)
    • Empiric Treatment for Either Methicillin-Resistant Staphylococcus Aureus (MRSA) or Pseudomonas Aeruginosa (Strong Recommendation, Very Low Quality of Evidence)
    • Prior Infection with Methicillin-Resistant Staphylococcus Aureus (MRSA) or Pseudomonas Aeruginosa (Especially Prior Respiratory Tract Infection) (Conditional Recommendation, Very Low Quality of Evidence)
      • These are the Strongest Risk Factors for Methicillin-Resistant Staphylococcus Aureus (MRSA) or Pseudomonas Aeruginosa Community-Acquired Pneumonia
    • Prior Hospitalization or Receipt of Parenteral Antibiotics within the Last 90 Days (Conditional Recommendation, Very Low Quality of Evidence)
      • These Factors Increase the Risk of Methicillin-Resistant Staphylococcus Aureus (MRSA) or Pseudomonas Aeruginosa Community-Acquired Pneumonia
    • Severe Community-Acquired Pneumonia (Especially if the Patient is Intubated), as Defined by the Following (Strong Recommendation, Very Low Quality of Evidence)
      • General Comments
        • Validated Definition of Severe Community-Acquired Pneumonia Includes Either 1 Major Criterion or ≥3 Minor Criteria
      • Major Criteria
        • Respiratory Failure Requiring Invasive Mechanical Ventilation
        • Septic Shock Requiring Vasopressors
      • Minor Criteria
        • Altered Mental Status
        • Hypotension Requiring Aggressive Intravenous Fluid Resuscitation
        • Hypothermia (Core Temperature <36°C)
        • Leukopenia (WBC <4000 Cells/mm3)
        • Multilobar Infiltrates
        • pO2/FiO2 Ratio ≤250
        • Tachypnea (Respiratory Rate ≥30 Breaths/min)
        • Thrombocytopenia (Platelets <100k Cells/mm3)
        • Uremia (BUN ≥20 mg/dL)

Sputum Gram Stain/Culture (see Sputum Culture)

Technique

  • Specimen Source
    • Endotracheal Tube Aspirate: when patient is intubated
    • Expectorated Sputum Culture: when patient is not intubated
  • Procedures
    • Bacterial Gram Stain and Culture
    • Fungal Stain and Culture: recommended for patient with cavitary infiltrates, etc
    • Acid Fast Bacterial (AFB) Stain and Culture: recommended for patient with cavitary infiltrates, etc

Clinical Efficacy

  • In Patients with Community-Acquired Pneumonia Who Have Been Newly Intubated, Endotracheal Aspirate Has a Better Yield (Yield >50%) of Microbiological Organisms Than Sputum Culture (Ann Am Thorac Soc, 2016) [MEDLINE]

Recommendations (American Thoracic Society and Infectious Diseases Society of America 2007 Consensus Guidelines on the Management of Community-Acquired Pneumonia in Adults) (Clin Infect Dis, 2007) [MEDLINE]

Recommendations (American Thoracic Society and Infectious Diseases Society of America 2019 Clinical Practice Guidelines for the Diagnosis and Treatment of Adults with Community-Acquired Pneumonia) (Am J Respir Crit Care Med, 2019) [MEDLINE]

  • Indications for Sputum Gram Stain/Culture (Any of the Following)
    • Empiric Treatment for Either Methicillin-Resistant Staphylococcus Aureus (MRSA) or Pseudomonas Aeruginosa (Strong Recommendation, Very Low Quality of Evidence)
    • Prior Infection with Methicillin-Resistant Staphylococcus Aureus (MRSA) or Pseudomonas Aeruginosa (Especially Prior Respiratory Tract Infection) (Conditional Recommendation, Very Low Quality of Evidence)
      • These are the Strongest Risk Factors for Methicillin-Resistant Staphylococcus Aureus (MRSA) or Pseudomonas Aeruginosa Community-Acquired Pneumonia
    • Prior Hospitalization or Receipt of Parenteral Antibiotics within the Last 90 Days (Conditional Recommendation, Very Low Quality of Evidence)
      • These Factors Increase the Risk of Methicillin-Resistant Staphylococcus Aureus (MRSA) or Pseudomonas Aeruginosa Community-Acquired Pneumonia
    • Severe Community-Acquired Pneumonia (Especially if the Patient is Intubated), as Defined by the Following (Strong Recommendation, Very Low Quality of Evidence)
      • General Comments
        • Validated Definition of Severe Community-Acquired Pneumonia Includes Either 1 Major Criterion or ≥3 Minor Criteria
      • Major Criteria
        • Respiratory Failure Requiring Invasive Mechanical Ventilation
        • Septic Shock Requiring Vasopressors
      • Minor Criteria
        • Altered Mental Status
        • Hypotension Requiring Aggressive Intravenous Fluid Resuscitation
        • Hypothermia (Core Temperature <36°C)
        • Leukopenia (WBC <4000 Cells/mm3)
        • Multilobar Infiltrates
        • pO2/FiO2 Ratio ≤250
        • Tachypnea (Respiratory Rate ≥30 Breaths/min)
        • Thrombocytopenia (Platelets <100k Cells/mm3)
        • Uremia (BUN ≥20 mg/dL)

Nasal Methicillin-Resistant Staphylococcus Aureus (MRSA) Testing (see Nasal Methicillin-Resistant Staphylococcus Aureus Testing)

Clinical Efficacy

  • Meta-Analysis of Methicillin-Resistant Staphylococcus Aureus (MRSA) Nasal Screening to Rule Out MRSA Pneumonia (Clin Infect Dis, 2018) [MEDLINE]: n = 1,563 (22 studies)
    • For All MRSA Pneumonia Types
      • Pooled Sensitivity of MRSA Nare Testing for All MRSA Pneumonia Types: 70.9%
      • Pooled Specificity of MRSA Nare Testing for All MRSA Pneumonia Types: 90.3%
      • With a 10% Prevalence of Potential MRSA Pneumonia, the Calculated Positive Predictive Value was 44.8% and the Negative Predictive Value was 96.5%
    • For Community-Acquired Pneumonia (CAP) and Healthcare-Associated MRSA Pneumonia (HCAP)
      • Pooled Sensitivity of MRSA Nare Testing for All MRSA Pneumonia Types: 85%
      • Pooled Specificity of MRSA Nare Testing for All MRSA Pneumonia Types: 92.1%
      • With a 10% Prevalence of Potential MRSA Pneumonia, the Calculated Positive Predictive Value was 56.8% and the Negative Predictive Value was 98.1%
    • For Ventilator-Associated MRSA Pneumonia
      • Pooled Sensitivity of MRSA Nare Testing for All MRSA Pneumonia Types: 40.3%
      • Pooled Specificity of MRSA Nare Testing for All MRSA Pneumonia Types: 93.7%
      • With a 10% Prevalence of Potential MRSA Pneumonia, the Calculated Positive Predictive Value was 35.7% and the Negative Predictive Value was 94.8%
  • Data Supporting the Negative Predictive Value of Rapid Methicillin-Resistant Staphylococcus Aureus (MRSA) Testing are Robust (American Thoracic Society and Infectious Diseases Society of America 2019 Clinical Practice Guidelines for the Diagnosis and Treatment of Adults with Community-Acquired Pneumonia) (Am J Respir Crit Care Med, 2019) [MEDLINE]
    • Treatment for Methicillin-Resistant Staphylococcus Aureus (MRSA) Pneumonia Can Generally Be Withheld When the Nasal Methicillin-Resistant Staphylococcus Aureus (MRSA) Swab is Negative, Especially in Non-Severe Community-Acquired Pneumonia
    • However, the Positive Predictive Value of Methicillin-Resistant Staphylococcus Aureus (MRSA) Culture is Not as High
      • Therefore, When the Nasal Methicillin-Resistant Staphylococcus Aureus (MRSA) Swab is Positive, Coverage for Methicillin-Resistant Staphylococcus Aureus (MRSA) Pneumonia Should Generally Be Initiated (In the Specific Clinical Situations Noted Below), But Blood/Sputum Cultures Should Be Obtained and Therapy Deescalated if Cultures are Negative

Urinary Histoplasma Antigen (see Urinary Histoplasma Antigen)

  • May Be Indicated in Select Cases

Legionella Testing

Techniques

  • Urinary Legionella Antigen (see Urinary Legionella Antigen)
    • Urinary Legionella Antigen Remains Positive for Days After the Start of Antibiotic Treatment
  • Endotracheal Aspirate/Bronchoalveolar Lavage (BAL) Legionella Culture on Selective Media
  • Legionella Direct Fluorescent Antigen (DFA) (see Legionella Direct Fluorescent Antigen)
  • Legionella Polymerase Chain Reaction (PCR) Test

Clinical Efficacy

  • xxx

Recommendations (American Thoracic Society and Infectious Diseases Society of America 2007 Consensus Guidelines on the Management of Community-Acquired Pneumonia in Adults) (Clin Infect Dis, 2007) [MEDLINE]

  • Indications for Urinary Legionella Antigen Testing
    • Active Alcohol Abuse (see Ethanol)
    • Failure of Outpatient Antibiotic Therapy
    • Intensive Care Unit (ICU) Admission
    • Pleural Effusion (see Pleural Effusion-General)
    • Recent Travel within the Past 2 wks

Recommendations (American Thoracic Society and Infectious Diseases Society of America 2019 Clinical Practice Guidelines for the Diagnosis and Treatment of Adults with Community-Acquired Pneumonia) (Am J Respir Crit Care Med, 2019) [MEDLINE]

  • Routine Urine Legionella Antigen Testing is Not Recommended in Adults with Community-Acquired Pneumonia (Conditional Recommendation, Low Quality of Evidence)
  • Urine Legionella Antigen Testing is Recommended in Adults with Community-Acquired Pneumonia with Either of the Following
    • Presence of Either Epidemiologic Risk Factors for Legionella (Conditional Recommendation, Low Quality of Evidence
      • Association with Legionella Outbreak
      • Recent Travel
    • Severe Community-Acquired Pneumonia (Especially if the Patient is Intubated), as Defined by the Following (Conditional Recommendation, Low Quality of Evidence
      • General Comments
        • Validated Definition of Severe Community-Acquired Pneumonia Includes Either 1 Major Criterion or ≥3 Minor Criteria
      • Major Criteria
        • Respiratory Failure Requiring Invasive Mechanical Ventilation
        • Septic Shock Requiring Vasopressors
      • Minor Criteria
        • Altered Mental Status
        • Hypotension Requiring Aggressive Intravenous Fluid Resuscitation
        • Hypothermia (Core Temperature <36°C)
        • Leukopenia (WBC <4000 Cells/mm3)
        • Multilobar Infiltrates
        • pO2/FiO2 Ratio ≤250
        • Tachypnea (Respiratory Rate ≥30 Breaths/min)
        • Thrombocytopenia (Platelets <100k Cells/mm3)
        • Uremia (BUN ≥20 mg/dL)
  • In Adults with Severe Community-Acquired Pneumonia, Legionella Testing Should Consist of Both of the Following (Conditional Recommendation, Low Quality of Evidence)
    • Urinary Legionella Antigen Test (see Urinary Legionella Antigen)
    • Lower Respiratory Tract Specimen with Legionella Culture on Selective Media or Legionella Polymerase Chain Reaction (PCR) Test

Urinary Pneumococcal Antigen (see Urinary Pneumococcal Antigen)

Technique

  • Urinary Pneumococcal Antigen Remains Positive for Days After the Start of Antibiotic Treatment

Recommendations (American Thoracic Society and Infectious Diseases Society of America 2007 Consensus Guidelines on the Management of Community-Acquired Pneumonia in Adults) (Clin Infect Dis, 2007) [MEDLINE]

Recommendations (American Thoracic Society and Infectious Diseases Society of America 2019 Clinical Practice Guidelines for the Diagnosis and Treatment of Adults with Community-Acquired Pneumonia) (Am J Respir Crit Care Med, 2019) [MEDLINE]

  • Routine Urine Pneumococcal Antigen Testing is Not Recommended in Adults with Community-Acquired Pneumonia (Conditional Recommendation, Low Quality of Evidence)
  • Urine Pneumococcal Antigen Testing is Recommended in Adults with Severe Community-Acquired Pneumonia, as Defined by the Following (Conditional Recommendation, Low Quality of Evidence)
    • General Comments
      • Validated Definition of Severe Community-Acquired Pneumonia Includes Either 1 Major Criterion or ≥3 Minor Criteria
    • Major Criteria
      • Respiratory Failure Requiring Invasive Mechanical Ventilation
      • Septic Shock Requiring Vasopressors
    • Minor Criteria
      • Altered Mental Status
      • Hypotension Requiring Aggressive Intravenous Fluid Resuscitation
      • Hypothermia (Core Temperature <36°C)
      • Leukopenia (WBC <4000 Cells/mm3)
      • Multilobar Infiltrates
      • pO2/FiO2 Ratio ≤250
      • Tachypnea (Respiratory Rate ≥30 Breaths/min)
      • Thrombocytopenia (Platelets <100k Cells/mm3)
      • Uremia (BUN ≥20 mg/dL)

Nasal Influenza Testing (see Influenza Virus)

Background

  • Study Examining the Use of Influenza Testing in US Hospitals from 2010-2015 (Chest, 2022) [MEDLINE]: n = 166,268 patients with community-acquired pneumonia (data from 179 Hospitals in the Premier Database)
    • Only 35.6% of the Community-Acquired Pneumonia Patients were Tested for Influenza
      • Interestingly, the Rates of Influenza Testing were Low Even During Influenza Season
    • Influenza-Positive Patients Received Antiviral Agents More Often and Antibacterial Agents Less Often and for Shorter Courses than Influenza-Negative Patients (5.3 vs 6.4 Days; P < 0.001)
    • Influenza-Positive Patients Receiving Oseltamivir on Hospital Day 1 (n = 2,585) Had a Lower 14-Day In-Hospital Mortality Rate (Adjusted Odds Ratio 0.75; 95% CI: 0.59-0.96), Lower Costs (Adjusted Ratio of Means 0.88; 95% CI: 0.81-0.95), and Shorter Length of Stay (Adjusted Ratio of Means 0.88; 95% CI: 0.84-0.93) vs Patients Receiving Oseltamivir Later or Not at All (n = 1,742)

Recommendations (American Thoracic Society and Infectious Diseases Society of America 2019 Clinical Practice Guidelines for the Diagnosis and Treatment of Adults with Community-Acquired Pneumonia) (Am J Respir Crit Care Med, 2019) [MEDLINE]

  • In the Setting of Community-Acquired Pneumonia, When Influenza Viruses are Circulating in the Community, Testing for Influenza with a Rapid Influenza Molecular Assay (i.e. Influenza Nucleic Acid Amplification Test) is Recommended Over a Rapid Influenza Diagnostic Test (i.e. Antigen Test) (Strong Recommendation, Moderate Quality of Evidence
    • The Benefits of Antiviral Therapy Support Testing of Patients During Periods of High Influenza Activity
    • During Periods of Low Influenza Activity in the Community, Testing Can Be Considered, But May Not Be Routinely Performed

Recommendations for Diagnostic Testing for Influenza (Clinical Practice Guidelines by the Infectious Diseases Society of America: 2018 Update on Diagnosis, Treatment, Chemoprophylaxis, and Institutional Outbreak Management of Seasonal Influenza) (Clin Infect Dis, 2019) [MEDLINE]

Which Patients Should Be Tested for Influenza
  • Outpatients (including the Emergency Department)
    • During Influenza Activity (Defined as the Circulation of Seasonal Influenza A/B Viruses in the Local Community)
      • Clinicians Should Test for Influenza in High-Risk Patients, Including Immunocompromised Patients Who Present with Influenza-Like Illness, Pneumonia, or Nonspecific Respiratory Illness (i.e. Cough without Fever) if the Testing Result Will Influence Clinical Management (A–III)
      • Clinicians Should Test for Influenza in Patients Who Present with Acute Onset of Respiratory Symptoms with/without Fever, and Either Exacerbation of Chronic Medical Conditions (Asthma, Chronic Obstructive Pulmonary Disease, Heart Failure) or Known Complications of Influenza (Pneumonia) if the Testing Result Will Influence Clinical Management (A-III)
      • Clinicians Can Consider Influenza Testing for Patients Not at High Risk for Influenza Complications Who Present with Influenza-Like Illness, Pneumonia, or Nonspecific Respiratory Illness (i.e. Cough without Fever) and Who are Likely to Be Discharged Home if the Results Might Influence Antiviral Treatment Decisions or Reduce the Use of Unnecessary Antibiotics, Further Diagnostic Testing, and Time in the Emergency Department, or if the Results Might Influence Antiviral Treatment or Chemoprophylaxis Decisions for High-Risk Household Contacts (C-III)
    • During Low Influenza Activity without Any Link to an Influenza Outbreak
      • Clinicians Can Consider Influenza Testing in Patients with Acute Onset of Respiratory Symptoms with/without Fever (Especially for Immunocompromised and High-Risk Patients) (B-III)
  • Inpatients
    • During Influenza Activity (Defined as the Circulation of Seasonal Influenza A/B Viruses in the Local Community)
      • Clinicians Should Test for Influenza on Admission in All Patients Requiring Hospitalization with Acute Respiratory illness (Including Pneumonia) with/without Fever (A-II)
      • Clinicians Should Test for Influenza on Admission in All Patients with Acute Worsening of Chronic Cardiopulmonary Disease (Asthma, Chronic Obstructive Pulmonary Disease, Coronary Artery Disease, or Heart Failure), as Influenza Can Be Associated with Exacerbation of Underlying Conditions (A-III)
      • Clinicians Should Test for Influenza on Admission in All Patients Who are Immunocompromised or at High Risk of Complications and Present with Acute Onset of Respiratory Symptoms with/without Fever, as the Manifestations of Influenza in Such Patients are Frequently Less Characteristic than in Immunocompetent Individuals (A-III)
      • Clinicians Should Test for Influenza in All Patients Who, While Hospitalized, Develop Acute Onset of Respiratory Symptoms, with/without Fever, or Respiratory Distress, without a Clear Alternative Diagnosis (A-III)
    • During Low Influenza Activity without Any Link to an Influenza Outbreak
      • Clinicians Should Test for Influenza on Admission in All Patients Requiring Hospitalization with Acute Respiratory Illness, with/without Fever, Who Have an Epidemiological Link to a Patient Diagnosed with Influenza, an Influenza Outbreak or Outbreak of Acute Febrile Respiratory Illness of Uncertain Etiology, or Who Recently Traveled from an Area with Known Influenza Activity (A-II)
      • Clinicians Can Consider Testing for Influenza in Patients with Acute, Febrile Respiratory Tract illness, Especially Children and Adults Who are Immunocompromised or at High Risk of Influenza Complications, or if the Results Might Influence Antiviral Treatment or Chemoprophylaxis Decisions for High-Risk Household Contacts (B-III)

Nucleic Acid Testing for Respiratory Pathogens

General Comments

  • Note that in Rhinovirus Infection, Asymptomatic Viral Shedding is Common, Making Multiplex Testing of Unclear Utility (Since No Specific Therapy is Available, Regardless)
    • Positive Rhinovirus PCR Has Been Reported in 6% of Asymptomatic Adults and 35% of Asymptomatic Children at Any Given Point in Time (mSphere, 2018) [MEDLINE] (Pediatrics, 2014) [MEDLINE] (J Infect Dis, 2018) [MEDLINE]

Diagnostic Testing for Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) (see Severe Acute Respiratory Syndrome Coronavirus-2)

  • In Any Patient Presenting with an Acute Respiratory Illness, an Oropharyngeal Swab with Reverse-Transcriptase Polymerase Chain Reaction (RT-PCR) Testing for SARS-CoV-2 is Required for the Purpose of Infection Control

Clinical Efficacy

  • In Patients Hospitalized with Community-Acquired Pneumoniaa, >95% of Patients Received Antibiotics Regardless of Whether They were Found to Be Respiratory Virus Panel Negative or Positive (Am J Infect Control, 2017) [MEDLINE]

BioFire Panel (Biomérieux)

Rapid Microbiologic Diagnostic Platforms (RMDP) (see xxxx)

  • LightCycler SeptiFast Test (Roche)
  • Peptide Nucleic Acid Fluorescence in Situ Hybridization (PNA-FISH) (AdvanDx)
  • Matrix-Assisted Laser Desorption-Ionization Time-of-Flight (MALDI-TOF) Mass Spectrometry (MS) (VITEK MS; bioMérieux)
  • Polymerase Chain Reaction (PCR) Combined with Electrospray Ionization Mass Spectrometry (PCR/ESI-MS) (Abbott Ibis Biosciences)
  • DNA-Based Microarray Platforms
    • Prove-it Sepsis Assay (Mobidiag)
    • Verigene Gram-Positive Blood Culture Assay (Nanosphere)
  • ID/AST System (Accelerate Diagnostics)
    • Automated Microscopy System, Currently in Development

Recommendations (American Thoracic Society Clinical Practice Guideline for Nucleic Acid-based Testing for Noninfluenza Viral Pathogens in Adults with Suspected Community-Acquired Pneumonia) (Am J Respir Crit Care Med, 2021) [MEDLINE]

  • In Outpatients with Suspected Community-Acquired Pneumonia, Routine Nucleic Acid–Based Testing of Respiratory Samples for Viral Pathogens Other than Influenza (and Presumably SARS-CoV-2) is Not Recommended (Conditional Recommendation, Very Low Quality Evidence)
  • In Inpatients with Suspected Community-Acquired Pneumonia, Nucleic Acid–Based Testing of Respiratory Samples for Viral Pathogens Other than Influenza (and Presumably SARS-CoV-2) is Recommended Only in the Following Groups (Conditional Recommendation, Very Low Quality Evidence)
    • Patients with Severe Community-Acquired Pneumonia, as Defined by the Following
      • General Comments
        • Validated Definition of Severe Community-Acquired Pneumonia Includes Either 1 Major Criterion or ≥3 Minor Criteria
      • Major Criteria
        • Respiratory Failure Requiring Invasive Mechanical Ventilation
        • Septic Shock Requiring Vasopressors
      • Minor Criteria
        • Altered Mental Status
        • Hypotension Requiring Aggressive Intravenous Fluid Resuscitation
        • Hypothermia (Core Temperature <36°C)
        • Leukopenia (WBC <4000 Cells/mm3)
        • Multilobar Infiltrates
        • pO2/FiO2 Ratio ≤250
        • Tachypnea (Respiratory Rate ≥30 Breaths/min)
        • Thrombocytopenia (Platelets <100k Cells/mm3)
        • Uremia (BUN ≥20 mg/dL)
    • Immunocompromised State, as Defined by Any of the Following
      • Active Cancer Therapy
      • Advanced Human Immunodeficiency Virus (HIV) Disease (see Human Immunodeficiency Virus)
      • Chronic Use of Immunosuppressive Medications (Including Systemic Corticosteroids)
      • History of Solid-Organ/Blood Component Transplant
      • Neutropenia (see Neutropenia)

Bronchoscopy (see Bronchoscopy)

Procedures

  • Bronchoalveolar Lavage (BAL)

Recommendations (American Thoracic Society and Infectious Diseases Society of America 2007 Consensus Guidelines on the Management of Community-Acquired Pneumonia in Adults) (Clin Infect Dis, 2007) [MEDLINE]

  • Bronchoscopy May Be Indicated for Patient with Community-Acquired Pneumonia Who is Admitted to the Intensive Care Unit (ICU)

Thoracentesis (see Thoracentesis)


Clinical Classification of Pneumonia (Infectious Diseases Society of America, IDSA/American Thoracic Society, ATS 2016 Clinical Practice Guidelines for the Management of HAP/VAP (Clin Infect Dis, 2016) [MEDLINE]

Pneumonia (see Pneumonia)

  • Definition: lung infiltrate associated with clinical evidence that an infiltrate is of an infectious origin (new onset of fever, purulent sputum, leukocytosis, and decline in oxygenation)

Community-Acquired Pneumonia (CAP)

  • Definition
    • Pneumonia Which Occurs Either as Outpatient or Within 48 hrs of Hospital Admission
  • Criteria for Severe Community-Acquired Pneumonia (Infectious Diseases Society of America, IDSA/American Thoracic Society, ATS 2007 Consensus Guidelines for the Management of CAP) (Clin Infect Dis, 2007) [MEDLINE]
    • General Comments
      • Validated Definition of Severe Community-Acquired Pneumonia Includes Either 1 Major Criterion or ≥3 Minor Criteria
    • Major Criteria
      • Respiratory Failure Requiring Invasive Mechanical Ventilation
      • Septic Shock Requiring Vasopressors
    • Minor Criteria
      • Altered Mental Status
      • Hypotension Requiring Aggressive Intravenous Fluid Resuscitation
      • Hypothermia (Core Temperature <36°C)
      • Leukopenia (WBC <4000 Cells/mm3)
      • Multilobar Infiltrates
      • pO2/FiO2 Ratio ≤250
      • Tachypnea (Respiratory Rate ≥30 Breaths/min)
      • Thrombocytopenia (Platelets <100k Cells/mm3)
      • Uremia (BUN ≥20 mg/dL)

Healthcare-Associated Pneumonia (HCAP)

  • Definition
    • Pneumonia Which Occurs in a Patient Who Has One of the Following Risk Factors for Multidrug-Resistant Pathogens
      • Chronic Hemodialysis Within 30 Days
      • Family Member with a Multidrug-Resistant Pathogen
      • Home Intravenous Infusion Therapy (Antibiotics, etc)
      • Home Wound Care
      • Residence in a Long-Term Nursing Home/Extended Care Facility
      • Stay in an Acute Care Hospital for ≥2 Days in the Last 90 Days

Hospital-Acquired Pneumonia (HAP) (see Hospital-Acquired Pneumonia and Ventilator-Associated Pneumonia)

  • Definition
    • Pneumonia Which is Not Incubating at the Time of Hospital Admission and Which Occurs ≥48 hrs After Admission
      • This Definition Importantly Excludes Any Pneumonia Which is Associated with Mechanical Ventilation

Ventilator-Associated Tracheobronchitis

  • Definition
    • Fever (Without Another Recognizable Cause) Associated with New or Increased Sputum Production, Positive Endotracheal Aspirate Culture (>10 to the 6th CFU/mL) Yielding a New Bacteria and No Radiographic Evidence of Pneumonia (Crit Care, 2005) [MEDLINE]

Ventilator-Associated Pneumonia (VAP) (see Hospital-Acquired Pneumonia and Ventilator-Associated Pneumonia)

  • Definition
    • Pneumonia Which Occurs >48 hours After Endotracheal Intubation
  • Clinical Types of Ventilator-Associated Pneumonia
    • Early Onset Ventilator-Associated Pneumonia (Within 5 Days of Intubation): usually results from aspiration
    • Late Onset Ventilator-Associated Pneumonia (After 5 Days of Intubation): usually caused by antibiotic-resistant pathogens and is associated with increased morbidity and mortality


Clinical-Pneumonia Scoring

Clinical Pneumonia Scoring Systems

  • Pneumonia Severity Index (PSI)
  • CURB-65
  • SOFA

Clinical Data

  • Spanish Cohort Study Comparing Community-Acquired Pneumonia (CAP) Severity Indices in Predicting the In-Hospital Mortality Rate (Am J Respir Crit Care Med, 2017) [MEDLINE]: n = 6874
    • Overall 6.4% of Patients Died in the Hospital
    • Most Accurate Predictors: PSI > CURB-65 > mSOFA> CRB > qSOFA > SIRS
    • qSOFA and CRB (Confusion, Respiratory Rate and Blood Pressure) Criteria Outperformed SIRS and Had Better Clinical Usefulness as Prompt Tools for CAP patients in the Emergency Department
    • PSI (Pneumonia Severity Index) was More Accurate at Predicting In-Hospital Mortality than mSOFA and CURB-65


Clinical Manifestations

Pulmonary Manifestations

Clinical Efficacy of Symptoms and Signs in the Diagnosis of Community-Acquired Pneumonia (CAP)

  • Army Medical Center Emergency Department Study of the Diehr Rule for the Prediction of Pneumonia in Patients Presenting with Acute Cough (J Chronic Dis, 1984) [MEDLINE]: n = 1,819
    • Pneumonia was Radiographically Diagnosed in 2.6% of the Patients
    • Clinical Decision Rule (Developed in 1,00 of Patients, Validated in 483 Patients)
      • Rhinorrhea: -2 point
      • Sore Throat: -1 point
      • Night Sweats/Myalgias/All-Day Sputum Production: 1 point
      • Respiratory Rate >25 breaths/min: 2 points
      • T >100 °F (37.8 °C)
    • Interpretation of Score
      • Score of -2 to -3 Points: likelihood of pneumonia was<1%
      • Score of 3-6 Points: likelihood of pneumonia was 27%
  • Emergency Department Study of Gennis Rule for the Diagnosis of Pneumonia (J Emerg Med, 1989) [MEDLINE]: n= 308
    • 38% of the Patients Had Radiographic Pneumonia
    • Symptoms
      • No Single Symptom or Sign was Reliably Predictive of Pneumonia
      • Cough was the Most Common Symptom (Present in 86% of Cases, But was Equally Common in Patients without Pneumonia)
      • Fever was Absent in 31% of Patients with Pneumonia
      • Abnormal Lung Exam (Rales, Rhonchi, Decreased Breath Sounds, Wheezes, Altered Fremitus, Egophony, Dullness to Percussion) were Found in <50% of the Patients with Pneumonia and 22% of Patients with a Completely Normal Lung Exam Had Pneumonia
    • Rule Criteria for Obtaining a Chest X-Ray, Based on Presence of At Least One of the Following (97% Sensitivity)
      • Temperature >100 °F (37.8 °C)
      • Heart Rate >100 beats/min
      • Respiratory Rate >20 breaths/min
  • Emergency Department Prospective Observational Study of Singal Rule for the Diagnosis of Pneumonia (Ann Emerg Med, 1989) [MEDLINE]: n = 255 adults
    • 15.6% of Adult Patients Had Radiographic Pneumonia
    • Univariate Predictors of Pneumonia were Fever, Cough, Crackles
      • In Absence of Fever, Cough, and Crackles, Incidence of Pneumonia was Only 4.3%
  • Emergency Department Study of the Heckerling Rule for the Diagnosis of Pneumonia (Ann Intern Med, 1990) [MEDLINE]: n= 1,436 (3 different emergency departments)
    • Rule was Developed in 1,134 Patients and Validated in 302 Patients
    • Rule Criteria for Obtaining a Chest X-Ray (from Stepwise Logistic Regression Model; p <0.001)
      • Temperature >100 °F (37.8 °C): 1 point
      • Heart Rate >100 beats/min: 1 point
      • Crackles: 1 point
      • Decreased Breath Sounds (Locally): 1 point
      • Absence of Asthma: 1 point
    • Interpretation of Score (Pre-Test Probability was 5% in Primary Care and 15% in Emergency Department)
      • Score 0
        • Post-Test Probability of Pneumonia (Primary Care): 1%
        • Post-Test Probability of Pneumonia (Emergency Department): 2%
        • Likelihood Ratio: 0.12
      • Score 1
        • Post-Test Probability of Pneumonia (Primary Care): 1%
        • Post-Test Probability of Pneumonia (Emergency Department): 3%
        • Likelihood Ratio: 0.2
      • Score 2
        • Post-Test Probability of Pneumonia (Primary Care): 4%
        • Post-Test Probability of Pneumonia (Emergency Department): 11%
        • Likelihood Ratio: 0.7
      • Score 3
        • Post-Test Probability of Pneumonia (Primary Care): 8%
        • Post-Test Probability of Pneumonia (Emergency Department): 22%
        • Likelihood Ratio: 1.6
      • Score 4
        • Post-Test Probability of Pneumonia (Primary Care): 27%
        • Post-Test Probability of Pneumonia (Emergency Department): 56%
        • Likelihood Ratio: 7.2
      • Score 5
        • Post-Test Probability of Pneumonia (Primary Care): 47%
        • Post-Test Probability of Pneumonia (Emergency Department): 75%
        • Likelihood Ratio: 17
    • Rule Had a Receiver Operating Characteristic (ROC) Area 0.82
      • In the Validation Sets, the Rule Discriminated Pneumonia and Non-Pneumonia with ROC Areas of 0.82 and 0.76 (After Adjusting for Differences in Disease Prevalence)
  • Comparative Prospective Study of Diehr/Gennis/Heckerling/Singal Rules with Physician Judgement for the Diagnosis of Pneumonia in Emergency Department and Outpatient Settings (Ann Emerg Med, 1991) [MEDLINE]: n = 290
    • All Patients Had an Acute Cough and Fever, Hemoptysis, or Sputum Production

Abnormal Pulmonary Exam Findings

  • Findings Consistent with Consolidation (Alveolar Filling Process)
    • Bronchial Breath Sounds [LINK]
      • Due to Improved Transmission of Bronchial Breath Sounds Through the Consolidated Lung (Which Has Higher Density)
    • Crackles [LINK]
    • Dulness to Percussion [LINK]
      • Due to Increased Density of Consolidated Lung (Which Has Higher Density)
    • Increased Tactile Fremitus [LINK]
      • Due to Sound Traveling 4x Faster Through Water (Higher Density) than Through Air (Lower Density)
    • Increased Whispered Pectoriloquy [LINK]
      • Due to Sound Traveling 4x Faster Through Water (Higher Density) than Through Air (Lower Density)
    • Egophony (E -> A Changes) [LINK]
      • Due to Low-Pass Frequency Filter Effect (Stiff Barrier Attenuates High Frequencies and Allows Low Frequencies to Pass Through)
  • XXXX

Cough with Sputum Production (see Cough)

  • XXXX

Dyspnea (see Dyspnea)

  • XXXX

Hypoxemia (see Hypoxemia)

  • XXXX

Parapneumonic Effusion (see Pleural Effusion-Parapneumonic)

  • Presence of Pleural Effusion at Emergency Department Presentation with Pneumonia Predicts an Increasing Likelihood of Being Admitted, Longer Hospital Stay, and Increased 30-Day Mortality Rate (Chest, 2016) [MEDLINE]

Pleuritic Chest Pain (see Chest Pain)

  • XXXX

Other Manifestations


References

General

Epidemiology

Microbiology

Diagnosis

General

Chest X-Ray (see Chest X-Ray)

Serum Procalcitonin (see Serum Procalcitonin)

Nasal Influenza Testing (see Influenza Virus)

Clinical

General

Clinical-Pneumonia Scoring

Prevention