Rhodococcus Equi
Epidemiology
- Predisposing Factors:
- Impaired Cell-Mediated Immunity:
- Steroids
- HIV
- Solid Organ Transplantation
- Animal Exposure: reported in most, but not all, patients
Etiology
- Rhodococcus equi infection
- Gram-Positive Coccus or Rod: may stain weakly acid-fast (due to mycolic acid in cell wall), but is much smaller than AFB
- Varies in shape from cocci to curved club shape (frequently misinterpreted as a diphtheroid or bacillus)
Physiology
Diagnosis
- Sputum GS/Cult+Sens:
- Gram-Positive Coccus or Rod: may stain weakly acid-fast (due to mycolic acid in cell wall), but is much smaller than AFB
- Varies in shape from cocci to curved club shape (frequently misinterpreted as a diphtheroid or bacillus)
- FOB:
- CXR/Chest CT Pattern:
- Nodular Infiltrates: gradually cavitate
- Lung Abscess:
- Empyema: may occur
Clinical
- Subacute Onset of Disease (resembling fungal or mycobacterial disease):
Treatment
- Vanco or Erythromycin: agents of choice (as Rhodococcus is intracellular and these agents get into cells readily)
- Addition of Rifampin: may be synergistic
- Prolonged therapy is necessary to prevent relapse
- Alternatives: resistance has been reported to occur while receiving ß-lactams
- Rifampin:
- Chloramphenicol:
References