Pleural space infections: microbiology and antimicrobial therapy.

Although most recognized pleural space infections are caused by Staphylococcus aureus, Streptococcus pneumoniae, enteric gram-negative bacilli, or anaerobic bacteria, the spectrum of possible pathogens is broad and includes fungi and even protozoa, reflecting the mixed origins of these infections. When pleural space infection is suspected, a diagnostic thoracocentesis is indicated. An immediate gram-stained smear of directly aspirated pleural fluid often can guide the physician's initial treatment. After recovery of the pathogens, optimal antibiotic therapy should be based on standardized susceptibility testing and consensus guidelines. Antibiotic therapy alone may be curative, but adequate drainage must also be achieved in most cases.