The text below reviews some common bacterial infections and their treatment. The recommendations made here are based on the results of susceptibility studies, clinical trials and the opinions of Medical Letter consultants.

(Vol. 49, p. 66, August 13, 2007) A reader has pointed out that Saccharomyces boulardii is not a separate species, but a strain of Saccharomyces cerevisiae. S. cerevisiae (including S. boulardii) has been reported to cause systemic infection after oral ingestion in both immunocompromised patients and healthy hosts (MJ McCullough et al. J Clin Microbiol 1998; 36:2613).

Probiotics are live, nonpathogenic microorganisms (usually bacteria or yeasts) that have been used for centuries for their potential health benefits. They are currently marketed for prevention and treatment of a variety of disorders, including diarrhea, irritable bowel syndrome and inflammatory bowel disease.

The gram-positive anaerobic bacillus Clostridium difficile is the most common identifiable cause of antibiotic-associated diarrhea. The antibiotics most often implicated have been ampicillin, second and third generation cephalosporins, clindamycin and fluoroquinolones. The emergence in recent years of a new, more toxic epidemic strain (BI/NAP1), possibly related to widespread use of fluoroquinolones, has caused a marked increase in the incidence and severity of C. difficile-associated disease (CDAD).

Methicillin-resistant Staphylococcus aureus (MRSA) infections, which have been a concern for many years, previously occurred primarily in hospitalized patients and those recently treated with antibiotics. In the past few years, there has been an increasing incidence worldwide of community-associated (CA) MRSA infections in patients without recent antibiotic exposure or contact with the healthcare system.