Empiric therapy for cellulitis should cover which organisms?

Empiric therapy for cellulitis should cover which organisms?

• A. Staphylococcus aureus and Streptococcus species
• B. Pseudomonas aeruginosa
• C. Anaerobes only
• D. MRSA only

Answer: (A)

Cellulitis is most often caused by bacteria that live on the skin and in the soft tissues, specifically Staphylococcus aureus and Streptococcus species. Because these two groups account for the vast majority of cases, empiric therapy is aimed at covering both. Pseudomonas aeruginosa is not a typical offender in uncomplicated cellulitis, and anaerobes are not usually the main culprits unless there are special circumstances (like certain bite injuries or very deep infections). MRSA is a real concern in some patients, but treating only MRSA would miss Streptococcus infections that are also common, so the standard initial approach is to cover both Staph aureus and Streptococcus species. If purulent cellulitis or high MRSA risk is present, therapy can be adjusted to include MRSA coverage or later narrowed based on culture results.

Cellulitis is most often caused by bacteria that live on the skin and in the soft tissues, specifically Staphylococcus aureus and Streptococcus species. Because these two groups account for the vast majority of cases, empiric therapy is aimed at covering both. Pseudomonas aeruginosa is not a typical offender in uncomplicated cellulitis, and anaerobes are not usually the main culprits unless there are special circumstances (like certain bite injuries or very deep infections). MRSA is a real concern in some patients, but treating only MRSA would miss Streptococcus infections that are also common, so the standard initial approach is to cover both Staph aureus and Streptococcus species. If purulent cellulitis or high MRSA risk is present, therapy can be adjusted to include MRSA coverage or later narrowed based on culture results.