Which statement best reflects initial therapy for a Pseudomonas aeruginosa infection?

• A. Ciprofloxacin is never used for Pseudomonas
• B. Vancomycin is first-line therapy
• C. An antipseudomonal beta-lactam such as piperacillin is used
• D. Aminoglycoside alone is sufficient

Answer: (C)

Pseudomonas infections require an antibiotic that has reliable activity against this organism from the start. Pseudomonas has multiple resistance mechanisms, so the initial therapy is a drug with strong anti-pseudomonal beta-lactam activity. Piperacillin, especially when given with a beta-lactamase inhibitor (piperacillin-tazobactam), provides broad and dependable coverage against Pseudomonas and is a common choice for empirical therapy while culture results are pending.

Vancomycin targets gram-positive organisms and does not cover Pseudomonas, so it isn’t appropriate as initial therapy for a suspected pseudomonal infection. Ciprofloxacin can be active against Pseudomonas in some situations, particularly milder cases or step-down therapy, but it isn’t universally appropriate as initial therapy and saying it’s never used isn’t correct. An aminoglycoside alone is not sufficient for initial therapy because mono-therapy may miss other pathogens and carries toxicity risks; it’s usually considered as part of combination therapy rather than as monotherapy.

So, starting with an antipseudomonal beta-lactam like piperacillin (often with beta-lactamase inhibitor) best reflects the correct approach to initial therapy.