Levofloxacin failure in a patient with pneumococcal pneumonia

OBJECTIVE: To report a case of levofloxacin failure in a patient with a penicillin-sensitive Streptococcus pneumoniae pneumonia. CASE SUMMARY: A previously healthy, immunocompetent, 53-year-old white man presented with penicillin-sensitive S. pneumoniae pneumonia. The patient was empirically placed on levofloxacin monotherapy, which was continued due to a local penicillin shortage. When the patient failed to improve, further susceptibility testing was ordered. The organism was found to have a penicillin minimum inhibitory concentration (MIC) of 0.023 μg/mL and a levofloxacin MIC of 6 μg/mL. Effective antimicrobial therapy was delayed, as clinicians did not anticipate fluoroquinolone resistance. DISCUSSION: Newer fluoroquinolones such as levofloxacin have good activity against most S. pneumoniae isolates and are used for the treatment of pneumonia. Although resistance to these agents is rare, it has been reported. Current guidelines from the National Committee for Clinical Laboratory Standards do not recommend initial fluoroquinolone susceptibility testing. CONCLUSIONS: AS fluoroquinolone resistance may not be identified by susceptibility patterns to other antibiotics, early fluoroquinolone susceptibility testing and increased awareness of resistance may aid clinicians in their treatment of pneumococcal disease.