Antimicrobial resistance in clinical isolates of Streptococcus pneumoniae in a tertiary hospital in Kuwait, 1997-2007: implications for empiric therapy.

OBJECTIVE: This study evaluated antibiotic resistance trends in Streptococcus pneumoniae isolated in a tertiary hospital in Kuwait and its implications for empiric therapy. MATERIALS AND METHODS: Antimicrobial susceptibility of 1353 strains of S. pneumoniae isolated from clinical specimens during 1997-2007 was performed by disc diffusion method. MIC was determined by E test. The results were compared for 1997-2001, 2002-2005 and 2006-2007. RESULTS: The prevalence of resistance for the respective periods were as follows: penicillin, 51.3%, 61.3% and 54.5%; erythromycin, 31.2%, 36.7% and 37.7%; tetracycline, 30.8%, 45.3% and 41.3%; co-trimoxazole, 49.5%, 58.5% and 62.8%; clindamycin, 20.4%, 20.6% and 24.5% and chloramphenicol, 8.1%, 8.9% and 3.7%. All were susceptible to vancomycin and rifampicin. For oxacillin-resistant isolates, penicillin resistance was rare (0.8%) with the new non-meningeal breakpoint. However, using the meningeal breakpoints, resistance increased for penicillin from 0.6%, to 28.7%, for cefotaxime from none to 16.5%, and for ceftriaxone from none to 7%. Intermediate resistance to meropenem increased from 1.7% to 22.4%. Multiple drug resistance increased from 22.4% to 37.8%. CONCLUSION: The study demonstrated that antimicrobial resistance of S. pneumoniae is increasing in Kuwait. However, the results of MIC determinations indicated that penicillin can still be used for therapy of non-meningeal infections. High prevalence of erythromycin resistance suggests that therapy of pneumonia with a macrolide alone may result in failure and should be based on results of susceptibility testing.

Ciprofloxacin treatment failure in a case of typhoid fever caused by Salmonella enterica serotype Paratyphi A with reduced susceptibility to ciprofloxacin.

This report describes a case of ciprofloxacin treatment failure in a patient with enteric fever caused by Salmonella enterica serotype Paratyphi A. The organism was isolated from a blood culture from a patient who was treated with oral ciprofloxacin (500 mg every 12 h) for 13 days. The organism showed reduced susceptibility to ciprofloxacin (MIC 0.75 microg ml-1) and was resistant to nalidixic acid. The patient was then placed on intravenous ceftriaxone (1 g every 12 h) and responded within 3 days. The patient was discharged after 9 days on ceftriaxone with no relapse on follow-up. This case adds to the increasing incidence of treatment failures with ciprofloxacin in typhoid fever caused by typhoid salmonellae with reduced susceptibility to ciprofloxacin. It also highlights the inadequacy of current laboratory methods for fluoroquinolone susceptibility testing in adequately predicting in vivo activity of ciprofloxacin against typhoid salmonellae and supports calls for new guidelines for fluoroquinolone susceptibility testing of these organisms.