The Close Relationship between Ciprofloxacin Resistance and Extended-Spectrum beta-Lactamase Production:Analysis of 154 Consecutive Nosocomially-Acquired Klebsiella pneumoniae Bacteremia

ABSTRACT

BACKGROUND: Strains of ciprofloxacin-resistant Klebsiella pneumoniae have emerged worldwide. We investigated the epidemiology of ciprofloxacin resistance and its relationship to ESBL production in nosocomial K. pneumoniae bacteremia. MATERIALS AND METHODS: Using the computerized database of clinical microbiology, we identified all patients whose blood culture had yielded K. pneumoniae between January 2001 and December 2002 at a 2200-bed university-affiliated tertiary-care hospital. During the study period, total of 392 episodes of K. pneumoniae bacteremia were documented of which 163 episodes were acquired nosocomially. 9 cases of recurrent episodes were excluded. RESULTS: The resistance rates to ciprofloxacin was 28.6% (44/154). ESBL-production was significantly more common in ciprofloxacin-resistant isolates than in ciprofloxacin-susceptible isolates (95.9% [42/44] vs. 24.5% [27/110], P<0.001). In univariate analysis, following factors were significantly associated with resistance to ciprofloxacin older age, male sex, ICU admission at the time of bacteremia, prior use of antibiotics within 1 month before bacteremia, solid tumor, hematological malignancy, or biliary disease as underlying disease, and ESBL-production. The prior use of 3rd- generation cephalosprins, metronidazole, fluroquinolone, or carbapenem were also risk factors. Independent risk factors for ciprofloxacin resistance were older age (adjusted odds ratio [AOR]; 1.04, 95% confidence interval [CI]; 1.01-1.06) and ESBL production (AOR; 81.35, 95% CI; 17.76-372.53). CONCLUSION: The close relationship between ciprofloxacin resistance and ESBL production was documented in nosocomial K. pneumoniae bacteremia. Further epidemiological and molecular studies to determine factors and mechanisms involved in the relationship are needed.