Athina Avlamis

Moxifloxacin resistance is prevalent among Bacteroides and Prevotella species in Greece

OBJECTIVES Moxifloxacin is recommended in the empirical treatment of infections involving Gram-negative anaerobes. However, current European data regarding its activity against anaerobic pathogens are limited. In order to evaluate its potency, we comparatively studied the activity of moxifloxacin against recently isolated Gram-negative anaerobes. METHODS Four hundred and ninety-five Gram-negative anaerobic clinical isolates (296 Bacteroides fragilis group, 58 non-fragilis Bacteroides spp. and 141 Prevotella spp.) were prospectively recovered in six Greek hospitals. Moxifloxacin MICs were determined in comparison with those of penicillin, piperacillin/tazobactam, cefoxitin, imipenem, metronidazole and clindamycin. RESULTS Overall moxifloxacin MIC(50) and MIC(90) were 2 and 32 mg/L, respectively. Based on the current CLSI breakpoints (susceptible, < or =2 mg/L; resistant, > or =8 mg/L), almost half of the total isolates (49%) were non-susceptible to moxifloxacin (32% resistant; 17% intermediate). This was more evident among the non-fragilis Bacteroides species, where 47% of the isolates were resistant and 14% intermediate to moxifloxacin. Species variation was noticed, with the highest non-susceptible rates detected among Prevotella oralis (90%), Prevotella bivia (80%), Bacteroides thetaiotaomicron (75%), Bacteroides uniformis (70%) and Bacteroides capillosus (67%) species. Among the 19 (4%) isolates that were metronidazole non-susceptible (MIC > or = 16 mg/L), only 4 (21%) were additionally non-susceptible to moxifloxacin. CONCLUSIONS High resistance rates to moxifloxacin among Bacteroides and Prevotella spp. were recorded, exceeding those previously reported in Europe and contraindicating its use as monotherapy for infections involving Gram-negative anaerobes without prior microbiological confirmation. For empirical usage, moxifloxacin should be combined with metronidazole in order to cover for these pathogens.

Two Cases of Infections Due to Multidrug-Resistant Bacteroides fragilis Group Strains

ABSTRACT Bacteroides fragilis group strains are still considered susceptible to most antimicrobial agents used for the treatment of infections caused by anaerobic organisms. We describe two cases of infections due to isolates simultaneously resistant to clindamycin, tetracycline, cefoxitin, piperacillin-tazobactam, and imipenem and, in one of the two cases, to metronidazole. Such infections, although still rare, do exist and tend to complicate treatment.

Changes in the epidemiology of methicillin-resistant Staphylococcus aureus in a Greek tertiary care hospital, over an 8-year-period

A total of 1019 non-replicate, consecutively isolated methicillin-resistant Staphylococcus aureus (MRSA) strains were collected from in-patients of a tertiary care general hospital in Athens, Greece, during the period 1994-2001. The susceptibility, resistance phenotypes and the dissemination of these isolates among hospital wards were studied. Total MRSA and gentamicin-resistant MRSA, as a proportion of the S. aureus isolates, increased from 33 and 9% in 1994 to 50.1 and 33.3% in 2001, respectively. Three main multi-resistant phenotypes predominated, representing 50.9% of the total MRSA isolates in 2001. MRSA strains susceptible to all antibiotics tested decreased to 1.9% in 1997 and again increased to 13.5% in 2001. A gradual decrease in the susceptibility of vancomycin during the 8-year-period was detected, but no vancomycin resistant S. aureus strains were isolated.

Risk Factors for Coexistence of Fluoroquinolone Resistance and ESBL Production among Enterobacteriaceae in a Greek University Hospital

Abstract The purpose of this study was to identify risk factors for fluoroquinolone resist-ance (QR) among ESBL-producing Enterobacteriaceae causing nosocomial infections. The study was conducted in Laikon General Hospital in Athens, Greece, during the period January 2004 - January 2005. Epidemiological and clinical data were collected from the medical charts of the patients diagnosed with nosocomial infections due to an ESBL-producing Enterobacteriaceae. QR was 60% among the 84 ESBL-producing Enterobacteriaceae isolates. Infection from QR-ESBL bacteria was associated with increased hospital stay (p=0.028); QR-ESBL bacteria were isolated later during hospitalization than fluoroquinolone suscep-tible (QS)-ESBL (p=0.089); factors associated with QR were immune-deficiency (p=0.047), previous use of carbapenems (p=0.08) and fluoroquinolones (p=0.067), and admission to the Transplantation Unit (p=0.047). In addition, QR-ESBL bacteria were more likely to be resistant to co-trimoxazole (p<0.001), gentamicin (p=0.054) and tobramycin (p=0.004). Logistic regression analysis indicated that admission to the transplantation unit was an independent risk factor for infection due to a QR-ESBL isolate. Results of this study question ciprofloxacins usefulness as a valid alternative to carbapenems in our hospital for the treatment of infections due to ESBL-producing bacteria. In addition strategies for addressing the QR-ESBL situation should focus on limiting fluoroquinolone and carbapenem consumption and emphasize on barrier precautions in patients with longer hospitalization, immunosuppression, or admission to the transplantation unit.