Fosfomycin: In vitro efficacy against multidrug-resistant isolates beyond urinary isolates.

OBJECTIVES: Fosfomycin (FOF) is a bactericidal antimicrobial agent active against a range of Gram-negative bacteria, including multidrug-resistant (MDR) and metallo-ß-lactamase (MBL)-producing Enterobacteriaceae. However, data are scarce regarding use of the drug beyond urinary tract infections (UTIs). METHODS: In this study, susceptibility rates to FOF among 290 MDR Enterobacteriaceae isolates were analysed by gradient and disk diffusion tests and the results were compared with agar dilution according to the Clinical and Laboratory Standards Institute (CLSI). Minimum inhibitory concentrations (MICs) of imipenem (IPM) for isolates IPM-resistant/intermediate-susceptible isolates were determined by gradient test. In addition, the gradient test was used to determine MBL production. RESULTS: Of the 290 extended-spectrum ß-lactamase (ESBL)-positive isolates, 60 (20.7%) were resistant to FOF, with rates of 9.5% for Escherichia coli, 28.0% for Enterobacter spp., 35.7% for Klebsiella spp. and 50.0% for Morganella spp. Among the 290 ESBL-positive isolates, 19 (6.6%) were resistant/intermediate-susceptible to IPM. In addition, 72.2% of extensively drug-resistant (XDR) and 61.1% of carbapenem-resistant isolates were resistant to FOF. In vitro FOF activity was higher among blood (86.9%) and genitourinary (91.7%) isolates. FOF showed excellent activity for a wide range of infections; however, further trials are necessary to evaluate its clinical efficacy. CONCLUSIONS: FOF presented good activity even against carbapenem-resistant isolates and may be a treatment alternative for non-UTI isolates, but should be used with caution for infections related to ESBL-producing Klebsiella spp.

Pneumonia due to Enterobacter cancerogenus infection.

Enterobacter cancerogenus (formerly known as CDC Enteric Group 19; synonym with Enterobacter taylorae) has rarely been associated with human infections, and little is known regarding the epidemiology and clinical significance of this organism. We describe a community-acquired pneumonia case in a 44-year-old female due to E. cancerogenus. Identification and antimicrobial susceptibility of the microorganism was performed by the automatized VITEK 2 Compact system (bioMerieux, France). The clinical case suggests that E. cancerogenus is a potentially pathogenic microorganism in determined circumstances; underlying diseases such as bronchial asthma, empiric antibiotic treatment, wounds, diagnostic, or therapeutic instruments.

Evaluation of the in vitro activity of fosfomycin tromethamine against Gram-negative bacterial strains recovered from community- and hospital-acquired urinary tract infections in Turkey.

OBJECTIVES: The aim of this study was to evaluate the in vitro activities of antimicrobial agents including fosfomycin tromethamine against Gram-negative isolates recovered from urine samples. METHODS: A total of 2334 strains (1562 Escherichia coli, 509 Klebsiella spp, 85 Proteus spp, 75 Pseudomonas spp, 45 Enterobacter spp, 37 Acinetobacter baumannii, 8 Citrobacter spp, 7 Morganella morganii, and 6 Serratia spp) were identified by VITEK 2 during the study period, November 2008 to June 2012. Antimicrobial susceptibilities of the strains were also evaluated using the Kirby-Bauer disk diffusion method, in accordance with the Clinical and Laboratory Standards Institute guidelines. RESULTS: Overall, 2160 (92.5%) of the isolates tested were susceptible to fosfomycin tromethamine. Higher resistance rates were observed among inpatients compared to outpatients. Resistance rates by strain were: 2.0% for E. coli, 4.4% for Enterobacter spp, 6.9% for Klebsiella spp, 9.4% for Proteus spp, 48.6% for A. baumannii, 56.0% for Pseudomonas spp, and 100% for Morganella morganii. All Serratia spp and Citrobacter spp strains were susceptible. Extended-spectrum beta-lactamase (ESBL)-producing isolates displayed higher fosfomycin resistance rates than negative strains (19.2% vs. 2.9%). The highest in vitro activity was detected for amikacin, piperacillin-tazobactam, and imipenem for all strains including ESBL-producers. CONCLUSIONS: Regardless of ESBL production, the excellent activity of fosfomycin against E. coli, Enterobacter spp, Serratia spp, and Citrobacter spp, indicates that the drug is a valuable therapeutic option for urinary tract infections, even those with co-trimoxazole- and ciprofloxacin-resistant isolates, but not in ESBL-producing Klebsiella spp, Pseudomonas spp, A. baumannii, and Proteus spp. Further studies should be carried out to determine the in vivo drug activity among Enterobacteriaceae other than E. coli.

Panton-Valentine leucocidin gene carriage among Staphylococcus aureus strains recovered from skin and soft tissue infections in Turkey.

OBJECTIVES: Regardless of methicillin resistance, Panton-Valentine leucocidin (PVL)-positive Staphylococcus aureus isolates are associated with various types of infections and outbreaks. Limited data exist about the PVL content of S. aureus strains in Turkey. In this multicentre study, we aimed to assess the PVL positivity and antimicrobial susceptibilities of S. aureus isolates recovered from skin and soft tissue samples of both community and nosocomial origin in the study period, 2007-08. METHODS: Two hundred and forty-two [92 community-acquired (CA) and 150 hospital-acquired (HA)] isolates were included in the study. Analysis of mecA and PVL was carried out using PCR. All isolates underwent susceptibility testing according to the CLSI. RESULTS: Out of 242 isolates, 77 were mecA positive. PVL was not found among methicillin-resistant S. aureus (MRSA) isolates, but 8 (5.3%) HA methicillin-susceptible S. aureus (MSSA) and 14 (15.2%) CA-MSSA, mostly isolated from furuncles (71.4%), were positive for PVL. Among PVL-positive strains, the penicillin resistance rate was 90.9%. Low resistance rates, <10%, were detected for erythromycin, fusidic acid and co-trimoxazole. PVL-positive strains showed higher rates of susceptibility to erythromycin, gentamicin and rifampicin than negative isolates. CONCLUSIONS: Based on the findings of this study, infection related to PVL-carrying CA-MRSA is not at an alarmingly high level, but population-based surveillance studies should be done to determine the real status.