Between October 2001 and August 2002, 30 hospital patients became infected or colonised by a multiresistant (including to carbapenems) epidemic strain of Acinetobacter baumannii (AbMR) in a hospital outbreak. This study analysed the risk-factors associated with acquisition of this epidemic strain and investigated the prognosis of patients infected by AbMR, with the aim of elucidating factors which lead to mortality. A case-control study of the acquisition of AbMR in patients infected or colonised in the hospital outbreak was performed. Independent risk-factors leading to death were studied by logistic regression analysis. Multivariate analysis of the risk-factors for colonisation/infection with AbMR revealed an independent association with the presence of an arterial catheter (OR, 1.13; 95% CI, 1.03-1.25) and administration of imipenem as monotherapy (OR, 11.12; 95% CI, 2.33-53.09). Multivariate analysis of the prognostic features leading to mortality revealed a significant association with hypotension or shock (OR, 24.63; 95% CI, 1.56-387.56) at the time of bacterial isolation.

During the course of a molecular epidemiology study of mechanisms of antibiotic resistance in the area served by our hospital (516,000 inhabitants), we isolated the gene encoding CTX-M-14 ␤-lactamase. Thirty clinical strains (27 Escherichia coli and 3 Klebsiella pneumoniae isolates) with a phenotype of extended-spectrum ␤-lactamase were collected from January to October 2001 and studied for the presence of the CTX-M-14 ␤-lactamase gene. By isoelectric point determination, PCR, and nucleotide sequencing, we detected the presence of this gene in 17 E. coli strains belonging to 15 different genotypes (REP-PCR) causing infections in 17 different patients. Epidemiological studies based on medical records did not suggest any relationship between the patients infected with these E. coli strains and, interestingly, 7 of 30 patients harboring strains with extended-spectrum ␤-lactamases never had contact with the hospital environment before the clinical E. coli isolation. Conjugation experiments revealed that this gene was plasmid mediated in the 17 E. coli strains, and plasmid restriction fragment length polymorphisms showed 9 different patterns in the 17 E. coli strains. By PCR, the sequence of the tnpA transposase gene of the insert sequence ISEcp-1 was detected in all the plasmids harboring the CTX-M-14 gene. These results strongly suggest that plasmid dissemination between different E. coli strains in addition to a mobile element (transposon) around the ␤-lactamase gene may be involved in the spreading of the CTX-M-14 gene. This study reinforces the hypothesis that the epidemiology of the prevalence of the ␤-lactamase genes is changing and should alert the medical community to the increase in the emergence of the CTX-M ␤-lactamases worldwide.

Enterobacter cloacae is an emerging clinical pathogen that may be responsible for nosocomial infections. Management of these infections is often difficult, owing to the high frequency of strains that are resistant to disinfectants and antimicrobial agents in the clinical setting. Multidrug efflux pumps, especially those belonging to the resistance-nodulation-division family, play a major role as a mechanism of antimicrobial resistance in gram-negative pathogens. In the present study, we cloned and sequenced the genes encoding an AcrAcBTolC-like efflux pump from an E. cloacae clinical isolate (isolate EcDC64) showing a broad antibiotic resistance profile. Sequence analysis showed that the acrR, acrA, acrB, and tolC genes encode proteins that display 79.8%, 84%, 88%, and 82% amino acid identities with the respective homologues of Enterobacter aerogenes and are arranged in a similar pattern. Deletion of the acrA gene to yield an AcrA-deficient EcDC64 mutant (Ec⌬acrA) showed the involvement of AcrAB-TolC in multidrug resistance in E. cloacae. However, experiments with an efflux pump inhibitor suggested that additional efflux systems also play a role in antibiotic resistance. Investigation of several unrelated isolates of E. cloacae by PCR analysis revealed that the AcrAB system is apparently ubiquitous in this species.Multidrug efflux pumps, especially those belonging to the resistance-nodulation-division family, play a major role in establishing the "intrinsic or acquired" resistance of gram-negative bacteria to a wide range of toxic compounds, including antibiotics (20).A well-studied example is the AcrAB-TolC multidrug resistance (MDR) tripartite pump system of Escherichia coli, which confers resistance to a wide variety of lipophilic and amphiphilic compounds, including dyes, detergents, and antimicrobial agents such as ethidium bromide, crystal violet, sodium dodecyl sulfate, bile acids, tetracycline, chloramphenicol, fluoroquinolones, ␤-lactams, erythromycin, and fusidic acid (17, 18). The presence of similar systems has been reported for other members of Enterobacteriaceae (2,9,11,12,14,15,16,21,28).The species of Enterobacter that most commonly cause nosocomial infections are E. cloacae and E. aerogenes (24). The existence of an acrB-like gene (11) has previously been identified in E. cloacae, although none of the components of the efflux pump have been cloned.The objectives of the present study were (i) to characterize the genes encoding the AcrAB-TolC-like efflux pump of E. cloacae and (ii) to determine the involvement of this efflux pump in MDR in E. cloacae. The clinical strain used in the study was an MDR strain of E. cloacae (EcDC64) which overexpressed the AcrAB system and also overexpressed the chromosomal ampC gene and exhibited a drastic reduction of ompC gene expression.(These results were presented in part at the 45th Interscience Conference on Antimicrobial Agents and Chemotherapy [2a].) MATERIALS AND METHODSBacterial strains and growth media. The bacterial strains used in the study are listed i...

In total, 320 vaginal or rectal swabs were cultured on Granada medium (GM) or Group B Streptococcus Differential Agar (GBSDA), and were also inoculated into LIM broth (Todd-Hewitt broth supplemented with selective antibiotics), for detection of group B Streptococcus (GBS). Overall, GBS isolates were detected on 53 of the 320 swabs; 47 of these isolates grew on both GM and GBSDA, five only on GBSDA, and one only following subculture from LIM broth. GBSDA appears to be a valid alternative to GM for the growth of GBS isolates from pregnant women.

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Microbiological analysis of a urine sample from an outpatient with symptoms of urinary infection detected >10(5) CFU/mL urine of Salmonella enterica serotype Virchow with resistance to cefotaxime. Molecular analysis demonstrated the presence of the gene encoding CTX-M-10 beta-lactamase in this clinical isolate. This is the first report of this enzyme in Salmonella spp.

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