Programme Hospitalier Recherche Clinique, Institut Pasteur, Inserm, French Public Health Agency.

A comparative study was designed to evaluate the identification (ID) and antimicrobial susceptibility testing (AST) performances of the BD Phoenix Automated Microbiology System (Becton Dickinson Diagnostic Systems [BD], Pont de Claix, France). A total of 305 single clinical isolates were collected, and comparisons were made with routine manual methods in use in our microbiology laboratories. The percentages of correct IDs were 93.3, 89.4, 91.8, and 85.7% for enterobacteria, nonfermenting gram-negative bacilli, staphylococci, and streptococci-enterococci, respectively. The median ID time was 3 h, and the median time for AST was 10 h 30 min. AST results showed variable percentages of errors for the different antibiotics. None of the enterobacteria and 0.3% of Pseudomonas aeruginosa isolates showed a very major error (VME). Only one strain of Staphylococcus aureus showed a VME with oxacillin. We demonstrate here the efficiency of the Phoenix system, which can be used for the majority of strains encountered in a university-based laboratory, for ID and AST.Automation in microbiology is not an easy task because microbiology is still a discipline that requires input from laboratory staff for the interpretation of results. This is specifically the case for bacterial identification (ID) and detection of antibiotic resistance, since microbiologists are often able to identify a bacterium and its resistance phenotype on the basis of only a few parameters. However, biochemical ID and susceptibility testing require 24 h to be readable. Several factors favor the use of automatic systems in the microbiology laboratory. Reproducibility, the ability to track results, the availability of results within one working day, and reduced amounts of contaminated waste represent the main reasons. An added advantage includes an automatic connection to the laboratory informatics software, allowing better management of technician staff, an easier validation for the microbiologist with the help of an expert system, and the opportunity for the clinician to obtain partial or complete results faster, thus improving patient management. Over the last 20 years, a variety of automated systems for ID and antimicrobial susceptibility testing (AST) have been developed (12,13,16,17,27,33,35,(36)(37)(38)(39)(40)(41)43). These automated technologies allowed for the very first time complete management of ID and AST, requiring technical staff to perform only one dilution from an agar plate culture. For example, the Vitek 2 (bioMérieux, Marcy l'Étoile, France) and the BD Phoenix (Becton Dickinson Diagnostic Systems [BD], Pont de Claix, France) are new systems that automatically perform ID and AST on a manually prepared inoculum (1, 3, 6, 9, 10, 14, 15, 18, 19, 22-25, 31, 42). Both designs possess an advanced expert system and have a potential impact on the workflow of a clinical laboratory for a typical hospital. Moreover, rapid ID and AST can have a significant impact on the management of infections, especially those caused by antibiotic-resistant bacteria ...

The prevalence of ESBL-EC bacteraemia has been increasing dramatically. Previous colonization with ESBL-EC was a strong risk factor for ESBL-EC bacteraemia. More inadequate initial antimicrobial therapy was noted in the ESBL-EC group, but mortality and length of hospital stay were not significantly different from those of patients with non-ESBL-EC bacteraemia.

Nine clinical isolates of Enterobacteriaceae (six Escherichia coli and three Proteus mirabilis) isolated in three Parisian hospitals between 1989 and 2000 showed a particular extended-spectrum cephalosporin-resistance profile characterized by resistance to cefotaxime and aztreonam but not to ceftazidime. CTX-M-1, CTX-M-2, CTX-M-9, CTX-M-14 and two novel plasmid-mediated CTX-M beta-lactamases (CTX-M-20, and CTX-M-21) were identified by polymerase chain reaction and isoelectric focusing (pI>8) and were associated in eight cases with TEM-1 (pI=5.4) or TEM-2 (pI=5.6) beta-lactamases. We used internal ISEcp1 and IS26 forward primers and the CTX-M consensus reverse primer to characterize the CTX-M beta-lactamase promoter regions and showed their high degree of structure diversity. We found upstream of some bla(CTX-M) genes, a 266-bp sequence 100% identical to the sequence upstream of the Kluyvera ascorbata beta-lactamase gene, suggesting that this chromosomal enzyme is the progenitor of the CTX-M-2/5 cluster.