The cell-triggering properties of BCR, TCR and FcR depend on structurally related immunoreceptor tyrosine-based activation motifs (ITAMs). Fc gamma RIIB have no ITAM and do not trigger cell activation. When coaggregated to BCR, they inhibit B cell activation. We show here that, when coaggregated to these receptors, Fc gamma RIIB inhibit Fc epsilon RI-, Fc gamma RIIA-, and TCR-dependent cell activation. Inhibition also affected cell activation by single ITAMs, in isolated FcR or TCR subunits. The same tyrosine-based inhibitory motif (ITIM), which is highly conserved in murine and human Fc gamma RIIB and that was previously shown to inhibit BCR-dependent B cell activation, was required to regulate TCR- and FcR-dependent cell activation. Our findings endow Fc gamma RIIB, and thus IgG antibodies, with general immunoregulatory properties susceptible to act on all ITAM-containing receptors.

Rapid and accurate identification of enterococci at the species level is an essential task in clinical microbiology since these organisms have emerged as one of the leading causes of nosocomial infections worldwide. Vibrational spectroscopic techniques (infrared [IR] and Raman) could provide potential alternatives to conventional typing methods, because they are fast, easy to perform, and economical. We present a comparative study using phenotypic, genotypic, and vibrational spectroscopic techniques for typing a collection of 18 Enterococcus strains comprising six different species. Classification of the bacteria by Fourier transform (FT)-IR spectroscopy in combination with hierarchical cluster analysis revealed discrepancies for certain strains when compared with results obtained from automated phenotypic systems, such as API and MicroScan. Further diagnostic evaluation using genotypic methods-i.e., PCR of the species-specific ligase and glycopeptide resistance genes, which is limited to the identification of only four Enterococcus species and 16S RNA sequencing, the "gold standard" for identification of enterococci-confirmed the results obtained by the FT-IR classification. These results were later reproduced by three different laboratories, using confocal Raman microspectroscopy, FT-IR attenuated total reflectance spectroscopy, and FT-IR microspectroscopy, demonstrating the discriminative capacity and the reproducibility of the technique. It is concluded that vibrational spectroscopic techniques have great potential as routine methods in clinical microbiology.

All bloodstream strains, total 1463, isolated during a 1 month period in 105 hospitals representing all geographical areas in France were collected to study their antimicrobial susceptibility. The three major species were Escherichia coli, Staphylococcus aureus and coagulase-negative staphylococci. Among the 242 S. aureus, 87 were resistant to methicillin and among those 99% were resistant to ciprofloxacin, 11.5% to gentamicin, 1% to quinupristin/dalfopristin and 8% were heterogeneously resistant to vancomycin. Study of the methicillin-resistant S. aureus indicated that 12 clones had disseminated in French hospitals, six being heterogeneously resistant to vancomycin. Among the Streptococcus pneumoniae, 43% showed decreased susceptibility to the penicillins and 42% to erythromycin. One isolate was highly resistant to fluoroquinolones. Gentamicin, cefotaxime, ciprofloxacin and gatifloxacin resistance was rare in Enterobacteriaceae with 95% of strains susceptible. The incidence of extended-spectrum beta-lactamases was quite low. Moreover more than 25% of Pseudomonas aeruginosa strains were resistant to ciprofloxacin and gentamicin. The magnitude of antibiotic resistance in bloodstream isolates, in particular Gram-positive bacteria, emphasizes the importance of hospital control measures, rational prescribing policies and new vaccine strategies.

Among 10,872 isolates of Enterobacteriaceae from a nationwide study of 88 French hospitals in 2005, 169 (1.7%) expressed an extended-spectrum ␤-lactamase. The most prevalent species were Escherichia coli (48.5%), Enterobacter aerogenes (23.7%), and Klebsiella pneumoniae (14.8%). Molecular analysis underlined the polyclonal spread of CTX-M-expressing E. coli, primarily isolates of the CTX-M-1 subgroup.Resistance to extended-spectrum cephalosporins in Enterobacteriaceae can be associated with the production of extendedspectrum ␤-lactamases (ESBL) (11). Since the end of the 1990s, a new family of ESBL, the CTX-M-type ␤-lactamases, has spread worldwide. To date, over 60 CTX-M-type ␤-lactamases have been described and divided into five different clusters: CTX-M-1, CTX-M-2, CTX-M-8, CTX-M-9, and CTX-M-25 (2,17,20). Several local or regional studies indicate the emergence of CTX-M ␤-lactamases in France, but concurring data for the nation as a whole are lacking (1,9,(12)(13)(14)(15)(16). We have conducted a nationwide prospective study in 88 nonteaching hospitals affiliated with the Collège de Bactériologie-Virologie-Hygiène des Hôpitaux de France network to evaluate both (i) the prevalence of ESBL-producing Enterobacteriaceae by using phenotypic confirmatory tests and (ii) the prevalence and molecular epidemiology of CTX-M-harboring Enterobacteriaceae (5, 6).Bacterial isolates. All ESBL-producing Enterobacteriaceae isolates were collected from clinical samples during a 1-month period (October 2005). For patients with recurrent infections, only isolates from the first episodes were included. Bacterial identification and ESBL screening were performed by the participating institutions according to the recommendations of the Antibiogram Committee of the French Society of Microbiology (10). The data concerning the total number of Enterobacteriaceae isolates and all the ESBL-producing Enterobacteriaceae isolates were centralized at the Service d'Hygiène Hospitalière, Centre Hospitalier de Versailles.Quality controls. The following four E. coli isolates were submitted anonymously: a wild type, two isolates harboring an extended-spectrum TEM or CTX-M ␤-lactamase, and an isolate overexpressing a cephalosporinase. Analyses of the capacity of each participating institution to detect the ESBL phenotype were sent to the central laboratory.Identification and antimicrobial susceptibility testing. Analysis at the central laboratory confirmed the identification and ESBL production determined by the API 20E and VITEK 2 systems (bioMérieux, Marcy l'Etoile, France), the double-disc synergy test, the MicroScan ESBL plus ESBL confirmation panel (Dade Behring, Sacramento, CA), and the Etest ESBL (AB Biodisk, Piscataway, NJ). Non-␤-lactam antimicrobial susceptibility testing was performed by using disk diffusion according to the French guidelines (for nalidixic acid, ciprofloxacin, gentamicin, amikacin, and cotrimoxazole) (10).PCR amplification. bla CTX-M genes were amplified by using PCR, as described previously (9). The determination of su...

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Hyphenation of attenuated total reflection Fourier transform infrared spectroscopy and cluster analysis has been used to characterise a susceptible Escherichia coli K12 strain and the transeonjugants TEM-1, TEM-2, TEM-3, SHV-2, SHV-3, SHV-4. A good discrimination of the susceptible strain from the transeonjugants was obtained. Although a limited success was achieved in the differentiation of SHV and TEM phenotypes in general, results obtained with TEM-2 and SHV-3 were convincing. Spectral differences observed are ascribed to the global effects of the conjugation process, particularly their repercussions in the nucleic acids and carbohydrate absorbing regions, rather than to P-lactamase point-mutations.

We describe the isolation of Staphylococcus aureus isolates with glycopeptide heteroresistant subpopulation from 15 patients (11 with colonizations and 4 with infections) in a French hospital. Non of the patients were previously treated with glycopeptides. The 15 isolates belonged to 2 different pulsotypes unrelated to other methicillin-resistant S. aureus isolates from the same hospital.