Determinants of urosepsis in Escherichia coli remain incompletely defined. Cyclomodulins (CMs) are a growing functional family of toxins that hijack the eukaryotic cell cycle. Four cyclomodulin types are actually known in E. coli: cytotoxic necrotizing factors (CNFs), cycle-inhibiting factor (Cif), cytolethal distending toxins (CDTs), and the pks-encoded toxin. In the present study, the distribution of CM-encoding genes and the functionality of these toxins were investigated in 197 E. coli strains isolated from patients with communityacquired urosepsis (n ‫؍‬ 146) and from uninfected subjects (n ‫؍‬ 51). This distribution was analyzed in relation to the phylogenetic background, clinical origin, and antibiotic resistance of the strains. It emerged from this study that strains harboring the pks island and the cnf1 gene (i) were strongly associated with the B2 phylogroup (P, <0.001), (ii) frequently harbored both toxin-encoded genes in phylogroup B2 (33%), and (iii) were predictive of a urosepsis origin (P, <0.001 to 0.005). However, the prevalences of the pks island among phylogroup B2 strains, in contrast to those of the cnf1 gene, were not significantly different between fecal and urosepsis groups, suggesting that the pks island is more important for the colonization process and the cnf1 gene for virulence. pks-or cnf1-harboring strains were significantly associated with susceptibility to antibiotics (amoxicillin, cotrimoxazole, and quinolones [P, <0.001 to 0.043]). Otherwise, only 6% and 1% of all strains harbored the cdtB and cif genes, respectively, with no particular distribution by phylogenetic background, antimicrobial susceptibility, or clinical origin.The bacterial species Escherichia coli comprises a wide diversity of strains belonging to the commensal intestinal flora of humans and warm-blooded animals. Among these strains, several pathogenic variants cause intestinal or extraintestinal infections in humans and animals (33). Population genetic studies based on multilocus enzyme electrophoresis and various DNA markers (10,20,44) classify the E. coli strains into four major phylogenetic groups (A, B1, B2, and D). The groups are diversely associated with certain ecological niches and propensities to cause disease.Extraintestinal pathogenic E. coli (ExPEC) strains are facultative pathogens that are not yet fully described. They are reported to belong mainly to phylogroups B2 and D, and they possess high numbers of virulence genes that belong to a flexible gene pool (43, 53). Among ExPEC strains, uropathogenic E. coli (UPEC) strains take advantage of host behavior and susceptibility by employing virulence factors that facilitate bacterial growth and persistence in the urinary tract (5, 28-30). Important virulence mechanisms are adhesion, invasion, subversion of host defenses, and direct interference with host cellular functions via secreted effectors (33,69).These effectors include the cyclomodulins (CMs), a functional class of toxins that hijack the cell cycle, a fundamental host cell process (48). In the ...

The chromogenic agar medium chromID ESBL (bioMé rieux) was compared with BLSE agar medium (AES) for selective isolation and presumptive identification of extended-spectrum b-lactamase (ESBL)-producing Enterobacteriaceae from clinical samples. A total of 765 samples (468 rectal swabs, 255 urine samples and 42 pulmonary aspirations) obtained from 547 patients was processed. All bacterial strains isolated on either medium were further characterized using biochemical tests, and ESBL producers were confirmed by synergy testing. Genetic characterization of ESBL genes was determined by PCR. A total of 33 ESBL-producing Enterobacteriaceae strains [Escherichia coli (n516), Klebsiella pneumoniae (n58), Enterobacter spp. (n53), Citrobacter spp. (n55) and Proteus mirabilis (n51)] was recovered. The sensitivity after 24 h incubation was 88 % for chromID ESBL and 85 % for BLSE agar. At 48 h, the sensitivity of chromID ESBL increased to 94 % and was higher than that obtained with BLSE agar. The positive predictive value at 24 h for chromID ESBL was 38.7 % [95 % confidence interval (95 % CI) 28.3 -50.2 %)], which was significantly higher than that for BLSE agar [15.4 %, 95 % CI 10.1 -21.5 %]. On both media, false-positive results were mostly due to Pseudomonas aeruginosa and to Enterobacteriaceae overproducing chromosomal cephalosporinase (Enterobacter spp.) or a chromosomal penicillinase (Klebsiella oxytoca). This study showed that chromID ESBL, a ready-to-use chromogenic selective medium, is sensitive and specific for rapid, presumptive identification of ESBL-producing Enterobacteriaceae. Its chromogenic properties and its selectivity are particularly useful in specimens containing resident associated flora.

SummaryDisruption of cell/ECM interactions resulting from uncontrolled pericellular proteolysis leads to detachment-induced cell apoptosis (anoikis), contributing to the morbid evolution of inflammatory vascular diseases. During cardiovascular infections, bacterial proteinases might induce vascular cells to enter a similar pathway. We focused on LasB, the predominant metalloproteinase secreted by the haematotropic pathogen Pseudomonas aeruginosa. While the exosecretome of the LasBdeficient pseudomonal strain PAO1lasBD had limited impact on human vascular cell adherence and viability, secretomes from the LasBexpressing reference strain, PAO1, or clinical isolates from patients with cardiac infection all induced anoikis, as did purified LasB. Immunofluorescence and/or immunoblotting analysis of heart valve myofibroblast cultures or whole tissue revealed an extensive, LasB-dependent degradation of ECM-associated fibronectin and vitronectin, that preceded cell de-adherence, whereas type I collagen showed limited degradation. Moreover, LasB produced a rapid endoproteolysis of the cell-associated urokinase receptor/uPAR, leaving a truncated receptor that is unable to support cell adherence and survival via interactions with vitronectin and integrins. Conversely, major myofibroblast integrins showed no or only minor alterations. Thus, among P. aeruginosa-secreted metalloproteinases, LasB can induce vascular cell anoikis through simultaneous proteolysis of ECM components and cell receptors, suggesting the uPAR-vitronectin axis as a major target in this process.