[Comparison of routine use of two chromogenic media ChromID CPS (bioMérieux) and UriSelect4 (Bio-Rad) for the detection of Escherichia coli and major uropathogenics in urine]. / Comparaison de l'utilisation en routine de deux milieux chromogènes ChromID CPS (bioMérieux) et UriSelect4 (Bio-Rad) pour la détection d'Escherichia coli et des principaux uropathogènes dans les urines.

Escherichia coli is the most common bacterial cause of urinary tract infections. Its rapid and specific identification in urine samples represents a major challenge within the rendering results and optimizing the management of the patient. We aimed to compare the sensitivity and specificity of two commercially available chromogenic media for E. coli: ChromID CPS (Biomérieux) and UriSelect4 (Bio(-)Rad), without carrying out further tests. 99 consecutive and non-redundant urine samples considered to be infected were simultaneously plated onto blood agar and the two chromogenic media. Colony color and bacterial growth quantification were compared 18 and 48 hours after incubation. Bacteria were identified with mass spectrometry. A complementary analysis on 80 bacterial strains known to pose potential identification problems was performed. 43 urines samples grew E. coli, and 42 of them were pink-colored on the two chromogenic mediums, as expected (sensibility=97.7%). Growth quantification was significantly greater on blood agar than on chromogenic media (p<0.001).We noted specificity issues at the complementary analysis with the UriSelect4 medium: Citrobacter freundii and some strains of Citrobacter brakii, Enterobacter cloacae and Hafnia alvei were pink-colored, and could be misidentified as E. coli. ChromID CPS medium did not show such misidentification. In conclusion, the agar ChromID CPS proved to be greater than the UriSelect4 agar in our work in terms of specificity of direct identification of E. Coli, without the use of additional test.

High-resolution melting analysis for rapid characterization of qnr alleles in clinical isolates and detection of two novel alleles, qnrB25 and qnrB42.

OBJECTIVES: qnr genes are plasmid-mediated quinolone resistance genes. Five qnr families have been described with several alleles (7 alleles of qnrA, 53 alleles of qnrB, 1 allele of qnrC, 1 allele of qnrD and 6 alleles of qnrS). Their detection requires a PCR specific for each qnr family and further sequencing for allele characterization. METHODS: High-resolution melt curve analysis (HRMA) was coupled to multiplex and simplex real-time PCR assays for detection and characterization of qnrA, qnrB and qnrS alleles. The protocol was set using 27 reference strains harbouring the most frequent alleles and was applied to 55 clinical isolates unknown for qnr positivity. RESULTS: Out of the 27 reference strains tested, 21 alleles showed distinct profiles using HRMA: 6 qnrA, 12 qnrB and 3 qnrS. For the qnrB alleles showing similar profiles, we gathered them into four groups that were easily distinguished. For the alleles that we could not test, in silico analysis showed that they would be identified using the HRMA protocol set. Among the clinical isolates, 28 qnr-positive isolates were detected and the qnr allele was characterized as 8 qnrA1, 4 qnrB1, 5 qnrB2, 3 qnrB4, 1 qnrB8, 1 qnrB5, 3 qnrS1 and 1 qnrS2, with concordant results with PCR sequencing. Two new qnrB alleles were detected and distinguished using HMRA. They were further designated as qnrB25 and qnrB42. CONCLUSIONS: We developed an HRMA assay for characterizing the qnr alleles in clinical isolates. This high-throughput method can be used to screen a large number of isolates. This method allowed the detection of new qnrB alleles.

Rapid discrimination of environmental Vibrio by matrix-assisted laser desorption ionization time-of-flight mass spectrometry.

The aim of this study was to discriminate 30 Vibrio strains isolated from two wastewater treatment plants from Agadir, Morocco by two molecular typing methods, pulsed-field gel electrophoresis (PFGE) and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS). Out of the 30 strains of Vibrio examined in this study, 5 isolates could not be typed by PFGE and consistently appeared as a smear on the gel. In general, high genetic biodiversity among the Vibrio strains was found regardless to the isolation source. The results of MALDI TOF analysis show a high congruence of strain grouping demonstrating the accuracy and reliability of MALDI-TOF MS.

Staphylococcal Panton-Valentine leucocidin as a major virulence factor associated to furuncles.

Panton-Valentine Leucocidin (PVL), one of the ß-barrel pore-forming staphylococcal leucotoxins, is known to be associated to furuncles and some severe community pneumonia. However, it is still uncertain how many other virulence factors are also associated to furuncles and what the risk factors of furuncles are in immuno-compromised status of patients, especially the HIV (+) patients. In this paper, we use antigen immunoprecipitation and multiplex PCR approach to determine the presence of 19 toxins, 8 adhesion factors and the PFGE profiles associated to furuncles in three independent patient study groups of S. aureus (SA) isolates collected from the Cayenne General Hospital (French Guiana). The patient groups were made of: 16 isolates from HIV (-) patients, 9 from HIV (+) patients suffering from furuncles, and 30 control isolates from patients with diverse secondary infected dermatitis. Our data reveals that the majority (96%) of SA strains isolated from HIV patient-derived furuncles significantly produced PVL (p<10(-7)), whereas only 10% of SA strains produced this toxin in secondary infected dermatosis. A high prevalence of LukE-LukD-producing isolates (56 to 78%) was recorded in patient groups. Genes encoding clumping factor B, collagen- and laminin-binding proteins (clfB, cna, lbp, respectively) were markedly frequent (30 to 55%), without being associated to a specific group. Pulse field gel electrophoresis evidenced 24 overall pulsotypes, whereas the 25 PVL-producing isolates were distributed into 15 non clonal fingerprints. These pulsotypes were not specific PVL-producing isolates. PVL appears to be the major virulence factor associated to furuncles in Europe and in South America regardless of the immune status of the HIV patients.