Ertapenem Resistance of Escherichia coli

An ertapenem-resistant Escherichia coli isolate was recovered from peritoneal fluid in a patient who had been treated with imipenem/cilastatin for 10 days. Ertapenem resistance may be explained by a defect in the outer membrane protein and production of extended-spectrum β-lactamase CTX-M-2

MST : Il n’y a pas que le SIDA

National audienc

Matrix-assisted laser desorption ionization time-of-flight mass spectrometry for bacterial strain characterization

International audienceMatrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) has emerged as a new technique for rapid and effective bacterial species identification in clinical microbiology laboratories. Conventional bacterial identification is based essentially on biochemical tests and requires lengthy incubation procedures. By contrast, MALDI-TOF MS can identify bacterial species in a few minutes, directly from a freshly grown colony. Various approaches have been developed for bacterial identification and the efficacy of this method has been demonstrated in several studies. This technique should also be suitable for the classification of organisms to subspecies level and for the phenotypic detection of certain antibiotic resistance mechanisms, such as beta-lactamases production

Regulatory RNAs in the Less Studied Streptococcal Species: from Nomenclature to Identification

Streptococcal species are Gram-positive bacteria involved in severe and invasive diseases in humans and animals. Although this group includes different pathogenic species involved in life-threatening infections for humans, it also includes beneficial species, such as Streptococcus thermophilus, which is used in yogurt production. In bacteria virulence factors are controlled by various regulatory networks including regulatory RNAs. For clearness and to develop logical thinking, we start this review with a revision of regulatory RNAs nomenclature. Previous reviews are mostly dealing with Streptococcus pyogenes and Streptococcus pneumoniae regulatory RNAs. We especially focused our analysis on regulatory RNAs in Streptococcus agalactiae, Streptococcus mutans, Streptococcus thermophilus and other less studied Streptococcus species. Although S. agalactiae RNome remains largely unknown, sRNAs (small RNAs) are supposed to mediate regulation during environmental adaptation and host infection. In the case of S. mutans, sRNAs are suggested to be involved in competence regulation, carbohydrate metabolism and Toxin-Antitoxin systems. A new category of miRNA-size small RNAs (msRNAs) was also identified for the first time in this species. The analysis of S. thermophilus sRNome shows that many sRNAs are associated to the bacterial immune system known as CRISPR-Cas system. Only few of the other different Streptococcus species have been the subject of studies pointed toward the characterization of regulatory RNAs. Finally, understanding bacterial sRNome can constitute one step forward to the elaboration of new strategies in therapy such as substitution of antibiotics in the management of S. agalactiae neonatal infections, prevention of S. mutans dental caries or use of S. thermophilus CRISPR-Cas system in genome editing applications

An Inventory of CiaR-Dependent Small Regulatory RNAs in Streptococci

International audienceBacteria adapt to the different environments encountered by rapid and tightly controlled regulations involving complex networks. A first line of control is transcriptional with regulators such as two-component systems (TCSs) that respond to physical and chemical perturbations. It is followed by posttranscriptional regulations in which small regulatory RNAs (sRNAs) may affect RNA translation. Streptococci are opportunistic pathogens for humans and farm animals. The TCS CiaRH is highly conserved among this genus and crucial in bacterial survival under stressful conditions. In several streptococcal species, some sRNAs belong to the CiaRH regulon and are called csRNAs for cia-dependent sRNAs. In this review, we start by focusing on the Streptococcus species harboring a CiaRH TCS. Then the role of CiaRH in streptococcal pathogenesis is discussed in the context of recent studies. Finally, we give an overview of csRNAs and their functions in Streptococci with a focus on their importance in bacterial adaptation and virulence

Caractérisation de la flore vaginale au troisième trimestre de la grossesse

POITIERS-BU Médecine pharmacie (861942103) / SudocSudocFranceF

A tetracycline-inducible expression vector for Streptococcus agalactiae allowing controllable gene expression.

International audienceStreptococcus agalactiae is the principal cause of neonatal infections; however, for its study, genetic tools are scarce. We have developed pG+off, an expression vector with a tetracycline inducible promoter that allows a tightly-controllable gene expression in S. agalactiae. Using a reporter gene, we have shown that pG+off is characterized by tight repression under non-induced condition

Transcription des gènes neu et production de l'acide sialique par des souches de Streptococcus agalactiae représentatives du sérotype III

TOURS-BU Sciences Pharmacie (372612104) / SudocSudocFranceF

Sensibilité des bacilles gram négatifs multi-résistants au céfidérocol

Session : Agents antimicrobiens et résistanceInternational audienceObjectif : Le céfidérocol est une nouvelle céphalosporine conjuguée à un sidérophore. Ainsi, il peut se lier au fer libre extracellulaire permettant un transport actif de l’antibiotique. De plus, ce sidérophore protège la molécule de l’activité hydrolytique de la plupart des β-lactamases. Grâce à ce nouveau mécanisme d’action, le céfidérocol pourrait être une alternative en cas d’impasse thérapeutique pour les bacilles gram négatifs multi-résistants. Le but de cette étude est de déterminer la sensibilité des entérobactéries produisant des carbapénèmases, de Pseudomonas aeruginosa et de Stenotrophomonas maltophilia multi-résistants au céfidérocol.Méthode : La sensibilité au céfidérocol a été étudiée à l’aide de disque chargé à 30 microgrammes et interprétée d’après les diamètres critiques du CASFM 2021. Vingt-cinq souches ont été testées : 10 souches de P. aeruginosa multi-résistants (résistant à la ceftazidime et à l’imipénème), huit souches d’entérobactéries productrices de carbapénèmase (5 OXA-48 et 3 NDM) et sept souches de S. maltophilia résistant à la Ceftzadime ou à l’association Ticarcilline-acideclavulanique.Résultats : Vingt-et-une souches sur 25 (84%) étaient sensibles au céfidérocol :- 80% des P. aeruginoa,- 75% des entérobactéries productrices de carbapénèmases (une souche OXA-48 et une souche NDM présentaient une résistance au Céfidérocol)- 100% des S. maltophiliaConclusion : Quatre-vingt-quatre pour cent des souches sélectionnées étaient sensibles au céfidérocol. Cette molécule pourrait donc être utilisée comme antibiotique de dernier recours dans le traitement des patients atteints d’infections à bactéries à Gram négatif multi-résistantes. Toutefois, cette étude a été réalisée sur un faible nombre de souches. Des tests complémentaires seront nécessaires pour confirmer ces résultat

Beta-lactam induction of ISEcp1B-mediated mobilization of the naturally occurring bla(CTX-M) beta-lactamase gene of Kluyvera ascorbata.

International audienceISEcp1B is an insertion element associated with the emerging expanded-spectrum beta-lactamase bla(CTX-M) genes in Enterobacteriaceae. Because ISEcp1B-bla(CTX-M)positive strains may be identified from humans and animals, the ability of this insertion sequence to mobilize the bla(CTX-M-2) gene was tested from its progenitor Kluyvera ascorbata to study the effects of amoxicillin/clavulanic and cefquinome as enhancers of transposition. These beta-lactam molecules are administered parenterally to treat infected animals. ISEcp1B-mediated mobilization of the bla(CTX-M-2) gene from K. ascorbata to a plasmid location in Escherichia coli J53 was studied. Transposition assays were performed with overnight cultures with amoxicillin/clavulanic acid and cefquinome at concentrations expected to mimic those found in feces after parenteral administration (0.4-0.008 mg L(-1) and 0.32-0.064 mg L(-1), respectively). Amoxicillin/clavulanic acid and cefquinome did not modify the transposition frequency (1.85+/-1.7 x 10(-7)) whereas ceftazidime (0.5 mg L(-1)), used as a control, did (5.2+/-2.7 x 10(-5)). Therefore, it is likely that neither amoxicillin/clavulanic acid nor cefquinome concentrations as found in the gut flora may enhance mobilization of the bla(CTX-M) genes in Enterobacteriaceae