Impact of the inoculum size on the activity of the aztreonam-avibactam combination in a murine model of peritonitis due to expressing CTX-M-15 and NDM-1.

The combination of aztreonam (ATM) and avibactam (AVI) is an attractive option to treat infections caused by extended spectrum β-lactamase plus NDM-1-producing . Since ATM activity was shown to be severely impacted by an increase in the inoculum size , we wondered whether ATM-AVI activity could be impaired in high-inoculum infections. We analyzed the impact of the inoculum size on ATM-AVI activity and in a murine model of peritonitis due to susceptible CFT073-pTOPO and its isogenic derivatives producing NDM-1 ( CFT073-NDM1) and CTX-M-15 plus NDM-1 ( CFT073-CTXM15-NDM1).

Faecal carriage of extended-spectrum β-lactamase-producing Escherichia coli in a remote region of Niger.

Objective: Whole genome sequencing (WGS) of extended-spectrum β-lactamase-producing Escherichia coli (ESBL-E. coli) in developing countries is lacking. Here we describe the population structure and molecular characteristics of ESBL-E.

Reduced Chlorhexidine Susceptibility Is Associated with Tetracycline Resistance Genes in Clinical Isolates of Escherichia coli.

Chlorhexidine is a widely used antiseptic in hospital and community health care. Decreased susceptibility to this compound has been recently described in Klebsiella pneumoniae and Pseudomonas aeruginosa, together with cross-resistance to colistin. Surprisingly, few data are available for Escherichia coli, the main species responsible for community and health care-associated infections.

Neurologic Complications of Infective Endocarditis: A Joint Model for a Septic Thromboembolism and Inflammatory Small Vessel Disease.

Objectives: Embolic events from vegetations are commonly accepted as the main mechanism involved in neurologic complications of infective endocarditis. The pathophysiology may imply other phenomena, including vasculitis. We aimed to define the cerebral lesion spectrum in an infective endocarditis rat model.

Temocillin breakpoints in pyelonephritis: evaluation in a murine model due to ESBL-producing Escherichia coli clinical isolates.

Background: Due to a spectrum restricted to Enterobacteriaceae and stability against ESBL and AmpC enzymes, temocillin is of major interest for the treatment of pyelonephritis. But there are still uncertainties about the optimal regimen and clinical breakpoints.

Objectives: To study in a murine model of pyelonephritis the activity of temocillin against Escherichia coli isolates with different MICs in order to evaluate clinical breakpoints.

Ceftriaxone promotes the emergence of AmpC-overproducing Enterobacteriaceae in gut microbiota from hospitalized patients.

Epidemiological data suggest that ceftriaxone may promote the emergence of commensal AmpC-overproducing Enterobacteriaceae because of a high biliary excretion. We tested this hypothesis in hospitalized patients either treated by ceftriaxone alone or receiving no antibiotics. Hospitalized patients with no previous antibiotics or hospitalization in the last 3 months, treated only with ceftriaxone, were prospectively included.

Bacterial size matters: Multiple mechanisms controlling septum cleavage and diplococcus formation are critical for the virulence of the opportunistic pathogen Enterococcus faecalis.

Enterococcus faecalis is an opportunistic pathogen frequently isolated in clinical settings. This organism is intrinsically resistant to several clinically relevant antibiotics and can transfer resistance to other pathogens. Although E.

Ecological impact of ciprofloxacin on commensal enterococci in healthy volunteers.

Background: The ecological impact of ciprofloxacin on commensal enterococci is unknown.

Methods: Forty-eight healthy volunteers received ciprofloxacin from day (D) 0 to D14; stools were collected on D7, D14 and D42. Fluoroquinolone-susceptible and -resistant enterococci (FQ-SE and FQ-RE) were detected and quantified by culture, and identified by MALDI-TOF MS.

Selection of Resistance to Clarithromycin in Mycobacterium abscessus Subspecies.

Mycobacterium abscessus is an emerging pathogen against which clarithromycin is the main drug used. Clinical failures are commonly observed and were first attributed to acquired mutations in rrl encoding 23S rRNA but were then attributed to the intrinsic production of the erm(41) 23S RNA methylase. Since strains of M.

Prospective Cohort Study of the Relative Abundance of Extended-Spectrum-Beta-Lactamase-Producing Escherichia coli in the Gut of Patients Admitted to Hospitals.

A total of 458 patients were prospectively included at hospital admission and screened for extended-spectrum-beta-lactamase-producing (ESBL) Escherichia coli carriage in 2007 and in 2010 to 2012. A 4-fold increase in ESBL carriage (3% to 12%), a 5-fold increase in numbers of community patients among ESBL carriers, and a higher number of multiple ESBL strains was found in the 2010 to 2012 period. ESBL E.

qnrA6 genetic environment and quinolone resistance conferred on Proteus mirabilis.

Objectives: To determine the genetic location and environment of the qnrA6 gene in Proteus mirabilis PS16 where it was first described and to characterize the quinolone resistance qnrA6 confers.

Methods: Transformation experiments and Southern blotting were performed for plasmid and genomic DNA of P. mirabilis PS16 to determine the qnrA6 location.

Comparative dynamics of the emergence of fluoroquinolone resistance in staphylococci from the nasal microbiota of patients treated with fluoroquinolones according to their environment.

Fluoroquinolone-resistant staphylococci (FQRS) are primarily selected in the nasal microbiota during fluoroquinolone (FQ) treatment. To gain insight into the dynamics of the emergence of FQRS, 49 hospitalised patients (HPs) and 62 community patients (CPs) treated with FQs were studied. Nasal swabs were collected before (T0), at the end of (T1) and 1 month after (T2) FQ treatment.

Emergence of quinolone resistance in the microbiota of hospitalized patients treated or not with a fluoroquinolone.

Background: Quinolone resistance is a major global clinical problem. It primarily emerges in microbiota under selective pressure. Studies evaluating the incidence and risk factors for carrying quinolone-resistant bacteria in hospitalized patients treated with fluoroquinolones (FQs) are lacking.

Activity of fosfomycin alone or combined with cefoxitin in vitro and in vivo in a murine model of urinary tract infection due to Escherichia coli harbouring CTX-M-15-type extended-spectrum β-lactamase.

The efficacy of fosfomycin alone or combined with cefoxitin was investigated in vitro and in a murine model of urinary tract infection due to susceptible Escherichia coli CFT073-RR and its transconjugant CFT073-RR Tc (pblaCTX-M-15) harbouring a plasmid carrying the blaCTX-M-15 gene. In vitro, the combination of cefoxitin and fosfomycin was synergistic and bactericidal and prevented the emergence of fosfomycin-resistant mutants of CFT073-RR and CFT073-RR Tc (pblaCTX-M-15) that were selected with fosfomycin alone. In vivo, the combination conferred an advantage in terms of kidney sterilisation of mice infected with either strain compared with fosfomycin monotherapy.

Trend of plasmid-mediated quinolone resistance genes at the Children's Hospital in Tunisia.

The prevalence of plasmid-mediated quinolone resistance genes [qnr, aac(6')-Ib-cr and qepA] was sought among Enterobacteriaceae strains obtained from the Children's Hospital of Tunis (Tunisia). Non-duplicate isolates (n = 278) with resistance to extended-spectrum cephalosporins and collected in 2003, 2007, 2008 and 2009 were screened for qnr genes. Forty (14.

Predominant role of host proteases in myocardial damage associated with infectious endocarditis induced by Enterococcus faecalis in a rat model.

Infective endocarditis (IE) remains a life-threatening infectious disease with high morbidity and mortality. The objectives of the present study are to assess the host proteolytic activities of the vegetations and their cytotoxic potential in a rat model of experimental IE. Rats were infected with a strain of Enterococcus faecalis of particularly low virulence and weak protease expression.

Diversity of individual dynamic patterns of emergence of resistance to quinolones in Escherichia coli from the fecal flora of healthy volunteers exposed to ciprofloxacin.

Background: Emergence of quinolone-resistant Escherichia coli (QREC) is an increasing clinical challenge mostly originating in fecal microbiota. The dynamics of the emergence of QREC in feces from individuals exposed to ciprofloxacin is unknown.

Methods: A total of 48 healthy volunteers received oral ciprofloxacin for 14 days.