Alix Pantel

Epidemiology of carbapenemase-producing Enterobacteriaceae and Acinetobacter baumannii in Mediterranean countries.

The emergence and global spread of carbapenemase-producing Enterobacteriaceae and Acinetobacter baumannii are of great concern to health services worldwide. These β-lactamases hydrolyse almost all β-lactams, are plasmid-encoded, and are easily transferable among bacterial species. They are mostly of the KPC, VIM, IMP, NDM, and OXA-48 types. Their current extensive spread worldwide in Enterobacteriaceae is an important source of concern. Infections caused by these bacteria have limited treatment options and have been associated with high mortality rates. Carbapenemase producers are mainly identified among Klebsiella pneumoniae, Escherichia coli, and A. baumannii and still mostly in hospital settings and rarely in the community. The Mediterranean region is of interest due to a great diversity and population mixing. The prevalence of carbapenemases is particularly high, with this area constituting one of the most important reservoirs. The types of carbapenemase vary among countries, partially depending on the population exchange relationship between the regions and the possible reservoirs of each carbapenemase. This review described the epidemiology of carbapenemases produced by enterobacteria and A. baumannii in this part of the world highlighting the worrisome situation and the need to screen and detect these enzymes to prevent and control their dissemination.

Incidence rates of carbapenemase-producing Enterobacteriaceae clinical isolates in France: a prospective nationwide study in 2011–12

OBJECTIVES To determine proportions and incidence rates of Enterobacteriaceae producing carbapenemase among those non-susceptible (NS) to carbapenems in France. METHODS From November 2011 to April 2012, 71 laboratories recorded non-duplicate Enterobacteriaceae clinical isolates NS to at least one carbapenem and the total number of isolates of the different species. Carbapenem MICs were determined by broth microdilution and the β-lactamase content by DNA microarray. RESULTS During the study period, the 71 laboratories identified 133 244 Enterobacteriaceae isolates, of which 846 (0.63%) were NS to at least one carbapenem. Carbapenem-NS isolates accounted for 0.07% (61/90 148) among Escherichia coli isolates, 1.1% (111/10 436) among Klebsiella pneumoniae, 8.2% (492/5971) among Enterobacter cloacae and 4.0% (84/2104) among Enterobacter aerogenes. Among the 541 available carbapenem-NS isolates, 222 (including 63 randomly selected E. cloacae) were further analysed after confirmation of carbapenem non-susceptibility. None of the Enterobacter spp. isolates produced carbapenemase. Among the other species, 28 isolates produced carbapenemases (22 OXA-48, 4 KPC and 2 NDM), accounting for an estimated proportion of carbapenemase-producing isolates of 0.08% for all species, 0.01% for E. coli and 0.27% for K. pneumoniae. The incidence-density rate in the participating hospitals was 0.0041 per 1000 hospital-days and the incidence rate was 0.0027 per 100 admissions. CONCLUSIONS The incidence-density rate of carbapenemase-producing isolates per 1000 hospital-days was low and 30-fold lower than that of carbapenem-NS isolates (0.125) and almost 300-fold lower than that of ESBL-producing isolates (1.104) in these French hospitals.

Mass spectrometry: a revolution in clinical microbiology?

Abstract Recently, different bacteriological laboratory interventions that decrease reporting time have been developed. These promising new broad-based techniques have merit, based on their ability to identify rapidly many bacteria, organisms difficult to grow or newly emerging strains, as well as their capacity to track disease transmission. The benefit of rapid reporting of identification and/or resistance of bacteria can greatly impact patient outcomes, with an improvement in the use of antibiotics, in the reduction of the emergence of multidrug resistant bacteria and in mortality rates. Different techniques revolve around mass spectrometry (MS) technology: matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS), PCR combined with electrospray ionization-mass spectrometry (PCR/ESI-MS), iPLEX MassArray system and other new evolutions combining different techniques. This report emphasizes the (r)evolution of these technologies in clinical microbiology.

French regional surveillance program of carbapenemase-producing Gram-negative bacilli: results from a 2-year period

In February 2011, the CARB-LR group was created as a sentinel laboratory-based surveillance network to control the emergence of carbapenem-resistant Gram-negative bacilli (CR GNB) in a French Southern Region. We report the epidemiological results of a 2-year study. All the Gram-negative bacilli isolates detected in the different labs (hospital and community settings) of a French Southern Region and with reduced susceptibility to ertapenem and/or imipenem were characterised with regard to antibiotic resistance, bla genes content, repetitive sequence-based polymerase chain reaction (rep-PCR) profiles and multilocus sequence typing (MLST). A total of 221 strains were analysed. Acinetobacter baumannii was the most prevalent carbapenemase-producing bacteria, with a majority of OXA-23 producers (n = 37). One isolate co-produced OXA-23 and OXA-58 enzymes. Klebsiella pneumoniae was the most frequent carbapenemase-producing Enterobacteriaceae (CPE) (OXA-48 producer: n = 29, KPC producer: n = 1), followed by Escherichia coli (OXA-48 producer: n = 8, KPC producer: n = 1) and Enterobacter cloacae (OXA-48 producer, n = 1). One isolate of Pseudomonas aeruginosa produced a VIM-1 carbapenemase. A clonal diversity of carbapenemase-producing K. pneumoniae and E. coli was noted with different MLSTs. On the other hand, almost all OXA-23-producing A. baumannii strains belonged to the widespread ST2/international clone II. The link between the detection of CR GNB and a foreign country was less obvious, suggesting the beginning of a local cross-transmission. The number of CR GNB cases in our French Southern Region has sharply increased very recently due to the diffusion of OXA-48 producers.

Pyomelanin‐producing Pseudomonas aeruginosa selected during chronic infections have a large chromosomal deletion which confers resistance to pyocins

When bacterial lineages make the transition from free-living to permanent association with hosts, they can undergo massive gene losses, for which the selective forces within host tissues are unknown. We identified here melanogenic clinical isolates of Pseudomonas aeruginosa with large chromosomal deletions (66 to 270 kbp) and characterized them to investigate how they were selected. When compared with their wild-type parents, melanogenic mutants (i) exhibited a lower fitness in growth conditions found in human tissues, such as hyperosmolarity and presence of aminoglycoside antibiotics, (ii) narrowed their metabolic spectrum with a growth disadvantage with particular carbon sources, including aromatic amino acids and acyclic terpenes, suggesting a reduction of metabolic flexibility. Despite an impaired fitness in rich media, melanogenic mutants can inhibit their wild-type parents and compete with them in coculture. Surprisingly, melanogenic mutants became highly resistant to two intraspecific toxins, the S-pyocins AP41 and S1. Our results suggest that pyocins produced within a population of infecting P. aeruginosa may have selected for bacterial mutants that underwent massive gene losses and that were adapted to the life in diverse bacterial communities in the human host. Intraspecific interactions may therefore be an important factor driving the continuing evolution of pathogens during host infections.

First Description of Two Sequence Type 2 Acinetobacter baumannii Isolates Carrying OXA-23 Carbapenemase in Pagellus acarne Fished from the Mediterranean Sea near Bejaia, Algeria

ABSTRACT To determine the occurrence of carbapenem-resistant Acinetobacter baumannii in fish fished from the Mediterranean Sea near the Bejaia coast (Algeria), we studied 300 gills and gut samples that had been randomly and prospectively collected during 1 year. After screening on selective agar media, using PCR arrays and whole-genome sequencing, we identified for the first time two OXA-23-producing A. baumannii strains belonging to the widespread sequence type 2 (ST2)/international clone II and harboring aminoglycoside-modifying enzymes [aac(6′)-Ib and aac(3′)-I genes].

OXA-48-like carbapenemases producing Enterobacteriaceae in different niches

The emergence of carbapenem-resistant enterobacterial species poses a serious threat to public health worldwide. OXA-48-type carbapenem-hydrolyzing class D β-lactamases are widely distributed among Enterobacteriaceae, with significant geographical differences. To date, 11 OXA-48-like variants have been identified, with classical OXA-48 being the most widespread. These enzymes show high-level hydrolytic activity against penicillins and low-level hydrolysis towards carbapenems. Since the first description of the OXA-48 carbapenemase in Turkey, bacterial strains producing the enzyme have been extensively reported in nosocomial and community outbreaks in many parts of the word, particularly in the Mediterranean area and European countries. The rapid spread of Enterobacteriaceae producing OXA-48-like enzymes in different ecosystems has become a serious issue recently. The number of reservoirs for such organisms is increasing, not only in hospitals, but also in the community, among animals (e.g., livestock, companion animals, and wildlife) and in the environment. This review aims to summarize the main characteristics of the OXA-48-type carbapenemases, covering genetic and enzymatic traits, their epidemiology, clonality and associated genes, correlation with extended-spectrum β-lactamases (ESBLs) or plasmidic AmpC (pAmpC) in different bacterial species worldwide.

Modulation of Membrane Influx and Efflux in Escherichia coli Sequence Type 131 Has an Impact on Bacterial Motility, Biofilm Formation, and Virulence in a Caenorhabditis elegans Model

ABSTRACT Energy-dependent efflux overexpression and altered outer membrane permeability (influx) can promote multidrug resistance (MDR). The present study clarifies the regulatory pathways that control membrane permeability in the pandemic clone Escherichia coli sequence type 131 (ST131) and evaluates the impact of efflux and influx modulations on biofilm formation, motility, and virulence in the Caenorhabditis elegans model. Mutants of two uropathogenic E. coli (UPEC) strains, MECB5 (ST131; H30-Rx) and CFT073 (ST73), as well as a fecal strain, S250 (ST131; H22), were in vitro selected using continuous subculture in subinhibitory concentrations of ertapenem (ETP), chloramphenicol (CMP), and cefoxitin (FOX). Mutations in genes known to control permeability were shown for the two UPEC strains: MECB5-FOX (deletion of 127 bp in marR; deletion of 1 bp and insertion of an IS1 element in acrR) and CFT073-CMP (a 1-bp deletion causing a premature stop in marR). We also demonstrated that efflux phenotypes in the mutants selected with CMP and FOX were related to the AcrAB-TolC pump, but also to other efflux systems. Alteration of membrane permeability, caused by underexpression of the two major porins, OmpF and OmpC, was shown in MECB5-ETP and mutants selected with FOX. Lastly, our findings suggest that efflux pump-overproducing isolates (CMP mutants) pose a serious threat in terms of virulence (significant reduction in worm median survival) and host colonization. Lack of porins (ETP and FOX mutants) led to a high level of antibiotic resistance in an H30-Rx subclone. Nevertheless, this adaptation created a physiological disadvantage (decreased motility and ability to form biofilm) associated with a low potential for virulence.

Carbapenemase-producing Enterobacteriaceae among pregnant women and newborns in Algeria: Prevalence, molecular characterization, maternal-neonatal transmission, and risk factors for carriage

&NA; The diffusion of carbapenemase‐producing Enterobacteriaceae (CPE) represents a worldwide public health problem. This study revealed that the prevalence of OXA‐48–producing enterobacteria was 4.6% (19/414) and 1.6% (7/422) in mothers and newborns, respectively, from 2 maternity units in Algeria. Previous hospital admission was an independent factor associated with an increased risk of CPE carriage in the mothers (P=.021). The low birth weight was significantly associated with this carriage in the newborns (P=.008). The screening of these bacteria is essential to prevent the dissemination of CPE.