-
Cell Host & Microbe Jan 2019Neonates are highly susceptible to infection with enteric pathogens, but the underlying mechanisms are not resolved. We show that neonatal chick colonization with...
Neonates are highly susceptible to infection with enteric pathogens, but the underlying mechanisms are not resolved. We show that neonatal chick colonization with Salmonella enterica serovar Enteritidis requires a virulence-factor-dependent increase in epithelial oxygenation, which drives pathogen expansion by aerobic respiration. Co-infection experiments with an Escherichia coli strain carrying an oxygen-sensitive reporter suggest that S. Enteritidis competes with commensal Enterobacteriaceae for oxygen. A combination of Enterobacteriaceae and spore-forming bacteria, but not colonization with either community alone, confers colonization resistance against S. Enteritidis in neonatal chicks, phenocopying germ-free mice associated with adult chicken microbiota. Combining spore-forming bacteria with a probiotic E. coli isolate protects germ-free mice from pathogen colonization, but the protection is lost when the ability to respire oxygen under micro-aerophilic conditions is genetically ablated in E. coli. These results suggest that commensal Enterobacteriaceae contribute to colonization resistance by competing with S. Enteritidis for oxygen, a resource critical for pathogen expansion.
Topics: Animals; Animals, Newborn; Cecum; Chickens; Coinfection; Enterobacteriaceae; Escherichia coli; Female; Gastrointestinal Microbiome; Male; Mice; Oxygen; Probiotics; Salmonella; Salmonella Infections, Animal; Salmonella enteritidis; Spores, Bacterial; Symbiosis; Virulence Factors
PubMed: 30629913
DOI: 10.1016/j.chom.2018.12.003 -
International Journal of Antimicrobial... Sep 2017The aim of this study was to evaluate wastewater for carbapenemase-producing Enterobacteriaceae (CPE) and 16S rRNA methylase-producing Gram-negative bacteria (MPB) and...
The aim of this study was to evaluate wastewater for carbapenemase-producing Enterobacteriaceae (CPE) and 16S rRNA methylase-producing Gram-negative bacteria (MPB) and to assess their occurrence following wastewater treatment. Wastewater samples were collected between June 2015 and March 2016 in the sewage network of the city of Basel (Switzerland) from sites located before and after influx of wastewater from the hospital into the sewage network. Samples were also obtained from the influent and effluent of the receiving wastewater treatment plant. Samples were screened for CPE and MPB using selective media. Escherichia coli and Klebsiella pneumoniae were typed by multilocus sequence typing (MLST). Carbapenemase and 16S rRNA methylase genes were identified by PCR and sequencing. Resistance profiles were determined by the disk diffusion test and Etest. The occurrence of CPE and MPB was increased downstream of hospital wastewater influx. Of 49 CPE isolates, 9 belonged to OXA-48-producing E. coli clone D:ST38, 7 were OXA-48-producing Citrobacter freundii, and 6 were KPC-2- or OXA-48-producing K. pneumoniae belonging to clonal complex 258. NDM (NDM-1, -5 and -9) and VIM (VIM-1) producers were detected sporadically. MPB included ArmA- and RmtB-producing E. coli and Citrobacter spp. Isolates corresponding to strains from wastewater were detected in the effluent of the treatment plant. Conclusively, CPE and MPB, predominantly OXA-48-producing Enterobacteriaceae, are readily detected in wastewater, survive wastewater treatment and are released into the aquatic environment. OXA-48-producers may represent an emerging threat to public health and environmental integrity.
Topics: Bacterial Proteins; Bacteriological Techniques; Enterobacteriaceae; Multilocus Sequence Typing; Polymerase Chain Reaction; Sequence Analysis, DNA; Switzerland; Wastewater; beta-Lactamases; tRNA Methyltransferases
PubMed: 28668692
DOI: 10.1016/j.ijantimicag.2017.04.017 -
FEMS Microbiology Reviews May 2010Broad-spectrum β-lactamase genes (coding for extended-spectrum β-lactamases and AmpC β-lactamases) have been frequently demonstrated in the microbiota of... (Review)
Review
Broad-spectrum β-lactamase genes (coding for extended-spectrum β-lactamases and AmpC β-lactamases) have been frequently demonstrated in the microbiota of food-producing animals. This may pose a human health hazard as these genes may be present in zoonotic bacteria, which would cause a direct problem. They can also be present in commensals, which may act as a reservoir of resistance genes for pathogens causing disease both in humans and in animals. Broad-spectrum β-lactamase genes are frequently located on mobile genetic elements, such as plasmids, transposons and integrons, which often also carry additional resistance genes. This could limit treatment options for infections caused by broad-spectrum β-lactam-resistant microorganisms. This review addresses the growing burden of broad-spectrum β-lactam resistance among Enterobacteriaceae isolated from food, companion and wild animals worldwide. To explore the human health hazard, the diversity of broad-spectrum β-lactamases among Enterobacteriaceae derived from animals is compared with respect to their presence in human bacteria. Furthermore, the possibilities of the exchange of genes encoding broad-spectrum β-lactamases - including the exchange of the transposons and plasmids that serve as vehicles for these genes - between different ecosystems (human and animal) are discussed.
Topics: Animals; Bacteria; Enterobacteriaceae; Enterobacteriaceae Infections; Food Microbiology; Humans; Interspersed Repetitive Sequences; Locomotion; Plasmids; Public Health; Zoonoses; beta-Lactam Resistance; beta-Lactamases
PubMed: 20030731
DOI: 10.1111/j.1574-6976.2009.00198.x -
BMC Genomics May 2016Post-translational glycosylation of the flagellin protein is relatively common among Gram-negative bacteria, and has been linked to several phenotypes, including...
BACKGROUND
Post-translational glycosylation of the flagellin protein is relatively common among Gram-negative bacteria, and has been linked to several phenotypes, including flagellar biosynthesis and motility, biofilm formation, host immune evasion and manipulation and virulence. However to date, despite extensive physiological and genetic characterization, it has never been reported for the peritrichously flagellate Enterobacteriaceae.
RESULTS
Using comparative genomic approaches we analyzed 2,000 representative genomes of Enterobacteriaceae, and show that flagellin glycosylation islands are relatively common and extremely versatile among members of this family. Differences in the G + C content of the FGIs and the rest of the genome and the presence of mobile genetic elements provide evidence of horizontal gene transfer occurring within the FGI loci. These loci therefore encode highly variable flagellin glycan structures, with distinct sugar backbones, heavily substituted with formyl, methyl, acetyl, lipoyl and amino groups. Additionally, an N-lysine methylase, FliB, previously identified only in the enterobacterial pathogen Salmonella enterica, is relatively common among several distinct taxa within the family. These flagellin methylase island loci (FMIs), in contrast to the FGI loci, appear to be stably maintained within these diverse lineages.
CONCLUSIONS
The prevalence and versatility of flagellin modification loci, both glycosylation and methylation loci, suggests they play important biological roles among the Enterobacteriaceae.
Topics: Enterobacteriaceae; Flagella; Flagellin; Gene Transfer, Horizontal; Genes, Bacterial; Genetic Loci; Glycosylation; Phylogeny; Polysaccharides; Protein Processing, Post-Translational
PubMed: 27206480
DOI: 10.1186/s12864-016-2735-x -
Journal of Global Antimicrobial... Mar 2020The aim of this study was to investigate the occurrence of the newly described transferable colistin resistance gene mcr-9 in extended-spectrum β-lactamase...
OBJECTIVES
The aim of this study was to investigate the occurrence of the newly described transferable colistin resistance gene mcr-9 in extended-spectrum β-lactamase (ESBL)-producing clinical Enterobacteriaceae isolates from horses in Sweden.
METHODS
A total of 56 whole-genome sequenced ESBL-producing Enterobacteriaceae isolates from horses were subjected to in silico detection of antimicrobial resistance genes and identification of plasmid replicons types. The colistin minimum inhibitory concentration (MIC) for mcr-positive isolates was determined by broth microdilution. Relatedness between Enterobacteriaceae carrying mcr genes was determined by multilocus sequence typing (MLST) and core genome MLST.
RESULTS
Thirty ESBL-producing Enterobacteriaceae isolates from horses were positive for the colistin resistance gene mcr-9. These isolates included Enterobacter cloacae, Escherichia coli, Klebsiella oxytoca and Citrobacter freundii and belonged to diverse MLST sequence types within each species. Two of the mcr-9-containing isolates originated from the same horse. All mcr-9-positive isolates had colistin MICs below or equal to the EUCAST epidemiological cut-off value of 2 mg/L and were negative for the two potential regulatory genes qseB-like and qseC-like for mcr-9. Except for one isolate carrying only bla, all of the isolates carried bla and bla, and were all considered multidrug-resistant as they harboured genes encoding resistance to aminoglycosides, chloramphenicol, fosfomycin, macrolides, quinolones, sulfonamides, trimethoprim and tetracyclines. Plasmid replicon types IncHI2 and IncHI2A were detected in all mcr-9-positive isolates.
CONCLUSION
The occurrence of mcr-9 was common among clinical ESBL-producing Enterobacteriaceae isolates from horses in Sweden and was linked to the ESBL-encoding gene bla and plasmid replicon types IncHI2 and IncHI2A.
Topics: Animals; Bacterial Proteins; Colistin; Computer Simulation; Drug Resistance, Multiple, Bacterial; Enterobacteriaceae; Enterobacteriaceae Infections; High-Throughput Nucleotide Sequencing; Horse Diseases; Horses; Microbial Sensitivity Tests; Multilocus Sequence Typing; Plasmids; Sweden; Whole Genome Sequencing; beta-Lactamases
PubMed: 31494305
DOI: 10.1016/j.jgar.2019.08.007 -
Acta Microbiologica Et Immunologica... Mar 2017This study applied two phenotypic tests, namely "Carbapenemase Nordmann-Poirel" (CarbaNP) test and "Carbapenem Inactivation Method" (CIM), against the isolates carrying...
This study applied two phenotypic tests, namely "Carbapenemase Nordmann-Poirel" (CarbaNP) test and "Carbapenem Inactivation Method" (CIM), against the isolates carrying the carbapenem resistance genes. The study included 83 carbapenem-resistant Enterobacteriaceae isolates producing oxacillinase-48 (OXA-48) and 30 carbapenem-sensitive Enterobacteriaceae isolates. Out of the total isolates studied, 77 isolates (92.77%) were identified as Klebsiella pneumoniae and six isolates (7.23%) were identified as Escherichia coli by Matrix Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry. Polymerase chain reaction (PCR) method used to detect resistance genes found that 74 isolates (89.16%) produced OXA-48 carbapenemase, whereas nine isolates (10.84%) produced both OXA-48 and New Delhi metallo-beta-lactamase-1 (NDM-1). The isolates producing both OXA-48 and NDM-1 were found to be positive by both phenotypic tests. Among isolates carrying only bla gene alone, nine isolates (13.04%) for CarbaNP test and two isolates for CIM test (2.90%) displayed false negative results, respectively. The sensitivity of CarbaNP and CIM tests was found to be 89.16% and 97.59%, respectively, whereas the specificity was determined to be 100% for both tests. These findings suggest that CarbaNP and CIM tests are useful tools to identify the carbapenemase producers. Molecular methods like PCR are recommended to verify false negative tests predicted to have OXA-48 activity.
Topics: Anti-Bacterial Agents; Bacterial Proteins; Carbapenems; Enterobacteriaceae; Enterobacteriaceae Infections; Humans; Microbial Sensitivity Tests; beta-Lactamases
PubMed: 28357923
DOI: 10.1556/030.64.2017.009 -
PloS One 2017The first aim of this study was to evaluate the antimicrobial resistance of Enterobacteriaceae in different water environments of Guadeloupe and especially those...
OBJECTIVE
The first aim of this study was to evaluate the antimicrobial resistance of Enterobacteriaceae in different water environments of Guadeloupe and especially those impacted by waste water treatment plants (WWTP) effluents. The second objective was to characterize the genetic basis for antibiotic resistance of extended-spectrum beta-lactamase (ESBL) and AmpC beta-lactamase producing Enterobacteriaceae isolates (ESBLE and AmpCE).
METHODS
We have collected 70 surface waters (river and sea samples) impacted or not by WWTP and 18 waste waters from 2 WWTPs in 2012 and 2013. We i) determined the total and resistant bacterial counts and ii) tested isolated Enterobacteriaceae for their antimicrobial susceptibility. We also studied the genetic basis for antibiotic resistance of ESBLE and AmpCE, and the genetic background of Escherichia coli.
RESULTS
In rivers, contamination with Escherichia coli and antibiotic resistant coliforms (ARC) increased from the source to the mouth. Highest levels of river contamination with E. coli (9.26 x 105 MPN/100mL) and ARC (2.26 x 108 CFU/mL) were observed in surface water sampled near the discharge. A total of 246 Enterobacteriaceae strains resistant to antibiotics were isolated, mostly from waste waters and from river water collected near the discharge. Among these strains, 33 were Extended Spectrum Beta Lactamase (ESBLE) and 8 E. coli were AmpC beta-lactamase producers. All the ESBLE were isolated from waste waters or from river water collected near the discharge. The blaCTX-M gene was present in 29 of the 33 ESBLE strains, with 24 belonging to group 1. Numerous strains (68.7%) showed more than one acquired antibiotic resistance mechanism. E. coli strains belonged to different phylogenetic groups; among the B2 group, most strains belonged to the ST131 clone.
CONCLUSION
Our results demonstrated that many human activities can supply antibiotic-resistant bacteria in surface water. Nevertheless, WWTPs were the most important supplier of ESBLE in water environment of Guadeloupe.
Topics: Anti-Bacterial Agents; Colony Count, Microbial; Drug Resistance, Bacterial; Enterobacteriaceae; Guadeloupe; Microbial Sensitivity Tests; Phylogeny; Water Microbiology; Water Pollutants, Chemical
PubMed: 28253356
DOI: 10.1371/journal.pone.0173155 -
Acta Microbiologica Et Immunologica... Aug 2018Plasmid-mediated quinolone resistance (PMQR) determinants including, qnrA, qnrB, qnrC, qnrD, qnrS, aac(6')-Ib-cr, oqxAB, and qepA, were investigated in 214...
Plasmid-mediated quinolone resistance (PMQR) determinants including, qnrA, qnrB, qnrC, qnrD, qnrS, aac(6')-Ib-cr, oqxAB, and qepA, were investigated in 214 Enterobacteriaceae strains from urine clinical samples. Antimicrobial susceptibility testing for ciprofloxacin, ceftriaxone, and imipenem was performed by broth microdilution method. All strains were screened for PMQR genes by PCR. Virulence determinants, namely afa, pap, pil, sfa/foc, and kpsMT of eight Escherichia coli strains proven positive for at least one qnr gene, were investigated by PCR. All of the eight investigated strains carried the pil gene, showing that P fimbria is a common virulence determinant among qnr positive E. coli. Out of 214 tested strains, 38 yielded any PMQR determinant, altogether 45 genes were detected namely, 6 qnrA, 1 qnrB, 2 qnrD and 8 qnrS, 9 aac(6')-Ib-cr, and 19 oqxAB; however, neither qepA nor qnrC were detected. Notably, 18 Klebsiella spp., harbored oqxAB, nine E. coli were positive for qnrS and two Morganella morganii yielded qnrD resistance determinant. In this study, we demonstrated 17.7% prevalence of PMQR-positive Enterobacteriaceae and first reported qnrD-resistance determinant in Hungary. Altogether, 25 PMQR-positive strains were susceptible or low-level resistant to ciprofloxacin with minimum inhibitory concentration (MIC) between 0.06 and 1 mg/L, suggesting that prevalence of PMQR determinants is underestimated and screening among clinical isolates exhibiting reduced susceptibility is necessary. Fluoroquinolone resistance breakpoints of Enterobacteriaceae were revised in 2017 by European Committee of Antimicrobial Susceptibility Testing indicating ciprofloxacin susceptibility only until 0.25 mg/L MIC value.
Topics: Anti-Bacterial Agents; Bacterial Proteins; Drug Resistance, Bacterial; Enterobacteriaceae; Enterobacteriaceae Infections; Humans; Microbial Sensitivity Tests; Plasmids; Quinolones; Urinary Tract Infections; Urine
PubMed: 29471688
DOI: 10.1556/030.65.2018.012 -
Revista Da Sociedade Brasileira de... 2017In this study, we used phenotypic methods to screen carbapenem-resistant Enterobacteriaceae (CREs) and evaluated their antimicrobial sensitivity profile.
INTRODUCTION:
In this study, we used phenotypic methods to screen carbapenem-resistant Enterobacteriaceae (CREs) and evaluated their antimicrobial sensitivity profile.
METHODS:
One hundred and seventy-eight CREs were isolated at a university hospital in south Brazil in a one-year period. Samples were assessed using disk diffusion tests with inhibitors of β-lactamases such as phenylboronic acid (AFB), cloxacillin (CLOXA), and ethylenediaminetetraacetic acid (EDTA). Strains with differences in zone diameters ≥ 5mm for disks supplemented or not were considered producers of carbapenemases.
RESULTS:
Klebsiella pneumoniae was the most prevalent CRE, which appeared in 80.3% cases (n = 143). Among clinical materials, the rectal swab was responsible for 43.4% of the isolations (n = 62), followed by urine (18.9%; n = 27). Among the CREs identified in this study, the growth of 56.7% (n = 101) isolates, which were putative producers of Klebsiella pneumoniae carbapenemase (KPC), were inhibited by AFB, whereas 7.3% (n = 13) isolates were inhibited by both AFB and CLOXA and were considered as putative producers of plasmid-mediated AmpC; approximately 3.4% (n = 6) were inhibited by EDTA, which possibly produced metallo-β-lactamase. Lastly, 32.6% (n = 58) cases showed negative results for AFB, CLOXA, and EDTA sensitivity, and represented another class of β-lactamases and/or mechanism of resistance.
CONCLUSIONS:
Phenotypic screening of CREs is important for clinical laboratories that monitor outbreaks of resistant microbes. Phenotypic tests that use carbapenemase inhibitors and enhancers such as AFB, CLOXA, and EDTA are necessary since they are good screening methods for the detection of carbapenemases.
Topics: Anti-Bacterial Agents; Carbapenems; Enterobacteriaceae; Hospitals, University; Humans; Microbial Sensitivity Tests; Phenotype; beta-Lactam Resistance
PubMed: 28562752
DOI: 10.1590/0037-8682-0471-2016 -
Emerging Infectious Diseases Jun 2016For identification of polymyxin resistance in Enterobacteriaceae, we developed a rapid test that detects glucose metabolization associated with bacterial growth in the...
For identification of polymyxin resistance in Enterobacteriaceae, we developed a rapid test that detects glucose metabolization associated with bacterial growth in the presence of a defined concentration of colistin or polymyxin B. Formation of acid metabolites is evidenced by a color change (orange to yellow) of a pH indicator (red phenol). To evaluate the test, we used bacterial colonies of 135 isolates expressing various mechanisms of colistin resistance (intrinsic, chromosomally encoded, and plasmid-mediated MCR-1) and 65 colistin-susceptible isolates. Sensitivity and specificity were 99.3% and 95.4%, respectively, compared with the standard broth microdilution method. This new test is inexpensive, easy to perform, sensitive, specific, and can be completed in <2 hours. It could be useful in countries facing endemic spread of carbapenemase producers and for which polymyxins are last-resort drugs.
Topics: Anti-Bacterial Agents; Drug Resistance, Bacterial; Enterobacteriaceae; Enterobacteriaceae Infections; Genes, Bacterial; Genotype; Humans; Microbial Sensitivity Tests; Polymyxins
PubMed: 27191712
DOI: 10.3201/eid2206.151840