Genetic characterisation of extended-spectrum β-lactamases inEscherichia coliisolated from retail chicken products including CTX-M-9 containing isolates: a food safety risk factor

Cross-Sectional Study for Detection and Risk Factor Analysis of ESBL-Producing Avian Pathogenic Escherichia coli Associated with Backyard Chickens in Pakistan

The increasing incidence of extended-spectrum β-lactamase (ESBL)-producing Escherichia (E.) coli in backyard chicken farming in Pakistan is of serious concern. This study aimed to assess the prevalence, antimicrobial resistance patterns and risk factors associated with ESBL avian pathogenic E. coli (APEC) isolated from backyard chickens in the Jhang district, Punjab, Pakistan. In total, 320 cloacal swabs were collected from four breeds of backyard chicken (Aseel, Golden, Misri and Necked Neck). ESBL E. coli were phenotypically identified using double disc synergy test (DDST) and corresponding genes were confirmed by multiplex polymerase chain reaction (mPCR). Out of the 320 samples, 164 (51.3%) were confirmed as E. coli, while 74 (45.1%) were characterized as ESBL E. coli. The frequency of isolation of ESBL E. coli was highest in Aseel chickens (35.1%). Of the 164 confirmed E. coli, 95.1%, 78.6%, 76.8%, 71.3%, 70.1%, 68.9%, 60.4% and 57.3% were resistant against tylosin, doxycycline, cefotaxime, enrofloxacin, colistin, trimethoprim/sulfamethoxazole, chloramphenicol and gentamicin, respectively. The ESBL gene types detected and their corresponding proportions were bla_CTX-M (54.1 %, 40/74), bla_TEM, (12.2%, 9/74) and co-existence (bla_CTX-M and bla_TEM) were shown in 33.8% (25/74). The bla_CTX-M gene sequence showed homology to bla_CTX-M-15 from clinical isolates. The mean multiple antibiotic resistance index (MARI) was found to be higher among ESBL E. coli (0.25) when compared to non-ESBL E. coli (0.17). Both free-range husbandry management system (p = 0.02, OR: 30.00, 95% CI = 1.47-611.79) and high antimicrobial usage in the last 6 months (p = 0.01, OR: 25.17, 95% CI = 1.81-348.71) were found significantly associated with isolation of ESBL-producing E. coli in the tested samples using binary logistic regression analysis. This study confirmed the potential of backyard chickens as a reservoir for ESBL E. coli in the Jhang district, Punjab, Pakistan.

Antibiotic Susceptibility Profiles and Resistance Mechanisms to β-Lactams and Polymyxins of Escherichia coli from Broilers Raised under Intensive and Extensive Production Systems

The intensive and extensive broiler production systems imply different veterinary interventions, including the use of antimicrobials. This study aimed to compare the antimicrobial susceptibility profiles of Escherichia coli isolated from both systems, characterize resistance mechanisms to β-lactams and polymyxins, and identify genetic elements such as integrons. E. coli isolates recovered from broiler cecal samples were assayed for antimicrobial susceptibility through the broth microdilution technique. The molecular characterization of acquired resistance mechanisms to β-lactams and colistin and the detection of integrons was performed by a multiplex PCR. For most antibiotics tested, the prevalence of reduced susceptibility is higher in commensal and extended-spectrum β-lactamases (ESBL)/AmpC producers from broilers raised in the intensive system, compared with those raised under extensive conditions. SHV-12 was the most common ESBL enzyme found in both production systems. Other ESBL variants such as CTX-M-1, CTX-M-55, CTX-M-14, CTX-M-32, CTX-M-9, TEM-52, and plasmid-encoded AmpC enzyme CMY-2 were also present. MCR-1 was identified in a colistin-resistant isolate from broilers raised under the intensive system. This study highlights the differences in E. coli antibiotic susceptibility from both production types and emphasizes that a great deal of work remains to decrease consumption and antimicrobial resistance levels.

Genomic insights of high-risk clones of ESBL-producing Escherichia coli isolated from community infections and commercial meat in southern Brazil

During a microbiological and genomic surveillance study conducted to investigate the molecular epidemiology of extended-spectrum β-lactamase (ESBL)-producing Escherichia coli from community-acquired urinary tract infections (UTI) and commercial meat samples, in a Brazilian city with a high occurrence of infections by ESBL-producing bacteria, we have identified the presence of CTX-M (-2, -14, -15, -24, -27 and -55)-producing E. coli of international clones ST38, ST117, ST131 and ST354. The ST131 was more prevalent in human samples, and worryingly the high-risk ST131-C1-M27 was identified in human infections for the first time. We also detected CTX-M-55-producing E. coli ST117 from meat samples (i.e., chicken and pork) and human infections. Moreover, the clinically relevant CTX-M-24-positive E. coli ST354 clone was detected for the first time in human samples. In summary, our results highlight a potential of commercialized meat as a reservoir of high-priority E. coli lineages in the community, whereas the identification of E. coli ST131-C1-M27 indicates that novel pandemic clones have emerged in Brazil, constituting a public health issue.

Prevalence and Characterization of ESBL/AmpC Producing Escherichia coli from Fresh Meat in Portugal

The present study aimed to characterize the extended-spectrum β-lactamases and plasmid-mediated AmpC β-lactamases (ESBL/PMAβ) among Escherichia coli producers isolated from beef, pork, and poultry meat collected at retail, in Portugal. A total of 638 meat samples were collected and inoculated on selective medium for the search of E. coli resistant to 3rd generation cephalosporins. Isolates were characterized by antimicrobial susceptibility testing, molecular assays targeting ESBL/AmpC, plasmid-mediated quinolone resistance (PMQR), and plasmid-mediated colistin resistance (PMCR) encoding genes. The highest frequency of E. coli non-wild type to 3rd generation cephalosporins and fluoroquinolones was observed in broiler meat (30.3% and 93.3%, respectively). Overall, a diversity of acquired resistance mechanisms, were detected: bla_ESBL [bla_CTX-M-1 (n = 19), bla_CTX-M-15 (n = 4), bla_CTX-M-32 (n = 12), bla_CTX-M-55 (n = 8), bla_CTX-M-65 (n = 4), bla_CTX-M-27 (n = 2), bla_CTX-M-9 (n = 1), bla_CTX-M-14 (n = 11), bla_SHV-12 (n = 27), bla_TEM-52 (n = 1)], bla_PMAβ [bla_CMY-2 (n = 8)], PMQR [qnrB (n = 27), qnrS (n = 21) and aac(6')-Ib-type (n = 4)] and PMCR [mcr-1 (n = 8)]. Our study highlights that consumers may be exposed through the food chain to multidrug-resistant E. coli carrying diverse plasmid-mediated antimicrobial resistance genes, posing a great hazard to food safety and a public health risk.

Dissemination of antibiotic resistance genes (ARGs) via integrons in Escherichia coli: A risk to human health

With the induction of various emerging environmental contaminants such as antibiotic resistance genes (ARGs), environment is considered as a key indicator for the spread of antimicrobial resistance (AMR). As such, the ARGs mediated environmental pollution raises a significant public health concern worldwide. Among various genetic mechanisms that are involved in the dissemination of ARGs, integrons play a vital role in the dissemination of ARGs. Integrons are mobile genetic elements that can capture and spread ARGs among environmental settings via transmissible plasmids and transposons. Most of the ARGs are found in Gram-negative bacteria and are primarily studied for their potential role in antibiotic resistance in clinical settings. As one of the most common microorganisms, Escherichia coli (E. coli) is widely studied as an indicator carrying drug-resistant genes, so this article aims to provide an in-depth study on the spread of ARGs via integrons associated with E. coli outside clinical settings and highlight their potential role as environmental contaminants. It also focuses on multiple but related aspects that do facilitate environmental pollution, i.e. ARGs from animal sources, water treatment plants situated at or near animal farms, agriculture fields, wild birds and animals. We believe that this updated study with summarized text, will facilitate the readers to understand the primary mechanisms as well as a variety of factors involved in the transmission and spread of ARGs among animals, humans, and the environment.

Superbugs in the supermarket? Assessing the rate of contamination with third-generation cephalosporin-resistant gram-negative bacteria in fresh Australian pork and chicken

Background

Antibiotic misuse in food-producing animals is potentially associated with human acquisition of multidrug-resistant (MDR; resistance to ≥ 3 drug classes) bacteria via the food chain. We aimed to determine if MDR Gram-negative (GNB) organisms are present in fresh Australian chicken and pork products.

Methods

We sampled raw, chicken drumsticks (CD) and pork ribs (PR) from 30 local supermarkets/butchers across Melbourne on two occasions. Specimens were sub-cultured onto selective media for third-generation cephalosporin-resistant (3GCR) GNBs, with species identification and antibiotic susceptibility determined for all unique colonies. Isolates were assessed by PCR for SHV, TEM, CTX-M, AmpC and carbapenemase genes (encoding IMP, VIM, KPC, OXA-48, NDM).

Results

From 120 specimens (60 CD, 60 PR), 112 (93%) grew a 3GCR-GNB (n = 164 isolates; 86 CD, 78 PR); common species were Acinetobacter baumannii (37%), Pseudomonas aeruginosa (13%) and Serratia fonticola (12%), but only one E. coli isolate. Fifty-nine (36%) had evidence of 3GCR alone, 93/163 (57%) displayed 3GCR plus resistance to one additional antibiotic class, and 9/163 (6%) were 3GCR plus resistance to two additional classes. Of 158 DNA specimens, all were negative for ESBL/carbapenemase genes, except 23 (15%) which were positive for AmpC, with 22/23 considered to be inherently chromosomal, but the sole E. coli isolate contained a plasmid-mediated CMY-2 AmpC.

Conclusions

We found low rates of MDR-GNBs in Australian chicken and pork meat, but potential 3GCR-GNBs are common (93% specimens). Testing programs that only assess for E. coli are likely to severely underestimate the diversity of 3GCR organisms in fresh meat.

Genotypic characterization of ESBL-producing E. coli from imported meat in South Korea

Twenty extended-spectrum β-lactamase (ESBL)-producing E. coli strains were isolated from imported meat in South Korea. ESBL strains of E. coli were detected in chicken (14/20) more often than in pork (6/20) and beef (0/20); the highest number (12/20) was detected in Brazilian meats. The bla_CTX-M genes were predominant in meats from many countries. E. coli from pork imported from France produced the bla_CTX-M-58 enzyme, which has never been documented previously in ESBL-producing bacteria from clinical or environmental sources. Additionally, the coexistence of the bla_CTX-M-2 and bla_OXA-1 enzymes in EC12-5 isolate was found for the first time in an ESBL E. coli isolate. A rare bla_CTX-M type, bla_CTX-M-25, was found in 40% of ESBL E. coli isolates. Phenotypic susceptibility testing showed that E. coli isolates were resistant to up to eleven antibiotics, including ciprofloxacin. For the first time, a new combination in an integron gene cassette, aacA4-cmlA6-qacEΔ1, was found in an E. coli isolate from poultry imported from Brazil. Three E. coli ST117 isolates, from an avian pathogenic lineage producing CTX-M-94, harbored fimH, fyuA, iutA, papC, rfc, and traT virulence genes and were not susceptible to quinolones. For the first time, rfc and papG virulence factors were detected in ESBL E. coli strains isolated from meat products. Even though E. coli CC21 and CC22 were obtained from meats from the USA and Brazil, respectively, they had a similarity coefficient higher than 99% in rep-PCR and the same MLST type (ST117), phenotypic antibiotic resistance pattern, integron gene (qacEΔ1), and plasmid DNA profile. This study indicates that imported meat products may be a source of ESBL-producing E. coli strains in South Korea.

Extended-Spectrum ß-Lactamase, AmpC-Producing, and Fluoroquinolone-Resistant Escherichia coli in Retail Broiler Chicken Meat, Italy

BACKGROUND

Globally, antimicrobial drug-resistant Escherichia coli is among the most common etiological agents of invasive disease in humans. In Europe, increasing proportions of infections due to third-generation cephalosporins and/or fluoroquinolone-resistant extraintestinal pathogenic E. coli (ExPEC) strains are reported. E. coli from poultry are those more closely linked to human E. coli, but lack of reliable data makes it difficult to assess the attributable risk of different food sources. In the present study, our objective was to investigate the antimicrobial resistance profile, phylogenetic background, and virulence factors of E. coli isolates from broiler chicken meat sold at retail in Palermo, Italy.

MATERIALS AND METHODS

Isolation of multidrug resistant (MDR) E. coli was performed during April-December 2013 on a total of 163 chicken meat samples. Susceptibility to a panel of nine antimicrobial agents was determined. PCR assays were carried out to detect extended-spectrum β-lactamase (ESBL), plasmid-mediated AmpC β-lactamase, and plasmid-mediated quinolone resistance (PMQR) genes, phylogenetic group, and ExPEC-associated traits. A single nucleotide polymorphism (SNP) PCR was done to detect E. coli sequence type (ST)131.

RESULTS

One hundred thirty-four isolates from 109 meat samples were MDR. B1 was the most prevalent phylogenetic group (47.8%), followed by groups D (25.4%), A (22.3%), and B2 (4.5%). ESBLs and AmpC β-lactamases were detected by PCR in 132 (98.5%) and 15 (11.2%) isolates. PMQR determinants were detected in 122 (91%) isolates. Twenty-two MDR isolates met the molecular definition of ExPEC. SNP-PCR results confirmed that four B2 isolates were ST131. Enterobacterial Repetitive Intergenic Consensus sequence-PCR analysis showed a large heterogeneity with 55 unique profiles and 31 clusters including 2-4 isolates.

CONCLUSIONS

An alarmingly high prevalence of MDR E. coli from broiler chicken meat is evident in our geographic area. The ongoing use of antimicrobial drugs in livestock should be urgently restricted, particularly in the poultry sector.

Extended-spectrum β-lactamase-producing Enterobacteriaceae in hospital food: a risk assessment

OBJECTIVE

Determine the prevalence of extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae (ESBL-PE) contamination of food and colonization of food handlers in a hospital kitchen and compare retrieved ESBL-PE strains with patient isolates.

DESIGN

Cross-sectional study.

SETTING

A 2,200-bed tertiary care university hospital in Switzerland.

PARTICIPANTS

Food handlers.

METHODS

Raw and prepared food samples were obtained from the hospital kitchen, with a comparator group from local supermarkets. Fecal samples collected from food handlers and selectively pre-enriched homogenized food samples were inoculated onto selective chromogenic media. Phenotypic confirmation of ESBL production was performed using the double disk method. Representative ESBL-PE were characterized using polymerase chain reaction (PCR) and sequencing for blaCTX-M, blaSHV, and blaTEM genes, and Escherichia coli strains were typed using phylotyping, repetitive element palindromic PCR, and multilocus sequence typing. Meat samples were screened for antibiotic residues using liquid chromatography time-of-flight mass spectrometry.

RESULTS

Sixty (92%) of the raw chicken samples were ESBL-PE positive, including 30 (86%) of the hospital samples and all supermarket samples. No egg, beef, rabbit, or cooked chicken samples were ESBL-PE positive. No antibiotic residues were detected. Six (6.5%) of 93 food handlers were ESBL-PE carriers. ESBL-PE strains from chicken meat more commonly possessed blaCTX-M-1 and blaCTX-M-2, whereas blaCTX-M-14 and blaCTX-M-15 were predominant among strains of human origin. There was partial overlap in the sequence type of E. coli strains of chicken and human origin. No E. coli ST131 strains or blaCTX-M-15 genes were isolated from meat.

CONCLUSIONS

Although there is significant ESBL-PE contamination of delivered chicken meat, current preventive strategies minimize risks to food handlers, hospital staff, and patients.

Extended-spectrum β-lactamase-producing Escherichia coli isolated from poultry: a review of current problems, illustrated with some laboratory findings

Extended-spectrum β-lactamase (ESBL)-producing Escherichia coli has been documented in humans as well as in food-producing birds, including chickens, and for unknown reasons the prevalence has increased significantly during the last decade. With E. coli as a major opportunistic pathogen in chickens and with a potential for zoonotic transfer to human beings, ESBL-producing E. coli represents a major risk both to poultry production and to human health. This review presents some of the current problems with ESBL-producing E. coli in relation to poultry production, with a focus on chickens. To illustrate issues in relation to screening and typing, two case studies are included where one collection of ESBL-producing E. coli isolates was obtained from asymptomatic carrier chickens while the other was obtained from lesions in chickens. Pulsed-field gel electrophoresis and multi-locus sequence typing revealed a highly heterogeneous population of ESBL-producing E. coli. All isolates harboured between one and three large plasmids (>100 kb). Among isolates associated with asymptomatic chickens, the ESBL types SHV and TEM dominated, while CTX-M-1 dominated in disease-associated isolates. The isolates from diseased birds were occasionally of sequence types often associated with human infections, such as ST131. With improved tools to trace and screen for ESBL-producing E. coli at farm level, strategies can be selected that aim to reduce or eliminate the presence of ESBL-producing E. coli in poultry and poultry products meant for human consumption.

IncH-type plasmid harboring bla CTX-M-15, bla DHA-1, and qnrB4 genes recovered from animal isolates

The whole sequence of plasmid pENVA carrying the extended-spectrum β-lactamase gene blaCTX-M-15 was determined. It was identified from a series of clonally related Klebsiella pneumoniae sequence type 274 strains recovered from companion animals. This plasmid was 253,984 bp in size and harbored, in addition to blaCTX-M-15, a large array of genes encoding resistance to many antibiotic molecules, including β-lactams (blaTEM-1, blaDHA-1), aminoglycosides (aacA2, aadA1), tetracycline (tetA), quinolones (qnrB4), trimethoprim (dfrA15), and sulfonamides (two copies of sul1). In addition, genes encoding resistance to mercury, tellurium, nickel, and quaternary compounds were identified. It also carried genes encoding DNA damage protection and mutagenesis repair and a locus for a CRISPR system, which corresponds to an immune system involved in protection against bacteriophages and plasmids. Comparative analysis of the plasmid scaffold showed that it possessed a structure similar to that of only a single plasmid, which was pNDM-MAR encoding the carbapenemase NDM-1 and identified from human K. pneumoniae isolates. Both plasmids possessed two replicons, namely, those of IncFIB-like and IncHIB-like plasmids, which were significantly different from those previously characterized. The blaCTX-M-15 gene, together with the other antibiotic resistance genes, was part of a large module likely acquired through a transposition process. We characterized here a new plasmid type carrying the blaCTX-M-15 gene identified in a K. pneumoniae isolate of animal origin. The extent to which this plasmid type may spread efficiently and possibly further enhance the dissemination of blaCTX-M-15 among animal and human isolates remains to be determined.