Presence and Transfer of Antimicrobial Resistance Determinants in Escherichia coli in Pigs, Pork, and Humans in Thailand and Lao PDR Border Provinces

Occurrence and molecular characteristics of antimicrobial resistance, virulence factors, and extended-spectrum β-lactamase (ESBL) producing Salmonella enterica and Escherichia coli isolated from the retail produce commodities in Bangkok, Thailand

The incidence of antimicrobial resistance (AMR) in the environment is often overlooked and leads to serious health threats under the One Health paradigm. Infection with extended-spectrum β-lactamase (ESBL) producing bacteria in humans and animals has been widely examined, with the mode of transmission routes such as food, water, and contact with a contaminated environment. The purpose of this study was to determine the occurrence and molecular characteristics of resistant Salmonella enterica (S. enterica) (n = 59) and Escherichia coli (E. coli) (n = 392) isolated from produce commodities collected from fresh markets and supermarkets in Bangkok, Thailand. In this study, the S. enterica isolates exhibited the highest prevalence of resistance to tetracycline (11.9%) and streptomycin (8.5%), while the E. coli isolates were predominantly resistant to tetracycline (22.5%), ampicillin (21.4%), and sulfamethoxazole (11.5%). Among isolates of S. enterica (6.8%) and E. coli (15.3%) were determined as multidrug resistant (MDR). The prevalence of ESBL-producing isolates was 5.1% and 1.0% in S. enterica and E. coli, respectively. A minority of S. enterica isolates, where a single isolate exclusively carried blaCTX-M-55 (n = 1), and another isolate harbored both blaCTX-M-55 and blaTEM-1 (n = 1); similarly, a minority of E. coli isolates contained blaCTX-M-55 (n = 2) and blaCTX-M-15 (n = 1). QnrS (11.9%) and blaTEM (20.2%) were the most common resistant genes found in S. enterica and E. coli, respectively. Nine isolates resistant to ciprofloxacin contained point mutations in gyrA and parC. In addition, the odds of resistance to tetracycline among isolates of S. enterica were positively associated with the co-occurrence of ampicillin resistance and the presence of tetB (P = 0.001), while the E. coli isolates were positively associated with ampicillin resistance, streptomycin resistance, and the presence of tetA (P < 0.0001) in this study. In summary, these findings demonstrate that fresh vegetables and fruits, such as cucumbers and tomatoes, can serve as an important source of foodborne AMR S. enterica and E. coli in the greater Bangkok area, especially given the popularity of these fresh commodities in Thai cuisine.

Comparative Genetic Characterization of Pathogenic Escherichia coli Isolated from Patients and Swine Suffering from Diarrhea in Korea

The aim of this study was to compare the virulence factors and antimicrobial resistance of the most common pathogenic Escherichia coli strains in swine and patients with diarrhea in Korea. We examined virulence genes and antimicrobial susceptibility in 85 and 61 E. coli strains isolated from swine and patients with diarrhea, respectively. The most prevalent pathogen in swine was enterotoxigenic E. coli (ETEC) (47.1%), followed by Shiga toxin-producing E. coli (STEC) (32.9%). Similarly, the majority of the patient isolates (50.8%) were proven to be STEC, the most common pathotype, followed by ETEC (23.0%). We found that swine isolates had significantly higher resistance than patient isolates, especially to fluoroquinolones (ciprofloxacin: 37.5% and 16.1%; norfloxacin: 29.7% and 16.1%, respectively). Additionally, sequence type (ST) 100 (swine: 21; patients: 4), ST 1 (swine: 21, patients: 2), ST 10 (swine: 8; patients: 6), ST 641 (swine: 3, patients: 2), and ST 88 (swine: 2, patients: 11) were detected in both swine and humans. In addition, we confirmed that isolates from swine and patients had similar virulence traits and were phylogenetically similar. According to these findings, swine and humans are susceptible to cross infection and the transfer of antimicrobial resistance.

Antimicrobial Resistance Profiles and Molecular Characteristics of Extended-Spectrum β-Lactamase-Producing Escherichia coli Isolated from Healthy Cattle and Pigs in Korea

Antimicrobial-resistant bacteria isolated from food animals pose a major health threat to the public on this planet. This study aimed to determine the susceptibility profiles of Escherichia coli isolated from cattle and pig fecal samples and investigate the molecular characteristics of extended-spectrum β-lactamase (ESBL)-producing E. coli using gene identification, conjugation, and Southern blot approach. Overall 293 E. coli were recovered from cattle (120 isolates) and pigs (173 isolates) in 7 provinces of Korea during 2017-2018. Ampicillin, chloramphenicol, streptomycin, and sulfisoxazole resistance rates were the highest in pigs' isolates (>60%, p ≤ 0.001) compared to that in cattle (3-39%). Multidrug resistance (MDR) was higher in pig isolates (73%) than in cattle (31%), and the MDR profile usually includes streptomycin, sulfisoxazole, and tetracycline. Resistance to critically important antimicrobials such as ceftiofur, colistin, and ciprofloxacin was higher in weaners than those from finishers in pigs. The qnrS gene was detected in 13% of the pig isolates. Eight isolates from pigs and one isolate from cattle were identified as ESBL-producers and ESBL genes belonged to bla_CTX-M-55 (n = 4), bla_CTX-M-14 (n = 3), and bla_CTX-M-65 (n = 2). Notably, the bla_CTX-M-65 and qnrS1 genes were found to be carried together in an identical plasmid (IncHI2) in two isolates from finisher pigs. The bla_CTX-M-carrying isolates belonged to phylogenetic groups B1 (n = 4), B2 (n = 2), A (n = 2), and D (n = 1). The bla_CTX-M genes and non-β-lactam resistance traits were transferred to the E. coli J53 recipient from seven bla_CTX-M-positive strains isolated from pigs. The bla_CTX-M genes belonged to the IncI1α, IncFII, and IncHI2 plasmids and are also associated with the ISEcp1, IS26, IS903, and orf477 elements. These findings suggested the possibility of bla_CTX-M-carrying E. coli transmission to humans through direct contact with cattle and pigs or contamination of food products.

Antimicrobial resistance, virulence genes, and phylogenetic characteristics of pathogenic Escherichia coli isolated from patients and swine suffering from diarrhea

Background

Escherichia (E.) coli causes colibacillosis in swine and humans, and is frequently associated with antimicrobial resistance. In this study we aimed to compare antimicrobial resistance, O-serogroups, virulence genes, and multi-locus sequence type of E. coli between isolates from pigs and patients suffering from diarrhea, and the most prevalent pathogenic E. coli strain from swine isolates in Korea.

Methods

We tested 64 and 50 E. coli strains from pigs and patients suffering from diarrhea for antimicrobial susceptibility test, virulence genes, O-serogroups, and multi-locus sequence typing.

Results

We confirmed that isolates from swine showed significantly higher resistance than from those from patients, especially to fluoroquinolone (ciprofloxacin: 37.5 and 10.0%; norfloxacin: 29.7 and 8.0%, respectively). Stx1 (46.0%) was most frequently detected in patients followed by stx2 (38.0%). There was no significant difference in stx2 (swine: 23.4%, patients: 38.0%). In isolates from patients, O157 (12.0%) was the most prevalent O-serogroup, and two isolates (3.1%) from pigs were confirmed to have O157. Additionally, sequence type (ST) 10 (swine: 6 isolates, patients: 2 isolates) and ST 88 (swine: 2 isolates, patients: 1 isolate) were simultaneously detected.

Conclusions

We found that both isolates from swine and human had the stx2 gene, which could cause severe disease. Moreover, antimicrobial resistance was significantly higher in pigs than in patients. These results suggest that pig could act as a reservoir in human infection and antimicrobial resistance could be transferred to human from pigs.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12866-022-02604-z.

Genomic characterization of antimicrobial resistance in mcr-carrying ESBL-producing Escherichia coli from pigs and humans

Whole-genome sequencing (WGS) was conducted to characterize mcr-carrying extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli (n=7). These E. coli isolates originated from two pigs (TH2 and TH3) and two humans (TH8 and TH9) from Thailand, and three pigs from Lao PDR (LA1, LA2 and LA3). Four E. coli sequence types/serotypes - ST6833/H20 (TH2 and TH3), ST48/O160:H40 (TH8 and TH9), ST5708/H45 (LA1) and ST10562/O148:H30 (LA2 and LA3) - were identified. The plasmid replicon type IncF was identified in all isolates. The point mutations Ser31Thr in PmrA and His2Arg in PmrB were found concurrently in all isolates (colistin MIC=4-8 µg ml^-1). LA1 contained up to five point mutations in PmrB, and the colistin MIC was not significantly different from that for the other isolates. All mcr-1.1 was located in the ISApl1-mcr-1-pap2 element, while all mcr-3.1 was located in the TnAs2-mcr-3.1-dgkA-ISKpn40 element. The mcr-3.1 and bla _CTX-M-55 genes were co-localized on the same plasmid, which concurrently contained cml, qnrS1 and tmrB. The bla _CTX-M-55 and mcr-3.1 genes were located on conjugative plasmids and could be transferred horizontally under selective pressure from ampicillin or colistin. In conclusion, comprehensive insights into the genomic information of ESBL-producing E. coli harbouring mcr were obtained. As mcr-carrying ESBL-producing E. coli were detected in pigs and humans, a holistic and multisectoral One Health approach is required to contain antimicrobial resistance (AMR).

Plasmid profile analysis of Escherichia coli and Salmonella enterica isolated from pigs, pork, and humans

This study aimed to determine the epidemiology and association of antimicrobial resistance (AMR) among Escherichia coli and Salmonella in Thailand. The E. coli (n = 1047) and Salmonella (n = 816) isolates from pigs, pork and humans were screened for 18 replicons including HI1, HI2, I1-γ, X, L/M, N, FIA, FIB, W, Y, P, FIC, A/C, T, FIIAs, F, K and B/O using polymerase chain reaction-based replicon typing. The E. coli (n = 26) and Salmonella (n = 3) isolates carrying IncF family replicons, ESBL and/or mcr genes were determined for FAB formula. IncF represented the major type of plasmids. Sixteen and eleven Inc groups were identified in E. coli (85.3%) and Salmonella (25.7%), respectively. The predominant replicon patterns between E. coli and Salmonella were IncK-F (23.7%) and IncF (46.2%). Significant correlations (P < 0.05) were observed between plasmid-replicon type and resistance phenotype. Plasmid replicon types were significantly different among sources of isolates and sampling periods. The most common FAB types between E. coli and Salmonella were F2:A-:B- (30.8%) and S1:A-:B- (66.7%), respectively. In conclusion, various plasmids present in E. coli and Salmonella. Responsible and prudent use of antimicrobials is suggested to reduce the selective pressures that favour the spread of AMR determinants. Further studies to understand the evolution of R plasmids and their contribution to the dissemination of AMR genes are warranted.

Characterisation of plasmids harbouring qnrA1, qnrS1, and qnrB4 in E. coli isolated in the Philippines from food-producing animals and their products

OBJECTIVES

Determinants showing plasmid-mediated quinolone resistance, which usually leads to antimicrobial ineffectiveness, have become an emerging clinical problem. In our previous study in the Philippines, a high prevalence of Qnr determinants was found in clinical samples and food-producing animals and their food products. However, no qnr-carrying plasmids have been investigated in animals or animal-derived foods. Hence, in the present, we aimed to characterise qnr-carrying plasmids in Escherichia coli isolated from the food supply chain.

METHODS

Plasmids from 44 qnr-positive isolates were assigned to incompatibility groups by PCR-based replicon typing, and the presence of β-lactamase-encoding genes were investigated by PCR. Localisation of qnr in plasmids was determined by S1-PFGE and Southern blot hybridisation. The transferability of qnr-carrying plasmids was examined by conjugation analysis.

RESULTS

Overall, 77.3% (95%CI = 62.2 - 88.5) of the isolates harbouring qnr determinants were positive for seven plasmid types, and 56.8% concurrently harboured bla_TEM-1. Plasmid IncF_repB was prevalent (65.9%, 95%CI = 50.1 - 79.5) among qnr determinants. Localisation of qnr determinants in IncF_repB and transferability of plasmids was further confirmed.

CONCLUSIONS

The current study proved that qnr in E. coli isolated from food-producing animals and their food products could spread via plasmid IncF_repB upon selective pressure with quinolones or other antimicrobials. Therefore, to curb the emergence and spread of qnr-harbouring bacteria in the Philippines, prudent use of antimicrobials in animal production and stricter hygiene and food handling are recommended.

Antimicrobial Resistance Surveillance of Pigs and Chickens in the Lao People’s Democratic Republic, 2018–2021

The use of antimicrobials in the livestock sector has been identified as a driver for the emergence of antimicrobial resistance (AMR), and AMR has become a growing public health and economic threat in the Lao PDR. We conducted surveillance for AMR in five provinces of the Lao PDR, in order to determine the antimicrobial susceptibility of Escherichia coli and Salmonella spp. isolated from caecal samples from slaughtered pigs at slaughterhouses and from slaughtered chickens at markets during two different time periods: 2018/2019 and 2020/2021. Antimicrobial susceptibility was determined using a panel of 14 antimicrobials using the broth microdilution technique. E. coli and Salmonella from chickens (62% and 33%, respectively) and pigs (88% and 81%, respectively) exhibited resistance to ≥3 classes of antimicrobials. Of important public health concern was the detection of Salmonella resistant to cefotaxime/ceftazidime, ciprofloxacin, and colistin, deemed as critically important antimicrobials in human medicine. This study aimed to evaluate a national sampling strategy at slaughterhouses and wet markets, and to pilot the laboratory methodologies for bacterial recovery and AMR testing. Experiences from this study will inform capacity development for a national AMR surveillance program, and these early data could serve as reference points for monitoring the impact of the Lao PDR’s national action plan to contain AMR.

The emergence of CTX-M-55 in ESBL-producing Escherichia coli from vegetables sold in local markets of northern Thailand

Extended-spectrum β-lactamase (ESBL)-producing Escherichia coli are spreading worldwide and pose a public health issue. An assessment of their presence in the environment and in food chain products would clarify the pathway of this foodborne transmission. Here, we investigated the prevalence of ESBL-producing E. coli in fresh vegetables purchased from fresh markets in Chiang Rai, Thailand. Overall, 8.8% of the samples collected contained ESBL-producing E. coli, of which 81.3% were multidrug-resistant. All isolates carried the bla_CTX-M-55 gene, and 10 isolates contained the ISEcp1 gene. One E. coli strain carried bla_CTX-M-55 coexisting with bla_TEM-1. Thirteen different sequence types (ST48, ST101, ST155, ST165, ST398, ST414, ST457, ST515, ST542, ST1081, ST3045, ST7538 and ST10651) were identified. One strain belonged to ST101, which is one of the most prevalent STs among human isolates. Our study thus demonstrated the spread of CTX-M-55 on non-ST131 vegetable isolates that are not global pandemic strains and suggests that they may be a source of antibiotic resistance gene transfer from agricultural foods to humans. Further studies are needed to investigate the possibility that these ESBL producers could transfer resistance genes to commensal E. coli and cause severe disease.

Genetic characterization of ESBL/pAmpC-producing Escherichia coli isolated from forest, urban park and cereal culture soils

Little is known about the role of forestland and non-fertilized agriculture soils as reservoirs of extended-spectrum beta-lactamase (ESBL) and plasmid-borne AmpC (pAmpC)-producing Escherichia coli isolates. Thus, in the present study, 210 soil samples from various origins (forest of Oued Zen (Ain Drahem), non-agriculture soils from different park gardens in Tunis City, cereal culture soils and home gardens) were investigated to characterize cefotaxime-resistant E. coli isolates. A total of 22 ESBL/pAmpC-producing E. coli were collected, and all harbored variants of the blaCTX-M gene (15 blaCTX-M-1, 5 blaCTX-M-55 and 2 blaCTX-M-15). A total of seven and two isolates harbored also blaEBC and blaDHA-like genes, respectively. Resistances to tetracycline, sulfonamides and fluoroquinolones were encoded by tetA (n = 4)/tetB (n = 12), sul1 (n = 17)/sul2 (n = 19) and aac(6')-Ib-cr (n = 2)/qnrA (n = 1)/qnrS (n = 1) genes, respectively. A total of seven isolates were able to transfer by conjugation cefotaxime-resistance in association or not with other resistance markers. PFGE showed that ten and two isolates were clonally related (pulsotypes P1 and P2). The 10 P1 isolates had been collected from forestland, cereal culture soils and an urban park garden in Tunis City, arguing for a large spread of clonal strains. Our findings highlight the occurrence of ESBL/pAmpC-E. coli isolates in soils under limited anthropogenic activities and the predominance of CTX-M enzymes that are largely disseminated in E. coli from humans and animals in Tunisia.

Colistin resistance and plasmid-mediated mcr genes in Escherichia coli and Salmonella isolated from pigs, pig carcass and pork in Thailand, Lao PDR and Cambodia border provinces

BACKGROUND

Colistin and carbapenem-resistant bacteria have emerged and become a serious public health concern, but their epidemiological data is still limited.

OBJECTIVES

This study examined colistin and carbapenem resistance in Escherichia coli and Salmonella from pigs, pig carcasses, and pork in Thailand, Lao PDR, and Cambodia border provinces.

METHODS

The phenotypic and genotypic resistance to colistin and meropenem was determined in E. coli and Salmonella obtained from pigs, pig carcasses, and pork (n = 1,619). A conjugative experiment was performed in all isolates carrying the mcr gene (s) (n = 68). The plasmid replicon type was determined in the isolates carrying a conjugative plasmid with mcr by PCR-based replicon typing (n = 7). The genetic relatedness of mcr-positive Salmonella (n = 11) was investigated by multi-locus sequence typing.

RESULTS

Colistin resistance was more common in E. coli (8%) than Salmonella (1%). The highest resistance rate was found in E. coli (17.8%) and Salmonella (1.7%) from Cambodia. Colistin-resistance genes, mcr-1, mcr-3, and mcr-5, were identified, of which mcr-1 and mcr-3 were predominant in E. coli (5.8%) and Salmonella (1.7%), respectively. The mcr-5 gene was observed in E. coli from pork in Cambodia. Two colistin-susceptible pig isolates from Thailand carried both mcr-1 and mcr-3. Seven E. coli and Salmonella isolates contained mcr-1 or mcr-3 associated with the IncF and IncI plasmids. The mcr-positive Salmonella from Thailand and Cambodia were categorized into two clusters with 94%-97% similarity. None of these clusters was meropenem resistant.

CONCLUSIONS

Colistin-resistant E. coli and Salmonella were distributed in pigs, pig carcasses, and pork in the border areas. Undivided-One Health collaboration is needed to address the issue.

Antimicrobial Resistance Genes in ESBL-Producing Escherichia coli Isolates from Animals in Greece

The prevalence of multidrug resistant, extended spectrum β-lactamase (ESBL)-producing Enterobacteriaceae is increasing worldwide. The present study aimed to provide an overview of the multidrug resistance phenotype and genotype of ESBL-producing Escherichia coli (E. coli) isolates of livestock and wild bird origin in Greece. Nineteen phenotypically confirmed ESBL-producing E. coli strains isolated from fecal samples of cattle (n = 7), pigs (n = 11) and a Eurasian magpie that presented resistance to at least one class of non β-lactam antibiotics, were selected and genotypically characterized. A DNA-microarray based assay was used, which allows the detection of various genes associated with antimicrobial resistance. All isolates harbored blaCTX-M-1/15, while blaTEM was co-detected in 13 of them. The AmpC gene blaMIR was additionally detected in one strain. Resistance genes were also reported for aminoglycosides in all 19 isolates, for quinolones in 6, for sulfonamides in 17, for trimethoprim in 14, and for macrolides in 8. The intI1 and/or tnpISEcp1 genes, associated with mobile genetic elements, were identified in all but two isolates. This report describes the first detection of multidrug resistance genes among ESBL-producing E. coli strains retrieved from feces of cattle, pigs, and a wild bird in Greece, underlining their dissemination in diverse ecosystems and emphasizing the need for a One-Health approach when addressing the issue of antimicrobial resistance.