Fluoroquinolone resistance determinants in carbapenem-resistant Escherichia coli isolated from urine clinical samples in Thailand.

Background: Escherichia coli is the most common cause of urinary tract infections and has fluoroquinolone (FQ)-resistant strains, which are a worldwide concern. Objectives: To characterize FQ-resistant determinants among 103 carbapenem-resistant E. coli (CREc) urinary isolates using WGS. Methods: Antimicrobial susceptibility, biofilm formation, and short-read sequencing were applied to these isolates. Complete genome sequencing of five CREcs was conducted using short- and long-read platforms. Results: ST410 (50.49%) was the predominant ST, followed by ST405 (12.62%) and ST361 (11.65%). Clermont phylogroup C (54.37%) was the most frequent. The genes NDM-5 (74.76%) and CTX-M-15 (71.84%) were the most identified. Most CREcs were resistant to ciprofloxacin (97.09%) and levofloxacin (94.17%), whereas their resistance rate to nitrofurantoin was 33.98%. Frequently, the gene aac(6')-Ib (57.28%) was found and the coexistence of aac(6')-Ib and blaCTX-M-15 was the most widely predominant. All isolates carried the gyrA mutants of S83L and D87N. In 12.62% of the isolates, the coexistence was detected of gyrA, gyrB, parC, and parE mutations. Furthermore, the five urinary CREc-complete genomes revealed that blaNDM-5 or blaNDM-3 were located on two plasmid Inc types, comprising IncFI (60%, 3/5) and IncFI/IncQ (40%, 2/5). In addition, both plasmid types carried other resistance genes, such as blaOXA-1, blaCTX-M-15, blaTEM-1B, and aac(6')-Ib. Notably, the IncFI plasmid in one isolate carried three copies of the blaNDM-5 gene. Conclusions: This study showed FQ-resistant determinants in urinary CREc isolates that could be a warning sign to adopt efficient strategies or new control policies to prevent further spread and to help in monitoring this microorganism.

Flagella-related gene mutations in Vibrio cholerae during extended cultivation in nutrient-limited media impair cell motility and prolong culturability.

IMPORTANCE: Vibrio cholerae undergoes a transition to a viable but non-culturable (VNC) state when subjected to various environmental stresses. We showed here that flagellar motility was involved in the development of the VNC state of V. cholerae. In this study, motility-defective isolates with mutations in various flagella-related genes, but not motile isolates, were predominantly obtained under the stress of long-term batch culture. Other genomic regions were highly conserved, suggesting that the mutations were selective. During the stationary phase of long-term culture, V. cholerae isolates with mutations in the acetate kinase and flagella-related genes were predominant. This study suggests that genes involved in specific functions in V. cholerae undergo mutations under certain environmental conditions.

Temporal shifts in the predominant carbapenemase gene types among carbapenemase-producing Klebsiella pneumoniae isolated in Bangkok, Thailand, during 2013-2016.

Introduction. Carbapenemase-producing Enterobacteriaceae (CPE) have emerged as a global threat to public health and clinical practice.Hypothesis/Gap Statement. In Thailand, reports describing CPEs carrying bla NDM and bla OXA-48-like genes have been increasing recently; however, data on detailed plasmid analysis and temporal shift of sequence type and carbapenemase type are limited.Aim. In this study, we analysed whole-genome sequencing (WGS) data of clinically isolated carbapenemase-producing Klebsiella pneumoniae (CPKP) to reveal the molecular epidemiology of CPKP in a tertiary-care hospital in Bangkok, Thailand.Methodology. Seventy-seven non-duplicated CPKP isolates collected during 2013-2016 were examined for their drug-resistance genes, sequence types and phylogenetic relationships.Results. All the tested isolates possessed carbapenemase gene(s), and the major type of carbapenemase gene in 2014-2015 was bla NDM-1, whereas isolates in 2016 harboured more bla OXA-232 than bla NDM-1. Other carbapenemase gene variants, such as bla NDM-4, bla NDM-5, bla OXA-48, bla OXA-181 and bla IMP-14 were detected in some CPKP isolates. Furthermore, this study revealed that CPKP co-harbouring two genes, bla NDM-1 and bla OXA-232 or bla OXA-181, emerged during this period. Notably, such isolates co-carrying the two carbapenemase genes emerged in three different sequence types, even in a single hospital, and then spread clonally. The WGS of CPKP revealed a temporal shift of the predominant carbapenemase genes from bla NDM-1 to bla OXA-232 along with a variation in other carbapenemase gene types within a span of 4 years.Conclusion. Our findings suggest that a substantial change in CPE types occurred in Thailand and potentially in Southeast Asian countries.

Carbapenem triggers dissemination of chromosomally integrated carbapenemase genes via conjugative plasmids in Escherichia coli.

Epidemiological surveys have shown that carbapenem resistance is mainly transmitted across species by carbapenemase genes located on conjugative plasmids. As chromosomal integration of carbapenemase genes has rarely been identified, only a few studies have investigated their advantages to the carbapenem-resistant bacterial community. Here, we confirmed the increased stability of blaIMP-6 on a chromosome-integrated plasmid in an Escherichia coli isolate compared with that on original plasmids in the absence of antibiotic pressure. Although plasmids carrying carbapenemase genes are supposedly lost in successive generations, we found that the complete plasmid backbone was retained in bacterial cells even after the occasional loss of their antibiotic-resistance cassettes. This backbone structure has been observed worldwide to carry various antimicrobial resistance genes. Although the chromosomally integrated plasmid carrying blaIMP-6 could not be transmitted by conjugation, we found that meropenem treatment for 1 wk allowed the plasmid to be released from the chromosome and spread among E. coli strains that were susceptible to meropenem. The copy number of blaIMP-6 on the plasmid was amplified eight times, resulting in enhanced resistance. Although the carbapenemase producers that carry chromosomal carbapenemase genes comprised of small subpopulations, they functioned as stable, long-term reservoirs of carbapenem resistance that could be disseminated via plasmids with amplified resistance upon meropenem stimulation. Although plasmids occasionally lose their resistance cassettes as a scaffold for the acquisition of another resistance gene, chromosomal integration may contribute to the effective sharing of carbapenem resistance within a population, complicating the development of a strategy to avoid the dissemination of antimicrobial resistance. IMPORTANCE Although carbapenem antibiotics are the last resort for combating multidrug-resistant organisms, global dissemination of carbapenem-resistant Enterobacteriaceae (CRE) threatens public health. Carbapenemases, which are enzymes responsible for carbapenem resistance, are mainly encoded by genes on plasmids that can be transmitted across bacterial species. Owing to the rarity of chromosomally encoded carbapenemase genes, studies investigating their properties in bacterial communities are lacking. In our study, we revealed the stability of carbapenemase genes on chromosomes compared with those on plasmids, which can be lost through the loss of antimicrobial resistance cassettes despite robust retention of plasmid backbones. Following exposure to meropenem, the carbapenemase gene integrated into the chromosome was released as a plasmid, restarting the dissemination of enhanced carbapenem resistance through amplified copy numbers of carbapenemase genes. Chromosomally encoded carbapenemase genes may function as a reservoir of resistance genes within the bacterial community and challenge infection control against CRE dissemination.

Molecular Characterization of Mutations in Isoniazid- and Rifampicin-Resistant Mycobacterium tuberculosis Isolated in Thailand.

The control of drug-resistant tuberculosis (TB) is a major challenge. The frequency and mutation characteristics indicate the efficiency of molecular tests for the rapid detection of TB drug resistance. This study examined the existence of katG and inhA mutations for isoniazid (INH) resistance and rpoB mutations for rifampicin (RFP) resistance. In total, 178 drug-resistant Mycobacterium tuberculosis (MTB) isolates were analyzed. Mutations in katG encoding and inhA regulatory regions were detected in 136/168 (81.0%) and 29/168 (17.3%), respectively, with the most prominent mutation of Ser315Thr substitution in katG in 126/168 (75.0%), and -15 C to T substitution in the regulatory region of the inhA (26/168; 15.5%). Two distinct katG mutations (Tyr337Cys, 1003InsG) were identified. Of 125 RFP-resistant isolates, 118 (94.4%) carried mutations affecting the 81-bp RFP resistance-determining region, with the most commonly affected codons 450, 445, and 435 identified in 74 (59.2%), 26 (20.8%), and 12 (9.6%) isolates, respectively. Genetic mutations were highly associated with phenotypic INH and RFP resistance, and the majority shared similarities with those reported in previous studies in Thailand and other Asian countries. These data are useful for guiding the use and improvement of molecular tests for TB drug resistance.

A Nationwide Plasmidome Surveillance in Thailand Reveals a Limited Variety of New Delhi Metallo-ß-Lactamase-Producing Carbapenem-Resistant Enterobacteriaceae Clones and Spreading Plasmids.

Despite frequent identification of plasmids carrying carbapenemase genes, the transfer of plasmids carrying carbapenemase genes is not well recognized in clinical settings because of technical limitations. To investigate the detailed mechanisms of the spread of carbapenem-resistant Enterobacteriaceae (CRE), we performed multifaceted genomic surveillance of CRE isolates in Thailand and analyzed their plasmidome. We analyzed 371 Enterobacteriaceae isolates carrying blaNDM-1 and 114 Enterobacteriaceae isolates carrying blaNDM-5 obtained from clinical samples of 473 patients in 11 representative hospitals located in six provinces in Thailand between 2012 and 2017. The complete structures of plasmids carrying blaNDM and chromosomal phylogeny were determined by combining Southern blotting hybridization analysis and our previously performed whole-genome short-read sequencing data. Dissemination of the blaNDM-5 gene among the Enterobacteriaceae isolates in Thailand was mainly owing to the nationwide clonal spread of Escherichia coli ST410 and regional clonal spreads of Escherichia coli ST361 and ST405. Analysis of blaNDM-1-carrying isolates revealed nationwide dissemination of two specific plasmids and nationwide clonal dissemination of Klebsiella pneumoniae ST16 accompanied with regional disseminations of three distinctive K. pneumoniae clones (ST231, ST14, and ST147) with different plasmids. Dissemination of CRE carrying blaNDM in Thailand is mainly based on nationwide clonal expansions of E. coli ST410 carrying blaNDM-5 and K. pneumoniae ST16 carrying blaNDM-1, nationwide dissemination of two distinctive plasmids carrying blaNDM-1, and accumulation of clonal expansions in regional areas. Although the overuse of antibiotics can promote CRE dissemination, the limited variety of transmitters highlights the importance of preventing horizontal dissemination among patients.

Clonal dissemination of carbapenem-resistant Klebsiella pneumoniae ST16 co-producing NDM-1 and OXA-232 in Thailand.

Background: Klebsiella pneumoniae ST258 and ST11 carrying bla KPC are among the most widespread carbapenem-resistant K. pneumoniae strains worldwide. Our carbapenem-resistant Enterobacteriaceae surveillance in Thailand revealed a nationwide dissemination of K. pneumoniae ST16 isolates carrying bla NDM-1 and bla OXA-232. Objectives: To analyse the genomic details of this nationwide dissemination by focusing on plasmids and virulence factors. Methods: Using WGS data of 119 K. pneumoniae ST16 isolates carrying bla NDM-1 obtained in our previous surveillance study, clonality of chromosomes and plasmids of the isolates with carriage of virulence factors was evaluated. Results: Of the 119 isolates, 111 carried plasmid pKP151_NDM1, and all 104 isolates harbouring bla OXA-232 carried plasmid pKP151_OXA232. These 104 K. pneumoniae ST16 isolates showing chromosomal clonality possessed both pKP151_NDM1 and pKP151_OXA232, demonstrating clonal dissemination of K. pneumoniae ST16 with these plasmids. The isolates had essentially similar virulence factors as those of K. pneumoniae ST16 clones carrying bla KPC, which were recently reported as highly invasive clones in Brazil. Conclusions: The potential global dissemination of these invasive clones with resistance to several antibiotics highlights the importance of appropriate monitoring and strict standard precautions.

Role of Chromosome- and/or Plasmid-Located blaNDM on the Carbapenem Resistance and the Gene Stability in Escherichia coli.

The spread of New Delhi metallo-ß-lactamase (NDM)-producing Enterobacterales represents a public health risk. The horizontal transfer of plasmids encoding the NDM gene, blaNDM, usually mediates its spread to other bacteria within the family. In contrast, Enterobacterales with a chromosome-located blaNDM is rarely reported. The phenotypic differences between chromosome- and plasmid-located carbapenemase genes are poorly understood. To determine the significance in terms of the location of drug resistance genes, we examined carbapenemase activity and stability of chromosome- and plasmid-located blaNDM. Escherichia coli M719 possessing both chromosomes- and plasmid-located blaNDM genes was used as a wild-type strain (WT) for the construction of mutants, ΔpblaNDM and ΔcblaNDM, wherein chromosome- or plasmid-located blaNDM, was knocked out, respectively. The mutant ΔpblaNDM showed lower hydrolyzing activity against imipenem and gene expression than the WT or ΔcblaNDM mutant. The MICs of both mutant strains were still above the breakpoint of imipenem and meropenem. Moreover, the chromosome-located blaNDM gene was stable for at least 30 days in the absence of antimicrobial pressure, whereas the ΔcblaNDM mutant lost blaNDM to 87% at 30 days compared to that of the initial inoculum. Organisms harboring the plasmid-located carbapenemase genes were found to provide a higher level of carbapenem resistance than those with chromosome-located genes. However, the latter organisms with chromosomal carbapenemase genes exhibited more stable carbapenem resistance than did the former ones. In summary, chromosomally located carbapenemase genes require further monitoring and more attention should be paid to them. IMPORTANCE Carbapenem-resistant Enterobacterales (CRE) carrying blaNDM have spread worldwide since they were first reported in 2009. Many studies using whole-genome sequencing have identified the genetic structures, plasmid scaffolds of blaNDM, and mechanisms of spread via horizontal transfer. Chromosome-located blaNDM and integration mechanisms from plasmids have rarely been reported, and their significance is not fully understood. Here, we showed that the chromosome-located blaNDM was associated with lower levels of carbapenem resistance and carbapenemase activity than the plasmid-located blaNDM. However, it conferred carbapenem resistance above the breakpoints and the loss of chromosome-located blaNDM was not observed in the absence of antibiotic pressure. This study suggests that CRE strains carrying chromosome-located blaNDM may persist in clinical and environmental settings for a long period even without antibiotic pressure and need to be monitored along with plasmid-located blaNDM.

Population analysis profiling: is it still the gold standard for the determination of heteroresistance in carbapenemase-producing Enterobacteriaceae?

Heteroresistance is the phenomenon wherein subpopulations of presumed isogenic bacteria show varied antibiotic susceptibilities, and the current gold standard for the determination of heteroresistance is population analysis profiling (PAP). However, when conducting PAP to confirm carbapenem heteroresistance in Enterobacteriaceae, the authors found some isolates that did not seem to be heteroresistant, despite meeting PAP criteria. This article elaborates on the validity of PAP for the determination of heteroresistance, especially among carbapenemase-producing Enterobacteriaceae (CPE). Bacterial cells that were originally non-viable on selective agar supplemented with a high concentration of meropenem were found to be occasionally viable, likely due to the hydrolysis of carbapenems by carbapenemases produced by dying cells, mimicking the emergence of subpopulations with enhanced resistance. As such, PAP for CPE is highly affected by carbapenemases produced by dying populations, and may not detect heterogeneity in carbapenem resistance appropriately among seemingly isogenic clones.

Corrigendum to: Phylogenetic Analysis Revealed the Dissemination of Closely Related Epidemic Vibrio cholerae O1 Isolates in Laos, Thailand, and Vietnam.

[This corrects the article DOI: 10.1093/ofid/ofaa492.].

Klebsiella pneumoniae Complex Harboring mcr-1, mcr-7, and mcr-8 Isolates from Slaughtered Pigs in Thailand.

Dissemination of the mobile colistin resistance gene mcr in Enterobacterales among humans, animals, and the environment is a public health issue. We characterized mcr genes in the Klebsiella pneumoniae complex (KpnC) isolated from slaughtered pigs in Thailand. The 280 KpnCs consisted of K. pneumoniae (85%), Klebsiella quasipneumoniae (8.21%), and Klebsiella variicola (6.79%). mcr genes were detected in 6.79% (19/280) of KpnC isolates, consisting of mcr-8 (n = 9; 3.21%), mcr-7 (n = 7; 2.50%), mcr-7 + mcr-8 (n = 2; 0.71%), and mcr-1 + mcr-7 (n = 1; 0.36%). K. pneumoniae predominantly carried the mcr-7 and mcr-8 genes, while K. variicola and K. quasipneumoniae harbored mcr-7 and mcr-8, respectively. Six of the nineteen mcr-harboring KpnC isolates exhibited colistin resistance, and five had mcr-1 or mcr-8 transferable to an Escherichia coli recipient. Antimicrobial susceptibility analysis revealed that all mcr-carrying KpnC isolates were susceptible to carbapenems, cefotaxime, cefepime, amoxicillin/clavulanic acid, piperacillin/tazobactam, amikacin, and fosfomycin, and had high resistance to azithromycin. Multilocus sequence analysis demonstrated that the mcr-harboring KpnC isolates were genetically diverse. A 'One-Health' approach is useful to combat antimicrobial-resistant bacteria through coordinating the human, animal, and environmental sectors. Hence, continuous monitoring and surveillance of mcr-carrying KpnCs throughout the pork supply chain is crucial for ensuring public health.

Transmission dynamics of a linear vanA-plasmid during a nosocomial multiclonal outbreak of vancomycin-resistant enterococci in a non-endemic area, Japan.

The spread of vancomycin-resistant enterococci (VRE) is a major threat in nosocomial settings. A large-scale multiclonal VRE outbreak has rarely been reported in Japan due to low VRE prevalence. We evaluated the transmission of vancomycin resistance in a multiclonal VRE outbreak, conducted biological and genomic analyses of VRE isolates, and assessed the implemented infection control measures. In total, 149 patients harboring VanA-type VRE were identified from April 2017 to October 2019, with 153 vancomycin-resistant Enterococcus faecium isolated being grouped into 31 pulsotypes using pulsed-field gel electrophoresis, wherein six sequence types belonged to clonal complex 17. Epidemic clones varied throughout the outbreak; however, they all carried vanA-plasmids (pIHVA). pIHVA is a linear plasmid, carrying a unique structural Tn1546 containing vanA; it moves between different Enterococcus spp. by genetic rearrangements. VRE infection incidence among patients in the "hot spot" ward correlated with the local VRE colonization prevalence. Local prevalence also correlated with vancomycin usage in the ward. Transmission of a novel transferrable vanA-plasmid among Enterococcus spp. resulted in genomic diversity in VRE in a non-endemic setting. The prevalence of VRE colonization and vancomycin usage at the ward level may serve as VRE cross-transmission indicators in non-intensive care units for outbreak control.

Fluoroquinolone resistance in non-typhoidal Salmonella enterica isolated from slaughtered pigs in Thailand.

Introduction. The emergence and spread of non-typhoidal Salmonella enterica (NTS) serovars resistant to fluoroquinolones and third- and higher-generation cephalosporins is a matter of great concern. Antimicrobial-resistant NTS is increasingly being discovered in humans, animals, food animals, food products, and agricultural environments. Pigs are considered a major reservoir of antimicrobial-resistant Salmonella spp.Hypothesis/Gap Statement. Fluoroquinolone-resistant Salmonella spp. warrant further surveillance and characterization for a better understanding of the bacteria isolated from animals.Aim. NTS isolated from pork from slaughterhouses across Thailand were characterized in terms of their serovars; resistance to fluoroquinolones, third-generation cephalosporins, and carbapenems; and antimicrobial resistance genes.Methodology. A total of 387 NTS isolates, collected from slaughtered pigs in ten provinces across Thailand between 2014 and 2015, were characterized based on their serovars, antimicrobial resistance genes, and susceptibility to fluoroquinolones, third-generation cephalosporins, and carbapenems.Results. Among all NTS isolates, S. enterica serovar Rissen was predominant. Antimicrobial resistance was exhibited in 93/387 isolates (24 %). Although 24 (6.2 %) isolates were susceptible to all the tested antimicrobials, they were found to possess ß-lactamase genes, such as bla TEM, bla SHV, or bla CTX-M. Mobilized colistin-resistant genes (mcr) and resistance to colistin were not observed in any tested isolate. Carbapenem resistance was detected in ten isolates (10.7 %); however, bla KPC, bla NDM, bla OXA-48-like, and bla IMP were not present. Among the 93 antimicrobial-resistant isolates, 87.1 % showed fluoroquinolone resistance with the quinolone resistance gene (qnrS) combined with topoisomerase genes parC (T57S) or gyrA (S83E/Y and D124E/G) substitutions, or topoisomerase gene substitutions alone.Conclusion. We found high fluoroquinolone resistance rates among the NTS isolates from pigs from slaughterhouses. The fluoroquinolone resistance mechanism in NTS was associated with the combination of qnrS and substitutions in gyrA, parC, or both. To prevent the transmission of antimicrobial-resistant NTS between animals and humans, continuous monitoring, surveillance, and regulation of Salmonella in the pork supply chain are pivotal.

Enhanced Carbapenem Resistance through Multimerization of Plasmids Carrying Carbapenemase Genes.

The worldwide dissemination of carbapenem-resistant Enterobacteriaceae (CRE) poses a critical human health issue by limiting the range of antibiotics that are usable in the treatment of common bacterial infections. Along with CRE, carbapenem heteroresistance has disseminated worldwide, which is described as different levels of carbapenem resistance within a seemingly isogenic bacterial population. Unstable carbapenem resistance will likely lead to unexpected treatment failure due to the enhanced resistance after initiation of treatment, contradicting antimicrobial susceptibility test results. Porin mutation and tandem amplification of the carbapenemase gene have been reported as mechanisms underlying enhanced carbapenem resistance. In this study, we identified multimerization of plasmids carrying carbapenemase genes, by using Southern blotting, whole-genome sequencing, and quantitative PCR (qPCR) analysis for the CRE isolates obtained in our previous surveillance in Osaka, Japan. Plasmids harboring a carbapenemase gene were multimerized by recA, likely through recombination at two consecutive sets of transposase genes of the IS91 family, thereby producing various plasmids of discrete sizes in a single bacterial cell of an Escherichia coli isolate. This multimerization resulted in increased copy numbers of carbapenemase genes, leading to enhanced gene transcription as well as carbapenem resistance. Prior exposure to meropenem further increased the copy number of carbapenemase genes, readily resulting in enhancement of carbapenem resistance. This mechanism may lead to clinical treatment failure by sifting antimicrobial resistance after the treatment initiation. IMPORTANCE We demonstrated the multimerization of plasmids harboring carbapenemase genes, and multimeric plasmids of various discrete sizes existed in a host bacterial cell of Escherichia coli. Plasmid multimerization along with increased copy numbers of carbapenemase genes resulted in enhanced carbapenemase resistance, which was readily accelerated by an overnight preexposure to meropenem. This mechanism may lead to treatment failure in clinical settings after the initiation of antimicrobial therapy.

Characterization of bla NDM-5-harbouring Klebsiella pneumoniae sequence type 11 international high-risk clones isolated from clinical samples in Yangon General Hospital, a tertiary-care hospital in Myanmar.

Fifteen Klebsiella pneumoniae isolates harbouring bla NDM genes were identified from blood and sputum specimens of patients at a tertiary-care facility (Yangon General Hospital, Yangon, Myanmar) in 2018. Two of the isolates belonged to sequence type (ST) 11, an international high-risk clone. Whole-genome sequencing and phylogenetic analyses revealed that these two isolates were clustered together with other ST11 isolates originating from other countries. The isolates harboured the bla NDM-5 gene on an IncFII-type plasmid that is prevalent among carbapenemase-producing Enterobacteriaceae in Yangon but has rarely been found in other ST11 isolates. Our data suggests the regional presence of the ST11 international high-risk clone and its acquisition of an endemic bla NDM-5-carrying plasmid.

Community spread and acquisition of clinically relevant Escherichia coli harbouring blaNDM among healthy Japanese residents of Yangon, Myanmar.

BACKGROUND: Carbapenemase-producing Enterobacterales (CPE) are spreading in hospitals, environment and retail foods in Yangon, Myanmar. OBJECTIVES: To investigate whether CPE colonize healthy individuals living in Yangon and whether clinical-related strains are spreading in the community. METHODS: CPE was isolated from faecal samples obtained from healthy Japanese residents of Yangon with no history of hospitalization. Isolates were subjected to WGS using short- and long-read sequencers and compared with those previously isolated in Yangon. RESULTS: Six Escherichia coli strains harbouring blaNDM-1 or blaNDM-5 belonging to five different STs-ST10, ST38, ST48, ST410 and ST8453-were isolated from 69 volunteers. The ST38 isolates were related to those previously isolated from retail food in Yangon. The ST410 and ST8453 isolates were highly related to previous Yangon isolates including those of clinical and food origins. CONCLUSIONS: The analysis suggested the acquisition of blaNDM-positive E. coli, which are disseminating in a clinical setting and through retail foods, by healthy residents in Yangon.

Genomic Characterization of Clinical Extensively Drug-Resistant Acinetobacter pittii Isolates.

Carbapenem-resistant Acinetobacter pittii (CRAP) is a causative agent of nosocomial infections. This study aimed to characterize clinical isolates of CRAP from a tertiary hospital in Northeast Thailand. Six isolates were confirmed as extensively drug-resistant Acinetobacter pittii (XDRAP). The blaNDM-1 gene was detected in three isolates, whereas blaIMP-14 and blaIMP-1 were detected in the others. Multilocus sequence typing with the Pasteur scheme revealed ST220 in two isolates, ST744 in two isolates, and ST63 and ST396 for the remaining two isolates, respectively. Genomic characterization revealed that six XDRAP genes contained antimicrobial resistance genes: ST63 (A436) and ST396 (A1) contained 10 antimicrobial resistance genes, ST220 (A984 and A864) and ST744 (A56 and A273) contained 9 and 8 antimicrobial resistance genes, respectively. The single nucleotide polymorphism (SNP) phylogenetic tree revealed that the isolates A984 and A864 were closely related to A. pittii YB-45 (ST220) from China, while A436 was related to A. pittii WCHAP100020, also from China. A273 and A56 isolates (ST744) were clustered together; these isolates were closely related to strains 2014S07-126, AP43, and WCHAP005069, which were isolated from Taiwan and China. Strict implementation of infection control based upon the framework of epidemiological analyses is essential to prevent outbreaks and contain the spread of the pathogen. Continued surveillance and close monitoring with molecular epidemiological tools are needed.

Distribution and Molecular Characterization of Escherichia coli Harboring mcr Genes Isolated from Slaughtered Pigs in Thailand.

The resistance of Enterobacteriaceae to colistin mediated by plasmid-borne mobile mcr genes is an emerging public health concern. This study aimed to explore the distribution and characteristics of Escherichia coli isolates harboring mcr genes from slaughtered pigs in Thailand from 2014 to 2015. A total of 779 E. coli isolates were assessed, of which 61 (7.8%) were found to carry mcr genes, including mcr-1, mcr-3, mcr-6, mcr-7, mcr-8, and mcr-9, together with co-occurrences of mcr-1+mcr-3, mcr-1+mcr-9, and mcr-3+mcr-6+mcr-7. In these mcr-harboring E. coli isolates, mcr-1 (40.9%) and mcr-9 (32.8%) were predominant. Colistin resistance was mainly mediated by the mcr-1 gene, whereas intermediate resistance was noted in isolates that harbored mcr-9, mcr-6, mcr-7, and mcr-8 genes. Most E. coli isolates harboring mcr genes were susceptible to third-generation cephalosporins and all of these isolates were susceptible to carbapenems. Clermont phylotyping demonstrated that mcr-harboring isolates mainly belonged to phylogroup A (44.3%), followed by phylogroups B1 (34.4%), D (14.8%), and B2 (6.6%). Multilocus sequence typing revealed that 25 sequence types (STs) were assigned to 45 mcr-harboring E. coli isolates, whereas the remaining 16 isolates were novel STs. The mcr-1 and mcr-9 genes were mostly predominant in ST101 and ST8900, respectively. This study provides a comprehensive insight into the prevalence and diversity of mcr-harboring E. coli isolates obtained from slaughtered pigs across Thailand. Strengthening of surveillance systems by the government for controlling and preventing mcr dissemination from animals to humans or vice versa is urgently needed. No clinical trial registration number.