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Complete Genetic Analysis of Plasmids Carried by Two Nonclonal bla_NDM-5- and mcr-1-Bearing Escherichia coli Strains: Insight into Plasmid Transmission among Foodborne Bacteria.

ABSTRACT: Our objective was to characterize the genetic features of plasmids harbored by two genetically related, MCR-1 and NDM-5-producing Escherichia coli strains recovered from a chicken meat sample. The genetic profiles of all plasmids harbored by the two test strains, namely, 1106 and 1107, were determined by whole-genome sequencing, S1-pulsed-field gel electrophoresis (PFGE), Southern hybridization, and bioinformatics analysis. The transferability of plasmids harbored by the two strains was assessed by filter mating assay. Strains 1106 and 1107 were resistant to almost all the antibiotics, including colistin and fosfomycin, but remained susceptible to amikacin and tigecycline. The plasmids of p1107-NDM-5 and p1106-NDM-5 both contain a class I integron which lacks the ISAba125 element. The backbone of p1106-IncFII exhibited a high degree of similarity with that of p1106-NDM-5 and p1107-NDM-5, implying that events of plasmid fusion and resolution were involved in the formation of the two plasmids. The plasmids p1106-IncHI2MCR and p1107-IncHI2MCR belong to an IncHI2 replicon type, with three copies of ISApl1 being observed in p1106-IncHI2MCR, implying that the mcr-1 gene was transferable among bacteria that reside in the same food matrix. In this study, p1106-IncFIB, p1107-99K, p1107-111K, and p1107-118K were all found to be phage-like plasmids, with p1106-IncFIB and p1107-118K containing several virulence genes, including iroBCDEN, iucABCD, sitABCD, hlyF, and iss. Surprisingly, resistance genes such as aph(3')-Ia, sul3, and aac(3')-IId could also be found in p1107-118K, but resistance genes were not detected in other phage-like plasmids. In conclusion, enhanced surveillance is required to monitor and control the dissemination of various resistance determinants among foodborne pathogens. IMPORTANCE Carbapenem and colistin are last-resort antibiotics used to treat serious clinical infections caused by multidrug-resistant (MDR) bacterial pathogens. Plasmids encoding resistance to carbapenems and colistin have been reported in clinical pathogens in recent years, and yet few studies reported cocarriage of mcr and bla_NDM genes in Escherichia coli strains of food origin. How plasmids encoding these two important resistance determinants are being evolved and transmitted in bacterial pathogens is not well understood. In this study, we investigated the genetic features of plasmids harbored by two nonclonal, mcr-1- and bla_NDM-5-bearing E. coli strains (1106 and 1107) recovered from a fresh chicken meat sample to understand and provide evidence of the level and dynamics of MDR plasmid transmission. Our data confirmed that active plasmid fusion and resolution events were involved in the formation of plasmids that harbor multiple resistance genes, which provide insights into the further control of plasmid evolution in bacterial pathogens.

SUBMITTER: Liu X

PROVIDER: S-EPMC8557939 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:In clinical practice, carbapenems and tigecycline are considered significant options for treating infections caused by multidrug-resistant Klebsiella spp. The continual evolution of resistance mechanisms to carbapenems and tigecycline is shattering the present condition. Meanwhile, convergence of the two resistance mechanisms in a single strain has been reported repeatedly, posing a significant threat to public health and safety. In this study, two carbapenem- and tigecycline-resistant Klebsiella species were obtained from patients and investigated using antimicrobial susceptibility testing, conjugation assay, whole-genome sequencing, and bioinformatics analysis. In Klebsiella variicola FK2020ZBJ35, an untransferable multidrug IncFIB(Mar)/IncHI1B-like plasmid carrying tmexCD2-toprJ2, blaIMP-4, and blaNDM-1 was discovered, as was a similar plasmid carrying tmexCD1-toprJ1 and blaIMP-4 in Klebsiella quasipneumoniae 2019SCSN059. Genetic context analysis found that two distinct tmexCD-toprJ variants were detected in comparable mobile units with genetic array int-int-hp-hp-tnfxB-tmexCD-toprJ and integrated into separate genetic locations. blaIMP-4 and blaNDM-1 were carried by an integron In1377 and a truncated Tn3000, respectively. These findings revealed that the carbapenem and tigecycline resistance genes carried by the two strains were located on mobile elements and might potentially transmit horizontally to additional strains. Furthermore, our findings showed that IncFIB(Mar)/IncHI1B-like plasmids represent a significant reservoir of essential resistance genes that warrants continued monitoring. IMPORTANCE Tigecycline is an essential antibiotic that is used to treat infections caused by carbapenem-resistant Klebsiella pneumoniae (CRKP). The emergence of high-level tigecycline-resistant CRKP poses a serious hazard to human health. This work screened two tigecycline-resistant CRKP strains from clinical patients and found a type of plasmid that encoded carbapenemase and TmexCD-ToprJ in Klebsiella. Importantly, one plasmid cocarried tmexCD-toprJ, blaNDM-1, and blaIMP-4, hinting that this plasmid could be a critical vector for superbug development. Furthermore, we discovered that the carbapenem and tigecycline resistance genes are located in mobile units by genetic structure analysis. Our research tracks the formation of clinically super-resistant Gram-negative bacteria.

Project description:The global spread of colistin or carbapenem-resistant Enterobacteriaceae (CRE) has been a pressing threat to public health. Members of Enterobacteriaceae, especially Proteus mirabilis and Escherichia coli, have been prevalent foodborne pathogens and such pathogens from fresh vegetables have triggered foodborne illness in China. However, reports about CRE, especially P. mirabilis from fresh vegetables, are still lacking. In this study, we identified five blaNDM-positive P. mirabilis and five blaNDM-positive generic E. coli concurrently from five fresh vegetables in two markets from China, and four of the five E. coli also carried mcr-1. The 10 isolates were characterized with methods including antimicrobial susceptibility testing, conjugation, whole-genome sequencing and phylogenetic analysis. All 10 isolates were multidrug-resistant (MDR). blaNDM-5 in five E. coli isolates and one P. mirabilis carrying blaNDM-5 was located on similarly transferable IncX3 plasmids, while transferably untypable plasmids were the carriers of blaNDM-1 in four P. mirabilis isolates from different types of vegetables/markets. mcr-1 in the four blaNDM-5-positive E. coli was located on similarly non-conjugative IncHI2 MDR plasmids lacking transfer region. Notably, ISCR1 complex class 1 integron capable of capturing blaNDM-1 was found on all untypable plasmids from P. mirabilis, and five copies of ISCR1 complex class 1 integron containing blaNDM-1 even occurred in one P. mirabilis, which showed high-level carbapenem resistance. Plasmid and phylogenetic analysis revealed that the blaNDM-positive P. mirabilis and E. coli from fresh vegetables might be derived from animals and transmitted to humans via the food chain. The concurrence of blaNDM-positive P. mirabilis and E. coli carrying both mcr-1 and blaNDM in different types of fresh vegetables eaten raw is alarming and threatens food safety. Sustained surveillance of these foodborne pathogens among fresh vegetables is urgent to ensure the health of food consumers. We report for the first time the concurrence of blaNDM-positive P. mirabilis and mcr-1-bearing E. coli carrying blaNDM from the same fresh vegetables.

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Complete Genetic Analysis of Plasmids Carried by Two Nonclonal bla_NDM-5- and mcr-1-Bearing Escherichia coli Strains: Insight into Plasmid Transmission among Foodborne Bacteria.

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Complete Genetic Analysis of Plasmids Carried by Two Nonclonal blaNDM-5- and mcr-1-Bearing Escherichia coli Strains: Insight into Plasmid Transmission among Foodborne Bacteria.

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OmicsDI is part of the ELIXIR infrastructure

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Complete Genetic Analysis of Plasmids Carried by Two Nonclonal bla_NDM-5- and mcr-1-Bearing Escherichia coli Strains: Insight into Plasmid Transmission among Foodborne Bacteria.