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149200.9917Characterization of the tet(M)-bearing transposon Tn7125 of Escherichia coli strain A13 isolated from an intensive pig farm located in Henan province, China. BACKGROUND: Transposons carrying tet(M) in Gram-positive bacteria have been reported extensively, while there is a paucity of data on the transmission characteristics of tet(M) in Gram-negative bacteria. Therefore, the aim of this study was to investigate the genetic characteristics of the tet(M)-bearing transposon Tn7125, and to clarify the transmission mechanism of the plasmids pTA13-1 and pTA13-3 in Escherichia coli strain A13. METHODS: Plasmids from strain A13 and a corresponding transconjugant were determined by whole genome sequencing and analyzed using bioinformatics tools. The plasmids pTA13-1 and pTA13-3 of the transconjugant TA13 were characterized by S1-pulse-field gel electrophoresis, Southern hybridization, stability experiments, and direct competition assays. RESULTS: The conjugated IncF2:A6:B20 plasmid pTA13-1 co-transferred with the 41-kb plasmid pTA13-3, which carried no resistance genes; plasmid pTA13-2, which harbored the replication initiator PO111; and the IncX4 plasmid pTA13-4, which harbored the antibiotic resistance gene mcr-1. The novel IS26-bracked composite transposon Tn7125 was located on plasmid pTA13-1, which mainly consists of three resistance modules: IS26-ctp-lp-tet(M)-hp-IS406tnp, qac-aadA1-cmlA1-aadA2-DUF1010-dfrA12, and ∆ISVSa3-VirD-floR-LysR-ISVSa3. The plasmid pTA13-1 was highly stable in E. coli strain J53 with no fitness cost to the host or disadvantage in growth competition. CONCLUSION: Evolution of co-integrated transposons, such as Tn7125, may convey antibiotic resistance to a wide spectrum of hosts via the plasmids pTA13-1 and pTA13-3, which acts as an adaptable and mobile multidrug resistance reservoir to accelerate dissemination of other genes by co-selection, thereby posing a potentially serious barrier to clinical treatment regimens.202540639501
83410.9914Molecular diversity of class 2 integrons in antibiotic-resistant gram-negative bacteria found in wastewater environments in China. The molecular architecture of class 2 integrons among gram-negative bacteria from wastewater environments was investigated in Jinan, China. Out of the 391 antibiotic-resistant bacteria found, 38 isolates harboring class 2 integrons encoding potentially transferrable genes that could confer antibiotic resistance were found. These isolates were classified into 19 REP-PCR types. These strains were identified using 16S rRNA gene sequencing and found to be as follows: Proteus mirabilis (16), Escherichia coli (7), Providencia spp. (7), Proteus spp. (2), P. vulgaris (3), Shigella sp. (1), Citrobacter freundii (1), and Acinetobacter sp. (1). Their class 2 integron cassette arrays were amplified and then either analyzed using PCR-RFLP or sequenced. The typical array dfrA1-sat2-aadA1 was detected in 27 isolates. Six atypical arrays were observed, including three kinds of novel arrangements (linF2(∆attC1)-dfrA1(∆attC2)-aadA1-orf441 or linF2(∆attC1)-dfrA1(∆attC2)-aadA1, dfrA1-catB2-sat2-aadA1, and estX(Vr)-sat2-aadA1) and a hybrid with the 3'CS of class 1 integrons (dfrA1-sat2-aadA1-qacH), and dfrA1-sat1. Twenty-four isolates were also found to carry class 1 integrons with 10 types of gene cassette arrays. Several non-integron-associated antibiotic resistance genes were found, and their transferability was investigated. Results showed that water sources in the Jinan region harbored a diverse community of both typical and atypical class 2 integrons, raising concerns about the overuse of antibiotics and their careless disposal into the environment.201323264021
587220.9914Characterization of the plasmids harbouring the florfenicol resistance gene floR in Glaesserella parasuis and Actinobacillus indolicus. OBJECTIVES: The aim of this study was to characterize the floR-carrying plasmids originating from Glaesserella parasuis and Actinobacillus indolicus isolated from pigs with respiratory disease in China. METHODS: A total of 125 G. parasuis and 28 A. indolicus strains collected between 2009 and 2022 were screened for florfenicol resistance. Characterization of floR-positive isolates and plasmids were determined by antimicrobial susceptibility testing, serotyping, multilocus sequence typing (MLST), conjugation and transformation assays, whole-genome sequencing (WGS), and phylogenetic analysis. RESULTS: One A. indolicus and six G. parasuis were identified as positive for floR. The six G. parasuis were assigned to four different serovars, including serovars 6, 7, 9, and unknown. In addition to strain XP11, six floR genes were located on plasmids. The six floR-bearing plasmids could be transformed into Pasteurella multocida and divided into two different types, including ∼5000 bp and ∼6000 bp plasmids. The ∼5000 bp plasmids consisting of rep, lysR, mobB, and floR genes, exhibited high similarity among Pasteurellaceae bacteria. Furthermore, the ∼6000 bp plasmids, consisting of rep, lysR, mobC, mobA/L, and floR genes, showed high similarity between G. parasuis and Actinobacillus Spp. Notably, WGS results showed that the floR modules of the two types of plasmids could be transferred and integrated into the diverse Pasteurellaceae- origined plasmids. CONCLUSION: This study firstly reported the characterization of floR-carrying plasmids from A. indolicus and a non-virulent serovar of G. parasuis in pigs in China and elucidated the transmission mechanism of the floR resistance gene among the Pasteurellaceae family.202337726088
137530.9913Characterization of integrons and their cassettes in Escherichia coli and Salmonella isolates from poultry in Korea. Ninety-nine Escherichia coli and 33 Salmonella isolates were assessed for antimicrobial susceptibility (disc diffusion test). Sulfonamide and tetracycline resistance genes were identified through PCR, and class 1 and class 2 integrons with resistance gene cassettes were identified with PCR followed by sequencing. Salmonella (63.6%) and E. coli (85.8%) isolates were multidrug resistant (resistance to 3 or more antimicrobials), and the highest incidences of resistance were observed for tetracycline, nalidixic acid, and sulfamethoxazole. The sul1, sul2, tetA, and tetB resistance determinant genes were predominant in E. coli, whereas only sul2 and tetA were identified in Salmonella isolates. In the E. coli isolates, 54 (54.5%) class 1 integrons, 6 (6.1%) class 2 integrons, and 5 (5.1%) class 1 and class 2 integrons together were detected, whereas only 3 (9.1%) integrons were found in the Salmonella serovars. Around 87% of the integrons in E. coli harbored resistance gene cassettes conferring resistance to streptomycin/spectinomycin (aadA, aminoglycoside resistance gene), trimethoprim (dfrA, dihydrofolate reductase gene), streptothricin [sat1 and sat2 (streptothricin acetyltransferase), and estX (putative esterases)]. The most common gene cassettes were aadA1+dfrA1 and dfrA1+sat2+aadA1 in class 1 and class 2 integrons, respectively. Other cassettes including aadA5+dfrA7, dfrA12+aadA2, aadA2+aadA1+dfrA12, and aadA5+aadA2/dfrA7 were also identified. Among the Salmonella serovars, Salmonella Malmoe harbored aadA1+dfrA1 and dfrA12+sat2+aadA1 genes. The aadA1, aadA2, sat2, and dfrA1 had wide variation in similarity among themselves and from previously reported genes worldwide. The diverse gene cassettes could be responsible for the prominent resistance profiles observed and a potential source for dissemination of antimicrobial resistance determinants to other bacteria.201324135609
123640.9911Molecular characterization of antimicrobial resistance in Gram-negative bacteria isolated from bovine mastitis in Egypt. The aim of this study was to characterize the genetic basis of multidrug resistance in Gram-negative bacteria isolated from bovine mastitis cases in Egypt. Multidrug resistance phenotypes were found in 34 of 112 (30.4%) Gram-negative bacterial isolates, which harbored at least one antimicrobial resistance gene. The most prevalent multidrug-resistant (MDR) species were Enterobacter cloacae (8 isolates, 7.1%), Klebsiella pneumoniae (7 isolates, 6.3%), Klebsiella oxytoca (7 isolates, 6.3%), Escherichia coli (5 isolates, 4.5%), and Citrobacter freundii (3 isolates, 2.7%). The most commonly observed resistance phenotypes were against ampicillin (97.0%), streptomycin (94.1%), tetracycline (91.2%), trimethoprim-sulfamethoxazole (88.2%), nalidixic acid (85.3%), and chloramphenicol (76.5%). Class 1 integrons were detected in 28 (25.0%) isolates. The gene cassettes within class 1 integrons included those encoding resistance to trimethoprim (dfrA1, dfrA5, dfrA7, dfrA12, dfrA15, dfrA17, and dfrA25), aminoglycosides (aadA1, aadA2, aadA5, aadA7, aadA12, aadA22, and aac(3)-Id), chloramphenicol (cmlA), erythromycin (ereA2), and rifampicin (arr-3). Class 2 integrons were identified in 6 isolates (5.4%) with three different profiles. Furthermore, the β-lactamase encoding genes, bla(TEM), bla(SHV), bla(CTX-M), and bla(OXA), the plasmid-mediated quinolone resistance genes, qnr and aac(6)-Ib-cr, and the florfenicol resistance gene, floR, were also identified. To the best of our knowledge, the results identified class 2 integrons, qnr and aac(6)-Ib-cr from cases of mastitis for the first time. This is the first report of molecular characterization for antimicrobial resistance in Gram-negative bacteria isolated from bovine mastitis in Africa.201121338385
96350.9911The detection of fosfomycin resistance genes in Enterobacteriaceae from pets and their owners. The aim of this study was to investigate the prevalence of fosfomycin resistance and molecular characteristic of fosfomycin-resistant strains isolated from companion animals and their owners. A total of 171 samples collected from pets and pet owners in a Chinese veterinary teaching hospital were screened for the presence of phenotype and genotype of fosfomycin-resistance by selective media containing fosfomycin and PCR & sequencing. Among 171 samples tested, nineteen isolates were resistant to fosfomycin. Sixteen and three of these fosfomycin-resistant isolates were positive for fosA3 and fosA genes, respectively. The fosA3 gene was detected both in chromosomes and plasmids in bacteria. All of the fosA3 gene-positive isolates except one were CTX-M producers and nearly half (7/16) of them also harbored the rmtB gene. The fosA3 gene-carrying plasmids, which were readily transferrable to recipient E. coli J53 by conjugation, conferred resistance to multiple antimicrobial agents. Genetic structures were IS26-385bp-fosA3-1810bp-IS26 (n=11) and IS26-385bp-fosA3-588bp-IS26 (n=5). Molecular typing indicated that two fosA3-positive isolates from dogs were genetically identical to the isolates from the pet owners. Our results indicated that active transmission of fosA3-mediated fosfomycin resistance has occurred among Enterobacteriaceae isolated from pets and their owners by both horizontal transfer and clonal expansion.201627599932
541860.9910Detection of optrA in the African continent (Tunisia) within a mosaic Enterococcus faecalis plasmid from urban wastewaters. OBJECTIVES: Oxazolidinone resistance is a serious limitation in the treatment of MDR Enterococcus infections. Plasmid-mediated oxazolidinone resistance has been strongly linked to animals where the use of phenicols might co-select resistance to both antibiotic families. Our goal was to assess the diversity of genes conferring phenicol/oxazolidinone resistance among diverse enterococci and to characterize the optrA genetic environment. METHODS: Chloramphenicol-resistant isolates (>16 mg/L, n = 245) from different sources (hospitals/healthy humans/wastewaters/animals) in Portugal, Angola and Tunisia (1996-2016) were selected. Phenicol (eight cat variants, fexA, fexB) or phenicol + oxazolidinone [cfr, cfr(B), optrA] resistance genes were searched for by PCR. Susceptibility (disc diffusion/microdilution), filter mating, stability of antibiotic resistance (500 bacterial generations), plasmid typing (S1-PFGE/hybridization), MLST and WGS (Illumina-HiSeq) were performed for optrA-positive isolates. RESULTS: Resistance to phenicols (n = 181, 74%) and phenicols + oxazolidinones (n = 2, 1%) was associated with the presence of cat(A-8) (40%, predominant in hospitals and swine), cat(A-7) (29%, predominant in poultry and healthy humans), cat(A-9) (2%), fexB (2%) and fexA + optrA (1%). fexA and optrA genes were co-located in a transferable plasmid (pAF379, 72 918 bp) of two ST86 MDR Tunisian Enterococcus faecalis (wastewaters) carrying several putative virulence genes. MICs of chloramphenicol, linezolid and tedizolid were stably maintained at 64, 4 and 1 mg/L, respectively. The chimeric pAF379 comprised relics of genetic elements from different Gram-positive bacteria and origins (human/porcine). CONCLUSIONS: To the best of our knowledge, we report the first detection of optrA in an African country (Tunisia) within a transferable mosaic plasmid of different origins. Its identification in isolates from environmental sources is worrisome and alerts for the need of a concerted global surveillance on the occurrence and spread of optrA.201729029072
199270.9910Antimicrobial Resistance Genes, Cassettes, and Plasmids Present in Salmonella enterica Associated With United States Food Animals. The ability of antimicrobial resistance (AR) to transfer, on mobile genetic elements (MGEs) between bacteria, can cause the rapid establishment of multidrug resistance (MDR) in bacteria from animals, thus creating a foodborne risk to human health. To investigate MDR and its association with plasmids in Salmonella enterica, whole genome sequence (WGS) analysis was performed on 193 S. enterica isolated from sources associated with United States food animals between 1998 and 2011; 119 were resistant to at least one antibiotic tested. Isolates represented 86 serotypes and variants, as well as diverse phenotypic resistance profiles. A total of 923 AR genes and 212 plasmids were identified among the 193 strains. Every isolate contained at least one AR gene. At least one plasmid was detected in 157 isolates. Genes were identified for resistance to aminoglycosides (n = 472), β-lactams (n = 84), tetracyclines (n = 171), sulfonamides (n = 91), phenicols (n = 42), trimethoprim (n = 8), macrolides (n = 5), fosfomycin (n = 48), and rifampicin (n = 2). Plasmid replicon types detected in the isolates were A/C (n = 32), ColE (n = 76), F (n = 43), HI1 (n = 4), HI2 (n = 20), I1 (n = 62), N (n = 4), Q (n = 7), and X (n = 35). Phenotypic resistance correlated with the AR genes identified in 95.4% of cases. Most AR genes were located on plasmids, with many plasmids harboring multiple AR genes. Six antibiotic resistance cassette structures (ARCs) and one pseudo-cassette were identified. ARCs contained between one and five resistance genes (ARC1: sul2, strAB, tetAR; ARC2: aac3-iid; ARC3: aph, sph; ARC4: cmy-2; ARC5: floR; ARC6: tetB; pseudo-ARC: aadA, aac3-VIa, sul1). These ARCs were present in multiple isolates and on plasmids of multiple replicon types. To determine the current distribution and frequency of these ARCs, the public NCBI database was analyzed, including WGS data on isolates collected by the USDA Food Safety and Inspection Service (FSIS) from 2014 to 2018. ARC1, ARC4, and ARC5 were significantly associated with cattle isolates, while ARC6 was significantly associated with chicken isolates. This study revealed that a diverse group of plasmids, carrying AR genes, are responsible for the phenotypic resistance seen in Salmonella isolated from United States food animals. It was also determined that many plasmids carry similar ARCs.201931057528
108880.9910Detection and Molecular Characterization of Escherichia coli Strains Producers of Extended-Spectrum and CMY-2 Type Beta-Lactamases, Isolated from Turtles in Mexico. Multidrug-resistant bacteria are a growing problem in different environments and hosts, but scarce information exists about their prevalence in reptiles. The aim of this study was to analyze the resistance mechanisms, molecular typing, and plasmid content of cefotaxime-resistant (CTX(R)) Escherichia coli isolates recovered from cloacal samples of 71 turtles sheltered in a herpetarium in Mexico. CTX(R)-E. coli were recovered in 11 of 71 samples (15.5%), and one isolate/sample was characterized. Extended-spectrum β-lactamase (ESBL)-producing E. coli isolates were detected in four samples (5.6%): two strains carried the blaCTX-M-2 gene (phylogroup D and ST2732) and two contained the blaCTX-M-15 gene (phylogroup B1 and lineages ST58 and ST156). The blaCMY-2 gene was detected by PCR in E. coli isolates of eight samples (9.8%) (one of them also carried blaCTX-M-2); these isolates were distributed into phylogroups A (n = 1), B1 (n = 6), and D (n = 1) and typed as ST155, ST156, ST2329, and ST2732. Plasmid-mediated quinolone resistance (PMQR) genes were detected in five isolates [aac(6')Ib-cr, qnrA, qnrB19, and oqxB]. From three to five replicon plasmids were detected among the strains, being IncFIB, IncI1, IncFrep, and IncK the most prevalent. ESBL or pAmpC genes were transferred by conjugation in four strains, and the blaCTX-M-15 and blaCMY-2 genes were localized in IncFIB or IncI1 plasmids by Southern blot hybridization assays. Class 1 and/or class 2 integrons were detected in eight strains with six different structures of gene cassette arrays. Nine pulsed-field gel electrophoresis patterns were found among the 11 studied strains. To our knowledge, this is the first detection of ESBL, CMY-2, PMQR, and mobile determinants of antimicrobial resistance in E. coli of turtle origin, highlighting the potential dissemination of multidrug-resistant bacteria from these animals to other environments and hosts, including humans.201627482752
199190.9909A strain defined as a novel species in the Acinetobacter genus co-harboring chromosomal associated tet(X3) and plasmid associated bla (NDM-1) from a beef cattle farm in Hebei, China. INTRODUCTION: The co-existence phenomenon of antibiotic resistance genes (ARGs), particularly of last-resort antibiotics in multi-drug resistant (MDR) bacteria, is of particular concern in the least studied bacterial species. METHODS: In 2023, strain M2 was isolated from the sludge sample at a commercial bovine farm in Hebei province, China, using a MacConkey plate containing meropenem. PCR amplification and Sanger sequencing verified it co-carrying bla (NDM) and tet(X) genes. It was classified within the Acinetobacter genus by MALDI-TOF-MS and 16S rDNA analyses. Whole-genome sequencing (WGS) was performed on the Oxford Nanopore platform, with species-level identification via ANI and dDDH. Antimicrobial susceptibility testing was performed against 20 antibiotics. Conjugation assays employed the filter-mating method using E. coli J53 and Salmonella LGJ2 as recipients. RESULTS: This strain was confirmed as a novel species of Acinetobacter genus, showing resistance to meropenem, ampicillin, ceftazidime, cefepime, gentamicin, kanamycin, fosfomycin, imipenem, ertapenem, and tetracycline. Despite carrying tet(X3), it remained susceptible to tigecycline, omadacycline, and doxycycline. The genome carried 11 ARG types, multiple metal resistance genes (MRGs), and virulence factor (VF) genes. The bla (NDM-1) was located in a skeleton, ISAba125-bla (NDM-1)-ble (MBL)-trpF, which was carried by an ISAba14-mediated rolling-circle-like structure in pM2-2-NDM-1 (rep_cluster_481). Integrative and conjugative element (ICE) and multiple pdif modules (driven by the XerCD site-specific recombination (XerCD SSR) system), which were associated with the mobilization of resistance determinants, were identified in this plasmid. Chromosomal tet(X3) was mediated by ISVsa3, forming a skeleton, ISVsa3-XerD-tet (X3)-res-ISVsa3. DISCUSSION: The co-occurrence of bla (NDM) and tet(X) in a novel species of the Acinetobacter genus hints that substantial undiscovered bacteria co-carrying high-risk ARGs are concealing in the agroecological system, which should cause particular concern.202540673007
1752100.9909Genetic Characterization of a Linezolid- and Penicillin-Resistant Enterococcus hirae Isolate Co-Harboring poxtA and pbp5fm. Linezolid and penicillin are critical for treating multidrug resistant (MDR) Gram-positive infections, but the emergence of resistance to both seriously threatens public health. Here, we first report the cocarrying poxtA (oxazolidinone resistance) and pbp5fm (β-lactam resistance) genes by the plasmid in a strain of Enterococcus hirae HDC14-2 derived from porcine. The isolate also exhibits MDR phenotypes to phenicols, oxazolidinones, tetracyclines, β-lactams, aminoglycosides, macrolides, and lincosamides. Whole-genome sequencing (WGS) revealed these resistance genes, along with tet(L), tet(M), catA, erm(B), aac(6)-aph(2"), aadE, spw, lsa(E), lnu(B), sat4, and aphA3, were clustered in a novel MDR region flanked by IS1216 elements on plasmid pHDC14-2.133K. This IS1216-bounded MDR region formed translocatable units (TUs), including an IS1216-poxtA TU that was also identified on a secondary plasmid, pHDC14-2.27K. Functional assays demonstrated the excisability and mobility of these TUs, indicating its potential ability integration into other plasmids or chromosomes. Critically, electrotransformation confirmed the transfer of pHDC14-2.27K (poxtA-carrying) to Enterococcus faecalis JH2-2, with retained TU activity and minimal fitness cost. This study provides the evidence of colocalized poxtA and pbp5fm on plasmids in enterococci, highlighting their role in disseminating pan-resistance among bacteria. Although E. hirae is not an important pathogenic bacterium to humans and animals, but its potential risk to horizontally spread of these resistance genes important in medicine still cannot be ignored.202540692874
1511110.9908Characterization of an Extensively Drug-Resistant Salmonella Kentucky ST198 Co-Harboring cfr, mcr-1 and tet(A) Variant from Retail Chicken Meat in Shanghai, China. The emergence of extensively drug-resistant (XDR) foodborne pathogens poses grave threats to food safety. This study characterizes the genome of an XDR Salmonella Kentucky isolate (Sal23C1) co-harboring cfr, mcr-1 and tet(A) from Shanghai chicken meat in 2022, which was the only isolate co-harboring these three key resistance genes among 502 screened Salmonella isolates. Genomic analysis revealed that the multidrug resistance gene cfr, which confers resistance to phenicols, lincosamides, oxazolidinones, pleuromutilins and streptogramin A, was identified within a Tn3-IS6-cfr-IS6 structure on the transferable plasmid p3Sal23C1 (32,387 bp), showing high similarity to the Citrobacter braakii plasmid pCE32-2 (99% coverage, 99.98% identity). Concurrently, the mcr-1 gene resided in a pap2-mcr-1 structure on the transferable IncI2 plasmid p2Sal23C1 (63,103 bp). Notably, both genes could be co-transferred to recipient bacteria via conjugative plasmids at frequencies of (1.15 ± 0.98) × 10(-6). Furthermore, a novel ~79 kb multidrug resistance region (MRR) chromosomally inserted at the bcfH locus was identified, carrying fosA3, mph(A), rmtB, qnrS1 and bla(CTX-M-55). Additionally, a novel Salmonella Genomic Island 1 variant (SGI1-KI) harbored aadA7, qacEΔ1, sul1 and the tet(A) variant. The acquisition of these antibiotic resistance genes in this isolate enhanced bacterial resistance to 21 antimicrobials, including resistance to the critical last-resort antibiotics tigecycline and colistin, which left virtually no treatment options for potential infections. Taken together, this is the first comprehensive genomic report of an XDR poultry-derived Salmonella Kentucky isolate co-harboring cfr, mcr-1 and the tet(A) variant. The mobility of these resistance genes, facilitated by IS6 elements and conjugative plasmids, underscores significant public health risks associated with such isolates in the food chain.202540941142
1321120.9908Antimicrobial Resistance and Resistance Genes in Aerobic Bacteria Isolated from Pork at Slaughter. The aim of this study was to investigate the phenotypic and genotypic antimicrobial resistance, integrons, and transferability of resistance markers in 243 aerobic bacteria recovered from pork at slaughter in the People's Republic of China. The organisms belonged to 22 genera of gram-negative bacteria (92.2%) and gram-positive bacteria (7.8%). High levels of resistance were detected to tetracycline, trimethoprim-sulfamethoxazole, and ampicillin (36.2 to 54.3%), and lower levels were detected to nitrofurantoin, cefotaxime, gentamicin, ciprofloxacin, and chloramphenicol (7.8 to 29.2%). Across species, genes conferring antimicrobial resistance were observed with the following frequencies: blaTEM, 40.7%; blaCMY-2, 15.2%; blaCTX-M, 11.5%; sul2, 27.2%; sul1, 14.4%; tet(A), 5.4%; tet(L), 5.4%; tet(M), 5.0%; tet(E), 3.7%; tet(C), 3.3%; tet(S), 2.5%; and tet(K), 0.8%. Various antimicrobial resistance genes were found in new carriers: blaTEM in Lactococcus garvieae, Myroides odoratimimus, Aeromonas hydrophila, Staphylococcus sciuri, Raoultella terrigena, Macrococcus caseolyticus, Acinetobacter ursingii, Sphingobacterium sp., and Oceanobacillus sp.; blaCMY-2 in Lactococcus lactis, Klebsiella oxytoca, Serratia marcescens, Acinetobacter baumannii, and Myroides phaeus; tet(L) in M. caseolyticus; sul1 in Vibrio cincinnatiensis; sul2 in Acinetobacter bereziniae, Acinetobacter johnsonii, and V. cincinnatiensis; and the class 1 integron and gene cassette aadA2 in V. cincinnatiensis. Approximately 6.6% of isolates contained class 1 integrons, and one isolate harbored class 2 integrons. Plasmid associated intI1 and androgen receptor- encoding genes were transferred into Escherichia coli J53 and E. coli DH5α by conjugation and transformation experiments, respectively. Our study highlights the importance of aerobic bacteria from pork as reservoirs for antimicrobial resistance genes and mobile genetic elements that can readily be transferred intra- and interspecies.201627052863
1174130.9908Identification of plasmid-mediated quinolone resistance qnr genes in multidrug-resistant Gram-negative bacteria from hospital wastewaters and receiving waters in the Jinan area, China. We investigated the prevalence of plasmid-mediated quinolone resistance (PMQR) qnr genes by the polymerase chain reaction (PCR) in antibiotic-resistant bacteria isolates collected from aquatic environments in Jinan during 2 years (2008.3-2009.11). Genes were identified to variant level by PCR restriction fragment length polymorphism analysis or sequencing. qnrA1, qnrB2, qnrB4, qnrB6, qnrB9, qnrS1, and the new qnrB variant qnrB26 were detected in 31 strains from six genera (Klebsiella spp., Escherichia coli, Enterobacter spp., Proteus spp., Shigella spp., and Citrobacter spp.), four of which contained double qnr genes. Other PMQR genes, aac(6')-Ib-cr and qepA, were found in 12 (38.7%) and 5 (16.1%) of 31 isolates, respectively; while qepA was found in Shigella spp. for the first time. Eight types of β-lactamase genes and eight other types of resistance genes were also present in the 31 qnr-positive isolates. The detection rate for five β-lactamase genes (blaTEM, blaCTX, ampR, blaDHA, and blaSHV) was >45%. Class 1 integrons and complex class 1 integrons were prevalent in these strains, which contained 15 different gene cassette arrays and 5 different insertion sequence common region 1 (ISCR1)-mediated downstream structures. qnrA1, qnrB2, and qnrB6 were present in three ISCR1-mediated downstream structures: qnrA1-ampR, sapA-like-qnrB2, and sdr-qnrB6. We also analyzed the horizontal transferability of PMQR genes and other resistance determinants. The qnr genes and some integrons and resistance genes from 18 (58.1%) of the 31 qnr-positive strains could be transferred to E. coli J53 Azi(R) or E. coli DH5α recipient strains using conjugation or transformation methods. The results showed that a high number of qnr genes were associated with other resistance genes in aquatic environments in Jinan. This suggests that we should avoid over-using antibiotics and monitor aquatic environments to control the spread of antibiotic resistance genes.201323844849
1235140.9908Characterization of integrons and antimicrobial resistance genes in clinical isolates of Gram-negative bacteria from Palestinian hospitals. Sixty Gram-negative bacterial isolates were collected from Palestinian hospitals in 2006. Thirty-two (53.3%) isolates showed multidrug resistance phenotypes. PCR and DNA sequencing were used to characterize integrons and antimicrobial resistance genes. PCR screening showed that 19 (31.7%) and five (8.3%) isolates were positive for class 1 and class 2 integrons, respectively. DNA-sequencing results for the captured antimicrobial resistance gene cassettes within class 1 integrons identified the following genes: dihydrofolate reductases, dfrA1, dfrA5, dfrA7, dfrA12, dfrA17 and dfrA25; aminoglycoside adenyltransferases, aadA1, aadA2, aadA5, aadA12 and aadB; aminoglycoside acetyltransferase, aac(6')-Ib; and chloramphenicol resistance gene, cmlA1. ESBL were identified in 25 (41.7%) isolates. The identified ESBL were bla(CTX-M-15), bla(CTX-M-56), bla(OXA-1), bla(SHV-1), bla(SHV-12), bla(SHV-32) and bla(TEM-1) genes. Moreover, we characterized the plasmid-mediated quinolone resistance genes, aac(6')-Ib-cr and qnrB2, which were detected in seven (11.7%) and two (3.3%) isolates, respectively. In this study various types of antibiotic resistance genes have been identified in Gram-negative bacteria from Palestinian hospitals, many of which are reported in the Middle East area for the first time.200919903259
1504150.9908Identification and Genomic Analyses of a Multidrug Resistant Avian Pathogenic Escherichia coli Coharboring mcr-1, bla (TEM-176) and bla (CTX-M-14) Genes. The emergence and transmission of the colistin-resistance gene mcr and extended-spectrum β-lactamase (ESBL) encoding genes pose a significant threat to global public health. In recent years, it has been reported that mcr-1 and ESBL genes can coexist in single bacteria strain. The objective of this study was to characterize a multidrug-resistant (MDR) avian pathogenic Escherichia coli (APEC) isolate carrying mcr and ESBL encoding genes in China. A total of 200 APEC isolates were collected for antimicrobial susceptibility testing by Kirby-Bauer (K-B) disk method. The MDR strain EC012 were then further analyzed for minimum inhibitory concentrations, antimicrobials resistance genes (ARGs) detection, conjugation, and whole-genome sequencing (WGS). Among all APEC isolates determined by K-B disk method, strain EC012 was resistant to almost all the antimicrobials, including polymyxin B, cefotaxime, and ceftazidime. Moreover, EC012 harbored ARGs mcr-1, bla (TEM-176), and bla (CTX-M-14). WGS analysis revealed that EC012 belonged to epidemic APEC serotype O1:H16 and multilocus sequence type ST295. EC012 consisted of one chromosome and six plasmids, encoding a broad ARGs. The bla (CTX-M-14), mcr-1 or bla (TEM-176) genes were located on conjugative plasmids pEC012-1 or pEC012-5, respectively. These plasmids were successfully transferred to transconjugants and resulted in the resistance to polymyxin B, cefotaxime, and ceftazidime. This study indicated that APEC was a potential reservoir of colistin-resistance gene mcr-1 and ESBL encoding genes, and highlighted the necessity for enhanced monitoring of ARGs dissemination among bacteria from different origins.202440303132
2019160.9908Characterization of small plasmids carrying florfenicol resistance gene floR in Actinobacillus pleuropneumoniae and Pasteurella multocida isolates from swine in China. Actinobacillus pleuropneumoniae and Pasteurella multocida are two important bacterial pathogens in swine industry. In the present study, resistance profiles of nine commonly used antibiotics of A. pleuropneumoniae and P. multocida isolates of swine origin from different regions of China were investigated by determination of minimum inhibitory concentrations (MICs). In addition, genetic relationship of the florfenicol-resistant A. pleuropneumoniae and P. multocida isolates was determined by pulsed-field gel electrophoresis (PFGE). The genetic basis of florfenicol resistance in these isolates were explored by floR detection and whole genome sequencing. High resistance rates (>25%) of florfenicol, tetracycline and trimethoprim- sulfamethoxazole were observed for both bacteria. No ceftiofur- and tiamulin- resistant isolates were detected. Furthermore, all the 17 florfenicol-resistant isolates (nine for A. pleuropneumoniae and eight for P. multocida) were positive for floR gene. The presence of similar PFGE types in these isolates suggested that clonal expansion of some floR-producing strains occurred in the pig farms from same regions. WGS and PCR screening showed that three plasmids, named pFA11, pMAF5, and pMAF6, were the cargos of the floR genes in the 17 isolates. Plasmid pFA11 exhibited novel structure and carried several resistance genes, including floR, sul2, aacC2d, strA, strB, and bla (ROB - 1). Plasmids pMAF5 and pMAF6 were presented in A. pleuropneumoniae and P. multocida isolates from different regions, suggesting horizontal transfer of the two plasmids are important for the floR dissemination in these Pasteurellaceae pathogens. Further studies of florfenicol resistance and its transfer vectors in Pasteurellaceae bacteria of veterinary origin are warranted.202336793377
1505170.9907New insights on mcr-1-harboring plasmids from human clinical Escherichia coli isolates. Mobile colistin resistance (mcr) genes were described recently in Gram-negative bacteria including carbapenem-resistant Enterobacterales. There are ten mcr genes described in different Gram-negative bacteria, however, Escherichia coli harboring mcr-1 gene is by far the most frequent combination. In Argentina, mcr-1 gene was characterized only on plasmids belonging to IncI2 group. The aim of this work was to get new insights of mcr-1-harboring plasmids from E. coli. Eight E. coli isolates from a larger collection of 192 clinical E. coli isolates carrying the mcr-1 gene were sequenced using next generation technologies. Three isolates belonged to ST131 high-risk clone, and five to single ST, ST38, ST46, ST226, ST224, and ST405. Eight diverse mcr-1-harboring plasmids were analyzed: IncI2 (1), IncX4 (3), IncHI2/2A (3) and a hybrid IncFIA/HI1A/HI1B (1) plasmid. Plasmids belonging to the IncI2 (n = 1) and IncX4 (n = 3) groups showed high similarity with previously described plasmids. Two IncHI2/HI2A plasmids, showed high identity between them, while the third, showed several differences including additional resistance genes like tet(A) and floR. One IncFIA/H1A/H1B hybrid plasmid was characterized, highly similar to pSRC27-H, a prototype plasmid lacking mcr genes. mcr-1.5 variant was found in four plasmids with three different Inc groups: IncI2, IncHI2/HI2A and the hybrid FIA/HI1A/HI1B plasmid. mcr-1.5 variant is almost exclusively described in our country and with a high frequency. In addition, six E. coli isolates carried three allelic variants codifying for CTX-M-type extended-spectrum-β-lactamases: blaCTX-M-2 (3), blaCTX-M-65 (2), and blaCTX-M-14 (1). It is the first description of mcr-1 harboring plasmids different to IncI2 group in our country. These results represents new insights about mcr-1 harboring plasmids recovered from E. coli human samples from Argentina, showing different plasmid backbones and resistance gene combinations.202438408071
1377180.9907Characterization and Horizontal Transfer of Antimicrobial Resistance Genes and Integrons in Bacteria Isolated from Cooked Meat Products in China. The aim of this study was to investigate antimicrobial resistance and the presence and transferability of corresponding resistance genes and integrons in bacteria isolated from cooked meat samples in the People's Republic of China. A total of 150 isolates (22 species belonging to 15 genera) were isolated from 49 samples. Resistance of these isolates to antimicrobials was commonly observed; 42.7, 36.0, and 25.3% of the isolates were resistant to tetracycline, streptomycin, and ampicillin, respectively. Multidrug resistance was observed in 41 (27.3%) of the isolates. Sixteen resistance genes, i.e., bla(TEM-1) and bla(CTX-M-14) (β-lactams), aac(3)-IIa (gentamicin), strA and strB (streptomycin), qnrB and qnrS (fluoroquinolone), sul1, sul2, and sul3 (sulfamethoxazole), cat1 and cat2 (chloramphenicol), and tetM, tetA, tetS, and tetB (tetracycline), were found in 54 isolates. One isolate of Pseudomonas putida carried qnrB, and sequence analysis of the PCR product revealed 96% identity to qnrB2. The qnr genes were found coresiding and were cotransferred with bla genes in two isolates. Twelve isolates were positive for the class 1 integrase gene, and four isolates carried the class 2 integrase gene. However, no class 3 integrase gene was detected. One isolate of Proteus mirabilis carried dfrA32-ereA-aadA2, and this unusual array could be transferred to Escherichia coli. Nonclassic class 1 integrons lacking qacEΔ1 and sul1 genes were found in 2 of the 12 intI1-positive isolates. Our results revealed the presence of multidrug-resistant bacteria in cooked meats and the presence and transferability of resistance genes in some isolates, suggesting that cooked meat products may act as reservoirs of drug-resistant bacteria and may facilitate the spread of resistance genes.201729148877
1507190.9907Characterization of Five Escherichia coli Isolates Co-expressing ESBL and MCR-1 Resistance Mechanisms From Different Origins in China. Present study characterized five Escherichia coli co-expressing ESBL and MCR-1 recovered from food, food-producing animals, and companion animals in China. Antimicrobial susceptibility tests, conjugation experiments, and plasmid typing were performed. Whole genome sequencing (WGS) was undertaken for all five isolates using either PacBio RS II or Illumina HiSeq 2500 platforms. The cefotaxime and colistin resistance encoded by bla (CTX-M) and mcr-1 genes, respectively, was transferable by conjugation either together or separately for all five strains. Interestingly, the ESBL and mcr-1 genes could be co-selected by cefotaxime, while the colistin only selected the mcr-1-carrying plasmids during the conjugation experiments. Five E. coli sequence types (ST88, ST93, ST602, ST162, and ST457) were detected. Although diverse plasmid profiles were identified, IncI2, IncFIB, and IncFII plasmid types were predominant. These five clonally unrelated isolates harbored the mcr-1 gene located on similar plasmid backbones, which showed high nucleotide similarity to plasmid pHNSHP45. The mcr-1 gene can be co-transmitted with bla (CTX-M) genes through IncI2 plasmids with or without ISApl1 in our study. Characterization of these co-existence ESBL and mcr-1 isolates extends our understanding on the dissemination of these resistance markers among bacteria of diverse origins.201931555232