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540700.9895Resistance mechanisms and tedizolid susceptibility in clinical isolates of linezolid-resistant bacteria in Japan. OBJECTIVES: Studies combining linezolid resistance mechanisms and tedizolid susceptibility in linezolid-resistant clinical isolates are scarce. This study investigated the linezolid resistance mechanisms and tedizolid susceptibility of linezolid-resistant strains isolated clinically in Japan. METHODS: We analysed 25 linezolid-resistant strains of Enterococcus faecium and Enterococcus faecalis isolated from Japanese hospitals between 2015 and 2021. MICs of linezolid and tedizolid were determined using the agar plate dilution method. Each 23S rRNA copy was amplified by PCR, sequenced and analysed for mutations. The linezolid resistance genes cfr, poxtA, optrA, fexA and fexB were also detected by PCR. RESULTS: Drug susceptibility tests revealed that five linezolid-resistant E. faecium isolates had low (≤1 mg/L) tedizolid MICs. Resistance mechanisms included the G2576T mutation in 23S rRNA, the T2504A mutation and the resistance genes optrA, fexA and fexB. The T2504A mutation was identified in one E. faecium isolate, which exhibited linezolid and tedizolid MICs of 64 and 32 mg/L, respectively. CONCLUSIONS: Some linezolid-resistant isolates demonstrated low (≤1 mg/L) tedizolid MICs. To determine whether tedizolid susceptibility testing should be performed on linezolid-resistant isolates, more linezolid-resistant isolates should be collected and tested for tedizolid MICs. Tedizolid MICs were 2-3 doubling dilutions lower than linezolid MICs. The results of this study suggest that future research should investigate whether the T2504A mutation contributes to tedizolid resistance. To our knowledge, this is the first study to report tedizolid susceptibility in E. faecium with the T2504A mutation and in isolate harbouring this mutation.202540463587
541810.9887Detection 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
587520.9885Detection of the staphylococcal multiresistance gene cfr in Macrococcus caseolyticus and Jeotgalicoccus pinnipedialis. OBJECTIVES: To investigate the presence and the genetic environment of the multiresistance gene cfr in Jeotgalicoccus pinnipedialis and Macrococcus caseolyticus from pigs. METHODS: A total of 391 bacterial isolates with florfenicol MICs ≥16 mg/L were obtained from nasal swabs of 557 individual pigs; of these, 75 Gram-positive isolates other than staphylococci and enterococci were screened by PCR for the presence of known florfenicol resistance genes. Species assignments of the cfr-carrying isolates were based on the results of biochemical profiling and 16S rDNA sequencing. The locations of the cfr gene were determined by Southern blotting. Regions flanking each cfr gene were sequenced by a modified random primer walking strategy, and the transferability of cfr was assessed by electrotransformation. RESULTS: Two M. caseolyticus isolates and one J. pinnipedialis isolate were cfr positive. The cfr gene was located either on a 7057 bp plasmid, pSS-03, which was widely distributed among staphylococci of pig origin, or on the ∼53 kb plasmid pJP1. The region of pJP1 that included the cfr gene and the adjacent IS21-558, showed 99.7% identity to the corresponding region of plasmid pSCFS3. In addition, the genes aadD + aacA-aphD, ble and erm(C), coding for aminoglycoside, bleomycin and macrolide-lincosamide-streptogramin B resistance, respectively, were also identified on plasmid pJP1. CONCLUSIONS: This study showed that plasmids carrying the multidrug resistance gene cfr are present in two new genera of commensal and environmental bacteria, Macrococcus and Jeotgalicoccus. This observation underlines the role of commensal and environmental flora in the dissemination of clinically important resistance genes, such as cfr.201222577104
200130.9885Identification of plasmids co-carrying cfr(D)/optrA and cfr(D2)/poxtA linezolid resistance genes in two Enterococcus avium isolates from swine brain. Oxazolidinones are critically important antibiotics to treat human infections caused by multidrug-resistant bacteria, therefore the occurrence of linezolid-resistant enterococci from food-producing animals poses a serious risk to human health. In this study, Enterococcus avium 38157 and 44917 strains, isolated from the brain of two unrelated piglets, were found to carry the linezolid resistance genes cfr(D)-optrA, and cfr(D2)-poxtA, respectively. Whole genome sequencing analysis of E. avium 38157 revealed that the genes were co-located on the 36.5-kb pEa_cfr(D)-optrA plasmid showing high identity with the pAT02-c of Enterococcus faecium AT02 from pet food. The optrA region, was 99% identical to the one of the pAv-optrA plasmid from a bovine Aerococcus viridans strain, whereas the cfr(D) genetic context was identical to that of the plasmid 2 of E. faecium 15-307.1. pEa_cfr(D)-optrA was not transferable to enterococcal recipients. In E. avium 44917 a cfr(D)-like gene, named cfr(D2), and the poxtA gene were co-located on the transferable 42.6-kb pEa-cfr(D2)-poxtA plasmid 97% identical to the Tn6349 transposon of the human MRSA AOUC-0915. The cfr(D2) genetic context, fully replaced the Tn6644 that in S. aureus AOUC-0915 harbor the cfr gene. In conclusion, this is, the best of our knowledge, the first report of the new cfr(D2) gene variant. The occurrence of plasmids co-carrying two linezolid resistance genes in enterococci from food-producing animals needs close surveillance to prevent their spread to human pathogens.202337116421
540540.9883Characterization of florfenicol resistance genes in the coagulase-negative Staphylococcus (CoNS) isolates and genomic features of a multidrug-resistant Staphylococcus lentus strain H29. BACKGROUND: With the wide use of florfenicol to prevent and treat the bacterial infection of domestic animals, the emergence of the florfenicol resistance bacteria is increasingly serious. It is very important to elucidate the molecular mechanism of the bacteria's resistance to florfenicol. METHODS: The minimum inhibitory concentration (MIC) levels were determined by the agar dilution method, and polymerase chain reaction was conducted to analyze the distribution of florfenicol resistance genes in 39 CoNS strains isolated from poultry and livestock animals and seafood. The whole genome sequence of one multidrug resistant strain, Staphylococcus lentus H29, was characterized, and comparative genomics analysis of the resistance gene-related sequences was also performed. RESULTS: As a result, the isolates from the animals showed a higher resistance rate (23/28, 82.1%) and much higher MIC levels to florfenicol than those from seafood. Twenty-seven animal isolates carried 37 florfenicol resistance genes (including 26 fexA, 6 cfr and 5 fexB genes) with one carrying a cfr gene, 16 each harboring a fexA gene, 5 with both a fexA gene and a fexB gene and the other 5 with both a fexA gene and a cfr gene. On the other hand, all 11 isolates from seafood were sensitive to florfenicol, and only 3 carried a fexA gene each. The whole genome sequence of S. lentus H29 was composed of a chromosome and two plasmids (pH29-46, pH29-26) and harbored 11 resistance genes, including 6 genes [cfr, fexA, ant(6)-Ia, aacA-aphD, mecA and mph(C)] encoded on the chromosome, 4 genes [cfr, fexA, aacA-aphD and tcaA] on pH29-46 and 1 gene (fosD) on pH29-26. We found that the S. lentus H29 genome carried two identical copies of the gene arrays of radC-tnpABC-hp-fexA (5671 bp) and IS256-cfr (2690 bp), of which one copy of the two gene arrays was encoded on plasmid pH29-46, while the other was encoded on the chromosome. CONCLUSIONS: The current study revealed the wide distribution of florfenicol resistance genes (cfr, fexA and fexB) in animal bacteria, and to the best of our knowledge, this is the first report that one S. lentus strain carried two identical copies of florfenicol resistance-related gene arrays.202133413633
151150.9883Characterization 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
545460.9882Identification of an Enterococcus faecium strain isolated from raw bovine milk co-harbouring the oxazolidinone resistance genes optrA and poxtA in China. Oxazolidinones are potent antimicrobial agents used to treat human infections caused by multidrug-resistant Gram-positive bacteria. The growing resistance to oxazolidinones poses a significant threat to public health. In August 2021, a linezolid-resistant Enterococcus faecium BN83 was isolated from a raw milk sample of cow in Inner Mongolia, China. This isolate exhibited a multidrug resistance phenotype and was resistant to most of drugs tested including linezolid and tedizolid. PCR detection showed that two mobile oxazolidinones resistance genes, optrA and poxtA, were present in this isolate. Whole genome sequencing analysis revealed that the genes optrA and poxtA were located on two different plasmids, designated as pBN83-1 and pBN83-2, belonging to RepA_N and Inc18 families respectively. Genetic context analysis suggested that optrA gene on plasmid pBN83-1 was located in transposon Tn6261 initially found in E. faecalis. Comprehensive analysis revealed that Tn6261 act as an important horizontal transmission vector for the spread of optrA in E. faecium. Additionally, poxtA-bearing pBN83-2 displayed high similarity to numerous plasmids from Enterococcus of different origin and pBN83-2-like plasmid represented a key mobile genetic element involved in movement of poxtA in enterococcal species. The presence of optrA- and poxtA-carrying E. faecium in raw bovine milk represents a public health concern and active surveillance is urgently warranted to investigate the prevalence of oxazolidinone resistance genes in animal-derived food products.202438718528
96370.9880The 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
540880.9879Identification and pathogenicity of an XDR Streptococcus suis isolate that harbours the phenicol-oxazolidinone resistance genes optrA and cfr, and the bacitracin resistance locus bcrABDR. One hundred and seven Streptococcus suis isolates were collected from healthy pigs or asymptomatic carriers in Jiangsu, China in 2016-2017. Thirty-eight percent of the isolates were linezolid-resistant and all carried the optrA gene. Among them, one isolate, SFJ44, was resistant to all 20 of the antibiotics tested, except for ceftiofur, and thus exhibited an extensively-drug-resistant phenotype. This isolate carried the optrA gene and the bacitracin resistance locus bcrABDR on an antibiotic-resistance-associated genomic island (ARGI1), and harboured the resistance genes cfr, aadE, sat4, spw-like, aphA3, mef(A), msr(D), erm(A)-like, erm(B), tetAB(P)', tet(M) and catQ on ARGI2∼4. The IS1216E-bcrABDR-ISEnfa1 segment showed >99.9% sequence identity to corresponding sequences from other species. The cfr gene was located on ARGI4, and two IS6 family insertion sequences, IS1216E and ISTeha2, were found upstream and downstream of cfr-ΔISEnfa5, respectively. A circular intermediate of bcrABDR-ISEnfa1 was detected, suggesting the role of ISEnfa1 in dissemination of bcrABDR. Other antibiotic resistance genes might be acquired from different Gram-positive pathogens. Infection of zebrafish showed that SFJ44 exhibited a virulence level comparable to serotype 2 hypervirulent strain SC070731, highlighting the need for surveillance of the pathogenicity of multi-drug-resistant S. suis isolates. This is the first report of the co-existence of optrA and cfr, and of the bcrABDR locus in streptococci. As it has been suggested that S. suis may act as an antibiotic resistance reservoir contributing to the spread of resistance genes to major streptococcal pathogens, the potential dissemination of these resistance genes among Gram-positive bacteria is of concern and routine surveillance should be strengthened.201930981924
542290.9878Analysis of Resistance to Florfenicol and the Related Mechanism of Dissemination in Different Animal-Derived Bacteria. Bacterial resistance to antibiotics has become an important concern for public health. This study was aimed to investigate the characteristics and the distribution of the florfenicol-related resistance genes in bacteria isolated from four farms. A total of 106 florfenicol-resistant Gram-negative bacilli were examined for florfenicol-related resistance genes, and the positive isolates were further characterized. The antimicrobial sensitivity results showed that most of them (100, 94.33%) belonged to multidrug resistance Enterobacteriaceae. About 91.51% of the strains carried floR gene, while 4.72% carried cfr gene. According to the pulsed-field gel electrophoresis results, 34 Escherichia coli were subdivided into 22 profiles, the genetic similarity coefficient of which ranged from 80.3 to 98.0%. The multilocus sequence typing (MLST) results revealed 17 sequence types (STs), with ST10 being the most prevalent. The genome sequencing result showed that the Proteus vulgaris G32 genome consists of a 4.06-Mb chromosome, a 177,911-bp plasmid (pG32-177), and a 51,686-bp plasmid (pG32-51). A floR located in a drug-resistant region on the chromosome of P. vulgaris G32 was with IS91 family transposase, and the other floR gene on the plasmid pG32-177 was with an ISCR2 insertion sequence. The cfr gene was located on the pG32-51 flanked by IS26 element and TnpA26. This study suggested that the mobile genetic elements played an important role in the replication of resistance genes and the horizontal resistance gene transfer.202032903722
5417100.9878Molecular characteristics of oxazolidinone resistance in enterococci from a multicenter study in China. BACKGROUND: Linezolid-resistant enterococci pose great challenges in clinical practice. The aim of this study is to study the mechanisms underlying the resistance and genetic environment of antimicrobial resistance gene of linezolid-resistant enterococci. RESULTS: The linezolid MICs of 16 enterococci were 4 mg/L to 16 mg/L. Four strains belonged to multi-drug resistant (MDR) bacteria. The sequence types (STs) of 13 enterococci strains performed WGS were diverse: 3 ST476, 1 ST86, ST116, ST480, ST59, ST416, ST21, ST67, ST16, ST585 and ST18. None of them carried multi-drug resistance gene cfr. Only one strain had the G2658 T mutation of target 23S rRNA gene. Thirteen (13/16, 81.3%) strains harbored the novel oxazolidinone resistance gene optrA. WGS analysis showed that the optrA gene was flanked by sequence IS1216E insertion in 13 strains, and optrA was adjacent to transposons Tn558 in two strains and Tn554 in one strain. The optrA gene was identified to be co-localized with fexA, the resistance genes mediated florfenicol resistance in 13 strains, and ermA1, the resistance genes mediated erythromycin resistance in 9 strains, indicating that linezolid-resistant strains may be selected due to non-oxazolidinone antibiotics (i.e. macrolides and florfenicol) usage. CONCLUSION: Our findings demonstrate the high diversity of optrA-carrying genetic platforms. The mobile genetic elements (MGEs) may play an important role in the dissemination of optrA into the enterococci isolates of human origin. The genetic evidence of transferable feature and co-selection of optrA should be gave more attention in clinical practice.201931299904
1350110.9878High occurrence of Enterococcus faecalis, Enterococcus faecium, and Vagococcus lutrae harbouring oxazolidinone resistance genes in raw meat-based diets for companion animals - a public health issue, Switzerland, September 2018 to May 2020. IntroductionEnterococci harbouring genes encoding resistance to florfenicol and the oxazolidinone antimicrobial linezolid have emerged among food-producing animals and meat thereof, but few studies have analysed their occurrence in raw meat-based diets (RMBDs) for pets.AimWe aimed to examine how far RMBDs may represent a source of bacteria with oxazolidinone resistance genes.MethodsFifty-nine samples of different types of RMBDs from 10 suppliers (three based in Germany, seven in Switzerland) were screened for florfenicol-resistant Gram-positive bacteria using a selective culture medium. Isolates were phenotypically and genotypically characterised.ResultsA total of 27 Enterococcus faecalis, Enterococcus faecium, and Vagococcus lutrae isolates were obtained from 24 of the 59 samples. The optrA, poxtA, and cfr genes were identified in 24/27, 6/27 and 5/27 isolates, respectively. Chloramphenicol and linezolid minimum inhibitory concentrations (MICs) ranged from 24.0 mg/L-256.0 mg/L, and 1.5 mg/L-8.0 mg/L, respectively. According to the Clinical and Laboratory Standards Institute (CLSI) breakpoints, 26 of 27 isolates were resistant to chloramphenicol (MICs ≥ 32 mg/L), and two were resistant to linezolid (MICs ≥ 8 mg/L). Multilocus sequence typing analysis of the 17 E. faecalis isolates identified 10 different sequence types (ST)s, with ST593 (n = 4 isolates) and ST207 (n = 2 isolates) occurring more than once, and two novel STs (n = 2 isolates). E. faecium isolates belonged to four different STs (168, 264, 822, and 1846).ConclusionThe high occurrence in our sample of Gram-positive bacteria harbouring genes encoding resistance to the critical antimicrobial linezolid is of concern since such bacteria may spread from companion animals to humans upon close contact between pets and their owners.202336757316
5406120.9877Detection of poxtA- and optrA-carrying E. faecium isolates in air samples of a Spanish swine farm. OBJECTIVE: Two linezolid-resistant Enterococcus faecium isolates, C10004 and C10009, were recovered from air samples of a Spanish swine farm and comprehensively characterized. METHODS: Detection of linezolid resistance mechanisms (mutations and acquisition of resistance genes) was performed by PCR/sequencing. Isolates were characterized by multilocus sequence typing (MLST), antimicrobial susceptibility testing, detection of antimicrobial resistance and virulence genes, and analysis of the genetic environment of the linezolid resistance genes. The characterization of isolate C10009 was performed by Whole-Genome-Sequencing and of isolate C10004 by PCR and amplicon sequencing, where applicable. Conjugation experiments to assess the transferability of the optrA and poxtA genes implicated in linezolid resistance were performed. RESULTS: The linezolid-resistant E. faecium isolates C10004 and C10009, assigned to ST128 and ST437, respectively, harbored the optrA and poxtA genes. Neither mutations in the 23S rRNA nor in the genes for the ribosomal proteins L3, L4 and L22 were detected. C10004 and C10009 carried fourteen and thirteen antimicrobial resistance genes, respectively. The sequence alignment indicated that the genetic environment of the poxtA gene was identical in both isolates, with a downstream-located fexB gene. The poxtA gene was transferred by conjugation together with the fexB gene, and also with tet(M) and tet(L) in the case of isolate C10004. The optrA gene could not be transferred. CONCLUSIONS: This is the first report of the poxtA gene in Spain. The presence of poxtA- and optrA-carrying E. faecium isolates in air samples represents a public health concern, indicating an involvement of swine farms in the spread of linezolid-resistant bacteria.202031884049
1250130.9877Distribution of 16S rRNA methylases among different species of Gram-negative bacilli with high-level resistance to aminoglycosides. 16S rRNA methylases confer high-level resistance to most aminoglycosides in Gram-negative bacteria. Seven 16S rRNA methylase genes, armA, rmtA, rmtB, rmtC, rmtD, rmtE and npmA, have been identified since 2003. We studied the distribution of methylase genes in more than 200 aminoglycoside-resistant Gram-negative clinical isolates collected in 2007 at our hospital in Shanghai, China. 16S rRNA methylase genes were amplified by polymerase chain reaction (PCR) among 217 consecutive clinical isolates of Gram-negative bacilli resistant to gentamicin and amikacin by a disk diffusion method. 16S rRNA methylase genes were present in 97.5% (193/198) of clinical isolates highly resistant to amikacin (≥512 μg/ml), with armA and rmtB detected in 67.2 and 30.3% of strains, respectively, while no 16S rRNA methylase genes were detected in 19 strains with amikacin minimum inhibitory concentration (MIC) ≤256 μg/ml. armA or rmtB genes were detected in 100% of 104 strains of Enterobacteriaceae, and these two genes were equally represented (49 vs. 55 strains). Genes for armA or rmtB were detected in 94.7% (89/94) of Acinetobacter baumannii and Pseudomonas aeruginosa strains, and armA was predominant (84 vs. 5 strains with rmtB). No rmtA, rmtC, rmtD or npmA genes were found. Enterobacterial repetitive intergenic consensus sequence (ERIC-PCR) indicated that armA and rmtB genes were spread by both horizontal transfer and clonal dissemination.201020614151
5420140.9877A high incidence and coexistence of multiresistance genes cfr and optrA among linezolid-resistant enterococci isolated from a teaching hospital in Wenzhou, China. Linezolid is considered as a last-resort antimicrobial agent, the resistance of which is of great concern. The aim of this study was to investigate the mechanisms and transferability of linezolid resistance and molecular epidemiology of linezolid-resistant enterococcal isolates in Wenzhou, China. A collection of 1623 enterococcal strains, including 789 Enterococcus faecalis and 834 Enterococcus faecium, were isolated from our hospital during 2011-2016. Antimicrobial susceptibility testing and clinical data analysis were performed. Molecular mechanisms of linezolid resistance, including the existence of resistance genes cfr and optrA, as well as the mutations in 23S rRNA and ribosomal proteins L3, L4, and L22, were investigated by PCR and sequencing. Conjugation experiments were conducted, and epidemiological characteristics were analyzed by PFGE and MLST. In our study, 31 (3.93%) E. faecalis and 2 (0.24%) E. faecium exhibited resistance to linezolid. Risk factors correlated with linezolid-resistant enterococcal infections included gastrointestinal surgery hospitalization, urogenital disorders, tumor, diabetes, and polymicrobial infections. Among these isolates, 6 (18.18%) harbored cfr, 9 (27.27%) harbored optrA, and 18 (54.55%) co-harbored cfr and optrA. However, mutational mechanisms were not found in this study. Conjugation experiments demonstrated the transferability of cfr and optrA between Gram-positive and Gram-negative bacteria. The clone of these isolates was diverse and scattered. It is noteworthy that cfr and optrA were the main mechanisms of linezolid resistance in this study, posing a potential risk of spread of linezolid resistance. Strikingly, it reported firstly that the two transferable resistance genes cfr and optrA coexisted in the same E. faecalis isolates.201829909468
1753150.9877Characterization of a Linezolid- and Vancomycin-Resistant Streptococcus suis Isolate That Harbors optrA and vanG Operons. Linezolid and vancomycin are among the last-resort antimicrobial agents in the treatment of multidrug-resistant Gram-positive bacterial infections. Linezolid- and vancomycin-resistant (LVR) Gram-positive bacteria may pose severe threats to public health. In this study, three optrA- and vanG-positive Streptococcus suis strains were isolated from two farms of different cities. There were only 1 and 343 single-nucleotide polymorphisms in coding region (cSNPs) of HCB4 and YSJ7 to YSJ17, respectively. Mobilome analysis revealed the presence of vanG, erm(B), tet(O/W/32/O), and aadE-apt-sat4-aphA3 cluster on an integrative and conjugative element, ICESsuYSJ17, and erm(B), aphA3, aac(6')-aph(2″), catpC(194), and optrA on a prophage, ΦSsuYSJ17-3. ICESsuYSJ17 exhibited a mosaic structure and belongs to a highly prevalent and transferable ICESa2603 family of Streptococcus species. ΦSsuYSJ17-3 shared conserved backbone to a transferable prophage Φm46.1. A novel composite transposon, IS1216E-araC-optrA-hp-catpC(194)-IS1216E, which can be circulated as translocatable unit (TU) by IS1216E, was integrated on ΦSsuYSJ17-3. Vancomycin resistance phenotype and vanG transcription assays revealed that the vanG operon was inducible. The LVR strain YSJ17 exhibited moderate virulence in a zebrafish infection model. To our knowledge, this is the first report of LVR isolate, which is mediated by acquired resistance genes optrA and vanG operons in Gram-positive bacteria. Since S. suis has been recognized as an antimicrobial resistance reservoir in the spread of resistance genes to major streptococcal pathogens, the potential risks of disseminating of optrA and vanG from S. suis to other Streptococcus spp. are worrisome and routine surveillance should be strengthened.201931551963
1752160.9876Genetic 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
1990170.9875Genomic Analysis of Aeromonas veronii C198, a Novel Mcr-3.41-Harboring Isolate from a Patient with Septicemia in Thailand. The resistance of Gram-negative bacteria to colistin, mediated by plasmid-borne mcr genes, is an emerging public health concern. The complete genome sequence (4.55 Mb) of a clinical isolate of Aeromonas veronii biovar veronii obtained from a patient with septicemia was determined using short-read and long-read platforms. This isolate (C198) was found to harbor a novel mcr-3 gene, designated mcr-3.41. Isolate C198 revealed adjacent mcr-3.41 and mcr-3-like genes. It contained one chromosome and two plasmids, both of which encoded a RepB replication protein. Other antimicrobial resistance genes, including bla(cphA3), bla(OXA-12), tetA, rsmA, and adeF, were also present. Isolate C198 was resistant to amoxicillin-clavulanate, ampicillin-sulbactam and tetracycline, and showed intermediate resistance to trimethoprim-sulfamethoxazole. The isolate was susceptible to piperacillin-tazobactam, carbapenem, third-generation cephalosporins, fluoroquinolones, chloramphenicol, and aminoglycosides. Putative virulence genes in the C198 genome encoded type II, III, and VI secretion systems; type IV Aeromonas pili; and type I fimbria, flagella, hemagglutinin, aerolysin, and hemolysins. Multilocus sequence typing revealed a novel sequence type (ST), ST720 for C198. Phylogenetic analysis of the single nucleotide polymorphisms in C198 demonstrated that the strain was closely related to A. veronii 17ISAe. The present study provides insights into the genomic characteristics of human A. veronii isolates.202033317051
1505180.9875New 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
5872190.9875Characterization 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