PLSA - Word Related Documents




#
Rank
Similarity
Title + Abs.
Year
PMID
012345
540900.9104Presence and new genetic environment of pleuromutilin-lincosamide-streptogramin A resistance gene lsa(E) in Erysipelothrix rhusiopathiae of swine origin. Erysipelothrix rhusiopathiae is a Gram-positive bacillus that causes erysipelas in swine. In recent years, erysipelas infection among swine in China has been increasing. A combined resistance phenotype to pleuromutilins, lincosamides, and streptogramin A (PLSA phenotype) was found in some E. rhusiopathiae isolates. The aim of this study was to identify the resistance genes responsible for the PLSA phenotype in E. rhusiopathiae strains and to map the genetic environment of the identified resistance gene. A total of 46 E. rhusiopathiae isolates from 31 pig farms in China were studied. Minimum inhibitory concentrations (MICs) of 11 antimicrobial agents were determined by broth microdilution method. Seven were highly resistant to tiamulin (MICs 32 μg/ml) and clindamycin (MICs 64 μg/ml). Resistance genes responsible for the PLSA phenotype were screened by PCR. The lsa(E), spw, lnu(B), aadE and aphA3 genes were detected in strains had the PLSA phenotype, whereas none was detected in susceptible strains. The genetic environment of lsa(E) gene was determined by whole-genome sequencing and overlapping PCR assays. A novel multiresistance gene cluster, orf1-aadE-apt-spw-lsa(E)-lnu(B)-rec-orf2-orf1-aadE-sat4-aphA3, was found. Horizontal gene transfer experiments and whole-genome sequencing suggested that the lsa(E)-carrying multiresistance gene cluster was located in the chromosome. This is the first molecular characterization of PLSA resistance in E. rhusiopathiae. The lsa(E), spw and lnu(B) genes were found in E. rhusiopathiae for the first time. A novel lsa(E)-carrying multiresistance gene cluster was found. The location of lsa(E) in different gene cluster facilitates its persistence and dissemination.201525759293
522110.9054Molecular cloning of the DNA gyrase genes from Methylovorus sp. strain SS1 and the mechanism of intrinsic quinolone resistance in methylotrophic bacteria. The genes encoding the DNA gyrase A (GyrA) and B subunits (GyrB) of Methylovorus sp. strain SS1 were cloned and sequenced. gyrA and gyrB coded for proteins of 846 and 799 amino acids with calculated molecular weights of 94,328 and 88,714, respectively, and complemented Escherichia coli gyrA and gyrB temperature sensitive (ts) mutants. To analyze the role of type II topoisomerases in the intrinsic quinolone resistance of methylotrophic bacteria, the sequences of the quinolone resistance-determining regions (QRDRs) in the A subunit of DNA gyrase and the C subunit (ParC) of topoisomerase IV (Topo IV) of Methylovorus sp. strain SS1, Methylobacterium extorquens AM1 NCIB 9133, Methylobacillus sp, strain SK1 DSM 8269, and Methylophilus methylotrophus NCIB 10515 were determined. The deduced amino acid sequences of the QRDRs of the ParCs in the four methylotrophic bacteria were identical to that of E. coli ParC. The sequences of the QRDR in GyrA were also identical to those in E. coli GyrA except for the amino acids at positions 83, 87, or 95. The Ser83 to Thr substitution in Methylovorus sp. strain SS1, and the Ser83 to Leu and Asp87 to Asn substitutions in the three other methylotrophs, agreed well with the minimal inhibitory concentrations of quinolones in the four bacteria, suggesting that these residues play a role in the intrinsic susceptibility of methylotrophic bacteria to quinolones.200516404155
175220.9046Genetic 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
537730.9040Synthetic lincosamides iboxamycin and cresomycin are active against ocular multidrug-resistant methicillin-resistant Staphylococcus aureus carrying erm genes. OBJECTIVE: Antimicrobial resistance is a global pandemic that poses a major threat to vision health as ocular bacteria, especially methicillin-resistant Staphylococcus aureus (MRSA), are becoming increasingly resistant to first-line therapies. Here we evaluated the antimicrobial activity of new synthetic lincosamides in comparison to currently used antibiotics against clinical ocular MRSA isolates. METHODS: Antimicrobial susceptibility testing was performed by broth microdilution for two novel synthetic lincosamides (iboxamycin and cresomycin) and eight comparator antibiotics against a collection of 50 genomically characterised ocular MRSA isolates, including isolates harbouring erm genes (n = 25). RESULTS: Both drugs were active against widespread MRSA clonal complexes CC8 and CC5. The MIC(50) and MIC(90) of iboxamycin were 0.06 and 2 mg/L, respectively. Cresomycin (MIC(50) = 0.06 mg/L) also displayed good activity with an in vitro potency four-fold higher (MIC(90) = 0.5 mg/L) than iboxamycin. In isolates harbouring erm genes, MIC(90) were >16, 2, and 0.5 mg/L for clindamycin, iboxamycin, and cresomycin, respectively. The in vitro potencies of iboxamycin and cresomycin were similar or higher than that of comparator agents and were not impacted by multidrug-resistance phenotypes or by the presence of erm genes when compared with clindamycin. CONCLUSIONS: Our results demonstrate that iboxamycin and cresomycin display potent in vitro activity against ocular MRSA isolates, including multidrug-resistant isolates harbouring erm genes.202439293511
124740.9039Antibiotic resistance determinants of multidrug-resistant Acinetobacter baumannii clinical isolates in Algeria. Antibiotic susceptibility testing was performed on 71 Acinetobacter baumannii clinical isolates, and presence of antibiotic resistance genes was screened for by PCR amplification and sequencing. Resistance rates were very high for aminoglycosides (22-80%), fluoroquinolones (>90%), and cephalosporins (>90%) but remained low for rifampin (2.8%) or null for colistin. Antibiotic resistance encoding genes detected were as follows: blaTEM-128 gene (74.6%), aph(3')-VI (50.7 %), aadA (63.4%), ant(2″)-I (14.1%), aac(3)-Ia (91.1%), aac(6')-Ib (4.2%), mutation Ser83Leu in gyrA (94.4%), double mutations Ser83Leu and Ser80Leu (or Ser84Leu) in gyrA and parC (69.0%), and mutation I581N in RRDR of the rpoB gene.201323688522
126050.9038Isolation, Identification, and Antimicrobial Susceptibilities of Bacteria from the Conjunctival Sacs of Dogs with Bacterial Conjunctivitis in Different Regions of Wuhan, China. In order to investigate the bacterial species present in the conjunctival sacs of dogs with bacterial conjunctivitis in Wuhan (Hongshan District, Wuchang District, Jiangxia District, and Huangpi District) and their resistance to aminoglycoside antibiotics, samples of conjunctival sac secretions were collected from 56 dogs with bacterial conjunctivitis in various regions of Wuhan. Drug susceptibility testing for aminoglycoside antibiotics was performed on the most commonly isolated gram-positive and gram-negative bacteria. The expression of two aminoglycoside modifying enzyme genes, aacA-aphD and aac (6')-Ib, and three 16S rRNA methyltransferase genes, rmtB, rmtE and npmA, were analyzed by PCR. The results showed that a total of 123 bacterial strains were cultured from 56 conjunctival sac secretion samples, with Staphylococcus being the most commonly isolated species, followed by Escherichia. Among them, 14 strains of Staphylococcus pseudointermedius were not resistant to tobramycin, amikacin, gentamicin or neomycin, but the resistance rates to streptomycin and kanamycin were 35.71% and 42.86%, respectively. Among them, 14 Escherichia coli strains were not resistant to tobramycin and gentamicin, but they showed high resistance rates to neomycin and kanamycin (both at 50%). The detection rate of the aacA-aphD gene in Staphylococcus pseudointermedius strains was 100%. The detection rates of the rmtB gene and rmtE gene in Escherichia coli were 85.71% and 28.57%, respectively, while the aac(6')-Ib gene and npmA gene were not detected.202539852896
538760.9038Assessment of antibiotic susceptibility within lactic acid bacteria strains isolated from wine. Susceptibility to 12 antibiotics was tested in 75 unrelated lactic acid bacteria strains of wine origin of the following species: 38 Lactobacillus plantarum, 3 Lactobacillus hilgardii, 2 Lactobacillus paracasei, 1 Lactobacillus sp, 21 Oenococcus oeni, 4 Pediococcus pentosaceus, 2 Pediococcus parvulus, 1 Pediococcus acidilactici, and 3 Leuconostoc mesenteroides. The Minimal Inhibitory Concentrations of the different antibiotics that inhibited 50% of the strains of the Lactobacillus, Leuconostoc and Pediococcus genera were, respectively, the following ones: penicillin (2, < or =0.5, and < or =0.5 microg/ml), erythromycin (< or =0.5 microg/ml), chloramphenicol (4 microg/ml), ciprofloxacin (64, 8, and 128 microg/ml), vancomycin (> or =128 microg/ml), tetracycline (8, 2, and 8 microg/ml), streptomycin (256, 32, and 512 microg/ml), gentamicin (64, 4, and 128 microg/ml), kanamycin (256, 64, and 512 microg/ml), sulfamethoxazole (> or =1024 microg/ml), and trimethoprim (16 microg/ml). All 21 O. oeni showed susceptibility to erythromycin, tetracycline, rifampicin and chloramphenicol, and exhibited resistance to aminoglycosides, vancomycin, sulfamethoxazole and trimethoprim, that could represent intrinsic resistance. Differences were observed among the O. oeni strains with respect to penicillin or ciprofloxacin susceptibility. Antibiotic resistance genes were studied by PCR and sequencing, and the following genes were detected: erm(B) (one P. acidilactici), tet(M) (one L. plantarum), tet(L) (one P. parvulus), aac(6')-aph(2") (four L. plantarum, one P. parvulus, one P. pentosaceus and two O. oeni), ant(6) (one L. plantarum, and two P. parvulus), and aph(3')-IIIa (one L. plantarum and one O. oeni). This is the first time, to our knowledge, that ant(6), aph(3')-IIIa and tet(L) genes are found in Lactobacillus and Pediococcus strains and antimicrobial resistance genes are reported in O. oeni strains.200616876896
522270.9034Resistance to macrolides by ribosomal mutation in clinical isolates of Turicella otitidis. The genetic basis of erythromycin resistance in Turicella otitidis, a coryneform bacteria associated with otitis, was studied in five macrolide-resistant clinical isolates. Macrolide resistance genes were searched for by polymerase chain reaction (PCR). Genes for domain V of 23S rRNA (rrl) as well as rplD (L4 protein) and rplV (L22 protein) genes were characterised, amplified by PCR from total genomic DNA and sequenced. In the resistant isolates, cross-resistance to macrolides and clindamycin was associated with mutations at positions 2058 and/or 2059 (Escherichia coli numbering). Three isolates displayed A2058 mutations, one isolate had an A2059G mutation whereas another one contained mutations at positions 2058 and 2059. Southern blot experiments revealed that T. otitidis had three copies of the rrl gene. In conclusion, resistance to macrolides in T. otitidis is due, at least in part, to mutations in the rrl gene.200919414240
209180.9034Antibiotic resistance and virulence profile of Klebsiella pneumoniae isolated from wild Sumatran Orangutans (Pongo abelii). OBJECTIVE: Orangutans (Pongo abelii), as endemic primates of Indonesia, are characterized by a predominantly arboreal lifestyle. Klebsiella pneumoniae (K. pneumonia) and other Gram-negative bacteria are present in the Indigenous flora of many mammals, including orangutans. This study aimed to investigate the antibiotic resistance and virulence profile of K. pneumonia isolated from wild Sumatran orangutans. MATERIALS AND METHODS: This study investigated 10 fecal samples from wild Sumatran orangutans from the Gunung Leuser National Park, Aceh, Indonesia. Biochemical and molecular identification of K. pneumoniae using the RNA polymerase subunit b gene and detection of virulence-associated genes. In addition, molecular detection of antibiotic resistance genes was performed to characterize the resistance mechanisms in the isolates. RESULTS: K. pneumonia was detected in 6 out of 10 fecal samples from wild Sumatran orangutans. The virulence genes mrkD and entB were detected in all (100%) of the isolates, whereas wabG was identified in 83.33% of the strains. Antibiotic susceptibility testing against K. pneumoniae revealed that three isolates were susceptible to streptomycin (S) and nalidixic acid (NA), while all six isolates were susceptible to chloramphenicol and ciprofloxacin. One isolate demonstrated intermediate resistance to NA, while the remaining two exhibited intermediate resistance to S. Six isolates were resistant to ampicillin, tetracycline, and erythromycin, indicating multidrug resistance. Furthermore, antibiotic resistance genes were detected in the isolates with the following prevalence: bla (TEM) gene (six isolates; 100%), bla (SHV) (six isolates; 100%), bla (CTX-M) gene (four isolates; 66.67%), and tetA gene (four isolates; 66.67%). CONCLUSION: This study revealed the virulence and resistance profile of K. pneumoniae bacterium isolated from wild Sumatran orangutans, which is essential for formulating effective conservation and healthcare strategies.202440013287
126490.9026Characterization of mannitol-fermenting methicillin-resistant staphylococci isolated from pigs in Nigeria. This study was conducted to determine the species distribution, antimicrobial resistance pheno- and genotypes and virulence traits of mannitol-positive methicillin-resistant staphylococci (MRS) isolated from pigs in Nsukka agricultural zone, Nigeria. Twenty mannitol-positive methicillin-resistant coagulase-negative staphylococcal (MRCoNS) strains harboring the mecA gene were detected among the 64 Staphylococcus isolates from 291 pigs. A total of 4 species were identified among the MRCoNS isolates, namely, Staphylococcus sciuri (10 strains), Staphylococcus lentus (6 strains), Staphylococcus cohnii (3 strains) and Staphylococcus haemolyticus (one strain). All MRCoNS isolates were multidrug-resistant. In addition to β-lactams, the strains were resistant to fusidic acid (85%), tetracycline (75%), streptomycin (65%), ciprofloxacin (65%), and trimethoprim/sulphamethoxazole (60%). In addition to the mecA and blaZ genes, other antimicrobial resistance genes detected were tet(K), tet(M), tet(L), erm(B), erm(C), aacA-aphD, aphA3, str, dfrK, dfrG, cat pC221, and cat pC223. Thirteen isolates were found to be ciprofloxacin-resistant, and all harbored a Ser84Leu mutation within the QRDR of the GyrA protein, with 3 isolates showing 2 extra substitutions, Ser98Ile and Arg100Lys (one strain) and Glu88Asp and Asp96Thr (2 strains). A phylogenetic tree of the QRDR nucleotide sequences in the gyrA gene revealed a high nucleotide diversity, with several major clusters not associated with the bacterial species. Our study highlights the possibility of transfer of mecA and other antimicrobial resistance genes from MRCoNS to pathogenic bacteria, which is a serious public health and veterinary concern.201526413075
5408100.9025Identification 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
2092110.9025Antibacterial activities of multi drug resistant Myroides odoratimimus bacteria isolated from adult flesh flies (Diptera: sarcophagidae) are independent of metallo beta-lactamase gene. Sarcophagidae) are well known cause of myiasis and their gut bacteria have never been studied for antimicrobial activity against bacteria. Antimicrobial studies of Myroides spp. are restricted to nosocomial strains. A Gram-negative bacterium, Myroides sp., was isolated from the gut of adult flesh flies (Sarcophaga sp.) and submitted to evaluation of nutritional parameters using Biolog GN, 16S rRNA gene sequencing, susceptibility to various antimicrobials by disc diffusion method and detection of metallo β-lactamase genes (TUS/MUS). The antagonistic effects were tested on Gram-negative and Gram-positive bacteria isolated from human clinical specimens, environmental samples and insect mid gut. Bacterial species included were Aeromonas hydrophila, A. culicicola, Morganella morganii subsp. sibonii, Ochrobactrum anthropi, Weissella confusa, Escherichia coli, Ochrobactrum sp., Serratia sp., Kestersia sp., Ignatzschineria sp., Bacillus sp. The Myroides sp. strain was resistant to penicillin-G, erythromycin, streptomycin, amikacin, kanamycin, gentamycin, ampicillin, trimethoprim and tobramycin. These strain showed antibacterial action against all bacterial strains except W. confusa, Ignatzschineria sp., A. hydrophila and M. morganii subsp. sibonii. The multidrug resistance of the strain was similar to the resistance of clinical isolates, inhibiting growth of bacteria from clinical, environmental and insect gut samples. The metallo β-lactamase (TUS/MUS) genes were absent, and resistance due to these genes was ruled out, indicating involvement of other secretion machinery.200824031236
5407120.9022Resistance 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
1250130.9022Distribution 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
2453140.9022Prevalence and molecular determinants of colistin resistance among commensal Enterobacteriaceae isolated from poultry in northwest of Iran. BACKGROUND: The emergence of colistin-resistant Enterobacteriaceae from human and animal sources is a public health concern as this antibiotic is considered to be the last line therapeutic option for infections caused by multidrug-resistant Gram-negative bacteria. Here we aimed to determine the prevalence of colistin resistance, among enterobacteria isolated from poultry and the possible underlying colistin resistance mechanisms. METHODS: A collection of 944 cloacal samples were obtained from poultry and screened for colistin resistance. To uncover the molecular mechanism behind colistin resistance, the presence of plasmid encoded colistin resistance genes mcr-1, mcr-2, mcr-3 and mcr-4 was examined by PCR. The nucleotide sequences of the mgrB, pmrA, pmrB, phoP, phoQ, crrA and crrB genes were determined. The genetic relatedness of the colistin resistant (ColR) isolates was evaluated by Multilocus sequence typing. Three ColR mutants were generated in vitro by repetitive drug exposure. RESULTS: Overall from 931 enteric bacteria isolated from poultry samples obtained from 131 farms, nine ColR bacteria (0.96%) with high level colistin resistance (MICs ≥ 64 mg/L) were detected all being identified as K. pneumoniae. The 9 ColR bacteria originated from different farms and belonged to 7 distinct Sequence types including ST11 (22.2%) and ST726 (22.2%) being the most prevalent STs followed by ST37, ST74, ST485, ST525 and novel sequence type 3380 (11.1% each). mcr-type genes were not detected in any isolate. In 88.8% of the isolates (n = 8), MgrB was inactivated by Insertion of IS elements (IS1-like, IS3-like, IS5-like families, positions + 75, + 113, + 117, + 135) and nonsense mutations at codons 8, 16, 30. All ColR isolates harboured wild type PmrA, PhoP, PhoQ or polymorphic variants of PmrB. Sequence analysis of the CrrB revealed a familiar S195N and 4 novel I27V, T150R, F303S and K325R substitutions. PmrB T93N substitution and mgrB locus deletion were identified in two laboratory induced ColR mutants and one mutant lacked alteration in the studied loci. In one ColR isolate with wild type MgrB an A83V substitution was detected in CrrA. CONCLUSION: It is concluded from our results that colistin resistance in the studied avian K. pneumoniae isolates was mostly linked to alterations identified within the mgrB gene.201930728861
1245150.9019Mutation-based fluoroquinolone resistance in carbapenem-resistant Acinetobacter baumannii and Escherichia coli isolates causing catheter-related bloodstream infections. OBJECTIVE: We studied the presence of mutations in the chromosomal quinolone resistance-determining regions (QRDRs) of the fluoroquinolone targets gyrA and parC genes and detected the carbapenem resistance (CR) encoding genes among Acinetobacter baumannii and Escherichia coli isolates from catheter-related bloodstream infections (CRBSIs). METHODS: The study included 39 non-duplicate isolates of A. baumannii (14/39, 35.9%) and E. coli (25/39, 64.1%) isolated from 128 confirmed CRBSIs cases. Antimicrobial susceptibility testing was performed, followed by an evaluation of biofilm formation using the tissue culture plate method. The carbapenemase encoding genes were detected by multiplex polymerase chain reaction (PCR). The mutations in QRDRs of gyrA and parC genes were determined by singleplex PCR amplification followed by DNA sequencing and BlastN analysis in the GenBank database. DNA and the translated amino acid sequences were analyzed using the Mega7 bioinformatics tool. RESULTS: Multidrug-resistant (MDR) E. coli and A. baumannii isolates harbored CR encoding genes and combined gyrA and parC genes mutation. The specific substitutions observed in GyrA were Cys173Arg, Cys174Gly, Asp80Val, Tyr178ASP, Tyr84Gly, Glu85Lys, Ser172Leu, and Asp176Asn, while the specific substitutions observed in the ParC amino acid sequence were point mutation 62 Arg, Phe60Leu, Ils66Val, and Gln76Lys. Point mutation 62Arg was detected in two A. baumannii isolates, whereas Ser172Leu mutation was observed in two E. coli isolates. CONCLUSION: The presence of new single and multiple mutations in QRDR causes the emergence of MDR E. coli and A. baumannii infections in carbapenem-resistant Enterobacteriaceae in Egypt, requiring further investigation in Gram-negative bacteria.202337151743
5386160.9015Antibiotic resistance of lactic acid bacteria isolated from Chinese yogurts. The aim of this study was to evaluate the susceptibility of 43 strains of lactic acid bacteria, isolated from Chinese yogurts made in different geographical areas, to 11 antibiotics (ampicillin, penicillin G, roxithromycin, chloramphenicol, tetracycline, chlortetracycline, lincomycin, kanamycin, streptomycin, neomycin, and gentamycin). The 43 isolates (18 Lactobacillus bulgaricus and 25 Streptococcus thermophilus) were identified at species level and were typed by random amplified polymorphic DNA analysis. Thirty-five genotypically different strains were detected and their antimicrobial resistance to 11 antibiotics was determined using the agar dilution method. Widespread resistance to ampicillin, chloramphenicol, chlortetracycline, tetracyclines, lincomycin, streptomycin, neomycin, and gentamycin was found among the 35 strains tested. All of the Strep. thermophilus strains tested were susceptible to penicillin G and roxithromycin, whereas 23.5 and 64.7% of Lb. bulgaricus strains, respectively, were resistant. All of the Strep. thermophilus and Lb. bulgaricus strains were found to be resistant to kanamycin. The presence of the corresponding resistance genes in the resistant isolates was investigated through PCR, with the following genes detected: tet(M) in 1 Lb. bulgaricus and 2 Strep. thermophilus isolates, ant(6) in 2 Lb. bulgaricus and 2 Strep. thermophilus isolates, and aph(3')-IIIa in 5 Lb. bulgaricus and 2 Strep. thermophilus isolates. The main threat associated with these bacteria is that they may transfer resistance genes to pathogenic bacteria, which has been a major cause of concern to human and animal health. To our knowledge, the aph(3')-IIIa and ant(6) genes were found in Lb. bulgaricus and Strep. thermophilus for the first time. Further investigations are required to analyze whether the genes identified in Lb. bulgaricus and Strep. thermophilus isolates might be horizontally transferred to other species.201222916881
5393170.9014Characterization and Transferability of erm and tet Antibiotic Resistance Genes in Lactobacillus spp. Isolated from Traditional Fermented Milk. Lactobacillus is a widely used bacteria and consumed through various fermented foods and beverages. Strains have been shown to carry resistance genes and mobile genetic elements with their ability to transfer the resistance to sensitive pathogenic strains. To study this, 4 cultures of Lactobacillus were isolated from traditional fermented milk. The isolates were able to grow up to 4% (w/v) NaCl concentration and 45 °C temperature, and showed > 97% 16S rRNA gene similarities with Lactobacillus fermentum. All the isolates were phenotypically screened for the presence of antibiotic resistance. Minimum inhibitory concentration (MIC) as microbiological breakpoints were observed against a varied class of antibiotics. Isolates AKO 94.6, DVM 95.7, and NIFTEM 95.8 were explicitly resistant to ampicillin, ciprofloxacin and vancomycin with MIC well beyond the maximum range of 256 µg/ml in the E-strip test. While isolate SKL1 was sensitive to ampicillin and showed MIC at 0.25 µg/ml but resistant to streptomycin and trimethoprim (MIC > 256 µg/ml). Molecular characterization showed the presence of tet(M) gene in three isolates SKL1, DVM 95.7, and NIFTEM 95.8 which was chromosomally associated resistance determinants while erm(B) resistance gene was detected in isolates DVM 95.7 and NIFTEM 95.8 only which was a plasmid associated gene and could be transferrable conjugally. Gene for Tn916 family (xis) was also observed in isolates DVM 95.7 and NIFTEM 95.8. Transferability of antibiotic resistance to pathogenic recipient strains was examined in isolates DVM 95.7 and NIFTEM 95.8 in different food matrices. The highest conjugation frequency with ~ 10(-1) was obtained in alfalfa seed sprouts. This study reports the presence of acquired gene resistance in Lactobacillus species and dissemination to susceptible strains of bacteria in different food matrices. 16S rRNA gene sequences of isolates were uploaded to the NCBI GenBank database to retrieve the accession number.202236209320
1492180.9013Characterization 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
5229190.9013Paradoxical High-Level Spiramycin Resistance and Erythromycin Susceptibility due to 23S rRNA Mutation in Streptococcus constellatus. Objectives: The aim of the study was to characterize phenotypically and genotypically an uncommon mechanism of resistance to macrolides, lincosamides, and streptogramins (MLS) in a Streptococcus milleri group clinical isolate. Materials and Methods: The isolate UCN96 was recovered from an osteoradionecrosis wound, and was identified using the matrix assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry and the partial sequencing of the sodA gene. Antimicrobial susceptibility testing were carried out by the disk diffusion method and minimal inhibitory concentrations (MICs) were determined by the broth microdilution technique. PCR screening was performed for MLS resistance genes described in Gram-positive bacteria. Specific mutations in the ribosomal proteins L3-, L4-, and L22-encoding genes were also screened and those in domain V of the 23S rRNA gene (rrl). The number of mutated copies of the rrl gene was determined using amplification-refractory mutation system quantitative-polymerase chain reaction (qPCR) analysis. Results: The clinical isolate UCN96 was unambiguously identified as Streptococcus constellatus. It was susceptible to all macrolides and lincosamides (ML) antibiotics except spiramycin (MIC >256 mg/L) while it was also resistant to streptogramins. Screening for all acquired resistance genes was negative and no mutation was found in genes coding for L3, L4, and L22 ribosomal proteins. Of interest, a single mutation, A2062C (according to Escherichia coli numbering), was detected in the domain V of 23S rRNA. Conclusion: Mutations at the position 2062 of 23S rRNA have been detected once in Streptococcus pneumoniae, and not yet in other Streptococcus spp. This mechanism is very likely uncommon in Gram-positive bacteria because different copies of 23S rRNA operons should be mutated for development of such a resistance pattern.202032031922