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541300.9863First detection of the staphylococcal trimethoprim resistance gene dfrK and the dfrK-carrying transposon Tn559 in enterococci. The trimethoprim resistance gene dfrK has been recently described in Staphylococcus aureus, but so far has not been found in other bacteria. A total of 166 enterococci of different species (E. faecium, E. faecalis, E. hirae, E. durans, E. gallinarum, and E. casseliflavus) and origins (food, clinical diseases in humans, healthy humans or animals, and sewage) were studied for their susceptibility to trimethoprim as determined by agar dilution (European Committee on Antimicrobial Susceptibility Testing) and the presence of (a) the dfrK gene and its genetic environment and (b) other dfr genes. The dfrK gene was detected in 49% of the enterococci (64% and 42% of isolates with minimum inhibitory concentrations of ≥2 mg/L or ≤1 mg/L, respectively). The tet(L)-dfrK linkage was detected in 21% of dfrK-positive enterococci. The chromosomal location of the dfrK gene was identified in one E. faecium isolate in which the dfrK was not linked to tet(L) gene but was part of a Tn559 element, which was integrated in the chromosomal radC gene. This Tn559 element was also found in 14 additional isolates. All combinations of dfr genes were detected among the isolates tested (dfrK, dfrG, dfrF, dfrK+dfrG, dfrK+dfrF, dfrF+dfrG, and dfrF+dfrG+dfrK). The gene dfrK gene was found together with other dfr genes in 58% of the tested enterococci. This study suggested an exchange of the trimethoprim resistance gene dfrK between enterococci and staphylococci, as previously observed for the trimethoprim resistance gene dfrG.201221718151
591210.9863Antibiotic Resistance-Susceptibility Profiles of Enterococcus faecalis and Streptococcus spp. From the Human Vagina, and Genome Analysis of the Genetic Basis of Intrinsic and Acquired Resistances. The spread of antibiotic resistance is a major public health concern worldwide. Commensal bacteria from the human genitourinary tract can act as reservoirs of resistance genes playing a role in their transfer to pathogens. In this study, the minimum inhibitory concentration of 16 antibiotics to 15 isolates from the human vagina, identified as Enterococcus faecalis, Streptococcus anginosus, and Streptococcus salivarius, was determined. Eight isolates were considered resistant to tetracycline, five to clindamycin and quinupristin-dalfopristin, and four to rifampicin. To investigate the presence of antimicrobial resistance genes, PCR analysis was performed in all isolates, and five were subjected to whole-genome sequencing analysis. PCR reactions identified tet(M) in all tetracycline-resistant E. faecalis isolates, while both tet(M) and tet(L) were found in tetracycline-resistant S. anginosus isolates. The tet(M) gene in E. faecalis VA02-2 was carried within an entire copy of the transposon Tn916. In S. anginosus VA01-10AN and VA01-14AN, the tet(M) and tet(L) genes were found contiguous with one another and flanked by genes encoding DNA mobilization and plasmid replication proteins. Amplification and sequencing suggested the lsaA gene to be complete in all E. faecalis isolates resistant to clindamycin and quinupristin-dalfopristin, while the gene contain mutations rendering to a non-functional LsaA in susceptible isolates. These results were subsequently confirmed by genome analysis of clindamycin and quinupristin-dalfopristin resistant and susceptible E. faecalis strains. Although a clinical breakpoint to kanamycin for S. salivarius has yet to be established, S. salivarius VA08-2AN showed an MIC to this antibiotic of 128 μg mL(-1). However, genes involved in kanamycin resistance were not identified. Under the assayed conditions, neither tet(L) nor tet(M) from either E. faecalis or S. anginosus was transferred by conjugation to recipient strains of E. faecalis, Lactococcus lactis, or Lactobacillus plantarum. Nonetheless, the tet(L) gene from S. anginosus VA01-10AN was amplified by PCR, and cloned and expressed in Escherichia coli, to which it provided a resistance of 48-64 μg mL(-1) to tetracycline. Our results expand the knowledge of the antibiotic resistance-susceptibility profiles of vaginal bacteria and provide the genetic basis of their intrinsic and acquired resistance.202032695087
357020.9861A newly discovered Bacteroides conjugative transposon, CTnGERM1, contains genes also found in gram-positive bacteria. Results of a recent study of antibiotic resistance genes in human colonic Bacteroides strains suggested that gene transfer events between members of this genus are fairly common. The identification of Bacteroides isolates that carried an erythromycin resistance gene, ermG, whose DNA sequence was 99% identical to that of an ermG gene found previously only in gram-positive bacteria raised the further possibility that conjugal elements were moving into Bacteroides species from other genera. Six of seven ermG-containing Bacteroides strains tested were able to transfer ermG by conjugation. One of these strains was chosen for further investigation. Results of pulsed-field gel electrophoresis experiments showed that the conjugal element carrying ermG in this strain is an integrated element about 75 kb in size. Thus, the element appears to be a conjugative transposon (CTn) and was designated CTnGERM1. CTnGERM1 proved to be unrelated to the predominant type of CTn found in Bacteroides isolates-CTns of the CTnERL/CTnDOT family-which sometimes carry another type of erm gene, ermF. A 19-kbp segment of DNA from CTnGERM1 was cloned and sequenced. A 10-kbp portion of this segment hybridized not only to DNA from all the ermG-containing strains but also to DNA from strains that did not carry ermG. Thus, CTnGERM1 seems to be part of a family of CTns, some of which have acquired ermG. The percentage of G+C content of the ermG region was significantly lower than that of the chromosome of Bacteroides species-an indication that CTnGERM1 may have entered Bacteroides strains from some other bacterial genus. A survey of strains isolated before 1970 and after 1990 suggests that the CTnGERM1 type of CTn entered Bacteroides species relatively recently. One of the genes located upstream of ermG encoded a protein that had 85% amino acid sequence identity with a macrolide efflux pump, MefA, from Streptococcus pyogenes. Our having found >90% sequence identity of two upstream genes, including mefA, and the remnants of two transposon-carried genes downstream of ermG with genes found previously only in gram-positive bacteria raises the possibility that gram-positive bacteria could have been the origin of CTnGERM1.200312902247
126730.9860Detection and characterization of methicillin-resistant and susceptible coagulase-negative staphylococci in milk from cows with clinical mastitis in Tunisia. OBJECTIVES: This study investigated prevalence of methicillin-resistant (MR) and methicillin-susceptible (MS) coagulase-negative staphylococci (CNS) and the implicated mechanisms of resistance and virulence in milk of mastitis cows. In addition, the presence of SCCmec type was analyzed in MR Staphylococcus epidermidis (MRSE). RESULTS: Three hundred milk samples from cows with clinical mastitis were obtained from 30 dairy farms in different regions of Tunisia. Sixty-eight of the 300 tested samples contained CNS strains. Various CNS species were identified, with Staphylococcus xylosus being the most frequently found (40%) followed by Staphylococcus warneri (12%). The mecA gene was present in 14 of 20 MR-CNS isolates. All of them were lacking the mecC gene. The SCCmecIVa was identified in four MRSE isolates. Most of CNS isolates showed penicillin resistance (70.6%) and 58.3% of them carried the blaZ gene. MR-CNS isolates (n = 20) showed resistance to erythromycin, tetracycline and trimethoprim-sulfametoxazole harboring different resistance genes such us erm(B), erm(T), erm(C), mph(C) or msr(A), tet(K) and dfr(A). However, a lower percentage of resistance was observed among 48 MS-CNS isolates: erythromycin (8.3%), tetracycline (6.2%), streptomycin (6.2%), clindamycin (6.2%), and trimethoprim-sulfametoxazole (2%). The Inu(B) gene was detected in one Staphylococcus xylosus strain that showed clindamycin resistance. The virulence gene tsst-1 was observed in one MR-CNS strain. DISCUSSION: Coagulase-negative staphylococci containing a diversity of antimicrobial resistance genes are frequently detected in milk of mastitis cows. This fact emphasizes the importance of identifying CNS when an intramammary infection is present because of the potential risk of lateral transfer of resistant genes among staphylococcal species and other pathogenic bacteria.201830077662
132240.9859Phenotypic and genotypic characterization of antimicrobial resistance in faecal enterococci from wild boars (Sus scrofa). The objective was to study the prevalence of antimicrobial resistance and the mechanisms implicated in faecal enterococci of wild boars in Portugal. One hundred and thirty-four enterococci (67 E. faecium, 54 E. hirae, 2 E. faecalis, 2 E. durans and 9 Enterococcus spp.) were recovered from 67 wild boars (two isolates/sample), and were further analysed. High percentages of resistance were detected for erythromycin, tetracycline, and ciprofloxacin (48.5%, 44.8%, and 17.9%, respectively), and lower values were observed for high-level-kanamycin, -streptomycin, chloramphenicol, and ampicillin resistance (9%, 6.7%, 4.5%, and 3.7%, respectively). No isolates showed vancomycin or high-level-gentamicin resistance. The erm(B), tet(M), aph(3')-IIIa, and ant(6)-I genes were demonstrated in all erythromycin-, tetracycline-, kanamycin-, and streptomycin-resistant isolates, respectively. Specific genes of Tn916/Tn1545 and Tn5397 transposons were detected in 78% and 47% of our tet(M)-positive enterococci, respectively. The tet(S) and tet(K) genes were detected in one isolate of E. faecium and E. hirae, respectively. Three E. faecium isolates showed quinupristin-dalfopristin resistance and the vat(E) gene was found in all of them showing the erm(B)-vat(E) linkage. Four E. faecium isolates showed ampicillin-resistance and all of them presented seven amino acid substitutions in PBP5 protein (461Q-->K, 470H-->Q, 485M-->A, 496N-->K, 499A-->T, 525E-->D, and 629E-->V), in relation with the reference one; a serine insertion at 466' position was found in three of the isolates. Faecal enterococci from wild boars harbour a variety of antimicrobial resistance mechanisms and could be a reservoir of antimicrobial resistance genes and resistant bacteria that could eventually be transmitted to other animals or even to humans.200717658226
538650.9858Antibiotic 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
541260.9858Molecular basis of resistance to macrolides and other antibiotics in commensal viridans group streptococci and Gemella spp. and transfer of resistance genes to Streptococcus pneumoniae. We assessed the mechanisms of resistance to macrolide-lincosamide-streptogramin B (MLS(B)) antibiotics and related antibiotics in erythromycin-resistant viridans group streptococci (n = 164) and Gemella spp. (n = 28). The macrolide resistance phenotype was predominant (59.38%); all isolates with this phenotype carried the mef(A) or mef(E) gene, with mef(E) being predominant (95.36%). The erm(B) gene was always detected in strains with constitutive and inducible MLS(B) resistance and was combined with the mef(A/E) gene in 47.44% of isolates. None of the isolates carried the erm(A) subclass erm(TR), erm(A), or erm(C) genes. The mel gene was detected in all but four strains carrying the mef(A/E) gene. The tet(M) gene was found in 86.90% of tetracycline-resistant isolates and was strongly associated with the presence of the erm(B) gene. The cat(pC194) gene was detected in seven chloramphenicol-resistant Streptococcus mitis isolates, and the aph(3')-III gene was detected in four viridans group streptococcal isolates with high-level kanamycin resistance. The intTn gene was found in all isolates with the erm(B), tet(M), aph(3')-III, and cat(pC194) gene. The mef(E) and mel genes were successfully transferred from both groups of bacteria to Streptococcus pneumoniae R6 by transformation. Viridans group streptococci and Gemella spp. seem to be important reservoirs of resistance genes.200415328112
545370.9858Sequence-Based Characterization of Tn5801-Like Genomic Islands in Tetracycline-Resistant Staphylococcus pseudintermedius and Other Gram-positive Bacteria from Humans and Animals. Antibiotic resistance in pathogens is often associated with mobile genetic elements, such as genomic islands (GI) including integrative and conjugative elements (ICEs). These can transfer resistance genes within and between bacteria from humans and/or animals. The aim of this study was to investigate whether Tn5801-like GIs carrying the tetracycline resistance gene, tet(M), are common in Staphylococcus pseudintermedius from pets, and to do an overall sequences-based characterization of Tn5801-like GIs detected in Gram-positive bacteria from humans and animals. A total of 27 tetracycline-resistant S. pseudintermedius isolates from Danish pets (1998-2005) were screened for tet(M) by PCR. Selected isolates (13) were screened for GI- or ICE-specific genes (int Tn5801 or xis Tn916 ) and their tet(M) gene was sequenced (Sanger-method). Long-range PCR mappings and whole-genome-sequencing (Illumina) were performed for selected S. pseudintermedius-isolates (seven and three isolates, respectively) as well as for human S. aureus isolates (seven and one isolates, respectively) and one porcine Enterococcus faecium isolate known to carry Tn5801-like GIs. All 27 S. pseudintermedius were positive for tet(M). Out of 13 selected isolates, seven contained Tn5801-like GIs and six contained Tn916-like ICEs. Two different Tn5801-like GI types were detected among S. pseudintermedius (Tn5801 and GI6287) - both showed high similarity compared to GenBank sequences from human pathogens. Two distinct Tn5801-like GI types were detected among the porcine E. faecium and human S. aureus isolates (Tn6014 and GI6288). Tn5801-like GIs were detected in GenBank-sequences from Gram-positive bacteria of human, animal or food origin worldwide. Known Tn5801-like GIs were divided into seven types. The results showed that Tn5801-like GIs appear to be relatively common in tetracycline-resistant S. pseudintermedius in Denmark. Almost identical Tn5801-like GIs were identified in different Gram-positive species of pet and human origin, suggesting that horizontal transfer of these elements has occurred between S. pseudintermedius from pets and human pathogens, including S. aureus.201627199912
299580.9858Antibiotic resistance in bacteria from magpies (Pica pica) and rabbits (Oryctolagus cuniculus) from west Wales. The prevalence of antibiotic-resistant bacteria in wild animal and bird populations is largely unknown, with little consistency among the few published reports. We therefore examined intestinal bacteria from magpies (Pica pica) and rabbits (Oryctolagus cuniculus) collected in rural west Wales. Escherichia coli isolates resistant to multiple antibiotics were grown from eight of 20 magpies trapped in spring, 1999 and one of 17 in spring, 2000; the most prevalent resistance trait among these isolates was to tetracycline, but resistances to ampicillin, chloramphenicol, kanamycin, sulphonamide, tetracycline and trimethoprim were also found. Tetracycline-resistant Enterococcus spp. were found in one of 20 magpies in 1999 and three of 17 in 2000. Only one resistant E. coli isolate was detected among gut bacteria from 13 rabbits, and this strain was resistant only to tetracycline. Differences in the prevalence of resistance between bacteria from rabbits and magpies may reflect differences in diet: rabbits graze field edges, whereas magpies are omnivorous and opportunistic. The resistance genes found in E. coli isolates from magpies mostly corresponded to those common among human isolates, but those conferring tetracycline resistance were unique.200111722546
541190.9858Detection of the aminoglycosidestreptothricin resistance gene cluster ant(6)-sat4-aph(3 ')-III in commensal viridans group streptococci. High-level aminoglycoside resistance was assessed in 190 commensal erythromycin-resistant alpha-hemolytic streptococcal strains. Of these, seven were also aminoglycoside-resistant: one Streptococcus mitis strain was resistant to high levels of kanamycin and carried the aph(3 ')-III gene, four S. mitis strains were resistant to high levels of streptomycin and lacked aminoglycoside-modifying enzymes, and two S. oralis strains that were resistant to high levels of kanamycin and streptomycin harbored both the aph(3 ')-III and the ant(6) genes. The two S. oralis strains also carried the ant(6)-sat4- aph(3 ' ')-III aminoglycoside-streptothricin resistance gene cluster, but it was not contained in a Tn5405-like structure. The presence of this resistance gene cluster in commensal streptococci suggests an exchange of resistance genes between these bacteria and enterococci or staphylococci.200717407061
5865100.9858Unusual small plasmids carrying the novel resistance genes dfrK or apmA isolated from methicillin-resistant or -susceptible staphylococci. OBJECTIVES: The aims of this study were to identify small staphylococcal plasmids that carry either the trimethoprim resistance gene dfrK or the apramycin resistance gene apmA and analyse them for their structure and organization with regard to their potential role as precursors of large multiresistance plasmids that carry these genes. METHODS: Trimethoprim- or apramycin-resistant staphylococci from the strain collections of the two participating institutions were investigated for the presence of plasmid-borne dfrK or apmA genes. The dfrK- or apmA-carrying plasmids were sequenced completely and compared with sequences deposited in the databases. RESULTS: Two small plasmids, the 4957 bp dfrK-carrying plasmid pKKS966 from porcine Staphylococcus hyicus subsp. hyicus and the 4809 bp apmA-carrying plasmid pKKS49 from porcine methicillin-resistant Staphylococcus aureus were identified. Structural analysis revealed that both plasmids had a similar organization, comprising a single resistance gene (dfrK or apmA), a plasmid replication gene (rep) and three partly overlapping genes for mobilization proteins (mobA, mobB and mobC). Comparisons showed 71%-82% amino acid identity between the Rep and Mob proteins of these two plasmids; however, distinctly lesser percentages of identity to Rep and Mob proteins of staphylococci and other bacteria deposited in the databases were detected. CONCLUSIONS: Both plasmids, pKKS966 and pKKS49, appeared not to be typical staphylococcal plasmids. The homology to larger plasmids that harbour the genes apmA and/or dfrK was limited to these resistance genes and their immediate upstream and downstream regions and thus suggested that these small plasmids were not integrated into larger plasmids.201222718530
5390110.9858Presence of erythromycin and tetracycline resistance genes in lactic acid bacteria from fermented foods of Indian origin. Lactic acid bacteria (LAB) resistant to erythromycin were isolated from different food samples on selective media. The isolates were identified as Enterococcus durans, Enterococcus faecium, Enterococcus lactis, Enterococcus casseliflavus, Lactobacillus salivarius, Lactobacillus reuteri, Lactobacillus plantarum, Lactobacillus fermentum, Pediococcus pentosaceus and Leuconostoc mesenteroides. Of the total 60 isolates, 88 % harbored the ermB gene. The efflux gene msrA was identified in E. faecium, E. durans, E. lactis, E. casseliflavus, P. pentosaceus and L. fermentum. Further analysis of the msrA gene by sequencing suggested its homology to msrC. Resistance to tetracycline due to the genes tetM, tetW, tetO, tetK and tetL, alone or in combination, were identified in Lactobacillus species. The tetracycline efflux genes tetK and tetL occurred in P. pentosaceus and Enterococcus species. Since it appeared that LAB had acquired these genes, fermented foods may be a source of antibiotic resistance.201222644346
5396120.9857Antibiotic Resistance of Coagulase-Negative Staphylococci and Lactic Acid Bacteria Isolated from Naturally Fermented Chinese Cured Beef. This study provided phenotypic and molecular analysis of the antibiotic resistance within coagulase-negative staphylococci and lactic acid bacteria isolated from naturally fermented Chinese cured beef. A total of 49 strains were isolated by selective medium and identified at the species level by 16S rRNA gene sequencing as follows: Staphylococcus carnosus (37), Lactobacillus plantarum (6), Weissella confusa (4), Lactobacillus sakei (1), and Weissella cibaria (1). All strains were typed by random amplified polymorphic DNA fingerprinting, and their antibiotic resistances profiles to 15 antibiotics were determined as the MIC by using the agar dilution method. All the tested strains were sensitive to ampicillin, and most of them were also sensitive to penicillin, gentamycin, neomycin, norfloxacin, and ciprofloxacin with low MICs. High resistance to streptomycin, vancomycin, erythromycin, roxithromycin, lincomycin, and kanamycin was widely observed, while the resistant levels to tetracycline, oxytetracycline, and chloramphenicol varied. The presence of corresponding resistance genes in resistant isolates was investigated by PCR, with the following genes detected: tet(M) gene in 9 S. carnosus strains and 1 W. confusa strain; erm(F) gene in 10 S. carnosus strains; ere(A) gene in 6 S. carnosus strains; ere(A) gene in 4 S. carnosus strains and 1 L. plantarum strain; and str(A) gene and str(B) gene in 3 S. carnosus strains. The results indicated that multiple antibiotic resistances were common in coagulase-negative staphylococci and lactic acid bacteria strains isolated from naturally fermented Chinese cured beef. Safety analysis and risk assessment should be performed for application in meat products.201830485765
5385130.9857Environmental heterogeneity of Staphylococcus species from alkaline fermented foods and associated toxins and antimicrobial resistance genetic elements. Different samples of three products including Bikalga and Soumbala from Burkina Faso (West Africa) and Ntoba Mbodi from Congo-Brazzaville (Central Africa) were evaluated. The bacteria (400) were phenotyped and genotypically characterized by Rep-PCR, PFGE, 16S rRNA and rpoB gene sequencing and spa typing. Their PFGE profiles were compared with those of 12,000 isolates in the Center for Disease Control (CDC, USA) database. They were screened for the production of enterotoxins, susceptibility to 19 antimicrobials, presence of 12 staphylococcal toxin and 38 AMR genes and the ability to transfer erythromycin and tetracycline resistance genes to Enterococcus faecalis JH2-2. Fifteen coagulase negative (CoNS) and positive (CoPS) species characterized by 25 Rep-PCR/PFGE clusters were identified: Staphylococcus arlettae, S. aureus, S. cohnii, S. epidermidis, S. gallinarum, S. haemolyticus, S. hominis, S. pasteuri, S. condimenti, S. piscifermentans, S. saprophyticus, S. sciuri, S. simulans, S. warneri and Macrococcus caseolyticus. Five species were specific to Soumbala, four to Bikalga and four to Ntoba Mbodi. Two clusters of S. gallinarum and three of S. sciuri were particular to Burkina Faso. The S. aureus isolates exhibited a spa type t355 and their PFGE profiles did not match any in the CDC database. Bacteria from the same cluster displayed similar AMR and toxin phenotypes and genotypes, whereas clusters peculiar to a product or a location generated distinct profiles. The toxin genes screened were not detected and the bacteria did not produce the staphylococcal enterotoxins A, B, C and D. AMR genes including blazA, cat501, dfr(A), dfr(G), mecA, mecA1, msr(A) and tet(K) were identified in CoNS and CoPS. Conjugation experiments produced JH2-2 isolates that acquired resistance to erythromycin and tetracycline, but no gene transfer was revealed by PCR. The investigation of the heterogeneity of Staphylococcus species from alkaline fermented foods, their relationship with clinical and environmental isolates and their safety in relation to antimicrobial resistance (AMR) and toxin production is anticipated to contribute to determining the importance of staphylococci in alkaline fermented foods, especially in relation to the safety of the consumers.201931670141
3039140.9857Distinct recent lineages of the strA- strB streptomycin-resistance genes in clinical and environmental bacteria. We report the linkage of the strA-strB streptomycin-resistance genes with Class 1 integron sequences on pSTR1, a 75-kb multiple antibiotic-resistance plasmid from Shigella flexneri. strA-strB had previously been detected only within Tn 5393, a Tn 3-family transposon, and on small nonconjugative broad-host-range plasmids such as RSF1010. The geographic range of Tn 5393 was also extended to Pseudomonas spp. isolated from apple trees in New Zealand and soil in the USA. Comparative sequence analyses indicated that strA-strB from Tn 5393 and nonconjugative plasmids constitute distinct recent lineages with strA-strB from pSTR1 intermediate between the other two. The carriage of strA-strB within an integron, a transposon, and on broad-host-range plasmids has facilitated the world-wide dissemination of this determinant among at least 21 bacterial genera.200212029529
490150.9857Mercuric resistance genes in gram-positive oral bacteria. Mercury-resistant bacteria isolated from the oral cavities of children carried one of two types of merA gene that appear to have evolved from a common ancestor. Streptococcus oralis, Streptococcus mitis and a few other species had merA genes that were very similar to merA of Bacillus cereus strain RC607. Unlike the B. cereus RC607 merA gene, however, the streptococcal merA genes were not carried on Tn5084-like transposons. Instead, comparisons with microbial genomic sequences suggest the merA gene is located on a novel type II transposon. Coagulase-negative staphylococci and Streptococcus parasanguis had identical merA genes that represent a new merA variant.200415251199
2439160.9856Differences in distribution of MLS antibiotics resistance genes in clinical isolates of staphylococci belonging to species: S. epidermidis, S. hominis, S. haemolyticus, S. simulans and S. warneri. BACKGROUND: Macrolides and lincosamides are two leading types of antibiotics commonly used in therapies. The study examines the differences in resistance to these antibiotics and their molecular bases in S. epidermidis as well as in rarely isolated species of coagulase-negative staphylococci such as S. hominis, S. haemolyticus, S. warneri and S. simulans. The isolates were tested for the presence of the erm(A), erm(B), erm(C), lnu(A), msr(A), msr(B), mph(C), ere(A) and ere(B) genes. Phenotypic resistance to methicillin and mecA presence were also determined. RESULTS: The MLS(B) resistance mechanism was phenotypically found in isolates of species included in the study. The most prevalent MLS(B) resistance mechanism was observed in S. hominis, S. haemolyticus and S. epidermidis isolates mainly of the MLS(B) resistance constitutive type. Macrolide, lincosamide and streptogramin B resistance genes were rarely detected in isolates individually. The erm(B), ere(A) and ere(B) genes were not found in any of the strains. The erm(A) gene was determined only in four strains of S. epidermidis and S. hominis while lnu(A) was seen in eight strains (mainly in S. hominis). The erm(C) gene was present in most of S. epidermidis strains and predominant in S. hominis and S. simulans isolates. The examined species clearly differed between one another in the repertoire of accumulated genes. CONCLUSIONS: The presence of genes encoding the MLS(B) resistance among CoNS strains demonstrates these genes' widespread prevalence and accumulation in opportunistic pathogens that might become gene reservoir for bacteria with superior pathogenic potential.201931182020
5409170.9856Presence 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
5399180.9856Characterisation and transferability of antibiotic resistance genes from lactic acid bacteria isolated from Irish pork and beef abattoirs. Lactic acid bacteria isolated from Irish pork and beef abattoirs were analysed for their susceptibility to antimicrobials. Thirty-seven isolates (12 enterococci, 10 lactobacilli, 8 streptococci, 3 lactococci, 2 Leuconostoc, and 2 pediococci) were examined for phenotypic resistance using the E-test and their minimum inhibitory concentration to a panel of six antibiotics (ampicillin, chloramphenicol, erythromycin, streptomycin, tetracycline, and vancomycin) was recorded. The corresponding genetic determinants responsible were characterised by PCR. Also, the transferability of these resistance markers was assessed in filter mating assays. Of the 37 isolates, 33 were found to be resistant to one or more antibiotics. All strains were susceptible to ampicillin and chloramphenicol. The erm(B) and msrA/B genes were detected among the 11 erythromycin-resistant strains of enterococci, lactobacilli, and streptococci. Two tetracycline-resistant strains, Lactobacillus plantarum and Leuconostoc mesenteroides spp., contained tet(M) and tet(S) genes respectively. Intrinsic streptomycin resistance was observed in lactobacilli, streptococci, lactococci and Leuconostoc species; none of the common genetic determinants (strA, strB, aadA, aadE) were identified. Four of 10 strains of Enterococcus faecium were resistant to vancomycin; however, no corresponding genetic determinants for this phenotype were identified. Enterococcus faecalis strains were susceptible to vancomycin. L. plantarum, L. mesenteroides and Pediococcus pentosaceus were intrinsically resistant to vancomycin. Transfer of antibiotic resistance determinants was demonstrated in one strain, wherein the tet(M) gene of L. plantarum (23) isolated from a pork abattoir was transferred to Lactococcus lactis BU-2-60 and to E. faecalis JH2-2. This study identified the presence of antibiotic resistance markers in Irish meat isolates and, in one example, resistance was conjugally transferred to other LAB strains.201020074643
5394190.9856Antibiotic susceptibility of bacteria isolated from pasteurized milk and characterization of macrolide-lincosamide-streptogramin resistance genes. The presence of antibiotic-resistant bacteria in pasteurized milk was detected by plating 18 milk samples on selective media containing beta-lactams, macrolides, or a glycopeptide. Most samples contained gram-positive bacteria that grew on agar plates containing oxacillin, erythromycin, and/or spiramycin. The disk-diffusion method confirmed resistance to erythromycin and/or spiramycin in 86 and 65% of the coryneform bacteria and Micrococcaceae tested, respectively. PCR and sequence analysis revealed the presence of an ermC gene in 2 of the 25 Micrococcaceae strains investigated for their resistance to erythromycin and/or spiramycin. None of the 14 corynebacteria strains resistant to erythromycin and/or spiramycin harbored the erm(X) gene. No gene transfer could be demonstrated between the two erm(C) staphylococcal isolates and recipient strains of Enterococcus faecalis JH2-2 or Staphylococcus aureus 80CR5.200515726980