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233800.9929Characterization of disinfectant susceptibility profiles among clinical isolates of Acinetobacter baumannii in Ardabil, Iran. Antimicrobial disinfectants have been extensively used to control hospital-acquired infections worldwide. Prolonged exposure to bacteria could promote resistance to antimicrobial disinfectants. This study evaluated the antimicrobial activity of four commonly used disinfectants; triclosan, chlorhexidine digluconate, benzalkonium chloride, and formaldehyde against Acinetobacter baumannii clinical isolates. This study also determined the prevalence and association of efflux pumps encoding genes qacE, qacED1, emrA, and aceI with tolerance to disinfectants. A total of 100 A. baumannii isolates were included in the current study. The antimicrobial disinfectants' minimum inhibitory concentration (MIC) was determined using an agar dilution method. Genes involved in resistance to disinfectants were investigated by PCR method. The benzalkonium chloride MICs ranged between 32 and 128 μg mL-1, chlorhexidine digluconate 8-64 μg mL-1, triclosan 1-32 μg mL-1, and formaldehyde 128 μg mL-1. Overall, the highest MIC90 value was identified for formaldehyde (128 μg mL-1), followed by benzalkonium chloride and chlorhexidine digluconate (64 μg mL-1, each one) and triclosan (4 μg mL-1). In the present study, the qacE, qacED1, emrA, and aceI genes were found in 91%, 55%, 100%, and 88% of isolates, respectively. The qacG gene was not identified in our A. baumannii isolates. The qacED1 gene was associated with higher MICs for all disinfectants tested (P < 0.05), while the qacE and aceI genes were associated with higher MICs for benzalkonium chloride and chlorhexidine. This study indicated that triclosan is the most effective disinfectant against A. baumannii isolates.202338063878
538710.9924Assessment 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
125120.9922Biofilm Formation and Plasmid-Mediated Quinolone Resistance Genes at Varying Quinolone Inhibitory Concentrations in Quinolone-Resistant Bacteria Superinfecting COVID-19 Inpatients. The likelihood of antimicrobial failure in COVID-19 patients with bacterial superinfection arises from both phenotypic (biofilms) and genotypic mechanisms. This cross-sectional study aimed to determine the inhibitory concentrations of quinolones-nalidixic acid, norfloxacin, ciprofloxacin, ofloxacin, and levofloxacin-in biofilm formers (minimum biofilm inhibitory concentration [MBIC]) and nonformers (minimum inhibitory concentration [MIC]) and correlate inhibitory concentrations with plasmid-mediated quinolone resistance (PMQR) genes in quinolone-resistant bacteria isolated from COVID-19 inpatients. Quinolone-resistant bacteria (n = 193), verified through disc diffusion, were tested for quinolone inhibitory concentrations using broth microdilution and biofilm formation using microtiter plate methods. The polymerase chain reaction was used to detect PMQR genes. Study variables were analyzed using SPSS v.17.0, with a significance level set at P <0.05. MIC-to-MBIC median fold increases for ciprofloxacin, ofloxacin, and levofloxacin were 128 (2-8,192), 64 (4-1,024), and 32 (4-512) in gram-positive cocci (GPC, n = 43), respectively, whereas they were 32 (4-8,192), 32 (4-2,048), and 16 (2-1,024) in fermentative gram-negative bacilli (F-GNB, n = 126) and 16 (4-4,096), 64 (2-64), and 16 (8-512) in nonfermentative gram-negative bacilli (NF-GNB, n = 24). In biofilm-forming F-GNB and NF-GNB, qnrB (10/32 versus 3/10), aac(6')-Ib-cr (10/32 versus 4/10), and qnrS (9/32 versus 0/10) genes were detected. A 32-fold median increase in the MIC-to-MBIC of ciprofloxacin was significantly (P <0.05) associated with qnrA in F-GNB and qnrS in NF-GNB. Biofilms formed by F-GNB and NF-GNB were significantly associated with the aac(6')-Ib-cr and qnrS genes, respectively. Nearly one-third of the superinfecting bacteria in COVID-19 patients formed biofilms and had at least one PMQR gene, thus increasing the need for quinolones at higher inhibitory concentrations.202539561392
537730.9922Synthetic 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
126440.9921Characterization 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
233750.9921Klebsiella pneumoniae susceptibility to biocides and its association with cepA, qacΔE and qacE efflux pump genes and antibiotic resistance. BACKGROUND: Although antiseptics are some of the most widely used antibacterials in hospitals, there is very little information on reduced susceptibility to these biocides and its relationship with resistance to antibiotics. AIM: To determine the relationship between reduced susceptibility to biocides and the carriage of antiseptic resistance genes, cepA, qacΔE and qacE, as well as identifying the role of efflux pumps in conferring reduced susceptibility. METHODS: Susceptibility was assessed for five biocides: chlorhexidine, benzalkonium chloride, Trigene, MediHex-4, Mediscrub; and for 11 antibiotics against 64 isolates of Klebsiella pneumoniae. Susceptibility to all compounds was tested by the agar double dilution method (DDM) and the effect of efflux pumps on biocides determined by repeating the susceptibility studies in the presence of the efflux pump inhibitor carbonyl cyanide m-chlorophenyl hydrazone (CCCP). The presence of the cepA, qacΔE and qacE genes was identified by polymerase chain reaction. FINDINGS: The bacteria were not widely antibiotic resistant though a few showed reduced susceptibility to cefoxitin, chloramphenicol and rifampicin and later-generation cephalosporins but not to carbapenems. Biocide susceptibility, tested by DDM, showed that 50, 49 and 53 strains had reduced susceptibility to chlorhexidine, Trigene and benzalkonium chloride, respectively. The antiseptic resistance genes cepA, qacΔE and qacE were found in 56, 34 and one isolates respectively and their effects as efflux pumps were determined by CCCP (10 mg/L), which decreased the minimum inhibitory concentrations (MICs) of chlorhexidine and Medihex-4 by 2-128-fold but had no impact on the MICs of benzalkonium chloride, Trigene and Mediscrub. CONCLUSION: There was a close link between carriage of efflux pump genes, cepA, qacΔE and qacE genes and reduced biocide susceptibility, but not antibiotic resistance, in K. pneumoniae clinical isolates.201222498639
228860.9921Resistance of Stenotrophomonas maltophilia to Fluoroquinolones: Prevalence in a University Hospital and Possible Mechanisms. OBJECTIVE: The purpose of this study was to investigate the clinical distribution and genotyping of Stenotrophomonas maltophilia, its resistance to antimicrobial agents, and the possible mechanisms of this drug resistance. METHODS: S. maltophilia isolates were collected from clinical specimens in a university hospital in Northwestern China during the period between 2010 and 2012, and were identified to the species level with a fully automated microbiological system. Antimicrobial susceptibility testing was performed for S. maltophilia with the Kirby-Bauer disc diffusion method. The minimal inhibitory concentrations (MICs) of norfloxacin, ofloxacin, chloramphenicol, minocycline, ceftazidime, levofloxacin and ciprofloxacin against S. maltophilia were assessed using the agar dilution method, and changes in the MIC of norfloxacin, ciprofloxacin and ofloxacin were observed after the addition of reserpine, an efflux pump inhibitor. Fluoroquinolone resistance genes were detected in S. maltophilia using a polymerase chain reaction (PCR) assay, and the expression of efflux pump smeD and smeF genes was determined using a quantitative fluorescent (QF)-PCR assay. Pulsed-field gel electrophoresis (PFGE) was employed to genotype identified S. maltophilia isolates. RESULTS: A total of 426 S. maltophilia strains were isolated from the university hospital from 2010 to 2012, consisting of 10.1% of total non-fermentative bacteria. The prevalence of norfloxacin, ciprofloxacin and ofloxacin resistance was 32.4%, 21.9% and 13.2% in the 114 S. maltophilia isolates collected from 2012, respectively. Following reserpine treatment, 19 S. maltophilia isolates positive for efflux pump were identified, and high expression of smeD and smeF genes was detected in two resistant isolates. gyrA, parC, smeD, smeE and smeF genes were detected in all 114 S. maltophilia isolates, while smqnr gene was found in 25.4% of total isolates. Glu-Lys mutation (GAA-AAA) was detected at the 151th amino acid of the gyrA gene, while Gly-Arg mutation (GGC-CGC) was found at the 37th amino acid of the parC gene. However, no significant difference was observed in the prevalence of gyrA or parC mutation between fluoroquinolone-resistant and -susceptible isolates (p> 0.05). The smqnr gene showed 92% to 99% heterogenicity among the 14 S. maltophilia clinical isolates. PFGE of 29 smqnr gene-positive S. maltophilia clinical isolates revealed 25 PFGE genotypes and 28 subgenotypes. CONCLUSIONS: Monitoring the clinical distribution and antimicrobial resistance of S. maltophilia is of great significance for the clinical therapy of bacterial infections. Reserpine is effective to inhibit the active efflux of norfloxacin, ciprofloxacin and ofloxacin on S. maltophilia and reduce MIC of fluoroquinolones against the bacteria. The expression of efflux pump smeD and smeF genes correlates with the resistance of S. maltophilia to fluoroquinolones.201525985315
126070.9921Isolation, 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
124780.9919Antibiotic 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
537590.9919Mechanism of Eravacycline Resistance in Clinical Enterococcus faecalis Isolates From China. Opportunistic infections caused by multidrug-resistant Enterococcus faecalis strains are a significant clinical challenge. Eravacycline (Erava) is a synthetic fluorocycline structurally similar to tigecycline (Tige) that exhibits robust antimicrobial activity against Gram-positive bacteria. This study investigated the in vitro antimicrobial activity and heteroresistance risk of Eravacycline (Erava) in clinical E. faecalis isolates from China along with the mechanism of Erava resistance. A total of 276 non-duplicate E. faecalis isolates were retrospectively collected from a tertiary care hospital in China. Heteroresistance to Erava and the influence of tetracycline (Tet) resistance genes on Erava susceptibility were examined. To clarify the molecular basis for Erava resistance, E. faecalis variants exhibiting Erava-induced resistance were selected under Erava pressure. The relative transcript levels of six candidate genes linked to Erava susceptibility were determined by quantitative reverse-transcription PCR, and their role in Erava resistance and heteroresistance was evaluated by in vitro overexpression experiments. We found that Erava minimum inhibitory concentrations (MICs) against clinical E. faecalis isolates ranged from ≤0.015 to 0.25 mg/l even in strains harboring Tet resistance genes. The detection frequency of Erava heteroresistance in isolates with MICs ≤ 0.06, 0.125, and 0.25 mg/l were 0.43% (1/231), 7.5% (3/40), and 0 (0/5), respectively. No mutations were detected in the 30S ribosomal subunit gene in Erava heteroresistance-derived clones, although mutations in this subunit conferred cross resistance to Tige in Erava-induced resistant E. faecalis. Overexpressing RS00630 (encoding a bone morphogenetic protein family ATP-binding cassette transporter substrate-binding protein) in E. faecalis increased the frequency of Erava and Tige heteroresistance, whereas RS12140, RS06145, and RS06880 overexpression conferred heteroresistance to Tige only. These results indicate that Erava has potent in vitro antimicrobial activity against clinical E. faecalis isolates from China and that Erava heteroresistance can be induced by RS00630 overexpression.202032523563
5407100.9918Resistance 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
1245110.9918Mutation-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
1250120.9918Distribution 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
1265130.9918Coagulase-negative staphylococci (CoNS) isolated from ready-to-eat food of animal origin--phenotypic and genotypic antibiotic resistance. The aim of this work was to study the pheno- and genotypical antimicrobial resistance profile of coagulase negative staphylococci (CoNS) isolated from 146 ready-to-eat food of animal origin (cheeses, cured meats, sausages, smoked fishes). 58 strains were isolated, they were classified as Staphylococcus xylosus (n = 29), Staphylococcus epidermidis (n = 16); Staphylococcus lentus (n = 7); Staphylococcus saprophyticus (n = 4); Staphylococcus hyicus (n = 1) and Staphylococcus simulans (n = 1) by phenotypic and genotypic methods. Isolates were tested for resistance to erythromycin, clindamycin, gentamicin, cefoxitin, norfloxacin, ciprofloxacin, tetracycline, tigecycline, rifampicin, nitrofurantoin, linezolid, trimetoprim, sulphamethoxazole/trimethoprim, chloramphenicol, quinupristin/dalfopristin by the disk diffusion method. PCR was used for the detection of antibiotic resistance genes encoding: methicillin resistance--mecA; macrolide resistance--erm(A), erm(B), erm(C), mrs(A/B); efflux proteins tet(K) and tet(L) and ribosomal protection proteins tet(M). For all the tet(M)-positive isolates the presence of conjugative transposons of the Tn916-Tn1545 family was determined. Most of the isolates were resistant to cefoxitin (41.3%) followed by clindamycin (36.2%), tigecycline (24.1%), rifampicin (17.2%) and erythromycin (13.8%). 32.2% staphylococcal isolates were multidrug resistant (MDR). All methicillin resistant staphylococci harboured mecA gene. Isolates, phenotypic resistant to tetracycline, harboured at least one tetracycline resistance determinant on which tet(M) was most frequent. All of the isolates positive for tet(M) genes were positive for the Tn916-Tn1545 -like integrase family gene. In the erythromycin-resistant isolates, the macrolide resistance genes erm(C) or msr(A/B) were present. Although coagulase-negative staphylococci are not classical food poisoning bacteria, its presence in food could be of public health significance due to the possible spread of antibiotic resistance.201525475289
1249140.9918High-Level Resistance to Aminoglycosides due to 16S rRNA Methylation in Enterobacteriaceae Isolates. Introduction: High-level aminoglycoside resistance due to methylase genes has been reported in several countries. The purpose of this study was to investigate the diversity of the genes encoding 16S rRNA methylase and their association with resistance phenotype in Enterobacteriacae isolates. Materials and Methods: Based on sampling size formula, from February to August 2014, a total of 307 clinical Enterobacteriaceae isolates were collected from five hospitals in northwest Iran. The disk diffusion method for amikacin, gentamicin, tobramycin, kanamycin, and streptomycin, as well as the minimum inhibitory concentration (MIC) for aminoglycosides (except streptomycin), was used. Six 16S rRNA methylase genes (armA, npmA, and rmtA-D) were screened by PCR and sequencing assays. Results: In this study, 220 (71.7%) of 307 isolates were aminoglycoside resistant and 40 isolates (18.2%, 40/220) were positive for methylase genes. The frequency of armA, rmtC, npmA, rmtB, and rmtA genes was 9.5%, 4.5%, 3.6%, 2.3%, and 1%, respectively. The rmtD gene was not detected in the tested bacteria. Sixty percent of positive methylase gene isolates displayed high-level resistance (MIC ≥512 μg/mL to amikacin and kanamycin; and MIC ≥128 μg/mL to gentamicin and tobramycin). Conclusions: The prevalence of resistance to aminoglycoside in Iran is high. Furthermore, there is a statistically significant association between amikacin and kanamycin resistance with the presence of rmtC and rmtB genes.201931211656
1259150.9917Tetracycline resistance potential of heterotrophic bacteria isolated from freshwater fin-fish aquaculture system. AIMS: This study investigated the tetracycline resistance potential of heterotrophic bacteria isolated from twenty-four freshwater fin-fish culture ponds in Andhra Pradesh, India. METHODS AND RESULTS: A total of 261 tetracycline resistant bacteria (tetR) were recovered from pond water, pond sediment, fish gills, fish intestine, and fish feed. Bacteria with high tetracycline resistance (tetHR) (n = 30) that were resistant to tetracycline concentrations above 128  μg mL-1 were predominantly Lactococcus garvieae followed by Enterobacter spp., Lactococcus lactis, Enterobacter hormaechei, Staphylococcus arlettae, Streptococcus lutetiensis, Staphylococcus spp., Brevundimonas faecalis, Exiguobacterium profundum, Lysinibacillus spp., Stutzerimonas stutzeri, Enterobacter cloacae, and Lactococcus taiwanensis. Resistance to 1024 μg mL-1 of tetracycline was observed in L. garvieae, S. arlettae, Enterobacter spp., B. faecalis. Tet(A) (67%) was the predominant resistance gene in tetHR followed by tet(L), tet(S), tet(K), and tet(M). At similar concentrations of exposure, tetracycline procured at the farm level (69.5% potency) exhibited lower inhibition against tetHR bacteria compared to pure tetracycline (99% potency). The tetHR bacteria showed higher cross-resistance to furazolidone (100%) followed by co-trimoxazole (47.5%) and enrofloxacin (11%). CONCLUSIONS: The maximum threshold of tetracycline resistance at 1024 μg mL-1 was observed in S. arlettae, Enterobacter spp., B. faecalis, and L. garvieae and tet(A) was the major determinant found in this study.202336958862
1248160.9916Clonal Dissemination of Clinical Isolates of Acinetobacter baumannii Carriers of 16S rRNA Methylase Genes in an Oncological Hospital in Recife, Brazil. 16S rRNA methylases confer high-level resistance to aminoglycosides which are used to treat serious infections caused by gram-negative bacteria, such as Acinetobacter spp. Some genes encoding these enzymes are disseminated worldwide, while others were detected in only some countries. The objective was to characterize the susceptibility profile to aminoglycosides (amikacin and gentamicin) of clinical isolates of Acinetobacter spp. from an oncological hospital in Recife, and given the resistance to both antimicrobials, to characterize minimal inhibitory concentrations (MICs) of amikacin, gentamicin and tobramycin, the occurrence of 16S rRNA methylase genes (armA, rmtB, rmtC and rmtD) and of ß-lactamase gene (bla(KPC)) and the clonal profile. Isolates resistant to both antimicrobials, amikacin and gentamicin, were selected by disk diffusion technique in Mueller-Hinton agar and identified. Broth microdilution was conducted to determine MICs of amikacin, gentamicin, and tobramycin. These isolates were subjected to polymerase chain reaction and pulsed-field gel electrophoresis. Among 23 analyzed isolates, 12 (52.2%) were resistant to gentamicin and amikacin and identified as Acinetobacter baumannii. Among these, 11 (91.7%), 12 (100%), and 9 (75%) isolates showed respectively MICs > 256 µg/mL of amikacin, > 64 µg/mL of gentamicin, and > 64 µg/mL of tobramycin. The armA gene was found in 12 (100%) isolates and 6 (50%) showed coexistence of armA, rmtB, and rmtC genes. The rmtD and bla(KPC) genes were not detected. These isolates showed high genetic similarity (92%) and were classified as clone A. Elaboration and fulfillment of measures are thus essential to prevent the spread of this resistance mechanism.202031655862
5414170.9916Genetic determinants of antimicrobial resistance in Gram positive bacteria from organic foods. Bacterial biocide resistance is becoming a matter of concern. In the present study, a collection of biocide-resistant, Gram-positive bacteria from organic foods (including 11 isolates from genus Bacillus, 25 from Enterococcus and 10 from Staphylococcus) were analyzed for genes associated to biocide resistance efflux pumps and antibiotic resistance. The only qac-genes detected were qacA/B (one Bacillus cereus isolate) and smr (one B. cereus and two Staphylococcus saprophyticus isolates). Efflux pump genes efrA and efrB genes were detected in Staphylococcus (60% of isolates), Bacillus (54.54%) and Enterococcus (24%); sugE was detected in Enterococcus (20%) and in one Bacillus licheniformis; mepA was detected in Staphylococcus (60%) and in one Enterococcus isolate (which also carried mdeA), and norE gene was detected only in one Enterococcus faecium and one S. saprophyticus isolate. An amplicon for acrB efflux pump was detected in all but one isolate. When minimal inhibitory concentrations (MICs) were determined, it was found that the addition of reserpine reduced the MICs by eight fold for most of the biocides and isolates, corroborating the role of efflux pumps in biocide resistance. Erythromycin resistance gene ermB was detected in 90% of Bacillus isolates, and in one Staphylococcus, while ereA was detected only in one Bacillus and one Staphyloccus, and ereB only in one Staphylococcus. The ATP-dependent msrA gene (which confers resistance to macrolides, lincosamides and type B streptogramins) was detected in 60% of Bacillus isolates and in all staphylococci, which in addition carried msrB. The lincosamide and streptogramin A resistance gene lsa was detected in Staphylococcus (40%), Bacillus (27.27%) and Enterococcus (8%) isolates. The aminoglycoside resistance determinant aph (3_)-IIIa was detected in Staphylococcus (40%) and Bacillus (one isolate), aph(2_)-1d in Bacillus (27.27%) and Enterococcus (8%), aph(2_)-Ib in Bacillus (one isolate), and the bifunctional aac(6_)1e-aph(2_)-Ia in Staphylococcus (20%), Enterococcus (8%) and Bacillus (one isolate). Chloramphenicol resistance cat gene was detected in Enterococcus (8%) and Staphylococcus (20%), and blaZ only in Staphylococcus (20%). All other antibiotic or biocide resistance genes investigated were not detected in any isolate. Isolates carrying multiple biocide and antibiotic determinants were frequent among Bacillus (36.36%) and Staphylococcus (50%), but not Enterococcus. These results suggest that biocide and antibiotic determinants may be co-selected.201424361832
2478180.9915Study on the resistance mechanism via outer membrane protein OprD2 and metal β-lactamase expression in the cell wall of Pseudomonas aeruginosa. The aim of the present study was to evaluate the imipenem-resistant mechanism via the outer membrane protein (OMP) OprD2 and metal β-lactamase expression in the cell wall of Pseudomonas aeruginosa. The Pseudomonas aeruginosa was clinically separated and validated by VITEK-2 full-automatic bacteria analyzer. Drug resistance, sensitive antibiotics and minimum inhibitory concentration (MIC) were tested using the drug sensitivity analysis system. The phenotype positive strains of MBL genes were screened using the Kirby-Bauer diffusion method by adding metal ion-chelating agent EDTA on the imipenem susceptibility paper. IMP-1, VIM-1 and SPM metaloenzyme genes were tested by polymerase chain reaction (PCR)-telomeric repeat amplification protocol (TRAP). The OMP OprD2 genes were tested by PCR-TRAP, and the protein expression was tested using western blot analysis. The location of OMP OprD2 was confirmed using the sodium salicylate inhibition test. The results showed that 80 portions (40%) of MBL-positive strains were screened out of 200 specimens. Imipenem-resistant Pseudomonas aeruginosa (IRPA) and MIC values were significantly higher than quality control bacteria and control bacteria (P<0.05). A total of 35 cases with IMP-1 positive, 20 with VIM-1 positive, 16 with SPM positive, 5 with 2 positive genes and 4 with 3 positive genes were screened among MBL positive strains. A total of 150 portions (75%) of OprD2 deficiencies were screened from 200 specimens. The standard strains and sensitive strains showed OprD2 protein bands at 45 kDa while no OprD2 protein bands appeared in OprD2 deficiency strains. It was in accordance with gene detection. In conclusion, OMP OprD2 deficiency and MBL phenotype positivity may be important mechanisms of IRPA.201627882088
1263190.9915Antimicrobial Resistance and Antimicrobial Activity of Staphylococcus lugdunensis Obtained from Two Spanish Hospitals. Staphylococcus lugdunensis is a coagulase-negative-staphylococci (CoNS) that lately has gained special attention in public health as a human pathogen and also as a bacteriocin-producer bacteria. In this study, we characterized 56 S. lugdunensis isolates recovered from human samples in two Spanish hospitals. Antimicrobial susceptibility testing was performed and antimicrobial resistance and virulence genotypes were determined. Antimicrobial activity (AA) production was evaluated by the spot-on-lawn method against 37 indicator bacteria, including multidrug-resistant (MDR) isolates, and the presence of the lugD gene coding for lugdunin bacteriocin was analyzed by PCR. The antibiotic resistance detected was as follows (% resistance/genes detected): penicillin (44.6%/blaZ), oxacillin (1.8%/mecA on SCCmec-V), erythromycin-clindamycin inducible (7.1%/erm(C), msrA), tetracycline (5.3%/tetK), gentamicin and/or tobramycin (3.6%/ant(4')-Ia, acc(6')-aph(2″)), and fosfomycin (21.4%). A MDR phenotype was detected in 5% of isolates. Twenty-one of the S. lugdunensis isolates showed susceptibility to all 20 antibiotics tested (37.5%). The screening for AA revealed 23 antimicrobial producer (AP) isolates with relevant inhibition against coagulase-positive-staphylococci (CoPS), including both methicillin-susceptible and -resistant S. aureus. The lugD gene was detected in 84% of the 56 S. lugdunensis isolates. All of the AP S. lugdunensis isolates (n = 23) carried the lugD gene and it was also detected in 24 of the non-AP isolates, suggesting different gene expression levels. One of the AP isolates stood out due to its high antimicrobial activity against more than 70% of the indicator bacteria tested, so it will be further characterized at genomic and proteomic level.202235893538