Phenotypic and genotypic antimicrobial resistance profiles of fecal lactobacilli from domesticated pigeons in Poland. - Related Documents




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238701.0000Phenotypic and genotypic antimicrobial resistance profiles of fecal lactobacilli from domesticated pigeons in Poland. Lactobacillus species play an important role in the host and although they are non-pathogenic, they could act as reservoirs for antibiotic resistance genes, with the potential risk of transfer to other bacteria inhabiting the gastrointestinal tract. The aim of this study was to identify Lactobacillus species derived from feces of domesticated pigeons and to characterize their phenotypic and genotypic antimicrobial resistance (AMR) profiles. A total of 57 Lactobacillus isolates were classified into six species using the MALDI-TOF technique and 16S rDNA restriction analysis. Strains of L. ingluviei (31%), L. salivarius (28%) and L. agilis (23%) were the dominant species isolated. Determination of antimicrobial susceptibility by the microdilution broth method showed widespread resistance to kanamycin (89%), tetracycline (84%), streptomycin (63%), and enrofloxacin (37%). Less than 30% of the isolates were resistant to erythromycin, lincosamides, gentamycin, chloramphenicol and vancomycin. Over half (51%) of the lactobacilli were classified as multidrug resistant. Tet genes were detected in 79% of isolates; the lnuA, cat, ermB, ermC, ant(6)-Ia, ant(4')-Ia, and int-Tn genes were found at a lower frequency. Sequence analysis of the quinolone resistance-determining region (QRDR)of the gyrA gene showed that fluoroquinolone resistance in lactobacilli was the result of a mutation that lead to a change in the amino acid sequence (Ser83→Tyr/Leu/Phe). Domesticated pigeons could be a reservoir for AMR Lactobacillus strains and AMR genes.202032781109
238910.9999Antibiotic Resistance of LACTOBACILLUS Strains. The study provides phenotypic and molecular analyses of the antibiotic resistance in 20 Lactobacillus strains including 11 strains newly isolated from fermented plant material. According to the results of disc diffusion method, 90% of tested lactobacilli demonstrated sensitivity to clindamycin and 95% of strains were susceptible to tetracycline, erythromycin, and rifampicin. Ampicillin and chloramphenicol were found to inhibit all bacteria used in this study. The vast majority of tested strains revealed phenotypic resistance to vancomycin, ciprofloxacin, and aminoglycosides. Most of Lactobacillus strains showed high minimum inhibitory concentrations (MICs) of cefotaxime, ceftriaxone, and cefazolin and therefore were considered resistant to cephalosporins. All the strains exhibited multidrug resistance. The occurrence of resistance genes was associated with phenotypic resistance, with the exception of phenotypically susceptible strains that contained genes for tetracycline (tetK, tetL) and erythromycin (ermB, mefA) resistance. The vanX gene for vancomycin resistance was among the most frequently identified among the lactobacilli (75% of strains), but the occurrence of the parC gene for ciprofloxacin resistance was sporadic (20% of strains). Our results mainly evidence the intrinsic nature of the resistance to aminoglycosides in lactobacilli, though genes for enzymatic modification of streptomycin aadA and aadE were found in 20% of tested strains. The occurrence of extended spectrum beta-lactamases (ESBL) was unknown in Lactobacillus, but our results revealed the blaTEM gene in 80% of strains, whereas blaSHV and blaOXA-1 genes were less frequent (20% and 15% of strains, respectively).201931555856
239920.9999Ready-to-eat dairy products as a source of multidrug-resistant Enterococcus strains: Phenotypic and genotypic characteristics. The enterococci are ubiquitous bacteria able to colonize the human and animal gastrointestinal tracts and fresh and fermented food products. Their highly plastic genome allows Enterococcus spp. to gain resistance to multiple antibiotics, making infections with these organisms difficult to treat. Food-borne enterococci could be carriers of antibiotic resistance determinants. The goal of this work was to study the characteristics of Enterococcus spp. in fermented milk products from Poland and their antibiotic resistance gene profiles. A total of 189 strains were isolated from 182 dairy products out of 320 samples tested. The predominant species were Enterococcus faecium (53.4%) and Enterococcus faecalis (34.4%). Isolates were resistant to streptomycin (29.1%), erythromycin (14.3%), tetracycline (11.6%), rifampicin (8.7%), and tigecycline (8.1%). We also detected 2 vancomycin-resistant and 3 linezolid-resistant strains; however, no vanA or vanB genes were identified. A total of 57 high-level aminoglycoside resistance strains (30.2%) were identified, most of which have the ant(6')-Ia gene, followed by the aac(6')-Ie-aph(2″)-Ia and aph(3″)-IIIa genes. Resistance to tetracycline was most often conferred by tetM and tetL genes. Macrolide resistance was most frequently encoded by ermB and ermA genes. Conjugative mobile genetic element (transposon Tn916-Tn1545) was identified in 15.3% of the strains, including 96.3% of strains harboring the tetM gene. This study found that enterococci are widely present in retail ready-to-eat dairy products in Poland. Many isolated strains are antibiotic resistant and carry transferable resistance genes, which represent a potential source of transmission of multidrug-resistant bacteria to humans.202032197843
238830.9999Antibiotic resistance in lactic acid bacteria isolated from some pharmaceutical and dairy products. A total of 244 lactic acid bacteria (LAB) strains were isolated from 180 dairy and pharmaceutical products that were collected from different areas in Minia governorate, Egypt. LAB were identified phenotypically on basis of morphological, physiological and biochemical characteristics. Lactobacillus isolates were further confirmed using PCR-based assay. By combination of phenotypic with molecular identification Lactobacillus spp. were found to be the dominant genus (138, 76.7%) followed by Streptococcus spp. (65, 36.1%) and Lactococcus spp. (27, 15%). Some contaminant organisms such as (Staphylococcus spp., Escherichia coli, Salmonella spp., mould and yeast) were isolated from the collected dairy samples but pharmaceutical products were free of such contaminants. Susceptibility of LAB isolates to antibiotics representing all major classes was tested by agar dilution method. Generally, LAB were highly susceptible to Beta-lactams except penicillin. Lactobacilli were resistant to vancomycin, however lactococci and streptococci proved to be very susceptible. Most strains were susceptible to tetracycline and showed a wide range of streptomycin MICs. The MICs of erythromycin and clindamycin for most of the LAB were within the normal range of susceptibility. Sixteen Lactobacillus, 8 Lactococcus and 8 Streptococcus isolates including all tetracycline and/or erythromycin resistant strains were tested for the presence of tetracycline and/or erythromycin resistant genes [tet(M) and/or erm(B)]. PCR assays shows that some resistant strains harbor tet(M) and/or erm(B) resistance genes.201424948910
539840.9999Characterization and transfer of antimicrobial resistance in lactic acid bacteria from fermented dairy products in China. INTRODUCTION: Lactic acid bacteria (LAB) are commonly found in foods and are also natural intestinal inhabitants in humans and most animals. However, information regarding antimicrobial resistance and the transfer of resistance genes of LAB from fermented dairy products in China is limited. METHODOLOGY: In this study, LAB isolates (n = 82) of Lactobacillus (n = 43) and Streptococcus thermophilus (n = 39) were isolated from 51 commercial fermented food samples in China. All isolates were subjected to pulsed-field gel electrophoresis (PFGE), antimicrobial susceptibility, detecting resistance genes, as well as investigating the transferability of resistance genes. RESULTS: The 43 Lactobacillus isolates yielded 24 PFGE patterns and the 34 isolates of S. thermophilus generated 32 different PFGE patterns. Among the 43 Lactobacillus strains, the most commonly observed resistance was that to streptomycin (83.7%) and gentamycin (83.7%). Among the 39 S. thermophilus strains, the most frequently observed resistance was that to streptomycin (92.3%), gentamycin (87.2%), ciprofloxacin (79.5%), and chloramphenicol (71.8%), whereas the lowest level of resistance was that against erythromycin (7.7%). Antimicrobial resistance genes for erythromycin (emrB), gentamycin (aac(6')-aph(2")), streptomycin (ant(6)), sulfamethoxazole (sulI and sulII), tetracycline (tetM and tetS) were detected in the 18 resistance LAB strains. Conjugation experiments showed that tetM from L. delbrueckii subsp. bulgaricus R6 and tetS from L. plantarum R41 were successfully transferred to L. monocytogenes by filter mating. CONCLUSIONS: LAB strains could potentially act as reservoirs of resistance genes and play an active role in the transfer of resistance to humans via the food chain.201932036349
291050.9999Phenotypic and genotypic characterization of tetracycline and minocycline resistance in Clostridium perfringens. The aim of this study was to determine the incidence of tetracycline resistance and the prevalence of tetracycline-resistance genes in strains of Clostridium perfringens isolated from different sources between 1994 and 2005. Susceptibility to tetracycline and minocycline in strains from humans (35 isolates), chickens (15 isolates), food (21 isolates), soil (16 isolates) and veterinary sources (6 isolates) was determined, and tetracycline-resistance genes were detected. Resistance was most common in strains isolated from chickens, followed by those from soils, clinical samples and foods. The most highly resistant strains were found among clinical and food isolates. tetA(P) was the most common resistance gene, and along with tetB(P) was found in all resistant strains and some sensitive strains. One tetracycline-resistant food isolate had an intact tet(M) gene. However, PCR fragments of 0.4 or 0.8 kb with high degrees of identity to parts of the tet(M) sequences of other bacteria were found, mainly in clinical isolates, and often in isolates with tetB(P). No correlation between level of sensitivity to tetracycline or minocycline and the presence of tetA(P), tetB(P) or part of tet(M) was found. The presence of part of tet(M) in some strains of C. perfringens containing tetB(P) may have occurred by recent gene transfer.201020661548
290960.9999Determination of the prevalence of antimicrobial resistance genes in canine Clostridium perfringens isolates. Clostridium perfringens is a well documented cause of a mild self-limiting diarrhea and a potentially fatal acute hemorrhagic diarrheal syndrome in the dog. A recent study documented that 21% of canine C. perfringens isolates had MIC's indicative of resistance to tetracycline, an antimicrobial commonly recommended for treatment of C. perfringens-associated diarrhea. The objective of the present study was to further evaluate the antimicrobial susceptibility profiles of these isolates by determining the prevalence of specific resistance genes, their expression, and ability for transference between bacteria. One hundred and twenty-four canine C. perfringens isolates from 124 dogs were evaluated. Minimum inhibitory concentrations of tetracycline, erythromycin, tylosin, and metronidazole were determined using the CLSI Reference Agar Dilution Method. All isolates were screened for three tetracycline resistance genes: tetA(P), tetB(P) and tetM, and two macrolide resistance genes: ermB and ermQ, via PCR using primer sequences previously described. Ninety-six percent (119/124) of the isolates were positive for the tetA(P) gene, and 41% (51/124) were positive for both the tetA(P) and tetB(P) genes. No isolates were positive for the tetB(P) gene alone. Highly susceptible isolates (MIC< or = 4 microg/ml) were significantly more likely to lack the tetB(P) gene. One isolate (0.8%) was positive for the ermB gene, and one isolate was positive for the ermQ gene. The tetM gene was not found in any of the isolates tested. Two out of 15 tested isolates (13%) demonstrated transfer of tetracycline resistance via bacterial conjugation. Tetracycline should be avoided for the treatment of C. perfringens-associated diarrhea in dogs because of the relatively high prevalence of in vitro resistance, and the potential for conjugative transfer of antimicrobial resistance.200616330169
290870.9998Detection of tetracycline and macrolide resistance determinants in Enterococci of animal and environmental origin using multiplex PCR. An occurrence of resistance to tetracycline (TET) and erythromycin (ERY) was ascertained in 82 isolates of Enterococcus spp. of animal and environmental origin. Using E test, 33 isolates were resistant to TET and three isolates to ERY. Using polymerase chain reaction (PCR; single and multiplex), the TET determinants tet(M) and tet(L) were detected in 35 and 13 isolates, respectively. Twelve isolates carried both tet(M) and tet(L) genes. Eight isolates possessed ermB gene associated with ERY resistance. Multiplex PCR was shown to be a suitable method for simultaneous determination of all three resistance determinants that occurred most frequently in bacteria isolated from poultry. This study also demonstrates that gastrointestinal tract of broilers may be a reservoir of enterococci with acquired resistance to both TET and ERY that can be transferred to humans via food chain.201121656006
267180.9998Toxinotyping and molecular characterization of antimicrobial resistance in Clostridium perfringens isolated from different sources of livestock and poultry. The present study was designed to understand the presence of antimicrobial resistance among the prevalent toxinotypes of Clostridium perfringens recovered from different animals of Tamil Nadu, India. A total of 75 (10.76%) C. perfringens were isolated from 697 multi-species fecal and intestinal content samples. C. perfringens type A (90.67%), type C (2.67%), type D (4%) and type F (2.67%) were recovered. Maximum number of isolates were recovered from dog (n = 20, 24.10%) followed by chicken (n = 19, 5.88%). Recovered isolates were resistant to gentamicin (44.00%), erythromycin (40.00%), bacitracin (40.00%), and tetracycline (26.67%), phenotypically and most of the isolates were found to be resistant to multiple antimicrobials. Genotypic characterization revealed that tetracycline (41.33%), erythromycin (34.66%) and bacitracin (17.33%) resistant genes were present individually or in combination among the isolates. Combined results of phenotypic and genotypic characterization showed the highest percentage of erythromycin resistance (26.66%) among the isolates. None of the isolates showed amplification for lincomycin resistance genes. The correlation matrix analysis of genotypic resistance showed a weak positive relationship between the tetracycline and bacitracin resistance while a weak negative relationship between the tetracycline and erythromycin resistance. The present study thus reports the presence of multiple-resistance genes among C. perfringens isolates that may be involved in the dissemination of resistance to other bacteria present across species. Further insights into the genome can help to understand the mechanism involved in gene transfer so that measures can be taken to prevent the AMR spread.202133220406
240690.9998Prevalence of antibiotic resistance genes in staphylococci isolated from ready-to-eat meat products. Prevalence of mecA, blaZ, tetO/K/M, ermA/B/C, aph, and vanA/B/C/D genes conferring resistance to oxacillin, penicillin, tetracycline, erythromycin, gentamicin, and vancomycin was investigated in 65 staphylococcal isolates belonging to twelve species obtained from ready-to-eat porcine, bovine, and chicken products. All coagulase negative staphylococci (CNS) and S. aureus isolates harbored at least one antibiotic resistance gene. None of the S. aureus possessed more than three genes, while 25% of the CNS isolates harbored at least four genes encoding resistance to clinically used antibiotics. In 15 CNS isolates the mecA gene was detected, while all S. aureus isolates were mecA-negative. We demonstrate that in ready-to-eat food the frequency of CNS harboring multiple antibiotic resistance genes is higher than that of multiple resistant S. aureus, meaning that food can be considered a reservoir of bacteria containing genes potentially contributing to the evolution of antibiotic resistance in staphylococci.201222844699
2918100.9998Antibiotic resistance genes in multidrug-resistant Enterococcus spp. and Streptococcus spp. recovered from the indoor air of a large-scale swine-feeding operation. AIMS: In this study, multidrug-resistant bacteria previously recovered from the indoor air of a large-scale swine-feeding operation were tested for the presence of five macrolide, lincosamide and streptogramin (MLS) resistance genes and five tetracycline (tet) resistance genes. METHODS AND RESULTS: Enterococcus spp. (n = 16) and Streptococcus spp. (n =16) were analysed using DNA-DNA hybridization, polymerase chain reaction (PCR) and oligoprobing of PCR products. All isolates carried multiple MLS resistance genes, while 50% of the Enterococcus spp. and 44% of the Streptococcus spp. also carried multiple tet resistance genes. All Enterococcus spp. carried erm(A) and erm(B), 69% carried erm(F), 44% carried mef(A), 75% carried tet(M), 69% carried tet(L) and 19% carried tet(K). All Streptococcus spp. carried erm(B), 94% carried erm(F), 75% carried erm(A), 38% carried mef(A), 50% carried tet(M), 81% carried tet(L) and 13% carried tet(K). CONCLUSIONS: Multidrug resistance among airborne bacteria recovered from a swine operation is encoded by multiple MLS and tet resistance genes. These are the first data regarding resistance gene carriage among airborne bacteria from swine-feeding operations. SIGNIFICANCE AND IMPACT OF THE STUDY: The high prevalence of multiple resistance genes reported here suggests that airborne Gram-positive bacteria from swine operations may be important contributors to environmental reservoirs of resistance genes.200617032228
2670110.9998Molecular characterisation and antimicrobial resistance of Streptococcus agalactiae isolates from dairy farms in China. INTRODUCTION: Streptococcus agalactiae (S. agalactiae) is a pathogen causing bovine mastitis that results in considerable economic losses in the livestock sector. To understand the distribution and drug resistance characteristics of S. agalactiae from dairy cow mastitis cases in China, multilocus sequence typing (MLST) was carried out and the serotypes and drug resistance characteristics of the bacteria in the region were analysed. MATERIAL AND METHODS: A total of 21 strains of bovine S. agalactiae were characterised based on MLST, molecular serotyping, antimicrobial susceptibility testing, and the presence of drug resistance genes. RESULTS: The serotypes were mainly Ia and II, accounting for 47.6% and 42.9% of all serotypes, respectively. Five sequence types (STs) were identified through MLST. The ST103 and ST1878 strains were predominant, with rates of 52.4% and 28.6%, respectively. The latter is a novel, previously uncharacterised sequence type. More than 90% of S. agalactiae strains were susceptible to penicillin, oxacillin, cephalothin, ceftiofur, gentamicin, florfenicol and sulfamethoxazole. The bacteria showed high resistance to tetracycline (85.7%), clindamycin (52.1%) and erythromycin (47.6%). Resistant genes were detected by PCR, the result of which showed that 47.6%, 33.3% and 38.1% of isolates carried the tet(M), tet(O) and erm(B) genes, respectively. CONCLUSION: The results of this study indicate that S. agalactiae show a high level of antimicrobial resistance. It is necessary to monitor the pathogens of mastitis to prevent the transmission of these bacteria.202338143824
5935120.9998Antibiotic resistance genes in anaerobic bacteria isolated from primary dental root canal infections. Fourty-one bacterial strains isolated from infected dental root canals and identified by 16S rRNA gene sequence were screened for the presence of 14 genes encoding resistance to beta-lactams, tetracycline and macrolides. Thirteen isolates (32%) were positive for at least one of the target antibiotic resistance genes. These strains carrying at least one antibiotic resistance gene belonged to 11 of the 26 (42%) infected root canals sampled. Two of these positive cases had two strains carrying resistance genes. Six out of 7 Fusobacterium strains harbored at least one of the target resistance genes. One Dialister invisus strain was positive for 3 resistance genes, and 4 other strains carried two of the target genes. Of the 6 antibiotic resistance genes detected in root canal strains, the most prevalent were blaTEM (17% of the strains), tetW (10%), and ermC (10%). Some as-yet-uncharacterized Fusobacterium and Prevotella isolates were positive for blaTEM, cfxA and tetM. Findings demonstrated that an unexpectedly large proportion of dental root canal isolates, including as-yet-uncharacterized strains previously regarded as uncultivated phylotypes, can carry antibiotic resistance genes.201223108290
2903130.9998Soil Bacteria in Urban Community Gardens Have the Potential to Disseminate Antimicrobial Resistance Through Horizontal Gene Transfer. Fifteen soil and 45 vegetable samples from Detroit community gardens were analyzed for potential antimicrobial resistance contamination. Soil bacteria were isolated and tested by antimicrobial susceptibility profiling, horizontal gene transfer, and whole-genome sequencing. High-throughput 16S rRNA sequencing analysis was conducted on collected soil samples to determine the total bacterial composition. Of 226 bacterial isolates recovered, 54 were from soil and 172 from vegetables. A high minimal inhibitory concentration (MIC) was defined as the MIC greater than or equal to the resistance breakpoint of Escherichia coli for Gram-negative bacteria or Staphylococcus aureus for Gram-positive bacteria. The high MIC was observed in 63.4 and 69.8% of Gram-negative isolates from soil and vegetables, respectively, against amoxicillin/clavulanic acid, as well as 97.5 and 82.7% against ampicillin, 97.6 and 90.7% against ceftriaxone, 85.4 and 81.3% against cefoxitin, 65.8 and 70.5% against chloramphenicol, and 80.5 and 59.7% against ciprofloxacin. All Gram-positive bacteria showed a high MIC to gentamicin, kanamycin, and penicillin. Forty of 57 isolates carrying tetM (70.2%) successfully transferred tetracycline resistance to a susceptible recipient via conjugation. Whole-genome sequencing analysis identified a wide array of antimicrobial resistance genes (ARGs), including those encoding AdeIJK, Mex, and SmeDEF efflux pumps, suggesting a high potential of the isolates to become antimicrobial resistant, despite some inconsistency between the gene profile and the resistance phenotype. In conclusion, soil bacteria in urban community gardens can serve as a reservoir of antimicrobial resistance with the potential to transfer to clinically important pathogens, resulting in food safety and public health concerns.202134887843
5936140.9998Antibiotic Resistance Characterization and Molecular Characteristics of Enterococcus Species Isolated from Combination Probiotic Preparations in China. Enterococci can act as reservoirs for antibiotic-resistant genes that are potentially at risk of being transferred to other bacteria that inhabit in the gastrointestinal tract. The aim of this study was to determine the phenotypic and molecular characteristics of antibiotic-resistant enterococci isolated from probiotic preparations. In total, we isolated 15 suspected Enterococcus species from 5 compound probiotics, which were identified by 16S rDNA as 12 Enterococcus faecium and 3 Enterococcus faecalis. Determination of antimicrobial susceptibility by the microdilution broth method showed widespread resistance to sulfamethoxazole (100%), norfloxacin (99.3%), azithromycin (99.3%), gentamicin (86.7%), and chloramphenicol (20%). Whole genome sequencing of five resistant strains revealed that all had circular DNA chromosomes and that E. faecium J-1-A to J-4-A contained a plasmid, while E. faecalis J-5-A did not. The results of the resistance gene analysis revealed that each strain contained approximately 30 resistance genes, with the antibiotic resistance genes and the multidrug resistance efflux pump genes mdtG, lmrC, and lmrD detected in all strains. The chloramphenicol resistance genes ykkC and ykkD were first identified in E. faecalis. And there were 21, 19, 21, 21, and 29 virulence factors involved in strains, respectively. Further analysis of the gene islands (GIs) revealed that each strain contained more than 10 GIs. The above results confirm the existence of hidden dangers in the safety of probiotics and remind us to carefully select probiotic preparations containing enterococcal strains to avoid the potential spread of resistance and pathogenicity.202437824752
5997150.9998Resistance of potential probiotic lactic acid bacteria and bifidobacteria of African and European origin to antimicrobials: determination and transferability of the resistance genes to other bacteria. Probiotic bacteria and starter cultures of Lactobacillus, Weissella and Bifidobacterium of African and European origins were studied and compared for their susceptibility to antimicrobials. The study included, for all isolates, determination of MICs (Minimal Inhibitory Concentration) for 24 antimicrobials, detection of resistance genes by PCR reactions using specific primers and sequencing of positive amplicons. The ability of Lb. reuteri from Africa to transfer the erythromycin resistance gene erm(B) to closely related bacteria was investigated by conjugation. Variations were observed and high levels of intrinsic resistance were found among the tested species. Positive amplicons were obtained for resistance genes encoding aminoglycoside (aph(3')-III, aadA, aadE) and tetracycline (tet(S)) from isolates from Europe and macrolide (erm(B)) from an isolate from Africa. However, only the erm(B) gene found in Lb. reuteri L4: 12002 from Africa contained a homologous sequence to previously published sequences. This gene could be transferred in vitro to enterococci. Higher prevalence of phenotypic resistance for aminoglycoside was found in isolates from Europe.200818063151
2693160.9998Prevalence, Antimicrobial Resistance and Toxin-Encoding Genes of Clostridioides difficile from Environmental Sources Contaminated by Feces. Clostridioides difficile (C. difficile) is the most common pathogen causing antibiotic-associated intestinal diseases in humans and some animal species, but it can also be present in various environments outside hospitals. Thus, the objective of this study was to investigate the presence and the characteristics of toxin-encoding genes and antimicrobial resistance of C. difficile isolates from different environmental sources. C. difficile was found in 32 out of 81 samples (39.50%) after selective enrichment of spore-forming bacteria and in 45 samples (55.56%) using a TaqMan-based qPCR assay. A total of 169 C. difficile isolates were recovered from those 32 C. difficile-positive environmental samples. The majority of environmental C. difficile isolates were toxigenic, with many (88.75%) positive for tcdA and tcdB. Seventy-four isolates (43.78%) were positive for binary toxins, cdtA and cdtB, and 19 isolates were non-toxigenic. All the environmental C. difficile isolates were susceptible to vancomycin and metronidazole, and most isolates were resistant to ciprofloxacin (66.86%) and clindamycin (46.15%), followed by moxifloxacin (13.02%) and tetracycline (4.73%). Seventy-five isolates (44.38%) showed resistance to at least two of the tested antimicrobials. C. difficile strains are commonly present in various environmental sources contaminated by feces and could be a potential source of community-associated C. difficile infections.202336671363
2906170.9998The mef(A) gene predominates among seven macrolide resistance genes identified in gram-negative strains representing 13 genera, isolated from healthy Portuguese children. Of the 176 randomly selected, commensal, gram-negative bacteria isolated from healthy children with low exposure to antibiotics, 138 (78%) carried one or more of the seven macrolide resistance genes tested in this study. These isolates included 79 (91%) isolates from the oral cavity and 59 (66%) isolates from urine samples. The mef(A) gene, coding for an efflux protein, was found in 73 isolates (41%) and was the most frequently carried gene. The mef(A) gene could be transferred from the donors into a gram-positive E. faecalis recipient and a gram-negative Escherichia coli recipient. The erm(B) gene transferred and was maintained in the E. coli transconjugants but was found in 0 to 100% of the E. faecalis transconjugants tested, while the other five genes could be transferred only into the E. coli recipient. The individual macrolide resistance genes were identified in 3 to 12 new genera. Eight (10%) of the oral isolates and 30 (34%) of the urine isolates for which the MICs were 2 to >500 microg of erythromycin per ml did not hybridize with any of the seven genes and may carry novel macrolide resistance genes.200415328110
2922180.9998Tetracycline-resistance genes in gram-negative isolates from estuarine waters. AIMS: To investigate the diversity and dissemination of tetracycline resistance genes in isolates from estuarine waters. METHODS AND RESULTS: Forty-two out of 164 multi-resistant isolates previously obtained were resistant or less-susceptible to tetracycline, as evaluated by the disc diffusion method. Minimal inhibitory concentration for resistant bacteria ranged from 16 to 256 mg l(-1). Screening of tet genes by polymerase chain reaction showed that 88% of the isolates carried at least one of the genes tested, namely tet(A) (present in 13 isolates), tet(B) (present in 13 isolates), tet(C) (present in 3 isolates), tet(D) (present in 1 isolate), tet(E) (present in 6 isolates) and tet(M) (present in 1 isolate). One isolate carried tet(A) and tet(M). To our knowledge, this study presents the first description of a tet(D) gene in Morganella morganii. Hybridization revealed that tet genes were plasmid-located in 31% of the isolates. Those isolates were included as donors in conjugation experiments and 38% transferred tetracycline resistance. CONCLUSIONS: A considerable diversity of tet genes was detected in the estuary. Frequently, these genes were associated with plasmids and could be transferred to Escherichia coli. SIGNIFICANCE AND IMPACT OF THE STUDY: The results presented provide further evidence of the role played by estuarine reservoirs in antibiotic resistance maintenance and dissemination.200819120920
2907190.9998Prevalence of tetracycline resistance genes and identification of tet(M) in clinical isolates of Escherichia coli from sick ducks in China. Tetracycline resistance is one of the most frequently encountered resistance properties in bacteria of animal origin. The aim of the present study was to investigate the prevalence and diversity of tetracycline resistance (tet) genes among Escherichia coli clinical isolates from diseased ducks in China and to report the identification and sequencing of the tet(M) gene. The susceptibility of 85 Escherichia coli strains to tetracyclines was determined by broth microdilution, and the presence of tet genes was investigated by multiplex PCR. All of the 85 isolates were fully resistant to both oxytetracycline and tetracycline, and 76.5 % were resistant to doxycycline. Seventy-seven of the isolates (90.6 %) encoded multiple tet genes, with 17.6, 38.8 and 34.1 % encoding two, three and four tet genes, respectively, and only 7.1 % encoded a single tet(A) gene. The MICs of oxytetracycline and tetracycline for all isolates ranged from 16 to ≥128 µg ml(-1) with a MIC90 of >128 µg ml(-1), regardless of the type or number of tet genes encoded. Isolates containing tet(M) commonly had more than one tet gene per strain. The doxycycline resistance rate in the tet(M)-positive isolates was significantly higher than in the tet(M)-negative isolates (P<0.05). A full-length tet(M) gene, including the promoter region, was obtained by PCR in seven of the 41 tet(M)-positive isolates and was sequenced and cloned. The cloned tet(M) gene conferred resistance to tetracyclines in the recombinant Escherichia coli host strain. These results revealed that, in these isolates, the prevalence of multiple tet genes was strikingly high and that tet(M) played a role in doxycycline resistance.201323475906