# | Rank | Similarity | Title + Abs. | Year | PMID |
|---|---|---|---|---|---|
| 0 | 1 | 2 | 3 | 4 | 5 |
| 3608 | 0 | 1.0000 | Natural antibiotic resistance of bacteria isolated from larvae of the oil fly, Helaeomyia petrolei. Helaeomyia petrolei (oil fly) larvae inhabit the asphalt seeps of Rancho La Brea in Los Angeles, Calif. The culturable microbial gut contents of larvae collected from the viscous oil were recently examined, and the majority (9 of 14) of the strains were identified as Providencia spp. Subsequently, 12 of the bacterial strains isolated were tested for their resistance or sensitivity to 23 commonly used antibiotics. All nine strains classified as Providencia rettgeri exhibited dramatic resistance to tetracycline, vancomycin, bacitracin, erythromycin, novobiocin, polymyxin, colistin, and nitrofurantoin. Eight of nine Providencia strains showed resistance to spectinomycin, six of nine showed resistance to chloramphenicol, and five of nine showed resistance to neomycin. All 12 isolates were sensitive to nalidixic acid, streptomycin, norfloxacin, aztreonam, cipericillin, pipericillin, and cefotaxime, and all but OF008 (Morganella morganii) were sensitive to ampicillin and cefoxitin. The oil fly bacteria were not resistant to multiple antibiotics due to an elevated mutation rate. For each bacterium, the number of resistant mutants per 10(8) cells was determined separately on rifampin, nalidixic acid, and spectinomycin. In each case, the average frequencies of resistant colonies were at least 50-fold lower than those established for known mutator strain ECOR 48. In addition, the oil fly bacteria do not appear to excrete antimicrobial agents. When tested, none of the oil fly bacteria produced detectable zones of inhibition on Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus, or Candida albicans cultures. Furthermore, the resistance properties of oil fly bacteria extended to organic solvents as well as antibiotics. When pre-exposed to 20 microg of tetracycline per ml, seven of nine oil fly bacteria tolerated overlays of 100% cyclohexane, six of nine tolerated 10% xylene, benzene, or toluene (10:90 in cyclohexane), and three of nine (OF007, OF010, and OF011) tolerated overlays of 50% xylene-50% cyclohexane. The observed correlation between antibiotic resistance and organic solvent tolerance is likely explained by an active efflux pump that is maintained in oil fly bacteria by the constant selective pressure of La Brea's solvent-rich environment. We suggest that the oil fly bacteria and their genes for solvent tolerance may provide a microbial reservoir of antibiotic resistance genes. | 2000 | 11055901 |
| 5546 | 1 | 0.9992 | Antibiotic resistance and Caco-2 cell invasion of Pseudomonas aeruginosa isolates from farm environments and retail products. The potential pathogenicity of Pseudomonas aeruginosa isolates from food animals, retail meat products, and food processing environments was evaluated by determining their antibiotic resistance profiles and invasiveness into human intestinal Caco-2 cell. In general, the genomically diversified isolates of P. aeruginosa were resistant to beta-lactams (ampicillin, amoxicillin-clavulanic acid, cefoxitin, ceftiofur, and cephalothin), chloramphenicol, tetracycline, kanamycin, nalidixic acid, and sulfamethoxazole-trimethoprim. Acquisition of any other antibiotic resistance genes, such as class 1 integrons and other beta-lactamase genes, was not found in the tested isolates. The expression of OprM membrane protein, which is associated with a multidrug efflux system, played a major role in their antibiotic resistance. Single mutation in the GyrA to confer resistance to nalidixic acids was also found in the tested isolates, indicating that these factors could synergistically affect the resistance of the P. aeruginosa isolates. The number of bacteria invading into the Caco-2 cells was 2.5 log(10) CFU/ml on average. Therefore, the public health concern of P. aeruginosa could be relevant since its occurrence in food animals could cross contaminate the retail meat products during food handling and processing. | 2007 | 17289197 |
| 5763 | 2 | 0.9991 | Development of in vitro resistance to fluoroquinolones in Pseudomonas aeruginosa. Fluoroquinolone resistance in Pseudomonas aeruginosa typically arises through site-specific mutations and overexpression of efflux pumps. In this study, we investigated the dynamics of different resistance mechanisms in P. aeruginosa populations that have evolved under fluoroquinolone pressure, as well as the interactions between these mechanisms in evolutionary trajectories. Bacteria of strain ATCC27853 were selected under different concentrations of ciprofloxacin and levofloxacin for six parallel lineages, followed by amplification of four target genes in the quinolone-resistance determining region (QRDR) and Sanger sequencing to identify the mutations. The expression of four efflux pump proteins was evaluated by real-time polymerase chain reaction using the relative quantitation method, with the ATCC27853 strain used as a control. We found that ciprofloxacin killed P. aeruginosa sooner than did levofloxacin. Further, we identified five different mutations in three subunits of QRDRs, with gyrA as the main mutated gene associated with conferring fluoroquinolone resistance. Additionally, we found a larger number of mutations appearing at 2 mg/L and 4 mg/L of ciprofloxacin and levofloxacin, respectively. Moreover, we identified the main efflux pump being expressed as MexCD-OprJ, with initial overexpression observed at 0.25 mg/L and 0.5 mg/L of ciprofloxacin and levofloxacin, respectively. These results demonstrated gyrA(83) mutation and MexCD-OprJ overexpression as the primary mechanism conferring ciprofloxacin and levofloxacin resistance in P. aeruginosa. In addition, we also show that ciprofloxacin exhibited a stronger ability to kill the bacteria while potentially rendering it more susceptible to resistance. | 2020 | 32758289 |
| 3574 | 3 | 0.9991 | Antibiotic resistances of starter and probiotic strains of lactic acid bacteria. The antibiotic resistances of 45 lactic acid bacteria strains belonging to the genera Lactobacillus, Streptococcus, Lactococcus, Pediococcus, and Leuconostoc were investigated. The objective was to determine antibiotic resistances and to verify these at the genetic level, as is currently suggested by the European "qualified presumption of safety" safety evaluation system for industrial starter strains. In addition, we sought to pinpoint possible problems in resistance determinations. Primers were used to PCR amplify genes involved in beta-lactam antibiotic, chloramphenicol, tetracycline, and erythromycin resistance. The presence of ribosomal protection protein genes and the ermB gene was also determined by using a gene probe. Generally, the incidences of erythromycin, chloramphenicol, tetracycline, or beta-lactam resistances in this study were low (<7%). In contrast, aminoglycoside (gentamicin and streptomycin) and ciprofloxacin resistances were higher than 70%, indicating that these may constitute intrinsic resistances. The genetic basis for ciprofloxacin resistance could not be verified, since no mutations typical of quinolone resistances were detected in the quinolone determining regions of the parC and gyrA genes. Some starter strains showed low-level ampicillin, penicillin, chloramphenicol, and tetracycline resistances, but no known resistance genes could be detected. Although some strains possessed the cat gene, none of these were phenotypically resistant to chloramphenicol. Using reverse transcription-PCR, these cat genes were shown to be silent under both inducing and noninducing conditions. Only Lactobacillus salivarius BFE 7441 possessed an ermB gene, which was encoded on the chromosome and which could not be transferred in filter-mating experiments. This study clearly demonstrates problems encountered with resistance testing, in that the breakpoint values are often inadequately identified, resistance genes may be present but silent, and the genetic basis and associated resistance mechanisms toward some antibiotics are still unknown. | 2007 | 17122388 |
| 2061 | 4 | 0.9991 | Resistance carrying plasmid in a traumatic wound. OBJECTIVE: To isolate and identify antibiotic-resistant bacteria from the exudate of a complex wound and determine if antibiotic resistance genes are chromosomal or plasmid borne. METHOD: Antibiotic resistant bacteria from wound exudate of a single clinical sample were selected on agar media with ampicillin. A single colony was further screened for resistance to kanamycin by antibiotic-supplemented agar and to other antibiotics by an automated Phoenix instrument. Identification of the isolate was carried out by biochemical profiling and by 16S rDNA analysis. RESULTS: Approximately 51% of total bacteria in the wound exudate with identical colony morphotype were resistant to 100 microg/ml of ampicillin. A single colony from this population also demonstrated resistance to 50 microg/ml of kanamycin on kanamycin-supplemented agar. Further antimicrobial sensitivity testing by the Phoenix instrument indicated resistance to inhibitory concentrations of amoxicillin-clavulanate, ampicillin-sulbactam, cefazolin, gentamicin, nitrofurantoin, tobramycin, and trimethoprim-sulfamethoxazole. Biochemical and 16S rDNA analysis identified this bacterial isolate as a member of genus Enterobacter. A plasmid preparation from this isolate successfully transferred ampicillin and kanamycin resistance to E. coli competent cells. E. coli transformants displayed two resistance phenotypes and the plasmids from these transformants displayed two different restriction type patterns, with one correlating to ampicillin and kanamycin resistance and the other only to ampicillin resistance. CONCLUSION: A multiple antibiotic-resistant Enterobacter spp. from the wound fluid of a clinical sample was found to carry an antibiotic-resistant plasmid in a closely related species E. coli. The presence of antibiotic resistance plasmid in Enterobacteria that are part of the normal microbial flora of the human gut and skin could lead to the spread of resistance phenotype and emergence of antibiotic resistant pathogens. This study suggests normal human microbial fl ora could be a potential reservoir for resistance genes. | 2010 | 20616773 |
| 5996 | 5 | 0.9991 | Molecular characterization of intrinsic and acquired antibiotic resistance in lactic acid bacteria and bifidobacteria. The minimum inhibitory concentrations (MICs) of 6 different antibiotics (chloramphenicol, clindamycin, erythromycin, streptomycin, tetracycline and vancomycin) were determined for 143 strains of lactic acid bacteria and bifidobacteria using the Etest. Different MICs were found for different species and strains. Based on the distribution of these MIC values, most of the strains were either susceptible or intrinsically resistant to these antibiotics. However, the MIC range of some of these antibiotics showed a bimodal distribution, which suggested that some of the tested strains possess acquired antibiotic resistance. Screening for resistance genes was performed by PCR using specific primers, or using a DNA microarray with around 300 nucleotide probes representing 7 classes of antibiotic resistance genes. The genes identified encoded resistance to tetracycline [tet(M), tet(W), tet(O) and tet(O/W)], erythromycin and clindamycin [erm(B)] and streptomycin [aph(E) and sat(3)]. Internal portions of some of these determinants were sequenced and found to be identical to genes described in other bacteria. All resistance determinants were located on the bacterial chromosome, except for tet(M), which was identified on plasmids in Lactococcus lactis. The contribution of intrinsic multidrug transporters to the antibiotic resistance was investigated by cloning and measuring the expression of Bifidobacterium breve genes in L. lactis. | 2008 | 17957105 |
| 5848 | 6 | 0.9990 | Plasmid and chromosomal basis of tolerance to cadmium and resistance to antibiotics in normal bovine duodenal bacterial flora. Cadmium (Cd) tolerance and antibiotic resistance was studied in duodenal flora of 20 normal bovine samples. Twelve bacterial isolates (5 Staphylococcus spp, 4 Enterococcus faecalis, 2 Bacillus spp, and a Pseudomonas sp) were grown in Luria broth containing 0.05 to 0.8 mM of cadmium chloride (CdCl). All isolates displayed multiple antibiotic resistance, with 2 Enterococcus strains and Pseudomonas pickettii demonstrating resistance to 12/17 antibiotics tested. With the exception of Staphylococcus sp, all contained plasmid DNA. Curing to remove plasmid DNA determined if Cd tolerance and/or antibiotic resistance was plasmid or chromosomally mediated. None of the bacteria became sensitive to CdCl after curing, suggesting that tolerance was not plasmid-mediated. Six bacteria became sensitive to antibiotics after curing indicating that antibiotic2 resistance was plasmid mediated. Two of these bacteria became sensitive to multiple antibiotics; a Staphylococcus sp became sensitive to ampicillin, ceftiofur and cephalothin, and a Enterococcus strain became sensitive to neomycin, oxacillin, and tiamulin. All of the isolates were probed for the presence of known Cd-resistance genes (cadA, cadC, and cadD). DNA-DNA hybridization revealed cadA- and cadC-related sequences in chromosomal DNA of a Staphylococcus sp, an Enterococcus strain, and in plasmid DNA of another Staphylococcus sp. No cadD-related sequences were detected in any of the 12 isolates even under reduced stringency of hybridization. | 2001 | 11383651 |
| 5959 | 7 | 0.9990 | High incidence of multiple antibiotic resistant cells in cultures of in enterohemorrhagic Escherichia coli O157:H7. The spontaneous incidence of chloramphenicol (Cam) resistant mutant bacteria is at least ten-fold higher in cultures of enterohemorrhagic Escherichia coli O157:H7 strain EDL933 than in E. coli K-12. It is at least 100-fold higher in the dam (DNA adenine methyltransferase) derivative of EDL933, compared to the dam strain of E. coli K-12, thereby preventing the use of Cam resistance as a marker in gene replacement technology. Genome sequencing of Cam-resistant isolates of EDL933 and its dam derivatives showed that the marR (multiple antibiotic resistance) gene was mutated in every case but not in the Cam-sensitive parental strains. As expected from mutation in the marR gene, the Cam-resistant bacteria were also found to be resistant to tetracycline and nalidixic acid. The marR gene in strain EDL933 is annotated as a shorter open reading frame than that in E. coli K-12 but the longer marR(+) open reading frame was more efficient at complementing the marR antibiotic-resistance phenotype of strain EDL933. Beta-lactamase-tolerant derivatives were present at frequencies 10-100 times greater in cultures of marR derivatives of strain EDL933 than the parent strain. Spontaneous mutation frequency to rifampicin, spectinomycin and streptomycin resistance was the same in E. coli O157:H7 and E. coli K-12 strains. | 2014 | 24361397 |
| 3646 | 8 | 0.9990 | Epibiotic Bacteria Isolated from the Non-Indigenous Species Codium fragile ssp. fragile: Identification, Characterization, and Biotechnological Potential. Due to their richness in organic substances and nutrients, seaweed (macroalgae) harbor a large number of epiphytic bacteria on their surfaces. These bacteria interact with their host in multiple complex ways, in particular, by producing chemical compounds. The released metabolites may have biological properties beneficial for applications in both industry and medicine. In this study, we assess the diversity of culturable bacterial community of the invasive alga Codium fragile ssp. fragile with the aim to identify key groups within this epiphytic community. Seaweed samples were collected from the Northern Tunisian coast. A total of fifty bacteria were isolated in pure culture. These bacterial strains were identified by amplification of the ribosomal intergenic transcribed spacer between the 16S and the 23S rRNA genes (ITS-PCR) and by 16S rRNA sequencing. Antimicrobial activity, biochemical, and antibiotic resistance profile characterization were determined for the isolates. Isolated strains were tested for their antimicrobial potential against human and fish bacterial pathogens and the yeast Candida albicans, using the in vitro drop method. About 37% of isolated strains possess antibacterial activity with a variable antimicrobial spectrum. Ba1 (closely related to Pseudoalteromonas spiralis), Ba12 (closely related to Enterococcus faecium), and Bw4 (closely related to Pseudoalteromonas sp.) exhibited strong antimicrobial activity against E. coli. The isolated strain Ba4, closely related to Serratia marcescens, demonstrated the most potent activity against pathogens. The susceptibility of these strains to 12 commonly used antibiotics was investigated. Majority of the isolates were resistant to oxacillin, cefoxitin, tobramycin, and nitrofurantoin. Ba7 and Ba10, closely related to the Vibrio anguillarum strains, had the highest multidrug resistance profiles. The enzymes most commonly produced by the isolated strains were amylase, lecithinase, and agarase. Moreover, nine isolates produced disintegration zones around their colonies on agar plates with agarolitic index, ranging from 0.60 to 2.38. This investigation highlighted that Codium fragile ssp. fragile possesses an important diversity of epiphytic bacteria on its surface that could be cultivated in high biomass and may be considered for biotechnological application and as sources of antimicrobial drugs. | 2024 | 39338477 |
| 3588 | 9 | 0.9990 | Metal and antibiotic resistance of bacteria isolated from the Baltic Sea. The resistance of 49 strains of bacteria isolated from surface Baltic Sea waters to 11 antibiotics was analyzed and the resistance of selected strains to three metal ions (Ni2+, Mn2+, Zn2+) was tested. Most isolates belonged to Gammaproteobacteria (78%), while Alphaproteobacteria (8%), Actinobacteria (10%), and Bacteroidetes (4%) were less abundant. Even though previous reports suggested relationships between resistance and the presence of plasmids or the ability to produce pigments, no compelling evidence for such relationships was obtained for the strains isolated in this work. In particular, strains resistant to multiple antibiotics did not carry plasmids more frequently than sensitive strains. A relation between resistance and the four aminoglycosides tested (gentamycin, kanamycin, neomycin, and streptomycin), but not to spectinomycin, was demonstrated. This observation is of interest given that spectinomycin is not always classified as an aminoglycoside because it lacks a traditional sugar moiety. Statistical analysis indicated relationships between resistance to some antibiotics (ampicillin and erythromycin, chloramphenicol and erythromycin, chloramphenicol and tetracycline, erythromycin and tetracycline), suggesting the linkage of resistance genes for antibiotics belonging to different classes. The effects of NiSO4, ZnCl2 and MnCl2 on various media suggested that the composition of Marine Broth might result in low concentrations of Mn2+ due to chemical interactions that potentially lead to precipitation. | 2012 | 23847817 |
| 5498 | 10 | 0.9990 | The prevalence of multidrug resistance in Staphylococcus hominis isolated from clinical materials. The treatment of infections caused by Staphylococcus hominis remains a challenge, mainly due to the increasing resistance of these bacteria to antibiotics. The aim of the study was to determine antibiotic resistance in 62 strains S. hominis isolated from clinical materials, and to identify the molecular basis of resistance to antibiotics. Forty-six strains were both methicillin-resistant and harbored the mecA gene. Twenty-three of these strains had mec complex A and ccr complex AB1. Such a combination of the mec and ccr complexes does not correspond to any cassettes that have been demonstrated so far. However, over 80% of the tested strains were multidrug-resistant, of which as many as 12 were resistant to at least seven antibiotics. More than a half of strains harbored the tetK, acc(6')-Ie aph(2''), and ant(4')-I genes. erm(C) was the most common resistant gene to antibiotics from the MLS group. Two strains had as many as five antibiotic resistance genes from the tested groups (erm(C), msr(A), msr(B), mph(C), lnu(A)). The presence of the vga gene encoding resistance to streptogramins A was detected in one strain. All of strains were sensitive to vancomycin. However, 11 of them had reduced sensitivity to this antibiotic and eight of them were characterized by a heterogeneous resistance profile to this antibiotic. Our results clearly shows increasing threat of S. hominis caused by their multi-resistance. Moreover, these bacteria can constitute a reservoir of resistance genes for more pathogenic bacteria. | 2025 | 39747570 |
| 5981 | 11 | 0.9990 | Alterations in the DNA topoisomerase IV grlA gene responsible for quinolone resistance in Staphylococcus aureus. A 4.2-kb DNA fragment conferring quinolone resistance was cloned from a quinolone-resistant clinical isolate of Staphylococcus aureus and was shown to possess a part of the grlB gene and a mutated grlA gene. S-80-->F and E-84-->K mutations in the grlA gene product were responsible for the quinolone resistance. The mutated grlA genes responsible for quinolone resistance were dominant over the wild-type allele, irrespective of gene dosage in a transformation experiment with the grlA gene alone. However, dominance by mutated grlA genes depended on gene dosage when bacteria were transformed with the grlA and grlB genes in combination. Quinolone-resistant gyrA mutants were easily isolated from a strain, S. aureus RN4220, carrying a plasmid with the mutated grlA gene, though this was not the case for other S. aureus strains lacking the plasmid. The elimination of this plasmid from such quinolone-resistant gyrA mutants resulted in marked increases in quinolone susceptibility. These results suggest that both DNA gyrase and DNA topoisomerase IV may be targets of quinolones and that the quinolone susceptibility of organisms may be determined by which of these enzymes is most quinolone sensitive. | 1996 | 8723458 |
| 5528 | 12 | 0.9990 | Bottled mineral water as a potential source of antibiotic resistant bacteria. The antibiotic resistance phenotypes of the cultivable bacteria present in nine batches of two Portuguese and one French brands of commercially available mineral waters were examined. Most of the 238 isolates recovered on R2A, Pseudomonas Isolation agar or on these culture media supplemented with amoxicillin or ciprofloxacin, were identified (based on 16S rRNA gene sequence analysis) as Proteobacteria of the divisions Beta, Gamma and Alpha. Bacteria resistant to more than three distinct classes of antibiotics were detected in all the batches of the three water brands in counts up to 10² CFU/ml. In the whole set of isolates, it was observed resistance against all the 22 antimicrobials tested (ATB, bioMérieux and disc diffusion), with most of the bacteria showing resistance to three or more classes of antibiotics. Bacteria with the highest multi-resistance indices were members of the genera Variovorax, Bosea, Ralstonia, Curvibacter, Afipia and Pedobacter. Some of these bacteria are related with confirmed or suspected nosocomial agents. Presumable acquired resistance may be suggested by the observation of bacteria taxonomically related but isolated from different brands, exhibiting distinct antibiotic resistance profiles. Bottled mineral water was confirmed as a possible source of antibiotic resistant bacteria, with the potential to be transmitted to humans. | 2012 | 22534119 |
| 5901 | 13 | 0.9990 | Identification and characterization of vancomycin-resistant Enterococcus species frequently isolated from laboratory mice. To determine the prevalence of drug resistant bacteria colonizing laboratory mice, we isolated and characterized vancomycin-resistant Enterococcus species (VRE) from commercially available mice. A total of 24 VRE isolates were obtained from 19 of 21 mouse strains supplied by 4 commercial breeding companies. Of these, 19 isolates of E. gallinarum and 5 isolates of E. casseliflavus possessing the vanC1 and vanC2/3 genes intrinsically, exhibited intermediate resistance to vancomycin respectively. In addition, these isolates also exhibited diverse resistant patterns to erythromycin, tetracycline, and ciprofloxacin, whereas the use of antibiotics had not been undertaken in mouse strains tested in this study. Although 6 virulence-associated genes (ace, asa, cylA, efaA, esp, and gelE) and secretion of gelatinase and hemolysin were not detected in all isolates, 23 of 24 isolates including the isolates of E. casselifalvus secreted ATP into culture supernatants. Since secretion of ATP by bacteria resident in the intestinal tract modulates the local immune responses, the prevalence of ATP-secreting VRE in mice therefore needs to be considered in animal experiments that alter the gut microflora by use of antibiotics. | 2014 | 25077759 |
| 5932 | 14 | 0.9990 | Detection of the florfenicol resistance gene floR in Chryseobacterium isolates from rainbow trout. Exception to the general rule? Bacteria from the family Flavobacteriaceae often show low susceptibility to antibiotics. With the exception of two Chryseobacterium spp. isolates that were positive for the florfenicol resistance gene floR, no clinical resistance genes were identified by microarray in 36 Flavobacteriaceae isolates from salmonid fish that could grow in ≥ 4 mg/L florfenicol. Whole genome sequence analysis of the floR positive isolates revealed the presence of a region that contained the antimicrobial resistance genes floR, a tet(X) tetracycline resistance gene, a streptothricin resistance gene and a chloramphenicol acetyltransferase gene. In silico analysis of 377 published genomes for Flavobacteriaceae isolates from a range of sources confirmed that well-characterised resistance gene cassettes were not widely distributed in bacteria from this group. Efflux pump-mediated decreased susceptibility to a range of antimicrobials was confirmed in both floR positive isolates using an efflux pump inhibitor (phenylalanine-arginine β-naphthylamide) assay. The floR isolates possessed putative virulence factors, including production of siderophores and haemolysins, and were mildly pathogenic in rainbow trout. Results support the suggestion that, despite the detection of floR, susceptibility to antimicrobials in Flavobacteriaceae is mostly mediated via intrinsic mechanisms rather than the horizontally acquired resistance genes more normally associated with Gram-negative bacterial pathogens such as Enterobacteriaceae. | 2017 | 28199699 |
| 6064 | 15 | 0.9990 | Evaluation of marine bacteriocinogenic enterococci strains with inhibitory activity against fish-pathogenic Gram-negative bacteria. Use of lactic acid bacteria (LAB) as probiotics may provide an alternative to the use of antibiotics in aquaculture. LAB strains isolated from wild fish viscera and skin were evaluated for bacteriocin production and safety aspects (lack of antibiotic resistance, production of virulence factors). 16S rRNA gene sequences revealed the presence of Enterococcus faecium (13 isolates) and Lactococcus lactis (3 isolates) from fish samples. Pulsed-field gel electrophoresis analyses of the 13 enterococci isolates showed that they were all clustered, with greater than 95% similarity. However, RAPD analysis revealed significant molecular diversity between enterococci strains. Six enterococci strains were chosen and evaluated for their antibacterial activities. These strains produced a bacteriocin-like substance and exhibited a broad spectrum of inhibition against pathogenic bacteria isolated from diseased fish, including Streptococcus parauberis, Vagococcus spp., and Carnobacterium maltaromaticum, and in particular against the Gram-negative bacteria Flavobacterium frigidarium, Vibrio pectenicida, V. penaeicida, and Photobacterium damselae. The inhibition activity towards bacterial indicator strains was at a maximum when bacteria were grown at 37°C. However, bacteriocin production was observed at 15°C after 12 h of incubation. Only structural genes of enterocins A and B were detected by PCR in the 6 enterococci strains, suggesting the production of these enterocins. In addition, these strains did not harbor any virulence factors or any significant antibiotic resistance, and they tolerated bile. Our results suggest that enterococci are an important part of the bacterial flora of fish and that some strains have the potential to be used as probiotics. | 2016 | 26865233 |
| 4512 | 16 | 0.9990 | Resident microbiota of the gypsy moth midgut harbors antibiotic resistance determinants. Little is known about the significance of insects as environmental reservoirs of antibiotic-resistant bacteria. We characterized the antibiotic resistome of the microbial community in gypsy moth larval midguts by applying functional metagenomics to cultured isolates. The minimum inhibitory concentrations of 12 antibiotics were determined for 44 cultured isolates, and antibiotic resistance genes were selected from metagenomic libraries derived from DNA extracted from a pool of the isolates. Six unique clones were identified. Two were highly resistant to penicillin-type beta-lactams, two were moderately resistant to erythromycin, and two were moderately resistant to a range of antibiotics, including erythromycin, carbenicillin, and chloramphenicol. Sequence analysis predicted that the active genes encoded efflux pumps, a transcriptional activator of efflux pump protein expression, and an extended-spectrum class A beta-lactamase. Insect guts are a reservoir of antibiotic resistance genes with the potential for dissemination. | 2009 | 19206998 |
| 2883 | 17 | 0.9990 | In vitro susceptibility of Vibrio spp. isolated from the environment. Bacteria of the genus Vibrio include harmless aquatic strains as well as strains capable of causing epidemics of cholera and human intestinal diseases. Some of these species may show resistance to different antibiotics including cefotaxime, tetracycline and chloramphenicol. The susceptibility to different antibiotics was tested using 40 Vibrio alginolyticus, eight V. parahaemolyticus and six V. vulnificus strains isolated in the coastal waters of Northern Sardinia (Italy). The frequency of resistance to beta-lactams was unexpectedly high. More than 80% of Vibrio isolates were resistant to ampicillin and 2.5% of V. alginolyticus were resistant to ceftazidime and cefotetan. Forty percent of V. alginolyticus and three V. vulnificus isolates gave a positive nitrocefin test. PCR was also performed using selected primers chosen for having common sequences of bla(TEM) and bla(SHV) genes. | 2001 | 11337229 |
| 5904 | 18 | 0.9990 | Antimicrobial susceptibilities of Lactobacillus, Pediococcus and Lactococcus human isolates and cultures intended for probiotic or nutritional use. OBJECTIVES: To determine MICs of 16 antimicrobials representing all major classes for 473 taxonomically well-characterized isolates of lactic acid bacteria (LAB) encompassing the genera Lactobacillus, Pediococcus and Lactococcus. To propose tentative epidemiological cut-off (ECOFF) values for recognizing intrinsic and acquired antimicrobial resistances in numerically dominant species. METHODS: On the basis of depositors' information, LAB were grouped in categories of probiotic, nutritional, probiotic or nutritional research, human and animal isolates and tested for their antibiotic susceptibilities by broth microdilution using LAB susceptibility test medium (LSM). Tentative ECOFFs were defined according to the recommendations of the European Committee on Antimicrobial Susceptibility Testing. Isolates showing acquired antimicrobial resistance(s) were selected for PCR-based detection of resistance gene(s) and in vitro conjugative transfer experiments. RESULTS: Tentative ECOFF values of 13 antibiotics were determined for up to 12 LAB species. Generally, LAB were susceptible to penicillin, ampicillin, ampicillin/sulbactam, quinupristin/dalfopristin, chloramphenicol and linezolid. LAB exhibited broad or partly species-dependent MIC profiles of trimethoprim, trimethoprim/sulfamethoxazole, vancomycin, teicoplanin and fusidic acid. Three probiotic Lactobacillus strains were highly resistant to streptomycin. Although erythromycin, clindamycin and oxytetracycline possessed high antimicrobial activities, 17 Lactobacillus isolates were resistant to one or more of these antibiotics. Eight of them, including six probiotic and nutritional cultures, possessed erm(B) and/or tet(W), tet(M) or unidentified members of the tet(M) group. In vitro intra- and interspecies filter-mating experiments failed to show transfer of resistance determinants. CONCLUSIONS: Finding of acquired resistance genes in isolates intended for probiotic or nutritional use highlights the importance of antimicrobial susceptibility testing in documenting the safety of commercial LAB. | 2007 | 17369278 |
| 3645 | 19 | 0.9990 | Inter-species competition of surface bacterial flora of pomegranate and their role in spoilage. The surface of fruits is heterogenous in term of its microenvironment hence dictate the kind of microflora that develops during storage. A better understanding of spoilage organisms would lead to better preservation methods. The pomegranate was chosen, since its sturdy and spoils slow at room temperature and is ideal for studying fruit spoilage in-situ. In the current study we isolated organisms from fruit surface and study the spoilage and competition amongst microbial species. Total 17 unique bacterial isolates from pomegranate were identified. The 16S rRNA gene identification placed them in 8 major genera (Acinetobacter, Micrococcus, Pantoea, Microbacterium, Strenotrophomonas, Bacillus, Staphylococcus and Exiguobacterium). Competition assay among isolate suggested that Exiguobacterium is dominant species followed by Micrococcus, Pantoea and Bacillus. The consortium of 3 different combinations (5 bacteria each) of isolated bacteria showed the spoilage phenotype on pomegranate. Except for 3 bacterial isolates, the rest of the isolates produced any one or multiple enzymes associated with the food spoilage (cellulase, amylase, lactase, pectinase and protease). The isolates were checked for the presence of genes associated with antibiotic resistance and 78.9% of the tested micro-organisms were blaTEM positive. Aminoglycoside resistance genes were present in 10% of the tested microbes. This study demonstrated interspecies competition amongst spoilage organisms. This understanding of surface flora of fruit would give better insights to preserve fruits. | 2023 | 37495862 |