Incidence of virulence determinants and antibiotic resistance in lactic acid bacteria isolated from food products. - Related Documents




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605701.0000Incidence of virulence determinants and antibiotic resistance in lactic acid bacteria isolated from food products. Background: Lactic acid bacteria (LAB) confer beneficial health effects in humans. However, the safety of these bacteria and their potential to spread resistance in the environment must be evaluated. Materials & methods: Fifty-three LAB were isolated from different food samples and assessed for the prevalence of virulence determinants and antibiotic resistance profile. Results: Multiple resistance was reported for Lactobacillus brevis MIM04, having revealed phenotypic resistance to vancomycin (MIC >128 μg/ml), ampicillin, cefotaxime, oxacillin and gentamicin. Virulence traits (cylA, gelE, esp and agg) were detected using specific primers. Enterococcus faecium CHE32, Lactobacillus plantarum CHE37 and E. faecium MLK68 lack virulence genes, possess antimicrobial activity and survive in low pH and bile salt conditions. Conclusion: Isolated LAB revealed probiotic properties.202235172602
590610.9997Antibiotic resistance of probiotic strains of lactic acid bacteria isolated from marketed foods and drugs. OBJECTIVE: To identify the antimicrobial resistance of commercial lactic acid bacteria present in microbial foods and drug additives by analyzing their isolated strains used for fermentation and probiotics. METHODS: Antimicrobial susceptibility of 41 screened isolates was tested with disc diffusion and E-test methods after species-level identification. Resistant strains were selected and examined for the presence of resistance genes by PCR. RESULTS: Distribution of resistance was found in different species. All isolates were susceptible to chloramphenicol, tetracycline, ampicillin, amoxicillin/clavulanic acid, cephalothin, and imipenem. In addition, isolates resistant to vancomycin, rifampicin, streptomycin, bacitracin, and erythromycin were detected, although the incidence of resistance to these antibiotics was relatively low. In contrast, most strains were resistant to ciprofloxacin, amikacin, trimethoprim/sulphamethoxazole, and gentamycin. The genes msrC, vanX, and dfrA were detected in strains of Enterococcus faecium, Lactobacillus plantarum, Streptococcus thermophilus, and Lactococcus lactis. CONCLUSION: Antibiotic resistance is present in different species of probiotic strains, which poses a threat to food safety. Evaluation of the safety of lactic acid bacteria for human consumption should be guided by established criteria, guidelines and regulations.200920163065
590020.9996Safety profiles of beneficial lactic acid bacteria isolated from dairy systems. This study aimed to assess the safety aspects of 15 lactic acid bacteria (LAB) strains previously isolated from a dairy environment with relation to their beneficial features. LAB strains were assessed using phenotypic methods according to their production of virulence factors at 25 °C and 37 °C, as well as by examining their potential resistance to 15 antibiotics. Polymerase chain reaction (PCR) was also used to identify the presence of 50 genes associated with virulence factors and antibiotic resistance in the strains. None of the strains presented hemolytic activity or the production of gelatinase, lipase, deoxyribonuclease, or the tested biogenic amines. Based on the disk diffusion assay, all strains were resistant to oxacillin and sulfa/trimethoprim. Further, some were resistant to gentamicin (14), clindamycin (11), vancomycin (9), rifampicin (8), erythromycin (5), tetracycline (4), ampicillin (2), and chloramphenicol (1); no strain was resistant to imipenem. Regarding virulence- and antibiotic-resistance-related genes, 19 out of 50 tested genes were present in some strains; there was a variable association of expression. Based on the obtained data, the isolates presented relatively safe characteristics and behavior, findings that should lead to further studies to assess their potential usage as beneficial cultures in the food industry.202031970700
590130.9996Identification 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.201425077759
243140.9996Bacteriocin production, antibiotic susceptibility and prevalence of haemolytic and gelatinase activity in faecal lactic acid bacteria isolated from healthy Ethiopian infants. The objective of this study was to characterise lactic acid bacteria (LAB) isolated from faecal samples of healthy Ethiopian infants, with emphasis on bacteriocin production and antibiotic susceptibility. One hundred fifty LAB were obtained from 28 healthy Ethiopian infants. The isolates belonged to Lactobacillus (81/150), Enterococcus (54/150) and Streptococcus (15/150) genera. Lactobacillus species were more abundant in the breast-fed infants while Enterococcus dominated the mixed-fed population. Bacteriocin-producing LAB species were isolated from eight of the infants. Many different bacteriocins were identified, including one new bacteriocin from Streptococcus salivarius, avicin A (class IIa) from Enterococcus avium, one class IIa bacteriocin from Enterococcus faecalis strains, one unknown bacteriocin from E. faecalis and two unknown bacteriocins from Lactobacillus fermentum strains and the two-peptide gassericin T from Lactobacillus gasseri isolate. Susceptibility tests performed for nine antibiotics suggest that some lactobacilli might have acquired resistance to erythromycin (3 %) and tetracycline (4 %) only. The streptococci were generally antibiotic sensitive except for penicillin, to which they showed intermediate resistance. All enterococci were susceptible to ampicillin while 13 % showed penicillin resistance. Only one E. faecalis isolate was vancomycin-resistant. Tetracycline (51 %) and erythromycin (26 %) resistance was prevalent among the enterococci, but multidrug resistance was confined to E. faecalis (47 %) and Enterococcus faecium (33 %). Screening of enterococcal virulence traits revealed that 2 % were β-haemolytic. The structural genes of cytolysin were detected in 28 % of the isolates in five enterococcal species, the majority being E. faecalis and Enterococcus raffinosus. This study shows that bacteriocin production and antibiotic resistance is a common trait of faecal LAB of Ethiopian infants while virulence factors occur at low levels.201323184155
243550.9996Genotypic and Technological Characterization of Lactic Acid Bacteria and Coagulase-Negative Staphylococci Isolated from Sucuk: A Preliminary Screening of Potential Starter Cultures. This study aimed to characterize lactic acid bacteria (LAB) and coagulase-negative staphylococci (CoNS) isolated from traditionally produced sucuk for their potential use in starter culture development and food safety applications in fermented meat products. A total of 145 isolates (95 LAB and 50 CoNS) were analyzed through genetic identification, phylogenetic analysis, and assessments of technological properties. Antagonistic activity against Listeria monocytogenes and Staphylococcus aureus was also evaluated, along with antibiotic sensitivity. Among LAB, Lactiplantibacillus plantarum was the most prevalent species (60 isolates), while Staphylococcus xylosus was the predominant CoNS species (24 isolates). The isolates exhibited diverse technological properties and varying levels of antagonistic activity against the tested pathogens. Antibiotic sensitivity tests indicated that 15 selected isolates were negative for antibiotic resistance genes. Overall, this comprehensive characterization provides valuable insights for the development of starter cultures and for enhancing food safety in fermented meat products.202541154032
590360.9996Screening of virulence determinants in Enterococcus faecium strains isolated from breast milk. In a previous study, the authors isolated lactic acid bacteria from breast milk of healthy mothers. Since some of the identified isolates belonged to the species Enterococcus faecium, the objective of this work was to evaluate their safety. The enterococcal strains were screened by polymerase chain reaction (PCR) and Southern hybridization for the presence of virulence determinants. The potential of the strains to acquire plasmids by conjugation was investigated by screening for genes involved in conjugation processes. Parallel, phenotypic assays were performed. Presence of genes conferring resistance to vancomycin was assessed by PCR. PCR amplifications and Southern hybridizations revealed that all the strains were clear of the majority of potential virulence determinants. None of the strains showed gelatinase activity, hemolysin production, or aggregation phenotype, and none carried the vanA or vanB genes. These findings suggest that milk of healthy mothers may be a source of avirulent E faecium isolates to the newborns.200515886339
590770.9996Antimicrobial susceptibility of starter culture bacteria used in Norwegian dairy products. Commercial starter culture bacteria are widely used in the production of dairy products and could represent a potential source for spread of genes encoding resistance to antimicrobial agents. To learn more about the antimicrobial susceptibility of starter culture bacteria used in Norwegian dairy products, a total of 189 isolates of lactic acid bacteria were examined for susceptibility to ampicillin, penicillin G, cephalothin, vancomycin, bacitracin, gentamicin, streptomycin, erythromycin, tetracycline, chloramphenicol, quinupristin/dalfopristin, ciprofloxacin, trimethoprim and sulphadiazine using Etest for MIC determination. Most of the isolates (140) originated from 39 dairy products (yoghurt, sour cream, fermented milk and cheese), while 49 were isolated directly from nine commercial cultures. The bacteria belonged to the genera Lactobacillus, Lactococcus, Leuconostoc and Streptococcus. Only one of the 189 isolates was classified as resistant to an antimicrobial agent included in the study. This isolate, a lactobacillus, was classified as high level resistant to streptomycin. The remaining isolates were not classified as resistant to the antimicrobial agents included other than to those they are known to have a natural reduced susceptibility to. Thus, starter culture bacteria in Norwegian dairy products do not seem to represent a source for spread of genes encoding resistance to antimicrobial agents.200111482563
605680.9996Virulence, antibiotic resistance and biogenic amines of bacteriocinogenic lactococci and enterococci isolated from goat milk. The present study aimed to investigate the virulence, antibiotic resistance and biogenic amine production in bacteriocinogenic lactococci and enterococci isolated from goat milk in order to evaluate their safety. Twenty-nine bacteriocinogenic lactic acid bacteria (LAB: 11 Lactococcus spp., and 18 Enterococcus spp.) isolated from raw goat milk were selected and subjected to PCR to identify gelE, cylA, hyl, asa1, esp, efaA, ace, vanA, vanB, hdc1, hdc2, tdc and odc genes. The expression of virulence factors (gelatinase, hemolysis, lipase, DNAse, tyramine, histamine, putrescine) in different incubation temperatures was assessed by phenotypic methods, as well as the resistance to vancomycin, gentamicin, chloramphenicol, ampicillin and rifampicin (using Etest®). The tested isolates presented distinct combinations of virulence related genes, but not necessarily the expression of such factors. The relevance of identifying virulence-related genes in bacteriocinogenic LAB was highlighted, demanding for care in their usage as starter cultures or biopreservatives due to the possibility of horizontal gene transfer to other bacteria in food systems.201424960293
590990.9996Antibiotic susceptibility profiles of Lactobacillus reuteri and Lactobacillus fermentum. Lactobacillus reuteri and Lactobacillus fermentum, which are commonly used as food processing aids and probiotics, can potentially act as reservoirs of antibiotic resistance genes. Acquired resistance genes may be transferred via the food chain or in the gastrointestinal tract to pathogenic bacteria. Knowledge of the distributions of antibiotic MICs for a species is needed when using a phenotypic method to assess the presence of acquired resistance genes. In the present study, 56 L. reuteri and 56 L. fermentum strains that differed by source and spatial and temporal origin were assessed for antibiotic susceptibility using an Etest kit and a broth microdilution protocol. L. fermentum strains displayed a uniform distribution of MICs for all six antibiotics tested. L. reuteri strains had a bimodal distribution of MICs or a distribution with MICs above the test range for 7 of the 14 antibiotics tested. Genetic relatedness was observed among L. reuteri strains with high MICs for both ampicillin and tetracycline and among strains with high MICs for both erythromycin and clindamycin. Results obtained with the Etest and the broth microdilution method corresponded well with each other. Thus, further research may make it possible to define microbiological breakpoints for distinguishing between strains with and without acquired resistance genes.200717340877
2430100.9996Characterization of bacteriocinogenic Enterococcus isolates from wild and laboratory rabbits for the selection of autochthonous probiotic strains in Tunisia. AIM: The objective of this study was to characterize lactic acid bacteria (LAB) from rabbits to be used as potential autochthonous probiotic. METHODS AND RESULTS: Fifteen faecal samples were collected from wild and laboratory rabbits. One hundred and eight isolates were collected and tested for their inhibitory power against eight pathogenic bacteria. Among them, 43 Enterococcus isolates were able to inhibit at least one pathogen. Enterocine genes entA, entB and entP were detected in 14, 17 and 22 isolates, respectively. These isolates were tested for their antibiotic susceptibility and genes encoding virulence factors. Relevant phenotypes of antibiotic resistance were observed especially for ampicillin, vancomycin and linezolid. The following virulence genes were detected (number of positive isolates): hyl (5), esp (8), gelE (30), agg (2), ace (21), efa (6), CylL(L/s) (5), cob (26), cpd (32) and ccf (33). Five isolates were considered as safe and showed tolerance to both acid and bile salt. CONCLUSION: Bacteriocinogenic enterococci isolates from rabbits may show relevant resistance phenotypes and virulence factors. In addition, one Enterococcus durans isolate presents promising autochthonous probiotic candidate. SIGNIFICANCE AND IMPACT OF THE STUDY: This study reveals interesting properties for E. durans isolate and supports their utilization as autochthonous probiotic in rabbit husbandry.202133629433
2436110.9996Lactic Acid Bacteria as Biological Control of Staphylococcus aureus in Coalho Goat Cheese. The aim of this study is to investigate the bacterial population in coalho goat cheese produced in the semi-arid northeast region of Brazil, to analyse the antibiotic resistance profiles of the identified pathogenic bacteria, to detect the staphylococcal enterotoxin genes and to evaluate the addition of autochthonous lactic acid bacteria (LAB) with technofunctional properties for the control of Staphylococcus aureus growth. In the analysed samples, strains of Escherichia coli (N=11), Salmonella spp. (N=18), Listeria spp. (N=6) and S. aureus (N=9) were classified as multidrug resistant (MDR). The most commonly isolated pathogen from the studied coalho goat cheese was S. aureus. Its isolates were positive for the genes encoding enterotoxins A (sea), B (seb), C (sec) and D (sed). The autochthonous LAB with the potential to inhibit S. aureus were identified as Enterococcus faecium. These strains were selected for in vitro tests of protective, safety, technological and functional properties. In the coalho goat cheese food matrix, these selected autochthonous LAB were able to reduce the enterotoxigenic MDR S. aureus load by approx. 3 log units.201830510486
2433120.9996Confirmed low prevalence of Listeria mastitis in she-camel milk delivers a safe, alternative milk for human consumption. She-camel milk is an alternative solution for people allergic to milk; unfortunately, potential harmful bacteria have not been tested in she-camel milk. Listeria monocytogenes is one harmful bacterium that causes adverse health effects if chronically or acutely ingested by humans. The purpose of this study was to estimate the prevalence, characterize the phenotypic, genetic characterization, virulence factors, and antibiopotential harmful bacteria resistance profile of Listeria isolated from the milk of she-camel. Udder milk samples were collected from 100 she-camels and screened for mastitis using the California mastitis test (46 healthy female camels, 24 subclinical mastitic animals and 30 clinical mastitic animals). Samples were then examined for the presence of pathogenic Listeria spp; if located, the isolation of Listeria was completed using the International Organization for Standards technique to test for pathogenicity. The isolates were subjected to PCR assay for virulence-associated genes. Listeria spp. were isolated from 4% of samples and only 1.0% was confirmed as L. monocytogenes. The results of this study provide evidence for the low prevalence of intramammary Listeria infection; additionally, this study concludes she-camel milk in healthy camels milked and harvested in proper hygienic conditions may be used as alternative milk for human consumption.201424161878
2432130.9996Antimicrobial resistance, virulence characteristics and genotypes of Bacillus spp. from probiotic products of diverse origins. Spore-forming probiotic Bacillus spp. have received extensively increasing scientific and commercial interest, but raised the concerns in the potential risks and pathogenesis. In this study, 50 commercial probiotic products were collected from all over the country and Bacillus spp. isolated from products were evaluated for the safety on the aspects of hemolytic activity, contamination profiles, toxin genes, cytotoxicity, antimicrobial resistance, and genotyping. 34 probiotic products (68%) exhibited hemolysis, including 19 human probiotics, 9 animal probiotics, and 6 plant probiotics. 28 products (56%) contained other bacteria not labeled in the ingredients. 48 strains in Bacillus spp. including 17 B. subtilis group isolates, 28 B. cereus, and 3 other Bacillus spp. were isolated from human, food animal, and plant probiotic products. Detection rates of enterotoxin genes, nheABC and hblCDA, and cytotoxin cytK2 in 48 Bacillus spp. isolates were 58%, 31%, and 46%, respectively. Also, one isolate B. cereus 34b from an animal probiotic product was positive for ces, encoding cereulide. 28 of 48 Bacillus spp. isolates were cytotoxic. 19 of 28 B. cereus isolates maintained to exhibit hemolysis after heat treatment. All 48 Bacillus spp. isolates exhibited resistance to lincomycin, and 5 were resistant to tetracycline. The genotyping of commercial probiotic Bacillus spp. reported in this study showed that ces existed in B. cereus 34b with the specific sequence type (ST1066). These findings support the hypothesis that probiotic products were frequently contaminated and that some commercial probiotics consisted of Bacillus spp. may possess toxicity and antimicrobial resistance genes. Thus, the further efforts are needed in regarding the surveillance of virulence factors, toxins, and antibiotic resistance determinants in probiotic Bacillus spp.202133509502
5904140.9996Antimicrobial 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.200717369278
5782150.9996The Efficacy of Bacteriocins Against Biofilm-Producing Bacteria Causing Bovine Clinical Mastitis in Dairy Farms: A New Strategy. Using an alternative bio-product is one of the most promising ways to control bovine mastitis and avoid new intra-mammary infections. The aims of this study were to ascertain the prevalence of biofilm-forming bacteria responsible for causing clinical mastitis in dairy herds and to assess the effectiveness of bacteriocins, produced by Bacillus subtilis, in controlling the growth of these bacteria in the milk of animals. A total of 150 milk samples were collected from cows and buffalos suffering from mastitis and the etiological agents were isolated and identified by the VITEK-2-COMPACT-SYSTEM®. Additionally, the capability of the bacterial isolates to produce biofilms was determined. RT-PCR was used to detect enterotoxin-producing genes (sed and seb), resistance genes (mecA and blaZ), and biofilm-associated genes (icaA and fnbA) in the isolated bacteria. The susceptibility patterns of the bacterial isolates to bacteriocins were assessed using an agar well-diffusion assay. S. aureus was significantly more capable of producing biofilms than coagulase-negative Staphylococcus isolates. S. ubris was the strongest biofilm producer among the Streptococcus species. The sensitivity profiles of the Staphylococcus spp. (S. aureus and coagulase-negative Staphylococcus) and their biofilm producers to bacteriocins were significantly higher (100% and 90%, respectively) at the same concentration. Bacteriocins had a lethal effect on Staphylococci, Streptococci, and biofilm development at a dose of 250 µg/mL. In dairy farms, bacteriocins are a viable alternative treatment for the prevention and control of bovine clinical mastitis.202337256384
5905160.9995Characterization of Antibiotic Resistance Genes from Lactobacillus Isolated from Traditional Dairy Products. Lactobacilli are widely used as starter cultures or probiotics in yoghurt, cheese, beer, wine, pickles, preserved food, and silage. They are generally recognized as safe (GRAS). However, recent studies have shown that some lactic acid bacteria (LAB) strains carry antibiotic resistance genes and are resistant to antibiotics. Some of them may even transfer their intrinsic antibiotic resistance genes to other LAB or pathogens via horizontal gene transfer, thus threatening human health. A total of 33 Lactobacillus strains was isolated from fermented milk collected from different areas of China. We analyzed (1) their levels of antibiotic resistance using a standardized dilution method, (2) their antibiotic resistance gene profiles by polymerase chain reaction (PCR) using gene-specific primers, and (3) the transferability of some of the detected resistance markers by a filter mating assay. All Lactobacillus strains were found to be resistant to vancomycin, but susceptible to gentamicin, linezolid, neomycin, erythromycin, and clindamycin. Their susceptibilities to tetracycline, kanamycin, ciprofloxacin, streptomycin, quinupristin/dalfopristin, trimethoprim, ampicillin, rifampicin, and chloramphenicol was different. Results from our PCR analysis revealed 19 vancomycin, 10 ciprofloxacin, and 1 tetracycline-resistant bacteria that carried the van(X), van(E), gyr(A), and tet(M) genes, respectively. Finally, no transferal of the monitored antibiotic resistance genes was observed in the filter mating assay. Taken together, our study generated the antibiotic resistance profiles of some milk-originated lactobacilli isolates and preliminarily assessed their risk of transferring antibiotic gene to other bacteria. The study may provide important data concerning the safe use of LAB.201728182844
2441170.9995Phenotypic and molecular assessment of antimicrobial resistance profile of airborne Staphylococcus spp. isolated from flats in Kraków. Bacteria of the genus Staphylococcus were isolated from air sampled from living spaces in Kraków (Poland). In total, 55 strains belonging to the genus Staphylococcus were isolated from 45 sites, and 13 species of coagulase-negative staphylococci were identified. The species composition of studied airborne microbiota contains Staphylococcus species that are rarely infectious to humans. Most commonly isolated species comprised S. hominis and S. warneri. The disk-diffusion tests showed that the collected isolates were most frequently resistant to erythromycin. The PCR technique was employed to search for genes conferring the resistance in staphylococci to antibiotics from the group of macrolides, lincosamides and streptogramins. The analyzed Staphylococcus isolates possessed simultaneously 4 different resistance genes. The molecular analysis with the use of specific primers allowed to determine the most prevalent gene which is mphC, responsible for the resistance to macrolides and for the enzymatic inactivation of the drug by phosphotransferase. The second most often detected gene was msrA1, which confers the resistance of staphylococci to macrolides and is responsible for active pumping of antimicrobial particles out of bacterial cells.201728955110
5534180.9995Antibiotic resistance in faecal microbiota of Greek healthy infants. Increasing use of antibiotics for the treatment of infectious diseases and also for non-therapeutic reasons (agriculture, animal husbandry and aquaculture) has led to the increasing incidence of antibiotic resistance and the ineffectiveness of antimicrobial treatment. Commensal intestinal bacteria are very often exposed to the selective pressure of antimicrobial agents and may constitute a reservoir of antibiotic resistance determinants that can be transferred to pathogens. The present study aimed to investigate the antibiotic susceptibility profile and the presence of selected resistance genes in cocci isolated from the faecal microbiota of 35 healthy, full-term infants at 4, 30 and 90 days after delivery. A total of 148 gram-positive, catalase-negative cocci were isolated and tested for susceptibility to 12 different antibiotics by disk-diffusion technique. Multiplex PCR analysis was performed for the identification of Enterococcus spp. isolates and the simultaneous detection of vancomycin-resistance genes. PCR-based methodology was used also for identification of tetracycline and erythromycin resistance determinants. Identification results indicated E. faecalis as the predominant species (81 strains), followed by E. faecium, E. casseliflavus/E. flavescens and E. gallinarum. High prevalence of resistance to tetracycline (39.9%), erythromycin (35.1%), vancomycin (19.6%) and to nucleic acid synthesis inhibitors was detected. PCR data revealed 24 out of 52 erythromycin-resistant isolates carrying the ermB gene and 32 out of 59 tetracycline-resistant strains carrying tet genes, with tet(L) determinant being the most frequently detected. Only intrinsic vancomycin resistance (vanC1 and vanC2/C3) was reported among tested isolates. In conclusion, erythromycin and tetracycline acquired resistant traits are widespread among faecal cocci isolates from Greek, healthy infants under no apparent antimicrobial selective pressure.201021831766
5596190.9995Enterotoxigenicity and Antibiotic Resistance of Coagulase-Negative Staphylococci Isolated from Raw Buffalo and Cow Milk. Staphylococcal food poisoning is considered to be one of the most common foodborne illnesses worldwide. Because milk is rich in nutrients and its neutral pH, it leads to the growth of various bacteria. To date, the correlation between enterotoxigenic potential in Staphylococcus species and antimicrobial resistance (AMR), using bioinformatics analysis in buffalo and cow raw milk and the possible health risks from these bacteria, has not been examined in Egypt. A total of 42 Staphylococcus isolates representing 12 coagulase-positive staphylococci (Staphylococcus aureus and Staphylococcus intermedius) and 30 coagulase-negative staphylococci (Staphylococcus capitis, Staphylococcus xylosus, Staphylococcus carnosus, Staphylococcus saccharolyticus, and Staphylococcus auricularis) were isolated. An assay of the antimicrobial resistance phenotypes indicated low resistance against vancomycin (9.5%). The blaZ gene was associated with penicillin G and methicillin resistance and not with sulbactam + ampicillin. The presence of the gene ermB presented the correlation with erythromycin resistance and tetK with tetracycline resistance (correlation index: 0.57 and 0.49, respectively), despite the absence of the same behavior for ermC and tetM, respectively. Interestingly, the gene mecA was not correlated with resistance to methicillin or any other β-lactam. Correlation showed that slime-producing isolates had more resistance to antibiotics than those of nonslime producers. The multiple correlations between antibiotic resistance phenotypes and resistance genes indicate a complex nature of resistance in Staphylococcus species. The antimicrobial resistance could potentially spread to the community and thus, the resistance of Staphylococcus species to various antibiotics does not depend only on the use of a single antimicrobial, but also extends to other unrelated classes of antimicrobials.202031750778