Molecular basis of resistance to macrolides, lincosamides and streptogramins in Staphylococcus hominis strains isolated from clinical specimens. - Related Documents




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244001.0000Molecular basis of resistance to macrolides, lincosamides and streptogramins in Staphylococcus hominis strains isolated from clinical specimens. Coagulase-negative staphylococci (CoNS) are the most frequently isolated bacteria from the blood and the predominant cause of nosocomial infections. Macrolides, lincosamides and streptogramin B (MLSB) antibiotics, especially erythromycin and clindamycin, are important therapeutic agents in the treatment of methicillin-resistant staphylococci infections. Among CoNS, Staphylococcus hominis represents the third most common organism. In spite of its clinical significance, very little is known about its mechanisms of resistance to antibiotics, especially MLSB. Fifty-five S. hominis isolates from the blood and the surgical wounds of hospitalized patients were studied. The erm(C) gene was predominant in erythromycin-resistant S. hominis isolates. The methylase genes, erm(A) and erm(B), were present in 15 and 25% of clinical isolates, respectively. A combination of various erythromycin resistance methylase (erm) genes was detected in 15% S. hominis isolates. The efflux gene msr(A) was detected in 18% of isolates, alone in four isolates, and in different combinations in a further six. The lnu(A) gene, responsible for enzymatic inactivation of lincosamides was carried by 31% of the isolates. No erythromycin resistance that could not be attributed to the genes erm(A), erm(B), erm(C) and msr(A) was detected. In S. hominis, 75 and 84%, respectively, were erythromycin resistant and clindamycin susceptible. Among erythromycin-resistant S. hominis isolates, 68% of these strains showed the inducible MLSB phenotype. Four isolates harbouring the msr(A) genes alone displayed the MSB phenotype. These studies indicated that resistance to MLSB in S. hominis is mostly based on the ribosomal target modification mechanism mediated by erm genes, mainly the erm(C), and enzymatic drug inactivation mediated by lnu(A).201626253583
243910.9999Differences in distribution of MLS antibiotics resistance genes in clinical isolates of staphylococci belonging to species: S. epidermidis, S. hominis, S. haemolyticus, S. simulans and S. warneri. BACKGROUND: Macrolides and lincosamides are two leading types of antibiotics commonly used in therapies. The study examines the differences in resistance to these antibiotics and their molecular bases in S. epidermidis as well as in rarely isolated species of coagulase-negative staphylococci such as S. hominis, S. haemolyticus, S. warneri and S. simulans. The isolates were tested for the presence of the erm(A), erm(B), erm(C), lnu(A), msr(A), msr(B), mph(C), ere(A) and ere(B) genes. Phenotypic resistance to methicillin and mecA presence were also determined. RESULTS: The MLS(B) resistance mechanism was phenotypically found in isolates of species included in the study. The most prevalent MLS(B) resistance mechanism was observed in S. hominis, S. haemolyticus and S. epidermidis isolates mainly of the MLS(B) resistance constitutive type. Macrolide, lincosamide and streptogramin B resistance genes were rarely detected in isolates individually. The erm(B), ere(A) and ere(B) genes were not found in any of the strains. The erm(A) gene was determined only in four strains of S. epidermidis and S. hominis while lnu(A) was seen in eight strains (mainly in S. hominis). The erm(C) gene was present in most of S. epidermidis strains and predominant in S. hominis and S. simulans isolates. The examined species clearly differed between one another in the repertoire of accumulated genes. CONCLUSIONS: The presence of genes encoding the MLS(B) resistance among CoNS strains demonstrates these genes' widespread prevalence and accumulation in opportunistic pathogens that might become gene reservoir for bacteria with superior pathogenic potential.201931182020
240620.9998Prevalence 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
239230.9998Characterization of the resistome and predominant genetic lineages of Gram-positive bacteria causing keratitis. Bacterial keratitis is a vision-threatening infection mainly caused by Gram-positive bacteria (GPB). Antimicrobial therapy is commonly empirical using broad-spectrum agents with efficacy increasingly compromised by the emergence of antimicrobial resistance. We used a combination of phenotypic tests and genome sequencing to identify the predominant lineages of GPB causing keratitis and to characterize their antimicrobial resistance patterns. A total of 161 isolates, including Staphylococcus aureus (n = 86), coagulase-negative staphylococci (CoNS; n = 34), Streptococcus spp. (n = 34), and Enterococcus faecalis (n = 7), were included. The population of S. aureus isolates consisted mainly of clonal complex 5 (CC5) (30.2%). Similarly, the population of Staphylococcus epidermidis was homogenous with most of them belonging to CC2 (78.3%). Conversely, the genetic population of Streptococcus pneumoniae was highly diverse. Resistance to first-line antibiotics was common among staphylococci, especially among CC5 S. aureus. Methicillin-resistant S. aureus was commonly resistant to fluoroquinolones and azithromycin (78.6%) and tobramycin (57%). One-third of the CoNS were resistant to fluoroquinolones and 53% to azithromycin. Macrolide resistance was commonly caused by erm genes in S. aureus, mphC and msrA in CoNS, and mefA and msr(D) in streptococci. Aminoglycoside resistance in staphylococci was mainly associated with genes commonly found in mobile genetic elements and that encode for nucleotidyltransferases like ant(4')-Ib and ant(9)-Ia. Fluroquinolone-resistant staphylococci carried from 1 to 4 quinolone resistance-determining region mutations, mainly in the gyrA and parC genes. We found that GPB causing keratitis are associated with strains commonly resistant to first-line topical therapies, especially staphylococcal isolates that are frequently multidrug-resistant and associated with major hospital-adapted epidemic lineages.202438289077
238940.9998Antibiotic 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
594150.9998Characterization of macrolide resistance genes in Haemophilus influenzae isolated from children with cystic fibrosis. OBJECTIVES: to determine the mechanism(s) of macrolide resistance in Haemophilus influenzae isolated from cystic fibrosis (CF) patients participating in a randomized placebo-controlled trial of azithromycin. METHODS: macrolide susceptibility, mutations and carriage of the macrolide resistance genes erm(A), erm(B), erm(C), erm(F) and mef(A) were determined using PCR assays and sequencing or hybridization of the PCR products. H. influenzae isolates were used as donors in conjugation studies with H. influenzae and Enterococcus faecalis recipients. Transconjugant susceptibility and the macrolide resistance genes carried were determined. RESULTS: of the 106 H. influenzae isolates, 27 were resistant and 78 intermediate resistant to azithromycin and/or erythromycin. All isolates carried one or more macrolide resistance gene(s), with the mef(A), erm(B) and erm(F) genes found in 74%, 31% and 29% of the isolates, respectively. None of the selected isolates had L4 or L22 mutations. Twenty-five donors, with various macrolide MICs, transferred macrolide resistance genes to H. influenzae Rd (3.5 × 10(-7)-1 × 10(-10)) and/or E. faecalis (1 × 10(-7)-1 × 10(-8)) recipients. The H. influenzae transconjugants were phenotypically resistant or intermediate to both macrolides while E. faecalis transconjugants were erythromycin resistant. CONCLUSIONS: this is the first identification of erm(A), erm(C) and erm(F) genes in H. influenzae or bacteria from CF patients and the first characterization of macrolide gene transfer from H. influenzae donors. The high level of H. influenzae macrolide gene carriage suggests that the use of azithromycin in the CF population may ultimately reduce the effectiveness of continued or repeated macrolide therapy.201121081549
240760.9998Antibiotic resistance genes and identification of staphylococci collected from the production chain of swine meat commodities. Staphylococci harbouring antibiotic resistance (AR) genes may represent a hazard for human health and, as other resistant food-related bacteria, they contribute to the spread of AR. In this study, we isolated resistant staphylococci from an entire swine production chain and investigated the occurrence of 11 genes [aac(6')Ie-aph(2'')Ia, blaZ, mecA, vanA, vanB, ermA, ermB, ermC, tet(M), tet(O) and tet(K)] encoding resistance to some antibiotics largely used in clinical practice. The 66 resistant staphylococcal isolates were identified as Staphylococcus epidermidis (27 isolates), Staphylococcus aureus (12), Staphylococcus xylosus (12), Staphylococcus simulans (5), Staphylococcus pasteuri (4), Staphylococcus carnosus (3), Staphylococcus lentus (2) and Staphylococcus sciuri (1). Specific-PCR detection of AR genes showed the prevalence of the tet(K) gene in most of the isolates (89.4%), followed by tet(M) and ermC (about 75%); mecA was detected in more than half of S. aureus and S. epidermidis isolates. The genes vanA and vanB were not retrieved. It was found that a high proportion of coagulase-positive and -negative isolates are multidrug-resistant and some of them carry up to six AR genes. Our findings show that the swine production chain is a source of antibiotic-resistant staphylococci suggesting the importance of resistance surveillance in the food production environment.200817993395
553870.9998Phenotypic and genotypic antimicrobial susceptibility pattern of Streptococcus spp. isolated from cases of clinical mastitis in dairy cattle in Poland. Mastitis of dairy cattle is one of the most frequently diagnosed diseases worldwide. The main etiological agents of mastitis are bacteria of the genus Streptococcus spp., in which several antibiotic resistance mechanisms have been identified. However, detailed studies addressing this problem have not been conducted in northeastern Poland. Therefore, the aim of our study was to analyze, on phenotypic and genotypic levels, the antibiotic resistance pattern of Streptococcus spp. isolated from clinical cases of mastitis from dairy cattle in this region of Poland. The research was conducted using 135 strains of Streptococcus (Streptococcus uberis, n = 53; Streptococcus dysgalactiae, n = 41; Streptococcus agalactiae, n = 27; other streptococci, n = 14). The investigation of the antimicrobial susceptibility to 8 active substances applied in therapy in the analyzed region, as well as a selected bacteriocin (nisin), was performed using the minimum inhibitory concentration method. The presence of selected resistance genes (n = 14) was determined via PCR. We also investigated the correlation between the presence of resistance genes and the antimicrobial susceptibility of the examined strains in vitro. The highest observed resistance of Streptococcus spp. was toward gentamicin, kanamycin, and tetracycline, whereas the highest susceptibility occurred toward penicillin, enrofloxacin, and marbofloxacin. Additionally, the tested bacteriocin showed high efficacy. The presence of 13 analyzed resistance genes was observed in the examined strains [gene mef(A) was not detected]. In most strains, at least one resistance gene, mainly responsible for resistance to tetracyclines [tet(M), tet(K), tet(L)], was observed. However, a relationship between the presence of a given resistance gene and antimicrobial susceptibility on the phenotypic level was not always observed.201728601447
240080.9998Antimicrobial susceptibility and distribution of antimicrobial-resistance genes among Enterococcus and coagulase-negative Staphylococcus isolates recovered from poultry litter. Data on the prevalence of antimicrobial resistant enterococci and staphylococci from the poultry production environment are sparse in the United States. This information is needed for science-based risk assessments of antimicrobial use in animal husbandry and potential public-health consequences. In this study, we assessed the susceptibility of staphylococci and enterococci isolated from poultry litter, recovered from 24 farms across Georgia, to several antimicrobials of veterinary and human health importance. Among the 90 Enterococcus isolates recovered, E. hirae (46%) was the most frequently encountered species, followed by E. faecium (27%), E. gallinarum (12%), and E. faecalis (10%). Antimicrobial resistance was most often observed to tetracycline (96%), followed by clindamycin (90%), quinupristin-dalfopristin (62%), penicillin (53%), erythromycin (50%), nitrofurantoin (49%), and clarithromycin (48%). Among the 110 staphylococci isolates recovered, only coagulase-negative staphylococci (CNS) were identified with the predominant Staphylococcus species being S. sciuri (38%), S. lentus (21%), S. xylosus (14%) and S. simulans (12%). Resistance was less-frequently observed among the Staphylococcus isolates for the majority of antimicrobials tested, as compared with Enterococcus isolates, and was primarily limited to clarithromycin (71%), erythromycin (71%), clindamycin (48%), and tetracycline (38%). Multidrug resistance (MDR) phenotypes were prevalent in both Enterococcus and Staphylococcus; however, Enterococcus exhibited a statistically significant difference in the median number of antimicrobials to which resistance was observed (median = 5.0) compared with Staphylococcus species (median = 3.0). Because resistance to several of these antimicrobials in gram-positive bacteria may be attributed to the shuttling of common drug-resistance genes, we also determined which common antimicrobial-resistance genes were present in both enterococci and staphylococci. The antimicrobial resistance genes vat(D) and erm(B) were present in enterococci, vgaB in staphylococci, and mobile genetic elements Tn916 and pheromone-inducible plasmids were only identified in enterococci. These data suggest that the disparity in antimicrobial-resistance phenotypes and genotypes between enterococci and staphylococci isolated from the same environment is, in part, because of barriers preventing exchange of mobile DNA elements.200718251398
244190.9998Phenotypic 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
5534100.9998Antibiotic 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
5498110.9998The 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.202539747570
5902120.9998Antimicrobial Resistance Profiles of Listeria monocytogenes and Listeria innocua Isolated from Ready-to-Eat Products of Animal Origin in Spain. The objective of this work was to investigate the antimicrobial resistance in Listeria spp. isolated from food of animal origin. A total of 50 Listeria strains isolated from meat and dairy products, consisting of 7 Listeria monocytogenes and 43 Listeria innocua strains, were characterized for antimicrobial susceptibility against nine antimicrobials. The strains were screened by real-time PCR for the presence of antimicrobial resistance genes: tet M, tet L, mef A, msr A, erm A, erm B, lnu A, and lnu B. Multidrug resistance was identified in 27 Listeria strains, 4 belonging to L. monocytogenes. Resistance to clindamycin was the most common resistance phenotype and was identified in 45 Listeria strains; the mechanisms of resistance are still unknown. A medium prevalence of resistance to tetracycline (15 and 9 resistant and intermediate strains) and ciprofloxacin (13 resistant strains) was also found. Tet M was detected in Listeria strains with reduced susceptibility to tetracycline, providing evidence that both L. innocua and L. monocytogenes displayed acquired resistance. The presence of antimicrobial resistance genes in L. innocua and L. monocytogenes indicates that these genes may be transferred to commensal and pathogenic bacteria via the food chain; besides this, antibiotic resistance in L. monocytogenes could compromise the effective treatment of listeriosis in humans.201728355096
2390130.9998Identification, antimicrobial susceptibility, and virulence factors of Enterococcus spp. strains isolated from Camels in Canary Islands, Spain. This study investigated the presence of Enterococcus spp. strains in camel faeces, their virulence factors, and resistance to the antibiotics commonly used as therapy of enterococcal infections. One hundred and seventy three Enterococcus strains were isolated and identified to species level using polymerase chain reaction (PCR). Susceptibility to 11 antimicrobials was determined by disk diffusion method. Minimal Inhibitory Concentrations (MIC) of penicillin, ampicillin, vancomycin, teicoplanin, gentamicin, and streptomycin were all determined. Genes encoding resistance to vancomycin, tetracycline, and erythromycin as well as genes encoding some virulence factors were identified by PCR. Enterococcus hirae (54.3%) and Enterococcus faecium (25.4%) were the species most frequently isolated. None of the strains were resistant to vancomycin, teicoplanin, ampicillin or showed high level aminoglycoside resistance (HLAR). Strains resistant to rifampicin (42.42%) were those most commonly found followed those resistant to trimethoprim - sulfamethoxazole (33.33%). The genes tetM, tetL, vanC1, and vanC2-C3 were detected in some strains. Virulence genes were not detected. Monitoring the presence of resistant strains of faecal enterococci in animal used with recreational purposes is important to prevent transmission of those strains to humans and to detect resistance or virulence genes that could be transferred to other clinically important bacteria.201526455369
2909140.9997Determination 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
2393150.9997Detection of a mecC-positive Staphylococcus saprophyticus from bovine mastitis in Argentina. INTRODUCTION: Bovine mastitis causes important economic losses in the dairy industry. Coagulase-negative staphylococci (CNS) are a group of bacteria commonly isolated from bovine mastitis and can display resistance to a wide range of antimicrobial agents. OBJECTIVES: The objective of this study was to determine staphylococcal resistance towards β-lactam, macrolide and lincosamide antimicrobials in quarters previously treated with third-generation cephalosporin and after lincosamide intramammary therapy. METHODS: Sick quarters of eighteen cows from Villaguay, Entre Ríos (Argentina) with clinical mastitis were studied. All staphylococcal isolates were tested by disk diffusion for their antimicrobial susceptibilities. Cefoxitin resistance was investigated by PCR and sequencing for both the mecA and mecC genes. RESULTS: Resistances to penicillin, oxacillin and cefoxitin were observed, whereas no resistance to macrolide and lincosamide was detected. A cefoxitin-resistant Staphylococcus saprophyticus was found to be mecA-negative but mecC-positive. CONCLUSIONS: This study reports for the first time the mecC gene from a CNS in bovine mastitis in South America. Because CNS may act as reservoirs of antimicrobial resistance genes, they can be seen as a potential public health threat with respect to antimicrobial resistance and the development of multiple resistance. Also, the emergence of methicillin-resistant phenotypes will limit therapeutic options.201728732791
2399160.9997Ready-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
2388170.9997Antibiotic 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
2442180.9997Macrolide, lincosamide, and streptogramin B resistance in lipophilic Corynebacteria inhabiting healthy human skin. Corynebacteria exist as part of human skin microbiota. However, under some circumstances, they can cause opportunistic infections. The subject of the study was to examine the macrolide-lincosamide-streptogramin B (MLSB) antibiotic resistance in 99 lipophilic strains of Corynebacterium genus isolated from the skin of healthy men. Over 70% of the tested strains were resistant to erythromycin and clindamycin. All of which demonstrated a constitutive type of MLSB resistance mechanism. In all strains, there were being investigated the erm(A), erm(B), erm(C), erm(X), lin(A), msr(A), and mph(C) genes that could be responsible for the different types of resistance to marcolides, lincosamides, and streptogramin B. In all strains with the MLSB resistance phenotype, the erm(X) gene was detected. None of the other tested genes were discovered. Strains harboring the erm(X) gene were identified using a phenotypic method based on numerous biological and biochemical tests. Identification of the chosen strains was compared with the results of API Coryne, MALDI-TOF MS, and 16S rDNA sequencing methods. Only 7 out of the 23 investigated resistant strains provided successful results in all the used methods, showing that identification of this group of bacteria is still a great challenge. The MLSB resistance mechanism was common in most frequently isolated from healthy human skin Corynebacterium tuberculostearicum and Corynebacterium jeikeium strains. This represents a threat as these species are also commonly described as etiological factors of opportunistic infections.201424735183
5428190.9997Antimicrobial resistance and prevalence of resistance genes of obligate anaerobes isolated from periodontal abscesses. BACKGROUND: This study attempts to determine the antimicrobial resistance profiles of obligate anaerobic bacteria that were isolated from a periodontal abscess and to evaluate the prevalence of resistance genes in these bacteria. METHODS: Forty-one periodontal abscess samples were cultivated on selective and non-selective culture media to isolate the oral anaerobes. Their antibiotic susceptibilities to clindamycin, doxycycline, amoxicillin, imipenem, cefradine, cefixime, roxithromycin, and metronidazole were determined using the agar dilution method, and polymerase chain reaction assays were performed to detect the presence of the ermF, tetQ, nim, and cfxA drug resistance genes. RESULTS: A total of 60 different bacterial colonies was isolated and identified. All of the isolates were sensitive to imipenem. Of the strains, 6.7%, 13.3%, 16.7%, and 25% were resistant to doxycycline, metronidazole, cefixime, and amoxicillin, respectively. The resistance rate for both clindamycin and roxithromycin was 31.7%. Approximately 60.7% of the strains had the ermF gene, and 53.3% of the amoxicillin-resistant strains were found to have the cfxA gene. Two nim genes that were found in eight metronidazole-resistant strains were identified as nimB. CONCLUSIONS: In the present study, the Prevotella species are the most frequently isolated obligate anaerobes from periodontal abscesses. The current results show their alarmingly high resistance rate against clindamycin and roxithromycin; thus, the use of these antibiotics is unacceptable for the empirical therapy of periodontal abscesses. A brief prevalence of four resistance genes in the anaerobic bacteria that were isolated was also demonstrated.201423659425