Drug resistance of 100 clinical strains of Enterococcus spp

The aim of this study was to evaluate the drug susceptibility of 100 Enterococcus spp. strains isolated from patients hospitalized in State Clinical Hospital No 1 in Warsaw. All strains were identified (API 20 STREP) and their susceptibility to antibiotics was tested (ATB STREP) in automatic ATB system. Additionally, PYRase activity, beta-lactamase production (in nitrocefin test), MICs for vancomycin and teicoplanin (E test), HLAR--high level aminoglycoside resistance and susceptibility to vancomycin, teicoplanin, piperacillin and piperacillin/tazobactam (disc diffusion method) were determined. E. faecalis ATCC 29212 was used as the control strain. Fifty E. faecalis, 45 E. faecium, 2 E. casseliflavus, 2 E. durans and 1 E. avium strain were cultured. All strains were PYRase-positive and beta-lactamase-negative. Ten isolates demonstrated intermediate susceptibility to vancomycin (6--E. faecalis and 4--E. faecium). One E. faecalis strain was intermediately susceptible to both glycopeptides. One E. casseliflavus strain showed low-level resistance to vancomycin, but this strain was susceptible to teicoplanin--phenotype Van C. HLAR strains were found among 31 E. faecalis and 40 E. faecium strains. 48 E. faecalis strains were susceptible to piperacillin and 49 to piperacillin/tazobactam. Whereas, 41 E. faecium were resistant to both these drugs. Thirty six per cent of isolates were resistant to penicillin and ampicillin, 73% to erythromycin, 87% to tetracycline, 89% to lincomycin and 56% to nitrofurantoin. Some discrepancies were noticed between the results of different methods applied for susceptibility testing--ATB system, E test and disc diffusion. These discrepancies concerned HLAR detection and susceptibility to glycopeptides determination. The best methods were: disc-diffusion for HLAR detection and E test for determination of resistance to vancomycin and teicoplanin. Increasing resistance to antimicrobial agents is observed in clinical Enterococcus spp. isolates cultured in our laboratory, especially in E. faecium strains. It is necessary to control the dissemination of multiresistant Enterococcus spp. strains in hospital wards.     

Antimicrobial resistance of Enterococcus species isolated from produce

The purpose of this study was to characterize the antibiotic resistance profiles of Enterococcus species isolated from fresh produce harvested in the southwestern United States. Among the 185 Enterococcus isolates obtained, 97 (52%) were Enterococcus faecium, 38 (21%) were Enterococcus faecalis, and 50 (27%) were other Enterococcus species. Of human clinical importance, E. faecium strains had a much higher prevalence of resistance to ciprofloxacin, tetracycline, and nitrofurantoin than E. faecalis. E. faecalis strains had a low prevalence of resistance to antibiotics used to treat E. faecalis infections of both clinical and of agricultural relevance, excluding its intrinsic resistance patterns. Thirty-four percent of the isolates had multiple-drug-resistance patterns, excluding intrinsic resistance. Data on the prevalence and types of antibiotic resistance in Enterococcus species isolated from fresh produce may be used to describe baseline antibiotic susceptibility profiles associated with Enterococcus spp. isolated from the environment. The data collected may also help elucidate the role of foods in the transmission of antibiotic-resistant strains to human populations.     

Antibiotic resistance and virulence traits in clinical and environmental Enterococcus faecalis and Enterococcus faecium isolates

This study compared virulence and antibiotic resistance traits in clinical and environmental Enterococcus faecalis and Enterococcus faecium isolates. E. faecalis isolates harboured a broader spectrum of virulence determinants compared to E. faecium isolates. The virulence traits Cyl-A, Cyl-B, Cyl-M, gel-E, esp and acm were tested and environmental isolates predominantly harboured gel-E (80% of E. faecalis and 31.9% of E. faecium) whereas esp was more prevalent in clinical isolates (67.8% of E. faecalis and 70.4% of E. faecium). E. faecalis and E. faecium isolated from water had different antibiotic resistance patterns compared to those isolated from clinical samples. Linezolid resistance was not observed in any isolates tested and vancomycin resistance was observed only in clinical isolates. Resistance to other antibiotics (tetracycline, gentamicin, ciprofloxacin and ampicillin) was detected in both clinical and water isolates. Clinical isolates were more resistant to all the antibiotics tested compared to water isolates. Multi-drug resistance was more prevalent in clinical isolates (71.2% of E. faecalis and 70.3% of E. faecium) compared to water isolates (only 5.7% E. faecium). tet L and tet M genes were predominantly identified in tetracycline-resistant isolates. All water and clinical isolates resistant to ciprofloxacin and ampicillin contained mutations in the gyrA, parC and pbp5 genes. A significant correlation was found between the presence of virulence determinants and antibiotic resistance in all the isolates tested in this study (p<0.05). The presence of antibiotic resistant enterococci, together with associated virulence traits, in surface recreational water could be a public health risk.     

Highly conjugative pMG1-like plasmids carrying Tn1546-like transposons that encode vancomycin resistance in Enterococcus faecium

A total of 12 VanA-type vancomycin-resistant enterococci, consisting of 10 Enterococcus faecium isolates and two Enterococcus avium isolates, were examined in detail. The vancomycin resistance conjugative plasmids pHTalpha (65.9 kbp), pHTbeta (63.7 kbp), and pHTgamma (66.5 kbp) were isolated from each of three different E. faecium strains. The plasmids transferred highly efficiently between enterococcus strains during broth mating and were homologous with pMG1 (Gm(r); 65.1 kb).     

Prevalence and antimicrobial resistance of enterococcus species isolated from retail meats

From March 2001 to June 2002, a total of 981 samples of retail raw meats (chicken, turkey, pork, and beef) were randomly obtained from 263 grocery stores in Iowa and cultured for the presence of Enterococcus spp. A total of 1,357 enterococcal isolates were recovered from the samples, with contamination rates ranging from 97% of pork samples to 100% of ground beef samples. Enterococcus faecium was the predominant species recovered (61%), followed by E. faecalis (29%), and E. hirae (5.7%). E. faecium was the predominant species recovered from ground turkey (60%), ground beef (65%), and chicken breast (79%), while E. faecalis was the predominant species recovered from pork chops (54%). The incidence of resistance to many production and therapeutic antimicrobials differed among enterococci recovered from retail meat samples. Resistance to quinupristin-dalfopristin, a human analogue of the production drug virginiamycin, was observed in 54, 27, 9, and 18% of E. faecium isolates from turkey, chicken, pork, and beef samples, respectively. No resistance to linezolid or vancomycin was observed, but high-level gentamicin resistance was observed in 4% of enterococci, the majority of which were recovered from poultry retail meats. Results indicate that Enterococcus spp. commonly contaminate retail meats and that dissimilarities in antimicrobial resistance patterns among enterococci recovered from different meat types may reflect the use of approved antimicrobial agents in each food animal production class.     

Drug resistance of Enterococcus species isolated from the urogenital system

Despite low virulence of enterococci, they have become important nosocomial pathogens. This has been correlated with the increased use of broad-spectrum antibiotics, particularly cephalosporins. Many strains of enterococci exhibit multiple drug resistance; the most important being high-level resistance (HLR) to penicillin (MIC > 100 mg/l) and gentamicin (MIC > 500 mg/l and 2000 mg/l) and/or streptomycin (MIC > 2000 mg/l). The investigation was performed on 92 strains, isolated from genito-urinary tract and recognised as Enterococcus sp. All strains were obtained from several microbiological laboratories of Gdańsk, Gdynia and Tczew. On biochemical reaction profiles species of enterococci were identified as: E. faecalis (72.8%), E. faecalis varians (9.8%), E. durans (7.6%) and E. faecium (9.8%). The minimal inhibitory concentration (MICs) of penicillin, ampicillin, azlocillin, imipenem, gentamicin, amicacin, ciprofioxacin and vancomycin were determined by the agar dilution method. None of these 92 enterococcal strains was vancomycin resistant. 22.2% of E. faecium and 7.5% of E. faecalis showed high-level resistance to penicillin. None of these strains were produced beta-lactamase. High-level resistance to streptomycin and gentamicin was detected. Both--high-level resistance to streptomycin and gentamicin--were found in 6% E. faecalis; 11.1% E. faecalis varians and 22.2% E. faecium.     

Antibiotic resistance and genotypic characterization by PFGE of clinical and environmental isolates of enterococci

Fifty-four Enterococcus faecalis and 20 Enterococcus faecium isolates from clinical and non-human sources in Rome, Italy, were characterized by antibiotic resistance and pulsed field gel electrophoresis (PFGE). Resistance to vancomycin, teicoplanin, ampicillin, and ciprofloxacin was more frequent in E. faecium than in E. faecalis, whereas high-level resistance to aminoglycoside was found primarily in E. faecalis. Multi-resistance was found primarily among clinical isolates, but was also observed among environmental isolates. Common genotypes shared among clinical and environmental isolates were observed, however, the majority of isolates occurred as unique, source-specific clones. Several PFGE types were associated with shared features in their antibiotic resistance patterns; evidences of clonal spread between and within wards were also noted. This is the first report indicating clonal relatedness between human and environmental enterococci isolated in Italy.     

High level of aminoglycoside resistance among Enterococcus faecalis and Enterococcus faecium strains

Enterococcus sp. strains are believed as important reason of serious nosocomial infections currently. These infections are cured by using combination of beta-lactams and aminoglycosides for their treatment. Enterococcus sp. resistant to high-level doses of aminoglycosides, beta-lactams and vancomycin are responsible for therapeutic failure. The aim of our study was to evaluate the incidence of isolation and susceptibility to antibiotics of HLAR Enterococcus sp. strains isolated between 2007 and 2010 from the patients of University Hospital No. 1 of dr A. Jurasz Collegium Medicum of L. Rydygier in Bydgoszcz Nicolaus Copernicus University in Toruń. Amongst 6137 Enterococcus sp. strains 1124 (18,3%) presented HLAR phenotype; 53,1% of them was identified as E. faecalis and 46,9% as E. faecium. The highest percentage of all examined strains was isolated from the patients of different surgery clinics, Intensive Care Units, and Pediatrics, Hematology and Oncology Clinic. HLAR and HLSR phenotypes were noted in E. faecalis, for 45,7% and 27,5% strains, in E. faecium - 29,8% and 9,5%, respectively. HLGR phenotype was presented twice more often in E. faecium than E. faecalis. Highest percentages of E. faecium resistant to glycopeptides and rifampicin were observed when compared with E. faecalis. The highest percentages of strains intermediate, resistant to vancomycin and resistant to glycopeptides were noted for E. faecium strains with phenotypes HLAR, HLGR and HLSR.     

Characterization of glycopeptides, aminoglycosides and macrolide resistance among Enterococcus faecalis and Enterococcus faecium isolates from hospitals in Tehran

The prevalence of glycopeptides, aminoglycosides and erythromycin resistance among Enterococcus faecalis and Enterococcus faecium was investigated. The susceptibility of 326 enterococcal hospital isolates to amikacin, kanamycin, netilmicin and tobramycin were determined using disk diffusion method. The minimum inhibitory concentration (MIC) of vancomycin, teicoplanin, gentamicin, streptomycin, and erythromycin were determined by microbroth dilution method. The genes encoding aminoglycoside modifying enzymes described as AMEs genes, erythromycin-resistant methylase (erm) and vancomycin-resistant were targeted by multiplex-PCR reaction. High level resistance (HLR) to gentamicin and streptomycin among enterococci isolates were 52% and 72% respectively. The most prevalent of AMEs genes were aac (6')-Ie aph (2") (63%) followed by aph (3')-IIIa (37%). The erythromycin resistance was 45% and 41% of isolates were positive for ermB gene. The ermA gene was found in 5% of isolates whereas the ermC gene was not detected in any isolates. The prevalence of vancomycin resistant enterococci (VRE) was 12% consisting of E. faecalis (6%) and E. faecium (22%) and all of them were VanA Phenotype. The results demonstrated that AMEs, erm and van genes are common in enterococci isolated in Tehran. Furthermore our results show an increase in the rate of vancomycin resistance among enterococci isolates in Iran.     

Antibiotic resistance and virulence factors among clinical and food enterococci isolated in Slovakia

The resistance to antibiotics and the distribution of virulence factors in enterococci isolated from traditional Slovak sheep cheese bryndza was compared with strains from human infections. The occurrence of 4 enterococcal species was observed in 117 bryndza-cheese isolates. The majority of strains were identified as E. faecium (76 %) and E. faecalis (23 %). Several strains of E. durans and 1 strain of E. hirae were also present. More than 90 % of strains isolated from 109 clinical enterococci were E. faecalis, the rest belonged to E. faecium. The resistance to 6 antimicrobial substances (ampicillin, ciprofloxacin, higher concentration of gentamicin, nitrofurantoin, tetracycline and vancomycin) was tested in clinical and food enterococci. A higher level of resistance was found in clinical than in food strains and E. faecium had a higher resistance than E. faecalis; no resistance to vancomycin was detected. The occurrence of 3 virulence-associated genes, cylA (coding for hemolysin), gelE (coding for gelatinase) and esp (coding for surface protein) was monitored. Differences were found in the distribution of cylA gene between clinical and bryndza-cheese E. faecalis strains; in contrast to clinical strains (45 %), cylA gene was detected in 22 % of food isolates. The distribution of 2 other virulence factors, gelE and esp, was not significantly different in the two groups of E. faecalis strains. cylA and gelE genes were not detected in E. faecium but more than 70 % of clinical E. faecium were positive for esp, even thought none of the 79 E. faecium cheese isolates contained this gene.     

肠球菌的临床感染与耐药性分析

目的了解温州医学院附属第一医院临床分离主要肠球菌的分布及其对常用抗菌药物的耐药现状,以指导临床合理用药。方法对2008年至2011年临床分离的635株粪肠球菌和屎肠球菌的标本来源和药敏结果进行回顾性分析。结果各种临床标本中两种肠球菌的分布比例存在差异,总体以尿液标本所占比例最多,且屎肠球菌的总体分离率高于粪肠球菌。粪肠球菌对利奈唑胺、氨苄西林、万古霉素、呋喃妥因和替考拉宁的耐药率都在5．0％以下,对莫西沙星和青霉素G的耐药率也仅为7．0％和6．7％;屎肠球菌对莫西沙星、左旋氧氟沙星、环丙沙星、氨苄西林、青霉素G和红霉素的耐药率都在90．0％以上,对利奈唑胺、万古霉素、替考拉宁和奎奴敏感。粪肠球菌的多重耐药株占总数的26．4％,屎肠球菌的多重耐药株占总数的78．2％。结论粪肠球菌和屎肠球菌对15种抗菌药物的耐药情况不同,屎肠球菌具有更高的耐药率和更广的耐药谱。临床应根据药敏试验的结果合理选择抗菌药物,以防止耐药菌株的产生和播散。     

血流感染粪肠球菌和屎肠球菌的临床分布及耐药研究

回顾性分析上海市某三甲医院血培养阳性标本中粪肠球菌和屎肠球菌的临床分布及对抗菌药物的耐药特征,为临床治疗其所致感染奠定基础。收集上海市某三甲医院2012年2月—2016年9月血流感染患者血液标本中的粪肠球菌和屎肠球菌,采用法国生物梅里埃公司的VITEK 2Compact全自动细菌鉴定和药敏分析系统进行细菌鉴定及药敏测定,研究细菌临床分布特点及对常用抗菌药物的耐药特征。共分离获得30株粪肠球菌和17株屎肠球菌。粪肠球菌样本主要来自泌尿科、消化科和血液科,所占比例分别为13.33%、16.67%和10.00%。粪肠球菌对青霉素、氨苄西林、环丙沙星、左氧氟沙星、四环素和红霉素的耐药率分别为13.33%、10.00%、36.67%、33.33%、66.67%和60.00%。屎肠球菌样本主要来自消化科(29.41%),其对以上抗菌药物的耐药率分别为88.24%、82.35%、88.24%、76.47%、23.53%和70.59%。屎肠球菌对青霉素、氨苄西林、环丙沙星和左氧氟沙星的耐药率显著高于粪肠球菌,而对四环素的耐药率显著低于粪肠球菌。两者均对替加环素、利奈唑胺和万古霉素敏感,但万古霉素对屎肠球菌的最低抑菌浓度显著低于粪肠球菌。结果提示,屎肠球菌对青霉素、氨苄西林、环丙沙星、左氧氟沙星的耐药率高于屎肠球菌,对万古霉素敏感,且其万古霉素最低抑菌浓度低于粪肠球菌。本研究为治疗这两种细菌所致感染的经验性用药提供了数据支持。     

Occurrence of high-level aminoglycoside resistance in environmental isolates of enterococci.

High-level resistance to aminoglycosides was observed in environmental isolates of enterococci. Various aquatic habitats, including agricultural runoff, creeks, rivers, wastewater, and wells, were analyzed. Strains of Enterococcus faecalis, E. faecium, E. gallinarum, and other Enterococcus spp. demonstrated multiple antibiotic resistance patterns to aminoglycosides.     

Antimicrobial resistance of Enterococcus sp. isolated from the intestinal tract of patients from a university hospital in Brazil

This study reports the results about antimicrobial resistance of Enterococcus spp. isolated from intestinal tract of patients from a university hospital in Brazil. The identification of strains at species level was performed by conventional biochemical tests, API 20 Strep (bioMérieux), and polymerase chain reaction assay. The species distribution was E. faecium (34%), followed by E. faecalis (33%), E. gallinarum (23.7%), E. casseliflavus (5.2%), E. avium (1%), and E. hirae (1%). Intrinsic resistance to vancomycin characterized by presence of vanC genes was found in E. gallinarum and E. casseliflavus. The high prevalence of VanC phenotype enterococci is very important because these species have been reported as causing a wide variety of infections. Vancomycin-resistant E. faecium or E. faecalis were not found and no one isolate of these species was a beta-lactamase producer. Thirteen clinical isolates of enterococci (13.4%) showed multiresistance patterns, which were defined by resistance to three classes of antibiotics plus resistance to at least one aminoglycoside (gentamicin and/or streptomycin). The resistance to several antimicrobials shown by enterococcal strains obtained in this study is of concern because of the decrease in the therapeutic options for treatment of infections caused by enterococci.     

Antimicrobial susceptibility of<Emphasis Type="Italic">Enterococcus</Emphasis> species isolated from slovak bryndza cheese

Three hundred and ten enterococcal isolates (178 Enterococcus faecium, 68 E. durans, 49 E. faecalis, 8 E. italicus, 3 E. gallinarum, 3 E. casseliflavus, and 1 E. hirae) from Slovak Bryndza cheese were evaluated for susceptibility to nine antimicrobial agents (vancomycin, teicoplanin, ampicillin, streptomycin, gentamicin, erythromycin, rifampicin, nitrofurantoin, and ciprofloxacin). All enterococcal isolates from Bryndza cheese were susceptible to ampicillin, streptomycin, gentamicin, vancomycin, and teicoplanin as determined by the disk diffusion method. Vancomycin resistance genes vanA and vanB were not detected. Resistance rates of enterococcal isolates to rifampicin, erythromycin, ciprofloxacin, and nitrofurantoin were 24, 26, 2, and 1 %, respectively. Thirty-six % of E. faecium isolates and 22 % of the E. faecalis isolates were resistant to erythromycin. Resistance to rifampicin was similar in E. faecium (31 %) and E. faecalis (29 %). Both E. faecium and E. faecalis strains showed the same resistance to ciprofloxacin (2 %). E. durans isolates showed low levels of resistance to rifampicin, erythromycin, ciprofloxacin, and nitrofurantoin (1-4 %). Forty-eight (30 %) of the E. faecium isolates, two (3 %) of the E. durans isolates, and six (12 %) of the E. faecalis isolates exhibited multidrug resistance. The highest frequency of resistant enterococci was observed in Bryndza produced in winter season.     

Persistence of vancomycin-resistant enterococci in New Zealand broilers after discontinuation of avoparcin use

Large amounts of tylosin, zinc-bacitracin, and avilamycin are currently used as prophylactics in New Zealand broiler production. Avoparcin was also used from 1977 to 2000. A total of 382 enterococci were isolated from 213 fecal samples (147 individual poultry farms) using enrichment broths plated on m-Enterococcus agar lacking antimicrobials. These isolates were then examined to determine the prevalence of antimicrobial resistance. Of the 382 isolates, 5.8% (22 isolates) were resistant to vancomycin, and 64.7% were resistant to erythromycin. The bacitracin MIC was > or =256 microg/ml for 98.7% of isolates, and the avilamycin MIC was > or =8 microg/ml for 14.9% of isolates. No resistance to ampicillin or gentamicin was detected. Of the 22 vancomycin-resistant enterococci (VRE) isolates, 18 (81.8%) were Enterococcus faecalis, 3 were Enterococcus faecium, and 1 was Enterococcus durans. However, when the 213 fecal enrichment broths were plated on m-Enterococcus agar containing vancomycin, 86 VRE were recovered; 66% of these isolates were E. faecium and the remainder were E. faecalis. Vancomycin-resistant E. faecium isolates were found to have heterogenous pulsed-field gel electrophoresis (PFGE) patterns of SmaI-digested DNA, whereas the PFGE patterns of vancomycin-resistant E. faecalis isolates were identical or closely related, suggesting that this VRE clone is widespread throughout New Zealand. These data demonstrate that vancomycin-resistant E. faecalis persists in the absence and presence of vancomycin-selective pressure, thus explaining the dominance of this VRE clone even in the absence of avoparcin.     

Species distribution and antimicrobial resistance of enterococci isolated from surface and ocean water

Aims: The species identification and antimicrobial resistance profiles were determined for enterococci isolated from Southern California surface and ocean waters. Methods and Results: Species identification was determined for 1413 presumptive Enterococcus isolates from urban runoff, bay, ocean and sewage water samples. The most frequently isolated species were Enterococcus faecalis, Enterococcus faecium, Enterococcus hirae, Enterococcus casseliflavus and Enterococcus mundtii. All five of these species were isolated from ocean and bay water with a frequency ranging from 7% to 36%. Enterococcus casseliflavus was the most frequently isolated species in urban runoff making up 36–65% of isolates while E. faecium was the most frequently isolated species in sewage making up 53–78% of isolates. The similar distribution of species in urban runoff and receiving water suggests that urban runoff may be the source of Enterococcus. No vancomycin or high level gentamycin resistance was detected in E. faecalis and E. faecium isolates. Conclusions: Enterococcus faecalis, E. faecium, E. casseliflavus and E. mundtii are the most commonly isolated Enterococcus species from urban runoff and receiving waters in Southern California. Significance and Impact of the Study: Determination of the Enterococcus species isolated from receiving waters and potential pollution sources may assist in determining the sources of pollution.     

Susceptibility to vancomycin of enterococci isolated from dairy products

The antibiotic vancomycin is often used in clinical therapy against multiple antibiotic-resistant bacteria. Twenty strains of enterococci, either Enterococcus faecium or Ent. faecalis , isolated from different cheeses were tested for resistance to vancomycin in liquid medium. Minimum inhibitory concentration (MIC) values ranged from less than 1 to 4 μg ml⁻¹. A 399 bp intragenic fragment of the van A gene was not observed after amplification of total DNA of the strains. It seems, therefore, that resistance to vancomycin, which is a common trait for enterococci of nosocomial origin, is not widespread among dairy isolates.     

Identification and characterization of enterococci from bryndza cheese

AIMS: To identify enterococci isolated from sheep milk cheese--bryndza, and to compare differences in the composition of enterococcal microflora affected by the season, and to evaluate the potential presence of vancomycin resistance and virulence determinants. METHODS AND RESULTS: Bacterial strains were isolated during analysis of bryndza cheese and identified on the genus and species level by phenotypic methods and with commercial biochemical sets. The identification of the species, Enterococcus faecium, Ent. durans and Ent. faecalis, was confirmed by PCR using species-specific primers for ddl genes. PCR was also used for assessment of presence of vanA and vanB genes and virulence determinants gelE, agg and cytolysin genes namely: cylL(L), cylL(S), cylM, cylB and cylA. Among 308 Enterococcus sp. strains, 177 isolates were proved to be Ent. faecium, 59 to be Ent. durans and 41 to be Ent. faecalis. Vancomycin resistance genes vanA and vanB were not detected. Agar plate testing confirmed their absence. Gene gelE, however, was found in 20 Ent. faecalis isolates, but only 13 of them showed gelatinase-positive phenotype. Seven isolates had five cytolysin genes, but none of the isolates exhibited a positive haemolytic phenotype. Four isolates possessed the agg gene. The prevalence of Ent. faecium species was highest in samples from the winter season harvest. CONCLUSIONS: Ent. faecium is the dominant enterococcal species in bryndza cheese and the most prevalent in the winter season product. None of the Enterococcus sp. strains was proved to have vanA or vanB genes and the vancomycin resistance. SIGNIFICANCE AND IMPACT OF THE STUDY: To our knowledge, this is the first report of enterococcal microflora in bryndza cheese and its evaluation for the presence of vanA and vanB genes as well as virulence determinants.     

Distribution of antimicrobial resistance and virulence genes in Enterococcus spp. and characterization of isolates from broiler chickens

Enterococci are now frequent causative agents of nosocomial infections. In this study, we analyzed the frequency and distribution of antibiotic resistance and virulence genotypes of Enterococcus isolates from broiler chickens. Fecal and cecal samples from nine commercial poultry farms were collected to quantify total enterococci. Sixty-nine presumptive enterococci were isolated and identified by API 20 Strep, and their susceptibilities to antibiotics were determined. Genotypes were assessed through the use of a novel DNA microarray carrying 70 taxonomic, 17 virulence, and 174 antibiotic resistance gene probes. Total enterococcal counts were different from farm to farm and between sample sources (P < 0.01). Fifty-one (74%) of the isolates were identified as E. faecium, whereas nine (13%), seven (10%), and two (3%) isolates were identified as E. hirae, E. faecalis, and E. gallinarum, respectively. Multiple-antibiotic resistance was evident in E. faecium and E. faecalis isolates. The most common multiple-antibiotic resistance phenotype was Bac Ery Tyl Lin Str Gen Tet Cip. Genes conferring resistance to aminoglycoside (aac, aacA-aphD, aadB, aphA, sat4), macrolide (ermA, ermB, ermAM, msrC), tetracycline (tetL, tetM, tetO), streptogramin (satG_vatE8), bacitracin (bcrR), and lincosamide (linB) antibiotics were detected in corresponding phenotypes. A range of 9 to 12 different virulence genes was found in E. faecalis, including ace, agg, agrB(Efs) (agrB gene of E. faecalis), cad1, the cAM373 and cCF10 genes, cob, cpd1, cylAB, efaA(Efs), and gelE. All seven E. faecalis isolates were found to carry the gelE gene and to hydrolize gelatin and bile salts. Results from this study showed the presence of enterococci of public and environmental health concerns in broiler chicken farms and demonstrated the utility of a microarray to quickly and reliably analyze resistance and virulence genotypes of Enterococcus spp.