Population structure and safety aspects of Enterococcus strains isolated from artisanal dry fermented sausages produced in Argentina

Enterococci population from Argentinean artisanal dry fermented sausage was identified and their safety aspects were evaluated. Species-specific PCR was used to distinguish between Enterococcus faecium (56%) and Enterococcus faecalis (17%). Other isolates (27%) were identified as Enterococcus durans , Enterococcus casseliflavus and Enterococcus mundtii by using 16S RNA gene sequence. RAPD analyses showed different biotypes for Ent. faecium and Ent. faecalis species. Low incidence of antibiotic resistance and high virulence traits in Ent. casseliflavus and Ent. faecalis were found; the majority of the Ent. faecium strains were shown to be free of virulence factors. The absence of virulence/resistance traits and the anti-Listeria activity of Ent. faecium isolates may be exploited to enhance natural preservation thereby guaranteeing organoleptic/safety characteristics of artisanal fermented sausages.     

Incidence of Virulence Factors and Antibiotic Resistance among Enterococci Isolated from Food

The incidence of virulence factors among 48 Enterococcus faecium and 47 Enterococcus faecalis strains from foods and their antibiotic susceptibility were investigated. No strain was resistant to all antibiotics, and for some strains, multiple resistances were observed. Of E. faecium strains, 10.4% were positive for one or more virulence determinants, compared to 78.7% of E. faecalis strains. Strains exhibiting virulence traits were not necessarily positive for all traits; thus, the incidence of virulence factors may be considered to be strain specific.     

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.     

Molecular screening of Enterococcus virulence determinants and potential for genetic exchange between food and medical isolates

Enterococci are used as starter and probiotic cultures in foods, and they occur as natural food contaminants. The genus Enterococcus is of increased significance as a cause of nosocomial infections, and this trend is exacerbated by the development of antibiotic resistance. In this study, we investigated the incidence of known virulence determinants in starter, food, and medical strains of Enterococcus faecalis, E. faecium, and E. durans. PCR and gene probe strategies were used to screen enterococcal isolates from both food and medical sources. Different and distinct patterns of incidence of virulence determinants were found for the E. faecalis and E. faecium strains. Medical E. faecalis strains had more virulence determinants than did food strains, which, in turn, had more than did starter strains. All of the E. faecalis strains tested possessed multiple determinants (between 6 and 11). E. faecium strains were generally free of virulence determinants, with notable exceptions. Significantly, esp and gelE determinants were identified in E. faecium medical strains. These virulence determinants have not previously been identified in E. faecium strains and may result from regional differences or the evolution of pathogenic E. faecium. Phenotypic testing revealed the existence of apparently silent gelE and cyl genes. In E. faecalis, the trend in these silent genes mirrors that of the expressed determinants. The potential for starter strains to acquire virulence determinants by natural conjugation mechanisms was investigated. Transconjugation in which starter strains acquired additional virulence determinants from medical strains was demonstrated. In addition, multiple pheromone-encoding genes were identified in both food and starter strains, indicating their potential to acquire other sex pheromone plasmids. These results suggest that the use of Enterococcus spp. in foods requires careful safety evaluation.     

Virulence factors and<Emphasis Type="Italic">in Vitro</Emphasis> adherence of<Emphasis Type="Italic">Enterococcus</Emphasis> strains to urinary catheters

The ability to adhere in vitro to urinary catheters and the presence of enterococcal virulence factors was determined in 30 Enterococcus urinary isolates (12 E. faecalis, 12 E. faecium, 3 E. casseliflavus, 3 E. gallinarum). Silicone, siliconized latex and polyvinyl chloride (PVC) were examined by sonication quantitative culture technique and scanning electron microscope. As compared to E. faecalis and E. faecium, E. casseliflavus and E. gallinarum displayed lower adhesion to all synthetic materials. All the tests performed showed higher adherence of all tested strains to siliconized latex and silicone than to PVC. Biofilmforming ability was observed in 5 E. faecalis but in none of the remaining strains. The gene coding enterococcal surface protein (Esp) was detected in 7 E. faecalis and 6 E. faecium strains. Gelatinase was found in 1 E. faecalis, 2 E. faecium and hemolysins were found in 6 E. faecalis and 1 E. faecium strains. All E. casseliflavus and E. gallinarum strainswere negative for these traits. Hydrophobic type of cell surface (measured by its affinity for n-hexadecane) was shown in a few isolates. Bacterial adherence was not significantly associated with the above pathogenic factors.     

Genetic diversity and safety aspects of enterococci from slightly fermented sausages

AIMS: To determine the biodiversity of enterococci from slightly fermented sausages (chorizo and fuet) at species and strain level by molecular typing, while considering their safety aspects. METHODS AND RESULTS: Species-specific PCR and partial sequencing of 16S rRNA and sodA genes were used to identify enterococcal population. Enterococcus faecium was the most frequently isolated species followed by E. faecalis, E. hirae and E. durans. Randomly amplified polymorphic DNA (RAPD)-PCR revealed species-specific clusters and allowed strain typing. Sixty strains of 106 isolates exhibited different RAPD profiles indicating a high genetic variability. All the E. faecalis strains carried virulence genes (efaAfs, esp, agg and gelE) and all E. faecium isolates carried efaAfm gene. Enterococcus faecalis showed higher antibiotic resistance than the other species. Only one E. faecium strain showed vanA genotype (high-level resistance to glycopeptides) and E. gallinarum and E. casseliflavus/flavescens isolates showed vanC1 and vanC2/C3 genotypes (low-level resistance only to vancomycin) respectively. CONCLUSIONS: E. faecalis has been mainly associated with virulence factors and antimicrobial multi-resistance and, although potential risk for human health is low, the presence of this species in slightly fermented sausages should be avoided to obtain high quality products. SIGNIFICANCE AND IMPACT OF THE STUDY: The enterococcal population of slightly fermented sausages has been thoroughly characterized. Several relevant safety aspects have been revealed.     

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.     

Comparison of genotypic and phenotypic cluster analyses of virulence determinants and possible role of CRISPR elements towards their incidence in Enterococcus faecalis and Enterococcus faecium

Enterococcus faecalis and Enterococcus faecium are human commensals frequently found in fermented foods or used as probiotics, but also recognized as opportunistic pathogens. We investigated 62 Enterococcus strains isolated from clinical, food and environmental origins towards a rationale for safety evaluation of strains in food or probiotic applications. All isolates were characterised with respect to the presence of the virulence determinants fsrB, sprE, gelE, ace, efaAfs/fm, as, esp, cob and the cytolysin operon. In addition RAPD-PCR was used to obtain genomic fingerprints that were clustered and compared to phenotypic profiles generated by MALDI-TOF-MS. The gelatinase phenotype (GelE) and the haemolytic activity (β-haemolysis) were analysed. E. faecium strains contained esp and efaAfm only, and none of them contained any CRISPR elements. The amenability of E. faecalis strains to acquisition of virulence factors was investigated along the occurrence of CRISPR associated (cas) genes. While distribution of most virulence factors, and RAPD versus MALDI-TOF-MS typing patterns were unrelated, 2 out of 5 RAPD clusters almost exclusively contained clinical E. faecalis isolates, and an occurrence of CRISPR elements versus reduced number of virulence factors was observed. The presence of the cytolysin operon, cob and as encoding pheromone and aggregation substance, respectively, significantly corresponded to absence of cas. As their production promote genetic exchange, their absence limits further gene acquisition and distribution. Thus, absence of the cytolysin operon, cob and as in a cas positive environment suggests itself as promising candidate for E. faecalis evaluation towards their occurrence in food fermentation or use as probiotics.     

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.     

Galleria mellonella as a model for studying Enterococcus faecium host persistence

Enterococcus faecium is an opportunistic pathogen responsible for numerous outbreaks worldwide. The basis for the colonization capacities, host persistence and environmental stress response of the hospital-adapted clones emerging from E. faecium are poorly understood. In this study, we propose the use of Galleria mellonella as a simple nonmammalian model to assess E. faecium host persistence. Various strains (n = 10), including hospital-adapted, commensal or animal isolates and a SodA-deficient strain were used to assess the relevance of this model. Compared to Enterococcus faecalis, E. faecium strains do not appear very lethal in a Galleria killing assay. The ability of E. faecium strains to overcome host-immune responses and multiply within the host system was evaluated by monitoring bacterial loads following Galleria infection. Among the E. faecium strains, two hospital-adapted isolates displayed increased colonization ability. In contrast, inactivation of sodA, encoding a putative manganese-dependent superoxide dismutase, significantly reduced survival of E. faecium to Galleria defenses. Galleria appears to be a suitable and convenient surrogate model to study E. faecium survival to host defenses and the role of suspected virulence factors in the colonization process.     

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.     

Detection of virulence factors in high-level gentamicin-resistant Enterococcus faecalis and Enterococcus faecium isolates from a Tunisian hospital

Phenotypic and genotypic determination of virulence factors were carried out in 46 high-level gentamicin-resistant (HLGR) clinical Enterococcus faecalis (n=34) and Enterococcus faecium (n=12) isolates recovered from different patients in La Rabta Hospital in Tunis, Tunisia, between 2000 and 2003 (all these isolates harboured the aac(6')-aph(2") gene). The genes encoding virulence factors (agg, gelE, ace, cylLLS, esp, cpd, and fsrB) were analysed by PCR and sequencing. The production of gelatinase and hemolysin, the adherence to caco-2 and hep-2 cells, and the capacity for biofilm formation were investigated in all 46 HLGR enterococci. The percentages of E. faecalis isolates harbouring virulence genes were as follows: gelE, cpd, and ace (100%); fsrB (62%); agg (56%); cylLLS (41.2%); and esp (26.5%). The only virulence gene detected among the 12 HLGR E. faecium isolates was esp (58%). Gelatinase activity was detected in 22 of the 34 E. faecalis isolates (65%, most of them with the gelE+-fsrB+ genotype); the remaining 12 isolates were gelatinase-negative (with the gelE+-fsrB- genotype and the deletion of a 23.9 kb fragment of the fsr locus). Overall, 64% of the cylLLS-containing E. faecalis isolates showed beta-hemolysis. A high proportion of our HLGR E. faecalis isolates, in contrast to E. faecium, showed moderate or strong biofilm formation or adherence to caco-2 and hep-2 cells.     

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.     

Molecular identification and diversity of enterococci isolated from Slovak Bryndza cheese

Three hundred and eight presumed enterococcal isolates were recovered from Bryndza, a soft sheep milk cheese. The cheese samples were obtained from five different commercial distributors in Slovakia and were taken at three different seasonal intervals. All isolates were identified to the species level using genotypic tools. Species-specific PCR using ddl genes highlighted the predominance of Enterococcus faecium (176 isolates) and assigned 50 isolates to the species Enterococcus faecalis. The remaining 82 isolates were classified using repetitive element sequence-based polymerase chain reaction (PCR) with primer (GTG)(5)-(GTG)(5)-PCR, in combination with phenylalanyl-tRNA synthase gene (pheS) sequence analysis and by whole-cell protein analysis (SDS-PAGE). These strains were identified as Enterococcus durans (59 strains), Enterococcus italicus (8 strains), Enterococcus casseliflavus (3 strains), Enterococcus gallinarum (3 strains), Enterococcus hirae (1 strain), and 8 strains were members of the species Lactococcus lactis. Of the seven enterococcal species isolated, three of them, E. durans, E. faecalis and E. faecium were present in all samples studied, with E. faecium as the predominant one. The precise identification of enterococci in Bryndza cheese is an essential step in the process of evaluation of their functional properties which will be further studied and assessed.     

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。     

Dogs leaving the ICU carry a very large multi-drug resistant enterococcal population with capacity for biofilm formation and horizontal gene transfer

The enterococcal community from feces of seven dogs treated with antibiotics for 2-9 days in the veterinary intensive care unit (ICU) was characterized. Both, culture-based approach and culture-independent 16S rDNA amplicon 454 pyrosequencing, revealed an abnormally large enterococcal community: 1.4±0.8×10(8) CFU gram(-1) of feces and 48.9±11.5% of the total 16,228 sequences, respectively. The diversity of the overall microbial community was very low which likely reflects a high selective antibiotic pressure. The enterococcal diversity based on 210 isolates was also low as represented by Enterococcus faecium (54.6%) and Enterococcus faecalis (45.4%). E. faecium was frequently resistant to enrofloxacin (97.3%), ampicillin (96.5%), tetracycline (84.1%), doxycycline (60.2%), erythromycin (53.1%), gentamicin (48.7%), streptomycin (42.5%), and nitrofurantoin (26.5%). In E. faecalis, resistance was common to tetracycline (59.6%), erythromycin (56.4%), doxycycline (53.2%), and enrofloxacin (31.9%). No resistance was detected to vancomycin, tigecycline, linezolid, and quinupristin/dalfopristin in either species. Many isolates carried virulence traits including gelatinase, aggregation substance, cytolysin, and enterococcal surface protein. All E. faecalis strains were biofilm formers in vitro and this phenotype correlated with the presence of gelE and/or esp. In vitro intra-species conjugation assays demonstrated that E. faecium were capable of transferring tetracycline, doxycycline, streptomycin, gentamicin, and erythromycin resistance traits to human clinical strains. Multi-locus variable number tandem repeat analysis (MLVA) and pulsed-field gel electrophoresis (PFGE) of E. faecium strains showed very low genotypic diversity. Interestingly, three E. faecium clones were shared among four dogs suggesting their nosocomial origin. Furthermore, multi-locus sequence typing (MLST) of nine representative MLVA types revealed that six sequence types (STs) originating from five dogs were identical or closely related to STs of human clinical isolates and isolates from hospital outbreaks. It is recommended to restrict close physical contact between pets released from the ICU and their owners to avoid potential health risks.     

Molecular characterization of enterococci harboring genotype and phenotype incongruence related to glycopeptide resistance isolated in Brazilian hospitals

Three Enterococcus faecalis and one Enterococcus faecium strains were characterized by plasmid profile, pulsed-field gel electrophoresis (PFGE) and determination of antimicrobial minimal inhibitory concentrations. VanA elements were characterized by Long PCR, overlapping PCR and DNA sequencing. Enterococcal strains showed resistance to vancomycin and harbored the vanA gene, and three these were teicoplanin susceptible while one showed intermediate resistance to teicoplanin. Two E. faecalis strains showed indistinguishable PFGE profile while the third was unrelated. E. faecalis strains showed a deletion in the right terminal region of the Tn1546-like element. The E. faecium strain showed an insertion element in the vanXY intergenic region. Mutations in VanA elements were not found. Rearrangements in the VanA element could be responsible for incongruities in genotype and phenotype in these strains.     

VanA-type enterococci from humans, animals, and food: species distribution, population structure, Tn1546 typing and location, and virulence determinants

VanA-type human (n=69), animal (n=49), and food (n=36) glycopeptide-resistant enterococci (GRE) from different geographic areas were investigated to study their possible reservoirs and transmission routes. Pulsed-field gel electrophoresis (PFGE) revealed two small genetically related clusters, M39 (n=4) and M49 (n=13), representing Enterococcus faecium isolates from animal and human feces and from clinical and fecal human samples. Multilocus sequence typing showed that both belonged to the epidemic lineage of CC17. purK allele analysis of 28 selected isolates revealed that type 1 was prevalent in human strains (8/11) and types 6 and 3 (14/15) were prevalent in poultry (animals and meat). One hundred and five of the 154 VanA GRE isolates, encompassing different species, origins, and PFGE types, were examined for Tn1546 type and location (plasmid or chromosome) and the incidence of virulence determinants. Hybridization of S1- and I-CeuI-digested total DNA revealed a plasmid location in 98% of the isolates. Human intestinal and animal E. faecium isolates bore large (>150 kb) vanA plasmids. Results of PCR-restriction fragment length polymorphism and sequencing showed the presence of prototype Tn1546 in 80% of strains and the G-to-T mutation at position 8234 in three human intestinal and two pork E. faecium isolates. There were no significant associations (P>0.5) between Tn1546 type and GRE source or enterococcal species. Virulence determinants were detected in all reservoirs but were significantly more frequent (P<0.02) among clinical strains. Multiple determinants were found in clinical and meat Enterococcus faecalis isolates. The presence of indistinguishable vanA elements (mostly plasmid borne) and virulence determinants in different species and PFGE-diverse populations in the presence of host-specific purK housekeeping genes suggested that all GRE might be potential reservoirs of resistance determinants and virulence traits transferable to human-adapted clusters.     

Drug sensitivity of Enterococcus sp. strains isolated from clinical material or from healthy persons

The aim of this study was to evaluate the drug susceptibility of Enterococcus sp. strains isolated in 2000-2001, from patients of five Warsaw's hospitals (154 strains) and from fecal samples of healthy persons (33 strains). On biochemical reaction profiles species of clinical enterococci were identified as: E. faecalis--66.2%, E. faecium--29.2%, E. hirae--1.9%, E. gallinarum--1.3%, E. casseliflavus--0.6% and E. avium--0.6%. The species of enterococci from stool's samples were identified as: E. faecalis--28 strains, E. durans--2 strains and single strains: E. faecium, E. gallinarum and E. casseliflavus. Susceptibility to 20 antibiotics was tested by disc diffusion method. None of these 187 enterococcal strains was vancomycin resistant; 3 strains of E. gallinarum and 1--E. casseliflavus demonstrated intermediately susceptibility to vancomycin, but they were susceptible to teicoplanin--phenotype Van C. Among clinical strains were resistant to penicillin--33.3% of E. faecalis and 100% of E. faecium, to ampicillin--over 80% of E. faecium and 1 strain of E. faecalis. None of these strains produced beta-lactamase. High-level resistance to aminoglicoside was expressed by 48 strains (47.1%) E. faecalis and 36 (80%) E. faecium isolated from clinical specimens. Both--HLR to streptomycin and gentamycin were found in 28.3% of E. faecalis and 68.9% of E. faecium. Among 33 strains isolated from fecal samples of healthy persons--3 of E. faecalis were resistant to streptomycin and one was resistant to both gentamicin and streptomycin. In general, enterococcal strains isolated from samples of healthy persons were susceptible to the most of used antibiotics. But to rifampicin none of these strains were susceptible. There were about 40% of E. faecalis strains isolated from healthy persons, resistant to tetracyline.     

临床分离肠球菌的耐药性研究

目的了解近3年来粤东地区临床分离的肠球菌的耐药特征,为预防耐万古霉素肠球菌（VRE）的产生和控制VRE播散提供理论依据和实验基础。方法收集临床分离的215株肠球菌,细菌鉴定及药敏试验采用VITEK-60全自动细菌鉴定仪。结果215株肠球菌中,尿标本中分离肠球菌75株（35％）;痰液中分离出34株（16％）。粪肠球菌141株（65．5％）,屎肠球菌74株（34．5％）。粪肠球菌对万古霉素、呋喃妥因、青霉素G和莫西沙星的敏感率较高,70％～100％;对红霉素和四环素的敏感性较差,11％～33％。屎肠球菌对万古霉素敏感性较好为100％,四环素为62％;而对呋喃妥因、高链霉素、青霉素和左氧氟沙星等敏感性较差（5％～47％）。未检出耐万古霉素肠球菌。结论粤东地区近3年来未发现耐万古霉素肠球菌。肠球菌对各种常见抗生素敏感程度呈下降趋势。屎肠球菌较粪肠球菌耐药性更高。应根据细菌学培养结果合理用药,减少耐药菌株的发生率。