Identification of Tn5397-like and Tn916-like transposons and diversity of the tetracycline resistance gene tet(M) in enterococci from humans, pigs and poultry

OBJECTIVES: To analyse the sequence diversity of the tetracycline resistance gene tet(M) and its location on mobile elements in Enterococcus faecium and Enterococcus faecalis from humans, pigs and poultry in Denmark. METHODS: A total of 76 isolates were screened for Tn916/Tn1545-like and Tn5397-like transposons using PCR. tet(M) was sequenced in 15 of the isolates and compared with tet(M) sequences submitted to GenBank (phylogenetic analysis and signs of recombination). Plasmids were extracted, filter-mating experiments were performed and Tn5397-like transposons were further characterized in selected isolates. RESULTS: In 8 of 13 isolates of E. faecium from broilers, tet(M) was present on Tn5397-like transposons, whereas tet(M) was predominantly associated with Tn916/Tn1545-like transposons in E. faecium from pigs and humans, as well as in E. faecalis from humans, pigs and broilers (50 of 63 isolates). The tet(M) genes were divided into three major subgroups according to the phylogenetic analysis. Subgroup I consisted of tet(M) from Clostridium difficile and E. faecium associated with Tn5397-like elements, subgroup II consisted of tet(M) located on Tn916/Tn1545 family transposons and subgroup III consisted of tet(M) associated with composite elements containing several resistance genes. We found evidence of recombination both within and between these groups. Moreover, we identified an E. faecium isolate with both Tn916/Tn1545-like and Tn5397-like elements. CONCLUSIONS: This study showed that enterococci contain diverse tet(M) genes present on different mobile elements, which may suggest that enterococci play an important role in the evolution and horizontal spread of mobile elements carrying tet(M). This is the first report of Tn5397-like elements in enterococci.     

271株肠球菌属细菌的分布和耐药性分析

目的了解内蒙古鄂尔多斯市中心医院临床分离的肠球菌属细菌的分布情况及对各类抗菌药物的耐药性。方法使用VITEK 2 compact全自动细菌检测分析系统对2010年1月至2013年6月从临床标本中分离的271株肠球菌属细菌进行菌种鉴定和药敏试验,并用WHONET5．6软件对结果进行统计分析。结果271株肠球菌属细菌中,屎肠球菌137株（50．6％）,粪肠球菌80株（29．5％）,其他肠球菌54株（19．9％）。肠球菌属细菌主要分离自尿液69株（25．5％）、脓液40株（14．8o,4）、伤口等分泌物34株（12．5％）。粪肠球菌对万古霉素和利奈唑胺的耐药率分别为1．3％和1．5％;未检出呋喃妥因耐药株;对青霉素和氨苄西林的耐药率较低,分别为11．8％和2．6％;对高浓度庆大霉素和高浓度链霉素的耐药率分别为31．0％和22．9％。屎肠球菌的耐药率明显高于粪肠球菌,对万古霉素的耐药率为4．4％,未检出利奈唑胺耐药株,对呋喃妥因的耐药率为19．1％;对高浓度庆大霉素和高浓度链霉素的耐药率分别为44．8％和26．4％;但对四环素和奎奴普丁一达福普汀的耐药率低于粪肠球菌,分别为58．3％和0。结论屎肠球菌对抗菌药物的耐药率较粪肠球菌高;并已出现对万古霉素耐药株;其耐药性存在地区和菌种间差异,临床治疗应根据细菌药敏结果合理选用抗菌药物。     

Glycopeptide susceptibility among Danish Enterococcus faecium and Enterococcus faecalis isolates of animal and human origin and PCR identification of genes within the VanA cluster.

The MICs of vancomycin and avoparcin were determined for isolates of Enterococcus faecium and isolates of Enterococcus faecalis recovered from the feces of humans and animals in Denmark. Two hundred twenty-one of 376 (59%) isolates of E. faecium and 2 of 133 (1.5%) isolates of E. faecalis were resistant to vancomycin (MICs, 128 to > or = 256 micrograms/ml), and all vancomycin-resistant isolates were resistant to avoparcin (MICs, 64 to > or = 256 micrograms/ml). All vancomycin-resistant isolates examined carried the vanA, vanX, and vanR genes, suggesting that a gene cluster similar to that of the transposon Tn1546 was responsible for the resistance.     

Effect of abolishment of the use of antimicrobial agents for growth promotion on occurrence of antimicrobial resistance in fecal enterococci from food animals in Denmark.

From 1995 to 2000, a total of 673 Enterococcus faecium and 1,088 Enterococcus faecalis isolates from pigs together with 856 E. faecium isolates from broilers were isolated and tested for susceptibility to four classes of antimicrobial agents used for growth promotion as part of the Danish program of monitoring for antimicrobial resistance. The four antimicrobials were avilamycin, erythromycin, vancomycin, and virginiamycin. Major changes in the use of antimicrobial agents for growth promotion have occurred during the last 6 years in Denmark. The government banned the use of avoparcin in 1995 and of virginiamycin in 1998. Furthermore, the producers have voluntarily stopped all use beginning in 1999. The avoparcin ban in 1995 was followed by a decrease in the occurrence of glycopeptide-resistant E. faecium (GRE) in broilers, from 72.7% in 1995 to 5.8% in 2000. The occurrence of glycopeptide resistance among isolates from pigs remained constant at around 20% from 1995 to 1997. It was shown that, in GRE from pigs, the genes encoding macrolide and glycopeptide resistance were genetically linked and that, following the decrease in the use of tylosin during 1998 and 1999, the occurrence of GRE in pigs decreased to 6.0% in 2000. From 1995 to 1997 the occurrence of erythromycin resistance among E. faecium and E. faecalis isolates from pigs was almost 90%. Use of tylosin decreased considerably during 1998 and 1999, and this decrease was followed by decreases in the occurrence of resistance to 46.7 and 28.1% among E. faecium and E. faecalis isolates from pigs, respectively. Erythromycin resistance among E. faecium isolates from broilers reached a maximum of 76.3% in 1997 but decreased to 12.7% in 2000 concomitantly with more limited use of virginiamycin. Use of virginiamycin increased from 1995 to 1997 and was followed by an increased occurrence of virginiamycin resistance among E. faecium isolates in broilers, from 27.3% in 1995 to 66.2% in 1997. In January 1998 the use of virginiamycin was banned in Denmark, and the occurrence of virginiamycin resistance decreased to 33.9% in 2000. Use of avilamycin increased from 1995 to 1996 and was followed by an increase in avilamycin resistance among E. faecium isolates from broilers, from 63.6% in 1995 to 77.4% in 1996. Since 1996 avilamycin usage has decreased, followed by a decrease in resistance to 4.8% in 2000. Our observations show that it is possible to reduce the occurrence of antimicrobial resistance in a national population of food animals when the selective pressure is removed. Cases in which resistance to vancomycin was linked to resistance to erythromycin were exceptions. In such cases resistance did not decrease until the use of both avoparcin and tylosin was limited.     

儿童患者中肠球菌属临床分离株耐药特征分析

目的了解儿童患者临床分离肠球菌属的耐药特征，指导临床合理用药。方法测定11种抗菌药物对158株肠球菌的MIC，Nithocefin纸片法检测B内酰胺酶，数据用WHONET5．3软件分析处理。结果158株儿童临床分离肠球菌中，粪肠球菌、屎肠球菌、坚韧肠球菌、鸟肠球菌和海氏肠球菌分别占56．3％、39．9％、1．3％、1．3％和1．3％；屎肠球菌对氨苄西林、阿莫西林-克拉维酸和环丙沙星的耐药率分别为96．8％，95，2％和84．1％，粪肠球菌对上述3种抗菌药的耐药率分别为23．6％，18％和49，4％，屎肠球菌的耐药率明显高于粪肠球菌（P〈20，001）；粪肠球菌出现2株万古霉素MIC为8mg／L的耐药菌，粪肠球菌和屎肠球菌对替考拉宁全部敏感。儿童患者中多重耐药肠球菌属菌株占88．6％。结论儿童患者肠球菌属的耐药状况十分严重，尤其屎肠球菌对B内酰胺类、氨基糖苷类和氟喹诺酮类抗菌药耐药率很高。     

2007-2012年浙江萧山医院尿路感染患者的肠球菌分布及耐药性分析

目的 调查从尿路感染患者分离的肠球菌的菌种、临床分布及耐药性,为临床合理选用抗生素提供依据。方法 尿培养采用经典型浸片Uricult,ATB-Expression细菌分析系统进行鉴定和药敏试验;所有资料采用Whonet 5.6软件进行回顾性分析。结果 分离肠球菌238株,主要为粪肠球菌122株（51.3%）和屎肠球菌95株（39.9%）;菌株主要来源列前2位的是内科（38.2%）和泌尿外科（21.0%）;耐药率较高的是红霉素（86.5%）、利福平（75.7%）和四环素（66.4%）;较低的是呋喃妥因（19.7%）、万古霉素（9.6%）和利奈唑胺（0.0%）;粪肠球菌对利福平、红霉素、奎奴普丁/达福普汀和四环素的耐药率较高,均76.5%,万古霉素耐药率0.9%;屎肠球菌对氨苄西林等8种药物耐药率75.8%,万古霉素耐药率4.3%。粪肠球菌对所测试抗生素耐药率仅有四环素、奎奴普丁/达福普汀高于屎肠球菌,其余低于屎肠球菌;利福平、万古霉素和利奈唑胺耐药率在二者间差异无统计学意义。2007年与2012年相比,青霉素、氨苄西林等药物耐药率上升,而环丙沙星、四环素等下降。结论 肠球菌是引起尿路感染的重要病原菌,以粪肠球菌和屎肠球菌为主,不同种类肠球菌耐药率差别较大,加强细菌培养和定期分析其耐药性,有助于提高临床治愈率及合理用药水平。     

High-level vancomycin-resistant Staphylococcus aureus isolates associated with a polymicrobial biofilm

Glycopeptides such as vancomycin are the treatment of choice for infections due to methicillin-resistant Staphylococcus aureus. This study describes the identification of high-level vancomycin-resistant S. aureus (VRSA) isolates in a polymicrobial biofilm within an indwelling nephrostomy tube in a patient in New York. S. aureus, Enterococcus faecalis, Enterococcus faecium, Micrococcus species, Morganella morganii, and Pseudomonas aeruginosa were isolated from the biofilm. For VRSA isolates, vancomycin MICs ranged from 32 to >128 microg/ml. VRSA isolates were also resistant to aminoglycosides, fluoroquinolones, macrolides, penicillin, and tetracycline but remained susceptible to chloramphenicol, linezolid, rifampin, and trimethoprim-sulfamethoxazole. The vanA gene was localized to a plasmid of approximately 100 kb in VRSA and E. faecium isolates from the biofilm. Plasmid analysis revealed that the VRSA isolate acquired the 100-kb E. faecium plasmid, which was then maintained without integration into the MRSA plasmid. The tetracycline resistance genes tet(U) and tet(S), not previously detected in S. aureus isolates, were identified in the VRSA isolates. Additional resistance elements in the VRSA isolate included a multiresistance gene cluster, ermB-aadE-sat4-aphA-3, msrA (macrolide efflux), and the bifunctional aminoglycoside resistance gene aac(6')-aph(2")-Ia. Multiple combinations of resistance genes among the various isolates of staphylococci and enterococci, including vanA, tet(S), and tet(U), illustrate the dynamic nature of gene acquisition and loss within and between bacterial species throughout the course of infection. The potential for interspecies transfer of antimicrobial resistance genes, including resistance to vancomycin, may be enhanced by the microenvironment of a biofilm.     

2010年中国CHINET肠球菌属细菌耐药性监测

目的了解2010年中国主要地区临床分离肠球菌属细菌对各类抗菌药物的耐药性。方法国内主要地区14所教学医院(12所综合性医院,2所儿童医院)按统一方案、采用统一的材料、方法(K-B法)和判断标准(CLSI 2010年版)进行肠球菌属细菌的耐药性监测。结果共分离到4 046株非重复肠球菌属细菌,最常见菌种为粪肠球菌1 829株(45.2%)、屎肠球菌1 817株(44.9%)、鹑鸡肠球菌78株(1.9%)、鸟肠球菌54株(1.3%)、铅黄肠球菌49株(1.2%)。肠球菌属对利奈唑胺、万古霉素、替考拉宁仍极敏感,耐药率<4%,万古霉素耐药粪肠球菌和屎肠球菌检出率分别为0.6%、3.6%。粪肠球菌对呋喃妥因、磷霉素和氨苄西林耐药率较低,分别为3.2%、5.7%和11.3%,对高浓度庆大霉素耐药率为44.0%;屎肠球菌耐药性明显高于粪肠球菌,对氨苄西林耐药率接近90%,对高浓度庆大霉素耐药率接近70%,对氯霉素耐药率仅为7.3%,儿童屎肠球菌分离株对磷霉素、呋喃妥因耐药率<10%。不同医院分离的肠球菌属细菌对抗菌药物的耐药率有一定差异。结论屎肠球菌的分离率有增加趋势,肠球菌属细菌对利奈唑胺、万古霉素、替考拉宁依然保持极高的敏感性。     

A clonal lineage of VanA-type Enterococcus faecalis predominates in vancomycin-resistant Enterococci isolated in New Zealand

Avoparcin was used as a feed additive in New Zealand broiler production from 1977 until June 2000. We report here on the effects of the usage and discontinuation of avoparcin on the prevalence of vancomycin-resistant enterococci (VRE) in broilers. Eighty-two VRE isolates were recovered from poultry fecal samples between 2000 and mid-2001. VRE isolates were only obtained from broiler farms that were using, or had previously used, avoparcin as a dietary supplement. Of these VRE isolates, 73 (89%) were VanA-type Enterococcus faecalis and nine (11%) were VanA-type Enterococcus faecium. All E. faecalis isolates were found to have an identical or closely related pulsed-field gel electrophoresis (PFGE) pattern of SmaI-digested DNA and were susceptible to both ampicillin and gentamicin. The PFGE patterns of the nine E. faecium isolates were heterogeneous. All VRE contained both the vanA and ermB genes, which, regardless of species or PFGE pattern, resided on the same plasmid. Eighty-seven percent of the VRE isolates also harbored the tet(M) gene, while for 63 and 100%, respectively, of these isolates, the avilamycin and bacitracin MICs were high (>or=256 microg/ml). Five of eight vancomycin-resistant E. faecalis isolates recovered from humans in New Zealand revealed a PFGE pattern identical or closely related to that of the E. faecalis poultry VRE isolates. Molecular characterization of Tn1546-like elements from the VRE showed that identical transposons were present in isolates from poultry and humans. Based on the findings presented here, a clonal lineage of VanA-type E. faecalis dominates in VRE isolated from poultry and humans in New Zealand.     

2015年重庆市粪肠球菌和屎肠球菌耐药性监测结果分析

目的 统计分析2015年重庆市细菌耐药监测网成员单位提交的粪肠球菌和屎肠球菌耐药性监测数据,为该市有效应用抗菌药物提供依据和参考.方法 各成员单位根据全国细菌耐药监测网技术方案要求,对目标细菌进行鉴定和药敏试验,并依据美国临床和实验室标准化协会(CLSI)2015版标准进行结果判读,使用WHONET5.6软件对药敏数据进行统计分析,耐药性差异采用SPSS21.0软件进行分析.结果 共分离到非重复粪肠球菌和屎肠球菌分别为1 811株和1 601株,共占所有阳性菌株的13.1%,两者对万古霉素的耐药性分别为0.5%和1.8%,对利奈唑胺的耐药率分别为2.5%和0.5%,均未发现对替加环素耐药的菌株.粪肠球菌对奎奴普丁/达福普汀的耐药性最高,为90.1%,对四环素的耐药率也高达78.8%,对高浓度庆大霉素的耐药率为43.0%,对青霉素、氨苄西林、呋喃妥因的耐药率均低于7.0%.除奎奴普丁/达福普汀和四环素外,屎肠球菌对其他药物的耐药率高于粪肠球菌(P<0.05).儿童和成人患者,以及重症监护病房(ICU)和非ICU患者分离株对部分药物的耐药率比较差异有统计学意义(P<0.05).结论 该市肠球菌感染主要病原菌是屎肠球菌和粪肠球菌,两者耐药性不同.做好耐药性监测有助于指导临床医生规范、有效使用抗菌药物.     

tcrB, a gene conferring transferable copper resistance in Enterococcus faecium: occurrence, transferability, and linkage to macrolide and glycopeptide resistance

A newly discovered gene, designated tcrB, which is located on a conjugative plasmid conferring acquired copper resistance in Enterococcus faecium, was identified in an isolate from a pig. The tcrB gene encodes a putative protein belonging to the CPx-type ATPase family with homology (46%) to the CopB protein from Enterococcus hirae. The tcrB gene was found in E. faecium isolated from pigs (75%), broilers (34%), calves (16%), and humans (10%) but not in isolates from sheep. Resistant isolates, containing the tcrB gene, grew on brain heart infusion agar plates containing up to 28 mM CuSO4 compared to only 4 mM for the susceptible isolates. Copper resistance, and therefore the presence of the tcrB gene, was strongly correlated to macrolide and glycopeptide resistance in isolates from pigs, and the tcrB gene was shown to be located on the same conjugative plasmid as the genes responsible for resistance to these two antimicrobial agents. The frequent occurrence of this new copper resistance gene in isolates from pigs, where copper sulfate is being used in large amounts as feed additive, suggests that the use of copper has selected for resistance.     

Identification of vat(E) in Enterococcus faecalis isolates from retail poultry and its transferability to Enterococcus faecium

Sixteen isolates of Enterococcus faecalis were recovered from retail poultry samples (seven chickens and nine turkeys) purchased from grocery stores in the greater Washington, D.C., area. PCR for known streptogramin resistance genes identified vat(E) in five E. faecalis isolates (three isolates from chickens and two isolates from turkeys). The vat(E) gene was transmissible on a ca. 70-kb plasmid, along with resistance to erythromycin, tetracycline, and streptomycin, by conjugation to E. faecalis and Enterococcus faecium recipient strains. DNA sequencing showed little variation between E. faecalis vat(E) genes from the chicken samples; however, one E. faecalis vat(E) gene from a turkey sample possessed 5 nucleotide changes that resulted in four amino acid substitutions. None of these substitutions in the vat(E) allele have previously been described. This is the first report of vat(E) in E. faecalis and its transferability to E. faecium, which indicates that E. faecalis can act as a reservoir for the dissemination of vat(E)-mediated streptogramin resistance to E. faecium.     

Prevalence of resistance to ampicillin,gentamicin and vancomycin in Enterococcus faecalis and Enterococcus faecium isolates from clinical specimens and use of antimicrobials in five Nordic hospitals

We determined the species distribution and prevalence of ampicillin resistance, high-level gentamicin resistance (HLGR) and vancomycin resistance among clinical enterococcal isolates from five Nordic laboratories (Bergen, Troms?, Uppsala, Aarhus and Reykjavik). Isolates represented three different groups: (i) all blood culture isolates from 1999; (ii) consecutive in-patient isolates (maximum 40); and (iii) consecutive outpatient isolates (maximum 40) collected during March to May 2000. Antimicrobial use data were collected at the national and hospital level. A high proportion (31.4%) of Enterococcus faecium was detected among blood culture isolates, in contrast to only 4.2% among isolates from outpatients. Ampicillin resistance was not found in Enterococcus faecalis, in contrast to 48.8% in E. faecium isolates. HLGR rates varied considerably between laboratories (1.1-27.6%). Acquired vancomycin resistance was not detected. There were no significant differences in the prevalences of HLGR between in-patient and outpatient isolates at individual hospitals. A cluster of clonally related ampicillin-resistant and HLGR E. faecium isolates was demonstrated in one of the hospitals. The lowest level of hospital antimicrobial use, the lowest proportion of E. faecium and the lowest prevalence of resistance were observed in Reykjavik. The study showed a relatively low level of resistance in enterococci, as compared with most European countries and the USA. However, there were large differences between hospitals with regard to the relative proportion of E. faecium isolates, their susceptibility to ampicillin and gentamicin, as well as the prevalence of HLGR in E. faecalis isolates. This indicates a potential for further improvement of antibiotic policies, and possibly hospital infection control, to maintain the low resistance levels observed in these countries.     

Antibiotic resistance of enterococci isolated at a teaching hospital in Kuwait

Enterococci isolated in a teaching hospital were studied for their resistance to different antibiotics. Minimum inhibitory concentrations to high-level aminoglycosides and glycopeptide antibiotics were determined by agar dilution and E-test methods respectively. Genes encoding aminoglycoside-modifying enzymes were detected by the polymerase chain reaction (PCR). 195 enterococci were isolated from urines (54.3%), wounds (16.4%), blood (10.2%), and miscellaneous sources (18.9%). They consisted of E. faecalis (88.7%), E. faecium (9.2%), E. casseliflavus (1.5%) and E. bovis (0.5%). None of the enterococci produced penicillinase but 3.5% of them were resistant to ampicillin. They were also resistant to high-level gentamicin (15.9%), kanamycin (22.0%), streptomycin (21.0%), tetracycline (65.1%), erythromycin (62.6%), ciprofloxacin (36.1%), chloramphenicol (26.1%), vancomycin (3.0%) and teicoplanin (2.0%). Most of the high-level aminoglycoside-resistant isolates contained genes coding the bifunctional aminoglycoside modifying enzymes AAC(6')-APH(2"), APH(3') and ANT(6') but not the ANT(4') enzyme. The results demonstrated a low prevalence of vancomycin resistance among Enterococci in this hospital.     

Molecular characterization of multidrug-resistant Enterococcus spp. from poultry and dairy farms: detection of virulence and vancomycin resistance gene markers by PCR

Thirty multidrug-resistant Enterococcus spp. strains, including two from the milk of cows with mastitis, nine from chicken litter and 19 from turkey litter, were isolated. Twenty-five were identified by biochemical methods as E. gallinarum and five as E. faecalis. Most of the isolates were resistant to vancomycin, gentamicin, streptomycin, tetracycline, erythromycin, bacitracin, kanamycin and nalidixic acid but sensitive to ciprofloxacin, sulfamethoxazole, chloramphenicol, ampicillin and ofloxacin. Attempts were made by partial amplification of the gene sequences to detect the vancomycin resistance markers vanA (734-bp), vanB (420-bp), vanC1 (531-bp), and vanC2-C3 (673-bp); virulence markers cylA (427-bp) and cylB (225-bp) for enterococcal cytolysin and a biofilm-forming surface protein (Esp). Individual and multiplex-PCR assays for vancomycin resistance markers revealed the vanC1 gene in 22 E. gallinarum strains. None of the remaining isolates including five E. faecalis strains (MIC=2 microg ml(-1)) and three E. gallinarum strains (MIC=8 microg ml(-1)) had any of the van genes tested. Analysis by pulsed-field gel electrophoresis (PFGE) and a comparison of smaI banding profiles showed 11 different patterns. Probing with a DIG-labeled vanC1 PCR product indicated a common 38.0 kb SmaI DNA fragment in all the E. gallinarum strains harboring the vanC1 gene. The genes cylA and cylB were detected only in one clinical E. gallinarum isolate and two quality control clinical strains of E. faecalis (ATCC 51299 and 29212). None of the virulence factors were found in milk or poultry isolates. Intermediate level resistance to vancomycin in enterococci from the US animal farms was predominantly due to the presence of vanC1 gene.     

Bacteriocin production in vancomycin-resistant and vancomycin-susceptible Enterococcus isolates of different origins

Bacteriocin production was determined for 218 Enterococcus isolates (Enterococcus faecalis [93] and E. faecium [125]) obtained from different origins (human clinical samples [87], human fecal samples [78], sewage [28], and chicken samples [25]) and showing different vancomycin susceptibility patterns (vancomycin resistant, all of them vanA positive [56], and vancomycin susceptible [162]). All enterococcal isolates were randomly selected except for the vancomycin-resistant ones. A total of 33 isolates of eight different bacterial genera were used as indicators for bacteriocin production. Forty-seven percent of the analyzed enterococcal isolates were bacteriocin producers (80.6% of E. faecalis and 21.6% of E. faecium isolates). The percentage of bacteriocin producers was higher among human clinical isolates (63.2%, 81.8% of vancomycin-resistant isolates and 60.5% of vancomycin-susceptible ones) than among isolates from the other origins (28 to 39.3%). Only one out of the 15 vancomycin-resistant isolates from human fecal samples was a bacteriocin producer, while 44.4% of fecal vancomycin-susceptible isolates were. The bacteriocin produced by the vanA-containing E. faecium strain RC714, named bacteriocin RC714, was further characterized. This bacteriocin activity was cotransferred together with the vanA genetic determinant to E. faecalis strain JH2-2. Bacteriocin RC714 was purified to homogeneity and its primary structure was determined by amino acid sequencing, showing an identity of 88% and a similarity of 92% with the previously described bacteriocin 31 from E. faecalis YI717. The presence of five different amino acids in bacteriocin RC714 suggest that this could be a new bacteriocin. The results obtained suggest that the epidemiology of vancomycin resistance may be influenced by different factors, including bacteriocin production.     

A gene conferring resistance to vancomycin but not teicoplanin in isolates of Enterococcus faecalis and Enterococcus faecium demonstrates homology with vanB, vanA, and vanC genes of enterococci.

We report the sequence of a 630-bp fragment of a gene associated with resistance to high levels of vancomycin in a clinical isolate of Enterococcus faecalis which retained susceptibility to teicoplanin. This gene was similar to the recently sequenced vanB and partially homologous with vanA, but it showed less-marked similarity to vanC. A DNA probe, derived from this polymerase chain reaction-amplified gene fragment, hybridized specifically with genomic DNA from Enterococcus faecium and E. faecalis isolates which were vancomycin resistant (MICs ranged from 8 to 512 micrograms/ml) but susceptible to teicoplanin. Curing of vancomycin resistance was associated with loss of DNA hybridization with the gene probe. Transfer of DNA which hybridized with the probe accompanied transfer of vancomycin resistance to a susceptible recipient strain. Neither curing nor transfer of vancomycin resistance was consistently related to loss or acquisition, respectively, of plasmid DNA.     

Macrolide resistance genes in Enterococcus spp

Seventy-eight isolates of different Enterococcus species (E. faecalis, n = 27; E. faecium, n = 23; E. durans, n = 8; E. avium, n = 6; E. hirae, n = 9; E. gallinarum, n = 3; and E. casseliflavus, n = 2) with a variety of erythromycin resistance phenotypes were examined for the presence of macrolide resistance genes (ermA, ermB, ermC, ermTR, mefA/E, and msrA). Positive PCR amplifications of ermB were obtained for 39 of 40 highly erythromycin-resistant Enterococcus isolates (MICs, >128 microg/ml) of different species; the remaining highly resistant E. faecium isolate was positive for PCR amplification of ermA but was negative for PCR amplification of the ermB and ermC genes. For all enterococcal strains for which erythromycin MICs were < or =32 microg/ml PCRs were negative for erm methylase genes. For all E. faecium isolates PCR amplified products of the expected size of 400 bp were obtained when msrA primers were used, with the results being independent of the erythromycin resistance phenotype. All the other enterococcal species gave negative results by msrA PCRs. Sequencing of the msrA PCR products from either erythromycin-susceptible, low-level-resistant, or highly resistant E. faecium strains showed that the amplicons did not correspond to the msrA gene described for Staphylococcus epidermidis but corresponded to a new putative efflux determinant, which showed 62% identity with the msrA gene at the DNA level and 72% similarity at the amino acid level. This new gene was named msrC.     

苏州市某三甲医院2017年临床分离菌耐药性监测

目的了解苏州大学附属第一医院2017年临床分离菌对临床常用抗菌药物的耐药性,为临床合理用药提供参考依据。方法采用纸片扩散法和自动化仪器进行细菌体外药敏试验,并用Whonet 5. 6软件进行统计分析。结果 2017年共分离9 106株非重复菌株,其中革兰阳性菌2 549株,占28. 0%,革兰阴性菌6 557株,占72. 0%。金黄色葡萄球菌(MRSA)和凝固酶阴性葡萄球菌中甲氧西林耐药株(MRCNS)的检出率分别为53. 8%和71. 6%。MRSA和MRCNS对绝大多数测试药物的耐药率均明显高于甲氧西林敏感株(MSSA和MSCNS)。MRSA中有94. 0%菌株对甲氧苄啶-磺胺甲唑敏感; MRCNS中有76. 4%的菌株对四环素敏感;未发现万古霉素耐药株。肠球菌属中粪肠球菌对多数测试抗菌药物(四环素除外)的耐药率均显著低于屎肠球菌,粪肠球菌检出1株利奈唑胺耐药株,屎肠球菌检出5株万古霉素耐药株。除肺炎克雷伯菌外,多数肠杆菌科细菌对碳青霉烯类抗生素仍高度敏感,耐药率低于6%。mCIM试验显示CR-KPN 99. 17%产碳青霉烯酶。结论临床分离菌耐药率呈增长性趋势,尤其是碳青霉烯类耐...     

Transferable vancomycin and teicoplanin resistance in Enterococcus faecium.

Enterococcus faecium BM4165 and BM4178, isolated from immunocompromised patients, one treated with vancomycin, were inducibly resistant to high levels of the glycopeptide antibiotics vancomycin and teicoplanin but susceptible to the new lipopeptide daptomycin (LY146032). Strain BM4165 was also resistant to macrolidelincosamide-streptogramin B-type (MLS) antibiotics. The genes conferring resistance to glycopeptides and to MLS antibiotics in strain BM4165 were carried on plasmids pIP819 and pIP821, respectively; pIP819 also carried genes that encoded resistance to MLS antibiotics. The two plasmids, which were distinct although related, were self-transferable to other E. faecium strains. Plasmid pIP819 could also conjugate to E. faecalis, Streptococcus sanguis, S. pyogenes, S. lactis, and Listeria monocytogenes, in which it conferred inducible glycopeptide resistance, but not to S. aureus. Glycopeptide-inactivating activity was not detected, and the biochemical mechanism of resistance remains unknown. Based on this first report of transferable resistance to glycopeptides, we anticipate dissemination of resistance to these antibiotics in gram-positive cocci and bacilli in which it can be phenotypically expressed.