Impact of LY146032 on Streptococcus (Enterococcus) faecalis translocation in mice.

The susceptibility of Swiss White mice to colonization with Streptococcus (Enterococcus) faecalis was greatly increased when the animals were given 5 mg of streptomycin sulfate per ml in their drinking water. One week after initiation of streptomycin treatment, the mice were challenged orogastrically with graded doses of streptomycin-resistant S. faecalis. The number of S. faecalis cells required to implant the intestinal tract of 50% of untreated mice was 2.9 X 10(9), but was only 4.8 X 10(3) for streptomycin-treated animals. When both groups of mice were challenged orogastrically with 4.6 X 10(6) viable S. faecalis cells, the cecum and small intestine of 100% of the streptomycin-treated animals, but only 10% of the untreated animals, were colonized with the organism. Similarly, translocation of S. faecalis to extraintestinal sites occurred in a majority of streptomycin-treated mice, but in only a small number of untreated mice. Subcutaneous administration of the experimental antibiotic LY146032 (Eli Lilly & Co., Indianapolis, Ind.) to streptomycin-treated mice concomitant with orogastric challenge with 5.5 X 10(5) viable S. faecalis cells resulted in a significant decrease in the incidence of intestinal colonization by the organism, a significant reduction in S. faecalis populations, and the absence of the organism in the liver, spleen, and heart. However, once intestinal colonization had occurred and extraintestinal infections were established, LY146032 did not significantly reduce S. faecalis populations or ameliorate the infections. We conclude that LY146032 effectively prevents translocation of S. faecalis from the intestinal tract of mice but does not resolve established extraintestinal infections.     

Enterococcal glycopeptide resistance at an Italian teaching hospital

Two thousand one hundred and thirteen strains of enterococci isolated at Pisa General Hospital in 1998 were analysed retrospectively to determine their glycopeptide resistance. Of all the microorganisms isolated in this period, 14.7% were enterococci (1405 Enterococcus faecalis, 19 Enterococcus faecium, six Enterococcus avium and 683 Enterococcus spp.). Two hundred and thirty (10.8%) of these enterococci were resistant or demonstrated reduced susceptibility to vancomycin and/or teicoplanin. The highest rate of resistance was found in outpatient enterococcal strains isolated from the urogenital tract. The frequency of enterococcal glycopeptide resistance at Pisa Hospital is higher than that reported from other areas of Italy.     

Effects of clindamycin and metronidazole on the intestinal colonization and translocation of enterococci in mice.

The intestinal colonization and translocation of enterococci was studied in mice treated intramuscularly with metronidazole or clindamycin, with or without oral streptomycin. Treatment with metronidazole resulted in selective elimination of strictly anaerobic cecal bacteria, with a 100-fold increase in the numbers of aerobic and facultative gram-negative bacilli and a 10,000-fold increase in the numbers of aerobic and facultative gram-positive species. Clindamycin had a similar effect on the cecal flora except that the numbers of aerobic and facultative gram-positive bacteria decreased at least 10-fold. The predominating gram-positive species in the cecal flora or metronidazole-treated mice was an enterococcus, but this organism could not be recovered from the ceca of clindamycin-treated mice. Translocating bacteria (primarily gram-negative enteric bacteria) were recovered from the mesenteric lymph nodes of the majority of mice given metronidazole or clindamycin. Gram-positive bacteria were not recovered from the mesenteric lymph nodes of 20 clindamycin-treated mice, whereas 26% of 19 metronidazole-treated mice had translocating enterococci. With addition of streptomycin to the metronidazole and clindamycin regimens, mice treated with metronidazole-streptomycin became colonized predominantly with an enterococcus, and this was the only translocating species recovered from 13% of 23 mice; however, enterococci could not be detected in the ceca of clindamycin-streptomycin-treated mice, and Bacillus spp. were recovered from the mesenteric lymph nodes of 8% of 24 mice, reflecting the composition of the cecal flora. The apparent elimination of enterococci from the ceca of clindamycin and clindamycin-streptomycin-treated mice was inconsistent with the observation that the average (n=6) peak levels of clindamycin in blood and ceca were 25 and 21 microgram/ml, respectively, whereas the in vitro MIC was 128 microgram/ml. However, this apparent in vivo activity of clindamycin against enterococci was not evident in mice given 10(9) oral enterococci; the concentrations of cecal enterococci in both clindamycin-streptomycin- and metronidazole-streptomycin-treated mice were 10(10) to 10(11) enterococci per g, with translocating enterococci recovered from approximately half of these antibiotic-treated mice. Thus antibiotic therapy with metronidazole, clindamycin, metronidazole-streptomycin, and clindamycin-streptomycin resulted in a wide variation in the cecal population levels and translocation frequencies of enterococci. This variation appeared to be related to the discrepancy between the in vivo and in vitro activities of clindamycin against enterococci.     

肠球菌属感染临床特点及耐药性研究

目的研究肠球菌属感染的临床特点及其耐药性,指导临床合理使用抗菌药物。方法采用回顾性调查方法对临床分离的924例肠球菌属相关资料进行统计分析。结果临床标本中肠球菌属在尿液中的分布最高,占71.32%;屎肠球菌与粪肠球菌对抗菌药物的耐药率不尽相同,万古霉素耐药菌株逐年增多。肠球菌属引起的院内感染病例占63.42%;60岁以上老年人占64.41%,所有患者均有较严重的基础病。结论肠球菌已是医院感染的重要致病菌,老年及免疫功能低下患者易感,以尿路感染最常见;肠球菌属对多种抗生素耐药,耐万古霉素肠球菌株明显增加。     

The activity in vitro of trospectomycin sulphate (U-63366F) against aminoglycoside-resistant enterococci

Trospectomycin (U-63366F), a 6'-propyl analogue of spectinomycin, was tested against aminoglycoside-resistant enterococci. The MIC90 for Enterococcus faecalis was 4 mg/l and that for E. faecium was 8 mg/l. Trospectomycin alone was not bactericidal for enterococci, with MBC90 4096 mg/l for both E. faecalis and E. faecium. The addition of commercially available polyvalent immunoglobulin decreased significantly both the MICs and the MBCs and the rendered trospectomycin bactericidal for enterococci. Chequerboard titration of a combination of trospectomycin with ampicillin revealed an FIC index of 1.0 for all the isolates tested. Time-kill curves also did not show any enhancement of bactericidal activity of ampicillin when combined with trospectomycin. A combination of ampicillin and gentamicin was synergistic for enterococci under similar experimental conditions. Trospectomycin can be used as a safe alternative to aminoglycosides or beta-lactam antibiotics in enterococcal infection where bactericidal activity is not required, or in the event of serious side effects from these two classes of antibiotics.     

Genetic basis for daptomycin resistance in enterococci

The emergence of multidrug-resistant enterococci as a leading cause of hospital-acquired infection is an important public health concern. Little is known about the genetic mechanisms by which enterococci adapt to strong selective pressures, including the use of antibiotics. The lipopeptide antibiotic daptomycin is approved to treat Gram-positive bacterial infections, including those caused by enterococci. Since its introduction, resistance to daptomycin by strains of Enterococcus faecalis and Enterococcus faecium has been reported but is still rare. We evolved daptomycin-resistant strains of the multidrug-resistant E. faecalis strain V583. Based on the availability of a fully closed genome sequence for V583, we used whole-genome resequencing to identify the mutations that became fixed over short time scales (~2 weeks) upon serial passage in the presence of daptomycin. By comparison of the genome sequences of the three adapted strains to that of parental V583, we identified seven candidate daptomycin resistance genes and three different mutational paths to daptomycin resistance in E. faecalis. Mutations in one of the seven candidate genes (EF0631), encoding a putative cardiolipin synthase, were found in each of the adapted E. faecalis V583 strains as well as in daptomycin-resistant E. faecalis and E. faecium clinical isolates. Alleles of EF0631 from daptomycin-resistant strains are dominant in trans and confer daptomycin resistance upon a susceptible host. These results demonstrate a mechanism of enterococcal daptomycin resistance that is genetically distinct from that occurring in staphylococci and indicate that enterococci possessing alternate EF0631 alleles are selected for during daptomycin therapy. However, our analysis of E. faecalis clinical isolates indicates that resistance pathways independent from mutant forms of EF0631 also exist.     

肠球菌感染的临床调查

目的：了解肠球菌所致感染的概况及其对抗菌药的敏感性。方法：调查与分析复旦大学附属华山医院1998年6月～1999年3月临床分离获肠球菌住院患的临床资料,用KB法测定细菌药敏。结果：116例患中,属医院感染、院外感染分别为37和13例,带菌66例,感染部位多为尿路(64％)、次为腹腔(18％),粪肠球菌(64％)多于屎肠球菌(36％)。患严重基础疾病、接受介入诊疗操作、应用广谱抗菌药可能是肠球菌医院感染的危险因素。药敏结果显示：氨苄西林、万古毒素对肠球菌抗菌活性相对较高,抑菌率分别为75．8％和96．9％,屎肠球菌耐药率高于粪肠球菌。结论：肠球菌已成为医院感染患主要病原菌之一,及时、合理诊治是治愈该类感染的关键。     

Effects of various enteral nutrition solutions on bacterial translocation and intestinal morphology during the postoperative period

Bacterial translocation is the passage of bacteria or endotoxins from the gastrointestinal tract to extraintestinal sites, such as mesenteric lymph nodes, liver, spleen, and bloodstream. In this study, the investigators examined the effects of various enteral nutrients on bacterial translocation and intestinal morphology during the postoperative period. Sixty rats were randomly divided into 5 groups, each of which included 12 animals; cecal mobilization was performed in all groups. Group I rats were fed rat chow and water; group II was given standard enteral nutrients; group III, high-energy enteral nutrients; group IV, enteral nutrients supplemented with fiber; and group V, immunonutrients. Bacterial translocation was detected in mesenteric lymph nodes, spleen, liver, and blood cultures. Changes in the terminal ileum were scored from 0 to 4 with the morphologic scoring system. Bacterial translocation was predominantly detected in mesenteric lymph nodes. Rats fed immunonutrients (group V) showed a significant reduction in bacterial translocation compared with other groups. Although minor morphologic alterations in the villi were observed in groups IV and V, the histologic scores of these groups were not statistically different from the scores of control group members. In the present study, investigators evaluated the effects of various enteral nutritional solutions on bacterial translocation and intestinal morphology during the postoperative period. Enteral diets supplemented with arginine, nucleotides, and ω-3 fatty acids were found to reduce bacterial translocation. The investigators concluded that this effect might be related to improvement in immune function resulting from the use of immunonutrients.     

Presence of vancomycin-resistant enterococci in farm and pet animals.

Enterococcus faecium strains with vanA-mediated glycopeptide resistance were isolated by enrichment culture from the intestines and feces of several animal species, mainly horses and dogs (8% positive), chickens (7% positive), and pigs (6% positive). Other vanA-positive enterococcal strains were identified as E. durans in gallinaceous birds, E. faecalis in a horse, and E. gallinarum in a pheasant. Samples from pigeons, cage birds, and ruminants were negative. It was concluded that vancomycin resistance is widespread among isolates from farm and pet animals.     

肠球菌医院感染分布及耐药监测

目的 了解肠球菌院内感染分布及耐药特性。方法 英国SENSITIRE(先德)荧光快速微生物鉴定／药敏分析仪进行细菌鉴定及药敏试验,用纸片扩散法进行庆大霉素高水平耐药筛选试验。结果 肠球菌感染以泌尿道感染为主,占50.5％。肠球菌表现多重耐药,不同菌种对氨苄西林、利福平耐药率有明显差异,对常用抗生素的耐药率,屎肠球菌明显高于粪肠球菌,HLGR株明显高于低耐株。结论 肠球菌对抗茵药物耐药谱有明显差异,合理选择抗生素,对控制院内感染有重大意义。     

宁波地区医院肠球菌的临床分布及耐药研究

目的了解医院肠球菌在临床分布状况及利奈唑胺等抗菌药物对肠球菌的抗菌活性,为临床治疗肠球菌感染合理选择抗菌药物提供指导。方法对本院各种标本分离获得的肠球菌用VITEK微生物自动鉴定仪进行种的鉴定和药物敏感性试验。用WHOVET5软件对统计结果进行分析。结果三年共检出706株肠球菌,其中粪肠球菌432株占肠球菌61．2％,屎肠球菌241株占34．1％,鹑鸡肠球菌33株占4．7％。粪肠球菌对呋喃妥因、青霉素、四环素、莫西沙星、左氧氟沙星的耐药率分别为5．8％、22．2％、71．0％、16．7％和23．8％,而屎肠球菌的耐药率除四环素外均高于粪肠球菌。本组试验发现3株耐万古霉素肠球菌,耐药率为0．43％,肠球菌对利奈唑胺的敏感率为100％。结论肠球菌属细菌在医院内感染逐年增加,耐药率在不断上升,泛耐株在不断增多,本组试验检出3株耐万古霉素肠球菌（VRE）。未发现耐利奈唑胺肠球菌,利奈唑胺是目前治疗泛耐株肠球菌特别是治疗耐万古霉素肠球菌感染的最佳选择,但必须合理使用,同时要密切监测肠球菌的耐药趋势,防止耐药菌株的产生。     

Prospective evaluation of virulence factors of enterococci isolated from patients with peritonitis: impact on outcome

The objective of this study was to evaluate the prevalence of 4 virulence factors (VFs) of enterococci (cytolysin [cyl], gelatinase [gel], aggregation substance [agg], and enterococcal surface protein [esp]) and their relationship to outcome in patients with generalized peritonitis in a prospective cohort study. VF expression in each strain was assessed by polymerase chain reaction assay with specific primers. Outcome of the patients was recorded. Ninety-nine strains of Enterococcus were obtained from the peritoneal fluid of 81 patients. Fifty-eight patients had at least 1 strain bearing [cyl] (13.1% of the strains), [gel] (50.5% of the strains), [agg] (40.4% of the strains), and [esp] (34.3% of the strains). The presence of VF of Enterococcus was independently associated with mortality: odds ratio, 5.5; 95% confidence interval, 1.3-28.1. In conclusion, VF accounted for 72% of the patients with enterococci isolated from the peritoneal fluid and was independently associated with mortality in severe peritonitis.     

258株肠球菌耐药性分析及耐万古霉素基因检测

目的研究肠球菌的耐药率及耐万古霉素肠球菌(VRE)的耐药表型和基因型。方法按照美国临床和实验室标准化研究所(CLSI)2009年推荐的微量稀释法进行临床分离肠球菌对各类药物的最小抑菌浓度(MIC)检测,VRE进一步用E-test药敏试验确认;PCR法检测VRE的耐药基因。结果 2010年7月至2011年11月沈阳军区总医院共检出粪肠球菌95株,屎肠球菌163株。粪肠球菌对万古霉素、替考拉宁保持较高敏感度,对氨苄西林、青霉素、呋喃妥因三种抗菌药物敏感度也在65%以上,对其他抗菌药物敏感度低,统计期内未检出耐万古霉素粪肠球菌菌株。屎肠球菌对多数抗菌药物表现为耐药,对氯霉素敏感率为70%,对万古霉素、替考拉宁敏感度下降,为90.7%。期间检出15株VRE,其耐药表型为多重耐药,PCR扩增结果显示,15株万古霉素耐药屎肠球菌VanA基因扩增均为阳性,产物长度在700～1000bp之间,约783bp,符合预期;VanB、VanC引物扩增均阴性。15株万古霉素耐药屎肠球菌对多数抗菌药物耐药,仅对氯霉素、四环素相对敏感,对万古霉素MIC>256mg/L,对替考拉宁也表现为耐药。结论屎肠球菌耐药性高于粪肠球菌,VRE多为多重耐药,给临床治疗带来困难,医院应加强对其预防监测。     

Evaluation of phenotypic characteristics for differentiation of enterococcal species using an example based algorithm

A computer based rule-generation system of Inductive Learning by Logic Minimization (ILLM) was used to determine the sufficient set of biochemical reactions and necessary conditions that have to be fulfilled for correct differentiation of enterococci recovered from humans. The simplest combination of physiological tests for differentiation Enterococcus faecalis from all other enterococcal species consisted of only 3 reactions. Reactions that tested the ability of acidification D-xylose, mannitol, L-arabinose and Na-pyruvate were useful for delineation of both E. faecalis and E. faecium from all other enterococci. For differentiation of all 12 currently known clinically significant species of enterococci any one of 3 sets of nine tests suggested by ILLM could be used. The tests suggested by ILLM were applied to 153 isolates of enteroccoci recovered at our Department of Microbiology and all E. faecalis (138, 90.2%), E. faecium (13, 8.5%) and E. avium strains (2, 1.3%) were correctly differentiated.     

Antimicrobial Susceptibility Patterns of Enterococci Causing Infections in Europe

In vitro susceptibilities of 4,208 enterococci (83% Enterococcus faecalis isolates, 13.6% Enterococcus faecium isolates, and 3.4% isolates of other species) from patients in 27 European countries towards 16 antibiotics were determined. High-level resistance to gentamicin varied by country (range, 1 to 49%; mean, 22.6% +/- 12. 3%) and per species (19.7% E. faecalis isolates, 13.6% E. faecium isolates, 3.4% by other species). Vancomycin resistance was detected in 0.06% E. faecalis, 3.8% E. faecium, and 19.1% isolates of other species. All enterococci were susceptible to LY 333328 and everninomicin, and 25% of E. faecalis isolates and 85% of other enterococci were susceptible to quinupristin-dalfopristin. The MIC of moxifloxacin and trovafloxacin for ciprofloxacin-susceptible E. faecalis at which 90% of the isolates were inhibited was 0.25 to 0.5 microg/ml.     

424株临床分离肠球菌属细菌的耐药性变异

目的探讨肠球菌属临床分离情况与耐药变迁,为指导临床合理用药,控制感染提供依据。方法对广东省东莞中山大学附属东华医院2007--2009年临床送检标本进行常规微生物培养、鉴定和药敏试验,并用WHONET5．4软件统计分析这3年间肠球菌临床分离株在各标本、科室中的分布与耐药性的变迁情况。结果2007--2009年临床分离出肠球菌属细菌424株,其中粪肠球菌338株,占79．7％,屎肠球菌75株,占17．7%,鸟肠球菌11株,占2．6％;肠球菌属在各标本中的分布以尿液为主,占50．2％,其次为伤口分泌物（14．4％）、血液（12．5％）。3年来肠球菌属的菌种和耐药均发生了较大变化,粪肠球菌所占比率每年保持在80％左右,屎肠球菌呈逐年上升趋势,从2007年的13．9%上升至2009年的20．9％,而鸟肠球菌则逐年下降,从4．7％降至0．6％。粪肠球菌对红霉素和四环素的耐药率最高,分别为79．4％～85．7％和84．1％～87．4%,屎肠球菌对氨苄西林、青霉素以及呋喃妥因的耐药率明显高于粪肠球菌,对红霉素、左氧氟沙星、青霉素的耐药率高达80％以上,对呋喃妥因、高浓度的庆大霉素、环丙沙星、四环素、氨苄西林等抗菌药物的耐药率也接近或超过50％。2007年发现1株屎肠球菌对万古霉素耐药。结论肠球菌属耐药性较为严重,不同菌种耐药性有所差异。临床抗感染治疗应以分离菌株的体外抗菌药物敏感性为依据,合理选用抗菌药物,以提高疗效。     

In vitro susceptibilities of enterococcal blood culture isolates from the Hamburg area to ten antibiotics

Treatment of enterococcal infections is often difficult because of intrinsic and acquired resistance to a variety of antimicrobial agents. Between January 1993 and May 1997, enterococci were isolated from blood cultures of 117 patients at the Institute of Medical Microbiology and Immunology, University Hospital Eppendorf, Hamburg, Germany. Eightynine (76%) isolates were phenotypically identified as Enterococcus faecalis, and 24 (21%) as Enterococcus faecium. All E. faecalis isolates, but only 17% of the E. faecium isolates were susceptible to ampicillin. Two E. faecium isolates (8%) but no E. faecalis were vancomycin resistant (vanA genotype). Quinupristin/dalfopristin shows a high degree of susceptiblity of E. faecium (79%) and may be suitable for the therapy of infections caused by glycopeptide-resistant E. faecium strains.     

Emergence and management of drug-resistant enterococcal infections

The treatment of multidrug-resistant enterococcal infections continues to be a challenge for clinicians. Glycopeptide and beta-lactam resistance is now a common feature of the majority of Enterococcus faecium hospital isolates, and resistance to aminoglycosides, quinupristin-dalfopristin, linezolid and daptomycin further complicates the problem. New antibiotics, such as tigecycline, lipoglycopeptides (dalbavancin, oritavancin and telavancin) and cephalosporins with activity against Enterococcus faecalis (ceftobiprole and ceftaroline), may have potential activity against certain resistant enterococcal strains in specific clinical settings, as may some older antibiotics, such as ampicillin, chloramphenicol, doxycycline, minocycline and nitrofurantoin. However, the treatment of endovascular infections (particularly endocarditis, where bactericidal therapy is important for optimal cure rates) caused by resistant enterococci continues to be an immense challenge even with the availability of new agents. The optimal therapy for these infections is not well established and clinical data are usually limited to case reports with conflicting results. Therefore, treatment decisions may have to be based on animal models and sporadic experiences and the best approach is for the physician to consider carefully each patient on a case by case manner and gather all the clinical and microbiological information possible regarding species identification and susceptibilities in order to choose a therapeutic regimen that would appear to be active.     

Antimicrobial susceptibility patterns of enterococci in intensive care units in Sweden evaluated by different MIC breakpoint systems.

Three hundred and twenty-two (322) clinical isolates were collected from patients admitted to intensive care units (ICUs) at eight Swedish hospitals between December 1996 and December 1998. Of the isolates, 244 (76%) were Enterococcus faecalis, 74 (23%) were Enterococcus faecium and four (1%) were other Enterococcus spp. MICs of ampicillin, imipenem, meropenem, piperacillin/tazobactam, ciprofloxacin, trovafloxacin, clinafloxacin, gentamicin, streptomycin, vancomycin, teicoplanin, quinupristin/dalfopristin, linezolid and evernimicin were determined by Etest. Susceptible and resistant isolates were defined according to the species-related MIC breakpoints of the British Society for Antimicrobial Chemotherapy (BSAC), the National Committee for Clinical Laboratory Standards (NCCLS) and the Swedish Reference Group for Antibiotics (SRGA). Tentative breakpoints were applied for new/experimental antibiotics. Multidrug resistance among enterococci in ICUs is not uncommon in Sweden, particularly among E. faecium, and includes ampicillin resistance and concomitant resistance to fluoroquinolones. Almost 20% of E. faecalis isolates showed high-level resistance to gentamicin and concomitant resistance to fluoroquinolones. Vancomycin-resistant enterococci were only found sporadically. Among the new antimicrobial agents, linezolid and evernimicin showed the best activity against all enterococcal isolates. There was good concordance between the BSAC, NCCLS and SRGA breakpoints in detecting resistance. When applying the SRGA breakpoints for susceptibility, isolates were more frequently interpreted as intermediate. This might indicate earlier detection of emerging resistance using the SRGA breakpoint when the native population is considered susceptible, but with the risk that isolates belonging to the native susceptible population will be incorrectly interpreted as intermediate.     

肠球菌耐药现状调查及抗感染用药探讨

目的了解肠球菌尤其是对万古霉素耐药肠球菌（ＶＲＥ）和庆大霉素高水平耐药（ＨＬＧＲ）肠球菌的耐药状况,指导临床合理用药。方法对北京５家教学医院感染标本中分离出的１６１４株肠球菌,分别进行纸片扩散法药敏试验和β内酰胺酶测试,并以“ＷＨＯＮＥＴ４”软件对试验数据进行分析处理。结果ＶＲＥ和ＨＬＧＲ肠球菌分别占肠球菌感染标本总数的３．４％和５２．６％,产β内酰胺酶的肠球菌占５．８％;对常用抗生素的耐药率,屎肠球菌明显高于粪肠球菌,ＨＬＧＲ株明显高于低耐株;万古霉素和高浓度庆大霉素多重耐药株检出率为０．９％。结论肠球菌对临床常用的８种抗生素以万古霉素最敏感。对不同特征肠球菌感染应采取不同的治疗方案。