葡萄球菌中红霉素对克林霉素诱导型耐药的检测及耐药性分析

目的:了解诱导型克林霉素耐药的葡萄球菌的耐药状况及发生率.方法:用常规方法对2007年1月～2009年12月各种临床标本进行培养,MicWalK 40微生物鉴定仪进行鉴定及药物的敏感性试验检测,红霉素诱导克林霉素耐药试验采用双纸片法进行.结果:350株葡萄球菌中结构型克林霉素耐药葡萄球菌有112株,占32.0%,诱导型克林霉素耐药的葡萄球菌有36株,占10.3%,36株诱导型克林霉素耐药的葡萄球菌对利奈唑胺、万古霉素、奎奴普汀/达福普宁均100.0%敏感.结论:葡萄球菌对克林霉素的耐药主要是结构型耐药,利奈唑胺、万古霉素、奎奴普汀/达福普宁对克林霉素诱导型葡萄球菌有良好体外抗菌活性.     

In vitro activity of RBx 7644 (ranbezolid) on biofilm producing bacteria

Biofilm associated infections are becoming more common. Treatment outcome of device related infections cannot be predicted by the results of a standard susceptibility test such as the MIC. Microorganisms involved in device related infections have a slow growth rate and adhere to surfaces. Activity against glass adherent bacteria has been shown to be correlated with treatment outcome in animal models of catheter related infections. Drug efficacy can be predicted if glass adherent staphylococci are killed by low drug concentration. The eradication of bacteria adhering to glass beads and inhibition of biofilm formation by ranbezolid and three other antibiotics (quinupristin/dalfopristin, vancomycin and linezolid) was studied. The results indicated that ranbezolid required only (2-4 x MIC) for total clearance of glass-adherent MRSA 562 and MRSE 879, compared with vancomycin (8 x), quinupristin/dalfopristin (1-4 x) and linezolid (4-16 x MIC). In addition ranbezolid inhibited biofilm formation to a greater extent at sub MIC and MIC level. In conclusion, this study indicated that ranbezolid had potent activity against adherent staphylococci isolates and may prove useful in the prevention and treatment of device related infections caused by staphylococci.     

Assessment of pathogen occurrences and resistance profiles among infected patients in the intensive care unit: report from the SENTRY Antimicrobial Surveillance Program (North America, 2001)

Originating from 25 selected intensive care units (ICUs) in North America, a total of 1,321 bacterial strains from blood, respiratory tract, urine and wound sites were processed at a central laboratory as part of the SENTRY Antimicrobial Surveillance Program (2001) to assess their occurrence rates and antimicrobial susceptibility profiles. The rank order of pathogens recovered was Staphylococcus aureus (24.1%), Pseudomonas aeruginosa (12.2%), Escherichia coli (10.1%), Klebsiella spp. (8.9%), Enterococcus spp. (7.2%), coagulase-negative staphylococci (7.0%) and Enterobacter spp. (7.0%). Although oxacillin resistance among S. aureus was 51.4%, no resistance was detected to vancomycin, linezolid and quinupristin/dalfopristin. The most active agents tested against P. aeruginosa were amikacin, cefepime, tobramycin, meropenem and piperacillin/tazobactam (3.1-13.0% resistance). Among agents tested against the Enterobacteriaceae, amikacin, cefepime, imipenem and meropenem showed greatest in vitro activity (0.0-3.4% resistance). Extended-spectrum beta-lactamase-producing phenotype rates were 11.2 and 16.2% in E. coli and Klebsiella spp., respectively. Linezolid was most active against enterococci (1.1% resistance; G2576U ribosomal mutation) whereas 28.4% of isolates were resistant to vancomycin. Cefepime and the carbapenems (imipenem or meropenem) for Gram-negative isolates and linezolid for Gram-positive isolates, provided the broadest spectrum of in vitro activity against contemporary ICU pathogens in North America.     

Comparative in vitro activity of antiribosomal agents on penicillin-susceptible and -resistant Streptococcus pneumoniae in relation to their resistance genotypes

A collection of 326 strains of Streptococcus pneumoniae isolated from blood, cerebrospinal fluid, bronchoalveolar lavage, transtracheal aspirate or sputum from January 1996-June 2002 were included in this study. The activity of clarithromycin, clindamycin, telithromycin, linezolid and quinupristin/dalfopristin against penicillin G and erythromycin A susceptible and resistant pneumococci were determined; the erythromycin A resistance phenotypes and genotypes were identified and susceptibilities of these agents were assessed according to the resistance genotypes. MICs were determined for all strains of pneumococci using an agar dilution method. MLS(B) resistance phenotypes were determined by the double disk (erythromycin A and clindamycin) diffusion method. Genetic determinants for macrolide resistance were identified by PCR using primers specific for erm(B) and mef(A). Erythromycin A resistance was detected in 13.8% of the strains. MLS(B) resistance phenotype was observed in 82% of these (60% being cMLS(B) and 40% being iMLS(B)), and M type resistance in about 18%. All the MLS(B) phenotype strains except four, revealed the presence of erm(B) gene and all except one M phenotype strains revealed the mef(A) gene. Of the erythromycin A resistant pneumococci about 49% were also resistant to clindamycin. No strains were resistant to telithromycin, quinupristin/dalfopristin and linezolid. Telithromycin had the lowest MIC values for both erythromycin A resistant and susceptible strains of all the antiribosomal agents tested. The most prevalent mechanism of macrolide resistance was mediated by the erm(B) gene leading to the expression of MLS(B) phenotype. Telithromycin was the most active antiribosomal agent, regardless of the macrolide resistance genotype of the pneumococci tested.     

Macrolide resistance phenotypes of commensal viridans group streptococci and Gemella spp. and PCR detection of resistance genes

One hundred and sixty viridans group streptococci (VGS) and 26 Gemella spp. resistant to erythromycin were studied to detect macrolide lincosamide and streptogramin B (MLS_B) phenotypes and to investigate resistance rates to other antibiotics. The M phenotype was most prevalent in both bacterial groups (59.6% in VGS, 69.2% in gemellae) and the iMLS_B phenotype was found least often (9.3 and 13.9%, respectively). All isolates with M phenotype had the mef(A/E) gene, being prevalent the mef(E) subclass. cMLS_B and iMLS_B strains contained the erm(B) gene, alone or in combination with the mef(A/E) gene. Thirteen isolates were intermediately resistant to quinupristin/dalfopristin and 11 strains showed low susceptibility to telithromycin. Linezolid was active against all the isolates tested and tetracycline resistance was the major one in VGS (41.6%) and Gemella spp. (46.2%).     

表皮葡萄球菌的耐药性分析

目的 分析临床分离的表皮葡萄球菌的耐药性,为临床治疗此类病菌所致眼内炎提供用药依据.方法 收集2010年1-12月我院从39例眼内炎患者玻璃体液中分离出的39株表皮葡萄球菌,并采用最小抑菌浓度法进行药物敏感试验.采用WHONET5.4软件进行数据统计和分析.结果 39株表皮葡萄球菌对多数抗菌药物耐药严重,其中对青霉素G的耐药率最高,达100.0%,但未发现对万古霉素、利奈唑胺、喹努普汀/达福普汀、替考拉宁耐药的菌株.结论 临床医生必须结合抗生素药物敏感试验结果合理使用抗生素,尽可能避免耐药菌株的产生.

Abstract：

Objective To approach drug-resistance status of clinically isolated staphyloccus epidermidis and to provide the evidence for clinically reasonable use of antibiotics. Methods A total of 39 strains of staphyloccus epidermidis were isolated from 39 endophthalmitis patients from January to December in 2010. The drug sensitivity testing was performed by minimum inhibitory concentration methods. Statistical analysis was done by Whonet-S. 4 software. Results Among the 39 strains, the staphyloccus epidermidis were resistant to the commonly used antibiotics in different degrees, among which the resistancee rate of penicillin G( 100% ) was the highest. The resistance of vancomycin, teicoplanin, linezolid and quinupristin/dalfopristin were 0. 0%. Conclusion Clinicians should use antibiotics based on antibiotic drugs sensitive results to avoid drug-resistant strains.     

2010-2012年院内金黄色葡萄球菌的耐药情况分析

目的 对本院3年来金黄色葡萄球菌的耐药情况进行分析,并且对耐甲氧西林金黄色葡萄球菌（MRSA）与甲氧西林敏感金黄色葡萄球菌（MSSA）的耐药性差异做对比,为临床合理使用抗生素提供依据.方法 对临床分离的442株金黄色葡萄球菌,采用PHOENIX100全自动微生物分析仪和WHONET软件,按照美国实验与临床标准协会（C LSI）的标准对金黄色葡萄球菌的耐药情况进行回顾性分析.结果 3年内共分离金黄色葡萄球菌442株,其中耐甲氧西林金黄色葡萄球菌（MRSA）281株.分离出金黄色葡萄球菌的标本中以痰标本为主,占68.0％,其次为分泌物和血液.除万古霉素、利奈唑胺、奎奴普丁/达福普丁外,耐甲氧西林金黄色葡萄球菌（MRSA）对其余抗菌药物的耐药率均高于甲氧西林敏感金黄色葡萄球菌（MSSA）,差异有统计学意义（P＜0.05）.除万古霉素、利奈唑胺、奎奴普丁/达福普丁保持较低的耐药率外,其余常规抗生素的耐药率均保持在30％以上.结论 耐甲氧西林金黄色葡萄球菌（MRSA）对大部分抗菌药物仍维持较高的耐药率,应定期监测临床标本中分离的金黄色葡萄球菌耐药率,合理使用抗菌药物,延缓金黄色葡萄球菌临床株耐药性的增长,控制医院感染的发生及暴发.     

Antibiotic resistance rates and macrolide resistance phenotypes of viridans group streptococci from the oropharynx of healthy Greek children

A total of 200 isolates of viridans group streptococci isolated from the oropharynx of healthy Greek children were studied. Vancomycin, rifampicin, fluoroquinolones and dalfopristin/quinupristin were active against all tested isolates. High level resistance to gentamicin was not seen. Intermediate and high-level penicillin resistance was present in 28.5 and 14.5% isolates, respectively, with 41.3% of the latter group, being also resistant to cefotaxime. Resistance rates to other antimicrobials were as follows - erythromycin 38.5%, clarithromycin 33.5%, clindamycin 7.5% and tetracycline 23%. Penicillin resistance occurred more frequently in Streptococcus mitis isolates, while macrolide resistance was more frequent in S. oralis. MLSB resistance phenotype M was dominant (74%) among erythromycin resistant isolates, with phenotypes IR and CR being represented by 6 and 20% of isolates, respectively.     

Distribution of tetracycline resistance genes tet(M), tet(O), tet(L) and tet(K) in blood isolates of viridans group streptococci harbouring erm(B) and mef(A) genes. Susceptibility to quinupristin/dalfopristin and linezolid

Susceptibility to erythromycin, tetracycline, clindamycin, quinupristin/dalfopristin and linezolid was investigated using 111 consecutive non-duplicate blood culture isolates of viridans-group streptococci (VGS). The erm(B) and mef(A) genes were detected, either alone or in combination, in the 47 (42%) erythromycin-resistant strains. The tet(M) gene alone was predominant (78%) in the 36 (35%) tetracycline-resistant isolates. Two isolates carried the tet(O) gene alone and two others the tet(L) associated with tet(O) or tet(M). The association between erythromycin and tetracycline resistance was common and the erm(B) and tet(M) determinants seem to be associated in our VGS. We found three isolates resistant to quinupristin/dalfopristin, all of them were erythromycin and tetracycline-resistant. For all isolates tested, linezolid MICs were ≤2 mg/l.     

In vitro activity of daptomycin against clinical isolates with reduced susceptibilities to linezolid and quinupristin/dalfopristin

An initiative was taken to determine the in vitro activity of daptomycin against 85 Gram-positive isolates with reduced susceptibilities to linezolid and quinupristin/dalfopristin. Daptomycin had potent activity against all strains, with a Staphylococcus spp. minimum inhibitory concentration (MIC) < or =2 microg/mL and an Enterococcus spp. MIC < or =8 microg/mL. Resistance to linezolid and quinupristin/dalfopristin appears to be independent of reduced susceptibility to daptomycin.     

Linezolid and quinupristin/dalfopristin resistance in vancomycin-resistant enterococci and methicillin-resistant Staphylococcus aureus prior to clinical use in Turkey

The aim of this study was to determine the in vitro antimicrobial activity of recently licensed quinupristin/dalfopristin and linezolid which have not yet been in clinical use in Turkey against methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE) strains isolated from various clinical specimens by using the Etest. The results showed that all MRSA strains were fully susceptible to both the new compounds. All strains were inhibited by 1 mg/l quinupristin/dalfopristin (mode MIC 0.38 mg/l) and by 3 mg/l linezolid (mode MIC 1.5 mg/l). Four strains of Enterococcus faecium showed an increase of resistance of 2-3 mg/l to quinupristin/dalfopristin (susceptible mode MIC 0.38 mg/l). With linezolid, all strains except two fell within the range 0.75-2.0 mg/l.     

粪肠球菌和屎肠球菌的耐药性分析

目的了解粪肠球菌和屎肠球菌对抗感染药物的耐药性,为临床提供治疗依据。方法对住院及门诊患者送检样本中培养分离出281株肠球菌（粪肠球菌112株,屎肠球菌169株）的感染分布与耐药情况进行分析。采用稀释法进行药物敏感试验,结果按美国临床实验室标准化研究所标准判定。结果屎肠球菌对青霉素G的耐药率最高（93．7％）,其次为红霉素、氨苄西林和环丙沙星。粪肠球菌对奎奴普丁／达福普汀耐药率最高为（74．0％）,其次为高浓度庆大霉素、四环素、红霉素和环丙沙星。粪肠球菌和屎肠球菌对利奈唑胺和万古霉素的耐药率均低于2．0％,替考拉宁的耐药率最低（均为0）。结论粪肠球菌和屎肠球菌对不同抗感染药物的耐药率有较大差异,在抗感染治疗前应先做细菌培养和药物敏感试验,依据报告结果合理选用抗感染药物。     

我院2004-2011年金黄色葡萄球菌对甲氧西林耐药性的动态变化特征分析

目的：了解我院金黄色葡萄球菌（SAU）的临床分布及耐甲氧西林金黄色葡萄球菌（MRSA）的耐药特征。方法：采用药敏纸片法和WHONET5.0软件对我院2004-2011年从临床分离的1608株SAU的分布及耐药情况进行回顾性分析。结果：SAU的主要来源为痰（占61.2%）,其次为伤口分泌物（占11.8%）、脓液（占8.1%）和血液（占7.9%）;SAU感染发生率较高的科室是重症监护室（占18.2%）、呼吸科（占17.4%）和神经科（占17.1%）;MRSA对氨基糖苷类、大环内酯类、林可酰胺类、氟喹诺酮类的耐药率与甲氧西林敏感金黄色葡萄球菌（MSSA）对上述药的耐药率比较,差异有极显著统计学意义（P〈0.01）。结论：我院MRSA对常用抗菌药物耐药性较强,多重耐药现象严重,对MRSA仍保持较强抗菌活性且耐药率小于30%的抗菌药物有利奈唑胺、替考拉宁、万古霉素、奎奴普丁/达福普汀、复方磺胺甲唑和呋喃妥因。合理使用抗菌药物、加强感染控制及寻找新的治疗手段对减缓耐药细菌的增长十分重要。     

儿科金黄色葡萄球菌感染的耐药性分析

目的对笔者所在医院儿科分离的金黄色葡萄球菌进行耐药性分析,为临床合理使用抗菌药物提供依据。方法回顾性分析笔者所在医院儿科分离的233株SAU标本来源及临床科室分布情况,并进行耐药性分析;采用VITEK-2COMPART仪器进行药敏试验,苯唑西林筛选出耐甲氧西林金黄色葡萄球菌。结果 233株SAU在痰标本及儿科重症监护室检出比例最大,分别为68.67%和31.33%;共检出MRSA40株,其检出率17.17%;在SAU中利奈唑烷、利福平、莫西沙星、喹奴普汀/达福普汀和万古霉素耐药率均为0;MRSA对红霉素、氯洁霉素、四环素、环丙沙星的耐药率显著高于甲氧西林敏感金黄色葡萄球菌,差异有统计学意义(P<0.05)。结论临床在确诊SAU感染时,应区别对待MSSA和MRSA,及时、合理使用抗生素预防和控制感染。     

儿童感染肺炎链球菌的分布及耐药性分析

目的：分析儿童肺炎链球菌（SP）对常用抗生素的耐药情况。方法采用法国梅里埃公司的VITEK 2 Compact全自动细菌鉴定仪对本院2013年儿童感染SP分离情况及抗菌药物敏感性进行回顾性的分析。结果痰液、咽拭子为SP主要标本来源,分别占96.4%和2.9%;在280株SP中对常用抗菌药物的耐药率有普遍上升趋势,其中对红霉素、四环素、复方新诺明的耐药率较高（〉80%）,对青霉素类和三代头孢类的耐药率较低（〈40%）,对氯霉素、泰利霉素和美罗培南的耐药率更低（〈10%）,对利奈唑胺、万古霉素、厄它培南和氟喹诺酮类均无耐药性。结论加强对SP的耐药性检测,以指导临床医生制定合理有效的治疗及用药方案。     

Activities of clindamycin,synercid, telithromycin,linezolid, and mupirocin against gram-positive coccal strains resistant to erythromycin in korea

The antibacterial activities of clindamycin, synercid, telithromycin, linezolid and mupirocin were evaluated against erythromycin-resistant Gram-positive coccal clinical isolates collected in Korean hospitals. In Staphylococcus aureus, synercid, linezolid and mupirocin were the most active agents. Against coagulase-negative staphylococci (CNS), synercid, linezolid and mupirocin were also active. Telithromycin and synercid resistance was common against enterococci, only linezolid and mupirocin were active. The reason of low activity of telithromycin against staphylococci and enterococci is because most of the isolates were constitutively resistant to erythromycin. Synercid, telithromycin, linezolid and mupirocin were active against streptococci.     

耐甲氧西林金黄色葡萄球菌耐药表型分型与耐药基因检测分析研究

目的分析研究耐甲氧西林金黄色葡萄球菌(methicillin-resistant staphylococcus aureus,MRSA)的耐药表型及耐药基因,探索治疗MRSA感染的有效手段。方法对临床分离的耐甲氧西林金黄色葡萄球菌株,依据美国临床实验室标准化研究所(CLSI)标准操作规程进行万古霉素、利奈唑胺和苯唑西林等药物的药物敏感性试验和耐药基因检测,分别采用微量肉汤稀释法和多重聚合酶链反应(PCR)扩增法。结果 MRSA耐药表型分为Ⅰ~Ⅶ型,MRSA对抗生素产生多重耐药,万古霉素、利奈唑胺、氯霉素、复方新诺明、利福平耐药率分别为0、7.0%、40.8%、47.9%、60.6%,β-内酰胺类药物耐药率高达100%;实验菌株mecA、ermA、ermC、tetK、tetM、ratA基因检出率分别为98.6%、60.6%、18.3%、100%、7.0%和0。结论 MRSA对万古霉素、利奈唑胺敏感,其他药物呈多重耐药,需加强MRSA对万古霉素、利奈唑胺、氯霉素、复方磺胺、利福平等常用药物最小抑菌浓度(MIC)监测和临床报告,关注万古霉素对MRSA治疗不佳患者。     

Bactericidal activity of quinupristin-dalfopristin against strains of Staphylococcus aureus with the MLS(B) phenotype of resistance according to the erm gene type

The bactericidal activity of quinupristin-dalfopristin was assessed by time-kill experiments against Staphylococcus aureus strains with characterized phenotypes and genotypes of MLS(B) resistance. A set of laboratory strains composed of isogenic pairs of S. aureus RN4220 derivatives containing or not the erm(A), erm(B) or erm(C) genes constitutively expressed and of 13 clinical isolates containing these genes inducibly or constitutively expressed were studied. Three of the clinical isolates with erm(B) or erm(A) genes had an unusual inducible MLS(B) cross resistance. The early bactericidal activity of quinupristin-dalfopristin was altered against strains expressing constitutive quinupristin resistance regardless of the erm(A), erm(B) or erm(C) type of gene. We conclude that the bactericidal activity of quinupristin-dalfopristin against staphylococci was dependent on the activity of quinupristin rather than on the erm genotype of the strain.     

Antimicrobial resistance and the mechanisms implicated in faecal enterococci from healthy humans, poultry and pets in Portugal

Antimicrobial resistance and the mechanisms implicated were studied in 440 enterococci (227 Enterococcus faecium, 177 Enterococcus faecalis, 32 Enterococcus hirae and 4 Enterococcus durans) recovered from 220 faecal samples of healthy humans, poultry and pets in Portugal. Higher levels of resistance were detected for ampicillin, tetracycline, erythromycin and chloramphenicol in poultry isolates (10.5%, 97%, 87.5% and 16%, respectively) compared with human isolates (0%, 26%, 31.5% and 5%, respectively); intermediate levels of resistance for these antibiotics were found in pet isolates. Thirty-three per cent of the E. faecium isolates of poultry origin showed quinupristin/dalfopristin resistance. High-level resistance to gentamicin or streptomycin was detected in 1-7% of isolates in our series of enterococci. The aac(6')-aph(2'), aph(3')-IIIa, erm(B) and tet(M) genes were demonstrated in most of the gentamicin-, kanamycin-, erythromycin- and tetracycline-resistant isolates, respectively. The vat(E) gene was found in 39% of the quinupristin/dalfopristin-resistant E. faecium isolates of poultry origin.     

Treatment options for vancomycin-resistant enterococcal infections

Serious infection with vancomycin-resistant enterococci (VRE) usually occurs in patients with significantly compromised host defences and serious co-morbidities, and this magnifies the importance of effective antimicrobial treatment. Assessments of antibacterial efficacy against VRE have been hampered by the lack of a comparator treatment arm(s), complex treatment requirements including surgery, and advanced illness-severity associated with a high crude mortality. Treatment options include available agents which don't have a specific VRE approval (chloramphenicol, doxycycline, high-dose ampicillin or ampicillin/sulbactam), and nitrofurantoin (for lower urinary tract infection). The role of antimicrobial combinations that have shown in vitro or animal-model in vivo efficacy has yet to be established. Two novel antimicrobial agents (quinupristin/ dalfopristin and linezolid) have emerged as approved therapeutic options for vancomycin-resistant Enterococcus faecium on the basis of in vitro susceptibility and clinical efficacy from multicentre, pharmaceutical company-sponsored clinical trials. Quinupristin/dalfopristin is a streptogramin, which impairs bacterial protein synthesis at both early peptide chain elongation and late peptide chain extrusion steps. It has bacteriostatic activity against vancomycin-resistant E. faecium [minimum concentration to inhibit growth of 90% of isolates (MIC(90)) = 2 microg/ml] but is not active against Enterococcus faecalis (MIC(90 )= 16 microg/ml). In a noncomparative, nonblind, emergency-use programme in patients who were infected with Gram-positive isolates resistant or refractory to conventional therapy or who were intolerant of conventional therapy, quinupristin/dalfopristin was administered at 7.5 mg/kg every 8 hours. The clinical response rate in the bacteriologically evaluable subset was 70.5%, and a 65.8% overall response (favourable clinical and bacteriological outcome) was observed. Resistance to quinupristin/dalfopristin on therapy was observed in 6/338 (1.8%) of VRE strains. Myalgia/arthralgia was the most frequent treatment-limiting adverse effect. In vitro studies which combine quinupristin/dalfopristin with ampicillin or doxycyline have shown enhanced killing effects against VRE; however, the clinical use of combined therapy remains unestablished. Linezolid, an oxazolidinone compound that acts by inhibiting the bacterial pre-translational initiation complex formation, has bacteriostatic activity against both vancomycin resistant E. faecium (MIC(90) = 2 to 4 microg/ml) and E. faecalis (MIC(90) = 2 to 4 microg/ml). This agent was studied in a similar emergency use protocol for multi-resistant Gram-positive infections. 55 of 133 evaluable patients were infected with VRE. Cure rates for the most common sites were complicated skin and soft tissue 87.5% (7/8), primary bacteraemia 90.9% (10/11), peritonitis 91.7% (11/12), other abdominal/pelvic infections 91.7% (11/12), and catheter-related bacteraemia 100% (9/9). There was an all-site response rate of 92.6% (50/54). In a separate blinded, randomised, multicentre trial for VRE infection at a variety of sites, intravenous low dose linezolid (200mg every 12 hours) was compared to high dose therapy (600 mg every 12 hours) with optional conversion to oral administration. A positive dose response (although statistically nonsignificant) was seen with a 67% (39/58) and 52% (24/46) cure rate in the high- and low-dose groups, respectively. Adverse effects of linezolid therapy have been predominantly gastrointestinal (nausea, vomiting, diarrhoea), headache and taste alteration. Reports of thrombocytopenia appear to be limited to patients receiving somewhat longer courses of treatment (>14 to 21 days). Linezolid resistance (MIC > or = 8 microg/ml) has been reported in a small number of E. faecium strains which appears to be secondary to a base-pair mutation in the genome encoding for the bacterial 23S ribosome binding site. At present a comparative study between the two approved agents for VRE (quinupristin/dalfopristin and linezolid) has not been performed. Several investigational agents are currently in phase II or III trials for VRE infection. This category includes daptomycin (an acidic lipopeptide), oritavancin (LY-333328; a glycopeptide), and tigilcycline (GAR-936; a novel analogue of minocycline). Finally, strategies to suppress or eradicate the VRE intestinal reservoir have been reported for the combination of oral doxycyline plus bacitracin and oral ramoplanin (a novel glycolipodepsipeptide). If successful, a likely application of such an approach is the reduction of VRE infection during high risk periods in high risk patient groups such as the post-chemotherapy neutropenic nadir or early post-solid abdominal organ transplantation.