Screening of Antibacterial Activity of South Brazilian Baccharis. Species

Abstract

South Brazilian Baccharis. species were studied for antibacterial activities against Gram-positive and Gram-negative bacteria using disk diffusion and broth dilution assays. The results showed that the n.-BuOH fraction (100 µg) from Baccharis usterii. Heering exhibited inhibitory activity against Staphylococcus aureus., Enterococcus faecalis., and Enterococcus faecium.. The n.-BuOH fraction of Baccharis spicata. (Lam.) Bailon (1000 µg) was effective against S. aureus., Escherichia coli., Enterococcus faecalis., and Enterococcus faecium.. The crude extract of Baccharis trimera. (Less) A. P. de Candolle (in doses of 1000 µ/disc) showed activity against S. aureus.. The minimum bactericidal concentration (MBC) obtained from n.-BuOH fraction of B. spicata. were 50 mg/ml against S. aureus., E. coli., E. faecalis., and E. faecium.. From the crude extract of B. trimera., a MBC of 25 mg/ml was obtained against S. aureus.. The n.-BuOH fraction of B. usterii. showed a MBC of 25 mg/ml against S. aureus. and 50 mg/ml against E. faecalis. and E. faecium., while the crude extract of this plant showed a MBC of 12.5 mg/ml against S. aureus..     

In Vitro Evaluation of High-Level,Gentamicin-Resistant Enterococci Isolated from Bacteremic Patients

We attempted to characterize the susceptibility of high-level, gentamicin-resistant (HLGR, minimum inhibitory concentration [MIC] >2000 μg/ml) enterococcal blood isolates and evaluated a small subset of these isolates for bactericidal synergy. Thirteen Enterococcus faecalis and three Enterococcus faecium isolates that were HLGR were prospectively collected. Standard broth macrodilution techniques were used to determine the MICs and minimum bactericidal concentrations to a variety of antibiotics. Two isolates were evaluated for synergy by time-kill curve methods using combinations of penicillin and streptomycin, teicoplanin and rifampin, and vancomycin and ciprofloxacin. Teicoplanin was the most active antibiotic tested, with all isolates exhibiting susceptibility to this agent. Four E. faecalis isolates and one E. faecium isolate expressed only low-level resistance to streptomycin (LLSR, MlCs 32–64 μg/ml). Penicillin and streptomycin produced bactericidal synergy in the LLSR isolate. The other antibiotic combinations did not result in bactericidal synergy in the two isolates tested. For HLGR enterococci that are only LLSR, the combination of penicillin-streptomycin appears to provide adequate bactericidal activity. Teicoplanin may potentially be useful for streptomycin-resistant HLGR isolates.     

Daptomycin for the treatment of enterococcal bacteraemia: results from the Cubicin Outcomes Registry and Experience (CORE)

Enterococcal infections are a common cause of nosocomial bloodstream infections. Vancomycin resistance and the emergence of linezolid resistance necessitate alternative therapies. Studies in vitro as well as animal and case studies suggest that daptomycin may be effective in enterococcal infections. Patients with positive blood cultures for enterococci in the Cubicin^® Outcomes Registry and Experience (CORE) 2005–2006 were identified. Patients with endocarditis, intracardiac foreign body infections or non-speciated enterococci were excluded. Outcome was assessed using protocol-defined criteria. Of 159 patients included in the efficacy population, Enterococcus faecium and Enterococcus faecalis were isolated in 120 (75.5%) and 39 (24.5%) patients, respectively. Vancomycin resistance was detected in 91% and 23% of patients with E. faecium and E. faecalis infections, respectively. Prior to daptomycin, 94/159 (59.1%) and 35/159 (22.0%) patients had received vancomycin and linezolid, respectively. Daptomycin was first-line therapy in 27/159 cases (17%). Success was observed in 139/159 patients (87%) and in 104/120 (87%) and 35/39 (90%) patients with E. faecium and E. faecalis infections, respectively. Among the safety population (n = 211), 20 (9.5%) experienced 28 adverse events possibly related to daptomycin, 8 of which were considered serious. Daptomycin may be a useful agent for treating enterococcal bacteraemia caused by E. faecium or E. faecalis. Further studies are warranted.     

High rates of colonisation by ampicillin-resistant enterococci in residents of long-term care facilities in Porto,Portugal

This study evaluated the occurrence of enterococci resistant to clinically relevant antibiotics in long-term care facility (LTCF) residents in Porto, Portugal, a region with high rates of multidrug-resistant enterococci in infected patients and healthy carriers. Faecal samples from 48 residents in two LTCFs (2015–2016) were enriched (with/without antibiotics) and plated on Slanetz–Bartley with/without the same antibiotics (ampicillin/vancomycin/linezolid). Two colonies per morphology/sample were selected for susceptibility testing and species identification. Clonality was established by PFGE and MLST. Genes coding for vancomycin resistance (vanA/vanB), virulence and plasmids (replicases) were searched by PCR. A total of 285 isolates were obtained, comprising Enterococcus faecalis, Enterococcus faecium, Enterococcus raffinosus and Enterococcus avium colonising 83%, 77%, 27% and 10% of residents, respectively. Residents from both LTCFs were colonised with vancomycin-resistant E. faecium (VanA-VREfm) (4 residents; 8%) and/or ampicillin-resistant (AmpR) (24 residents; 50%) E. raffinosus, E. faecium and E. avium. Enterococcus faecium previously associated with major human clonal lineages (ST18/ST78) or animal clones (ST393) were identified. Some PFGE types of E. faecium, E. raffinosus and E. avium were shared by residents of both LTCFs. Recent antibiotic exposure was significantly associated with colonisation by AmpR enterococci. Residents from Portuguese LTCFs were colonised with high rates of AmpR enterococci and similar rates of VREfm compared with other EU countries. A high colonisation rate with widespread enterococcal lineages that could be selected by antibiotic consumption in LTCFs was uncovered. These findings suggest that antimicrobial stewardship is warranted in LTCFs, which constitutes a significant challenge in a home-based setting.     

Characteristics of clinical and environmental vanM-carrying vancomycin-resistant enterococci isolates from an infected patient

vanM, an uncommon glycopeptide resistance gene, was first identified in an Enterococcus faecium isolate (Efm-HS0661) from Shanghai, China, in 2006 and has been predominant in this city since 2011. A vanM-carrying E. faecium was isolated from the bloodstream of a patient in an intensive care unit (ICU) in Hangzhou, China, in 2014. Further surveillance screening of a rectal swab and environmental surfaces of the patient yielded a large number of vanM-positive E. faecium. These isolates (including 1 from the bloodstream, 1 from the rectal swab and 43 representative isolates from environmental samples) were classified into four pulsed-field gel electrophoresis (PFGE) patterns and two sequence types (ST78 and ST564). PCR amplification and sequence analysis indicated that the genetic structure surrounding the vanM gene of these isolates was similar to that of the original vanM-carrying isolate Efm-HS0661. This study highlights the emergence of infections and environmental contamination caused by vanM-carrying E. faecium in an ICU of another Chinese city outside of Shanghai.     

High-level ciprofloxacin resistance among hospital-adapted Enterococcus faecium (CC17)

Hospital-adapted Enterococcus faecium differ from their colonising variants in humans and animals by additional genomic content. Molecular typing based on multilocus sequence typing (MLST) allows allocation of isolates to specific clonal complexes (CCs), such as CC17 for hospital-adapted strains. Acquired ampicillin resistance is a specific feature of these hospital isolates, especially in Europe. A few recent reports have described acquired high-level ciprofloxacin resistance as a supposed feature of hospital-adapted E. faecium strains. In the present retrospective analysis, ciprofloxacin minimum inhibitory concentrations (MICs) of 609 clinical isolates from German hospital patients (1997–2007) were determined and a breakpoint for high-level resistance was deduced (>16 mg/L). Acquired high-level ciprofloxacin resistance was distributed among isolates of 26 different MLST types (all CC17), indicating a wide prevalence of this acquired resistance trait among the hospital-adapted E. faecium population. High-level ciprofloxacin resistance was linked to gyrA and parC mutations in 98 investigated isolates. Eleven different allele types or combinations thereof were identified. Their allocation to specific MLST and pulsed-field gel electrophoresis (PFGE) types revealed differences in the emergence and spread of corresponding mutations and strains.     

Prevalence and molecular mechanism of macrolide resistance in β-haemolytic streptococci in The Netherlands

The prevalence of resistance to erythromycin and clindamycin as well as the presence of the resistance genes mef(A), mef(E), erm(A) and erm(B) were determined in 1076 consecutive isolates of β-haemolytic streptococci of Lancefield groups A (n = 219), B (n = 562), C (n = 58) and G (n = 237) collected during 2005 and 2006. The prevalence of macrolide resistance was highest in group C streptococci (6.9%), followed by group B (5.3%), group G (4.6%) and group A (1.4%). Eighty-eight percent of resistance was mediated by erm(A) and erm(B) genes. Macrolide resistance in β-haemolytic streptococci in The Netherlands is low, but increasing macrolide resistance was observed in group B streptococci.     

Spread of vancomycin-resistant Enterococcus faecium in two haematological centres in Russia

This paper describes the clonal diversity of vancomycin-resistant Enterococcus faecium isolated from patients with haematological malignancies in Russia. Pulsed-field gel electrophoresis (PFGE) typing of 129 vanA-positive E. faecium strains revealed 23 independent restriction profiles with two predominant clonal types. Multilocus sequence typing (MLST) of 16 strains selected from two predominant PFGE types showed that they belong to the epidemic clonal complex (CC) 17. Tn1546-like elements of isolates were compared with the prototype element from E. faecium BM4147 by polymerase chain reaction (PCR). Four different Tn1546 types were distinguished according to structural alternations. Polymorphism in the orf1 and vanSH genes was detected. However, a significant prevalence of the prototype Tn1546 was revealed. Tn1546-like elements with the same structures were observed in strains of different PFGE types. The virulence genes esp, gelE and hyl were detected by PCR in 118 isolates (91%), 87 isolates (67%) and 35 isolates (27%), respectively. In contrast, agg and cylA genes were not found. The detection frequency of esp was higher in epidemic strains than in sporadic ones (100% vs. 56%; P < 0.05). This study describes a genetically variable population of vancomycin-resistant E. faecium in two Russian haematological centres. The spread of vancomycin resistance was mostly due to the distribution of the two subclones of E. faecium CC17, enriched with the virulence marker esp. At the same time, dissemination of an altered Tn1546 also occurred.     

Enhancement of Vancomycin Activity by Phenothiazines against Vancomycin‐Resistant Enterococcus Faecium in vitro

Abstract: The antimicrobial and resistance‐reversal activities of seven phenothiazine derivatives were evaluated against vancomycin‐sensitive Enterococcus faecalis ATCC 29212, vancomycin resistant E. faecalis ATCC 51299 and ten vancomycin‐resistant E. faecium strains originating from human infections. Minimum inhibitory concentrations (MIC) of the compounds were determined by agar dilution method, and synergy between phenothiazines and vancomycin was investigated using Checkerboard (microbroth dilution) technique. We found that all enterococci strains, regardless of their susceptibility to vancomycin, were inhibited by phenothiazines at concentrations varying from 8 to 256 μg/ml, with thiethylperazine being the most potent inhibitory agent. Besides, all the phenothiazines showed partial synergy with vancomycin and could lessen MIC of vancomycin from 512 to 8 μg/ml at their sub‐inhibitory concentrations. The highest reduction in MIC was observed with chlorpromazine (32 times); however, thiethylperazine and promethazine stood next (24 times). Although resistance modification was observed at concentrations higher than those that phenothiazines reach in vivo, the potential offered by non‐antibiotics justify further animal experiments as well as clinical trials to establish their clinical relevance.     

Teicoplanin for treating enterococcal infective endocarditis: A retrospective observational study from a referral centre in Spain

This study aimed to evaluate the effectiveness and safety of teicoplanin for treating enterococcal infective endocarditis (EIE). A retrospective analysis of a prospective cohort of definite EIE patients treated with teicoplanin in a Spanish referral centre (2000–2017) was performed. The primary outcome was mortality during treatment. Secondary outcomes were mortality during 3-month follow-up, adverse effects and relapse. A total of 22 patients received teicoplanin, 9 (40.9%) as first-line (8 Enterococcus faecium and 1 Enterococcus faecalis) and 13 (59.1%) as salvage therapy (13 E. faecalis). Median (IQR) age was 71.5 (58.3–78) years and Charlson comorbidity index was 4.5 (3–7). Five (22.7%) affected prosthetic valves. Median duration of treatment in survivors was 53 (42.5–61) days for antibiotics and 27 (17–41.5) days for teicoplanin [median dose 10 (10–10.8) mg/kg/day]. Reasons for teicoplanin use were resistance to β-lactams (40.9%), adverse events with previous regimens (31.8%) and outpatient parenteral antimicrobial therapy (OPAT) (27.3%). Teicoplanin was withdrawn due to adverse events in 2 patients (9.1%). Five patients (22.7%) died during treatment: four in the first-line (three with surgery indicated but not performed) and one in the salvage therapy group (surgery indicated but not performed). Two deaths (11.8%) occurred over the 3-month follow-up. There were no relapses during a median of 43.2 (22.1–69.1) months. Teicoplanin can be used as an alternative treatment for susceptible E. faecium IE and as a salvage therapy in selected patients with E. faecalis IE when adverse events develop with standard regimens or to allow OPAT.     

2017年福州市第二医院病原菌的分布及耐药性分析

目的 了解2017年福州市第二医院临床分离病原菌的分布及对抗菌药物的敏感性,为临床用药提供指导。方法 共收集2 720株非重复分离菌,采用纸片扩散法或自动化仪器法进行药敏试验,按CLSI标准判读药敏结果。结果 2 720株细菌中,标本主要来源于伤口分泌物（989株）,占36.3%。革兰阴性菌1 786株,占65.7%,主要为大肠埃希菌、肺炎克雷伯菌、铜绿假单胞菌、鲍曼不动杆菌、嗜麦芽窄食单胞菌和阴沟肠杆菌;革兰阳性菌934株,占34.3%,主要为金黄色葡萄球菌、粪肠球菌和凝固酶阴性葡萄球菌。耐甲氧西林耐药株金黄色葡萄球菌、凝固酶阴性葡萄球菌的检出率分别为42.7%、84.2%。未发现对万古霉素、替考拉宁和利奈唑胺耐药的葡萄球菌。粪肠球菌对大多数抗菌药物的耐药率明显低于屎肠球菌。肠球菌属中未发现万古霉素、利奈唑胺、替考拉宁耐药的肠球菌。除对黏菌素100%敏感外,铜绿假单胞菌对其他常见抗菌药物的耐药率均较低,鲍曼不动杆菌除对黏菌素敏感外,对其他药物的耐药性均较高,均达46.2%以上。结论 2017年福州市第二医院病原菌耐药形势依旧严峻,应加强合理用药,避免交叉感染。     

Bacteriocin production and distribution of bacteriocin-encoding genes in enterococci from dogs

Many enterococcal strains produce bacteriocins, which could be useful as natural food preservatives through inhibition of pathogenic and spoilage microorganisms. There is little knowledge of the distribution and spectrum of bacteriocin activity and the distribution of bacteriocin-encoding genes in enterococci isolated from dogs. Therefore, we subjected 160 enterococcal isolates (E. faecium n=92, E. faecalis n=35, E. hirae n=28, E. casseliflavus n=3, E. mundtii n=2) from 105 samples of dog faeces to polymerase chain reaction (PCR) detection of genes for enterocin A, P, B, L50A, L50B, AS-48, and bac31 and to screening for bacteriocin activity. The results showed the presence of at least one of the tested genes in 54/160 isolates, with E. faecium the most common gene-possessing species. The most frequently occurring gene for production of enterocin A was observed in combination with enterocin P and B. Bacteriocin activity was observed in 76/160 isolates against at least one of 5 indicator bacteria from the genus Listeria, Enterococcus, Streptococcus and Staphylococcus. Four selected strains (IK25, Bri, I/Dz, P10) were active mostly against different species of Enterococcus (in the range 400-25 600 AU/mL) and Listeria sp. (800-12 800 AU/mL) but no Gram-negative bacteria were inhibited. Protein character, thermostability (up to 121°C) and stability at different pH values (3.0–10.0) were confirmed for crude bacteriocins of these four strains. The antimicrobial substance of E. faecium IK25 strain was identified as enterocin B using molecular weight detection and the presence of genes.     

2015—2019年天津医科大学肿瘤医院恶性肿瘤患者血流感染病原菌分布及耐药性分析

目的 探讨天津医科大学肿瘤医院恶性肿瘤患者血流感染病原菌分布及耐药情况,为临床合理用药提供理论依据。方法 对2015—2019年天津医科大学肿瘤医院血培养结果进行回顾性分析。结果 2015年1月—2019年12月天津医科大学肿瘤医院经血培养分离出菌株1 471株,在科室分布方面,肝胆胰腺肿瘤科、胃肠肿瘤科、血液肿瘤科占比均超过10%;在病原菌分布方面,革兰阴性菌占67.7%;革兰阳性菌占28.1%;真菌占4.1%。革兰阴性菌以大肠埃希菌、肺炎克雷伯菌、阴沟肠杆菌为主;革兰阳性菌中,以金黄色葡萄球菌、表皮葡萄球菌、粪肠球菌、屎肠球菌为主;在耐药性方面,碳青霉烯类、哌拉西林他唑巴坦、氟喹诺酮类、阿米卡星对主要肠杆菌科细菌保持良好的敏感性。葡萄球菌属中,表皮葡萄球菌中甲氧西林耐药菌株检出率高于金黄色葡萄球菌,表皮葡萄球菌整体耐药率高于金黄色葡萄球菌。肠球菌属中,屎肠球菌的整体耐药率高于粪肠球菌。结论 天津医科大学肿瘤医院肿瘤患者血流感染的病原菌以革兰阴性菌为主,与其他肿瘤医院报道一致。耐药率低于2019年CHINET三甲医院细菌耐药监测数据。     

Vancomycin-resistant <Emphasis Type="Italic">Enterococcus faecium</Emphasis>-associated encephalitis and concurrent cerebellitis

Enterococci are uncommon etiologic agents of central nervous system infections. We describe a case of nosocomial encephalitis and concurrent cerebellitis associated with Enterococcus faecium in a man, with extranodal natural killer/T-cell lymphoma, nasal type, who underwent high-dose chemotherapy and autologous peripheral blood stem cell transplantation. Brain magnetic resonance images showed lesions in the bihemispheral cerebellar cortex with swelling and several small lesions in both cerebral hemispheres. The blood and cerebrospinal fluid cultures were positive for vancomycin-resistant E. faecium. Vancomycin-resistant E. faecium can cause encephalitis and concurrent cerebellitis in an immunocompromised patient who underwent autologous peripheral blood stem cell transplantation.     

2016年中国医科大学附属盛京医院泌尿外科病原菌的分布及耐药性分析

目的 了解2016年1-12月中国医科大学附属盛京医院泌尿外科住院患者感染的主要病原菌分布及其耐药性,为临床感染患者抗生素的合理应用提供参考依据。方法 回顾性分析2016年1-12月中国医科大学附属盛京医院泌尿外科住院患者感染的主要病原菌分布及其耐药性。结果 共分离出495株病原菌,其中革兰阴性菌有312株,占63.03%,主要为大肠埃希菌、肺炎克雷伯菌、奇异变形杆菌和铜绿假单胞菌;共分离出革兰阳性菌180株,占36.37%,主要为粪肠球菌、屎肠球菌和表皮葡萄球菌;共分离出真菌3株,占0.6%。大肠埃希菌对氨苄西林、哌拉西林以及头孢唑啉的耐药率均大于80%,对厄他培南、美罗培南的耐药率较低。肺炎克雷伯菌对头孢噻肟、头孢唑啉、氨苄西林、哌拉西林的耐药率均在70%以上,而对厄他培南、美罗培南的耐药率为0。奇异变形杆菌对氨苄西林、呋喃妥因、复方新诺明、四环素的耐药率在70%以上,未检出对阿米卡星、厄他培南、美罗培南、哌拉西林/他唑巴坦、头孢他啶、头孢替坦、妥布霉素、亚胺培南耐药的菌株。铜绿假单胞菌对氨苄西林、氨苄西林/舒巴坦、厄他培南、头孢曲松、头孢替坦、头孢唑林及呋喃妥因等抗生素耐药率为100%;未检出对氨曲南、美罗培南、哌拉西林、头孢吡肟、头孢他啶耐药的菌株。粪肠球菌对克林霉素、喹努普汀/达福普汀的耐药率为100%,未检出对呋喃妥因、氯霉素、替考拉宁、替加环素、万古霉素耐药的菌株。屎肠球菌对红霉素、克林霉素、利福平和青霉素G的耐药率为100%,未检出对利奈唑胺和替加环素耐药的菌株。表皮葡萄球菌对青霉素G的耐药率为100%,未检出对利奈唑胺、喹努普汀/达福普汀、替加环素、呋喃妥因和万古霉素耐药的菌株。结论 中国医科大学附属盛京医院泌尿外科患者感染病原菌中分离率最高的为革兰阴性菌,临床医师应根据药敏结果指导抗生素的应用,有效控制感染并且延缓耐药菌的产生。     

Molecular analysis of constitutive mutations in <Emphasis Type="Italic">ermB</Emphasis> and <Emphasis Type="Italic">ermA</Emphasis> selected <Emphasis Type="Italic">In Vitro</Emphasis> from inducibly MLS<Subscript>B</Subscript>-resistant enterococci

Frequencies of spontaneous mutation from inducible resistance to constitutive resistance were determined for the four clinical isolates of erythromycin-resistant enterococci, including one isolate with ermB gene and three clinical isolates with ermA gene. The rate of ermB mutation was higher than that of ermA mutation by more than 10 fold. Sequence analysis of the regulatory regions of erm genes revealed that mutation type of ermB was just point mutation, by contraries the mutation type of ermA was either deletion or tandem duplication. These results showed distinct characteristics in mutation patterns of ermB and ermA.     

2017-2018年天津市儿童医院泌尿道感染病原菌分布及耐药性分析

目的 分析2017-2018年天津市儿童医院泌尿道感染病原菌的分布和耐药性,为临床合理应用抗菌药物提供依据。方法 收集2017年1月-2018年12月在天津市儿童医院住院,经尿液培养病原菌阳性的泌尿道感染患儿的病例资料,统计并分析泌尿道感染的病原菌分布和耐药情况。结果 共检出667株病原菌,泌尿道感染患儿主要集中于28 d~1岁,构成比为57.9%;科室以肾脏科为主,构成比为56.3%。其中革兰阳性菌320株,占48.0%,主要为屎肠球菌、粪肠球菌、鹑鸡肠球菌和鸟肠球菌;革兰阴性菌337株,占50.5%,主要为大肠埃希菌、肺炎克雷伯菌、变形杆菌属和铜绿假单胞菌;真菌10株,占1.5%。屎肠球菌对氨苄西林、苄青霉素的耐药率为100.0%,粪肠球菌对氨苄西林、呋喃妥因、利奈唑胺、苄青霉素和万古霉素的耐药率为0;鹑鸡肠球菌对氨苄西林、苄青霉素和四环素的耐药率为100.0%;鸟肠球菌对呋喃妥因、左氧氟沙星、利奈唑胺、莫西沙星和万古霉素的耐药率为0。大肠埃希菌对呋喃妥因、阿米卡星的耐药率为0;肺炎克雷伯菌对氨苄西林的耐药率为100.0%;变形杆菌属对头孢他啶、头孢替坦、美罗培南、哌拉西林/他唑巴坦和氨曲南等耐药率为0;铜绿假单胞菌对美罗培南的耐药率为0。产超广谱β内酰胺酶（ESBLs）大肠埃希菌和肺炎克雷伯菌对多种抗生素均耐药。结论 泌尿道感染的病原菌不同且多样,临床经验用药时应根据病原体耐药情况及患儿个体本身选择不同的抗菌药物,提高治疗的针对性。     

Molecular characterization and evolution of the first outbreak of vancomycin-resistant Enterococcus faecium in Western Australia

The first outbreak of vancomycin-resistant Enterococcus faecium (VREfm) in Western Australia was recorded in 2001. A state-wide infection control effort that oversaw patient screening and transfers successfully terminated the outbreak within six months; however, the outbreak re-emerged two years later. Over the two outbreaks, the vanB-positive multilocus sequence type (ST) 173 E. faecium strain was isolated from 201 patients.Our objective was to identify differences in genetic traits leading to successful transmission of ST173 VREfm compared with non-ST173 VREfm isolated during the same period. We also aimed to describe the changes observed in the ST173 VREfm genome collected during the two outbreaks.Virulence factors ecbA, fss3, psaA and scm identified in the non-ST173 isolates were largely absent in the ST173 isolates. The esp gene was not identified beyond 45% coverage for any isolate in this study. In terms of resistance genes, tet(U) was identified in 94.7% of ST173 VREfm isolated in the first outbreak but was largely absent in ST173 VREfm isolated in the second outbreak and in non-ST173 VREfm. Seven ST173 VREfm isolates (Clade A) carried dfrG but not tet(M) resistance genes. The average genome size of ST173 VREfm isolated in the first outbreak was significantly larger than the genome size of ST173 VREfm isolated in the second outbreak.The reduced number of virulence factors in ST173 isolates may explain the low infection and high colonization rates observed during the outbreak. In addition, isolates with larger genomes were found to be associated with outbreaks.     

Transfert de la résistance à la vancomycine entre entérocoques d’origine animale et humaine

Enterococci are a dominant bacterial group in the intestinal flora of humans and animals. They have emerged as important nosocomial pathogens over the last two decades, at least in part because of their intrinsic and acquired resistance to many antimicrobial agents, including vancomycin. Two main reservoirs of vancomycin resistant enterococci were described: the hospital and the animal reservoirs. It should be noted that glycopeptide avoparcin has been used as a growth promoter in animal husbandry in Europe since 1970 and an association between the incidence of vancomycin resistance in humans and avoparcin usage in animals has been suggested. In recent years, transfer of resistance genes from animal bacteria to human bacteria causes great concern. By using the vancomycin resistant enterococci, we studied genetic transfers between bacteria in vitro and in vivo in the digestive tract of germ-free mice.The horizontal transfer of vanA gene from Enterococcus faecium strains of animal origin towards E. faecium of human origin within the digestive tract is possible and occurs at high frequencies. This transfer is also possible towards Enterococcus faecalis, the predominant enterococcal species of human digestive tract, at lower frequencies. Early transfer of the vanA operon suggests that even a brief transit of enterococci of animal origin would allow resident human bacteria to acquire glycopeptide resistance, as well as other resistance genes. This transfer occurs at a lower rate in the presence of complex flora.