Staphylococcus epidermidis protease EcpA can be a deleterious component of the skin microbiome in atopic dermatitis

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苯唑西林和头孢西丁纸片扩散法现行耐药折点判断凝固酶阴性葡萄球菌甲氧西林耐药性的评价

目的 评价苯唑西林和头孢西丁纸片扩散法现行耐药折点在判断凝固酶阴性葡萄球菌（CNS）甲氧西林耐药性中的准确性。方法 苯唑西林（1μg）和头孢西丁（30μg）纸片扩散法测定149株临床分离的CNS对甲氧西林的耐药性，量取两种纸片的抑菌环直径。对苯唑西林组分别以≤14mm、≤15mm、≤16mm、≤17mm（CLSI／NCCLS2004标准）为耐药折点，对头孢西丁组分别以≤21mm、22mm、≤23mm、≤24mm（CLSI／NCCLS2004年标准）为耐药折点，与mecA基因检测结果比较，评价两种纸片扩散法在各折点对耐甲氧西林CNS判断的敏感性和特异性。结果 与mecA基因检测结果比较，苯唑西林纸片扩散法在不同的耐药折点判断耐甲氧西林表皮葡萄球菌的敏感性分别为52．3％、75．0％、90．9％、100％，特异性都为100％，判断耐甲氧西林非表皮葡萄球菌CNS的敏感性分别为66．7％、79．0％、90．1％、97．5％，特异性分别为100％、100％、100％、94．4％；头孢西丁纸片扩散法在不同耐药折点判断耐甲氧西林表皮葡萄球菌的敏感性分别为45．5％、70．1％、90．9％、100％，特异性都为100％，判断耐甲氧西林非表皮葡萄球菌CNS的敏感性分别为83．6％、91．8％、97．3％、100％，特异性都为100％。结论 苯唑西林和头孢西丁纸片扩散法检测耐甲氧西林CNS的现行耐药折点标准在判断表皮葡萄球菌和非表皮葡萄球菌CNS的甲氧西林耐药性中都有很高的敏感性和特异性，适用于CNS对甲氧西林耐药性的判断。对于非表皮葡萄球菌CNS，头孢西丁纸片扩散法较苯唑西林纸片扩散法结果更可靠。     

医院葡萄球菌属临床分离株的耐药性

目的研究葡萄球菌属的耐药趋势及变迁,以探讨临床常见葡萄球菌属分离株的耐药性现状,为葡萄球菌感染提供选药依据. 方法对2000～2003年我院临床分离的常见葡萄球菌,采用Kirby-Bauer法进行药敏试验,高盐琼脂扩散法对苯唑西林耐药的菌株做耐甲氧西林葡萄球菌(MRS)测定,按美国临床实验室标准化委员会(NCCLS)1999年标准判断结果. 结果近4年临床分离到的前9位细菌共6 602株,金黄色葡萄球菌(SAU)、凝固酶阴性葡萄球菌(CNS)分别占第2位(977株,占14.4%)和第6位(607株,占8.9%);MRSA、MRCNS的检出率分别为84%和86.3%,环丙沙星、红霉素、克林霉素、复方新诺明对其耐药率均>40%;头孢唑林对MRSA呈高度耐药(>90%),对MRCNS耐药率<40%;未发现耐万古霉素菌株. 结论近4年临床分离菌仍以革兰阴性菌为主,但SAU和CNS亦占相当比例,且MRSA和MRCNS呈高分离率,应合理使用抗菌药物及采取其他有效措施控制MRS的感染.     

荧光原位杂交法快速鉴定血培养阳性葡萄球菌的临床应用

目的快速鉴定血培养中的金黄色葡萄球菌和凝固酶阴性葡萄球菌(CoNS),结合临床快速判定是否为污染菌。方法采用荧光原位杂交法鉴定血培养中的金黄色葡萄球菌和CoNS,杂交结果若为CoNS,根据临床资料进行判断,并与文献推荐的污染判断法进行结果比较。结果探针的特异性经由标准菌株和临床分离菌株证实。金黄色葡萄球菌探针的特异性和敏感性均为100%,GoNS探针的特异性和敏感性分别为100%和95.5%。179株CoNS中117株判断为污染菌,污染率为68%,与文献推荐的污染判断方法一致。结论荧光原位杂交法适用于血培养中的金黄色葡萄球菌和CoNS的快速鉴定,以排除CoNS污染。     

凝固酶阴性葡萄球菌医院内感染与耐药性研究

对２８例院内甲氧西林耐药的凝固酶阴性葡萄球菌（ＭＲＣＮＳ）感染病例及３７例院内甲氧西林敏感的凝固酶阴性葡萄球菌（ＭＳＣＮＳ）感染病例，进行了临床和细菌学研究。结果显示，ＭＲＣＮＳ感染病例包括呼吸道感染、尿路感染、败血症、皮肤软组织感染等疾病，它们多发生在有基础疾病患者，表现为发热、纳差等症状，病死率较高。致病细菌包括表皮葡萄球菌、腐生葡萄球菌等８个菌种的葡萄球菌。耐药性研究表明，ＭＲＣＮＳ菌株占４３．１％，其对大多数抗菌药物的耐药率都比较高，但对万古霉素全部敏感。建议可选择万古霉素治疗院内ＭＲＣＮＳ感染患者。     

Clinical utility of daptomycin in infective endocarditis caused by Gram-positive cocci

Gram-positive bacteria account for >80% of all cases of endocarditis. Currently, staphylococci are the leading cause of endocarditis worldwide. Daptomycin is the drug of choice for empirical antibiotic therapy of staphylococcal endocarditis due to its optimal activity both against meticillin-susceptible Staphylococcus aureus and meticillin-resistant S. aureus (MRSA) strains. Daptomycin has not been proven to be superior to vancomycin in the treatment of MRSA endocarditis. However, daptomycin should be considered the drug of choice for the treatment of MRSA endocarditis caused by strains with a vancomycin minimum inhibitory concentration (MIC) of 2 μg/mL, for heterogeneous vancomycin-intermediate S. aureus (hVISA) phenotypes and for glycopeptide-intermediate S. aureus (GISA) strains. Daptomycin is the drug of choice for rescue therapy in cases of MRSA endocarditis in which vancomycin has failed. The appropriate dose of daptomycin has not yet been established; however, for treatment of left-sided endocarditis the dose of daptomycin should be higher than the recommended dose of 6 mg/kg/day. Combination antibiotic therapy with daptomycin (e.g. combined with fosfomycin) is a promising treatment for MRSA endocarditis and warrants further investigation. In vivo studies show that daptomycin is superior to vancomycin in the treatment of meticillin-resistant coagulase-negative staphylococci experimental endocarditis, although clinical data are required. Daptomycin could represent an efficacious treatment for vancomycin-resistant Enterococcus faecium endocarditis. Finally, the pharmacokinetic profile of daptomycin makes it an excellent drug for outpatient parenteral antimicrobial therapy.     

Clinical efficacy of teicoplanin in the treatment of bloodstream infection caused by methicillin-resistant coagulase-negative staphylococci

Empirical combination therapy with β-lactams and glycopeptides is recommended for patients with presumed staphylococcal bloodstream infection (BSI). While coagulase-negative staphylococci (CNS) remain susceptible to vancomycin, such isolates have become less susceptible to teicoplanin. The aim of this retrospective study was to evaluate the clinical efficacy of teicoplanin in the treatment of BSI caused by methicillin-resistant CNS according to teicoplanin susceptibility. Inclusion criteria were patients with intravascular-catheter related BSIs caused by methicillin-resistant CNS (positive for two or more specimens); teicoplanin therapy; and at least one of the signs or symptoms caused by BSI. Antimicrobial resistance was defined as minimum inhibitory concentration (MIC) ≥8 μg/mL. The primary efficacy endpoint was clinical success evaluated 2 weeks after the completion of teicoplanin therapy [test of cure (TOC)]. Resistant rate of CNS was 0% for vancomycin and 22.9% for teicoplanin, and geometric mean MICs were 1.31 μg/mL and 3.41 μg/mL, respectively (p < 0.001). The catheter was removed in all patients except one, and high early clinical response at 72 h after starting therapy was obtained irrespective of teicoplanin susceptibility. The clinical success rate at TOC was 60% in patients with BSIs caused by teicoplanin-resistant strains, while 90% in patients with BSIs caused by susceptible strains (p = 0.052). In multivariate analyses, teicoplanin resistance was significant factor for decreased clinical success at TOC (adjusted odds ratio 0.138, 95% confidence interval 0.020–0.961, p = 0.045). Because of the poor clinical efficacy of teicoplanin against teicoplanin-resistant CNS, combination therapy comprising vancomycin and β-lactam antibiotics should be considered in presumed staphylococci BSI.     

Use of sodA sequencing for the identification of clinical isolates of coagulase-negative staphylococci

This study evaluated the possible advantages provided by a genotypic method over commercially available biochemical systems for the identification of clinical isolates of coagulase-negative staphylococci (CNS). Partial sequencing of the sodA gene was performed for 168 coagulase-negative clinical isolates of staphylococci identified previously with the ID32 STAPH system. Of these, 101 (60.1%) were identified to the species level with ID32 STAPH, while 67 (39.9%) were misidentified or not identified with certainty. Sequencing of sodA proved useful for resolving all ambiguities or inconclusive identifications generated by the commercially available biochemical identification system.     

Wound contamination in cardiac surgery. A systematic quantitative and qualitative study of the bacterial growth in sternal wounds in cardiac surgery patients

OBJECTIVES: To investigate the degree of bacterial contamination in the sternal wound during cardiac surgery and the sternal skin flora after operation in order to increase our understanding of the pathogenesis of sternal wound infections. DESIGN: Prospective study where cultures were taken peri- and postoperatively from sternal wounds and skin. SETTING: University Hospital. PATIENTS: 201 cardiac surgery patients. RESULTS: 89% of the patients grew bacteria from the subcutaneous sternal tissue. 98% of the patients showed bacterial growth on the surrounding skin at the end of the operation. We found both commensal and nosocomial bacteria in the sternal wound. These bacteria had different temporal distribution patterns. Coagulase-negative staphylococci (CoNS) and Propionibacterium acnes (PA) were by far the most prevalent bacteria during and after the operation. Furthermore, 41% of patients had more than 10,000 CFU/pad CoNS on the skin. There was no correlation between length of operation and number of bacteria. Men displayed higher bacterial counts than women on the skin. CONCLUSION: Skin preparation with ethanol/chlorhexidine is unable to suppress the physiological skin flora for the duration of a heart operation. A decrease of CoNS and PA postoperatively can be caused by competitive recolonisation of commensal and nosocomial bacteria.