广州地区耐甲氧西林金黄色葡萄球菌的分子分型及耐药性分析

目的 了解广州地区耐甲氧西林金黄色葡萄球菌(methicillin-resistant Staphylococcus aureus,MRSA)分子型别及其对临床常用抗生素的耐药情况,为防控MRSA感染提供依据.方法 收集2010年10月至2011年4月广州地区两家教学医院临床分离的MRSA 142株,应用SCCmec、spa、多位点序列分型(multilocus sequence typing,MLST)、脉冲场凝胶电泳(pulsed-field gel electrophoresis,PFGE)等方法进行分子分型,检测这些菌株对苯唑西林、克林霉素等17种临床常用抗生素的药物敏感性,分析临床MRSA的耐药情况.结果 142株MRSA中121株为医院获得型金葡菌(HA-MRSA),20株为社区获得型金葡菌(CA-MRSA),1株未定型MRSA.这些MRSA可分为16种spa型,8种ST型及13种PFGE型.HA-MR-SA中的ST239-MRSA-Ⅲ-t030、ST239-MRSA-Ⅲ-t037和ST5-MRSA-Ⅱ-t002为主要流行克隆,也发现CA-MRSA中ST59-MR-SA-Ⅳ-t437克隆的流行,且这些流行克隆有特定的耐药谱.结论 广州地区流行的金葡菌仍以HA-MRSA为主,同时也有一定量的CA-MRSA检出和传播,且CA-MRSA的多重药物敏感性已在下降.     

医院和社区获得性金黄色葡萄球菌耐药性情况调查

目的 了解临床分离的社区获得性和医院获得性金黄色葡萄球菌的耐药情况,为进一步指导临床治疗,更好地控制MRSA引起的感染提供依据.方法 采用K-B纸片扩散法检测金黄色葡萄球菌对不同种类抗生素的敏感性.结果 医院获得性甲氧西林敏感金黄色葡萄球菌(HA-MSSA)对头孢唑啉、庆大霉素和左氧氟沙星的耐药率显著高于社区获得性甲氧西林敏感金黄色葡萄球菌( CA-MSSA) (P＜0.05);医院获得性耐甲氧西林金黄色葡萄球菌( HA-MRSA)对头孢唑啉、红霉素、克林霉素、四环素、庆大霉素、左氧氟沙星和利福平的耐药率显著高于CA-MSSA和HA- MSSA( P＜0.05);HA- MRSA多重耐药菌株所占的比率为90.4％,显著高于CA-MSSA的20.0％和HA-MSSA的37.4％,差异均有统计学意义(P＜0.05).结论 医院获得性金黄色葡萄球菌耐药情况较严重,CA-MSSA和HA-MSSA药物敏感性明显高HA-MRSA,HA-MRSA呈现多重耐药性.     

广州地区儿童社区获得性耐甲氧西林金黄色葡萄球菌分子特征研究

目的了解广州地区儿童患者分离的社区获得性耐甲氧西林金黄色葡萄球菌(CA-MRSA)临床分离株的分子特征。方法收集2009年—2014年我院分离获得的65株CA-MRSA临床分离株,PCR法检测杀白细胞素(PVL)基因阳性菌株,多位点基因序列类型(MLST)测定MRSA菌株的序列类型,多重PCR法对MRSA菌株进行葡萄球菌mec盒式染色体(SCCmec)分型。结果 65株CA-MRSA分离株中PVL基因阳性31株,阳性率47.69%;MLST分型表明以ST5933.84%(22/65)及ST8823.07%(15/65)为主;SCCmec分型中发现3种类型,分别为SCCmecⅡ32.30%(21/65)、SCCmecⅣ49.23%(32/65)及SCCmecⅤ18.46%(12/65),未存在未能分型菌株。结论广州地区儿童患者分离的CA-MRSA临床分离株的PVL基因阳性率相对较高,SCCmec IV型、V型可形成小范围内的流行,其基因表型存在多种ST分型。     

耐甲氧西林金黄色葡萄球菌SCCmec分型研究

目的检测耐甲氧西林金黄色葡萄球菌SCCmec基因分型,初步了解MRSA分子流行病学特征,从而进一步指导临床感染MRSA的治疗,更好地控制MRSA引起的感染,并减少耐药株的出现。方法以MRSA菌株65株为研究对象,使用多重PCR扩增技术检测SCCmec基因分型,PCR产物进行琼脂糖电泳凝胶检测,阳性株进行基因测序,与目的基因进行比对。结果65株MRSA的SCCmec基因分型均为Ⅲ型。结论我院耐甲氧西林金黄色葡萄球茵SCCmec基因分型,均为SCCmec-Ⅲ型,尚未发现CA-MRSA菌株。     

78例危重症患者医院获得性耐甲氧西林金黄色葡萄球菌肺炎的临床分析

目的探讨危重症患者医院获得性耐甲氧西林金黄色葡萄球菌(HA-MRSA)肺炎的临床特征、预后及耐药情况,以期为预防医院内耐甲氧西林金黄色葡萄球菌(MRSA)的发生和流行。方法回顾性分析该院2004年1月至2009年1月78例危重症患者医院获得性耐甲氧西林金黄色葡萄球菌的临床资料,对MRSA肺炎的易感因素、临床特征及MRSA耐药状况进行分析。结果多器官功能衰竭、住院时间长、吸烟、高龄、MRSA未清除是MRSA肺炎的独立危险因素。结论危重症患者MRSA肺炎的感染率高,应积极进行病原学监测,及时发现、隔离和治疗患者。     

耐甲氧西林金黄色葡萄球菌基因分型研究

目的 了解本地区耐甲氧西林金黄色葡萄球菌(MRSA)流行株的来源和遗传背景.方法 回顾分析华西医院127例MRSA感染者的病例资料,用SCCmec多重PCR技术、葡萄球菌A蛋白(spa)分型技术和多位点测序分型技术对其中10株MRSA临床分离株进行基因分型,并检测其杀白细胞毒素基因.结果 病例资料显示127株MRSA中3株为社区获得性MRSA(CA-MRSA),其余均为医院获得性MRSA(HA-MRSA).进行分型研究的10株MRSA中,7株HA-MRsA为SCCmecⅢ-ST239-PVL(一),呈现高度的克隆一致性,spa分型进一步显示4株为t030,另外3株为t037;CA-MRSA s19165分型为ST8-t008,与USA300属同一克隆,并且携带SCCmecⅣa和PVL基因,符合USA300一般基因特征.另外2株CA-MRSAs5301、s29635均为SCCmecⅣa-ST59-t437,与我国其他地区的报道不同.结论 该院分离的MRSA仍以医院获得性为主(124/127),HA-MRSA呈现高度的克隆一致性,并与我国的主要流行株为同一克隆;分离到与美国主要CA-MRSA流行株USA300相同克隆的菌株,另外分离到的CA-MRSA ST59-t437克隆株在我国其他地区未有报道.MLST和spa分型技术是金黄色葡萄球菌分子流行病学研究的更为简便快速的方法.     

耐甲氧西林金黄色葡萄球菌抗生素耐药和耐药基因的检测

目的探讨北京地区社区感染和院内感染中金黄色葡萄球耐药情况变化。方法用琼脂稀释法检测了471株从北京地区收集的金黄色葡萄球菌对11种抗生素的敏感水平(其中422株菌株从1993年至2000年门诊脓疱疮患儿分离获得,49株从2000年烧伤病房住院患者分离获得)。用聚合酶链反应方法对上述菌株进行了mecA耐药基因的检测。结果引起社区感染的耐甲氧西林金黄色葡萄球菌(MRSA)的比率由1993年的12.2%上升至2000年的29.8%,对甲氧西林均表现为低度耐药。引起院内感染的金黄色葡萄球菌对甲氧西林的耐药率为63.3%,表现为高度耐药。所有的金黄色葡萄球菌对青霉素100%耐药,对红霉素、四环素、克林霉素和氯霉素的耐药率分别约80%、70%、60%和50%。引起社区感染的金黄色葡萄球菌中未发现庆大霉素和利福平耐药菌株,对环丙沙星的耐药率由1993年的2.4%上升至2000年的21.3%;引起院内感染的金黄色葡萄球菌中对庆大霉素、环丙沙星和利福平的耐药率分别为63.3%、63.3%和57.1%。所有的金黄色葡萄球菌均对夫西地酸和万古霉素敏感。2000年分离的多重耐药菌株比例较1993年有所增加。PCR对mecA耐药基因的测定结果显示,所有对甲氧西林高度耐药的金黄色葡萄球菌mecA耐药基因均呈阳性;对甲氧西林低度耐药的金黄色葡萄球菌mecA耐药基因均呈阴性。结论在本实验所及范围内,北京地区金黄色葡萄球菌的耐药率逐渐上升,mecA耐药基因测定是筛选耐药MRSA菌株的快速、简易手段。     

血液分离耐甲氧西林金黄色葡萄球菌的脉冲场凝胶电泳分析

目的了解我院患者血液分离耐甲氧西林金黄色葡萄球菌（MRSA）的分子流行病学特征。方法收集2006年1月-2008年12月我院患者血液分离耐甲氧西林金黄色葡萄球菌22株,采用脉冲场凝胶电泳技术进行分子分型。结果耐甲氧西林金黄色葡萄球菌可分为A-F共6个型别,其中A型13株、B型4株、C型2株,D、E、F型各1株;A型还可分为A1-A6共6个亚型,B型也可分为2个亚型。结论我院患者血液分离的耐甲氧西林金黄色葡萄球菌菌株在分子水平上有较近的亲缘关系。     

耐甲氧西林金黄色葡萄球菌的分布及耐药性分析

目的 通过对耐甲氧西林金黄色葡萄球菌的临床分布情况及耐药性分析,为临床合理使用抗菌药物提供依据,预防医院耐甲氧西林金黄色葡萄球菌感染的发生及流行.方法 收集2008年1月-2009年12月临床各类感染性标本中分离的297株金黄色葡萄球菌,采用KB法进行药敏试验,耐甲氧西林金黄色葡萄球菌的判定按2007年美国临床实验室标准委员会标准执行.结果 金黄色葡萄球菌297株中,检出耐甲氧西林金黄色葡萄球菌201株,检出率67.7%,万古霉素的敏感性100%,其他敏感性较高的药物依次为氯霉素81.6%、呋喃妥因78.6%、复方新诺明58.2%等.结论 耐甲氧西林金黄色葡萄球菌多来自呼吸道标本痰及咽拭子,并对多种抗菌药物的耐药率高,多重耐药明显,临床上应根据药敏结果,合理选用抗菌药物,减缓耐甲氧西林金黄色葡萄球菌耐药菌株产生,控制医院内感染.     

泌尿系感染中葡萄球菌的耐药性分析

目的:分析泌尿系感染中葡萄球菌的耐药性,为临床合理选用抗菌药物提供依据。方法:通过临床调查和患者标本病原学检验方法,对住院患者泌尿系金黄色葡萄球菌感染情况进行调查。分析其临床分布特点及对分离到的菌株进行药物敏感性测定。结果:在所测全部标本中,共分离出52株金黄色葡萄球菌,其中共检出耐甲氧西林金黄色葡萄球菌(MRSA)32株,占61.54%。本组52株金黄色葡萄球菌中,未发现对万古霉素和伊米配能耐药的菌株,MRSA菌株的耐药率高于甲氧西林敏感的金黄色葡萄球菌(MSSA)。结论:金黄色葡萄球菌作为泌尿系感染常见病原菌,MRSA菌株的耐药率不断上升,应重视微生物标本的送检和MRSA的主动监测,临床应加强抗菌药物使用管理。     

DNA fingerprinting of methicillin-resistant Staphylococcus aureus (MRSA) by pulsed-field gel electrophoresis (PFGE) in a teaching hospital in Malaysia

Methicillin-resistant Staphylococcus aureus (MRSA) has been prevalent in our hospital over the last three years. Differentiation among MRSA strains by DNA typing in addition to antibiotic resistance pattern surveillance is crucial in order to implement infection control measures. The aim of this study was to characterize MRSA isolates from patients admitted to Hospital Universiti Kebangsaan Malaysia (HUKM) by phenotypic (analyses of antibiotic susceptibility pattern) and genotypic (PFGE) techniques to determine the genetic relatedness of the MRSA involved and to identify endemic clonal profiles of MRSA circulating in HUKM. Seventy one MRSA strains collected between January to March 2000 from patients from various wards in HUKM were tested for antimicrobial resistance and typed by pulsed-field gel electrophoresis (PFGE). Four major types of PFGE patterns were identified (A, B, C and D) among MRSA strains. Two predominant PFGE types were recognised, Type A (59.2%) and Type B (33.8%). Most of these strains were isolated from ICU, Surgical wards and Medical wards. MRSA strains with different PFGE patterns appeared to be widespread among wards. Strains with the same antibiotype could be of different PFGE types. Most of isolates were resistant to ciprofloxacin, erythromycin, gentamicin and penicillin. One isolate with a unique PFGE pattern Type D and susceptible to gentamicin was identified as a different clone. Some isolates obtained from the same patient showed different PFGE subtypes suggesting that these patients were infected/colonized with multiple MRSA strains. PFGE analysis suggests that MRSA strains with different PFGE types was propagated within our hospital. The relationship between antibiotic susceptibility and PFGE patterns was independent. The ability of PFGE technique in differentiating our MRSA strains make it a method of choice for investigating the source, transmission and spread of nosocomial MRSA infection, and thus an appropriate control programme can be implemented to prevent the spread of MRSA infection.     

医院获得性感染中出现携带SCCmecⅣ/Ⅴ的耐甲氧西林金黄色葡萄球菌

目的 研究某院临床分离的医院获得性耐甲氧西林金黄色葡萄球菌(HA-MRSA)的葡萄球菌染色体mec盒(SCCmec)分型及分子流行病学特征.方法 收集中南大学湘雅医院2012年1月~2012年12月临床分离的71株HA-MRSA,采用多重PCR进行SCCmec分型,PCR检测PVL毒素基因,并用脉冲场凝胶电泳(PFGE)分析菌株间的同源性.结果 71株HA-MRSA以SCCmecⅢ型为主,占69.0%(49/71),其次为SCCmecⅣ型、SCCmecⅤ型和SCCmecⅡ型,分别占14.1%(10/71)、4.2%(3/71)和4.2%(3/71),另有6株(8.5%)菌株未能分型.HA-SCCmecⅣ/ⅤMRSA感染者年龄显著低于HA-SCCmecⅠ/Ⅱ/ⅢMRSA感染者,携带PVL基因阳性率显著高于HA-SCCmecⅠ/Ⅱ/ⅢMRSA感染者,而两者入院至检出菌株的时间及住院天数均未见明显差异.HA-SCCmecⅣ/ⅤMRSA对左旋氧氟沙星、环丙沙星、利福平、庆大霉素、四环素等的耐药率均显著低于HA-SCCmecⅠ/Ⅱ/ⅢMRSA(P<0.05).13株HA-SCCmecⅣ/ⅤMRSA菌株在55%的相似度水平形成一个大的组群.按照≥85%的相似度,这些菌株共形成3个PFGE簇以及4个单一菌株的PFGE型.结论 在国内首次发现携带SCCmecⅤ型的HA-MRSA菌株,HA-SCCmecⅣ/ⅤMRSA已有在医疗机构传播的趋势,并成为医院内感染的重要来源.     

Antimicrobial resistance and molecular epidemiological characteristics of clinical isolates of Staphylococcus aureus in Changsha area

Background  Increasing prevalence of Staphylococcus aureus (S. aureus), particularly methicillin-resistant S. aureus (MRSA) has been reported in China. In this study, we investigated the drug resistance characteristic, genetic background, and molecular epidemiological characteristic of S. aureus in Changsha.

Methods  Between January 2006 and December 2008, 293 clinical isolates of S. aureus were collected from 11 hospitals in Changsha and identified by the Vitek-2 system. All the isolates were verified as MRSA by PCR amplification of both femA and mecA genes. K-B disk method was used to test drug sensitivity of S. aureus to antibiotics. Pulsed-field gel electrophoresis (PFGE) was performed for genotypic and homologous analysis of 115 isolates randomly selected from the original 293 clinical S. aureus isolates.

Results  S. aureus was highly resistant to penicillin, ampicillin, erythromycin, and clindamycin with resistant rates of 96.6%, 96.6%, 77.1%, and 67.2% respectively. All the isolates were susceptible to tecoplanin, vancomycin, and linezolid. MRSA accounted for 64.8% (190/293) of all the S. aureus strains. The 115 S. aureus isolates were clustered into 39 PFGE types by PFGE typing, with 13 predominant patterns (designated types A to M) accounting for 89 isolates. The most prevalent PFGE type was type A (n=56, 48.7%) and 100.0% of type A strains were MRSA. PFGE type A included 13 subtypes, and the most prevalent subtype was subtype A1 (46.4%, 26/56). Strains with PFGE type A were isolated from eight hospitals (8/11), and both subtypes A1 and A4 strains were isolated in a university hospital.

Conclusions  Clinical isolates of S. aureus in Changsha were resistant to multiple traditional antibiotics. There was an outbreak of PFGE type A MRSA in this area and the A1 subtype was the predominant epidemic clone. Dissemination of the same clone was an important reason for the wide spread of MRSA.     

Incidence of Community-associated Methicillin-resistant Staphylococcus aureus Infections in a Regional Hospital

Background and Objective: Since the early 2000s, the incidence of methicillin-resistant Staphylococcus aureus (MRSA) infections among the community of people lacking known healthcare risk factors has increased. This MRSA infection is referred to as community-associated MRSA (CA-MRSA) infection and is distinct from hospital-associated MRSA (HA-MRSA) infection, which occurs among people with known healthcare risk factors. Understanding the epidemiology of CA-MRSA infections is critical; however, this has not been investigated in detail in Japan. Our objective was to investigate the incidence of CA-MRSA infections in a regional hospital.Patients and Methods: We investigated CA-MRSA isolates and infections in a rural regional hospital by reviewing medical records of one year. Infections were classified as CA-MRSA if no established risk factors were identified.Results: During 2008, 31 Staphylococcus aureus (S. aureus) isolates were detected in 29 unique patients, with 1 methicillin-sensitive S. aureus (MSSA) isolates obtained from 19 patients (66%) and MRSA obtained from 10 patients (34%). In the 10 patients with MRSA, the number of HA-MRSA and CA-MRSA cases were nine (32% of patients with S. aureus isolates) and one (3%), respectively. The patient with CA-MRSA was diagnosed with cellulitis due to CA-MRSA. All nine patients with HA-MRSA exhibited colonization.Conclusion: We observed a CA-MRSA case in a regional hospital in Japan, suggesting that incidence trends of CA-MRSA should be considered in future research and treatment.     

Methicillin-resistant Staphylococcus aureus in the Australian community: an evolving epidemic

OBJECTIVE: To describe antimicrobial resistance and molecular epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) isolated in community settings in Australia. DESIGN AND SETTING: Survey of S. aureus isolates collected prospectively Australia-wide between July 2004 and February 2005; results were compared with those of similar surveys conducted in 2000 and 2002. Main outcome measures: Up to 100 consecutive, unique clinical isolates of S. aureus from outpatient settings were collected at each of 22 teaching hospital and five private laboratories from cities in all Australian states and territories. They were characterised by antimicrobial susceptibilities (by agar dilution methods), coagulase gene typing, pulsed-field gel electrophoresis, multilocus sequence typing, SCCmec typing and polymerase chain reaction tests for Panton-Valentine leukocidin (PVL) gene. RESULTS: 2652 S. aureus isolates were collected, of which 395 (14.9%) were MRSA. The number of community-associated MRSA (CA-MRSA) isolates rose from 4.7% (118/2498) of S. aureus isolates in 2000 to 7.3% (194/2652) in 2004 (P = 0.001). Of the three major CA-MRSA strains, WA-1 constituted 45/257 (18%) of MRSA in 2000 and 64/395 (16%) in 2004 (P = 0.89), while the Queensland (QLD) strain increased from 13/257 (5%) to 58/395 (15%) (P = 0.0004), and the south-west Pacific (SWP) strain decreased from 33/257 (13%) to 26/395 (7%) (P = 0.01). PVL genes were detected in 90/195 (46%) of CA-MRSA strains, including 5/64 (8%) of WA-1, 56/58 (97%) of QLD, and 25/26 (96%) of SWP strains. Among health care-associated MRSA strains, all AUS-2 and AUS-3 isolates were multidrug-resistant, and UK EMRSA-15 isolates were resistant to ciprofloxacin and erythromycin (50%) or to ciprofloxacin alone (44%). Almost all (98%) of CA-MRSA strains were non-multiresistant. CONCLUSIONS: Community-onset MRSA continues to spread throughout Australia. The hypervirulence determinant PVL is often found in two of the most common CA-MRSA strains. The rapid changes in prevalence emphasise the importance of ongoing surveillance.     

Carriage of methicillin-resistant Staphylococcus aureus in a Queensland Indigenous community

OBJECTIVE: To determine the prevalence of community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) carriage and infection among children living in an Indigenous community in Queensland. DESIGN, SETTING AND PARTICIPANTS: Swabs for culture of S. aureus were collected from the nose, throat and skin wounds of primary school children. MAIN OUTCOME MEASURES: MRSA carriage, antibiotic sensitivity, genotype, and presence of the virulence factor Panton-Valentine leukocidin (PVL); and epidemiological risk factors for MRSA carriage. RESULTS: 92 (59%) of 157 eligible children were included in the study. Twenty-seven (29%) carried S. aureus; 14 of these (15% of total) carried MRSA. MRSA was isolated from 29% of wound swabs, 8% of nose swabs, and 1% of throat swabs. Fourteen of 15 MRSA isolates were sensitive to all non-beta-lactam antibiotics tested. Eight children (9%) carried CA-MRSA clonal types: six carried the Queensland clone (ST93), and two carried the South West Pacific clone (ST30). All these isolates carried the virulence factor PVL. The remaining six children carried a hospital-associated MRSA strain (ST5), negative for PVL. CONCLUSIONS: We have identified a high prevalence of CA-MRSA carriage in school children from a Queensland Indigenous community. In this setting, antibiotics with activity against CA-MRSA should be considered for empiric therapy of suspected staphylococcal infection. Larger community-based studies are needed to improve our understanding of the epidemiology of CA-MRSA, and to assist in the development of therapeutic guidelines for this important infection.     

Detection and molecular typing of methicillin-resistant Staphylococcus aureus from northeastern part of India

BackgroundIn Staphylococcus aureus, methicillin resistance is exhibited by modifications in penicillin-binding protein that minimises the binding affinity to beta-lactam antibiotics. The present study investigated the occurrence of methicillin-resistant S. aureus (MRSA) in community-acquired infections, that is, community-acquired MRSA (CA-MRSA) and in-hospital–acquired infections, that is, hospital-acquired MRSA (HA-MRSA) from Northeast India.MethodsA total of 197 consecutive non-duplicate isolates were collected from Silchar Medical College and Hospital and other private diagnostic laboratories. The isolates were confirmed to be S. aureus at our centre. All isolates were subjected to antibiotic susceptibility testing and were screened for methicillin resistance using cefoxitin disc test. All MRSA were subjected to Polymerase Chain Reaction (PCR) assay for detection of mecA and mecC genes. DNA fingerprinting was performed for determining clonal diversity.ResultsSeventy-one isolates of 127 confirmed S. aureus were found to be methicillin resistant by screening test. mecA gene was detected in 43 isolates, and none of the isolates were positive for mecC gene. Linezolid and teicoplanin showed better activity with susceptibility pattern being 83.6% and 72.44%, respectively, whereas 66.14% were sensitive to vancomycin. Other antibiotic showed low level of activity. Pulsed Field Gel Electrophoresis (PFGE) showed 14 different banding patterns that suggest isolates were of different clonal types.ConclusionmecA was responsible for methicillin resistance in majority of strains. Polyclonal spread of MRSA infection in the study area indicates its diverse origin and possible lateral transfer. Thus, this study is of clinical interest in terms of selection of proper antimicrobial chemotherapy and infection control management.     

Genotypic Characterization of Methicillin-resistant Staphylococcus aureus Isolated from Pigs and Retail Foods in China

Objective To investigate the genotypic diversity of Methicillin-resistant Staphylococcus aureus (MRSA) isolated from pigs and retail foods from different geographical areas in China and further to study the routes and rates of transmission of this pathogen from animals to food. Methods Seventy-one MRSA isolates were obtained from pigs and retail foods and then characterized by multi-locus sequencing typing (MLST), spa typing, multiple-locus variable number of tandem repeat analysis (MLVA), pulsed-field gel electrophoresis (PFGE), and antimicrobial susceptibility testing. Results All isolated MRSA exhibited multi-drug resistance (MDR). Greater diversity was found in food-associated MRSA (7 STs, 8 spa types, and 10 MLVA patterns) compared to pig-associated MRSA (3 STs, 1 spa type, and 6 MLVA patterns). PFGE patterns were more diverse for pig-associated MRSA than those of food-associated isolates (40 vs. 11 pulse types). Among the pig-associated isolates, CC9-ST9-t899-MC2236 was the most prevalent clone (96.4%), and CC9-ST9-t437-MC621 (20.0%) was the predominant clone among the food-associated isolates. The CC9-ST9 isolates showed significantly higher antimicrobial resistance than other clones. Interestingly, CC398-ST398-t034 clone was identified from both pig- and food-associated isolates. Of note, some community- and hospital-associated MRSA strains (t030, t172, t1244, and t4549) were also identified as food-associated isolates. Conclusion CC9-ST9-t899-MC2236-MDR was the most predominant clone in pigs, but significant genetic diversity was observed in food-associated MRSA. Our results demonstrate the great need for improved surveillance of MRSA in livestock and food and effective prevention strategies to limit MDR-MRSA infections in China.     

儿童社区获得性耐甲氧西林金黄色葡萄球菌感染的临床特征及耐药分析

目的 总结儿童社区获得性耐甲氧西林金黄色葡萄球菌(CA-MRSA)感染的临床特征及对抗菌药物的耐药性,以提高对该病原菌感染的诊疗水平,指导抗菌药物的合理应用.方法 回顾性分析2004年1月-2010年12月CA-MRSA感染住院患儿的临床和细菌药敏资料.结果 CA-MRSA感染患儿共130例,其中男77例,女53例,男女比1.5:1,年龄2d～14岁,1岁以下72例(占55.4%),1～5岁37例(占28.5%).临床疾病以皮肤软组织感染(SSTIS)最多见,占78.5%,其次为败血症(占10.0%)、化脓性骨髓炎(占 3.8%)、肺炎(占2.3%)及脓气胸(占1.5%)等.3例有基础疾病,分别为房间隔缺损、营养不良及急性早幼粒细胞白血病.130例患儿中治愈102例(占78.5%),好转28例(占21.5%).药敏试验结果显示CA -MRSA均为多重耐药,对β内酰胺类抗生素及其酶抑制剂的复合制剂完全耐药,对红霉素和克林霉素耐药率分别为70.0%和46.2%;对左氧氟沙星、环丙沙星、利福平、庆大霉素、SMZco尚有较高敏感性,敏感率分别为92.3%、90.8%、91.5%、86.8%、72.3%,尚未发现对万古霉素及利奈唑胺耐药的菌株.结论 CA-MRSA感染好发于5岁以下尤其是1岁以内儿童,临床疾病以皮肤软组织感染多见,97.7%患儿既往体健.CA-MRSA对常用抗菌药物呈现多重耐药,但临床预后良好.     

Prevalence of inducible clindamycin resistance in Staphylococcus aureus isolated from clinical samples

Background

Therapy for Staphylococcal infections may be complicated by the possibility of inducible macrolide-lincosamide-streptogramin B resistance (MLSBi). We studied the prevalence of MLSBi in community associated (CA) and hospital associated (HA) Staphylococcus aureus isolates from clinical samples.

Methods

A total of 305 strains of S. aureus comprising 140 (45.9%) [95% CI 40.36–51.52] methicillin resistant S. aureus (MRSA) and 165 (54%) [95% CI 48.48–59.64] methicillin-sensitive S. aureus (MSSA) were identified by conventional methods. The double disc test (D test) was applied by placing erythromycin and clindamycin discs to investigate inducible and constitutive MLSBi resistant phenotypes.

Results

16.6% of MRSA showed constitutive resistance and 37.5% inducible MLSBi resistance. Community associated MRSA (CA-MRSA) represented 10% of all isolates and had lower prevalence of MLSBi than hospital associated MRSA (HA-MRSA).

Conclusion

Routine screening for inducible MLSBi resistance by double disc test can screen for potential treatment failures such that clindamycin can be used effectively and judiciously when indicated for staphylococcal infections especially for treating skin and soft tissue infections (SSTIs) in CA-MRSA due to low prevalence of MLSBi among CA-MRSA.