Methicillin resistant Staphylococcus aureus.

Out of 308 isolates of Staphylococcus aureus isolated from specimens processed at the Department of Microbiology, Faculty of Medicine, Colombo 66 (21.5%) were resistant to methicillin. A significantly higher proportion of methicillin resistant Staphylococcus aureus (MRSA) were isolated from special care units, namely the Premature Baby Unit (PBU) and the Plastic Surgery Unit (PSU) when compared with other general medical and surgical units. Most of these strains were also resistant to many other antibiotics. The patients with MRSA infections had a longer mean hospital stay when compared to patients with methicillin sensitive Staphylococcus aureus (MSSA) infections. MRSA strains are as virulent as MSSA strains and these infections are mainly nosocomial.     

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。     

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.     

Preliminary molecular epidemiology of the Staphylococcus aureus in lower respiratory tract infections: a multicenter study in China

Background  Staphylococcus aureus (S. aureus) remains as an important microbial pathogen resulting in community and nosocomial acquired infections with significant morbidity and mortality. Few reports for S. aureus in lower respiratory tract infections (LRTIs) have been documented. The aim of this study was to explore the molecular epidemiology of S. aureus in LRTIs in China.

Methods  A multicenter study of the molecular epidemiology of S. aureus in LRTIs was conducted in 21 hospitals in Beijing, Shanghai and twelve other provinces from November 2007 to February 2009. All the collected S. aureus strains were classified as minimum inhibitory concentration (MIC), mecA gene, virulence genes Panton-Valentine Leukocidin (PVL) and γ-hemolysin (hlg), staphylococcal cassette chromosome mec (SCCmec) type, agr type, and Multilocus Sequence Typing (MLST).

Results  Totally, nine methicillin-sensitive S. aureus (MSSA) and 29 methicillin-resistant S. aureus (MRSA) strains were isolated after culture from a total of 2829 sputums or bronchoalveolar lavages. The majority of MRSA strains (22/29) had a MIC value of ≥512 µg/ml for cefoxitin. The mecA gene acting as the conservative gene was carried by all MRSA strains. PVL genes were detected in only one S. aureus strain (2.63%, 1/38). The hlg gene was detected in almost the all S. aureus (100% in MSSA and 96.56% in MRSA strains). About 75.86% of MRSA strains carried SCCmec III. Agr type 1 was predominant (78.95%) among the identified three agr types (agr types 1, 2, and 3). Totally, ten sequence type (ST) of S. aureus strains were detected. A new sequence type (ST1445) was found besides confirming ST239 as the major sequence type (60.53%). A dendrogram generated from our own MLST database showed all the bootstrap values ≤50%.

Conclusion  Our preliminary epidemiology data show SCCmec III, ST239 and agr type 1 of S. aureus as the predominant strains in LRTIs in Mainland of China.

     

ANTIBIOTIC RESISTANCE PATTERN OF ISOLATES FROM WOUND AND SOFT TISSUE INFECTIONS

Two-hundred and eighty bacterial isolates from wound and soft tissue infections were studied for species identification and antibiotic resistance pattern. Amongst them 122 isolates were from community acquired infection and 158 were from nosocomial infections. The common community acquired pathogens were Staphylococcus aureus (67.8%) and Streptococcus pyogenes (10.7%), whereas Staphylococcus aureus (60.1%) and E. Coli (8.9%) were common in nosocomial infection. Only two anaerobes (Cl perfringens) were isolated. Penicillin resistance was found to be 87% and 92% for Staphylococccus aureus in community acquired and noscomial infections respectively. 85% of Proteus isolates were resistant to ampicillin. There was relatively lower level of resistance by all isolates to cefotaxime. Gentamicin showed higher rate of resistance than netilmicin and amikacin. Resistance of E. coli isolates to fluoroquinolones being 79% for norfloxacin, 81% for ciprofloxacin and 60% for ofloxacin. The study showed a higher resistance of methicillin resistant Staphylococcus aureus (MRSA) to other antibiotics. Amikacin and ofloxacin were the best recommended drugs for empirical therapy for all organisms, the susceptibility rate being 80.7% and 80.4%.KEY WORDS: Antibiotic resistance, Soft tissue infections, Wound infections     

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.     

医院内感染调查及其病例分析

我院1986年8～10月院内感染率为9.06％,院内感染高危区为泌尿外科、血液病科、神经内科、神经外科、儿科。住院病人发生院内感染时的住院天数P_(95)=3.5天。院内感染病原体以绿脓杆菌多见,其耐药情况较社会感染病原体严重。住院病人抵抗力降低或具有感染倾向及各种诊疗操作手段等是院内感染的危险因素。     

55例金黄色葡萄球菌败血症临床分析

目的调查和分析金黄色葡萄球菌败血症的临床特点及耐药情况,为临床诊断和合理用药提供依据。方法采用血培养确诊为金黄色葡萄球菌败血症的55例患者,收集分析病史资料及相关实验室数据。结果55例患者中医院感染24例（43．6％）,社区感染31例（56．4％）,静脉药瘾者占社区感染9．7％。医院感染与社区感染患者临床症状、体征以及实验室检查结果无显著差异,发生迁徙性病灶者占65．5％,侵犯两个以上脏器占41．8％。医院感染患者多为合并基础疾病的老年人且具有多种易感因素,主要分布于ICU（37．4％）,病死率29．2％;社区感染患者则多为青壮年（80．6％）,主要分布于感染科（48．4％）,病死率3．2％。医院及社区感染金黄色葡萄球茵对青霉素耐药分别为100％和96．8％,医院感染株对苯唑西林耐药率明显高于社区感染株。结论金黄色葡萄球茵败血症临床表现多较严重,重者易合并多脏器损害。所有的金黄色葡萄球菌对多种临床常用抗菌药耐药率均有所升高,因此临床上疑有败血症病例应尽早做血、骨髓培养以及药敏试验,并合理应用药物治疗。     

Risk of death from methicillin-resistant Staphylococcus aureus bacteraemia: a meta-analysis

OBJECTIVE: To estimate the risk of death from healthcare-associated (nosocomial) bacteraemia caused by methicillin-resistant Staphylococcus aureus (MRSA), and compare it with that of nosocomial bacteraemia caused by methicillin-sensitive S. aureus (MSSA), by meta-analysis of selected studies. DATA SOURCES: Medline, EMBASE, Current Contents and Cochrane Library were searched for the period January 1978 (or earliest date of the database, if later than 1978) to December 2000. STUDY SELECTION: Studies which compared mortality of nosocomial MRSA and MSSA bacteraemia. DATA SYNTHESIS: Nine studies were analysed. All but one found an increased relative risk (RR) of death from MRSA bacteraemia, with RR ranging from 0.89 to 4.94. Meta-analysis showed that patients with MRSA bacteraemia have an RR of death, compared with patients with MSSA bacteraemia, of 2.12 (95% CI, 1.76-2.57) using the fixed-effect method, and 2.03 (95% CI, 1.55-2.65) using the random-effect method. CONCLUSION: MRSA bacteraemia is associated with a real increase in risk of death, further justifying ongoing MRSA surveillance and control in healthcare facilities.     

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.     

ICU中MRSA耐药基因检测及其PFGE分型

目的对耐甲氧西林金黄色葡萄球菌(MRSA)菌株进行分子分型,探讨ICU中MRSA医院感染的特点和流行规律。方法采用表型筛选和PCR扩增mecA基因方法鉴定MRSA菌株,脉冲场凝胶电泳方法(PFGE)进行分子分型。结果12株金黄色葡萄球菌表型筛选为MRSA,MRSA产生A型、B型、C型和D型4种耐药表型,优势耐药模式是A型(75.0%),MRSA对苯唑西林、阿莫西林/克拉维酸和氨苄西林/舒巴坦等10种抗生素产生100%耐药性,11株MRSA携带mecA基因,携带率为91.7%,PFGE指纹图谱分两型,分别为R1型和R2型,11株MRSA为R1型(91.7%),R1型各株间相似度为100%。结论ICU可存在MRSA爆发流行,MRSA产生多重耐药性(MDR),MRSA携带mecA基因可表现为MDR,PFGE分型是理想的分子流行病学溯源手段。     

Epidemiological and biological characteristics of methicillin-resistant staphylococcal infections in a Mexican hospital

BACKGROUND: Methicillin-resistant Staphylococcus aureus (MRSA) has spread worldwide since 1960. However, there is little information concerning methicillin-resistant coagulase-negative staphylococci (MRCNS) infections. METHODS: In order to study the clinical and epidemiological characteristics of methicillin-resistant staphylococci (MRS) infections and to determine the relationship between MRS and both synergistic hemolysis (SH) and slime production (SP), a laboratory-based survey and non-matched case-control study were carried out at a tertiary-care center in Mexico City. In regard to patients, from May 1991 to October 1992, 46 cases of MRS infection and 86 patients (controls) infected by methicillin-susceptible staphylococci (MSS) were included. Clinical and epidemiologic variables were analyzed. The isolates were identified and tested for antimicrobial susceptibility by standard methods. An MIC of oxacillin > or = 8 micrograms/mL was defined as an MRS. RESULTS: During the study, 94 nosocomial staphylococcal infections were diagnosed: S. aureus, 35 and CNS, 59; 43 (45.7%) by MRS (rate of MRS infections was 1.12 per 100 in-patients); 2 MRSA; 41 MRCNS, and only 19 were symptomatic. Three infections were community-acquired, including one MRSA and two MRCNS. After multivariate analysis, the significant risk factors were previous antimicrobial therapy (p = 0.013) and catheter-related (p = 0.009) and urinary-tract source (p = 0.0001). Forty-nine percent of MRS showed SH while only 15% of MSS (p < 0.001) showed SH, especially in 10/10 MR-S. hemolyticus. Additionally, 48% of MRCNS showed SP, as did 18% of MSCNS (p = 0.019), particularly in 15/20 MR-S. epidermidis. Of all MRS isolates, 38% showed a homogeneous phenotype, a trait associated with multi-drug resistance (p < 0.01) and SH (p < 0.001). CONCLUSIONS: CNS predominated as the cause of MRS infections in our setting. The homogenous phenotype was associated with SH and multi-drug resistance.     

无菌部位金黄色葡萄球菌耐药性及分子流行病学特征

目的:了解无菌部位分离的金黄色葡萄球菌对常用抗菌药物的耐药性及分子流行病学特征,为临床预防和控制其感染以及合理使用抗菌药物提供实验依据。方法:收集2011年8月至2012年6月某三甲医院无菌部位分离的非重复金黄色葡萄球菌50株。VITEK-2微生物分析系统进行菌株鉴定,PCR检测耐甲氧西林的金黄色葡萄球菌(MRSA)杀白细胞毒素(PVL)基因,多重PCR对MRSA进行SCCmec基因分型。结果:在18种抗菌药物中,青霉素和红霉素的耐药率最高,分别为90.0%和62.0%;尚无对万古霉素、替加环素、替考拉宁、利奈唑胺、达托霉素的耐药菌株。50株金葡菌中,MRSA 15株(30.0%),MSSA35株(70.0%),MRSA对12种抗菌药物的敏感率明显低于MSSA。15株MRSA中,SCCmecⅢ型11株(73.3%),SCCmecⅣ型4株(26.7%),PVL基因扩增均为阴性。结论:该院无菌部位分离的金黄色葡萄球菌以MSSA为主;MRSA对抗菌药物呈多重耐药性,且以SCCmecⅢ型为主。     

MRSA所致重症肺炎1例

目的:探讨耐甲氧西林金黄色葡萄球菌(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:分析该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:对于MRSA感染的肺炎患者,使用利奈唑胺能够有效抑制病原菌,并且不良反应少,治疗效果明显。结论:在治疗MRSA感染的社区获得性肺炎患者过程中,早期、正确使用抗生素能够提高患者治愈率。     

175 株金黄色葡萄球菌血流感染的临床分析

目的 研究金黄色葡萄球菌（SAU）的感染特点及耐药性,为合理控制SAU 血流感染提供依据。 方法 血培养、细菌鉴定和药物敏感分析采用血培养仪及全自动细菌鉴定及药物敏感分析系统。采用χ2 检 验耐甲氧西林金黄色葡萄球菌（MRSA）和甲氧西林敏感金黄色葡萄球菌（MSSA）对多种不同抗生素的耐 药率进行统计学分析。结果 175 例SAU 血流感染的患者中,因基础疾病引起者152 例,占86.9%,因肺部 感染引起者61 例,占34.9% ;SAU 对青霉素、阿奇霉素、红霉素、克拉霉素的耐药率均>90%,对利奈唑胺、 米诺环素和替考拉宁的耐药率均<10%,未发现耐万古霉素菌株。MRSA 对多种抗生素的耐药率大于MSSA。 结论 血流感染SAU 多继发于有严重基础疾病患者,其对多种抗生素的耐药率较高,但对利奈唑胺、米诺环素、 万古霉素仍保留较高敏感性。     

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.     

Nosocomial infections in an intensive care unit in a private hospital

The nosocomial infection rate in the intensive care unit (ICU) of a private hospital was assessed during an 18-month survey. From 629 admissions to the ICU, 139 hospital-acquired infections were identified. The rate was 22.1% compared to the overall nosocomial infection rate of 15.3% for the entire hospital. In the ICU, the main infections occurred in the respiratory tract, 41 (29.5%), followed by surgical wounds, 35 (25.2%), urinary tract, 28 (20.1%) and the blood stream, 24 (17.3%). From 165 bacterial isolates, 80% of isolates were gram-negative rods, with P aeruginosa, 48 (36.6%), being the predominant gram-negative isolate followed by Klebsiella pneumoniae, 27 (20.6%), and Enterobacter sp, 22 (16.8%). The main gram-positive isolates were S aureus, 23 (41.8%), coagulase-negative Staphylococci, 17 (30.9%), and Enterococci, 11 (20.0%). Of the 23 S aureus strains, 15 (65.2%) were methicillin-resistant (MRSA), (8 MRSA were from surgical wounds, 5 from the respiratory tract and 2 from infected urine). Only 2 of the 17 (11.8%) coagulase-negative staphylococci were methicillin-resistant, and both were isolated from wounds. Resistance to ampicillin and augmentin (amoxicillin-clavulanic acid) was high, 81.9% and 55.4%, respectively. Gentamicin, aztreonam, piperacillin and piperacillin-tazobactam showed resistance rates of less than 15%. Infection control measures aimed at reducing nosocomial infections at the hospital are often frustrated by apathy of hospital administrators who apparently are insensitive to the high nosocomial infection rate. Effort by the infection control team through seminars, lectures and newsletters have begun to show improvements in attitude and awareness of staff to infection control and preventative measures within the institution.     

金黄色葡萄球菌耐药性的研究

目的:监测金黄色葡萄球菌(SA)的耐药状况,为临床治疗SA感染提供依据。方法:对浙江省中医院2001年6月至2002年5月临床分离出的122例金黄色葡萄球菌进行药敏试验和临床资料分析。结果:临床分离的葡萄球菌在病区、标本分布方面以重症监护病房和痰标本多见。耐苯唑西林金黄色葡萄球菌(MRSA)占70.5％(86/122);苯唑西林敏感金黄色葡萄球菌(MSSA)占29.5％(36/122)。耐万古霉素金黄色葡萄球菌占3.3％(4/122)。结论:耐苯唑西林的金黄色葡萄球菌表现为多重耐药性,且对12种抗生素的耐药率明显高于苯唑西林敏感的葡萄球菌,P<0.01。发现4株耐万古霉素的金黄色葡萄球菌。     

The prevalence of nosocomial and community-acquired infections in Australian hospitals

The first national survey of the prevalence of nosocomial and community-acquired infections in Australian hospitals was carried out during July 1984. Data were collected on 28,643 patients in rural and metropolitan, public and private acute-care hospitals. The over-all adjusted prevalence of nosocomial infections was 6.3%; the prevalence of community-acquired infection was 9.7%. A total of 5940 infections occurred; 39% were hospital-acquired infections and 61% were community-acquired infections. These occurred at the following sites: the respiratory tract, 35.4% (2100 infections; contributing 19% of hospital-acquired infections and 46% of community-acquired infections); the urinary tract, 15.1% (896 infections; contributing 22% of hospital-acquired infections and 11% of community-acquired infections); surgical wounds, 13.4% (797 infections; contributing 34% of hospital-acquired infections); the gastrointestinal tract, 7.8% (466 infections; contributing 3.4% of hospital-acquired infections and 11% of community-acquired infections); skin, 6.3% (376 infections; contributing 4.4% of hospital-acquired infections and 8% of community-acquired infections); abscesses, 1.9% (113 infections; contributing 0.9% of hospital-acquired infections and 2% of community-acquired infections); traumatic wounds, 1.5% (90 infections; contributing 0.9% of hospital-acquired infections and 2% of community-acquired infections); bacteraemia, 1.5% (89 infections; contributing 1.6% of hospital-acquired infections and 1% of community-acquired infections); burns, 0.2% (14 infections; contributing 0.3% of hospital-acquired infections and 0.2% of community-acquired infections); and other, 16.8% (999 infections; contributing 13.4% of hospital-acquired infections and 19% of community-acquired infections). There was a significant association between hospital size and infection rates. The nosocomial infection prevalence rate increased from 4.2% in hospitals with 50-99 beds to 7.6% in hospitals with 500 or more beds. The prevalence of community-acquired infections was higher in rural (11.5%) than in metropolitan (8.7%) hospitals. After adjusting for hospital size, public hospitals had significantly-higher prevalences of nosocomial (6.7%) and community-acquired (10.6%) infection than did private hospitals (nosocomial infection, 4.8%; community-acquired infection, 6.3%).     

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.