Changes in susceptibilities to teicoplanin, vancomycin and other antibiotics among Staphylococcus aureus isolates in a tertiary-care University hospital

Changes in antibiotics susceptibilities were evaluated among 374 nosocomial clinical isolates of Staphylococcus aureus collected from 1986 to 1994 in a tertiary-care University hospital where methicillin-resistant S. aureus (MRSA) is an increasing cause of infection. Significant increases in resistance to ciprofloxacin, clindamycin and rifampicin were observed among MRSA isolates in recent years. No resistance to glycopeptides was observed. However, during the last 2 years a significant trend towards a decreasing susceptibility to teicoplanin was observed among MRSA isolates.     

An analysis of incidents of Staphylococcus in Kashima Rosai Hospital (I)

Isolation patterns and drug susceptibilities of Staphylococcus aureus and Staphylococcus epidermidis were investigated in Kashima Rosai Hospital, a local hospital with 300 beds opened in June, 1981. Our investigation covered 218 Staphylococcus strains isolated from various clinical materials in the Clinical Laboratory during a one year period in 1985. These isolated strains comprised of 8 species of genus Staphylococcus with S. aureus and S. epidermidis together accounted for 93.6% of all the clinically isolated Staphylococci. S. aureus was depicted in materials obtained from outpatients at a higher frequency than S. epidermidis, while the opposite was the case in materials obtained from inpatients. When distribution of these organisms were classified depending on clinical materials from which they were isolated, outpatient sources from which S. aureus were isolated at high frequencies were otorrhea and pus, while inpatient sources with high incidents of S. aureus isolation were sputum and pus. With regards to S. epidermidis, urine and pus from outpatients as well as from inpatients yielded this organism at high frequencies. Isolation frequency ratios in this hospital of methicillin-resistant S. aureus (MRSA) and S. epidermidis (MRSE) were 8.6% and 30.*%, respectively. These resistant strains were found from a large spectrum of clinical materials. Thus, these strains seemed to have established themselves more or less firmly among bacterial population in the hospital, hence alerting us the risk of hospital infections in compromised hosts. As to the coagulase typing of MRSA, type IV was the most frequent from outpatient sources whereas type II was the most frequent from inpatient sources including a large variety of clinical materials. The coagulase typing has been and rapid than the phage typing. We confirmed these in our investigation. Among beta-lactam antibiotics we tested against MRSA, flomoxef was found to be superior to the others. Cephalothin and cefamandole proved to be highly active against MRSE. Minocycline and vancomycin showed good activities against MRSE as well as MRSA.     

Antimicrobial therapy of Staphylococcus aureus bloodstream infection

Staphylococcus aureus bloodstream infection (BSI) contributes significantly to the morbidity and mortality of in-patients. The optimal therapy for methicillin-susceptible S. aureus BSI consists of penicillins. The efficacy of these drugs is well documented from several published data and supported from a long clinical experience. Methicillin-resistant S. aureus (MRSA) strains are responsible for the majority of nosocomial BSI and are recovered with increasing frequency at hospital admission. Although glycopeptides still represent the drugs of choice, there are several concerns on the treatment of MRSA BSI: reports of clinical failure with vancomycin treatment, regardless of the in vitro susceptibility; increasing reports of MRSA strains with reduced vancomycin susceptibility; difficulty in therapeutic dosage monitoring of teicoplanin; lack of evidence on the efficacy of combination therapy. Recently, new drugs have been introduced in the therapeutic arsenal for MRSA infections, but their clinical use is not yet clearly established for BSI. The review summarises evidence on present therapeutic options for the treatment of S. aureus BSI.     

2010—2012年我院临床细菌分布及耐药性分析

目的：了解2010—2012年我院常见病原菌分布特点及对各种临床常用抗菌药物的耐药性,为临床合理使用抗菌药物提供参考。方法：统计和整理2010—2012年我院送检细菌培养标本中分离出的病原菌,并对其耐药性进行分析。结果：2010—2012年我院共分离出病原菌5 992株,其中革兰阳性菌13 94株,占23.26%;革兰阴性菌4 691株,占78.29%。革兰阳性菌中,金黄色葡萄球菌中耐甲氧西林金黄色葡萄球菌（MRSA）菌株平均占68.37%,表皮葡萄球菌中耐甲氧西林表皮葡萄球菌（MRSE）菌株平均占69.51%。革兰阴性菌中,肠杆菌科细菌以大肠埃希菌最多见,非发酵菌科以铜绿假单胞菌多见。肠杆菌科细菌中产超广谱β-内酰胺酶（ESBL）大肠埃希菌的检出率为64.5%;产ESBL肺炎克雷伯菌的检出率为47.3%。结论：院内感染以革兰阴性杆菌为主,细菌耐药性呈增长趋势,需加强耐药性监测,尤其是对产酶菌和多重耐药菌的监测,应采取有效的控制措施,为临床正确使用抗菌药物提供参考。     

Multiple roles of Staphylococcus aureus enterotoxins: pathogenicity, superantigenic activity, and correlation to antibiotic resistance

Heat-stable enterotoxins are the most notable virulence factors associated with Staphylococcus aureus, a common pathogen associated with serious community and hospital acquired diseases. Staphylococcal enterotoxins (SEs) cause toxic shock-like syndromes and have been implicated in food poisoning. But SEs also act as superantigens that stimulate T-cell proliferation, and a high correlation between these activities has been detected. Most of the nosocomial S. aureus infections are caused by methicillin-resistant S. aureus (MRSA) strains, and those resistant to quinolones or multiresistant to other antibiotics are emerging, leaving a limited choice for their control. This review focuses on these diverse roles of SE, their possible correlations and the influence in disease progression and therapy.     

Linezolid - the first oxazolidinone in the treatment of nosocomial MRSA pneumonia

The incidence of nosocomial pneumonia involving multi-drug resistant Staphylococcus aureus strains (MRSA) in particular is on the rise worldwide. For years, vancomycin has been used as the drug of choice in the treatment of MRSA infections and was recommended as such by clinical guidelines. Inadequate drug levels in pulmonary compartments due to large molecular size may be the cause of the comparatively low survival rates of patients with MRSA pneumonia treated with vancomycin, despite in vitro susceptibility of the bacterial isolates. Several trials demonstrated the clinical effectiveness of the novel oxazolidinone linezolid in nosocomial MRSA pneumonia. Linezolid achieves higher pulmonary concentrations than vancomycin which may be the cause of superior survival rates observed with linezolid in nosocomial MRSA pneumonia. Staphylococcus aureus strains with reduced susceptibility to vancomycin (VISA) are encountered with increasing frequency and may contribute to clinical failures of vancomycin. To date, linezolid-resistance appears to be rare and predominantly affects Enterococci, while very few linezolid-resistant S. aureus isolates were reported. Reduced susceptibility to linezolid is caused by point mutations in the 23S ribosomal RNA genes, which may be selected for by long-term therapy. The future development of linezolid resistance is hard to predict since the drug has been in use only for a limited period of time. This article describes the drug profile, patents and current data on the clinical efficacy of linezolid and reviews its role in treatment of MRSA pneumonia.     

MRSA--what is it, and how do we deal with the problem?

Methicillin-resistant Staphylococcus aureus (MRSA) has become a serious nosocomial pathogen, and more recent reports in the scientific literature underscore the potential issues with emerging community-MRSA. MRSA is reported to be involved in > 50% of hospital S. aureus infections, more in the intensive care unit (ICU) than the non-ICU, and increases in multi-drug resistant MRSA and increasingly virulent MRSA have been reported. Together with its broad-based beta-lactam resistance, MRSA often possesses a multi-drug resistance genotype, including cephalosporins, aminoglycosides, fluoroquinolones, and macrolide resistances. MRSA has now emerged as the predominant nosocomial Gram-positive pathogen, and it has a high rate of morbidity and mortality. Action must be taken to contain and eradicate MRSA through a combination of infection control, the development of novel anti-MRSA agents, development of vaccines and other non-traditional approaches of intervention.     

41株金黄色葡萄球菌耐药性分析及PVL基因检测

目的了解临床分离金葡菌对常用抗生素的耐药性和杀白细胞毒素(PVL)基因携带情况。方法采用头孢西丁纸片扩散法检测耐甲氧西林金黄色葡萄球菌(MRSA),K-B法检测临床分离的41株金葡菌对常用抗生素的敏感性,PCR法检测mecA基因和PVL基因携带情况。结果 41株金葡菌中MRSA占51.2%,MRSA对克林霉素、红霉素、氨基糖苷类和喹诺酮类耐药率明显高于甲氧西林敏感金黄色葡萄球菌(MSSA),MRSA和MSSA对复方新诺明敏感率分别为90.5%和95%,未发现对万古霉素、替考拉林和利奈唑胺耐药株。21株MRSA mecA基因均阳性,41株金葡菌中共检出2株携带PVL基因,MRSA与MSSA各占1株,均分离自骨科病房。结论该院临床分离MRSA耐药率高,应规范临床用药,加强MRSA耐药性监测,加强PVL基因的检测,防止此类菌株的播散。     

某院新生儿科6 年间金黄色葡萄球菌临床分离株的分布及耐药情况

目的 了解该院新生儿科2012-2017 年间分离出金黄色葡萄球菌(SA) 临床分布情况及耐药性分析，为临床经验治 疗SA 相关感染和新生儿院内感染控制提供科学依据。方法 回顾性分析2012 年1 月-2017 年12 月宜宾市第一人民医院新生 儿科住院患者分离的SA 的标本分布并采用WHONET 5.6 软件进行耐药性分析。结果 6 年间该科共送检细菌培养标本25543 份， 共分离出不重复SA 509 株检出率为1.99%。SA 标本来源首位是呼吸道标本占86.25%，其次为脓液占5.11%，全血与分泌物标本 各占3.54%；509 株SA 中甲氧西林敏感的金黄色葡萄球菌(MSSA)407 株(79.96%)，检出耐甲氧西林金黄色葡萄球菌(MRSA)102 株，MRSA 检出率为0.4%，占比为20.04%；MSSA 除对庆大霉素耐药性高于MRSA 外，其余抗生素耐药性均较MRSA 低，差 异具有统计学意义(P<0.05)。MRSA 对红霉素、克林霉素耐药率分别为77.5% 和62.7%，对四环素耐药率为45.1%，对复方磺胺 甲噁唑耐药率为20.6%，对喹诺酮类、氨基糖苷类、利福平的耐药率均在10% 以下。未发现万古霉素、利奈唑胺非敏感菌株。 结论 该院新生儿SA 感染以呼吸道感染为主，新生儿MRSA 的检出率及占比与国内已有报道存在较大差异，这可能与年龄段 及地区差异有关。由于新生儿感染SA 尤其MRSA 感染的经验治疗可选抗菌药物非常有限。因此，一旦发生疑似感染应参考本 院耐药检测数据及有关诊疗指南积极治疗并进一步采取有效感控措施，减少SA 尤其是MRSA 传播感染。     

临床标本耐甲氧西林金黄色葡萄球菌分布及药敏分析

目的：了解医院内感染耐甲氧西林金黄色葡萄球菌（MRSA）的耐药情况,指导临床合理使用抗菌药物。方法：将本院2008年1月～2010年11月送检的标本进行回顾性分析。结果：共检出金黄色葡萄球菌380株,MRSA检出率为61.8%（235/380）。MRSA对常用抗菌药物有较高的耐药率,其中,青霉素、庆大霉素、红霉素、诺氟沙星、左氧氟沙星耐药率较高,为62%～99%,万古霉素、替考拉宁的敏感性为100.0%。结论：医院内耐甲氧西林金黄色葡萄球菌耐药率高,应加强耐药监测,合理使用抗菌药物。     

Antibiotic resistance in staphylococci

When penicillin was introduced in 1944 over 94% of Staphylococcus aureus isolates were susceptible; by 1950 half were resistant. By 1960 many hospitals had outbreaks of virulent multi-resistant S. aureus. These were overcome with penicillinase-stable penicillins, but victory was brief; methicillin-resistant S. aureus (MRSA) were recorded in the year of the drug's launch. MRSA owe their behaviour to an additional, penicillin-resistant peptidoglycan transpeptidase, PBP-2', encoded by mecA. Their spread is clonal, with transfer of mecA being extremely rare. MRSA accumulated and then declined in the 1960s and 1970s, but became re-established in the early 1980s. Some early MRSA strains were colonists rather than invaders and the proportion of MRSA among S. aureus bacteraemias in England remained under 3% until 1992. However, this proportion rose to 34-37% by 1998-1999, reflecting the dissemination of two new epidemic strains, EMRSA 15 and 16. These may be more virulent than earlier MRSA, or their success may reflect changing hospital practice. Until 1996, glycopeptides were universally active against S. aureus; then glycopeptide-intermediate S. aureus (GISA) were found in Japan, France, and the USA. This resistance is associated with increased wall synthesis. Coagulase-negative staphylococci (CNS) are less pathogenic than S. aureus but are important in line-associated bacteraemias and prosthetic device infections. They are even more often resistant than S. aureus, notably to teicoplanin. Few anti-staphylococcal agents were launched from 1970 to 1995, but the situation is now improving. Dalfopristin/quinupristin inhibits virtually all S. aureus, although its bactericidal activity is impaired against strains with constitutive MLSB-type resistance; other new agents are in advanced development. New agents give a renewed opportunity for control, but S. aureus is a resilient foe, able to regain its importance if drugs are used profligately or if hygiene is slackened.     

MRSA: status and prospects for therapy? An evaluation of key papers on the topic of MRSA and antibiotic resistance

Methicillin-resistant Staphylococcus aureus (MRSA) is a serious nosocomial pathogen, and a related community-sourced MRSA is emerging. MRSA has evolved to become the major S. aureus phenotype in the hospital, emerging from just 30 to over 60% of the S. aureus population over the past 15 years. Together with its β-lactam resistance, MRSA possesses multi-drug resistance genotype, including quinolones, macrolides and sulfonamides. MRSA has now emerged as the predominant nosocomial Gram-positive pathogen, and it has a high rate of mortality. Action must be taken to contain and eradicate MRSA through a combination of infection control and the development of novel anti-MRSA agents and vaccines.     

MRSA: status and prospects for therapy? An evaluation of key papers on the topic of MRSA and antibiotic resistance

Methicillin-resistant Staphylococcus aureus (MRSA) is a serious nosocomial pathogen, and a related community-sourced MRSA is emerging. MRSA has evolved to become the major S. aureus phenotype in the hospital, emerging from just 30 to over 60% of the S. aureus population over the past 15 years. Together with its beta-lactam resistance, MRSA possesses multi-drug resistance genotype, including quinolones, macrolides and sulfonamides. MRSA has now emerged as the predominant nosocomial Gram-positive pathogen, and it has a high rate of mortality. Action must be taken to contain and eradicate MRSA through a combination of infection control and the development of novel anti-MRSA agents and vaccines.     

Changes in the epidemiology of methicillin-resistant Staphylococcus aureus in a Greek tertiary care hospital,over an 8-year-period

A total of 1019 non-replicate, consecutively isolated methicillin-resistant Staphylococcus aureus (MRSA) strains were collected from in-patients of a tertiary care general hospital in Athens, Greece, during the period 1994–2001. The susceptibility, resistance phenotypes and the dissemination of these isolates among hospital wards were studied. Total MRSA and gentamicin-resistant MRSA, as a proportion of the S. aureus isolates, increased from 33 and 9% in 1994 to 50.1 and 33.3% in 2001, respectively. Three main multi-resistant phenotypes predominated, representing 50.9% of the total MRSA isolates in 2001. MRSA strains susceptible to all antibiotics tested decreased to 1.9% in 1997 and again increased to 13.5% in 2001. A gradual decrease in the susceptibility of vancomycin during the 8-year-period was detected, but no vancomycin resistant S. aureus strains were isolated.     

金黄色葡萄球菌感染的临床分析

目的探讨金黄色葡萄球菌所致感染的临床特点及耐药情况,为临床治疗金黄色葡萄球菌感染提供指导。方法收集确诊为金黄色葡萄球菌感染病例的临床资料,分析临床特点,对分离到的菌株进行药物敏感性测定。结果共66例金黄色葡萄球菌感染患者,感染部位以肺部最多见,共分离出68株金黄色葡萄球菌,包括其中耐甲氧西林金黄色葡萄球菌(MRSA)20株,占29.85%;甲氧西林敏感金黄色葡萄球菌(MSSA)56株,占69.14%。金黄色葡萄球菌对多种抗菌药物呈普遍耐药,未发现耐万古霉素MRSA菌株。结论金黄色葡萄球菌感染以肺部感染最多见,MRSA表现为多药高度耐药,但糖肽类药物敏感性高。     

对108株金黄色葡萄球菌的耐药性分析

目的了解我院金黄色葡萄球菌临床分离株对抗菌药物的耐药性及感染现状,以指导临床医生更科学合理用药。方法收集我院2009年11月-2011年9月间住院及门诊患者的标本,对分离出的108株金黄色葡萄球菌进行药敏试验。结果对甲氧西林耐药的金黄色葡萄球菌（MRSA）有76株,占70．4％;对甲氧西林敏感的金黄色葡萄球菌（MSSA）有32株,占29．6％。菌株主要分离于痰液／咽拭子,占42．6％;其次是分离于脓液／创面,占36．1％;其他的菌株分离于阴道分泌物、血液、尿液和精液,占21．3％。金黄色葡萄球菌中MRSA对16种抗菌药物的耐药率最高的是青霉素和苯唑西林,均为100．0％,而MSSA仅对青霉素的耐药率较高,达83．2％,对其余15种药物的耐药率都低于50％。万古霉素、呋喃妥因、替考拉宁耐药率在两者均为0。结论甲氧西林敏感金黄色葡萄球菌除了青霉素外对大多数的抗菌药物有较好的敏感性,而耐甲氧西林金黄色葡萄球菌的检出率仍然很高且多为多药耐药性。     

获得性感染金黄色葡萄球菌耐药的现状及治疗对策

目的：分析医院与社区获得性感染金黄色葡萄球菌（SAU）耐药现状,给临床合理用药提供参考。方法：收集2005年～2007年临床分离的金黄色葡萄球菌,培养鉴定,采用纸片扩散法（K—B法）测定16种抗菌药物的敏感情况。用WHONET5软件进行分析。结果：440株金黄色葡萄球菌,其中耐甲氧西林金黄色葡萄球菌（MRSA）为260株,占59．1％：甲氧西林敏感金黄色葡萄球菌（MSSA）为180株,占40．9％;SAU对16种抗菌药物的耐药率最高的是青霉素G为85．5％、万古霉素耐药率为0。结论：MSSA对大部分抗菌药物仍保持较好的敏感性。而MRSA表现为多重耐药性．但万古霉素例外。所以对耐万古霉素金黄色葡萄球菌（VISA及VRSA）的连续监测、了解葡萄球菌属的耐药机制具有重要的临床意义。     

Nosocomial infections due to methicillin-resistant Staphylococcus aureus and vancomycin-resistant enterococci at a university hospital in Taiwan from 1991 to 2003: resistance trends, antibiotic usage and in vitro activities of newer antimicrobial agents

A rapid increase of nosocomial methicillin-resistant Staphylococcus aureus (MRSA) infection (from 39% in 1991 to 75% in 2003) and vancomycin-resistant enterococci (VRE) (from 1.2% in 1996 to 6.1% in 2003) at a university hospital in Taiwan was found. The noticeable rise of MRSA and VRE was significantly correlated with the increased consumption of glycopeptides, beta-lactam-beta-lactamase inhibitor combinations, extended-spectrum cephalosporins, carbapenems and fluoroquinolones (Pearson's correlation coefficient, P < 0.05). Minimum inhibitory concentrations (MICs) of 100 non-duplicate blood isolates of MRSA (in 2003) and of 25 non-duplicate isolates of vancomycin-resistant Enterococcus faecalis and 172 vancomycin-resistant Enterococcus faecium (in 1996-2003) causing nosocomial infection recovered from various clinical specimens of patients treated at the hospital to nine antimicrobial agents were determined by the agar dilution method. All of these isolates were susceptible to linezolid and were inhibited by 0.5mg/L of tigecycline, and all MRSA isolates were inhibited by daptomycin 1mg/L, including two isolates of MRSA with heteroresistance to vancomycin. Daptomycin had two-fold better activity against vancomycin-resistant E. faecalis (MIC90, 2 mg/L) than against vancomycin-resistant E. faecium (MIC90, 4 mg/L). Decreased susceptibilities of vancomycin-resistant E. faecium and MRSA to quinupristin/dalfopristin (non-susceptibility 25% and 8%, respectively) were found. Telithromycin had poor activity against the isolates tested (MIC90, 8 mg/L). Linezolid, daptomycin and tigecycline may represent therapeutic options for infections caused by these resistant Gram-positive organisms.     

Susceptibilities of bacteria isolated from patients with lower respiratory infectious diseases to antibiotics (1998)

The bacteria isolated from the patients with lower respiratory tract infections were collected by institutions located throughout Japan, since 1981. Ikemoto et al. have been investigating susceptibilities of these isolates to various antibacterial agents and antibiotics, and analyzed some characteristics of the patients and isolates from them each year. Results obtained from these investigations are discussed. In these 18 institutions around the entire Japan, 532 strains of presumably etiological bacteria were isolated mainly from the sputa of 438 patients with lower respiratory tract infections during the period from October in 1998 to September in 1999. MICs of various antibacterial agents and antibiotics were determined against 85 strains of Staphylococcus aureus, 100 strains of Streptococcus pneumoniae, 96 strains of Haemophilus influenzae, 75 strains of Pseudomonas aeruginosa (non-mucoid strains), 6 strains of Pseudomonas aeruginosa (mucoid strains), 38 strains of Moraxella subgenus Branhamella catarrhalis, 26 strains of Klebsiella pneumoniae etc., and the susceptibilities of 517 strains were assessed except for those strains that died during transportation. S. aureus strains for which MICs of oxacillin (MPIPC) were higher than 4 micrograms/ml (methicillin-resistant S. aureus: MRSA) accounted for 60.0%. Vancomycin (VCM) and arbekacin (ABK) showed the most potent activities against MRSA. But one of MRSA showed resistance to ABK with the MIC of 64 micrograms/ml. The sensitive strains of MRSA to VCM have decreased. The frequency of penicillin (PC)-intermediate S. pneumoniae (PISP) + PC-resistant S. pneumoniae (PRSP) have increased in 46.0% for 1998 comparatively from 30.9% of 1997's. But PRSP decreased, and PISP increased into 39.0% of 1998 years from 19.8% of 1997's. Panipenem (PAPM), imipenem (IPM) and faropenem (FRPM) showed the most potent activities against S. pneumoniae with MIC80s of 0.125 microgram/ml or below. Against H. influenzae and M. (B.) catarrhalis, almost all the drugs showed good activities. The sensitive strains of them against ceftazidime (CAZ) decreased in 1997, but those have increased in 1998. Inversely, the susceptibility of them against cefotiam (CTM) had been higher in 1997, but those have been lower in 1998. Tobramycin (TOB) showed the most potent activity against P. aeruginosa (both mucoid and nonmucoid strains). All drugs except ampicillin (ABPC) were active against K. pneumoniae. A quite few of K. pneumoniae showed low susceptibilities. Also, we investigated year to year changes in the characteristics of patients, their respiratory infectious diseases, and the etiology. The examination of age distribution indicated that the proportion of patients with ages over 70 years was 48.6% of all the patients showing a slight increase in every year. About the proportion of diagnosed diseases as follows: Bacterial pneumonia was the most frequent with 40.2%. The ratio of it has increased slightly, and the increased rate was 10% in patients with ages over 70 years compared with the results in 1997. Chronic bronchitis have decreased slightly with 27.6% in 1998. Number of strains isolated from patients before administration of antibiotics were more than those after administration of them in chronic bronchitis, but these were almost same number in bacterial pneumonia. Administration of antibiotics has changed the results of the frequency of isolation of bacterial species. Bacterial isolations before administration of antibiotics were as follows: S. pneumoniae 26.7%, H. influenzae 23.8%, S. aureus 13.3% and M. (B.) catarrhalis 10.8%. The frequencies of S. aureus decreased after antibiotics administration over 15 days, but the frequencies of P. aeruginosa (both mucoid and non-mucoid) was not affected. The frequencies of P. aeruginosa was 45.5% after administration over 15 days. The frequencies of S. pneumoniae decreased upon administration of antibiotics, these were only 4.5% over 15 days. The frequencies of H. (     

The incidence of methicillin resistant S. aureus strains in clinical specimens in relation to their beta-lactamase producing and multiple-drug resistance properties in Addis Abeba

From December 1987 to July 1988, a total of 17,142 clinical specimens were examined at the National Research Institute of Health (NRIH), Addis Abeba, to determine the incidence of methicillin resistant S. aureus (MRSA) strains. Coagulase positive Staphylococcus spp. were isolated from 355 specimens. Two hundred and forty-nine 249 (70%) isolates were tested for methicillin resistance by minimum inhibition concentration method (MIC) of which 76 (30.5%) were found to be MRSA and 173 (69.5%) were methicillin sensitive S. aureus (MSSA) strains. The presence of beta-lactamase production was determined in the 355 S. aureus isolates using the rapid Iodometric and Nitrocefin methods and 252 (71%) isolates were found to be beta-lactamase procedures. Furthermore, 47 (62%) of the 76 MRSA isolates and 140 (81%) of the 173 MSSA isolates were beta-lactamase positive strains. The sensitivity pattern of all the S. aureus isolates against 11 common drugs indicated that the majority (80%) of the MRSA strains were multipledrug resistant while 4 (8%) were not resistant to any of the drugs tested. Among the antibiotics, vancomysin and clindamycin were effective against all S. aureus isolates. It was also found that 41 (54%) of the MRSA strains were both betalactamase producers and multiple-drug resistant isolates; of the latter, 36 (87.8%), strains were isolated from pus specimens of patients with post-operative wound infections. The results of this study show that MRSA strains are quite prevalent among specimens referred to the NRIH.