体外诱导万古霉素耐药金葡菌及耐药菌株抗生素敏感性变化分析

目的诱导对万古霉素耐药金葡菌,分析金葡菌对万古霉素耐药后其他的药物敏感性变化情况。方法在体外用万古霉素对15株金葡菌进行诱导;诱导过程中检测23SrRNA基因对菌种进行鉴定;诱导出万古霉素耐药金葡菌后,检测耐药菌株其他抗生素药物敏感性并与诱导前进行比较。结果诱导出3株对万古霉素中介耐药金葡菌;诱导前后菌株都扩增出金葡菌23SrRNA基因;对万古霉素耐药后金葡菌对其他抗生素药物敏感性也发生改变。结论万古霉素体外很难诱导完全耐药菌株,但可以诱导出中介耐药菌株;对万古霉素耐药后金葡菌对其他抗生素耐药性也增加。     

Seeking vancomycin resistant Staphylococcus aureus among patients with vancomycin-resistant enterococci.

Clinical isolates of Staphylococcus aureus displaying intermediate resistance to vancomycin (VISA) have been identified. The objective of our study was to identify VISA colonization among patients known to be colonized or infected with vancomycin-resistant enterococci (VRE). Eight weekly point prevalence screening surveys for VRE and S. aureus were conducted on 5 hospital units. Of the 243 patients screened, 31 (12.8%) were colonized with VRE. In addition, 18 inpatients were already known to be VRE-positive. Fourteen (28.6%) of the 49 VRE-positive patients were co-colonized with S. aureus. All 30 S. aureus isolates from these 14 patients were methicillin-resistant (MRSA) but remained vancomycin-susceptible (minimal inhibitory concentration [MIC] range, 0.75-2 microg/mL). Population analysis profiling demonstrated no evidence of heteroresistant subpopulations that could grow on agar containing 3 microg/mL vancomycin for any of the MRSA isolates. Although 23 (77%) of 30 staphylococcal isolates had vancomycin MICs of 1.5 or 2 microg/mL, no VISA strains (MICs, 8-16 microg/mL) were recovered.     

Epidemiological investigation of "beta-lactam antibiotic induced vancomycin-resistant MRSA (BIVR)"

Mu3 strain with heterogeneous intermediated-resistance to vancomycin (hetero-VISA) reported in 1997, also have possessed a character of an antagonistic effect of beta-lactam antibiotics and vancomycin. Mu3 is only strain which satisfies the definition of hetero-VISA in Japan. But, MRSA with antagonistic effects of beta-lactam antibiotics and vancomycin, was reported by many institutions. To separate hetero-VISA, we called "beta-lactam antibiotic induced vancomycin-resistant MRSA (BIVR)". But the detection rate of clinical isolated BIVR in Japan is unknown, we reported on the detection method and the epidemiological investigation for BIVR. Mu 3 agar containing 4 micrograms/mL of vancomycin is used to detect BIVR. Mu3 strains were spread on the agar, BIVR can grow around the paper disc impregnated with ceftizoxime or grow on the whole surface on Mu 3 agar after incubation. The detection rate of BIVR was 45 in 717 (6.3%) clinical isolated strains. In detected strains as BIVR, the number of strains with grown on the whole surface of Mu3 agar showing a high resistance to vancomycin were 10 strains (1.4%). Besides, from 106 strains of blood isolates MRSA, BIVR were detected 16 strains (15.1%), from 611 strains of non-blood isolates MRSA, BIVR were detected 29 strains (4.7%) (P < 0.0001). In BIVR strains grown on the whole surface of Mu3 agar, the number of BIVR strains isolated from blood were 8 in 106 (7.5%), from non-blood were 2 in 611 (0.3%) (P < 0.0001). On one side, hetero-VISA were not detected from all of BIVR growing on the whole surface of Mu3 agar. As a result, detection method and the definition of BIVR were quite different from those of hetero-VISA. An existence of BIVR in Japan was confirmed, we thought that the high detection rate of BIVR isolated from blood compared with that of non-blood showed the pathogenecity of BIVR which contribute to MRSA infections.     

Vancomycin-resistant Staphylococcus aureus: a new model of antibiotic resistance

Vancomycin has been the most reliable therapeutic agent against infections caused by meticillin-resistant Staphylococcus aureus (MRSA). However, in 1996 the first MRSA to acquire resistance to vancomycin, was isolated from a Japanese patient. The patient had contracted a post-operative wound infection that was refractory to long-term vancomycin therapy. Subsequent isolation of several vancomycin resistant S. aureus (VRSA) strains from USA, France, Korea, South Africa, and Brazil has confirmed that emergence of vancomycin resistance in S aureus is a global issue. A certain group of S. aureus, designated hetero-VRSA, frequently generate VRSA upon exposure to vancomycin, and are associated with infections that are potentially refractory to vancomycin therapy. Presence of hetero-VRSA may be an important indicator of the insidious decline of the clinical effectiveness of vancomycin in the hospitals. Vancomycin resistance is acquired by mutation and thickening of cell wall due to accumulation of excess amounts of peptidoglycan. This seems to be a common resistance mechanism for all VRSA strains isolated in the world so far.     

Selection for vancomycin resistance in clinical isolates of Staphylococcus haemolyticus

Killing curves were used to characterize Staphylococcus haemolyticus isolates previously reported to contain subpopulations showing increased resistance to vancomycin. Results suggested that vancomycin and teicoplanin were ineffective at a concentration of 8 micrograms/ml and growth was seen between 24 and 48 h. Conversely, the lipopeptide antibiotic daptomycin at the same concentration rapidly killed tested strains by 6 h. Various staphylococcal strains were examined to determine if vancomycin resistance could be selected in all strains of staphylococci, was specie(s) restricted, or was unique to this patient's clinical isolates. About 1 x 10(8) colony-forming units were added to melted brain-heart infusion agar plates containing 12 micrograms/ml of vancomycin. Plates were examined after 48 h for presence of resistant clones. Results indicated that selection for vancomycin resistance was restricted to S. haemolyticus strains. Further, all S. haemolyticus isolates that displayed a double zone of growth around imipenem agar diffusion discs (Impdz) contained stably resistant subpopulations. Vancomycin resistance could not be selected in imipenem-sensitive derivative clones. Impdz isolates that were recovered from geographically distinct locations displayed nearly identical SDS-PAGE protein profiles. It appears that a characteristic susceptibility pattern displayed by clinical isolates of S. haemolyticus may provide a marker for those strains that contain subpopulations having increased resistance to vancomycin.     

新疆某医院多重耐药菌及耐药性分析

目的回顾性分析2015年新疆医院临床分离多重耐药菌(multidrug-resistant organism,MDRO)的分布、类型及耐药性,为临床控制MDRO医院感染提供有效依据,为临床合理选用抗生素提供参考依据。方法 2015年1月至2015年11月期间对我院住院患者标本培养的多重耐药菌株,对其耐药菌类型与耐药性进行分析,并对高危因素进行分析与探讨。结果共检出、共分离出4560株细菌,其中多重耐药菌1210株。鲍曼不动杆菌344株,占28.40%,大肠埃希菌288株,占23.80%,铜绿假单胞菌201株,占16.60%,肺炎克雷伯菌150株,占12.40%,金黄色葡萄球菌100株,占8.30%,耐药性:鲍曼不动杆菌对碳青霉烯类抗生素耐药性为62.30%,多耐药肠杆菌科细菌对碳青霉烯类抗生素保持高度的敏感性(100%敏感),革兰氏阳性细菌主要为金黄色葡萄球菌,耐甲氧西林的金黄色葡萄球菌(MRSA)占65%,只对万古霉素敏感,未发现耐万古霉素、耐利奈唑胺菌株。结论该院分离的多重耐药菌种类多,耐药性严重,临床医师应重视病原学检查,并严格按照药物敏感试验结果选取合理抗生素,以减少细菌耐药性的发生,降低医疗费用,降低临床病死率。     

Susceptibility to vancomycin of methicillin-resistant Staphylococcus aureus isolated in a university hospital in Japan

Intravenous vancomycin was approved in 1991 in Japan and has been widely used for treatment of infections caused by methicillin-resistant Staphylococcus aureus (MRSA). Consequently, ever since the initial discovery of vancomycin intermediate-resistant S. aureus in Japan, the vancomycin resistance of this organism has been a great concern in clinical settings. We investigated whether vancomycin resistance had emerged in MRSA isolated in our hospital since the approval of the use of intravenous vancomycin. Vancomycin susceptibility was evaluated on the basis of minimum inhibitory concentrations determined by the agar dilution method and a heterogeneous resistance examination. The median minimum inhibitory concentration of the 69 MRSA strains isolated in 1988 and the 74 isolated in 1998 was 0.75 microgram/ml and 1.0 microgram/ml, respectively (p < 0.001), however, all of the strains were classified in the susceptible group. None of them was an MRSA heterogeneously resistant to vancomycin (hetero-VRSA), which has been defined as a strain having a 1/10(6) or greater heterogeneously resistant subpopulation to vancomycin. In another set of investigations, no hetero-VRSA were found among 12 other MRSA strains isolated after intravenous administration of vancomycin for 14 or more days (range: 14 to 77 days). We conclude that while the use of intravenous vancomycin may have slightly lowered the vancomycin susceptibility of MRSA in our hospital, the decrease in so small that it may not be significant clinically. In addition, no hetero-VRSA were found in our hospial.     

Epidemiology and mechanisms of glycopeptide resistance in enterococci

PURPOSE OF REVIEW: This review updates epidemiologic trends and our understanding of glycopeptide resistance in enterococci. RECENT FINDINGS: Colonization and infection rates with vancomycin resistant enterococci continue to increase throughout the world while factors contributing to this rise continue to be defined. While no interventions exist to eradicate colonization, infection control procedures are cost effective and decrease the prevalence of vancomycin resistant enterococcal colonization and infection. New molecular methods show great promise in strengthening our ability to detect colonization with these bacteria. Furthermore, our understanding of the origin of vancomycin resistant enterococci continues to grow. Paenibacillus species found in soil have been found to carry homologues of vanA-associated glycopeptide resistance genes found in enterococci. Also, additional evidence supports previous data that VanB-associated resistance may have been horizontally transferred from gastrointestinal tract bacteria to enterococci. Finally, glycopeptide resistance has been transferred to methicillin-resistant Staphylococcus aureus in clinical practice on several occasions. SUMMARY: The prevalence of vancomycin resistant enterococci will likely continue to increase. Implementation of infection control strategies, in conjunction with deployment of advanced technologies for detection of vancomycin resistant enterococci, may curb this rise. The emergence of vancomycin resistant S. aureus is of concern.     

Prevention of MRSA pneumonia by oral vancomycin decontamination: a randomised trial.

This study was undertaken to assess whether oropharyngeal vancomycin may control oropharyngeal carriage and lower airway infection due to methicillin-resistant Staphylococcus aureus (MRSA) acquired in the intensive care unit (ICU). Secondary endpoints were the emergence of vancomycin-resistant enterococci, vancomycin-intermediate S. aureus and vancomycin consumption. A total of 84 patients, admitted to a medical/surgical ICU and mechanically ventilated for >72 h, were randomly assigned to control (n=42) or test (n=42) group. Both groups received the protocol of selective decontamination of the digestive tract, including polymyxin E, tobramycin and amphotericin B. Patients in the test group received 0.5 g of a 4% vancomycin gel at 6-h intervals in the oropharynx. Lower airway infections due to MRSA acquired on the ICU were reduced in the test group, as was oropharyngeal carriage. Neither vancomycin-resistant enterococci nor vancomycin-intermediate S. aureus were isolated from either surveillance or diagnostic samples during the study period. The vancomycin costs were lower in the test group. This study demonstrates that oropharyngeal vancomycin, which controls intensive care unit-acquired lower airway infections and secondary carriage due to methicillin-resistant Staphylococcus aureus, is cost-effective and safe in terms of vancomycin-resistant enterococci and vancomycin-intermediate Staphylococcus aureus.     

2004-2005年度全国革兰阳性菌耐药监测(Mohnarin)

目的 监测2004-2005年度全国临床分离革兰阳性菌耐药状况.方法 选定全国17家医院作为成员单位,收集特定病房2004年10月1日至2005年9月30日分离的革兰阳性致病菌,用标准平皿二倍稀释法测定35种药物体外抗菌活性,计算最低抑菌浓度(MIC)50、MIC90,依据2004年美国国家临床实验标准委员会制订的标准计算细菌对抗菌药物的耐药率、中介率和敏感率.结果 共收集革兰阳性菌925株,包括葡萄球菌536株、肠球菌249株、链球菌137株和其他革兰阳性菌3株.苯唑西林耐药金黄色葡萄球菌与苯唑西林耐药表皮葡萄球菌的检出率分别为62.9%和82.9%;肺炎链球菌对青霉素的耐药率为10.5%,中介率为30.2%,不敏感率合计为40.7%;未发现对替考拉宁中介或耐药的肠球菌,5株肠球菌对万古霉素中介,分别为1株粪肠球菌、2株屎肠球菌、1株鹑鸡肠球菌和1株鸟肠球菌;术发现糖肽类不敏感葡萄球菌.结论 革兰阳性菌耐药呈明显上升趋势,青霉素不敏感肺炎链球菌、甲氧西林耐药的葡萄球菌比例高;细菌对大环内酯类耐药率高;未发现对万占霉素耐药的革兰阳性细菌.     

Investigation of infective endocarditis clinical isolates of methicillin resistant Staphylococcus aureus non-responsive to vancomycin

Methicillin resistant Staphylococcus aureus (MRSA) is one of the most important strains which induce hospital and post-operative infection. In cases of infective endocarditis in which VCM was not efficacious, MRSA strains were chronologically isolated at three different times and examined with the following parameters: minimum inhibitory concentration (MIC), fractional inhibitory concentration (FIC) index, Mu 3 agar, population analysis, pulse field gel electropholesis (PFGE). The PFGE banding patterns of the three MRSA isolates were the same, therefore, it was concluded that the same strain of MRSA was selected for reduced susceptibility. A pattern of Mu 3 and Mu 50 was demonstrated under population analysis.     

对老年住院患者连续三年分离致病菌耐药性监测的分析

目的 了解2006-2008年我院老年患者分离菌株对常用抗菌药物的耐药性.方法 采用纸片扩散法,对老年患者分离菌5710株进行药物敏感性试验,WHONET5.4统计软件对数据进行分析.结果 分离革兰阴性杆菌前3位分别为铜绿假单胞菌、大肠埃希菌和嗜麦芽窄食单胞菌;革兰阳性球菌前4位分别为金黄色葡萄球菌、凝固酶阴性葡萄球菌、肺炎链球菌及肠球菌属.体外药物敏感性试验结果显示.121株肺炎链球菌中,19株为青霉素不敏感株,占15.7%;690株金黄色葡萄球菌中.对甲氧西林耐药的金黄色葡萄球菌占80.2%;未发现对万古霉素不敏感的葡萄球菌.分离到114株粪肠球菌和95株屎肠球菌,屎肠球菌的耐药性高于粪肠球菌,其中对万古霉素耐药的肠球菌19株.2006年、2007年和2008年产超广谱β-内酰胺酶(ESBLs)大肠埃希菌分离率分别为41.7%、55.0%和56.8%,肺炎克雷伯菌分别为16.0%、22.4%和27.3%,产ESBLs菌株的耐药性远高于非ESBLs菌株.铜绿假单胞菌和不动杆菌属已出现多重耐药株.结论 老年患者分离致病菌耐药性高于非老年平均水平.定期进行耐药监测有助于了解老年患者细菌耐药性变迁,为临床经验用药提供理论依据.     

Evidence for a continuum of decreased vancomycin susceptibility in unselected Staphylococcus aureus clinical isolates

Some Staphylococcus aureus isolates have glycopeptide minimal inhibitory concentrations (MICs) in the susceptible range but have subpopulations that grow on >or=4 microg/mL vancomycin. Clinical laboratory methods for determining susceptibility have proven to be inadequate for detecting these strains. Among methicillin-resistant S. aureus (MRSA) and methicillin-susceptible S. aureus (MSSA) clinical isolates, 149 (66.2%) of 225 and 17 (56.6%) of 30, respectively, grew on brain-heart infusion (BHI) medium containing 2 microg/mL vancomycin; 17 (7.5%) of the MRSA and 2 (6.6%) of the MSSA isolates grew on BHI screening plates containing 4 microg/mL vancomycin. One isolate grew on plates containing 6 microg/mL vancomycin. This isolate escaped detection by routine testing but had a vancomycin MIC of 6 microg/mL when tested in BHI medium. This isolate also had decreased Triton X-100-induced autolysis and killing when incubated in broth media containing vancomycin, properties accorded to glycopeptide-intermediate S. aureus isolates. These observations suggest that glycopeptide-intermediate-like S. aureus isolates are circulating undetected and that a continuum of decreased susceptibility exists in unselected isolates.     

金黄色葡萄球菌对万古霉素耐药机制的初步研究

目的了解金黄色葡萄球菌对万古霉素耐药机制。方法按照美国临床实验室标准化委员会(NCCLS)标准,应用琼脂平板稀释法及MRSA特异性基因mecA的扩增鉴定MRSA,诱导产生万古霉素耐药株,然后以超声破碎法提取外膜蛋白(OMP),经聚丙烯酰胺凝胶电泳(SDS-PAGE)分析OMP的成分,分光光度法扫描仪测定相关膜蛋白的相对含量。结果耐万古霉素金葡菌菌株中,分子量为45KD和14KD的膜蛋白的相对含量较金葡菌ATCC25923株和对万古霉素敏感的MRSA少。结论提示45KD和14KD膜蛋白减少或缺失与金葡菌对万古霉素耐药可能有密切关系。     

烧伤患者创面感染金黄色葡萄球菌分离株耐药性及流行病学分析

目的对河北地区烧伤患者创面分离的120株金黄色葡萄球菌进行mecA和SCCmec检测分析MRSA耐药机制,为临床合理用药提供依据。方法在2009~2013年收治的烧伤患者创面中分离的120株金黄色葡萄球菌,采用头孢西丁纸片法进行MRSA筛选,对mecA基因,SCCmec和spa基因进行PCR扩增以及分型。结果 120株金黄色葡萄球菌中有74株为MRSA,占61.7%。药敏试验显示,MRSA对16种临床常见抗生素耐药率,超过85%的有7种,依次为苯唑西林（98.6%）,青霉素（96.0%）,环丙沙星（94.6%）,阿莫西林和头孢唑林（89.2%）,亚胺培南（87.8%）,庆大霉素（85.1%）,另有1株对万古霉素耐药。结论本组金黄色葡萄球菌MRSA检出率较高,并表现出较高的耐药性。MRSA具有的多重耐药性mecA基因密切关系。     

Epidemiological investigation of MRSA with antagonistic effects of beta-lactam antibiotic and vancomycin

The combination of vancomycin and beta-lactam antibiotic synergistically is known to act on vancomycin-susceptible Staphylococcus aureus (VSSA). But some MRSA with the antagonism in the combination of vancomycin and beta-lactam antibiotic was identified in Japan. We called the MRSA "beta-lactam antibiotic-induced vancomycin-resistant MRSA (BIVR)", to distinguish it from hetero-VISA. The percentage of hetero-VISA isolated in Japan that Hiramatsu et al. reported in The Lancet in 1997 was that of "candidate-hetero-VISA" because it did not satisfy the criteria for detection of hetero-VISA that they proposed. Therefore, except for Mu3, a strictly defined hetero-VISA strain has never been detected in Japan. However, BIVR is certainly detectable in Japan. We performed a retrospective study of BIVR in 189 MRSA strains isolated from blood between 1978 and 1999 at the same institution. To performed a retrospective study, 189 MRSA strains were divided such as 1978-1984 (45strains), 1985-1989 (45strains), 1990-1994 (49strains), 1995-1999 (50strains). MIC90 of anti-MRSA drugs according to above chronological transition were 2, 2, 2, 1 as vancomycin, 2, 1, 1, 1 as teicoplanin, and 8, 8, 1, 1 microgram/mL as arbekacin, respectively, and then the detection rate of BIVR was 2.2, 2.2, 6.1, 10.4%, respectively. The BIVR detection rate in MRSA isolated from blood at 14 institutions was 14.8% (12/81) in 1999-2002, and that of non-blood was 4.6% (42/905) (p < 0.001; chi 2-t examination). Of particular importance is that the percentage of BIVR isolated from blood is higher than that from non-blood, and the detection rate of BIVR from blood increases annually.     

Antimicrobial resistance and underlying mechanisms in Staphylococcus aureus isolates

Objective: To investigate the antimicrobial susceptibility of 97 clinical Staphylococcus aureus(S. aureus) strains against 14 antimicrobials and corresponding resistance mechanisms.Methods: The antimicrobial susceptibility of the isolates was determined using a disk diffusion method and antimicrobial resistance genes were screened by polymerase chain reaction. Mutations responsible for ciprofloxacin and rifampicin resistance were investigated by polymerase chain reaction and DNA sequencing.Results: All isolates were found to be susceptible to vancomycin. Various rates of resistance to penicillin(83.5%), ampicillin(77.3%), erythromycin(63.9%), tetracycline(16.5%), amoxicillin/clavulanic acid(16.5%), ciprofloxacin(15.5%), trimethoprim/sulfamethoxazole(15.5%), oxacillin(13.4%), fusidic acid(12.4%), rifampin(6.2%), clindamycin(6.2%), gentamicin(6.2%) and mupirocin(5.2%) were determined. In addition,different combinations of resistance genes were identified among resistant isolates.Ciprofloxacin resistant isolates had mutations in codon 84(Ser84 Leu) and 106(Gly106 Asp) in the gyr A gene. Mutations in grl A were mostly related to Ser80 Phe substitution. Leu466 Ser mutation in the rpo B gene was detected in all rifampin resistant isolates. All methicillin resistant S. aureus isolates were SCCmec type V.Conclusions: In conclusion, it was determined that the isolates were resistant to different classes of antimicrobials at varying rates and resistance was mediated by different genetic mechanisms. Therefore, continuous monitoring of resistance in S. aureus strains is necessary to control their resistance for clinically important antimicrobials.     

生鲜牛奶中金黄色葡萄球菌的分离及耐药性分析

目的 通过对山东、湖南等5省生鲜牛奶中的金黄色葡萄球菌进行耐药表型和耐药基因分析,了解我国生鲜牛奶中金黄色葡萄球菌的污染状况和耐药情况。方法 对采集的600份生鲜牛奶中分离的金黄色葡萄球菌进行MIC测定,并对9种耐药基因进行检测,对耐药表型和耐药基因携带状况进行分析。结果 生鲜牛奶中金黄色葡萄球菌分离率为26.17%;所有分离菌株对恩诺沙星和万古霉素敏感,对青霉素耐药,98.73%的分离菌株对阿莫西林耐药,大多数分离菌携带多种耐药基因。结论 分离的157株菌中有29株MRSA,其中有22株携带femA基因,应加强牛奶中耐药菌株的监测,为指导奶牛场安全合理用药和保障消费者食品安全提供依据。     

Emergence of teicoplanin resistance during therapy of Staphylococcus aureus endocarditis

Serial isolates of Staphylococcus aureus showing two- to eightfold increases in teicoplanin minimum inhibitory concentrations (MICs) and twofold or less increases in MICs of other glycopeptides were recovered from the blood of a patient with endocarditis in whom drug therapy was unsuccessful. Comparable resistance emerged during teicoplanin treatment of rabbits with endocarditis caused by the original susceptible parent strain. For the parent strain, spontaneous resistance to teicoplanin at concentrations of 2-10 times the MIC was detected in vitro at frequencies of 10(-7) to 10(-9). Similar results were found for isolates of S. aureus from other geographic locations. Resistance was constitutive and not plasmid mediated, and its acquisition was not associated with changes in cytoplasmic membrane proteins. Teicoplanin was less effective than vancomycin at inhibiting peptidoglycan synthesis in resistant strains, suggesting that there is differential interference with the access of teicoplanin to or interaction with its target(s). Alternatively, teicoplanin and vancomycin may differ in some detail(s) of their mechanism of action against S. aureus.     

Methicillin resistance among Trinidadian isolates of community and hospital strains of Staphylococcus aureus and their patterns of resistance to non-beta-lactam antibiotics

The prevalence of methicillin-resistant Staphylococcus aureus (MRSA) strains in Trinidad and the extent of their resistance to other antimicrobial agents in hospital-acquired and community-acquired infections were evaluated over a 2-year period. A total of 450 S. aureus strains were isolated from different patients. The prevalence of methicillin resistance among S. aureus strains was 9.8% (44/450). The proportion of MRSA isolated from hospital sources and community sources was 12.5% (38/305) and 4.1% (6/145), respectively (P < 0.05). The resistant rates of MRSA to the non-beta-lactam antibiotics were as follows: 93.2% resistance to tetracycline, 68.2% to erythromycin, 61.4% to gentamicin, 45.5% to co-trimoxazole, and 20.5% to ciprofloxacin. No MRSA resistant to vancomycin was observed in this study. Study results showed significant increases in MRSA in hospital, 2% in 1995 to 12.5% in 1998 (P < 0.05), and community, 0% in 1995 to 4.1% in 1998 (P < 0.05). It has become apparent that infection control and surveillance initiatives must be focused now on the community in order to monitor and limit the spread of this new and expanding reservoir of MRSA.