In vitro activities of quinupristin/dalfopristin and eight other antimicrobial agents against 360 clinical isolates from Korea

The emergence of multi-drug resistant gram-positive cocci such as methicillin-resistant (MR) staphylococci, vancomycin-resistant (VR) enterococci, and vancomycin-intermediate resistant S. aureus (VISA) has given new urgency to the development of new antimicrobial agents. One of these is quinupristin/dalfopristin (Q/D). We decided to determine the susceptibility of gram-positive cocci isolated at two university hospitals in Seoul to Q/D and compare the results with eight other antimicrobial agents. We investigated 120 isolates of S. aureus including 49 MRSAs and one VISA, 120 isolates of coagulase negative staphylococci (CNS), 64 E. faecalis and 56 E. faecium, including seven strains of VR E. faecium. Minimum inhibitory concentrations (MICs) and minimal bactericidal concentrations (MBCs) for several antimicrobials, including vancomycin and Q/D, were determined by broth microdilution. All S. aureus including VISA were susceptible to Q/D. Q/D MIC90 for both methicillin-susceptible S. aureus (MSSA) and MRSA was 0.25 g/mL. 49 (87.5%) of 56 E. faecium including six of seven VR E. faecium were susceptible to Q/D. E. faecalis were not susceptible to Q/D (only 1.5% susceptible), but were inhibited by ampicillin (94% susceptible) or vancomycin (95%). CNS was susceptible to Q/D (96% susceptible) and vancomycin (100% susceptible). One of 38 staphylococci and two of 17 E. faecium were tolerant to Q/D. In conclusion, Q/D showed excellent activity against all species of gram-positive cocci including MRSA, VISA, and VR E. faecium except E. faecalis, and may provide a valuable option for the treatment of infections caused by these emerging nosocomial pathogens of gram-positive cocci.     

1999-2006年北京朝阳医院革兰阳性球菌耐药性分析

目的 探讨北京朝阳医院1999-2006年临床分离的革兰阳性球菌的耐药变迁,以指导临床合理使用抗菌药物.方法 采用MIC法进行抗菌药物敏感性试验,以WHONET5.3软件分析数据.结果 6192株临床分离的革兰阳性球菌中,前4位病原菌依次为凝同酶阴性葡萄球菌、金黄葡萄球菌、粪肠球菌、屎肠球菌.耐甲氧西林金黄葡萄球菌(MRSA)、耐甲氧西林凝固酶阴性葡萄球菌(MRCNS)平均检出率分别为88.4%、86.9%,金黄葡萄球菌对青霉素、氨苄西林耐药率最高,8年间始终保持在90.0%以上.未发现对万古霉素耐药或中介的金黄葡萄球菌或凝固酶阴性葡萄球菌.2003年首次分离耐万古霉素肠球菌(VRE),至2006年共发现30株VRE,其中13株为耐万古霉索粪肠球菌,均为VanB基因型;17株为耐万古霉素屎肠球菌,均为VanA基因型,耐万古霉素屎肠球菌分离率呈上升趋势.对于粪肠球菌活性最高的是万古霉素、氨苄西林、青霉素,敏感率分别为98.7%、95.7%、85.6%.但是青霉素敏感性略有下降,从94.3%降至84.6%.克林霉素的耐药率8年中始终维持在99.0%以上.屎肠球菌对红霉素、克林霉素的耐药率均达95.0%以上,对青霉素、氨苄西林、环丙沙星的耐药率均大于90.0%.屎肠球菌最为敏感的药物是万古霉素,对四环素敏感性出现上升的趋势,从27.8%升到82.6%.结论 万古霉素对临床常见的革兰阳性菌保持很高的活性,发现30株耐万古霉素的肠球菌.     

In vitro activity of vancomycin and teicoplanin against gram-positive cocci]

The activities of vancomycin and teicoplanin against 148 strains of Gram-positive cocci were tested using agar diffusion and liquid microdilution MIC determination. Tested strains included 84 staphylococci, 32 S. aureus, 52 coagulase-negative staphylococci (CNS), 52 enterococci, and 12 streptococci. Most strains (136) were susceptible to both agents, with inhibition diameters of 17 mm or more. MRSA strains exhibited lower geometric MIC means with teicoplanin (0.90 micrograms/ml) than with vancomycin (1.79 micrograms/ml); this difference was found for methicillin-susceptible S. aureus strains (1.07 and 1.38 micrograms/ml for teicoplanin and vancomycin, respectively). In contrast, methicillin-susceptible and methicillin-resistant strains of CNS exhibited similar MICs (1.60 micrograms/ml approximately). Enterococci were more susceptible to teicoplanin (MIC 0.25 micrograms/ml) than to vancomycin (MIC 1.35 micrograms/ml). Both vancomycin and teicoplanin were thus found to be consistently effective against Gram-positive cocci; however, teicoplanin proved more effective than vancomycin against enterococci and methicillin-resistant S. aureus strains and may therefore be a valuable therapeutic alternative for these multiresistant organisms.     

Nationwide German multicenter study on prevalence of antibiotic resistance in staphylococcal bloodstream isolates and comparative in vitro activities of quinupristin-dalfopristin

Antibiotic-resistant gram-positive bacteria have become an increasing problem in the last two decades. In order to evaluate the prevalence of antibiotic resistance in staphylococcal bloodstream isolates in Germany, 2,042 staphylococci collected in 21 tertiary-care hospitals were investigated during a 3-year period (March 1996 to March 1999). Altogether, 1,448 S. aureus isolates and 594 coagulase-negative staphylococci (CoNS) that comprised 13 different species were included. Furthermore, the antistaphylococcal activities of quinupristin-dalfopristin were compared with those of eight other compounds by the broth microdilution method. The rates of oxacillin resistance in Staphylococcus aureus, S. epidermidis, S. haemolyticus, and other CoNS were 13.5, 69, 90, and 34%, respectively. In oxacillin-resistant strains high rates of resistance (up to 100%) to erythromycin, clindamycin, ciprofloxacin, and gentamicin were also observed. However, no strain appeared to be resistant to vancomycin or quinupristin-dalfopristin. The streptogramin combination exhibited excellent in vitro activity against all staphylococcal species tested, regardless of the patterns of resistance to other drug classes. In terms of MICs at which 90% of the isolates are inhibited, quinupristin-dalfopristin was 2 times more active against S. aureus isolates, 4 to 16 times more active against S. haemolyticus, and 8 to 32 times more active against S. epidermidis than vancomycin or teicoplanin.     

Evaluation of the VITEK 2 system for identification and antimicrobial susceptibility testing of medically relevant gram-positive cocci

A study was conducted to evaluate the new VITEK 2 system (bioMérieux) for identification and antibiotic susceptibility testing of gram-positive cocci. Clinical isolates of Staphylococcus aureus (n = 100), coagulase-negative staphylococci (CNS) (n = 100), Enterococcus spp. (n = 89), Streptococcus agalactiae (n = 29), and Streptococcus pneumoniae (n = 66) were examined with the ID-GPC identification card and with the AST-P515 (for staphylococci), AST-P516 (for enterococci and S. agalactiae) and AST-P506 (for pneumococci) susceptibility cards. The identification comparison methods were the API Staph for staphylococci and the API 20 Strep for streptococci and enterococci; for antimicrobial susceptibility testing, the agar dilution method according to the procedure of the National Committee for Clinical Laboratory Standards (NCCLS) was used. The VITEK 2 system correctly identified to the species level (only one choice or after simple supplementary tests) 99% of S. aureus, 96.5% of S. agalactiae, 96.9% of S. pneumoniae, 92.7% of Enterococcus faecalis, 91.3% of Staphylococcus haemolyticus, and 88% of Staphylococcus epidermidis but was least able to identify Enterococcus faecium (71.4% correct). More than 90% of gram-positive cocci were identified within 3 h. According to the NCCLS breakpoints, antimicrobial susceptibility testing with the VITEK 2 system gave 96% correct category agreement, 0.82% very major errors, 0.17% major errors, and 2.7% minor errors. Antimicrobial susceptibility testing showed category agreement from 94 to 100% for S. aureus, from 90 to 100% for CNS, from 91 to 100% for enterococci, from 96 to 100% for S. agalactiae, and from 91 to 100% for S. pneumoniae. Microorganism-antibiotic combinations that gave very major errors were CNS-erythromycin, CNS-oxacillin, enterococci-teicoplanin, and enterococci-high-concentration gentamicin. Major errors were observed for CNS-oxacillin and S. agalactiae-tetracycline combinations. In conclusion the results of this study indicate that the VITEK 2 system represents an accurate and acceptable means for performing identification and antibiotic susceptibility tests with medically relevant gram-positive cocci.     

Pharmacodynamic comparison of linezolid, teicoplanin and vancomycin against clinical isolates of Staphylococcus aureus and coagulase-negative staphylococci collected from hospitals in Brazil.

Pharmacodynamic exposures, measured as the ratio of steady-state total drug area under the curve to MIC (AUC/MIC), were modelled using a 5000-patient Monte-Carlo simulation against 119 non-duplicate clinical isolates of Staphylococcus aureus and 82 coagulase-negative staphylococci (CNS) collected from hospitals in Brazil between 2003 and 2005. Pharmacodynamic targets included an AUC/MIC >82.9 for linezolid and >345 for teicoplanin and vancomycin, as well as a free drug AUC/MIC >180 for vancomycin. The cumulative fractions of response (CFRs) against all S. aureus isolates were 96.0%, 30.1%, 71.6%, 48.0% and 65.1% for linezolid 600 mg every 12 h, teicoplanin 400 mg every 24 h and 800 mg every 24 h, and vancomycin 1000 mg every 12 h and every 8 h, respectively. Using a free drug target for vancomycin improved the CFR to 94.6% for the high-dose regimen, but did not substantially alter results for the lower dose. CFRs against all CNS isolates were 97.8%, 13.4%, 34.6%, 10.9% and 31.3%, respectively, for the same antibiotic regimens. The CFR was reduced for all compounds among the methicillin-resistant isolates, except for linezolid against methicillin-resistant CNS. Sensitivity analyses did not alter the final order of pharmacodynamic potency against these isolates. Although higher doses of vancomycin and teicoplanin increased the CFR, the likelihood of achieving bactericidal targets was still lower than with linezolid. The results for the high-dose vancomycin regimen were highly dependent on the pharmacodynamic target utilised. These data suggest that linezolid has a greater probability of attaining its requisite pharmacodynamic target than teicoplanin and vancomycin against these staphylococci.     

Rapid Identification of Methicillin-Resistant Staphylococcus aureus from Positive Blood Cultures by Real-Time Fluorescence PCR

Methicillin-resistant Staphylococcus aureus septicemia is associated with significant morbidity and mortality and requires treatment with intravenous glycopeptides. For blood cultures positive for gram-positive cocci, 24 to 48 h is required for the detection of S. aureus bacteremia and the provision of antibiotic susceptibility testing results. We describe a molecular biology-based assay that requires 2 h from the time of initial positivity of blood cultures. The assay correctly detected 96% of the S. aureus isolates including all methicillin-resistant S. aureus isolates. Clinical data collected during the study suggest that 28% of patients with S. aureus bacteremia do not receive early and appropriate treatment and that 10% of patients may initially be receiving inappropriate glycopeptide treatment.     

A novel luminometer for rapid antimicrobial susceptibility tests on gram-positive cocci by ATP bioluminescence

The susceptibility of 130 clinical isolates of gram-positive cocci to a wide range of antimicrobial agents was assessed by ATP bioluminescence in a 4-h test. ATP assays were performed on a novel luminometer, the Amerlite Analyser, which measures luminescence from microtitration trays. For most organisms tested, there was good correlation (greater than 90%) with conventional MIC values estimated on 18-h cultures. However, a problem was found with detection of penicillin resistance in Staphylococcus aureus by the ATP method, 13% of strains showing major disagreement. Methicillin resistance of S. aureus was shown reliably for most strains (94%) by ATP assay, provided they were incubated at 30 degrees C. The Amerlite Analyser offers the potential for the development of a semi-automated antimicrobial susceptibility test, with a significant reduction in reagent costs when compared with previously described bioluminescence protocols.     

European survey of glycopeptide susceptibility in Staphylococcus spp.

Objectives: To reassess the relative potencies of teicoplanin and vancomycin following several years of clinical usage.
Methods: The glycopeptide susceptibilities of clinical isolates of staphylococci collected from 70 hospitals in 1995 were determined using NCCLS (National Committee for Clinical Laboratory Standards) methods.
Results: In total, 2885 isolates of Staphylococcus aureus and 1480 isolates of coagulase-negative staphylococci were collected. S. aureus was significantly less susceptible to vancomycin (MIC₅₀ 1 mg/L) than teicoplanin (MIC₅₀ 0.5 mg/L), but the reverse was the case for S. haemolyticus and S. epidermidis . No S. aureus isolate was resistant (≥32 mg/L) to either glycopeptide, but nine isolates of coagulase-negative staphylococci had an MIC of teicoplanin of 32 mg/L. Respiratory isolates of S. aureus were less susceptible to glycopeptides than those from other sites. Staphylococci from Belgium and Italy were less susceptible to teicoplanin than isolates from other countries.
Conclusions: This European survey shows that in 10 years of clinical use there have been no major changes in the susceptibility of staphylococci to the glycopeptides.     

Antimicrobial activity of fusidic acid and disk diffusion susceptibility testing criteria for gram-positive cocci.

The in vitro activity of fusidic acid was assessed and was compared with those of cloxacillin, cefamandole, vancomycin, teicoplanin, ofloxacin, ciprofloxacin, pefloxacin, and fleroxacin against 500 gram-positive cocci: 151 Staphylococcus aureus, 197 coagulase-negative staphylococci, and 152 Enterococcus faecalis strains. All clinical isolates were concomitantly tested by disk diffusion and agar dilution procedures as outlined by the National Committee for Clinical Laboratory Standards. The results with fusidic acid were further analyzed by regression line and error rate-bounded methods. With control American Type Culture Collection organisms, the values were within the limits of the National Committee for Clinical Laboratory Standards or published limits. The incidence of resistance to fusidic acid was 0.7% for S. aureus, 2.5% for coagulase-negative staphylococci, and 99.3% for E. faecalis. The correlation coefficient between the results of disk diffusion and agar dilution tests with fusidic acid was 0.90. Current interpretive criteria for susceptibility to fusidic acid (i.e., MIC of < 2 micrograms/ml and inhibitory zone of 20 mm) gave 1% false susceptibility (all strains being E. faecalis). This error rate is practically eliminated if a zone diameter of 21 mm is considered the breakpoint for susceptibility.     

Evaluation of the Hyplex BloodScreen Multiplex PCR-Enzyme-linked immunosorbent assay system for direct identification of gram-positive cocci and gram-negative bacilli from positive blood cultures

We evaluated the Hyplex BloodScreen PCR-enzyme-linked immunosorbent assay (ELISA) system (BAG, Lich, Germany), a new diagnostic test for the direct identification of gram-negative bacilli and gram-positive cocci from positive blood cultures, with 482 positive BACTEC 9240 blood culture bottles. The test involves amplification of the bacterial DNA by multiplex PCR and subsequent hybridization of the PCR product to specific oligonucleotide probes in an ELISA-based format. The available probes allow the separate detection of Escherichia coli, Pseudomonas aeruginosa, Enterobacter aerogenes, Klebsiella spp., Staphylococcus aureus, Staphylococcus epidermidis, Enterococcus faecalis/Enterococcus faecium, Streptococcus pyogenes, and Streptococcus pneumoniae and the staphylococcal mecA gene. The Hyplex BloodScreen test showed an overall sensitivity of 100% for the identification of gram-negative bacilli and 96.6 to 100% for the identification of gram-positive cocci (S. aureus, 100%; S. epidermidis, 97.2%; Enterococcus faecalis/Enterococcus faecium, 96.6%; and Streptococcus pneumoniae, 100%). The specificities of the test modules ranged from 92.5 to 100% for gram-negative bacilli and 97.7 to 100% for gram-positive cocci (Escherichia coli, 92.5%; Pseudomonas aeruginosa, 98.5%; Klebsiella spp., 100%; Enterobacter aerogenes, 100%; S. aureus, 100%, S. epidermidis, 97.7%; Enterococcus faecalis/Enterococcus faecium, 99.6%; Streptococcus pyogenes, 100%; and Streptococcus pneumoniae, 99.3%). The result of the mecA gene detection module correlated with the result of the phenotypic oxacillin resistance testing in all 38 isolates of Staphylococcus aureus investigated. In conclusion, the Hyplex BloodScreen PCR-ELISA system is well suited for the direct and specific identification of the most common pathogenic bacteria and the direct detection of the mecA gene of Staphylococcus aureus in positive blood cultures.     

脑脊液病原菌变迁和耐药性分析

目的了解临床脑脊液培养阳性患者病原菌分布及其耐药情况。方法对2002—2008年临床脑脊液培养病原菌阳性患者标本进行回顾性统计分析;按常规方法进行细菌分离和鉴定;细菌药物敏感试验采用Kirby—Bauer纸片扩散法。结果分离出细菌97株,其中革兰阳性球菌占54．63％,革兰阴性菌占28．87％：新型隐球菌占13．40％。最常见的6种感染菌分别为凝固酶阴性葡萄球菌（40．21％）、不动杆菌属（8．25％）、铜绿假单胞菌（6．19％）、金黄色葡萄球菌（5．15％）、肺炎克雷伯菌（5．15％）、肠球菌属（5．15％）;耐甲氧西林凝固酶阴性葡萄球菌（MRSCN）和耐甲氧西林金黄色葡萄球菌（MRSA）的检出率分别是89．7％和80．0％。细菌对常用抗生素耐药性较高,未见万古霉素耐药的葡萄球菌;美洛培南以及头孢哌N／舒巴坦对革兰氏阴性杆菌有良好的抗菌活性。结论近6年来细菌性脑膜炎患者病原菌以革兰阳性球菌为主,主要为医院获得性细菌性脑膜炎感染。检出病原菌对常用抗生素耐药性较高,临床需警惕新型隐球菌的高发病趋势。     

Antimicrobial susceptibility of Gram-positive bacteria isolated from European medical centres: results of the Daptomycin Surveillance Programme (2002–2004)

The antimicrobial susceptibility patterns of 9322 contemporary (2002-2004) gram-positive bacterial isolates collected from 31 medical centres in 14 countries in Europe were evaluated by broth microdilution methods according to CLSI guidelines. The isolates collected comprised Staphylococcus aureus (4842 isolates), coagulase-negative staphylococci (CoNS; 1942 isolates), Enterococcus faecalis (1147 isolates), Enterococcus faecium (391 isolates), beta-haemolytic streptococci (660 isolates) and viridans group streptococci (340 isolates). The organisms were tested against daptomycin and more than 20 comparator agents in Mueller-Hinton broth, supplemented with calcium to 50 mg/L when testing daptomycin. Overall, methicillin (oxacillin) resistance rates were 26.7% and 77.0% for S. aureus (MRSA) and CoNS, respectively, and the vancomycin resistance rate among enterococci was 6.1%. MRSA rates varied from 0.6% in Sweden to 40.2-43.0% in Belgium, Greece, Ireland, the UK and Israel, and VRE rates varied from 0% in Switzerland to 21.2% in Ireland. More than 99.9% of isolates tested were considered susceptible to daptomycin according to breakpoints established by the United States Food and Drug Administration and the CLSI. Daptomycin was active against all gram-positive species, with the highest MIC being 2, 8, 0.5 and 2 mg/L for staphylococci, enterococci, beta-haemolytic streptococci and viridans group streptococci, respectively. Daptomycin activity was not influenced adversely by resistance to other agents among staphylococci or enterococci. This novel lipopeptide (daptomycin) appears to be an excellent alternative therapeutic option for serious infections caused by multidrug-resistant gram-positive organisms isolated in Europe.     

Multiplex PCR for the detection of genes encoding aminoglycoside modifying enzymes and methicillin resistance among Staphylococcus species

We developed multiplex polymerase chain reaction (PCR) to detect aac(6 ')/aph(2 "), aph(3 ')-IIIa, and ant(4 ')-Ia, the genes encoding the most clinically relevant amino-glycoside modifying enzymes (AME), and simultaneously, the methicillin resistant gene, mecA, in Staphylococcus species. Clinical isolates of 45 S. aureus and 47 coagulase negative staphylococci (CNS) from tertiary university hospitals were tested by conventional susceptibility testing, using the agar dilution method and by multiplex PCR. Of a total of 92 isolates, 61 isolates were found to be methicillin-resistant. Of these, 54 isolates (89%) were found to be harboring mecA. Seventy-five percent of the 92 isolates demonstrated resistance to at least one of the aminoglycosides tested. Moreover, resistance to aminoglycosides was closely associated with methicillin-resistance (p<0.05). The most prevalent AME gene was aac(6 ')/aph(2 ") which was found in 65% of the isolates, and ant(4 ')-Ia and aph(3 ')-IIIa were present in 41% and 9% of the isolates, respectively. The concordance between methicillin-resistance and the presence of mecA gene was 98% in S. aureus and 81% in CNS. The concordance between gentamicin resistance and the presence of aac(6 ')/aph(2 ") gene was 100% in S. aureus and 85% in CNS. The multiplex PCR method that we developed appears to be both a more rapid and reliable than conventional method.     

Molecular Epidemiology of Oxacillin-resistant Staphylococcus aureus and in vitro Activity of Glycopeptides against Staphylococcus species

Oxacillin resistant Staphylococcus aureus and coagulase negative Staphylococcus species (MRSA and MRSCoN)have become major pathogens in nosocomial infections.The first MRSA isolate in the world was identified in En gland in 1961 [1]. Since that tim…     

Early Screening of oxacillin-resistant Staphylococcus aureus and Staphylococcus epidermidis from blood culture

The timely detection of blood-borne pathogens is one of the most important functions of the microbiology laboratory. Recently, methicillin-resistant staphylococci have become the most important pathogens seen by the laboratory. The purpose of this study was to evaluate Staphy agar, a novel screening medium, for the detection methicillin-resistant Staphylococcus aureus, S. epidermidis, or other coagulase-negative staphylococci (CNS) from positive blood cultures showing Gram-positive cocci in clusters. Eighty-six blood cultures that yielded Gram-positive cocci in clusters were included in this study. The organisms were finally identified by the Vitek system, and oxacillin resistance was confirmed by polymerase chain reaction (PCR)-based mecA gene detection. The identification and oxacillin resistance of all S. aureus strains showed complete agreement with the Vitek and PCR results. The presumptive detection of S. epidermidis and other CNS were consistent with the Vitek system in 94.7%, and the screening of oxacillin resistance was consistent with the result of PCR in 92.1% of 38 strains. The Staphy agar method is reliable and rapid for differentiating Gram-positive cocci in clusters in blood and for determining their methicillin resistance.     

Rapid identification of Staphylococcus aureus and the mecA gene from BacT/ALERT blood culture bottles by using the LightCycler system

One hundred BacT/ALERT blood culture bottles growing gram-positive cocci in clusters were cultured and studied by LightCycler PCR for the sa442 and mecA genes. PCR was 100% sensitive and specific for detecting Staphylococcus aureus and methicillin resistance in S. aureus but was less accurate for methicillin resistance in coagulase-negative staphylococci.     

Screening for methicillin resistance in Staphylococcus aureus and coagulase-negative staphylococci: an evaluation of three selective media and Mastalex-MRSA latex agglutination

Laboratory confirmation of MRSA is important for the implementation of infection control; conventional screening culture methods take up to five days for confirmation. The purpose of this study is to ascertain the efficiency of three selective media for growth of methicillin-resistant Staphylococcus aureus (MRSA) before and after enrichment in salt broth, and to evaluate the Mastalex-MRSA latex agglutination kit for detection of methicillin resistance. Screening swabs were collected from 63 patients, yielding 125 S. aureus isolates and 40 coagulase-negative staphylococcus (CNS) isolates. Selective media used were mannitol salt agar (MSA), Baird-Parker agar with ciprofloxacin (BPC) and bromocresol purple (BCPA). Polymerase chain reaction (PCR) for mecA gene detection was used as the reference standard for evaluation of the Mastalex-MRSA assay, which was also evaluated on colonies of S. aureus from the selective media. No significant difference was found in efficiency of MRSA isolation among the selective media. Pre-enrichment in the salt broth did not enhance isolation of MRSA. Methicillin-sensitive S. aureus and CNS were significantly inhibited in all selective media (P<0.05). Only BPC significantly selected out methicillin-resistant CNS (P<0.01). Mastalex-MRSA was 97% specific and sensitive for the detection of MRSA. It was 65% sensitive and 100% specific in detecting methicillin resistance in CNS. In conclusion, all selective media performed equally well (MRSA isolation rate of approximately 80%). Mastalex-MRSA provided rapid and reliable detection of MRSA from selective media, reducing the time required for confirmation of this organism.     

血培养常见菌株的分布及金黄色葡萄球菌耐药性的分析

目的调查同济医院2006年1月至2008年12月血培养中常见非重复分离菌株的构成;分析金黄色葡萄球菌对常用抗菌药物的耐药性。方法采用WHONET5．4软件分析连续3年血培养中的非重复分离菌株的分布;采用K-B纸片法测定金黄色葡萄球菌对常用抗菌药物的敏感性。结果2006年1月至2008年12月共分离细菌1336株,其中革兰阳性球菌占58．5％（781／1336）、革兰阴性杆菌占37．2％（497／1336）、真菌占4．27％（57／1336）。分离的前10位菌株依次为凝固酶阴性葡萄球菌（CNS,40．42％）、大肠埃希菌（13．47％）、肠球菌属（5．54％）、克雷伯菌属（4．94％）、金黄色葡萄球菌（4．34％）、草绿链球菌（4．34％）、真菌（4．27％）、沙门菌属（3．59％）、铜绿假单胞菌（3．29％）、嗜麦芽窄食单胞菌（3．14％）。金黄色葡萄球菌共58株,其中甲氧西林耐药金黄色葡萄球菌（methicillinresistantStaphylococcusoltl-eus。MRSA）占44．8％（26／58）。MRSA对头孢菌素类、氨苄西林／舒巴坦、红霉素、克林霉素、复方新诺明、庆大霉素和左氧氟沙星、磷霉素、利福平耐药率明显高于甲氧西林敏感的金黄色葡萄球菌（methicillin—susceptibleStaphylococcuso,uFeus,MSSA）,且差异具有统计学意义（P〈0．001）。未发现对万古霉素和替考拉宁不敏感的菌株。结论本院血培养分离株中,凝固酶阴性葡萄球菌仍占据第一位。金黄色葡萄球菌占分离菌株第五位,其中MRSA检出率较高,且耐药性严重。MRSA病区的分布及耐药谱分析提示可能存在MRSA的克隆传播。     

Identification of Staphylococcus aureus and determination of methicillin resistance directly from positive blood cultures by isothermal amplification and a disposable detection device

A simple, rapid, and user-friendly procedure has been developed to identify Staphylococcus aureus and determine its methicillin resistance directly from gram-positive cocci in cluster-containing blood culture medium. The specimens were diluted and heated prior to amplification of the nuc and mecA genes with isothermal helicase-dependent amplification. Amplicons were detected using a disposable detection device. The analytical sensitivity of the assays was 50 CFU per reaction, and the clinical sensitivity and specificity were both 100% for S. aureus detection and 100% and 98% for methicillin resistance determination, respectively.