253株金黄色葡萄球菌耐药现状分析

目的 了解医院金黄色葡萄球菌临床分布情况及其对常用抗菌药物的耐药率,为临床合理使用抗菌药物提供依据.方法 回顾分析医院2010年5月至2011年4月检出的金黄色葡萄球菌,采用VITEK-AMS全自动微生物分析仪进行菌种鉴定和药敏分析.结果 共检出金黄色葡萄球菌253株,菌株的主要来源为痰130株(51.4％)、血液39株(15.4％)、创面24株(9.5％);菌株主要科室分布前3位是神内科35株(13.8％)、ICU30( 11.8％)、脑外科26株(10.3％);其中耐甲氧西林金黄色葡萄球菌( MRSA)为165株(65.2％),MRSA对多种抗菌药物耐药率＞70.0％,MSSA为88株(34.8％),对除青霉素、红霉素外的大多数抗菌药物敏感,未发现耐万古霉素菌株.结论 MRSA检出率高,耐药现状严重,应加强对金黄色葡萄球菌耐药性的监测,并根据药敏试验结果合理使用抗菌药物.     

Determination of methicillin resistance in clinical strains of Staphylococcus aureus in routine microbiological diagnostics

The aim of this study was to compare the results of two methods: disc-diffusion test and ATB STAPH 5 (version 2000) test applied for determination of methicillin-resistant staphylococci. One hundred and twenty S. aureus strains isolated from clinical specimens in microbiological laboratory of Medical University in Warsaw were investigated. Identification and drug resistance were determined using automatic ATB Expression System. We compared the results of methicillin-resistant S. aureus detection by disc-diffusion method (oxacillin 1 microg) and ATB STAPH 5; version 2000 (bioMérieux sa). In the case of 116 strains S. aureus identical results were obtained in both methods, 4 strains gave inconsistent results in these two methods. Results that were obtained show that the ATB STAPH 5 (version 2000) test is as useful for routine determination of MRSA and MSSA strains as the disc-diffusion method, and may be used alternatively.     

Chromosomal penicillin resistance in Staphylococcus aureus strains of phage group II

The markers coding for serotype B penicillinase (PcB) in wild type strains of group II of S. aureus behaved as chromosal characters in 6 out of 7 cases. The PcB markers could be transduced to group II strains, and with the help of restriction deficient mutants also to some strains of group I. No extrachromosomal DNA could be detected in the transductants. The low frequency of transduction of chromosomal markers as well as the high restriction barrier seem to limit the spread of these markers outside group II.     

74例金黄色葡萄球菌乳腺炎的耐药性分析

目的分析哺乳期乳房脓肿患者的金黄色葡萄球菌的耐药情况,指导临床合理使用抗菌药物。方法将厦门市妇幼保健院乳腺门诊及病房2009年2月至2011年1月抽取的128例哺乳期乳房脓肿患者的乳腺脓液接种于哥伦比亚血平板,置35℃培养箱,过夜孵育18~24 h。革兰阳性球菌,触酶阳性,血浆凝固酶试验(+),必要时采用ATB-Expression细菌鉴定系统确认。用K-B纸片法检测其对苯唑西林等10种抗菌药物的敏感度。结果 128例检出细菌86例,阳性率67.2%,其中检出74株金黄色葡萄球菌(86.0%),其对青霉素、红霉素和克林霉素有较强的耐药性,耐药率分别为94.6%、64.9%和59.5%;耐苯唑西林19株(25.7%),对复方新诺明、磷霉素和庆大霉素较为敏感,对万古霉素、替考拉宁和左旋氧氟沙星100%敏感。结论哺乳期乳房脓肿致病菌主要为金黄色葡萄球菌,耐甲氧西林金黄色葡萄球菌(MRSA)占25.7%,其耐药情况不容忽视,青霉素类、大环内酯类等耐药率较高不能作为经验用药。建议临床使用抗菌药物前及时送检乳腺脓液细菌培养,以药敏结果指导临床合理经济用药。     

耐甲氧西林金黄色葡萄球菌的分布及耐药性分析

目的分析医院耐甲氧西林金黄色葡萄球菌（MRSA）的分布及耐药情况,为临床治疗金黄色葡萄球菌医院感染提供科学依据。方法对618株金黄色葡萄球菌进行常规鉴定,用K—B法对其进行药敏试验。结果5年MRSA的平均检出率为51．9％（321／618）,MRSA感染高发主要科室为ICU、神经外科、神经内科,MRSA检出率前三位的科室为神经外科（84．1％）、ICU（76．3％）、呼吸内科（61．3％）,标本来源主要为痰液,占67．3％,检出率82．4％。MRSA对万古霉素、替考拉宁、利奈唑胺保持100％敏感,对氯霉素、米诺环素、复方新诺明等的耐药率较低,对其他药物都保持了65％以上的高耐药率。结论对重点科室监控,合理使用抗生素,严格执行无菌操作,采取有效的消毒隔离,尽量减少侵袭性操作等措施是控制并减少MRSA感染的重要环节。     

Naturally occurring drug resistance plasmids in hospital strains of Staphylococcus aureus

A genetic analysis of multiply inorganic salts and antibiotic--resistant strains of Staphylococcus aureus was performed. Experiments designed to show reversion of organisms to antibiotic and inorganic salt susceptibility, as well as studies on the influence of ultraviolet irradiation of phage on the transduction frequencies of the resistance markers, indicated that determinants of chloramphenicol, tetracycline, aminoglycoside antibiotics, inorganic salts, and penicillin resistance in hospital strain are present on separate plasmids. Transduced by us plasmids pN742 and pN794 determined resistance to neomycin, kanamycin, paromomycin, lividomycin and streptomycin.     

Chlorine resistance of strains of Staphylococcus aureus isolated from poultry processing plants

Strains of Staphylococcus aureus which colonize defeathering machinery and become endemic within poultry processing plants appear to be resistant to the normal cleaning and disinfection processes. The resistance of endemic strains to chlorine was compared with that of isolates from the natural skin flora of poultry. Endemic strains were almost eight times more resistant and this was due primarily to their ability to grow in macroclumps but also to the production of an extracellular slime layer.     

The molecular characteristic of Staphylococcus aureus and Staphylococcus epidermidis strains isolated from clinical sources

The aim of study was the molecular characteristic of S. aureus and S. epidermidis isolates obtained from skin surface, wounds, deep tissues of hospitalized patients and from skin surface of non-hospitalized patients. Genes encoding virulence factors were examined using PCR reaction and specific primers. Genes encoding adhesinsfnbA and cna and gene eta for epidermolytic toxin were mostly present in S. aureus isolates coming from wounds and deep tissues compared to these from skin surface. Gene atlE encoding autolysin of S. epidermidis was detected in all studied isolates, whereas gene icaAB was present in almost all isolates. Comparison of results obtained by PCR and conventional method of the resistance to methicillin estimation showed discrepances suggesting the need for using of both methods in some clinically difficult cases of S. aureus infection.     

Molecular characteristics of community-associated methicillin-resistant Staphylococcus aureus strains for clinical medicine

Infections caused by methicillin-resistant S. aureus strains are mainly associated with a hospital setting. However, nowadays, the MRSA infections of non-hospitalized patients are observed more frequently. In order to distinguish them from hospital-associated methicillin-resistant S. aureus (HA-MRSA) strains, given them the name of community-associated methicillin-resistant S. aureus (CA-MRSA). CA-MRSA strains most commonly cause skin infections, but may lead to more severe diseases, and consequently the patient’s death. The molecular markers of CA-MRSA strains are the presence of accessory gene regulator (agr) of group I or III, staphylococcal cassette chromosome mec (SCCmec) type IV, V or VII and genes encoding for Panton–Valentine leukocidin (PVL). In addition, CA-MRSA strains show resistance to β-lactam antibiotics. Studies on the genetic elements of CA-MRSA strains have a key role in the unambiguous identification of strains, monitoring of infections, improving the treatment, work on new antimicrobial agents and understanding the evolution of these pathogens.     

Antiseptic susceptibility and distribution of antiseptic-resistance genes in methicillin-resistant Staphylococcus aureus

We examined the antiseptic susceptibilities and distribution of antiseptic-resistance genes qacA and smr in 98 isolates of methicillin-resistant Staphylococcus aureus obtained in 1992. Seventy-one strains were resistant to antiseptics. The qacA and smr genes were detected in 10 and 20 strains, respectively. The remaining 41 strains without qacA and smr were divided into two groups that exhibited low-level (n = 22) and high-level (n = 19) resistance to acriflavin. DNA cloning and sequencing suggested that norfloxacin-resistance gene norA was responsible for the high-level resistance to acriflavin. Our results indicated that four or more antiseptic-resistance genes exist in methicillin-resistant S. aureus and that antiseptic-resistant methicillin-resistant S. aureus strains without qacA and smr are widely spread in Japan.     

Detection of low-enterotoxin-producing Staphylococcus aureus strains

Culture supernatant fluids from 26 (23.6%) monkey feeding test-positive Staphylococcus aureus strains, negative for enterotoxins by gel diffusion, were positive by enzyme-linked immunosorbent assay for one or more of the identified enterotoxins. Staphylococcal enterotoxin D (SED) was produced by 23 (88.5%) strains, SED and SEA were produced in two strains, and SED and SEC were produced in one strain. One strain produced only SEA, and two strains produced only SEC.     

VISA and hetero-VISA among Staphylococcus aureus strains isolated from clinical cases

The VISA (vancomycin intermediate Staphylococcus aureus) and hetero-VISA strains were found among all isolates of S. aureus obtained in the years 1997-2000. The frequency of VISA was 0.3% and h-VISA was about 3%. Most but not all of the h-VISA and all VISA strains were methicillin resistant. Moreover the usefulness of different methods enabling recognition of the h-VISA strains was compared.     

Antiseptic sensitivity of clinical strains of Pseudomonas aeruginosa

MICs, the frequency of clinical and statistic resistance and the antiseptic activity index were studied in complex on out-of-hospital and hospital ecovars of P. aeruginosa. The forms resistant to a number of antiseptics, i.e. chloramine B, chlorhexidine, decamethoxine and dioxidine whose frequency eventually increased were shown to be widely distributed. The antiseptic sensitivity spectrum was more narrow and more heterogeneous than that of other bacteria, the heterogeneity level being dependent on the antiseptic type and bacterial ecovar. The activity of pervomur, phenol, resorcin and boric acid was higher against the clinical strains of P. aeruginosa while iodopyrin, sulfacetamide sodium and dioxidine were less active. The P. aeruginosa strains had natural resistance to cetylpyridinium chloride, rokkal, ethonium, sodium laurate and laurylsulfate and rivanol. It was recommended to assay antiseptic sensitivity of agents causing purulent inflammatory infections and to control circulation of antiseptic resistant variants of bacteria in hospitals.     

Current trends of antibiotic resistance in clinical isolates of Staphylococcus aureus

Staphyloccus aureus （S. aureus） is a well known human pathogen known to causes a verity of infections in humans. In recent years S. aureus is reported to show drug resistant toward commonly known drugs. Therefore, this study was designed to study the pattern of antibiotic resistance in 50 clinical isolates ofS. aureus isolated at Dhanwantri Hospital and Research Centre, Jaipur, Rajasthan, India. S. aureus cultures were isolated from different clinical samples, pus, throat swabs and urine on Blood agar and MacConkey agar and Chrom agar plats and characterized by an array of microscopic and biochemical tests. Antibiotic sensitivity test was performed by standard disc diffusion method （Kirby bayer＇s method） on Muller Hinton agar plates. During this study, among 50 S. aureus isolates 48 （96%） were found to be resistance toward Aztreonam and Doxicycline followed by Ciprofloxacin （n = 45, 90%）, Cefpodoxime and Ceftazidime （n = 44, 88%）, Cefuroxime （n = 40, 80%）, Pipracillin ＋ Tazobactum （n = 38, 76%）, Cefoparazone （n = 36, 72%）, Amoxicillin ＋ Clavulanic acid and Ceftriaxone （n = 33, 66%）, Levofloxacin （n = 32, 64%）, Moxifloxacin （n = 31, 62%）, Ofloaxacin （n = 25, 50%）, Cloxacillin （n = 22, 44%）, Azithromycin （n = 21, 42%）, Clindamycin （n = 19, 38%）, Meropenem （n = 18, 36%）, Clarithromycin （n = 16, 32%）, Ampicillin ＋ sulbactam （n = 13, 26%）, Amikacin （n = 12, 24%）, Impipenem （n = 8, 16%）, Linezolid and Methicillin （n = 7, 14%） and Teicoplanin （n = 3, 6%）. In conclusion, the isolated S. aureus found to be resistant toward common antibiotics, however all isolates were found to be susceptible to Vancomycin.     

Antibiotic resistance of Staphylococcus aureus strains isolated in two different Warsaw hospitals]

S. aureus strains isolated in the same period from different specimens obtained from patients of two different hospitals were compared. The significant differences were observed in the frequency of resistance determinants between strains of these hospitals. The most important was the difference in the prevalence of MRSA. In the first hospital the percentage of MRSA was 40% whereas in the second one only 20%. The resistance to the other antibiotics was also compared, and independently from the compared group: MRSA, MSSA or all, the prevalence of resistance determinants was higher in the first hospital than in the second. Although the frequencies of MRSA in both investigated hospitals were relatively high comparing to the other European countries and in the first hospital even alarming, isolated MRSA strains are less resistant to other antibiotics than MRSA in other countries.     

Drug resistance of Staphylococcus aureus strains, isolated from children with intestinal dysbacteriosis

The level of antibiotic-sensitivity of 73 S. aureus strains isolated from children with dysbacteriosis of the large intestine in an outpatient clinic was determined. The isolation rate of polyresistant strains was 44%. Methicillin-resistant S. aureus (MRSA) were isolated from 25 children (34.2%). 60% of MRSA strains could not be typed with the international set of phages. Among the strains capable of being lyzed by the phages the representatives of phage groups 3 and 4 prevailed. All MRSA strains were sensitive to vancomycin, 84-88% of the strains were sensitive to chloroamphenicol, rifampicin, spiramycin and neomycin, 80% of the strains were sensitive to fusidin and phosphomycin. The level of sensitivity of methicillin-sensitive S. aureus strains (MSSA) to different groups of antistaphylococcal antibiotics was higher. 36-64% of MRSA strains and 21-27% of MSSA strains were resistant to the action of curative bacteriophages. The suppression of obligate microflora was the risk factor in the development of staphylococcal infection of the gastrointestinal tract in children.     

Antimicrobial resistance and toxin gene profiles of Staphylococcus aureus strains from Holstein milk

Isolation of Staphylococcus aureus (Staph. aureus) from Holstein milk samples with mastitis and nonmastitis was conducted to estimate its prevalence, antimicrobial resistance and toxin genes. A total of 353 milk samples were collected from three Chinese Holstein herds. Fifty‐three Staph. aureus isolates collected from 29 Staph. aureus‐positive samples were characterized via antimicrobial susceptibility, toxin genes and Pulsed‐field Gel Electrophoresis (PFGE) profiles. The prevalence of Staph. aureus was 4·0–9·5% in mastitic and 7·3–11·5% in nonmastitic samples in the analysed herds. Approximately 61·0% of Staph. aureus strains isolated from mastitis cows were resistant to ≥10 antimicrobials compared with 0% of isolates with nonmastitis. The most frequently observed super antigenic toxin gene was pvl (41·5%) followed by seh + pvl (13·2%). We did not find mecA‐positive methicillin‐resistant Staph. aureus (MRSA) strains, while mecA‐negative MRSA strains were identified in the three herds. PFGE results suggested potential transmission of Staph. aureus strains in different farms. These results open new insights into Staph. aureus transmission and antimicrobial resistance of Holstein dairy cows and into developing strategies for udder health improvement of dairy cattle.