外科病房2651例院内感染的病原菌构成及耐药情况分析

目的 探讨我院外科住院患者医院感染的病原菌构成种类及耐药情况、敏感药物,为降低医院感染的发生率提供依据,指导临床合理用药.方法 按常规方法对2007-2009年送检2651份标本进行细菌培养、分离、鏊定和药敏试验.进行统计学分析.结果 2651例患者分离培养出病原菌2812株,大肠埃希菌及铜绿假单胞菌二者占半敷以上,为主要致病菌;产β-内酰胺酶菌株大肠埃希菌占78.16%,反映出大多数菌株为耐药菌株的临床情况;铜绿假单胞菌及金黄色葡萄球菌对常用抗生素100%耐药,对亚胺培南、呋喃妥因、万古霉素等较敏感.结论 常见外科住院患者易感染细菌仍为常见大肠埃希菌、铜绿假单胞菌、金黄色葡萄球菌、肺炎克雷伯菌等,普通抗生素已不能达到治疗效果,临床应根据药敏试验结果合理使用抗生素,减少外科医院感染的发生和耐药菌株的产生.     

外科病房2651例院内感染的病原菌构成及耐药情况分析

目的探讨我院外科住院患者医院感染的病原菌构成种类及耐药情况、敏感药物,为降低医院感染的发生率提供依据,指导临床合理用药。方法按常规方法对2007-2009年送检2651份标本进行细菌培养、分离、鉴定和药敏试验,进行统计学分析。结果 2651例患者分离培养出病原菌2812株,大肠埃希菌及铜绿假单胞菌二者占半数以上,为主要致病菌;产β-内酰胺酶菌株大肠埃希菌占78.16%,反映出大多数菌株为耐药菌株的临床情况;铜绿假单胞菌及金黄色葡萄球菌对常用抗生素100%耐药,对亚胺培南、呋喃妥因、万古霉素等较敏感。结论常见外科住院患者易感染细菌仍为常见大肠埃希菌、铜绿假单胞菌、金黄色葡萄球菌、肺炎克雷伯菌等,普通抗生素已不能达到治疗效果,临床应根据药敏试验结果合理使用抗生素,减少外科医院感染的发生和耐药菌株的产生。     

儿童呼吸内科下呼吸道分离菌分布及药敏分析

目的 分析我院儿童呼吸内科下呼吸道标本分离菌的分布及其耐药情况,为临床治疗用药提供参考。方法 对我院2016年7月~2018年6月呼吸内科送检的4137例下呼吸道标本分离菌进行收集,并进行药敏试验。结果 4317例送检标本中共分离出2060株（去除重复菌株）,其中革兰阴性菌1437株,占69.75%;革兰阳性菌623株,占30.25%。排前五的分离菌依次为流感嗜血杆菌（41.02%）、肺炎链球菌（21.17%）、卡他莫拉菌（19.03%）、金黄色葡萄球菌（8.98%）、肺炎克雷伯菌（3.83%）。流感嗜血杆菌、卡他莫拉菌对头孢噻肟、利福平、氧费沙星全部敏感;对氨苄西林、复方新诺明敏感性低。肺炎链球菌、金黄色葡萄球菌对利奈唑胺、万古霉素全部敏感;对红霉素敏感性低。结论 儿童下呼吸道病原菌种类多样,主要为革兰阴性菌,应依据病原菌的种类及药敏特点选择有针对性的高效抗菌药物,制定个体化治疗方案,减少耐药菌株的产生。     

2016年某院金黄色葡萄球菌感染分布及耐药性分析

目的 对2016年秦皇岛市第一医院患者金黄色葡萄球菌感染情况及耐药特点进行调查,为感染监控和临床用药提供参考.方法 回顾性分析2016年住院患者细菌培养标本中金黄色葡萄球菌的分离情况及耐药性.结果 共分离金黄色葡萄球菌311株,其中耐甲氧西林金黄色葡萄球菌(MRSA) 108株,占34.7％.金黄色葡萄球菌感染的标本来源主要有痰液(46.95％)、分泌物(34.73％)和全血(9.64％);感染科室主要以重症监护室、神经外科、儿科、老年病科、骨科多见.药物敏感性试验结果显示,MRSA耐药率明显高于甲氧西林敏感金黄色葡萄球菌(MSSA),未发现对万古霉素、替加环素耐药的菌株,对利奈唑胺和喹努普汀/达福普汀、呋喃妥因的敏感率也很高,但对克林霉素、红霉素耐药率达70％以上,而对青霉素的耐药率高达97.1％.结论 甲氧西林敏感金黄色葡萄球菌(MSSA)对部分抗菌药物仍保持较好的敏感性,而MRSA表现为多重药耐药性,应引起临床高度重视,临床应根据药物敏感性试验结果合理使用抗菌药物.     

2000年～2002年我院常见细菌的分离率与耐药监测

目的 :了解 2 0 0 0～ 2 0 0 2年常见菌的分布与耐药状况。方法 :采用上海新和公司实验室信息管理系统软件对分离的菌株和药敏试验结果进行分析。结果 :大肠埃希菌 ,铜绿假单胞菌 ,不动杆菌 ,肺炎克雷伯菌 ,金黄色葡萄球菌分离率占前五位 ,且有逐年增加趋势。大肠埃希菌对亚胺培南 ,头孢西丁 ,头孢他啶的耐药率在 30 %以下 ,铜绿假单胞菌对哌拉西林、头孢他啶、头孢吡肟、阿米卡星的耐药率在 30 %以下 ,不动杆菌对亚胺培南的耐药率低于 1 1 % ,其余抗生素耐药率均高于 30 % ;金黄色葡萄球菌对复方新诺明的耐药率在 1 0 %以下 ,对万古霉素耐…     

2022年北京航天总医院细菌耐药性监测

目的 监测2022年北京航天总医院临床分离到的菌株对抗菌药物的耐药性。方法 采用自动化鉴定及药敏仪器对从临床样本培养分离到的细菌菌株进行体外抗菌药物敏感性试验,参照2021年美国临床和实验室标准化协会(CLSI)推荐的药敏试验方法标准判读结果,用WHONET 5.6软件进行数据统计分析。结果 2022年临床分离细菌共3 261株,分离自呼吸道标本最多,占60.07%。其中革兰阳性菌982株,约占30.11%,葡萄球菌属544株,占革兰阳性菌的55.40%,肠球菌属338株,占革兰阳性菌34.42%,链球菌属31株。革兰阴性菌共2 279株,占69.89%,其中肠杆菌属1 222株,占革兰阴性菌的53.62%,非发酵菌1 017株,占革兰阴性菌的44.62%。分离率前5名的菌株依次为肺炎克雷伯菌、铜绿假单胞菌、大肠埃希菌、鲍曼不动杆菌、屎肠球菌。耐甲氧西林金黄色葡萄球菌(MRSA)的检出率为22.86%,耐甲氧西林凝固酶阴性葡萄球菌(MRCNS)的检出率为75.07%,未发现万古霉素耐药的葡萄球菌。肺炎克雷伯菌对亚胺培南和美岁培南的耐药率分别为42.9%和67.0%,大肠埃希菌对亚胺培南...     

某儿童医院术后切口感染病原菌及耐药性分析

目的分析儿童医院外科手术后切口感染病原菌及耐药性情况,为预防和治疗术后感染提供科学依据。方法收集海南省妇女儿童医学中心外科手术后创口分泌物及脓液送检标本,采用VITEK 2 Compact全自动微生物药敏分析仪进行细菌培养鉴定和药敏试验,采用WHONET 5.6软件进行统计学分析。结果 292例外科手术后切口感染患者的创口分泌物和脓液标本中共分离出169株病原菌,其中革兰氏染色阳性球菌占59.2%,主要为金黄色葡萄球菌;革兰氏染色阴性杆菌占33.7%,主要为大肠埃希菌、肺炎克雷伯菌、铜绿假单胞菌、鲍曼不动杆菌;真菌占7.1%,主要为白色念珠菌。药敏结果方面,金黄色葡萄球菌多重耐药以苯唑西林敏感性实验作为标准,耐药率为48.3%,革兰氏染色阴性杆菌中大肠埃希菌对β-内酰胺类抗生素的耐药性略高,肺炎克雷伯菌对β-内酰胺类抗生素有较高的耐药性,铜绿假单胞菌和鲍曼不动杆菌对各类抗生素都较敏感。结论外科手术后切口感染以金黄色葡萄球菌、大肠埃希菌、肺炎克雷伯菌为主,细菌耐药情况仍然比较严峻,合理的术前准备工作和有效的使用抗菌药物治疗尤为重要,应尽量减少或避免经验用药,同时应当加强抗生素使用的监管,杜绝滥用,以减少耐药菌株的产生。     

口咽部正常菌群对肺炎支原体快速培养法试剂盒的影响

目的 观察常见的口咽部正常菌群对肺炎支原体快速培养法试剂盒结果的影响,评价其临床实用性和可靠性。方法 用标准菌株和口咽部分离的临床菌株作为研究对象,观察不同细菌对培养结果的影响。结果 标准菌株肺炎链球菌、金黄色葡萄球菌、流感嗜血杆菌、大肠埃希菌、白念珠菌在试剂盒中的培养阳性率分别为0,10.00%,10.00%,10.00%,20.00%,临床分离的野生型和耐药型草绿色链球菌培养阳性率分别为5.00%,80.00%;表皮葡萄球菌为15.00%,90.00%;肺炎克雷伯菌为25.00%,80.00%,白念珠菌为20.00%,85.00%;鲍曼不动杆菌为90.00%,100.00%。除鲍曼不动杆菌外其它四种耐药型菌株的培养阳性率明显增高。结论 口咽部若存在耐药菌或多重耐药菌以及对某些抗生素有天然耐药机制的细菌时会造成肺炎支原体快速培养法检测结果出现假阳性,在试验结果报告中应注意其假阳性的问题。     

临床分离的4379株病原菌的分布特征及药敏结果分析

目的了解本院2008年临床分离的病原菌的分布特征及药敏结果,为合理使用抗菌药物提供依据。方法大多数细菌鉴定和药敏试验利用BD Phoenix仪,少数利用手工鉴定和K-B法药敏试验。念珠菌利用显色平板分离和鉴定,K-B法进行药敏试验。结果4379株细菌念珠菌中最常见的为大肠埃希菌（10.2%）、铜绿假单胞菌（9.4%）、金黄色葡萄球菌（7.7%）、鲍曼不动杆菌（7.7%）、白色念珠菌（7.0%）和肺炎克雷伯菌（6.2%）。大肠埃希菌和肺炎克雷伯菌产ESBLs比例分别为47.8%和41.3%。金黄色葡萄球菌、表皮葡萄球菌、溶血葡萄球菌和腐生葡萄球菌甲氧西林耐药率分别为58.1%、82.8%、83.6%和73.1%。G-杆菌中耐药率较低的为头孢哌酮/舒巴坦、亚胺培南、哌拉西林-他唑巴坦和阿米卡星。G＋球菌,万古霉素和替考拉宁的敏感率均为100.0%,其他抗菌药物耐药率较低的为氯霉素。念珠菌对两性霉素B和制霉菌素的耐药率均低于2.0%。结论本院临床分离大肠埃希菌和肺炎克雷伯菌产ESBLs水平、非发酵G-杆菌碳青霉烯类耐药率和葡萄球菌甲氧西林耐药率居高不下,应加强抗菌药物的合理使用,以降低耐药率。     

南京市江宁医院2015年~2017年血培养阳性病原菌分布及耐药性分析

目的 研究血培养阳性检出的病原菌分布及耐药情况,指导临床合理用药。方法 采用法国梅里埃公司Bact/Alert 3D全自动血培养仪对我院2015年1月~2017年12月送检的血培养标本进行培养,阳性标本用VITEK 2 Compact全自动细菌鉴定及药敏分析系统进行细菌鉴定和药敏试验,观察病原菌分布及耐药情况。结果 共分离出病原菌459株,检出率为9.57%,其中革兰阴性杆菌246株（53.59%）,革兰阳性球菌202株（44.01%）,真菌11株（2.40%）;前3位病原菌依次为大肠埃希菌、肺炎克雷伯菌、金黄色葡萄球菌。大肠埃希菌对美罗培南、阿米卡星、厄他培南、亚胺培南均较敏感,耐药率低于3%。肺炎克雷伯菌对美罗培南、阿米卡星、厄他培南、亚胺培南、头孢替坦较敏感,耐药率低于6%。未检出对万古霉素、利奈唑胺、喹努普汀/达福普汀、替加环素耐药的金黄色葡萄球菌。结论 本院血培养的病原菌种类多,以革兰阴性杆菌为主,且耐药情况复杂。应加强对病原菌的鉴定和药敏监测,指导临床合理用药,防止广谱抗生素的滥用,减少耐药菌株的产生。     

Cell wall thickening is a common feature of vancomycin resistance in Staphylococcus aureus

We have previously shown that a thickened cell wall is responsible for the vancomycin resistance of vancomycin-resistant Staphylococcus aureus (VRSA) (equivalent to vancomycin-intermediate S. aureus and glycopeptide-intermediate S. aureus) strain Mu50 (L. Cui, H. Murakami, K. Kuwahara-Arai, H. Hanaki, and K. Hiramatsu, Antimicrob. Agents Chemother. 44:2276-2285, 2000). However, the mechanism of vancomycin resistance in other VRSA strains remained unclear. In this study, 16 clinical VRSA strains from seven countries were subjected to serial daily passage in drug-free medium. After 10 to 84 days of passage in the nonselective medium, passage-derived strains with decreased MICs of vancomycin (MIC, <4 mg/liter) were obtained. However, all of the passage-derived strains except one (15 of 16) still possessed subpopulations that were resistant to vancomycin as judged by population analysis, and vancomycin-resistant mutant strains were selected from the passage-derived strains by one-step vancomycin selection with a frequency of 4.25 x 10(-6) to 1.64 x 10(-3). The data indicated that vancomycin-resistant cells are frequently generated from the passage-derived strains even after vancomycin selective pressure is lifted. Cell wall thicknesses and MICs of glycopeptides (vancomycin and teicoplanin) and beta-lactams (imipenem and oxacillin) were determined for a total of 48 strains, including 15 sets of three strains: the clinical VRSA strain, the passage-derived strain, and the vancomycin-resistant mutant strain obtained from the passage-derived strain. No simple correlation between glycopeptide and beta-lactam MICs was seen, while significant correlations between MICs of vancomycin and teicoplanin (r = 0.679; P < 0.001) and between MICs of imipenem and oxacillin (r = 0.787; P < 0.001) were recognized. Moreover, all of the VRSA strains had significantly thickened cell walls, which became thinner with the loss of vancomycin resistance during drug-free passages and again became thick in the resistant mutant strains. The data showed that cell wall thickness had high correlation with the MICs of the two glycopeptides (correlation coefficients, 0.908 for vancomycin and 0.655 for teicoplanin) but not with those of the beta-lactam antibiotics tested. These results together with coupled changes of cell wall thickness and vancomycin MICs in 16 isogenic sets of strains indicate that thickening of the cell wall is a common phenotype of clinical VRSA strains and may be a phenotypic determinant for vancomycin resistance in S. aureus.     

In vitro activities of eight antibiotics against methicillin-resistant S. aureus and S. epidermidis strains isolated in Korea

Staphylococcus aureus and Staphylococcus epidermidis strains isolated at eight large medical centers in Korea were examined for methicillin resistance and resistance to eight other antibiotics; cefazolin, cefamandole, cefuroxime, cefoxitin, cefotaxime, moxalactam, penicillin G and vancomycin. Methicillin resistance was found in 296 of 1225 strains (24.2%) of S. aureus and 126 of 348 strains (36.2%) of S. epidermidis. Methicillinresistant strains were isolated from all sources with the frequency of isolation ranging from 11% to 60%. From pleural effusion, throat swab and blood, methicillin-resistant strains of S. aureus were more frequently isolated with statistical significance (Chi-squared test, 95% confidence). Almost all of Methicillin-resistant S. aureus (MRSA) and S. epidermidis (MRSE) strains were multiply resistant to one or more tested eight antibiotics. However only 7(2.4%) of 296 MRSA strains and 2(1.6%) of 126 MRSE strains were resistant to vancomycin. Vancomycin was the most effective antibiotic against staphylococcal isolates as well as MRSA and MRSE.     

Detection of vancomycin resistant Staphylococcus aureus: a comparative study of three different phenotypic screening methods

The objective of this study was to investigate screening methodologies, to detect Staphylococcus aureus strains with decreased susceptibility to vancomycin. Three methods were used to screen 160 Staphylococcus aureus clinical isolates along with ATCC quality control strains. Subsequently, MIC of all these 160 strains were determined by NCCLS methodology. The MIC of all the 160 clinical isolates was < or = 4 microg/mL and were classified as vancomycin susceptible by NCCLS criteria but 23 strains were positive by Hiramatshu method, two grew on MHA (5 microg/mL vancomycin) while CDC method correctly identified no vancomycin intermediate S.aureus (VISA) or vancomycin resistant S.aureus (VRSA) strains with reference to there MIC. CDC method was found to be the most appropriate screening methodology for detection of VISA or VRSA for diagnostic laboratories.     

Emergence of low level vancomycin resistance in MRSA

One hundred and twenty methicillin resistant Staphylococcus aureus (MRSA) strains were checked for minimum inhibitory concenteration (MIC) of vancomycin. The results showed that 98 strains (81.7 %) had MIC < 4microg/mL, 18 strains (15 %) had MIC 8 microg/mL, and 4 (03.3%) had MIC 16 microg/mL which being borderline between sensitive (< 4microg/mL) and resistant (>32 microg/mL) values points towards possible emergence of low level vancomycin resistance in the organisms and may explain the reasons of delayed therapeutic success of vancomycin in S. aureus bacteraemia in some situations.     

Molecular epidemiology of methicillin-resistant Staphylococcus aureus bloodstream isolates in urban Detroit

To gain a better understanding of epidemiology of resistance in Staphylococcus aureus, we describe the molecular epidemiology of methicillin-resistant Staphylococcus aureus bloodstream isolates in urban Detroit. Bloodstream isolates from July 2005 to February 2007 were characterized. Two hundred ten bloodstream isolates from 201 patients were evaluated. Patient characteristics were as follows: median age, 54 years; 56% male; and 71% African-American. Seventy-six percent of infections were health care associated, with 55% being community-onset infections and 21% hospital acquired, and 24% were community associated. The most common sources were skin/wound (25%), central venous catheters (24%), unknown source (20%), and endocarditis (9%). Ninety percent and 5% of isolates had a MIC of vancomycin of or=1.5 mg/liter. Results of pulsed-field gel electrophoresis showed 17 strain types. The predominant strains were USA100 (104 isolates) and USA300 (74 isolates). Forty-nine percent of the isolates had staphylococcal cassette chromosome mec II, and 56% had agr II. All USA300 isolates were positive for the Panton-Valentine leukocidin toxin genes and agr I. Forty-seven percent of USA300 bloodstream infections were health care associated (35% community onset and 12% hospital onset). USA300 strains were more common in injection drug users with skin/wound as the predominant source of infection. Thirty percent of the USA100 strains were closely related to vancomycin-resistant Staphylococcus aureus isolates. The results of this study show that vancomycin MICs using automated dilution testing with Vitek-2 and E-test were highly discordant. Most methicillin-resistant S. aureus strains causing bacteremia are health care associated, commonly have MICs of vancomycin that are high within the susceptible range are not detected by routine automated dilution testing, and have significant diversity of molecular characteristics. USA100 strains that are closely related to vancomycin-resistant S. aureus (VRSA) isolates and USA300 strains are common as causes of both hospital and community-onset infection. Infection control measures should focus not only on prevention of the spread of community strains in the hospital but also prevention of the spread of hospital strains associated with VRSA into the community.     

Genetic background and antibiotic resistance of Staphylococcus aureus strains isolated in the Republic of Georgia

The genetic composition and antibiotic sensitivities of 50 clinical isolates of Staphylococcus aureus obtained from various clinics in the Republic of Georgia were characterized. S. aureus strains ATCC 700699 and ATCC 29737 were included as reference standards in all analyses. All 52 strains had identical 16S rRNA profiles. In contrast, pulsed-field gel electrophoresis (PFGE) identified 20 distinct PFGE types among the 52 strains examined, which indicates that PFGE is more discriminating than is 16S rRNA sequence analysis for differentiating S. aureus strains. The results of our PFGE typing also suggest that multiple genetic subpopulations (related at the ca. 85% similarity level, based on their SmaI PFGE patterns) exist among the Georgian S. aureus strains. Twenty-two of the 50 Georgian strains were methicillin resistant and PCR positive for mecA, and 5 strains were methicillin sensitive even though they possessed mecA. None of the strains were vancomycin resistant or contained vanA. The nucleotide sequences of mecA fragments obtained from all mecA-containing strains were identical. Our data indicate that the population of S. aureus strains in Georgia is fairly homogeneous and that the prevalence of methicillin-resistant, mecA-positive strains is relatively high in that country.     

Prevalence of methicillin resistant Staphylococcus aureus in a tertiary referral hospital in eastern Uttar Pradesh

We report the prevalence of methicillin resistant Staphylococcus aureus (MRSA) infections and their antibiotic susceptibility pattern in our hospital located in eastern Uttar Pradesh. Out of total 549 strains of Staphylococcus aureus isolated from different clinical specimens 301 (54.85%) were found to be methicillin resistant. More than 80% of MRSA were found to be resistant to penicillin, cotrimoxazole, ciprofloxacin, gentamicin, erythromycin, tetracycline, 60.5% to amikacin and 47.5% to netilmicin. However, no strains were resistant to vancomycin. Many MRSA strains (32.0%) were multi-drug resistant. To reduce the prevalence of MRSA, the regular surveillance of hospital associated infection, monitoring of antibiotic sensitivity pattern and formulation of definite antibiotic policy may be helpful.     

Rapid identification of fibronectin, vitronectin, laminin, and collagen cell surface binding proteins on coagulase-negative staphylococci by particle agglutination assays.

Seventeen strains of ten different species of coagulase-negative staphylococci were shown to interact with collagen, laminin, fibronectin, and vitronectin immobilized on latex beads. Different species of coagulase-negative staphylococci have different capacities to agglutinate proteins. Cells of 18 strains of Staphylococcus haemolyticus reacted more strongly than did cells of 18 Staphylococcus epidermidis strains with proteincoated latex beads, although no significant difference in cell surface hydrophobicity or charge could be shown. The cell surface receptors of S. haemolyticus were more heat and protease resistant than were Staphylococcus aureus receptors. Strains of Staphylococcus saprophyticus isolated from urinary tract infections showed a high capacity to adhere to laminin. The ability to agglutinate fibronectin and collagen was common among coagulase-negative staphylococci isolated from other infections; 55% (31 of 56) and 63% (35 of 56) agglutinated fibronectin and/or collagen. S. haemolyticus and S. epidermidis bound to both N-terminal (29-kDa) and C-terminal (120-kDa) fragments of fibronectin.     

An evaluation of three rapid coagglutination tests: Sero-STAT, Accu-Staph, and Staphyloslide, for differentiating Staphylococcus aureus from other species of staphylococci

Three commercial coagglutination tests--Sero-STAT, Accu-Staph, and Staphyloslide--were performed in parallel with slide coagulase, tube coagulase, and thermostable nuclease tests on 100 methicillin-susceptible Staphylococcus aureus (MSS) strains, 100 methicillin-resistant S. aureus (MRS) strains, and 100 non-S. aureus staphylococcal strains (NSA). All three coagglutination tests showed sensitivities of 100% for MSS strains. For MRS strains, sensitivities were, respectively, 99%, 100%, and 99%. False-positive reactions were, respectively, 10%, 2%, and 2%. A marked difference in slide coagulase test sensitivity was found for MSS strains (79%) and MRS strains (14%). These findings suggest that the coagglutination tests may be less sensitive for detecting MRS strains than for detecting MSS strains and that these properties may be related to clumping factor reactivity. The high false-positive rate for Sero-STAT and even the 2% false-positive rate for Accu-Staph and Staphyloslide make clinical usefulness at this time somewhat problematic and debatable. In view of these findings, the authors prefer to retain the tube coagulase test and thermostable nuclease test for differentiation of S. aureus from non-S. aureus strains in their laboratory.     

Peptidoglycan modification of Staphylococcus aureus P18 strain after use of 6 active antibiotics on the bacterial wall

Six antibiotics active on the cell-wall were tested against a methicillin resistant Staphylococcus aureus P18 strain at the start of exponential growth rate. The concentration was four-fold the MIC determined in a non-hypersaline liquid medium. The peptidoglycan amino-acid content of the various cell wall samples was determined. An antibiotic-free S. aureus P18 and the methicillin-sensitive Cowan I. S. aureus strain were used a controls. Beta lactam antibiotic treatment, oxacillin and cephalothin, induced an increase of alanine content which suggests that only secondary-transpeptidation did not occur. Similar results were obtained using vancomycin. Amino-acid content was not modified by bacitracin, which is in agreement with the results expected. The results obtained for fosfomycin and cefamandole were not easy to interpret.