Antibacterial Activity of a Biphenyl and Xanthones from Kielmeyera coriacea

The in vitro antibacterial activities of the biphenyl aucuparin and xanthones, obtained from the dichloromethane extract of the leaves of Kielmeyera coriacea (Guttiferae) were tested against Gram-positive and Gram-negative bacteria. In addition, time-kill studies were performed to determine if aucuparin had bactericidal activity. It is not known whether the aucuparin found in K. coriaceae is due to de novo synthesis in response to diverse forms of stress, is already present in the plant, or is a combination of both. Aucuparin and 1,3,7- trihydroxy-2-(3-methylbut-2-enyl)-xanthone showed antimicrobial activities against Bacillus subtilis with MIC values of 3.12µg/ml and 12.5µg/ml, respectively, and aucuparin against Staphylococcus aureus with a MIC value of 12.5µg/ml. In contrast to the relatively low MICs for Grampositive bacteria, Gram-negative bacteria tested were not inhibited by aucuparin at concentrations =100µg/ml. The kinetics of bactericidal activity were evaluated against S. aureus at six concentrations of aucuparin (0.25×, 0.5×, 1×, 2×, 4× and 8× the MIC). The rate of bacterial killing was dependent on the concentration of aucuparin, with more than 10 5 organisms/ml being eradicated within 8 h at the highest concentration studied. Bacterial culture was monitored for up to 24 h, and no regrowth was observed.     

Synthesis and in vitro antibacterial activity of some N-(5-aryl-1,3,4-thiadiazole-2-yl)piperazinyl quinolone derivatives

A series of N-[5-(1-methyl-5-nitro-2-imidazolyl)-1,3,4-thiadiazole-2-yl] and N-[5-(nitrophenyl)-1,3,4-thiadiazole-2-yl] piperazinyl quinolone derivatives (5a-c and 5d-l) were synthesized and evaluated for in vitro antibacterial activity against some Gram-positive and Gram-negative bacteria. The antibacterial data revealed that all nitroimidazole derivatives (5a-c) showed interesting activity against tested Gram-positive bacteria (minimum inhibitory concentration, MIC=0.008-0.03 microg/ml) while they did not show good activity against Gram-negative organisms. Despite the significant activity of nitroimidazole series, all nitrophenyl analogues (5d-l) were inactive against both Gram-positive and Gram-negative bacteria. Among all of the tested compounds, 5a (ciprofloxacin derivative in nitroimidazole series) exhibited excellent activity against Staphylococcus aureus and Staphylococcus epidermidis (MIC=0.008 microg/ml).     

Synthesis and antimicrobial activity of some novel 2-(p-substituted-phenyl)-5-substituted-carbonylaminobenzoxazoles

A series of 2-(p-substituted-phenyl)-5-substituted-carbonylamino benzoxazole derivatives (5-22) was synthesized and their antimicrobial activities determined in comparison to several control drugs. The synthesized compounds were tested in vitro against Staphylococcus aureus, Streptococcus faecalis and Bacillus subtilis as Gram-positive, Pseudomonas aeruginosa and Escherichia coli as Gram-negative bacteria and the yeast Candida albicans. Microbiological results showed that the compounds possessed a diffuse spectrum of antibacterial activity against these microorganisms. Compound 9 which bears a phenylacetamido moiety at position 5 and a 4-fluorophenyl group at the 2-position of benzoxazole ring was the most active derivative against S. aureus, S. faecalis and P. aeruginosa with a MIC value of 12.5 microg/ml. Compound 11 provided higher potency than the other tested compounds against B. subtilis at a MIC value of 12.5 microg/ml. Compounds 5-22 showed antifungal activity against C. albicans with MIC values between 50 and 12.5 microg/ml.     

余甘子醇提物不同萃取部位对人消化道常见菌的抑制作用研究

目的:研究余甘子醇提物4种不同萃取部位对人消化道常见菌的抑制作用。方法:采用管碟法进行余甘子醇提物及醇提物中石油醚、乙酸乙酯、三氯甲烷、水部位对大肠杆菌的抑菌试验,测量其抑菌圈直径以确定最佳抑菌部位,二倍稀释法测定最低抑菌浓度(MIC)。采用宏量肉汤稀释法(试管法)进行余甘子醇提物最佳抑菌部位对消化道菌群的抑菌试验,测定其MIC。结果:余甘子醇提物对大肠杆菌的MIC为0.625 mg/ml。余甘子醇提物乙酸乙酯部位为最佳抑菌部位,其对金黄色葡萄球菌、表皮葡萄球菌、枯草芽孢杆菌、白色念珠菌、变形杆菌、沙门氏菌的MIC均为2.5 mg/ml,对肺炎链球菌的MIC为0.625 mg/ml,对大肠杆菌和产气荚膜杆菌的MIC均为1.25 mg/ml,对破伤风杆菌的MIC为0.156 mg/ml。结论:余甘子醇提物乙酸乙酯部位对消化道常见菌群有较强的抑制作用。     

3,4,5,3',5'-Pentabromo-2-(2'-hydroxybenzoyl)pyrrole: a potential lead compound as anti-Gram-positive and anti-biofilm agent

The activity against Gram-positive bacteria of 3,4,5,3',5'-pentabromo-2-(2'-hydroxybenzoyl)pyrrole I, a synthetic anti-bacterial compound related to pyrrolomycins, was tested in vitro using seven reference bacterial strains and Staphylococcus epidermidis and Staphylococcus aureus preformed biofilms. Compound I was active against all strains tested, with minimum inhibitory concentration (MIC) values ranging from 0.002 to 0.097 mg/l and minimum bactericidal concentrations (MBCs) from 0.37 to 12.5 mg/l. Compound I was also active at low concentrations against preformed S. epidermidis and S. aureus biofilms.     

Synthesis and in-vitro antibacterial activity of 5-substituted 1-methyl-4-nitro-1H-imidazoles

A series of 5-substituted 1-methyl-4-nitro-1H-imidazole derivatives were synthesized and evaluated for in-vitro antibacterial activity against a panel of microorganisms including Staphylococcus aureus, Staphylococcus epidermidis, Bacillus subtilis, Escherichia coli, Klebsiella pneumonia, Enterobacter aerogenes, and Helicobacter pylori using conventional agar dilution method. Among the test compounds, 1-methyl-4-nitro-5-(phenylsulfonyl)-1H-imidazole was the most potent against Gram-positive bacteria, with a MIC value of < or =8 microg/mL. All compounds showed no significant activity against Gram-negative bacteria at concentrations < or =64 microg/mL. The MIC values against 15 clinical isolates of H. pylori indicated that compounds 10 and 11 were the most active compounds in this series in terms of inhibiting the growth of H. pylori (MIC = 2 microg/mL). It was also demonstrated that their corresponding activities were four times larger than that of metronidazole.     

具有手性吡咯烷侧环的噁唑烷酮类化合物的合成及抗菌活性研究

目的 设计合成具有手性吡咯烷侧环的噁唑烷酮类化合物,并考察其体外抗菌活性。方法 以手性脯氨酸和3,4-二氟硝基苯为原料,通过多步反应合成目标化合物;采用微量液体稀释法检测目标化合物的抗菌活性。结果与结论 合成了 8 个新化合物,其结构经 ¹H-NMR、MS 谱确证。体外活性试验表明：由（R）-脯氨酸衍生的化合物7b 对革兰阳性菌[金黄色葡萄球菌、表皮葡萄球菌以及耐甲氧西林金黄色葡萄球菌（MRSA）具有良好的抑制活性,对革兰阴性菌具有较弱的抑制活性。由（S）-脯氨酸衍生的化合物 7a 的抗菌活性明显低于 7b。研究结果表明,吡咯烷侧环的手性因素对抗菌活性具有显著影响。     

PD-140248 (Parke-Davis & Co)

PD-140248 is an isomerase inhibitor and topoisomerase II inhibitor under development by Parke-Davis and Co as a potential treatment for bacterial infection. Although no details of active development have been published in the scientific literature since 1996, in September 1999, the company confirmed that PD-140248 is still in active development [338530]. The compound is one of two new pyrrolidinyl naphthyridines (the other compound being PD-131628) with a broad spectrum of antibacterial activity, including activity against quinolone-resistant bacteria. PD-140248 demonstrates strong in vitro activity, particularly against Gram-positive bacteria, such as quinolone-susceptible Staphylococcus aureus (S aureus), Staphylococcus epidermidis (S epidermidis), Staphylococcus haemolyticus (S haemolyticus), methicillin- and ciprofloxacin-resistant S aureus, Streptococcus species, Streptococcus pneumoniae (S pneumoniae) and Enterococcus faecalis (E faecalis). An MIC90 value of 0.015 microg/ml was obtained against Haemophilus influenzae (H influenzae) and Moraxella catarrhalis [160129]. The (3R,1S) enantiomer, PD-140248, demonstrated a 1- to 10-fold enhanced activity against Gram-positive and Gram-negative organisms in vitro and in vivo compared to its stereoisomers, and has thus been targeted for further preclinical studies [133377].     

Antimicrobial activity and chemical composition of the essential oil of Hofmeisteria schaffneri

Objectives The aims of this study were to establish the antimicrobial potential of Hofmeisteria schaffneri essential oil and its chemical composition. Methods The essential oils of Hofmeisteria schaffneri harvested at flowering (batches I and IV) and non‐flowering (batches II and III) seasons were prepared by hydrodistillation and analysed by GC and GC‐MS. The aqueous and organic (CH₂Cl₂‐MeOH 1 : 1) extracts were prepared by using infusion and maceration techniques, respectively. The in‐vitro antimicrobial activity of the preparations and compounds against Candida albicans and some bacteria (Gram‐negative and Gram‐positive) was assessed using the broth dilution method in 96‐microplate wells. Key findings Forty‐four compounds, representing ～90% of the total constituents, were identified in the essential oil of Hofmeisteria schaffneri collected in flowering (batches I and IV) and non‐flowering (batches II and III) seasons. In all cases, several thymol analogues were the major components of the oils (～65%); some small differences in the relative proportions of these constituents were observed. The infusion exhibited an antibacterial activity against Staphylococcus aureus and Bacillus subtilis, with a MIC value of 64 µg/ml in each case. The essential oil batches were active against Staphylococcus aureus, with MIC ranging from 48 to 192 µg/ml. They were, however, inactive against Gram‐negative bacteria, including Pseudomonas aeruginosa, Escherichia coli and Salmonella typhi (MIC > 1024 µg/ml). On the other hand, the infusion of the plant as well as the oil from batch I displayed anti‐Candida albicans activity, with MIC of 128 and 192 µg/ml, respectively. Finally, the organic extract did not displayed significant activity against the tested microorganisms (MIC ≥ 1024 µg/ml). Some of the compounds isolated from the plant were also tested. Compounds 8 and 38, which were present in the essential oils, displayed the best antibacterial effect against Gram‐positive bacteria (MIC ranging between 32 and 64 µg/ml). Compounds 6 (present in the infusion) and 10 (present in all preparations) showed higher activity against the yeast (MIC = 128 µg/ml) than the remaining compounds, with MIC values ranging from 256 to 512 µg/ml. Conclusions The composition and antimicrobial activity of the oils changed slightly from flowering to non‐flowering seasons. The results of the present investigation provide in‐vitro scientific support for the use of the plant against skin infections in Mexican folk medicine.     

中药金贯蓝提取物对寻常痤疮相关致病菌的体外抑菌作用

目的 考察自主研发的协定方中药“金贯蓝”提取物对寻常痤疮三种主要致病菌（痤疮丙酸杆菌、表皮葡萄球菌、金黄色葡萄球菌）的体外抑菌效果,为其临床治疗寻常痤疮提供一定实验依据。方法 2021年1月至2022年3月采用琼脂打孔法考察金贯蓝提取物对三种痤疮相关致病菌的抑菌活性,并评估不同浓度药物对上述菌的抗菌作用是否具有浓度相关性;采用倍比稀释法测定药物最低抑菌浓度以及最小杀菌浓度,绘制药物时间抑菌曲线进一步考察其作用特点。结果 500 g/L金贯蓝提取物对C. acnes、S. epidermidis、S. aureus的抑菌圈直径分别为（27.67±2.52）mm、（23.33±1.53）mm、（22.00±1.00）mm;浓度为250 g/L金贯蓝提取物对C. acnes、S. epidermidis、S. aureus的抑菌圈直径分别为（22.33±0.58）mm、（20.67±1.53）mm、（20.11±1.20）mm;浓度为100 g/L金贯蓝提取物对C. acnes、S. epidermidis、S. aureus的抑菌圈直径分别为（13.30±0.75）mm、（10.67±1....     

某三甲医院主要革兰阳性菌临床分布及耐药性分析

目的了解大连市友谊医院2018年常见革兰阳性菌的耐药情况及耐药迁徙率分析。方法收集友谊医院细菌室2018年324株革兰阳性细菌进行菌种鉴定的体外药物敏感性试验。结果 324株革兰阳性细菌中,金黄色葡萄球菌134株(30%),屎肠球菌84株(19%),表皮葡萄球菌61株(14%),粪肠球菌45株(10%),这四种主要细菌占所检出的革兰阳性菌的73%。在细菌的科室分布中,医学重症科内科(16.05%)和泌尿科(16.36%)是检出革兰阳性细菌最多的科室,而标本来源可知尿液(32.1%)和痰液(19.14%)为检出率最高的标本。检出的最主要的四种细菌中,金黄色葡萄球菌、表皮葡萄球菌、粪肠球菌和屎肠球菌对抗生素的耐药种类及相应的耐药率表现出不同的特点。检测的四种主要细菌中,有三种对青霉素有高度耐药性,分别是屎肠球菌(95.2%)、金黄色葡萄球菌(92.5%)和表皮葡萄球菌(90.2%),并且细菌对红霉素耐药性也较高,但耐药率不如青霉素,分别是金黄色葡萄球菌(64.9%)、表皮葡萄球菌(73.8%),粪肠球菌(71.1%)和屎肠球菌(85.7%)。粪肠球菌、金黄色葡萄球菌和表皮葡萄球菌对万古霉素...     

Evaluation of Antibacterial Activities of Medicinal Plants Widely Used Among AIDS Patients in Thailand

Abstract

Antibacterial activity of 12 selected Thai medicinal plants used as self-medication by HIV/AIDS patients in Thailand was studied. Thirty-nine chloroform, methanol, and aqueous extracts from these plants were investigated for their antibacterial activity against important pathogenic bacteria commonly associated with AIDS infection. These included Staphylococcus aureus., methicillin-resistant Staphylococcus aureus. (MRSA), Streptococcus mutans., and Salmonella typhi.. Inhibition of growth was tested using paper disk agar diffusion method. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined by agar microdilution method and agar dilution method in Petri dishes with millipore filters. The Gram-positive bacteria were proved to be susceptible to the chloroform extracts of Alpinia galanga. (L.) Willd., Boesenbergia rotunda. Mansf. (L.), Piper betle. (L.), Spilanthes acmella. (L.) Murray, and Zingiber zerumbet. (L.) Roscoe ex Sm. and the methanol extract of Boesenbergia rotunda.. Chloroform extract of Alpinia galanga. demonstrated the greatest inhibition zones of 29.1 and 23.7 mm against Staphylococcus aureus. and MRSA, respectively. The MIC values of this extract against Staphylococcus aureus. and MRSA were 128 and 256 µg/ml and the MBC values were 256 and 256 µg/ml, respectively. An active compound, 1′-acetoxy-chavicol acetate, was identified with MIC values against MRSA and Staphylococcus aureus. of 64 and 128 µg/ml, respectively.     

Frequencies of resistance to Melaleuca alternifolia (tea tree) oil and rifampicin in Staphylococcus aureus, Staphylococcus epidermidis and Enterococcus faecalis

This study was conducted to determine the frequencies at which single-step mutants resistant to tea tree oil and rifampicin occurred amongst the Gram-positive organisms Staphylococcus aureus, Staphylococcus epidermidis and Enterococcus faecalis. For tea tree oil, resistance frequencies were very low at <10(-9). Single-step mutants resistant to tea tree oil were undetectable at two times the minimum inhibitory concentration (MIC) for S. aureus RN4220 and derivative mutator strains or at 3 x MIC for the remaining S. aureus strains, including a clinical meticillin-resistant S. aureus isolate. Similarly, no mutants were recovered at 2x MIC for S. epidermidis or at 1x MIC for E. faecalis. Resistance frequencies determined in vitro for rifampicin (8 x MIC) ranged from 10(-7) to 10(-8) for all isolates, with the exception of the S. aureus mutator strains, which had slightly higher frequencies. These data suggest that Gram-positive organisms such as Staphylococcus and Enterococcus spp. have very low frequencies of resistance to tea tree oil.     

Antimicrobial activity of 9-O-acyl- and 9-O-benzoyl-substituted berberrubines

In the course of a structure-activity relationship study on berberrubine derivatives, a series of compounds bearing 9-O-acyl-(4-6) and 9-O-benzoyl- (7) substituents was synthesized with the expectation of increasing the antimicrobial activity. One of the berberrubine derivatives, 9-lauroylberberrubine chloride was the most active against Gram-positive bacteria Enterococcus faecalis, Staphylococcus aureus, Staphylococcus epidermidis, Micrococcus luteus, Bacillus subtilis as well as the Gram-negative bacterium Klebsiella pneumoniae in comparison to berberine, the currently used antibiotic in clinic. This result suggested that the presence of lipophilic substituents of certain structures and sizes might be crucial for the optimal antimicrobial activity.     

Antibacterial activities of piperacillin in several fresh clinical isolates

We investigated activity of piperacillin (PIPC) in comparison with 8 antibacterial reference drugs against several fresh clinical strains isolated from patients with infectious diseases in the respiratory tract and after surgical interventions in 1999. The following results were obtained: 1. PIPC had its MIC90 of 0.12-6 micrograms/ml in Gram-positive bacteria (Methicillin susceptible Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pyogenes, Streptococcus agalactiae, Streptococcus pneumoniae, Enterococcus faecalis) and showed its MIC of 1 microgram/ml or higher in 9 possible PRSP strains out of 38 isolates of S. pneumoniae but there were no possible isolates with evident resistance in other species of bacteria. 2. PIPC showed favorable antibacterial activities as its MIC90 were 2-8 micrograms/ml in Gram-negative bacteria (Escherichia coli, Klebsiella pneumoniae, Serratia marcescens, Citrobacter freundii, Pseudomonas aeruginosa, Moraxella (Branhamella) catarrhalis, Haemophilus influenzae), except for P. mirabilis in which its MIC90 was as high as 64 micrograms/ml. 11 out of 39 isolates of P. mirabilis were resistant to other drugs such as PIPC, ABPC, CTM and CZOP. 3. PIPC had its MIC90 of > 128 micrograms/ml in Bacteroides fragilis. From these results, PIPC was considered highly effective in several infections in view of maintaining its favorable antibacterial activities in several causative bacteria even today when 20 years had passed since its first application to clinical practice.     

Antibacterial and antioxidant activity of methanol extract of Evolvulus nummularius

Objective:

To evaluate the antibacterial and antioxidant activity of methanol extract of Evolvulus nummularius (L) L.

Materials and Methods:

Disc diffusion and broth serial dilution tests were used to determine the antibacterial activity of the methanol extract against two Gram-positive bacterial strains (Bacillus subtilus NCIM 2718, Staphylococcus aureus ATCC 25923) and three Gram-negative bacterial strains (Pseudomonas aeruginosa ATCC 27853, Klebsiella pneumoniae ATCC 70063 and Escherichia coli ATCC 25922). The methanol extract was subjected to preliminary phytochemical analysis. Free radical scavenging activity of the methanol extract at different concentrations was determined with 2, 2-diphenyl-1picrylhydrazyl (DPPH).

Results:

The susceptible organisms to the methanol extract were Escherichia coli (MIC=12.50 mg/ml) and Bacillus subtilus (MIC=3.125 mg/ml) and the most resistant strains were Staphylococcus aureus, Klebsiella pneumoniae and Pseudomonas aeruginosa. The methanol extracts exhibited radical scavenging activity with IC50 of 350 μg/ml.

Conclusion:

The results from the study show that methanol extract of E.nummularius has antibacterial activity. The antioxidant activity may be attributed to the presence of tannins, flavonoids and triterpenoids in the methanol extract. The antibacterial and antioxidant activity exhibited by the methanol extract can be corroborated to the usage of this plant in Indian folk medicine.     

帕尼培南-倍他米隆体外抗菌活性及其对肺部感染病人的疗效观察

目的 :了解帕尼培南 倍他米隆对临床常见致病菌的体外抗菌活性及治疗肺部感染的有效性及安全性。方法 :采用琼脂二倍稀释法测定帕尼培南 倍他米隆对 2 4 7株临床分离菌的MIC ,检测其对部分菌株的最低杀菌浓度 ;2 0例肺部感染病人使用帕尼培南 倍他米隆 5 0 0 /5 0 0mg ,q 12h ,iv ,gtt ,疗程3～ 7d。结果 :帕尼培南 倍他米隆与帕尼培南的体外抗菌活性基本一致 ,MIC50 ≤ 0 .0 0 75mg·L- 1,MIC90 为 0 .0 0 75～ 2mg·L- 1;对流感嗜血杆菌的MIC范围为 <0 .0 0 75～ 0 .12 5mg·L- 1;对阴沟肠杆菌、变形肠杆菌、铜绿假单孢菌的MIC50 和MIC90 分别为 0 .12 5和 0 .5 ,2和 4 ,4和 16mg·L- 1;帕尼培南 倍他米隆对金黄色葡萄球菌、表皮葡萄球菌、铜绿假单孢菌、肺炎克雷伯菌、大肠埃希菌、阴沟肠杆菌、变形肠杆菌及微球菌的最低杀菌浓度分别是其MIC的 1～ 8倍。致病菌阴转率为 77.8% ,治疗有效率为 75 % ,未出现明显不良反应。结论 :帕尼培南 倍他米隆对临床常见致病菌的体外抗菌活性强 ;对肺部感染有较好疗效 ,安全性好     

Antibacterial Effects of the Bark of Terminalia arjuna: Justification of Folklore Beliefs

Antibacterial activity of crude drug from the tree bark of T. arjuna was tested against bacteria using the hole-plate diffusion method with concentrations of 5–25 mg/ml. The effective results of bacterial activity were confirmed by the dilution method (1.25–20 mg/ml) in MIC. The above results were supported by phytochemical analysis. Specific activity against pathogenic bacterium, Bacillus subtilis and Staphyloccus aureus, confirm the traditional usage of bark of T. arjuna.     

血流感染病原菌分布及耐药特性分析

目的了解血流感染主要病原菌的分布特点及对常用抗菌药物的耐药情况,以指导临床合理用药。方法对2006年1月—2011年6月期间本院临床各科室送检的血培养标本采用美国Bactec9120全自动血培养仪进行培养,Vitek-32型仪进行菌种鉴定,纸片扩散法测定菌株对抗菌药物的敏感性,头孢西丁法检测耐甲氧西林葡菌球菌,WHONET5.6软件分析数据。结果共分离出598株病原菌,其中革兰阳性球菌282株,占47.2%;革兰阴性杆菌289株,占48.3%,真菌15株,占2.5%。最常见的感染菌分别为大肠埃希菌、表皮葡萄球菌、肺炎克雷伯菌、金黄色葡萄球菌、铜绿假单胞菌及鲍曼不动杆菌。金黄色葡萄球菌和表皮葡萄球菌中耐甲氧西林葡萄球菌检出率分别为63.9%和87.9%,其对青霉素耐药率均>95.0%,均未发现对万古霉素和替考拉宁耐药株。大肠埃希菌和肺炎克雷伯菌对碳青霉烯类抗生素耐药率最低,对氨苄西林耐药率分别为93.8%和100%。铜绿假单胞菌对亚胺培南耐药率为16.7%,而鲍曼不动杆菌对亚胺培南耐药率高达63.6%,鲍曼不动杆菌对其他抗菌药物的耐药率均>60%。结论本单位血流感染以大肠埃希菌和葡萄球菌为主。表皮葡萄球菌较金黄色葡萄球菌耐药性严重,非发酵菌比肠杆菌科细菌耐药性严重,尤其是鲍曼不动杆菌引起的血流感染无经验抗菌药物可选,必须在药敏试验指导下用药。     

Chloropolysporins A, B and C, novel glycopeptide antibiotics from Faenia interjecta sp. nov. V. Comparative studies of the biological properties

Chloropolysporins A, B and C, as well as derivatives prepared from this group and alpha- and beta-avoparcins by enzymatic and mild acid hydrolysis, were active against Gram-positive bacteria including clinically isolated methicillin-resistant Staphylococci (MIC 0.39-6.25 micrograms/ml) and anaerobic enterobacteria (MIC 0.10-1.56 micrograms/ml). Derhamnosyl and demannosyl derivatives from both groups of antibiotics showed stronger activities than the parent compounds. The MIC and MBC values against Staphylococci were similar and were not effected by the presence of serum. Moreover, chloropolysporin C exhibited very strong synergistic effects with various beta-lactam antibiotics against methicillin-resistant strains of Staphylococcus aureus. Some of these compounds also protected mice from experimental infection with S. aureus. Acute toxicities of chloropolysporin by intravenous administration ranged from 215-290 mg/kg in mice. Chloropolysporin B as well as other glycopeptide antibiotics, showed distinctive growth promoting activity in broiler chickens.