In vitro activity of AT-4140 against clinical bacterial isolates.

The activity of AT-4140, a new fluoroquinolone, was evaluated against a wide range of clinical bacterial isolates and compared with those of existing analogs. AT-4140 had a broad spectrum and a potent activity against gram-positive and -negative bacteria, including Legionella spp. and Bacteroides fragilis. The activity of AT-4140 against gram-positive and -negative cocci, including Acinetobacter calcoaceticus, was higher than those of ciprofloxacin, ofloxacin, and norfloxacin. Its activity against gram-negative rods was generally comparable to that of ciprofloxacin. Some isolates of methicillin-resistant Staphylococcus aureus (MIC of methicillin, greater than or equal to 12.5 micrograms/ml) were resistant to existing quinolones, but many of them were still susceptible to AT-4140 at concentrations below 0.39 micrograms/ml. The MICs of AT-4140, ciprofloxacin, ofloxacin, and norfloxacin for 90% of clinical isolates of methicillin-resistant S. aureus were 0.2, 12.5, 6.25, and 100 micrograms/ml, respectively. AT-4140 was bactericidal for each of 20 clinical isolates of Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, Serratia marcescens, and Pseudomonas aeruginosa at concentrations near the MICs. AT-4140 inhibited the supercoiling activity of DNA gyrase from E. coli.     

In vitro activity of SCH 27899 (Ziracin) against Legionella species

The activities of Sch 27899 (Ziracin), erythromycin, and ofloxacin against 102 Legionella spp. isolates were measured by a microbroth dilution method. The MICs that inhibited 90% of strains tested were 0.25, 0.5, and 0.06 μg/mL for Sch 27899, erythromycin, and ofloxacin, respectively. The activity of Sch 27899 against intracellular Legionella pneumophila could not be determined because of complete inactivation of the drug by tissue culture medium components.     

In vitro antimicrobial activity of aztreonam alone and in combination against bacterial isolates from pediatric patients

We examined 134 pediatric clinical isolates of Enterobacteriaceae, Pseudomonas aeruginosa, and gram-positive cocci for susceptibility to aztreonam alone and in combination with seven other antibiotics. All 98 gram-negative isolates were susceptible to aztreonam with similar inhibitory and bactericidal activity. Combinations of aztreonam with cefoxitin, ampicillin, or clindamycin were generally indifferent or additive. Synergism was occasionally seen against enteric organisms with aztreonam plus cefoxitin or clindamycin. Combinations of tobramycin and aztreonam were synergistic (62%) against P. aeruginosa; aztreonam plus piperacillin or ticarcillin was additive. Aztreonam did not affect the activity of nafcillin against Staphylococcus aureus, or of ampicillin against species of Streptococcus group B or D. Antagonism was seen only with aztreonam plus cefoxitin against Enterobacter species, but not at clinically significant concentrations. Several combinations of antibiotics with aztreonam should be appropriate for initial therapy of infections in children without major risks of antibacterial antagonism.     

In vitro activity of PD127,391, a new quinolone against bacterial isolates from cancer patients

The in vitro activity of PD127,391, a new 4-quinolone, was compared to that of ciprofloxacin against common clinical bacterial isolates from patients with cancer. PD127,391 was found to have a broad antimicrobial spectrum with excellent activity against gram-positive isolates (including multidrug-resistant organism such as Corynebacterium jeikeium, Enterococcus faecalis, Enterococcus faecium, methicillin-resistant Staphylococcus aureus and coagulase-negative Staphylococcus spp.). It was also extremely active against gram-negative bacilli including Pseudomonas aeruginosa. Against organisms such as Achromobacter xylosoxidans, Acinetobacter spp. and Xanthomonas maltophilia, which are frequently resistant to a variety of antimicrobial agents, PD127,391 exhibited good activity, inhibiting all such isolates at a concentration of 0.5 micrograms/ml. Overall, PD127,391 was far more potent than ciprofloxacin against gram-positive isolates and slightly more active against gram-negative isolates. No bacterium that we examined needed more than 2 micrograms/ml of PD127,391 for inhibition.     

In vitro studies of the synergism of piperacillin and netilmicin against blood culture isolates

The purpose of this study was to evaluate the in vitro synergism between piperacillin and netilmicin against microorganisms isolated from Danish patients with septicemia and to examine the influence of inactivation of piperacillin among these bacteria on the synergy results. A total of 132 stains was examined: Escherichia coli 20, indole-positive Proteus 17, Klebsiella pneumoniae 18, Enterobacter cloacae 20, Pseudomonas aeruginosa 20, Staphylococcus aureus 20, and coagulase-negative staphylococci 17. Synergy testing was performed by checkerboard titration in microtiter trays. The ability of the strains to inactivate piperacillin was examined by the clover-leaf test. Synergism was found for 52% of the strains and partial synergism for 32%. Antagonism was not found. Of the piperacillin-resistant strains synergism could be demonstrated in 80% compared with 33% of the piperacillin-susceptible strains (p less than 0.001). No significant correlation was seen between the results of the synergy test and the results of the susceptibility test to netilmicin. The frequency of piperacillin inactivation according to the clover-leaf test was significantly higher among the strains with synergism than among all the others (p less than 0.02). The combination of piperacillin and netilmicin gave good results concerning the in vitro synergism. This synergism was probably sometimes caused by netilmicin disturbing the bacterial production of piperacillin-inactivating proteins.     

In vitro activity of BMY-28100 against common isolates from pediatric infections.

The antibacterial activity of BMY-28100, a new oral cephalosporin, was measured against 300 bacterial isolates from pediatric infections by standard agar dilution methodology. The effect of inoculum size on activity was also assessed. BMY-28100 was more active than cephalexin or cefaclor against all bacterial species tested.     

磷霉素氨丁三醇对尿标本中肠杆菌科细菌体外抗菌活性研究

目的了解磷霉素氨丁三醇对尿标本中肠杆菌科细菌的体外抗菌活性,指导临床合理用药。方法采用ATB系统对中段尿标本分离的1185株肠杆菌科细菌进行鉴定,纸片扩散法进行药敏试验和ESBI．S的检测,结果按CLSI2012年版标准判断;应用WHONET5．6软件分析病原菌的分布及耐药情况。结果1185株肠杆菌科细菌对磷霉素氨丁三醇的敏感率为90．8％,其中大肠埃希菌929株（78．4％）、肺炎克雷伯菌124株（10．5％）和奇异变形杆菌69株（5．8％）对磷霉素氨丁三醇的敏感率分别为93．1％、88．7％和79．7％。住院患者尿标本分离的肠杆菌科细菌对磷霉素氨丁三醇的敏感率低于门诊患者（87．0％对92．7％）。大肠埃希菌、肺炎克雷伯菌和奇异变形杆菌ESBLs的检出率分别为54．4％、38．7％和23．2％。产ESBLs的大肠埃希菌和肺炎克雷伯菌对磷霉素氨丁三醇的敏感率分别为89．5％和87．5％。结论尿标本培养获得的肠杆菌科细菌以大肠埃希菌为主,磷霉素氨丁三醇对尿标本分离的产ESBLs的大肠埃希菌和肺炎克雷伯菌的肠杆细菌科细菌具有良好的体外抗菌活性,可作为临床经验用药之一。     

In vitro activity of sparfloxacin (CI-978; AT-4140) against clinical isolates from cancer patients.

The in vitro activity of sparfloxacin, a new quinolone, was compared with those of ciprofloxacin and fleroxacin against gram-positive and gram-negative bacteria, greater than 90% of which were isolated from blood culture specimens of cancer patients. Sparfloxacin was extremely active against Acinetobacter species, Aeromonas hydrophila, Citrobacter diversus, Enterobacter species, Escherichia coli, Klebsiella species, Proteus vulgaris, and Serratia marcescens (inhibiting greater than 90% of these isolates at a concentration of 0.5 microgram/ml) and moderately active against Pseudomonas species, other Proteus species, and Citrobacter freundii. Sparfloxacin inhibited greater than 90% of staphylococci (including methicillin-resistant and coagulase-negative strains) at a concentration of 0.12 microgram/ml and greater than 90% of streptococci (including Streptococcus pneumoniae) at a concentration of 1.0 microgram/ml. It was also active against Bacillus cereus, Enterococcus species, and Corynebacterium jeikeium, organisms that have become fairly common in cancer patients.     

In vitro activity of azithromycin against bacterial enteric pathogens.

The in vitro activity of azithromycin against enteric bacterial pathogens was determined by agar dilution. Azithromycin was highly active against Campylobacter spp. (MIC for 90% of strains tested [MIC90] = 0.125 micrograms/ml) and against enterotoxigenic, enterohemorrhagic, enteroinvasive, and enteropathogenic Escherichia coli (MIC90 = 2 micrograms/ml), Shigella spp. (MIC90 = 1 micrograms/ml), and Salmonella spp. (MIC90 = 4 micrograms/ml), including Salmonella typhi (MIC90 = 1 microgram/ml). On the basis of the in vitro activity of the drug against these organisms, clinical studies of azithromycin in enteric diseases should be considered; the high intracellular concentrations achieved by azithromycin may be particularly relevant for organisms like S. typhi, Campylobacter spp., and Shigella spp. which typically invade cells as part of their infectious process.     

In vitro activities of ertapenem (MK-0826) against clinical bacterial isolates from 11 North American medical centers

This study compared the in vitro activities of the new long-half-life carbapenem ertapenem (also known as MK-0826 and L-749,345) with those of imipenem, amoxicillin-clavulanate, and ciprofloxacin against 5,558 recent clinical isolates from 11 North American medical centers. We confirmed the greater activity of ertapenem than of imipenem against the Enterobacteriaceae and the greater activity of imipenem against pseudomonads and gram-positive bacteria.     

In vitro activity and mode of action of diastereomeric antimicrobial peptides against bacterial clinical isolates

OBJECTIVES: Increasing resistance of pathogenic bacteria to antibiotics is a severe problem in health care and has intensified the search for novel drugs. Cationic antibacterial peptides are the most abundant antibiotics in nature and have been frequently proposed as new anti-infective agents. Here, a group of diastereomeric (containing d- and l-amino acids) peptides is studied regarding their potency against multiply resistant clinical isolates and their modes of action against Gram-positive cocci. METHODS: MIC determinations and chequerboard titrations followed established procedures. Mode of action studies included killing kinetics and a series of experiments designed to characterize the impact of the diastereomeric peptides on bacterial membranes. RESULTS: The tested diastereomers displayed high antimicrobial and broad spectrum activity with amphipathic-2D being the most active peptide. Synergic activities were observed with individual strains. Mode of action studies clearly demonstrated that the cytoplasmic membrane is a primary target for the peptides and that membrane disruption constitutes a significant bactericidal activity for the major fraction of a bacterial population. However, depending on the indicator strain, the results also suggest that additional molecular events contribute to the overall activity.     

In vitro activity of daptomycin against 297 staphylococcal isolates

The in vitro activity of daptomycin against 297 clinical isolates of Staphylococcus aureus and S. epidermidis sensu strictu was compared with the activities of cephalothin, dicloxacillin, tobramycin, and vancomycin. Minimal inhibitory concentrations (MICs) were determined by an agar dilution method. Cephalothin and dicloxacillin showed the highest activity against S. aureus on a weight-for-weight basis, all isolates being inhibited by 0.5 mg/l or less of either agent. Cephalothin was somewhat more active against S. epidermidis than was dicloxacillin. Daptomycin and vancomycin exhibited high and similar activity against both S. aureus and S. epidermidis (MIC90% = 1 and 2 mg/l, respectively). Tobramycin was highly active against S. aureus, but the activity against S. epidermidis was greatly variable (MIC range less than or equal to 0.03 - greater than or equal to 16 mg/l). The activity of daptomycin was markedly influenced by the test medium; the MICs were generally 32 times higher when the isolates were tested on Iso-Sensitest agar than on Mueller-Hinton agar. Supplementation of Iso-Sensitest agar with increasing concentrations of calcium potentiated the activity of daptomycin substantially, the results obtained on Iso-Sensitest agar supplemented with 20 mg Ca2+/l being similar to those obtained on Mueller-Hinton agar.     

In vitro activity of Citrus bergamia (bergamot) oil against clinical isolates of dermatophytes

OBJECTIVES: Recently, bergamot oil was shown to be a potent antifungal agent in vitro against clinically important Candida species. In this study, the activities of bergamot natural essence and its furocoumarin-free and distilled extracts on dermatophytes such as Trichophyton, Microsporum and Epidermophyton species were investigated. METHODS: In vitro susceptibility testing assays on 92 clinical isolates of dermatophytes (Trichophyton mentagrophytes n = 20, Trichophyton rubrum n = 18, Trichophyton interdigitale n = 15, Trichophyton tonsurans n = 2, Microsporum canis n = 24, Microsporum gypseum n = 1 and Epidermophyton floccosum n = 12) were performed using the CLSI M38-A broth microdilution method, except for employing an inoculum of 1-3 x 10(3) cfu/mL. MICs were determined at a visual endpoint reading of 80% inhibition compared with the growth control. RESULTS: MICs (v/v) of all fungi ranged from 0.156% to 2.5% for the natural essence, from 0.02% to 2.5% for the distilled extract, and from 0.08% to 1.25% for the furocoumarin-free extract. The three isolates of T. tonsurans and M. gypseum exhibited the highest MIC values. CONCLUSIONS: Data from this study indicate that bergamot oil is active in vitro against several common species of dermatophytes, suggesting its potential use for topical treatment of dermatophytoses.     

阿莫西林-双氯西林的体外抗菌作用研究

目的评价阿莫西林-双氯西林对常见感染临床分离菌的体外抗菌作用.方法收集临床分离菌按CLSI/NCCLS推荐的琼脂对倍稀释法测定阿莫西林-双氯西林的最低抑菌浓度（MIC）,并与相关抗菌药物进行比较.结果收集临床分离菌共513株,其中需氧革兰阳性菌248株,需氧革兰阴性菌265株.阿莫西林-双氯西林对受试的需氧革兰阳性球菌,包括肺炎链球菌、化脓性链球菌等链球菌属、甲氧西林敏感葡萄球菌、粪肠球菌具有高度抗菌活性,大多与阿莫西林-克拉维酸相仿,亦优于其他受试药,该药对卡他莫拉菌、流感嗜血杆菌抗菌作用强,其中对流感嗜血杆菌的产酶株作用略差;对伤寒沙门菌具有良好抗菌作用,对大肠埃希菌、肺炎克雷伯菌、奇异变形杆菌和志贺菌的抗菌作用较差.结论阿莫西林-双氯西林对社区获得的上、下呼吸道感染和单纯性皮肤软组织感染的常见病原菌具有良好抗菌作用,对伤寒沙门菌作用亦强,提示该药为治疗上述感染的适宜选用药物之一.     

头孢地尼对临床分离菌的体外抗菌活性

目的:测定头孢地尼体外抗菌活性并与其他抗菌药比较。方法:采用琼脂稀释法测定抗生素最低抑菌浓度(MIC)。结果:651株细菌测定结果表明,头孢地尼对甲氧西林敏感金黄色葡萄球菌、表皮葡萄球菌(MSSA、MSSE)抗菌作用与头孢唑林、头孢呋辛相似,较头孢他啶强;对 MSSA、MSSE的 MIC90分别为 1、0.5 mg/L,细菌敏感率分别为 97%、100%。耐甲氧西林金黄色葡萄球菌、表皮葡萄球菌(MRSA、MRSE)、肠球菌对本药耐药,MIC90分别为＞128mg/L、8mg/L、＞128mg/L。头孢地尼对革兰阴性菌抗菌活性与头孢他啶相似,对大肠埃希菌、肺炎克雷伯菌、伤寒杆菌、痢疾杆菌、奇异变形杆菌MIC90分别为 2、4、1、0.25与 2 mg/L,敏感率分别为 85%、88%、100%、100%、88%,对部分细菌抗菌活性较阿米卡星、左氧氟沙星、司帕沙星强。聚团肠杆菌、阴沟肠杆菌、粘质沙雷菌、醋酸钙不动杆菌、铜绿假单胞菌对本药耐药,MIC90均＞128 mg/L。结论:头孢地尼对甲氧西林敏感葡萄球菌属、常见肠杆菌科细菌具强大的抗菌作用。     

In vitro activity of azithromycin against clinical isolates of Legionella species.

The activities of azithromycin, erythromycin, and ciprofloxacin against 21 Legionella isolates were measured by an agar dilution method and in macrophages. The MICs for 90% of strains tested were 2.0, 1.0, and 0.5 micrograms/ml for azithromycin, erythromycin, and ciprofloxacin, respectively. Azithromycin and ciprofloxacin were both bactericidal in the macrophage system, but erythromycin was bacteriostatic.