In vitro antimicrobial susceptibility of anaerobic bacteria isolated from caprine footrot

The in vitro antimicrobial susceptibility of Gram-negative anaerobic bacilli commonly isolated from footrot in goats was studied. A total of 97 isolates belonging to the genera Dichelobacter, Fusobacterium, Prevotella, Porphyromonas and Bacteroides, obtained from clinical cases of footrot in south-western Spain between March 2000 and May 2001, were tested against 25 antimicrobial agents comprising beta-lactams, aminoglycosides, macrolides, chloramphenicol, quinolones, lincosamides, sulphonamides and tetracyclines in order to optimise antibiotic treatment of this disease in goats. beta-lactams, tetracyclines and metronidazole displayed the highest in vitro efficacy against the species involved in the pathogenesis of footrot.     

In vitro susceptibility of Staphylococcus aureus strains isolated from cows with subclinical mastitis to different antimicrobial agents

Sensitivity to commercial teat dips (nonoxinol-9 iodine complex and chlorhexidine digluconate) of 56 Staphylococcus (S.) aureus strains isolated from quarter milk samples of various German dairy herds treated with different teat dipping schemes was investigated in this study. The minimum inhibitory concentration was determined using a broth macrodilution method according to the German Veterinary Association guidelines. The main objective of the current study was to induce in vitro resistance induction of S. aureus to chemical disinfectants. Ten different strains were repeatedly passed ten times in growth media with sub-lethal concentrations of disinfectants. Nine strains showed a significant reduction in susceptibility to the nonoxinol-9 iodine complex but only one strain developed resistance to chlorhexidine digluconate. Stability of the acquired resistance was observed in all S. aureus strains adapted to the nonoxinol-9 iodine complex and chlorhexidine digluconate. In contrast, simultaneous resistance to different antibiotics was not observed in any of the ten investigated S. aureus strains. However, the isolates exhibited a high degree of resistance to penicillin G. Based on these results, resistance of S. aureus to chemical disinfectants may be more likely to develop if the chemicals are used at concentrations lower than that required for an optimal biocidal effect.     

大环内酯类抗生素对畜禽病原菌体外抗菌敏感性试验研究

针对兽医临床的细菌耐药现象,为指导临床合理用药,采用微量肉汤稀释法研究了三代大环内酯类抗生素泰乐菌素、替米考星和泰地罗新对兽医临床常见的15种共74株病原菌的体外抑菌效果。结果显示:对于革兰阳性菌,泰乐菌素和替米考星对乳房炎常见的金黄色葡萄球菌、猪链球菌、无乳链球菌、停乳链球菌均有较强的抑菌活性,优于泰地罗新;泰地罗新对肺炎链球菌抑菌效果较强。对于革兰阴性菌,如支气管败血波氏杆菌、溶血性曼氏杆菌、胸膜肺炎放线杆菌、副猪嗜血杆菌等致病菌,替米考星的抑菌效果比泰乐菌素强1～64倍,泰地罗新比替米考星强2～32倍。对引起肠道感染的大肠杆菌,泰地罗新亦表现出很好的抑菌活性,效果优于泰乐菌素和替米考星。本试验为畜禽细菌性疾病的防控以及大环内酯类抗菌药物的合理使用提供了基础数据。     

In vitro antimicrobial susceptibility of Streptococcus suis strains isolated from clinically healthy sows in China

Streptococcus suis is an important pathogen in the swine industry. Because transmission is generally thought to occur between healthy carrier sows and their offspring, it is important to understand which antimicrobial agents are likely to be effective against the strains isolated. This study is the first to report on the antimicrobial susceptibility of S. suis isolated from clinical healthy sows. From 2005 to 2007 a total of 421 S. suis isolates were recovered from sows in China and subjected to antimicrobial susceptibility testing in accordance with the Clinical and Laboratory Standards Institute (CLSI) standards. High-level resistance were found with tetracycline (91.7%) and sulfisoxazole (86.7%), followed by clindamycin (68.4%), erythromycin (67.2%), tilmicosin (66.7%) and trimethoprim/sulfamethoxazole (59.1%). These six antimicrobial agents presented the highest MIC(50) values and the antibiogram (19.2%) most frequently observed. Lower resistance rates among the beta-Lactams support their use as the primary drugs to treat the infection of S. suis. However, appropriate dosing or combination antibiotic therapeutic regimens should be adhered to in view of the resistant and intermediate strains to penicillin (9.5% and 42.3%), ampicillin (4.0% and 29.9%) and ceftiofur (22.1% and 37.3%), respectively.     

豫北地区临床分离鸡大肠杆菌的体外抑菌作用测定

为了有效地治疗鸡大肠杆菌病,采用微量倍比稀释方法测定了17种抗菌药物对临床分离的豫北地区15株鸡大肠杆菌的体外最小抑菌浓度（MIC）,并根据其MIC及MIC范围（MICRange）使用SPSS 13.0中Probit过程计算出17种抗菌药物的MIC50和MIC90。结果表明：多粘菌素B的抑菌作用最强,MIC50、MIC90分别为0.11、0.87μg/mL;加替沙星的抑菌作用次之,MIC50、MIC90分别为2.53、3.88μg/mL,其它3种药物恩诺沙星、左氧氟沙星、环丙沙星的抑菌作用相当,但不及加替沙星,MIC50、MIC90分别为10.11-11.79μg/mL、15.16-21.13μg/mL;多西环素和阿莫西林等12种抗菌药物的抑菌作用较小,MIC50、MIC90分别为18.53-388.50μg/mL和30.59-713.42μg/mL。     

In vitro antimicrobial susceptibility of 183 Pseudomonas aeruginosa strains isolated from dogs to selected antipseudomonal agents

During the years from 1993 to 2000, 183 strains of Pseudomonas aeruginosa were isolated from different pathological specimens originating from dogs. Antimicrobial susceptibility patterns against 10 antipseudomonal agents were obtained on 183 P. aeruginosa strains. In vitro antimicrobial susceptibility testing was performed using the disk diffusion method (Kirby-Bauer). Antimicrobial susceptibility profiles showed that among beta-lactam antibiotics, imipenem was the most active compound. Out of the 183 strains tested, 96.7% were sensitive to imipenem. Cefoperazone showed good in vitro activity against 86.9% of the tested strains. Against ceftazidime, 77.0% of strains showed sensitivity. An old penicillin, carbenicillin, gave only 71.6% sensitive strains. Sensitivity to amikacin was 87.4% and it was 83.1% to gentamicin. Pipimedic acid, a first-generation quinolone, was the least active compound of all those tested, 47.0% were resistant. The in vitro sensitivity against enrofloxacin showed that 71.0% strains were sensitive and 26.2% showed resistance. Almost all strains tested, 93.4%, were susceptible to ciprofloxacin and marbofloxacin. Besides imipenem, the quinolone antibiotics, marbofloxacin and ciprofloxacin were the most effective against P. aeruginosa strains isolated from dogs.     

In vitro susceptibility of Escherichia coli strains isolated from diarrhoeic dairy calves to 15 antimicrobial agents

The in vitro activities of 15 antimicrobial agents against 195 strains of Escherichia coli isolated from dairy calves affected by neonatal diarrhoea were determined. Of these strains 137 produced one or more potential virulence factors (F5, F41, F17, cytotoxic necrotizing factor, verotoxin and the eae gene), but the remaining 58 strains did not produce any of these factors. The overall percentage of resistant strains to streptomycin, tylosin and tetracycline was very high (above 65%). A high level of resistance (from 23 to 50%) to ampicillin, neomycin, kanamycin, spectinomycin, chloramphenicol, sulphadimethoxine and trimethoprim was also detected. The E. coli strains were very susceptible (89-95%) to apramycin and gentamicin and highly susceptible (99-100%) to polymyxin B, florfenicol and nitrofurazone. Some significant differences (P < 0.05) in the frequencies of resistance to some of the antimicrobials tested and in the rates of multi-drug resistance among the strains producing potential virulence factors and non-fimbriated, non-toxigenic, eae-negative strains were found. Most of the strains showed multi-resistance: 76.9% of the isolates were resistant to at least two antibiotics, 67.7% were resistant to at least four antibiotics and 50.3% were resistant to at least six antibiotics.     

体外模拟消化研究不同来源木聚糖酶对麸皮降解的影响

小麦是我国主要的粮食作物之一,作为小麦加工的主要副产品,麦麸比例占加工总量的20%。以2009年我国小麦总产量1.46亿t计,麦麸产量可达2120万t。尽管麦麸的降解效率较低,但传统的利用途径依然以饲料资源为主。小麦麸皮所含的抗营养成分可降低饲料消化利用率,引起畜禽生产性能、胴体质量下降;     

In vitro drug susceptibility pattern of Mycoplasma alligatoris isolated from symptomatic American alligators (Alligator mississippiensis).

A recently described mycoplasma, Mycoplasma alligatoris, was isolated from dead American alligators (Alligator mississippiensis) that had demonstrated clinical signs of lethargy, anorexia, bilateral ocular discharge, edema. paraparesis, and polyarthritis. The in vitro minimum inhibitory concentration for nine antibacterial agents was determined through serial dilution in broth and plate culture for M. alligatoris isolates. The inhibitory concentration obtained for doxycycline, enrofloxacin, sarafloxacin, oxytetracycline, tilmicosin, and tylosin (< 1 microg/ml) was lower than that of clindamycin (1-8 microg/ml), chloramphenicol (8-16 microg/ml), and erythromycin (32-138 microg/ml).     

体外模拟消化研究不同来源木聚糖酶对能量饲料原料降解的影响

考察不同来源木聚糖酶对饲料原料的降解效果。通过将不同来源的木聚糖酶同时配制成复合酶作用于不同原料小麦、DDGS和美国玉米,进行体外消化模拟试验,发现消化率较单一木聚糖酶配制的复合酶分别提高36.5%、37.8%和66.9%,粗蛋白质消化率分别提高1.48%、9.19%和9.31%,粗纤维消化率分别提高1.38%、9.6%和7.12%。说明多种来源木聚糖酶对日粮的消化效果要优于单一木聚糖酶。     

In vitro susceptibility of Escherichia coli strains isolated from diarrhoeic lambs and goat kids to 14 antimicrobial agents

The in vitro activities of 14 anti-microbial agents were determined against 92 strains of E. coli isolated from lambs (60 strains) and kids (32 strains) affected by neonatal diarrhoea. The overall percentage of resistant strains to streptomycin, sulphadimethoxine and tetracycline was very high (above 70%). A high level of resistance (from 30% to 50%) to ampicillin, kanamycin, neomycin and chloramphenicol was also detected. The E. coli strains were highly susceptible to cephalosporins, polymyxin and quinolones. Most of the strains showed multiresistance: 77.2% of isolates were resistant to at least two antibiotics, 55.4% were resistant to at least four antibiotics and 33.7% were resistant to at least six antibiotics. A total of 34 antibiotypes could be distinguished.     

In vitro susceptibility of 21 antimicrobial agents to 37 isolates of Brachyspira hyodysenteriae isolated from pigs in Okinawa Prefecture

The in vitro susceptibilities to 21 antimicrobial agents, of 37 isolates of Brachyspira (B.) hyodysenteriae isolated from pigs in Okinawa meat center and a pig farm in Okinawa Prefecture, Japan, were determined by the agar dilution method. Carbadox was the most active of all the agents tested against the isolates (MIC: <0.003 to 0.05). All the isolates were highly susceptible to olaquindox, tiamulin, dimetridazole, efrotomycin and valnemulin with MICs ranging from 相似文献   

盐酸沙拉沙星的体外抗菌作用

盐酸沙拉沙星具有抗菌谱广、杀菌力强的特点。试验用盐酸沙拉沙星对 4种细菌的体外抗菌活性进行了研究。结果显示 :该药对大肠杆菌O78、金黄色葡萄球菌、鸡沙门氏菌、大肠杆菌O2 均很敏感。其最小抑菌浓度 (MIC)分别为 0 0 62 5 ,0 5 ,0 1 2 5 ,0 1 2 5 μg/mL ,最低杀菌浓度(MBC)分别为 0 0 62 5 ,0 5 ,0 1 2 5 ,0 1 2 5 μg/mL。较同类药物盐酸恩诺沙星、甲磺酸培氟沙星的抗菌作用强。结果同时显示 ,该药抗菌活性不受或少受细菌接种量及加入不同小牛血清量的影响。     

马波沙星对猪临床分离病原菌的体外抑菌活性研究

考察马波沙星对猪临床分离病原菌的体外抑菌活性,以期为临床应用提供依据。采用琼脂二倍稀释法测定马波沙星对猪临床分离大肠杆菌、金黄色葡萄球菌和链球菌的最小抑菌浓度(MIC),并以土霉素、恩诺沙星、诺氟沙星、环丙沙星、庆大霉素和多西环素作为对照药物。结果表明:马波沙星对猪临床分离病原菌大肠杆菌、金黄色葡萄球菌和链球菌均有较低的最小抑菌浓度,对临床分离大肠杆菌、金黄色葡萄球菌和链球菌的抑菌活性明显高于诺氟沙星、环丙沙星、庆大霉素和强力霉素,对临床分离大肠杆菌的抑菌活性高于恩诺沙星。马波沙星对引起猪乳房炎-子宫炎-无乳综合征(MMA)的主要病原菌的抑菌活性优于常用抗菌药。     

In vitro susceptibility to antimycotics of Microsporum canis isolates from cats.

One hundred thirty-four isolates of Microsporum canis, obtained from cats, were tested for in vitro susceptibility to various antifungal agents. The fungi were classified as susceptible, resistant, and intermediate by measuring the size of the zone of inhibited growth on yeast nitrogen base agar medium. Clotrimazole had the highest activity (99.2%), followed by tioconazole (89.6%), griseofulvin (88.8%), econazole (73.1%), ketoconazole (50.7%), miconazole (15.7%), and isoconazole (12.7%). We found 14.9% of the isolates to be susceptible to all the assayed drugs, whereas the highest resistance frequency (41.8%) was against 2 antimycotics. A simultaneous resistance to all the tested antimycotics was not found. The differences among the antifungal drugs activity were examined, and administration of drugs for which a simultaneous resistance was minimal is suggested.     

Identification of putative adhesin genes in shigatoxigenic Escherichia coli isolated from different sources

Shiga toxin-producing Escherichia coli (STEC) is an important pathogen responsible for severe human intestinal and systemic infections. The bacterial factors required for colonization of the hosts are still not well defined. In this study, the prevalence of seven putative adhesive genes that are not encoded in the locus of enterocyte effacement (LEE) in 74 STEC strains isolated from humans (n=39), food (n=6), cattle (n=11), and pigs (n=18) was investigated by PCR. In addition, Shiga toxin (stx) and intimin (eaeA including alpha, beta, gamma, delta, epsilon, zeta variants) genes were tested. The most prevalent adhesin was that encoded by toxB gene (52 of 74 isolates; 70.3%). This marker was found in all 12 strains of O157:H7 serotype and in 23 of 32 (71.9%) isolates of the O157:NM serogroup. Moreover, this gene was also present in other 17 STEC of the non-O157 serogroup. The second most prevalent adhesin was that encoded by the lpfAO157/OI-154 gene (43 isolates; 58.1%). This marker was detected in LEE-positive strains of the O157 serogroup but also in 9 LEE-negative isolates of porcine origin. Several STEC isolates tested (42 strains; 56.7%) had the efa1 gene of the Efa1 putative adhesive marker. This adhesin was almost exclusively found among eaeA-positive strains recovered from humans, food and cattle. On the other hand, iha marker was detected either in LEE-positive (29 isolates) or LEE-negative (12 strains) STEC. Only two eaeA-negative strains had the saa putative adhesive gene. These results show that STEC strains may be able to express several putative adhesins. However, further studies are needed to evaluate the role of the genes identified in the present study in the pathogenesis of human infections.