The efficacy of sulbactam-ampicillin in the therapy of respiratory disease associated with ampicillin resistant Pasteurella species in housed calves

Sulbactam-ampicillin is a combination of sulbactam, a beta-lactamase inhibitor, and ampicillin, a broad spectrum beta-lactam antibiotic. The efficacy of sulbactam-ampicillin was evaluated in the treatment of calf respiratory disease associated with ampicillin-sensitive and ampicillin-resistant strains of Pasteurella haemolytica and Pasteurella multocida. Treatment with sulbactam-ampicillin was compared with treatment with ampicillin alone in 123 Friesian calves, between three and five weeks old, exhibiting clinical signs of respiratory disease. Seven of the 59 calves treated with ampicillin died whereas only one death occurred in the 64 calves treated with sulbactam-ampicillin. In the calves which survived, treatment with sulbactam-ampicillin resulted in a significantly better clinical response, as measured by the reduction in severity of clinical signs. The results of bacteriological examinations indicated that there was a marked increase in the proportion of ampicillin-resistant isolates of P haemolytica subsequent to treatment with ampicillin, whereas the proportion of ampicillin-resistant isolates of P. haemolytica recovered from calves treated with sulbactam-ampicillin had declined. The superior efficacy of sulbactam-ampicillin observed in this study is explained by the inhibitory effect of sulbactam on beta-lactamases produced by resistant bacteria, thus rendering them susceptible to the ampicillin.     

Efficacy of sulbactam-ampicillin in an induced Pasteurella haemolytica pneumonia model in calves

Therapeutic efficacy of sulbactam, a beta-lactamase inhibitor, in combination with ampicillin was evaluated in an ampicillin-resistant Pasteurella haemolytica pneumonia model in cattle, using an IV agar emboli method of infection. Groups of cattle given vehicle (group 1, n = 19) or ampicillin (group 2, n = 8) had 74% and 50% mortality, respectively, whereas group 3 (n = 11) given sulbactam-ampicillin had no mortality. Morbidities were 100% in groups 1 and 2 and 27% in group 3. Retrospectively, mortalities and morbidities were significantly (P less than 0.001) lower for group 3 given sulbactam-ampicillin when compared with those in groups 1 and 2 given vehicle or ampicillin, respectively. Evidence of embolic pneumonic pasteurellosis was observed histologically.     

Efficacy of Sulbactam, a B-lactamase Inhibitor, Combined with Ampicillin in the Therapy of Ampicillin-resistant Pneumonic Pasteurellosis in Veal Calves

Two field efficacy studies, involving a total of 92 naturally infected, pneumonic veal calves, were conducted to compare the efficacy of the β-lactamase inhibitor sulbactam plus ampicillin to ampicillin alone in the treatment of bacterial pneumonia. Cultures from nasal swabs and lung tissue during the 10 or 11 day studies were predominantly ampicillin-resistant Pasteurella multocida. Ampicillin (6.6 mg/kg) or sulbactam-ampicillin (3.3 mg/kg sulbactam + 6.6 mg/kg ampicillin) was injected intramuscularly once daily for either three days or six days. Sulbactam-ampicillin administered once daily for three or six days resulted in lower (P≤0.05) average body temperature with a concomitant clinical improvement (P≤0.05), and produced numerical advantages and/or statistical improvements over ampicillin in mortality, weight gain, and overall response of calves to treatment. The combined mortality for the two studies in the ampicillin and sulbactam-ampicillin treated groups was 43% and 14%, respectively. We concluded that sulbactam-ampicillin was superior to ampicillin in the treatment of ampicillin-resistant bacterial pneumonia in veal calves.     

The plasma kinetics of sulbactam-ampicillin administered to calves by the intramuscular and subcutaneous routes

Sulbactam-ampicillin combines ampicillin, a broad spectrum beta-lactam antibiotic, with sulbactam, an irreversible beta-lactamase inhibitor. The sulbactam component prevents the degradation of ampicillin by several major classes of bacterial beta-lactamases and restores the activity of ampicillin against most strains of bacteria in which resistance is mediated by beta-lactamase production.A crossover study was conducted in Friesian calves of 98–119 kg bodyweight in which the plasma kinetics of sulbactam-ampicillin adminstered by the intramuscular and subcutaneous routes were defined, and the plasma kinetics of ampicillin derived from sulbactam-ampicillin and a commercially available formulation of ampicillin trihydrate were compared. Subsequent to both intramuscular and subcutaneous administration of sulbactam-ampicillin, peak plasma concentrations of sulbactam and ampicillin were recorded two hours post-injection. Higher peak plasma concentrations of both sulbactam and ampicillin were achieved by the subcutaneous route of administration and, for ampicillin, the difference between the two routes was statistically significant (p < 0·01). However, there was no significant difference in bioavailability (as measured by area under the curve) between the two routes of administration for either component. In addition, there were no significant differences between the peak plasma concentrations or areas under the curves for ampicillin derived from intramuscular administration of sulbactam-ampicillin, and ampicillin alone, indicating that combination with sulbactam does not alter the plasma kinetics of ampicillin.     

Efficacy of sulbactam-ampicillin in the treatment of neonatal calf diarrhoea

Sulbactam-ampicillin is a combination of sulbactam, a beta-lactamase inhibitor, and ampicillin, a broad spectrum beta-lactam antibiotic. The efficacy of sulbactam-ampicillin was evaluated in the treatment of neonatal calf diarrhoea under conditions where a major proportion of the calves were excreting enterobacteria which were resistant to beta-lactam antibiotics. In a series of six studies with a common experimental design, three treatments (sulbactam-ampicillin, ampicillin alone and untreated control) were compared in over 300 Friesian and Ayrshire calves aged between three and 10 days and of known immunological status as determined by their zinc sulphate turbidity values. A mortality rate of 26.4 per cent in the negative control calves was reduced to 14.0 per cent with ampicillin alone and 9.5 per cent with sulbactam-ampicillin. The probability of diarrhoea subsequent to initiation of treatment was reduced from 0.50 in the negative control calves to 0.44 with ampicillin alone and 0.35 with sulbactam-ampicillin. The differences in mortality and diarrhoea observed between the calves treated with sulbactam-ampicillin and the calves in each of the other treatment groups were statistically significant. The superior efficacy of sulbactam-ampicillin is explained by the inhibitory effect of sulbactam on the beta-lactamases produced by resistant bacteria, thus rendering them susceptible to the ampicillin in the combination.     

Efficacy of Sulbactam, a B-lactamase Inhibitor, Combined with Ampicillin in the Therapy of Ampicillin-resistant Pneumonic Pasteurellosis in Feedlot Calves

Two field efficacy studies, involving a total of 80 naturally infected feedlot calves, were conducted to compare the efficacy of sulbactam-ampicillin with that of penicillin-dihydrostreptomycin in the treatment of pneumonic pasteurellosis. Cultures from pretreatment nasal swabs were predominantly ampicillin/ penicillin resistant Pasteurella haemolytica. Clinical observations revealed that cattle treated with penicillin-dihydrostreptomycin responded poorly, whereas those treated with sulbactam-ampicillin responded promptly. Twenty-four hours after initiation of treatment, mean body temperatures of the calves in the sulbactam-ampicillin groups had decreased by 2.1°C, whereas, in the penicillin-dihydrostreptomycin calves there was little change. The difference between the two treatments was statistically significant (P≤0.01). The combined mortality for the two studies in the penicillin-dihydrostreptomycin treated groups was 18%. No mortality occurred in the sulbactam-ampicillin treated groups. Our data show that sulbactam-ampicillin was more effective than penicillin-dihydrostreptomycin in the treatment of pneumonia caused by ampicillin/penicillin resistant strains of Pasteurella in feedlot calves.     

In vitro susceptibility of selected veterinary bacterial pathogens to ciprofloxacin, enrofloxacin and norfloxacin.

The minimum inhibitory concentrations (MIC) of ciprofloxacin, enrofloxacin, and norfloxacin were tested for approximately ten clinical isolates of each of Actinobacillus pleuropneumoniae, Actinobacillus suis, Actinomyces pyogenes, Corynebacterium pseudotuberculosis, Erysipelothrix rhusiopathiae, Haemophilus parasuis, Haemophilus somnus, Pasteurella haemolytica, Pasteurella multocida, Rhodococcus equi, Streptococcus equi, Streptococcus suis and Streptococcus zooepidemicus. Ciprofloxacin and enrofloxacin had similar activity and were more active than norfloxacin. All isolates had an MIC of 1.0 microgram/mL or less for ciprofloxacin and enrofloxacin, and these drugs had particularly marked activity against the gram-negative bacteria tested.     

Clinical and pathological evaluation of sulbactam/ampicillin for treatment of experimental bovine pneumonic pasteurellosis

An experiment was conducted to evaluate the efficacy of sulbactam/ampicillin for treatment of bovine pneumonic pasteurellosis. Twenty-one Hereford calves were experimentally infected with bovine herpesvirus-1 and an ampicillin-resistant strain of Pasteurella haemolytica, then treated for three days with either sulbactam/ampicillin, chloramphenicol, or a placebo. The treatments were evaluated by comparing clinical illness scores, total sick days, weight changes, mortality rates, and postmortem lung scores between treatment groups. Both antibiotics were highly effective in reducing respiratory disease in the experimentally infected calves. The clinical response to sulbactam/ampicillin treatment was comparable with that of chloramphenicol and was significantly improved compared with the response to the placebo treatment. These findings suggest that the efficacy of sulbactam/ampicillin may be comparable to that of chloramphenicol for treatment of pneumonic pasteurellosis involving ampicillin-resistant strains of P. haemolytica.     

Minimum inhibitory concentrations of tulathromycin against respiratory bacterial pathogens isolated from clinical cases in European cattle and swine and variability arising from changes in in vitro methodology

The in vitro activity of tulathromycin was evaluated against common bovine and porcine respiratory pathogens collected from outbreaks of clinical disease across eight European countries from 1998 to 2001. Minimum inhibitory concentrations (MICs) for one isolate of each bacterial species from each outbreak were determined using a broth microdilution technique. The lowest concentrations inhibiting the growth of 90% of isolates (MIC90) for tulathromycin were 2 microg/ml for Mannheimia (Pasteurella) haemolytica, 1 microg/ml for Pasteurella multocida (bovine), and 2 microg/ml for Pasteurella multocida (porcine) and ranged from 0.5 to 4 microg/ml for Histophilus somni (Haemophilus somnus) and from 4 to 16 microg/ml for Actinobacillus pleuropneumoniae. Isolates were retested in the presence of serum. The activity of tulathromycin against fastidious organisms was affected by culture conditions, and MICs were reduced in the presence of serum.     

猪胸膜肺炎放线杆菌、多杀性巴氏杆菌和副猪嗜血杆菌复合PCR检测方法的建立

目的建立可以同时检测猪胸膜肺炎放线杆菌、多杀性巴氏杆菌和副猪嗜血杆菌的快速而可靠的PCR检测方法。方法和结果根据胸膜肺炎放线杆菌的Apx-VIA基因序列、多杀性巴氏杆菌和副猪嗜血杆菌的16SrRNA基因序列设计5条引物。猪胸膜肺炎放线杆菌、多杀性巴氏杆菌和副猪嗜血杆菌模板的PCR扩增产物大小分别为342bp,485bp和1258bp。复合PCR对1～12型猪胸膜肺炎放线杆菌标准株,6株多杀性巴氏杆菌标准株,1～15型副猪嗜血杆菌以及25株经生化鉴定确认为上述三种细菌的分离株的基因组DNA作为模板进行检测,均获得预期大小的扩增产物。以猪放线杆菌、吲哚放线杆菌等14种常见细菌作为阴性对照进行PCR检测,结果仅有支气管败血波氏杆菌产生了可以和上述三个特异性条带明显区分的PCR产物。复合PCR针对胸膜肺炎放线杆菌、多杀性巴氏杆菌和副猪嗜血杆菌的敏感性分别为14pg、34pg和37pg。结论本研究建立的复合PCR特异性好,敏感性高,可以用于猪胸膜肺炎放线杆菌、多杀性巴氏杆菌和副猪嗜血杆菌的快速检测。     

Antimicrobial susceptibility and plasmid analysis of Actinobacillus pleuropneumoniae isolated in Taiwan.

Sixty Actinobacillus pleuropneumoniae (App) strains from pigs in Taiwan were examined. Serotyping revealed that these belonged to serovars 1 (n=53), 2 (n=3), and 5 (n=4). Agar disk diffusion susceptibility testing of the isolates showed 55 (92%) were resistant to three or more antimicrobial agents. Six resistance patterns were observed. Ampicillin-chloramphenicol-flumequine-nalidixic acid-streptomycin-sulfonamide/trimethoprim-tetracycline was the most common multi-resistance pattern. Minimal inhibitory concentration of 14 antimicrobial agents was determined. The isolates were highly susceptible to ceftiofur and trimethoprim in vitro. Isolates were resistant to streptomycin, ampicillin, and nalidixic acid. All isolates were examined for the presence of plasmids using the alkaline lysis method. Forty three (72%) isolates had four plasmid bands with an approximate sizes of 3.5, 4.3, 5.8 and 6.0 kb; 12 (20%) had three bands at 3.5, 4.3 and 5.2 kb, and 5 (8%) had no plasmid bands. Antimicrobial resistance plasmids were detected in resistant strains of App. Three antimicrobial resistance plasmids were transformed into E. coli DH5 alpha. pTMY1 (4.3 kb) encoded a streptomycin kinase and a dihydropteroate synthase; pTMY2 (6.0 kb) encoded ROB-1 beta-lactamase and aminoglycoside 3'-phosphotransferase; pTMY3 (5.2 kb) encoded only ROB-1 beta-lactamase. The 4.3 kb plasmid was sequenced and consisted of 4242 bp with 42.9% GC content. The 4.3 kb plasmid DNA sequence was 98% homologous to a plasmid previously isolated from Pasteurella haemolytica.     

In vitro antimicrobial susceptibility of Pasteurella haemolytica and Pasteurella multocida recovered from cattle with bovine respiratory disease complex

The antimicrobial susceptibilities of 421 Pasteurella haemolytica and 158 P. multocida isolates recovered from cattle with respiratory disease were determined with a microdilution minimal inhibitory concentration test system. Isolates were analyzed for patterns of resistance to ampicillin, ceftiofur, erythromycin, gentamicin, penicillin, spectinomycin, sulfachlorpyridazine, sulfadimethoxine, tetracycline, and tylosin. All isolates tested were found susceptible to ceftiofur and sulfachlorpyridazine. Pasteurella haemolytica isolates were resistant to ampicillin, penicillin, sulfadimethoxine, tetracycline, and tylosin. Pasteurella multocida isolates were resistant to sulfadimethoxine, tetracycline, and tylosin.     

An evaluation of the API ZYM system as a means of identifying Haemophilus somnus and related taxa.

The commercially available API ZYM microbiological identification system was evaluated for the rapid identification of Haemophilus somnus. Eighty-seven isolates of the organism had API ZYM profiles which were characteristic. The API ZYM profiles demonstrate clear differences between H. somnus and other genera but suggest a close association to three related organisms. Enzyme activity of H. somnus isolates were similar to organisms identified as Histophilus ovis, Haemophilus agni and strains UQV of Actinobacillus actinoides and Actinobacillus seminis but was clearly different from isolates of Pasteurella haemolytica, Pasteurella multocida, Bordetella bronchiseptica and group EF4. The API ZYM system allowed more rapid identification of H. somnus than conventional biochemical tests and may be a useful adjunct to conventional methods used for identification of H. somnus isolates. The test did not reveal obvious differences between isolates from various anatomic locations.     

Sequence analysis of the ROB-1 beta-lactamase gene from Actinobacillus pleuropneumoniae.

The ROB-1 beta-lactamase gene from Actinobacillus pleuropneumoniae was cloned and sequenced. The structural gene encodes a 305 amino acid polypeptide. The ROB-1 beta-lactamase gene sequence is identical to that derived from Pasteurella haemolytica and only one amino acid different from that of Haemophilus influenzae, suggesting that they are derived from the same ancestor, and transformed from one to another.     

Changes in the bacterial flora of the upper and lower respiratory tracts and bronchoalveolar lavage differential cell counts in feedlot calves treated for respiratory diseases.

Serial nasopharyngeal swab and bronchoalveolar lavage cultures were used to estimate changes in the bacterial flora of the respiratory tracts of calves during the first month after arrival in the feedlot. Bronchoalveolar lavage (BAL) differential cell counts served to evaluate pulmonary inflammatory changes during this period. Two groups of calves were studied, one consisting of clinically normal controls (n = 60), the other, of cases (n = 59) which received treatment for respiratory disease (penicillin +/- trimethoprimsulfadoxine). A variety of organisms, including Pasteurella multocida, Pasteurella haemolytica, Haemophilus somnus, Mycoplasma bovis and Mycoplasma bovirhinis, were present in the upper and lower airways of both groups during the postarrival period. With the exception of M. bovis, an overall decline in the prevalence of these organisms was observed during the course of the study. In cases, there was a marked decrease in the number of Pasteurella spp. and H. somnus isolates immediately following treatment. For the Pasteurella spp., however, this effect was shortlived as they often appeared to recolonize the respiratory tract within eight days of terminating antimicrobial therapy. Treatment did not appear to affect the frequency of isolating M. bovis. Its prevalence, in both groups of calves, increased to levels approaching 100% during the course of the study. All Pasteurella spp. isolates were tested for susceptibility to several commonly used antimicrobials. Resistance was only evident among P. haemolytica isolated from cases and in every instance this was to a combination of penicillin, ampicillin and tetracycline. Significantly more isolates were resistant after treatment than before. There were BAL differential cell count abnormalities indicative of inflammation in both cases and controls.(ABSTRACT TRUNCATED AT 250 WORDS)     

重组溶葡萄球菌酶对奶牛乳房炎和子宫内膜炎常见病原菌的体外杀菌试验

从患乳房炎和子宫内膜炎奶牛的奶或子宫黏液中分离菌株,鉴定后选取金黄色葡萄球菌105株、表皮葡萄球菌20株、大肠埃希氏菌20株、链球菌38株(其中停乳链球菌8株,无乳链球菌30株)和牛源多杀巴氏杆菌5株,在体外用重组溶葡萄球菌酶、苯唑西林、氨苄西林、庆大霉素按照微量肉汤稀释法进行了杀菌试验。结果表明,重组溶葡萄球菌酶对奶牛乳房炎和子宫内膜炎分离的金黄色葡萄球菌和表皮葡萄球菌具有良好抑杀效果,对链球菌(包括无乳链球菌和停乳链球菌)和牛源多杀巴氏杆菌具有一定的抑杀效果,对大肠杆菌作用较差;苯唑西林、氨苄西林、庆大霉素都有一定量的耐药菌株产生,而重组溶葡萄球菌酶对苯唑西林、氨苄西林、庆大霉素耐药菌株同样具有良好抑杀效果。     

Clavulanic acid-potentiated activity of amoxicillin against Bacteroides fragilis

Seventy-seven clinical isolates of Bacteroides fragilis from animal sources were examined for beta-lactamase production and resistance to amoxicillin. Sixty-five (84%) of the isolates produced detectable amounts of beta-lactamase. Concentrations of amoxicillin greater than 8 micrograms/ml were required to inhibit all but 13 (17%) of the isolates evaluated. Clavulanic acid, a beta-lactamase inhibitor, minimally inhibited growth of B fragilis when used alone. However, a synergistic effect was found when amoxicillin and clavulanic acid were used together against B fragilis. Ninety-nine percent of the isolates were inhibited by concentrations of 1 microgram of amoxicillin/ml in combination with 0.5 microgram of clavulanic acid/ml.     

Plasmid mediated antimicrobial resistance in Ontario isolates of Actinobacillus (Haemophilus) pleuropneumoniae.

The genetic basis of antimicrobial resistance in Ontario isolates of Actinobacillus (Haemophilus) pleuropneumoniae was studied. Two Ontario isolates of A. pleuropneumoniae were found to be resistant to sulfonamides (Su), streptomycin (Sm) and ampicillin (Amp). Resistance to Su and Sm was specified by a 2.3 megadalton (Mdal) plasmid which appeared to be identical to pVM104, which has been described in isolates of A. pleuropneumoniae from South Dakota. Southern hybridization showed that the 2.3 Mdal Su Sm plasmid was highly related to those Hinc II fragments of RSF1010 known to carry the Su Sm genes, but was unrelated to the remainder of this Salmonella resistance plasmid. Resistance to Su and Amp was specified by a 3.5 Mdal plasmid and appeared identical to pVM105 previously reported. The beta-lactamase enzyme had an isoelectric point of approximately 9.0. Southern hybridization showed no relationship to the TEM beta-lactamase. A third isolate of A. pleuropneumoniae was found to be resistant to chloramphenicol (Cm), Su and Sm by virtue of a 3.0 Mdal plasmid which specified a chloramphenicol acetyl transferase. We conclude that resistance to Su, Sm, Amp and Cm is mediated by small plasmids in A. pleuropneumoniae. Although the Su and Sm resistance determinants are highly related to those found in Enterobacteriaceae, the plasmids themselves and the beta-lactamase determinant are different.     

Confirmation that PCR can be used to identify NAD-dependent and NAD-independent Haemophilus paragallinarum isolates.

Seventy five bacteria tentatively identified as Haemophilus paragallinarum (the causative agent of infectious coryza), eight identified as Ornithobacterium rhinotracheale and 13 identified as NAD-independent Pasteurella species were isolated from chickens with respiratory infection in various provinces in South Africa. The isolates were characterized by conventional biochemical and serological methods. A polymerase chain reaction (PCR) assay specific for H. paragallinarum was used to identify the cultures directly from colonies. The PCR assay gave positive results for all isolates that were identified by conventional methods as H. paragallinarum, irrespective of whether they were nicotinamide adenine dinucleotide (NAD)-dependent (43 isolates) or NAD-independent (32 isolates). The eight isolates that were identified by conventional methods as O. rhinotracheale and the 13 isolates identified as various Pasteurella species gave negative results in the PCR assay. This study has demonstrated that colony PCR is a rapid method for uniquely identifying both NAD-dependent and NAD-independent strains of H. paragallinarum and distinguishing them from other bacteria, such as O. rhinotracheale and Pasteurella species.     

Characterization and comparison of antimicrobial susceptibilities and outer membrane protein and plasmid DNA profiles of Pasteurella haemolytica and certain other members of the genus Pasteurella.

The outer membrane protein (OMP), plasmid, and antimicrobial resistance profiles of Pasteurella haemolytica serotypes 1 through 12, a bovine isolate of P multocida, a chicken isolate of P multocida, and an unidentified Pasteurella species of bovine origin were examined. Isolates of P haemolytica serotypes belonging to the same biotype possessed similar OMP profiles. Biotype A isolates contained 2 prominent OMP of 43 kilodaltons (kD) and 29 kD, whereas biotype-T serotypes contained 3 major OMP of 43, 36, and 25 kD. The major OMP profiles of the 2 P multocida isolates and the unidentified Pasteurella species were different from each other and from P haemolytica isolates. Plasmid DNA screening indicated both plasmid-containing and plasmid-free P haemolytica and P multocida isolates. Multiple drug resistance was found in pasteurellae isolates with and without plasmids. However, a relationship between drug resistance and plasmid isolation was found in 3 of 4 haemolytica serotype 1 field isolates, all of which contained a 2.51-megadalton plasmid and had multiple drug resistance for benzylpenicillin, ampicillin, streptomycin, and tetracycline.