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1.
Paenibacillus larvae is the causal agent of American Foulbrood (AFB) disease, the most virulent bacterial disease of honeybee (Apis mellifera L.) brood. Oxytetracycline is the main antibiotic used for prevention and control of AFB. Using the polymerase chain reaction, isolates were screened for the presence of the tetracycline resistance tet(K) and tet(L) determinants. Four isolates (5%), which correlated with the Tc-resistant phenotypes, were found to carry the tet(K) determinant, whereas none carried the tet(L) determinant. P. larvae cells were also screened for the presence of extrachromosomal DNA and evidence obtained that tetracycline resistance is plasmid-encoded. A few P. larvae isolates were found to be able to transfer the tet(K) determinant to Bacillus subtilis, suggesting that a conjugation mechanism may be involved in the transfer of the tetracycline-resistant phenotype. Minimum inhibitory concentrations to tetracycline were determined for 75 isolates of P. larvae from different geographical origins and found to range between 0.062 and 128 microg tetracyclineml(-1), with MIC(50) and MIC(90) values of 1 and 4, respectively. According to results from P. larvae populations, isolates could be considered as susceptible when their MICs were <4, intermediate for MICs values 4-8 and resistant for MICs > or = 16. To our knowledge, this is the first report of Tc(r)Paenibacillus species carrying a tet(K) gene, and also the first record of P. larvae strains carrying tet(K) determinants and its correlation with the presence of extrachromosomal DNA.  相似文献   

2.
Paenibacillus larvae is the causative agent of American Foulbrood (AFB), a severe disease that affects larvae of the honeybees. Due to the serious effects associated with AFB and the problems related to the use of antibiotics, it is necessary to develop alternative strategies for the control of the disease. The aim of the present work was to evaluate the effect of a propolis ethanolic extract (PEE) against P. larvae and its potential for the control of AFB. In vitro activity of PEE against P. larvae isolates was evaluated by the disk diffusion method and the minimum inhibitory concentration (MIC) was determined. Toxicity for honeybees was evaluated by oral administration of PEE and its lethal concentration was assessed. Lastly, colonies from an apiary with episodes of AFB on previous years were divided into different groups and treated with sugar syrup supplemented with PEE by aspersion (group one), sugar syrup by aspersion (group two), fed with sugar syrup supplemented with PEE (group three) and fed with sugar syrup only (group four). All isolates were sensitive to PEE and the MIC median was 0.52% (range 0.32-0.64). PEE was not toxic for bees at least at 50%. Field assays showed that 21 and 42 days after the application of the treatments, the number of P. larvae spores/g of honey was significantly lower in colonies treated with PEE compared to the colonies that were not treated with PEE. To our knowledge, this is the first report about the use of propolis for the treatment of beehives affected with P. larvae spores.  相似文献   

3.
Cross-reactivity indices (CRIs) of 28 isolates of Moraxella bovis recovered from outbreaks of infectious bovine keratoconjunctivitis in Argentina (A, 11 isolates), Brazil (B, 7), and Uruguay (U, 10) between 1983 and 2000 were estimated. Hyperimmune sera were produced in rabbits and antibody titres determined with each isolate. Isolates showing CRIs3 70 were placed in the same group. Group I had 13 isolates (A, 1; B, 6; U, 6); group II had 6 isolates (A, 4; U, 2); groups III, IV, and V had 2 isolates each, recovered in Argentina; group VI had 2 isolates, from Uruguay; and group VII had 1 isolate, from Brazil. The CRIs3 70 between vaccine strains and isolates recovered before and after 1990 were 58% and 42%, 50% and 50%, and 33% and 67% with vaccine strains 2419, 2358, and 2439, respectively. Isolate 273, from Uruguay, showed CRIs > 70 with 78% of the isolates and is recommended as the vaccine strain.  相似文献   

4.
OBJECTIVES: To assess automated ribotyping for characterization of Pseudomonas aeruginosa isolates and to identify their type prevalence and geographic distribution. SAMPLE POPULATION: 39 human and 56 ruminant P aeruginosa isolates. PROCEDURES: Isolates were identified by use of bacteriologic techniques and automated Pvull-based ribotyping. Susceptibility to antimicrobials was tested in vitro. Data were analyzed for index of discrimination; prevalence ratio; geographic distribution of ribotypes found only in humans, only in cows, or only in goats (single-host ribotypes); and geographic distribution of ribotypes found in humans and ruminants (multihost ribotypes). RESULTS: All isolates were typeable (45 ribotypes, 35 single-host ribotypes). Ribotyping index of discrimination was 0.976. More isolates (45.3%) than expected yielded multihost ribotypes (22% of all ribotypes). Although 8.6% of single-host ribotypes were found in 4 or more isolates, 60% of multihost ribotypes were found in 4 or more isolates. Ninety percent of multihost ribotypes were isolated from different geographic areas, whereas 3.0% of single-host ribotypes were isolated from different geographic areas. All ruminant isolates were susceptible to gentamicin and polymyxin B. In contrast, antibiogram profiles differed for human isolates from different geographic areas. Susceptibility to antimicrobials differentiated 6 isolates not distinguished by ribotyping. CONCLUSIONS AND CLINICAL RELEVANCE: Automated ribotyping with Pvull discriminated more isolates than in vitro antimicrobial susceptibility. In combination, both tests provided more information than either test alone. Given the greater prevalence and geographic distribution of multihost ribotypes, immunocompromised humans and lactating ruminants may have a greater risk for disease if exposed to multihost P aeruginosa ribotypes, compared with single-host ribotypes.  相似文献   

5.
Thirty‐one Salmonella Enteritidis strains isolated from chickens, broilers and hens were analysed by genotypic typing including REP‐PCR, ERIC‐PCR and ITS profiling (PCR‐ribotyping). Analysis of DNA banding patterns generated by REP‐PCR revealed the presence of 22 different genotypes, which were grouped by dendrogram analysis into three distinct lineages (maximum similarity approx. 50%). Each isolate of S. Enteritidis analysed by ERIC‐PCR generated an individual DNA pattern. Again, these isolates could be divided into three distinct genomic groups (maximum similarity approx. 60%) by their ERIC‐PCR fingerprints. REP‐ and ERIC‐PCR were found to be more discriminatory for typing of S. Enteritidis than ITS profiling. Amplification of the 16S‐23S rDNA spacer region gave nine different profiles of DNA, subdivided into two closely related groups by dendrogram analysis. In summary, data obtained by genotyping methods for S. Enteritidis isolates from regions located in the south‐west and the central parts of Poland revealed an enormous heterogeneity among analysed samples, and proved that REP‐ and ERIC‐PCR are highly discriminatory techniques, which can be used, in addition to conventional methods, in epidemiological studies of S. Enteritidis infections.  相似文献   

6.
We analysed 251 early spring and winter storage honey samples, individually collected from the apiaries of 9 districts of Malopo?ska province in South Poland and revealed that 51 of these specimens were contaminated with different levels of P. larvae larvae spores Among these samples 8.8% were classified as a category I contamination and 11.5% as a category II--reperesenting 22 (43.1%) and 29 (56.9%) of the total positives, respectively. We conclude from these analyses that: (1)--the total number of new outbreaks of AFB in Poland are most likely to be higher than previously reported, (2)--the quantitative examination of samples of winter stored or early spring honeys for the presence of P. larvae, larvae spores can improve the detection rate of AFB outbreaks, (3)--the high percentage of apiaries that were found to be free of P. larvae larvae (80%) may facilitate the implementation of an AFB eradication programme on a large scale in Poland.  相似文献   

7.
We studied the ribotypes, patterns of pulsed-field gel electrophoresis (PFGE) and interspersed repeated sequences (IRS)-PCR of 30 strains of Yersinia ruckeri O1 and 20 strains of Photobacterium damsela subsp. piscicida isolated from apparently unrelated epizootic outbreaks occurring on Italian fish farms between 1993 and 1999. All of the Y. ruckeri O1 strains had similar profiles, as demonstrated by all three typing methods, thus confirming the clonal structure of this species. The strains of P. damsela subsp. piscicida showed similar profiles when tested with ribotyping and PFGE; however, two slightly different profiles were distinguished by IRS-PCR using the primer ERIC2. The two profiles appeared to be related to the geographic origin of the strains, since each of them was specific to isolates from a certain area (i.e. northern or southern Italy). This result suggests that PCR fingerprinting may be a valuable tool in typing fish bacterial pathogens, which often present a great degree of genetic homogeneity.  相似文献   

8.
Clinical isolates (n = 63) of Pseudomonas aeruginosa obtained from various sites in 63 horses were compared using ERIC2 RAPD PCR to determine their genetic relatedness. Resulting banding patterns (n = 24 genotypes) showed a high degree of genetic heterogeneity amongst all isolates examined, indicating a relative non-clonal relationship between isolates from these patients, employing this genotyping technique. This study characterised 63 clinical isolates into 24 distinct genotypes, with the largest cluster (genotype E) accounting for 10/63 (15.9%) of the isolates. ERIC2 RAPD PCR proved to be a highly discriminatory molecular typing tool of P. aeruginosa in isolates recovered from horses. With the adoption of several controls to aid reproducibility, this technique may be useful as an alternative to PFGE, particularly in epidemiological investigations of outbreaks where speed may be a significant parameter. This is the first report of clonal heterogeneity amongst P. aeruginosa from horses and demonstrated that ERIC RAPD PCR is a rapid method for the examination of this species in horses, which may be useful in outbreak analysis.  相似文献   

9.
A total of 60 Staphylococcus intermedins strains from dogs were investigated by their sensitivity to various antibiotics (50 strains) and by their rRNA gene restriction patterns (ribotyping) (60 strains). Fifteen isolates were from healthy dogs, 9 with otitis externa, and 36 with pyoderma, including 10 strains from a previous study. Sixty per cent of the 50 strains tested for antibiotic susceptibility demonstrated resistance to penicillin, 24% to spiramycin, 20% to tetracycline, 16% to chloramphenicol, and 2% to fucidic acid. All isolates were susceptible to amoxycillin with clavulanic acid, enrofloxacin, and sulphonamides with trimethoprim. There were no significant differences in antimicrobial susceptibility patterns observed among isolates from pyoderma, otitis externa or healthy dogs. Among the 60 strains studied by ribotyping, 10 different ribotypes were identified: 6 different ribotypes among isolates from otitis externa, 8 among isolates from pyoderma, and 5 among isolates from healthy dogs. One ribotype (profile C) was dominant among the isolates from healthy dogs while another ribotype (profile A) was dominant among strains from dogs suffering from pyoderma. This profile was not demonstrated in any of the strains from healthy dogs. From 5 different dogs suffering from pyoderma, 2 different clones were demonstrated based on their plasmid profile and antibiogram. In these dogs 1 of the clones always belonged to ribotype A. The results concerning strains of S. intermedins isolated from furunculosis suggest the existence of distinct subpopulations with different pathogenicity to dogs.  相似文献   

10.
The aim of the present study was to evaluate capsular-typing, plasmid-profiling, phage-typing and ribotyping for epidemiological studies of toxin-producing Pasteurella multocida ssp. multocida in Denmark. The evaluation of methods was based on 68 strains from nasal swabs and 14 strains from pneumonic lungs. Strains from lungs were all of capsular Type A, whereas strains from nasal swabs were of both capsular Types A and D. Only 9% of the strains contained plasmids, which could not be associated with antibiotic resistance. Phage-typing divided 61% of strains into 10 groups, while 39% were non-typable. CfoI ribotyping divided strains into four groups of which one type contained 94% of isolates. HindIII ribotyping divided strains into 18 types. A total of 18 strains from The Netherlands, UK and USA were subjected to HindIII ribotyping, resulting in 13 types of which six were identical to ribotypes of Danish strains. Phage-typing of isolates from an outbreak of atrophic rhinitis involving six herds in 1985 showed the existence of an epidemic strain. This type was recognised in the herd suspected of being the source of the infections and in four of the five infected herds. These findings were supported by HindIII ribotyping, as 85% of isolates from all herds were assigned to one ribotype. In conclusion, HindIII ribotyping seems to represent a useful tool for epidemiological studies of toxigenic P. multocida ssp. multocida.  相似文献   

11.
REASONS FOR PERFORMING STUDY: Bacterial ulcerative keratitis is a common and often vision-threatening problem in horses. Emerging bacterial resistance to commonly used topical antibiotics has been demonstrated. Previous antibiotic use may alter the antimicrobial susceptibility of bacterial isolates. OBJECTIVES: To document aerobic bacterial isolates and associated bacterial susceptibilities from horses with ulcerative keratitis treated at the University of Tennessee between January 1993 and May 2004 and determine whether prior antibiotic therapy affected antimicrobial susceptibility of the isolates. METHODS: Medical records from horses with ulcerative keratitis and positive aerobic bacterial cultures and antimicrobial susceptibility were evaluated. Clinical history regarding antibiotic therapy prior to culture was documented. RESULTS: Fifty-one aerobic bacterial isolates from 43 horses were identified. Streptococcus equi subspecies zooepidemicus was the most commonly isolated organism, accounting for 33.3% of all isolates, followed by Pseudomonas aeruginosa (11.8%), Staphylococcus spp. (11.8%) and Gram-negative nonfermenting rods (7.8 %). No resistance was noted amongst S. equi ssp. zooepidemicus to cephalothin, chloramphenicol or ciprofloxacin. Only 64 % of S. equi ssp. zooepidemicus isolates were sensitive to bacitracin. No resistance was noted among P. aeruginosa to gentamicin, tobramycin or ciprofloxacin. Antibiotic therapy with neomycin-polymixin B-bacitracin prior to presentation and culture was documented in 11/17 horses in which S. equi ssp. zooepidemicus was isolated and in 4/6 horses in which P. aeruginosa was isolated. Three horses received topical corticosteroids prior to culture, of which 2 had polymicrobial infections. CONCLUSIONS: S. equi ssp. zooepidemicus and P. aeruginosa were the most frequently isolated bacterial organisms in equine ulcerative keratitis. No significant trends in aminoglycoside or fluoroquinolone resistance were noted among these organisms. However, the resistance of S. equi ssp. zooepidemicus to bacitracin with common use of this antibiotic suggests that previous antibiotic therapy probably affects antimicrobial resistance. POTENTIAL RELEVANCE: Therapy prior to culture may play an important role in antimicrobial susceptibility of corneal bacterial isolates. Corticosteroid use may increase the risk of polymicrobial infections of corneal ulcers, leading to a worse prognosis. Although significant fluoroquinolone resistance has not been documented in the veterinary literature, these antimicrobials should be reserved for known infected corneal ulcers and not used for prophylaxis. Empirical antibiotic therapy should not only be guided by clinical signs, but also take into consideration previous antimicrobial and corticosteroid therapy.  相似文献   

12.
Paenibacillus larvae is a gram-positive spore-forming bacteria, causative agent of American Foulbrood (AFB), a severe disease affecting larvae of the honeybee Apis mellifera. In an attempt to detect potential virulence factors secreted by P. larvae, we identified an enolase among different secreted proteins. Although this protein is a cytosolic enzyme involved in glycolytic pathways, it has been related to virulence. The aim of the present work was to evaluate its role during the infection of honeybee larvae. Toxicity assays showed that enolase was highly toxic and immunogenic to honeybee larvae. Its production was detected inside P. larvae vegetative cells, on the surface of P. larvae spores and secreted to the external growth medium. P. larvae enolase production was also confirmed in vivo, during the infection of honeybee larvae. This protein was able to hydrolyze milk proteins as described for P. larvae, suggesting that could be involved in larval degradation, maybe through the plasmin(ogen) system. These results suggest that P. larvae enolase may have a role in virulence and could contribute to a general insight about insect-pathogen interaction mechanisms.  相似文献   

13.
Biochemical profiles, restriction endonuclease analysis (REA) and ribotyping were used to investigate a total of 38 Pasteurella multocida isolates from four separate outbreaks of pasteurellosis in Australian piggeries. Six isolates were obtained from Outbreak 1, 16 from Outbreak 2 and eight each from outbreaks 3 and 4. Outbreaks 1 and 2 were cases of pneumonic pasteurellosis while outbreaks 3 and 4 involved systemic pasteurellosis. Biochemical characterisation established that a number of different types of P. multocida were present in outbreaks 1 and 3 while outbreaks 2 and 4 were associated with a single type of P. multocida. Outbreaks 1 and 3 yielded isolates of P. multocida that belonged to the subspecies multocida and gallicida, with the subspecies multocida isolates being identified as biovar 3 (6 in total) or 12 (1 in total) and the subspecies gallicida isolates (7 in total) being identified as biovar 8. All 24 isolates from outbreaks 2 and 4 belonged to the subspecies multocida and were all biovar 3. REA and ribotyping showed that, in outbreaks 1 and 3, there were three different types of P. multocida in each outbreak with no common strains between the outbreaks. The molecular methods showed that only a single strain of P. multocida was associated with outbreaks 2 and 4, although the outbreaks were associated with strains that differed in REA profiles but shared a ribotype profile. This study has shown that both, systemic and pneumonic pasteurellosis can be associated with either a single strain or multiple strains of P. multocida. The results also indicate that the molecular typing methods of REA and ribotyping are superior to biochemical characterisation for epidemiological investigation of porcine pasteurellosis.  相似文献   

14.
The relatedness of 41 isolates of Salmonella of a novel serotype (antigenic formula 4,12:a:-) of serogroup B, obtained from harbour porpoises (Phocoena phocoena) stranded at various sites around the coastline of Scotland, was assessed by two molecular typing methods. Ribotyping showed that these isolates belonged to seven EcoRI (E) ribotypes and 11 PstI (P) ribotypes that were, in each case, distinct but closely related. Combined ribotyping data identified 15 different E/P ribotypes, the most common of which, E1/P1, was represented by 15 isolates from 14 animals stranded on both east and west coastlines. Strain discrimination achieved by E/P ribotyping was high (D=0.84). IS200 profiling revealed only three different fingerprints and strain discrimination by this method alone was poor (D=0.39). When E/P ribotyping and IS200 profiling were used together, they revealed the existence of 17 different types among the 41 isolates which formed two distinct, but related, groups of Salmonella serotype 4,12:a:-. This information should prove helpful in future studies examining the mode of transmission of this novel salmonella serotype and its association with disease in harbour porpoises.  相似文献   

15.
SUMMARY: Biochemical profiles, restriction endonuclease analysis (REA) and ribotyping were used to investigate Pasteurella multocida isolates from outbreaks of fowl cholera on 7 turkey farms in New South Wales. While only a single isolate was available from 5 of the farms, multiple isolates, 4 and 12 respectively, were available from the other 2 farms. The available field evidence suggested that 8 outbreaks had occurred with one farm suffering 2 outbreaks. The isolates obtained were all confirmed as Pasteurella multocida . Biochemical profiles allocated the isolates to 4 groups, 3 being variants of P multocida subsp multocida and the fourth being P multocida subsp septica . REA performed with Hpall established 7 groups. Ribotyping using the Hpall digests probed with the 16S rRNA operon of Haemophilus paragallinarum recognised the same 7 groups as REA. Unlike the biochemical profiles, both REA and ribotyping provided a fine subdivision that identified outbreaks as either related or unrelated. The REA and ribotyping patterns as well as biochemical profiles were stable for all isolates from the outbreaks in which multiple isolates were obtained from either the same bird or from different birds. REA and ribotyping were found to be superior to biotyping methods for the investigation of fowl cholera outbreaks.  相似文献   

16.
Prevalence of ocular microorganisms in hospitalized and stabled horses   总被引：2，自引：0，他引：2  
Microorganisms from normal eyes of hospitalized and stabled horses were identified, and the frequency of isolation was compared between the 2 groups. Using standard techniques, swab specimens from both eyes of 22 hospitalized horses and both eyes of 18 stabled horses were cultured for aerobic bacteria and fungi. Ninety-six aerobic bacteria and 57 fungi were isolated. The predominant bacterial isolates were gram-positive organisms, most of which belonged to the genera Corynebacterium, Bacillus, Staphylococcus, and Streptomyces. Gram-negative organisms comprised less than one-fourth of the bacterial isolates, with the genera Neisseria, Moraxella, and Acinetobacter being the most commonly isolated. Environmental fungi Cladosporium and Alternaria accounted for half of all fungal isolates. In only 5 horses were fungi isolated without accompanying isolation of bacteria. The frequency of isolation of fungi was higher (P less than 0.01) in stabled horses. For bacteria, the frequency of isolation was higher (P less than 0.08) in male horses. Results of susceptibility testing were recorded as the percentage of all isolates susceptible to a given antimicrobic drug. Bacterial isolates were highly susceptible (greater than or equal to 90%) to neomycin, polymixin B, gentamicin, and chloramphenicol. Overall, filamentous fungi had highest susceptibility to natamycin (97%). Miconazole was highly efficacious (100% susceptibility) against Fusarium and Aspergillus.  相似文献   

17.
DNA sequences of Amblyomma aureolatum (Pallas, 1772) and Amblyomma ovale Koch, 1844 were obtained to determine genetic differences between these tick species. Collections of these species are discussed in relation to distribution and hosts. Seven ticks collections (four from Brazil, one from Argentina, one from Uruguay and one from USA) house a total of 1272 A. aureolatum (224 males, 251 females, 223 nymphs and 574 larvae) and 1164 A. ovale (535 males, 556 females, 66 nymphs and 7 larvae). The length of the sequenced mitochondrial 16S rRNA gene fragment for A. aureolatum was 370bp and for A. ovale was 373bp. The DNA sequence analysis showed a 13.1% difference between the two species. Apart from one male A. ovale found on a toad, all adult ticks were found on mammals. The majority of adult specimens of both tick species were removed from Carnivora (96.1 and 84.3% of A. aureolatum and A. ovale, respectively), especially from dogs (53.1% of A. aureolatum, and 46.4% of A. ovale). Collections on wild Canidae were higher for A. aureolatum (23.3%) than for A. ovale (7.1%). On the other hand, collections of A. ovale adults on wild Felidae were higher (18.3%) than findings of A. aureolatum (9.2%). The contribution of other mammalian orders as hosts for adults of A. aureolatum and A. ovale was irrelevant, with the exception of Perissodactyla because Tapiridae contributed with 13.0% of the total number of A. ovale adults. Adults of both tick species have been found occasionally on domestic hosts (apart of the dog) and humans. Most immature stages of A. aureolatum were found on Passeriformes birds, while rodents and carnivores were the most common hosts for nymphs and larvae of A. ovale. A. aureolatum has been found restricted to the Neotropical region, covering the eastern area of South America from Uruguay to Surinam, including northeastern Argentina, eastern Paraguay, southeastern Brazil and French Guiana. A. ovale showed a distribution that covers the Neotropical region from central-northern Argentina throughout the Neotropics into the Nearctic region of Mexico with a few records from the USA, also with collection sites in Paraguay, Bolivia, most Brazilian states, Peru, Ecuador, French Guiana, Surinam, Guyana, Trinidad & Tobago, Venezuela, Colombia, Panama, Costa Rica, Nicaragua, Belize, Guatemala and several states of Mexico.  相似文献   

18.
American Foulbrood (AFB) of honeybees (Apis mellifera L.), caused by the Gram-positive bacterium Paenibacillus larvae is one of the most serious diseases affecting the larval and pupal stages of honeybees (A. mellifera L.). The aim of the present work was to asses the response of 23 strains of P. larvae from diverse geographical origins to tilmicosin, a macrolide antibiotic developed for exclusive use in veterinary medicine, by means of the minimal inhibitory concentration (MIC) and the agar diffusion test (ADT). All the strains tested were highly susceptible to tilmicosin with MIC values ranging between 0.0625 and 0.5 microg ml(-1), and with MIC(50) and MIC(90) values of 0.250 microg ml(-1). The ADT tests results for 23 P. larvae strains tested showed that all were susceptible to tilmicosin with inhibition zones around 15 microg tilmicosin disks ranging between 21 and 50mm in diameter. Oral acute toxicity of tilmicosin was evaluated and the LD(50) values obtained demonstrated that it was virtually non-toxic for adult bees and also resulted non-toxic for larvae when compared with the normal brood mortality. Dosage of 1000 mg a.i. of tilmicosin applied in a 55 g candy resulted in a total suppression of AFB clinical signs in honeybee colonies 60 days after initial treatment. To our knowledge, this is the first report of the effectiveness of tilmicosin against P. larvae both in vitro and in vivo.  相似文献   

19.
OBJECTIVE: To describe antimicrobial susceptibility testing practices of veterinary diagnostic laboratories in the United States and evaluate the feasibility of collating this information for the purpose of monitoring antimicrobial resistance in bacterial isolates from animals. DESIGN: Cross-sectional study. PROCEDURES: A questionnaire was mailed to veterinary diagnostic laboratories throughout the United States to identify those laboratories that conduct susceptibility testing. Nonrespondent laboratories were followed up through telephone contact and additional mailings. Data were gathered regarding methods of susceptibility testing, standardization of methods, data management, and types of isolates tested. RESULTS: Eighty-six of 113 (76%) laboratories responded to the survey, and 64 of the 86 (74%) routinely performed susceptibility testing on bacterial isolates from animals. Thirty-four of the 36 (94%) laboratories accredited by the American Association of Veterinary Laboratory Diagnosticians responded to the survey. Laboratories reported testing > 160,000 bacterial isolates/y. Fifty-one (88%) laboratories reported using the Kirby-Bauer disk diffusion test to evaluate antimicrobial susceptibility; this accounted for 65% of the isolates tested. Most (87%) laboratories used the NCCLS (National Committee for Clinical Laboratory Standards) documents for test interpretation. Seventy-five percent of the laboratories performed susceptibility testing on bacterial isolates only when they were potential pathogens. CONCLUSIONS: The veterinary diagnostic laboratories represent a comprehensive source of data that is not easily accessible in the United States. Variability in testing methods and data storage would present challenges for data aggregation, summary, and interpretation.  相似文献   

20.
Pasteurella multocida and bovine respiratory disease   总被引：1，自引：0，他引：1  
Pasteurella multocida is a pathogenic Gram-negative bacterium that has been classified into three subspecies, five capsular serogroups and 16 serotypes. P. multocida serogroup A isolates are bovine nasopharyngeal commensals, bovine pathogens and common isolates from bovine respiratory disease (BRD), both enzootic calf pneumonia of young dairy calves and shipping fever of weaned, stressed beef cattle. P. multocida A:3 is the most common serotype isolated from BRD, and these isolates have limited heterogeneity based on outer membrane protein (OMP) profiles and ribotyping. Development of P. multocida-induced pneumonia is associated with environmental and stress factors such as shipping, co-mingling, and overcrowding as well as concurrent or predisposing viral or bacterial infections. Lung lesions consist of an acute to subacute bronchopneumonia that may or may not have an associated pleuritis. Numerous virulence or potential virulence factors have been described for bovine respiratory isolates including adherence and colonization factors, iron-regulated and acquisition proteins, extracellular enzymes such as neuraminidase, lipopolysaccharide, polysaccharide capsule and a variety of OMPs. Immunity of cattle against respiratory pasteurellosis is poorly understood; however, high serum antibodies to OMPs appear to be important for enhancing resistance to the bacterium. Currently available P. multocida vaccines for use in cattle are predominately traditional bacterins and a live streptomycin-dependent mutant. The field efficacy of these vaccines is not well documented in the literature.  相似文献   

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