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D C Hirsh

Publications and source records attributed to D C Hirsh.

At least 37 records · Page 2Linked to original sources
PubMed1996

Distribution of tet(H) among Pasteurella isolates from the United States and Canada.

Tetracycline-resistant isolates of Pasteurella multocida and Pasteurella haemolytica obtained from various locations in the United States and Canada were studied to determine the distribution of the tet(H) gene. Of the 31 isolates examined, 25 were found to contain the tet(H) gene. Chromosomal or plasmid DNA obtained from those that did not contain the tet(H) gene did not hybridize with probes specific for classes A through G, though chromosomal DNA from one isolate lacking tet(H) hybridized with a probe specific for class M. The tet(H) gene was found on plasmid as well as on chromosomal DNA, suggesting that it is carried on a transposable element.

Animals↗
PubMed1995

Cloning and sequence of the groESL heat-shock operon of Pasteurella multocida.

By using degenerate oligodeoxyribonucleotide primers for conserved regions of groEL, a 0.6-kb fragment of Pasteurella multocida genomic DNA was amplified using PCR. The amplified fragment was then used as a probe to isolate a genomic fragment containing the entire GroESL operon. The isolated genomic fragment was found to contain two open reading frames, the sequences of which were highly homologous to the prokaryotic groES and groEL families of genes.

Amino Acid Sequence↗
PubMed1995

Pasteurella multocida produces a protein with homology to the P6 outer membrane protein of Haemophilus influenzae.

An antibody specific for a 16-kDa outer membrane protein of a rabbit strain of Pasteurella multocida was used to probe representatives of all 16 somatic serotypes of P. multocida, as well as the vaccine strains CU and M9, and all were shown to express the protein. The gene encoding this protein was cloned and sequenced and found to have extensive sequence homology with the gene encoding the P6 protein of Haemophilus influenzae. The protein in P. multocida has been designated P6-like. The gene encoding the P6-like protein was used to probe members of the family Pasteurellaceae and other gram-negative bacteria. Representatives of all 16 somatic serotypes (as well as the vaccine strains CU and M9) of P. multocida hybridized with the P6-like gene under conditions of high stringency. The DNA from H. influenzae hybridized weakly with the P6-like gene under these conditions, but Pasteurella haemolytica (representatives of A and T biotypes), Bordetella bronchiseptica, B. avium, Actinobacillus suis, A. suis-like, A. lignieresii, A. ureae, A. rossii, A. pleuropneumoniae, A. equuli, and various members of the family Enterobacteriaceae (Escherichia coli, Klebsiella pneumoniae, and Salmonella typhimurium) did not hybridize detectably. Under conditions of lower stringency, the P6-like gene also hybridized strongly with DNA from P. multocida, H. influenzae, and A. rossii but weakly with DNA from P. haemolytica and members of the genus Actinobacillus. These results suggest that the P6-like protein of P. multocida might be useful as an immunizing product to protect poultry from avian cholera. This suggestion stems from (i) our finding that the P6-like protein in P. multocida is widely distributed among all the somatic serotypes and (ii) the previous work of others demonstrating that the P6 protein of H. influenzae elicits a protective immune response in animal models of human disease.

Amino Acid Sequence↗
PubMed1995

Apparent outbreaks of Clostridium difficile-associated diarrhea in horses in a veterinary medical teaching hospital.

Intestinal colonization with toxigenic strains of Clostridium difficile was documented in 9 of 10 horses with acute onset diarrhea in a veterinary medical teaching hospital, whereas a similar isolate was detected in only 1 of 23 other horses without diarrhea in the hospital. One horse with diarrhea was infected simultaneously with both C. difficile and Salmonella krefeld. Clostridium difficile was detected by fecal culture on selective medium, confirmed with a latex particle agglutination test, and identified as toxigenic by polymerase chain reaction amplification of toxin A and toxin B gene sequences. Using an arbitrarily-primed polymerase chain reaction, 6 distinct C. difficile isolates were detected in the feces of the 9 affected horses at the time of the outbreak of diarrhea.

Animals↗
PubMed1994

Pasteurella multocida produces heat shock proteins in turkeys.

Pasteurella multocida produces an acute septicemic disease of turkeys. Since turkeys have a normal body temperature of 42 degrees C, it follows that P. multocida would produce heat shock proteins during the course of the infectious process. We show here that P. multocida produces several proteins at 42 degrees C, but not at 32 degrees C, and vice versa. Four of these proteins (70, 60, 40, and 35 kDa in molecular mass) were recognized by serum obtained from a turkey infected with P. multocida, suggesting that they were produced in vivo.

Animals↗
PubMed1994

Characterization, distribution, and microbiological associations of Fusobacterium spp. in clinical specimens of animal origin.

During the years from 1984 through 1991, 1,067 specimens from canine, equine, exotic, feline, porcine, and ruminant animal sources were found to contain members of the genus Fusobacterium: The most common sites or conditions from which members of this genus were isolated were abscesses, the respiratory tract, and pleural and peritoneal cavities. Most specimens contained a single Fusobacterium species. The most commonly isolated species was Fusobacterium necrophorum. Almost all of the specimens contained other obligate anaerobes together with facultative and obligate aerobes. The identities of the other isolates depended upon the species of animal from which the sample was obtained.

Abscess↗
PubMed1993

Characteristics of Escherichia coli isolated from septic foals.

Fifteen Escherichia coli isolates from the blood and tissue of foals with septicemia were compared with 15 from the feces of clinically normal horses. Comparisons were made with respect to survival in normal equine serum, production of aerobactin, and production of hemolysin. Isolates from the blood and tissues of septic foals were more likely to be resistant to equine serum than were isolates from feces of clinically normal horses. There were minimal differences between the isolates with respect to aerobactin and hemolysin production, almost all being nonhemolytic and aerobactin negative. Serum resistance is probably a virulence determinant for invasive E. coli in horses.

Animals↗
PubMed1993

A new tetracycline resistance determinant, Tet H, from Pasteurella multocida specifying active efflux of tetracycline.

The tetracycline resistance determinant on plasmid pVM111 from an avian strain of Pasteurella multocida mediates tetracycline resistance by a regulated active efflux mechanism. DNA coding for the determinant did not hybridize at high stringency with DNA representing a group of common tetracycline resistance determinants. The DNA sequence, however; revealed a structural gene and a repressor gene which had significant (37 to 64%) sequence similarities with previously described classes of efflux-type tetracycline resistance genes from members of the family Enterobacteriaceae. The new determinant has been assigned to class H.

Amino Acid Sequence↗
PubMed1993

Use of random fragments of chromosomal DNA to highlight restriction site heterogeneity for fingerprinting isolates of Salmonella typhimurium from hospitalized animals.

Random fragments of DNA were obtained from a cosmid library of Salmonella agona genomic DNA. From this library, 2 fragments were chosen and pooled to probe isolates of S typhimurium obtained during an episode of salmonellosis in a veterinary medical teaching hospital. Chromosomal DNA from the Salmonella isolates was digested with restriction endonucleases, and was probed with the random fragments of chromosomal DNA. This procedure resulted in a fingerprint pattern for each isolate. We found that the method permitted discrimination between isolates involved in the disease episode and S typhimurium obtained prior to the episode. We conclude that random fragments of chromosomal DNA are useful for fingerprinting isolates of S typhimurium. Analysis of plasmid DNA obtained from the isolates was not as useful. Some isolates found to be identical by restriction site analysis, had plasmids of different molecular weight. These results indicate that plasmid analysis may not be as useful a fingerprinting tool as previously reported.

Animals↗
PubMed1993

Linkage of serum resistance, aerobactin production, and resistance to antimicrobial agents on conjugal plasmids in some strains of Escherichia coli isolated from septic foals.

Fifteen isolates of Escherichia coli obtained from the blood and tissues of septic foals had plasmid DNA of size ranging from 2.5 to 93 megadaltons. These isolates grew in normal equine serum (serum resistant), a trait previously documented to be expressed by isolates obtained from blood and tissues of septic foals, but not by isolates obtained from the feces of clinically normal horses. Of these isolates, 3 contained conjugal plasmids that encoded resistance to multiple antimicrobial agents linked to serum resistance and, in 1 isolate, to production of aerobactin as well. Serum resistance and production of aerobactin are related to virulence of septicemic E coli from non-equine sources.

Animals↗
PubMed1992

Tissues and exudates contain sufficient thymidine for growth of anaerobic bacteria in the presence of inhibitory levels of trimethoprim-sulfamethoxazole.

Obligate anaerobes are susceptible in vitro to trimethoprim-sulfonamides. Clinical efficacy of this drug combination for treatment of infectious processes in which anaerobes are involved is uncertain. We hypothesize that this uncertainty is a result of thymidine in tissues and exudates which abrogates the inhibitory effect of trimethoprim-sulfonamides. We shown herein that species of anaerobic bacteria commonly encountered in infectious processes grew on thymidine-containing medium despite the presence of levels of trimethoprim-sulfamethoxazole (S x T) previously shown to be inhibitory. Biologic fluids and tissues, where anaerobic bacteria are commonly encountered in diseased states, were shown to contain thymidine levels that were sufficient to reverse the inhibitory effect of S x T upon these species of bacteria. These observations suggest that the use of trimethoprim-sulfonamides is not a rational choice for treatment of infectious processes in which an obligate anaerobe is a component.

Animals↗
PubMed1992

Enrofloxacin treatment of long-tailed macaques with acute bacillary dysentery due to multiresistant Shigella flexneri IV.

Thirty-four cases of acute bacillary dysentery occurred within 90 days among macaques housed at the California Regional Primate Research Center. Cases were identified by depression, diarrhea with blood and leukocytic exudate, and/or leukocytosis with a left shift. Antimicrobial susceptibility testing of enteric isolates and plasmid profile analyses established an etiologic diagnosis of multiple antibiotic resistant Shigella flexneri IV infection. When standard therapies were invalidated by high frequencies of resistance among the isolates, therapy with enrofloxacin, a fluoroquinolone antimicrobial, was initiated to interrupt the epidemic. Serum concentrations of enrofloxacin and its primary metabolite ciprofloxacin were measured in selected cases. A serum concentration-time data analysis was performed to evaluate the oral enrofloxacin dose and dosing interval for nonfasted macaques. Once daily administration of 5 mg/kg enrofloxacin by gastric intubation produced 24-hour serum concentrations above the MICs for the Shigella isolates from this outbreak.

Animals↗
PubMed1991

Suitability of the broth-disk elution test for evaluating susceptibility of obligate anaerobes to trimethoprim-sulfonamides.

Species of anaerobic bacteria isolated from clinical veterinary specimens were tested for susceptibility to trimethoprim-sulfonamides by the broth-disk elution technique. Three different media were used for each organism: prereduced anaerobically sterilized (PRAS) brain-heart infusion broth (BHI), thioglycollate broth, and a semidefined PRAS medium. Susceptibility results from these media were compared with those determined by interpreting the minimal inhibitory concentration obtained using an agar dilution technique. Results from broth-disk testing in semidefined medium agreed in 68.7% of the cases, in 53.7% for thioglycollate broth, and in 36.9% for BHI. The greatest deviation between techniques occurred with isolates belonging to the genus Bacteroides, followed by those of the genus Clostridium and those of the genus Fusobacterium. This deviation was directly proportional to increasing concentrations of thymidine in the BHI and thioglycollate broths but not with the semidefined medium. We conclude that the broth-disk elution method for measuring susceptibility of obligate anaerobes to trimethoprim-sulfonamides is unsuitable.

Animals↗
PubMed1991

Distribution of indole-producing urease-negative pasteurellas in animals.

Three hundred fifty-six animal isolates of indole-positive urease-negative cultures of Pasteurella, which would formerly have been classified as P. multocida, were examined with respect to their relationship to the recently described P. multocida subspecies (ssp.) multocida, septica, and gallicida and P. canis, P. stomatis/Taxon 16, and Pasteurella sp. B. Two hundred sixty-three (73.9%) of the cultures could be identified with one of these taxa, and 93 isolates (26.1%), representing 17 different biotypes, were unassignable. Pasteurella multocida ssp. multocida was the predominant taxon throughout and in most of the 25 animal species from which isolations were made. In dogs, P. canis was the most frequent. Different degrees of host predilection were observed also in P. multocida ssp. septica for cats, P. canis for sheep, and 2 of the unassignable biotypes for cattle and dogs, respectively. Overall, the respiratory tract was the most frequent source of isolates, but a propensity of P. multocida ssp. septica for localization in the central nervous system of cats was noted.

Animals↗
PubMed1991

Molecular epidemiology of Pasteurella multocida in turkeys.

Pasteurella multocida isolated from turkeys during an outbreak of fowl cholera was characterized by serotype and heterogeneity of genes encoding rRNA (ribotype) to investigate the epidemiology of the organism. Isolates were collected between October 1985 and July 1986. The M9 or Clemson University fowl cholera vaccine-like strain was detected in 17% of the flocks with fowl cholera. One particular strain, isolated only from breeder flocks, was recovered from 7 of the 10 breeder flocks examined in this study. Intracompany transmission appeared to be common, implying a failure in biosecurity. Circumstantial evidence indicated that in the field; the incubation period of P multocida in a turkey flock may be between 2 to 7 weeks. Wildlife did not appear to be an important reservoir of P multocida for turkeys during this study period. Ribotyping results tended to discount several of the possible interflock transmissions, as suggested by examination of serotyping results alone; however, serotyping in combination with ribotyping proved helpful in understanding the epidemiology of P multocida in turkeys.

Animals↗
PubMed1991

Identity of Bacteroides isolates and previously named Bacteroides spp in clinical specimens of animal origin.

During the years 1984 through 1987 2,574 isolates of obligately anaerobic bacteria were isolated from samples submitted for analysis. The most common anaerobic isolates were members of the genus Bacteroides, representing 44.6% of the isolates. Of these, the most commonly isolated identifiable microorganisms were bile-resistant and nonpigmented, belonging to the B fragilis group of Bacteroides. Importantly, obvious predilections for any one species or group of Bacteroides were not apparent for animal or site (condition), except that the proportion of isolates belonging to the nonpigmented, bile-resistant group obtained from the respiratory tract was significantly (P less than 0.005) higher than that not belonging to this group. On the other hand, the proportion of isolates of the non-pigmented, bile-resistant group obtained from abscesses was significantly lower than that not belonging to this group.

Animals↗