Comparison of ticarcillin and piperacillin in Kenney's semen extender.

Ticarcillin and piperacillin were compared to determine their effect on sperm motility and bacterial growth of equine semen samples diluted in Kenney's glucose skim milk semen extender. Each ejaculate (n=11) was divided into three portions and glucose skim milk semen extender solution was added. The control semen extender solution contained extended semen and no antibiotic, whereas ticarcillin and piperacillin solutions contained extended semen plus 1.0mg/mL of ticarcillin or piperacillin, respectively. An aliquot was removed (1h after collection) to evaluate sperm motility and microbial concentration. All three solutions were stored at 4 degrees C and aliquots were obtained at 24 and 48 h to determine sperm motility and microbial concentration. Mean percentages of motile and progressively motile sperm did not differ significantly among control and antibiotic-containing solutions after storage. Control-extended semen samples from ejaculates of stallions (n=11) were contaminated with aerobic gram-positive and gram-negative bacteria. In solutions that contained either antibiotic, growth of these microbes was inhibited after 1, 24, and 48 h at 4 degrees C. Semen samples from stallions (n=5) were extended with Kenney's glucose skim milk extender containing no antibiotic, ticarcillin or piperacillin and then inoculated with approximately 5 x 10(2)CFU/mL Klebsiella pneumoniae or Pseudomonas aeruginosa; there was no significant difference between antibiotics in the inhibition of microbial growth. In conclusion, piperacillin was an appropriate alternative to ticarcillin in extenders for equine semen.

Regulation of GMP reductase in Salmonella typhimurium.

The levels of guanosine 5'-phosphate reductase (EC 1.6.6.8) in Salmonella typhimurium appear to be modulated by changes in the ratio of the adenine and guanine nucleotide pools. Alterations of this ratio may be induced by high levels of guanosine in the culture medium or by genetic lesions in one of several purine interconversion enzymes, such as pur A or pur B mutants. The induction of the reductase requires transcription and translation processes and, in contrast to earlier observation with Escherichia coli, is not dependent on cyclic adenosine 3',5'-phosphate or the cyclic adenosine 3',5'-phosphate receptor protein.

Growth of Salmonella enteritidis in artificially contaminated eggs: the effects of inoculum size and suspending media.

Growth profiles of two isolates of Salmonella enteritidis phage type (PT) 4 inoculated into either the albumen of whole shell eggs or into separated albumen were found to be markedly affected by the size of the inoculum and the composition of the medium used to suspend the cells prior to inoculation. Using our model with an inoculum of two cells, multiplication of the Salmonella was not seen in 93% of eggs held at 20 degrees C for 8 days. In approximately 7% of eggs, however, growth occurred during the 8 days of storage. If the inoculum equaled or exceeded 25 cells per egg when eggs were subsequently stored at 20 degrees C, or 250 cells per egg when eggs were stored at 30 degrees C, high levels of growth of Salmonella in the egg occurred significantly more frequently than when the inoculum was two cells. High levels of growth were also seen more frequently if the inoculum was suspended in buffered peptone water or maximal recovery diluent rather than in phosphate buffered saline. Growth of Salmonella in separated albumen occurred very infrequently (1.1% of samples) at low inoculum levels and did not become significant until the inoculum was 250 cells or greater. Growth in the albumen was unaffected by the composition of the suspending medium. Provided that the inoculum was approximately 2 cells per egg and the bacteria were suspended in PBS, observed growth profiles of S. enteritidis inoculated into the albumen of whole eggs resembled those in naturally contaminated eggs.

Comparison of environmental monitoring protocols for the detection of Salmonella in poultry houses.

Environmental monitoring has been used as a screening method to detect Salmonella enteritidis infection in laying hens. Several transport protocols (buffered peptone water, skim milk, asparagine, double distilled water, and no media), to be used for the detection of Salmonella in environmental samples from poultry houses, were compared for their ability to preserve the integrity of specimens. The isolation rates of Salmonella using the various transport protocols, including double-strength skim milk and no media (dry), were similar. Use of dry swabs is more convenient than a media transport system and should be adopted as an alternative method.

Evaluation of disinfectants against Salmonella enteritidis.

Five classes of disinfectants (phenol, quaternary ammonium, chlorine, glutaraldehyde, and a combination of quaternary ammonium and formaldehyde) were diluted in "field" water (well, stream, or pond water) and compared with dilutions of the disinfectants in laboratory-grade water for their efficacy against the AOAC (Association of Official Agricultural Chemists) test organism Salmonella cholerasuis (ATCC 10708), S. enteritidis isolated from the spleen of an infected laying hen, and an egg-invasive S. enteritidis isolate. In all cases when S. cholerasuis was used, there was a significant association between the use of well, pond, and stream water and the growth of the bacterium. If we exclude glutaraldehyde, there was also a significant association between the use of "field" water and the growth of both isolates of S. enteritidis. There was no significant association when glutaraldehyde was used. There was a significant association between the use of lab water and the growth of S. enteritidis. The results suggested that the inability to remove S. enteritidis from layer houses may in part be associated with the source of water. Variables in pH, hardness, conductivity, nitrate content, or bacterial contamination of the water did not appear to affect the ability of the disinfectant to kill S. enteritidis. If "field" water is used for disinfection against S. enteritidis, the use of quaternary ammonium, the combination (quaternary ammonium/formaldehyde), or phenol should be considered.

Differences among restriction endonuclease DNA fingerprints of Pennsylvania field isolates, vaccine strains, and challenge strains of infectious laryngotracheitis virus.

Restriction endonuclease fingerprints of infectious laryngotracheitis virus (ILTV) DNA from 13 Pennsylvania field isolates, embryo-propagated and tissue-culture-propagated vaccine strains, and three reference strains were compared. These comparisons were made to evaluate the possible contribution of mutation of ILTV vaccine strains to recent outbreaks of infectious laryngotracheitis (ILT) in Pennsylvania. Six different restriction enzymes were used to generate the fingerprints. Differences in DNA banding patterns were revealed between the currently used ILTV vaccine strains and six of the 13 field isolates. Even greater DNA banding pattern differences were found between the older ILTV reference strains and the vaccine strains. The ILTV DNA fingerprints generated in the present study suggest that at least five different strains of ILTV have contributed to the outbreaks of ILT that have occurred since 1987 in Pennsylvania.

Evaluation of disinfectants with the addition of antifreezing compounds against nonpathogenic H7N2 avian influenza virus.

In the winter of 1997 and 1998, in the midst of the H7N2 avian influenza outbreak in Pennsylvania, producers added antifreeze or windshield washer fluid to disinfectant solutions in wash stations to prevent freezing. The purpose of this study was to determine if the addition of these products to the disinfectant solutions would have deleterious effects. Four disinfectants (two phenols, one quarternary ammonium, and one combination product: quarternary ammonium and formaldehyde) and one sodium hypochlorite detergent product currently used in the poultry industry were studied. Each product was diluted according to the manufacturer's recommendation in sterile distilled water and compared with dilutions of the disinfectants with the addition of antifreeze products (ethylene glycol or propylene glycol) or windshield washer fluid for their effectiveness in killing nonpathogenic H7N2 avian influenza virus. All products diluted according to the manufacturer's recommendation killed the nonpathogenic H7N2 avian influenza virus in this test system. The phenol products and the quaternary ammonium product were still efficacious with the addition of the antifreeze containing ethylene glycol. Both the combination product and the sodium hypochlorite detergent had decreased efficacy when the ethylene glycol product was added. When the propylene glycol product was added, the efficacy of all disinfectants remained unaffected, whereas the efficacy of the sodium hypochlorite detergent decreased. With the addition of the windshield washer fluid (methyl alcohol), all products remained efficacious except for the combination product.

Field observations with Salmonella enteritidis bacterins.

A study involving 11 commercial layer flocks was conducted to determine the efficacy of Salmonella enteritidis bacterins (autogenous or federally licensed). The criterion for evaluation of vaccine efficacy was the presence or absence of S. enteritidis in the environment, the organs of the bird (including ovary and oviduct), and eggs. Environmental, rodent, and organ specimens from dead birds as well as eggs were cultured throughout the life of the flock. All layers were obtained from pullet sources that were negative for S. enteritidis, as determined by organ and environmental cultures. Despite the use of S. enteritidis vaccination, 63.6% of the houses had S. enteritidis-positive environmental cultures and 100% of the flocks had S. enteritidis organ-culture-positive birds. The range of positive cultures for S. enteritidis in the environment in vaccinated flocks was between 0 and 45.5%. Birds in vaccinated flocks were organ-culture positive for S. enteritidis between 10% and 40% of the time. The unvaccinated portion of flocks in the same house and the unvaccinated flock in a complex had similar results compared with the vaccinated portion of the flocks.

Monoclonal antibody-based detection system for Salmonella enteritidis.

Two monoclonal antibodies that react with Salmonella enteritidis in chicken tissue, eggs, and environmental samples were used to develop a rapid enzyme-linked immunosorbent assay (ELISA) screen and agglutination assay for the specific detection of S. enteritidis. S. enteritidis was detected in 100% of egg samples and 99.8% of various field and research samples by both ELISA and traditional microbiological isolation and identification techniques. Results of titer experiments indicate that as few as 10(4) organisms can be detected by ELISA.

Invasion of chicken reproductive tissues and forming eggs is not unique to Salmonella enteritidis.

Experiments were conducted in which Salmonella enteritidis Phage Type 8, Phage Type 2, and RDNC (reaction does not conform) or three isolates of Salmonella typhimurium of diverse origin were fed to adult laying hens to determine if S. enteritidis has a selective advantage over S. typhimurium, which is now rarely isolated from chicken eggs, in its capacity to invade reproductive tissues. The results revealed that S. enteritidis and S. typhimurium may be equal in their potential to colonize the tissues of the reproductive tract and eggs that are forming in the oviduct prior to oviposition. S. enteritidis, but not S. typhimurium, was isolated from egg contents after oviposition. The degree to which intestinal, hepatic, splenic, or reproductive tissues were colonized by either serotype was not seen to affect the rate of colonization of eggs forming in the oviduct or the contamination of eggs after oviposition. Virulence factors related to the difference in the association of S. enteritidis and S. typhimurium with egg-borne salmonellosis remain to be defined.

Studies on oral transmission of Potomac horse fever.

Eight normal ponies placed in direct contact with ponies experimentally infected with Ehrlichia risticii for 30 to 90 days did not develop signs of Potomac horse fever. They also did not seroconvert, and they remained susceptible to IV infection. One of 8 ponies that were force fed fresh feces from infected ponies while in direct contact with ponies experimentally infected with E. risticii developed Potomac horse fever and seroconverted. The other 7 remained asymptomatic, did not seroconvert, and were susceptible to IV infection. Six of 9 ponies inoculated with E. risticii via nasogastric intubation and oral drench developed Potomac horse fever and seroconverted. The other 3 remained asymptomatic and did not seroconvert. One of these latter ponies and 2 normal ponies that were inoculated via oral drench only developed Potomac horse fever and seroconverted. The high fever, maximum clinical score for decreased feed intake, depressed mental attitude, decreased borborygmal sounds, severity of diarrhea, and the length of illness of the orally infected ponies was not significantly different from those of IV infected control ponies, although the signs occurred significantly later (P < .05).

Efficacies of trimethoprim-sulfadiazine and gentamicin sulfate in the treatment of fibrinous peritonitis in rats.

Trimethoprim-sulfadiazine and gentamicin sulfate decreased early mortality in an established model of fibrinous peritonitis in the rat. Both drugs failed to prevent abscess formation, indicating that there was poor penetration of fibrin; however, they significantly decreased (P less than 0.01) bacterial numbers in residual abscesses. The colony count per abscess in the gentamicin sulfate-treated group was significantly lower (P less than 0.01) than that in the trimethoprim-sulfadiazine-treated group.

Effect of treatment with erythromycin and rifampin during the acute stages of experimentally induced equine ehrlichial colitis in ponies.

Sixteen healthy ponies were inoculated IV with Ehrlichia risticii-infected P388D1 mouse monocytes. Of the 16 ponies, 15 developed clinical signs of equine ehrlichial colitis. Twenty-four hours after onset of fever (rectal temperature > 38.8 C), 7 ponies were treated with 25 mg of erythromycin stearate/kg of body weight and 10 mg of rifampin/kg, given orally every 12 hours for 5 days. The remaining 8 ill ponies served as nontreated controls. All ponies were observed for progression of clinical signs typical of equine ehrlichial colitis. Within 12 hours of initiation of treatment, 4 of the 7 treated ponies had rectal temperature < 38.4 C and, within 24 hours, 6 of the 7 ponies had rectal temperature < 38.3C. In contrast, all control ponies had rectal temperature > 39.2 C at 24 hours (P < 0.05). Of the 7 treated ponies, 4 no longer had signs of mental depression after the second day of treatment, and only 1 of the 7 ponies had mild signs of depression after the third day of treatment. In contrast, control ponies had high mental depression score during the observation period (P < 0.05). Feed intake improved in ponies of the treatment group, with feed intake of 4 of the 7 ponies returning to normal; the other 3 ponies were only mildly anorectic by the second day of treatment. Control ponies progressively decreased their feed intake during the observation period (P < 0.05). One control pony and 2 treated ponies developed diarrhea before the treatment/observation period began. Only 1 treated pony developed diarrhea after treatment began. Of the 8 control ponies, 7 developed diarrhea.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of treatment with oxytetracycline during the acute stages of experimentally induced equine ehrlichial colitis in ponies.

Eighteen ponies were inoculated IV with Ehrlichia risticii-infected P388D1 mouse monocyte cells. Twenty-four hours after onset of fever (rectal temperature > 38.8 C), 9 ponies were treated with oxytetracycline (6.6 mg/kg of body weight, IV, q 24 h) for 5 days. The remaining 9 ponies served as infected nontreated controls. Mean scores of the following variables were not significantly different between groups on the day treatment was begun: rectal temperature, diarrhea, borborygmal sounds, feed intake, mental attitude, and evidence of a hyperresonant area in the abdomen. All ponies were observed for progression of clinical signs typical of ehrlichial colitis. Within 12 hours of initiation of treatment, only 1 treated pony had a rectal temperature > 38.8 C and most rectal temperatures were < 38.3 C. In contrast, only 2 control ponies had rectal temperatures < 38.8 C (mean rectal temperature values were significantly, P = 0.01, different between groups). In the treatment group, 4 ponies had no signs of depression after the first day of treatment, and only 1 had signs of depression after the second day of treatment (mean scores between groups were significantly different, P = 0.01). Feed intake remained normal in 4 treated ponies and improved in 4 of the remaining 5 after treatment began. Most of the control ponies had a progressive decrease in their feed intake during the observation period (mean scores between groups were significantly, P = 0.01, different). Three ponies in the control group and 2 ponies in the treatment group developed diarrhea before the treatment observation period began.(ABSTRACT TRUNCATED AT 250 WORDS)

Oxidative metabolism of the bovine alveolar macrophage.

Oxidative respiratory burst activity was examined in lavage-procured bovine pulmonary alveolar macrophages. Nonstimulated alveolar macrophages released a minimal quantity of superoxide anion and had small amounts of glucose flux through the pathways of energy metabolism. Nonstimulated cells metabolized substantial amounts of glucose through the hexose monophosphate shunt. Stimulation with opsonized zymosan particles induced a tenfold increase in the release of superoxide anion and a twofold increase in the flux of glucose through the hexose monophosphate shunt and the pathways of energy metabolism. Preliminary observations also indicated that the magnitude of the burst varied between sets of bronchoalveolar cells obtained from the same calf over time.

Resistance to development of equine ehrlichial colitis in experimentally inoculated horses and ponies.

Fourteen ponies and 3 horses were inoculated with Ehrlichia risticii 2 to 20 months after a similar initial inoculation. Although all 17 had clinical signs of equine ehrlichial colitis after the first inoculation, 16 of 17 remained clinically normal following the second inoculation. The remaining pony had a transient fever and developed signs of depression. Before the initial inoculation, none of the animals had a detectable antibody titer to E risticii. All animals developed titers after the initial infection; however, a significant change of titer did not develop after reinoculation in most animals.

Production of superoxide anion by bovine pulmonary macrophages challenged with soluble and particulate stimuli.

The effects of opsonized zymosan, phorbal myristate acetate, and live Pasteurella haemolytica on superoxide anion production by bovine pulmonary macrophages were determined. The anion responses were dose-dependent for all stimuli, except for unopsonized P haemolytica. The effect of viable P haemolytica on macrophage viability was related to bacterial dosage and the presence of opsonizing antibody. Superoxide responses varied directly with the dose of opsonized live P haemolytica, but indirectly with macrophage viability.

Resistance to gentamicin and amikacin of gram-negative organisms isolated from horses.

Resistance of gram-negative bacteria to gentamicin has become an increasingly common problem among clinical isolates from human beings. Susceptibility of isolates from horses to gentamicin and amikacin was evaluated for the period from July, 1983 to June, 1985. All isolates of Escherichia coli, and species of Enterobacter, Klebsiella, Proteus, and Pseudomonas examined were susceptible to amikacin, except 2 of the 46 Pseudomonas isolates. In contrast, 13 to 50% of isolates were resistant to gentamicin. Escherichia coli, and Klebsiella, Proteus, and Enterobacter species isolates were highly significantly more susceptible to amikacin (P less than 0.01) than to gentamicin. Pseudomonas spp (P = 0.13) were not significantly different in susceptibility to the 2 drugs. There was significant variation among genera in their susceptibility to gentamicin (P = 0.002), primarily because of the frequency of resistance in isolates of Klebsiella spp and Proteus spp, compared with the other 3 organisms (E coli, Enterobacter spp, and Pseudomonas spp). There was no significant difference of susceptibility to amikacin among the genera studied (P = 0.06).

Comparison of uterine protein content and distribution of bacteria in the reproductive tract of mares after intrauterine inoculation of Haemophilus equigenitalis or Pseudomonas aeruginosa.

Two groups of 3 mares were inoculated with Haemophilus equigenitalis or Pseudomonas aeruginosa on the 1st day of estrus. Uterine flushing samples were recovered on day 3 of estrus and day 8 after ovulation for each cycle. Mares were killed 22, 25, and 30 days after inoculation with P aeruginosa and 45, 46, and 49 days after inoculation with H equigenitalis. Pseudomonas aeruginosa was recovered from the uterus of 2 mares 48 hours after inoculation. Although the initial flushing sample of 1 of these 2 mares had an increased total protein concentration, there appeared to be little difference between protein concentrations of other uterine flushing samples. Haemophilus equigenitalis was recovered from the uterus of each of the 3 mares at postmortem. One mare had a slight, purulent discharge from the vulva. Total protein values were not increased in flushing samples from this mare after inoculation with H equigenitalis. Total protein values decreased in the last flushing sample of each of the 2 remaining mares. Swabbing the uterus was more effective than was homogenizing the uterine mucosa in isolating H equigenitalis.

Comparison of rectal mucosal cultures and fecal cultures in detecting Salmonella infection in horses and cattle.

Bacteriologic cultures of 65 rectal mucosal samples and 335 fecal samples from 53 horses and 5 cattle shedding Salmonella were performed. Salmonella spp were isolated from 34 (52%) rectal mucosal samples, 21 (32%) concurrent fecal samples, and 150 (45%) total fecal samples. The use of rectal mucosal samples when compared with concurrently obtained fecal samples significantly (P less than 0.025) improved the ability to isolate Salmonella spp. Concurrent bacteriologic culture of rectal mucosal samples and fecal samples resulted in 39 (60%) isolations. Compared with a series of fecal samples, Salmonella was isolated significantly more often when rectal mucosa and feces were cultured concurrently. Salmonella was isolated from rectal mucosal samples when it was not isolated from feces.