Vaccination studies against experimental bovine Pasteurella pneumonia.

Vaccination-challenge experiments were conducted in colostrum-deprived calves to evaluate the efficacy of Pasteurella bacterins and vaccines against experimental pneumonic pasteurellosis. Calves were vaccinated with formalin-killed bacterins and live vaccines, then challenge exposed intratracheally with P. haemolytica or P. multocida. Infectious bovine rhinotracheitis virus was inoculated intranasally three to four days prior to P. haemolytica challenge-exposure. All calves were examined for macroscopic and microscopic lesions after being found dead or following euthanasia four to seven days after challenge exposure with the bacterial pathogen. Clinical, hematological, and pathological responses to challenge exposure in aluminum hydroxide absorbed P. haemolytica and P. multocida bacterin-treated calves were consistent with the pneumonic lesions of pulmonary pasteurellosis in the control calves. An oil-adjuvanted P. haemolytica bacterin limited clinical and pathological responses in the affected calves whereas a P. multocida oil-adjuvanted bacterin did not. Both clinical and pathological responses to challenge exposure in calves vaccinated with live Pasteurella vaccines were less severe than those of the control calves. Vaccine effectiveness appeared to be dose dependent.

The enumeration of Leptospira interrogans serovar pomona by a bioluminescence ATP assay.

A rapid method for enumerating viable Leptospira interrogans serovar pomona cells was investigated using a bacterial adenosine triphosphate (ATP) assay. The ATP was assayed by the luciferin-luciferase bioluminescence reaction. Samples of serovar pomona grown in liquid polysorbate 80-bovine albumin (P80-BA) medium for 1-3 days were analysed for ATP content, culture density (nephelometry), direct cell count and most probable number of viable cells (MPNVC) as determined by the dilution tube technique. A linear relationship was found between ATP content and the number of viable cells over the range of 4 X 10(8) to 8 X 10(9) leptospires/ml. Over this range the correlation coefficient for ATP content versus viable cells (0.96) was similar to the coefficient for culture density versus the number of viable cells. The coefficient for direct counts versus the number of viable cells was smaller. The bioluminescence assay of bacterial ATP is a promising method for enumerating viable leptospires in pure culture.

Safety testing of Pasteurella multocida vaccines and bacterins in turkeys.

When U.S. Department of Agriculture-licensed Pasteurella multocida vaccines and bacterins were administered to healthy turkeys under controlled laboratory conditions, they did not cause an increase in death loss.

Treatment of calf scours with colostrum.

The calf of a cow vaccinated with an E coli strain 1751 bacterin developed scours 14 hours after oral challenge with E coli strain B44. The calf became almost moribund but fully recovered in several days after repeated oral administration of the dam's colostrum.

Use of furosemide to obtain bovine urine samples for leptospiral isolation.

The use of the diuretic furosemide made it possible to obtain samples of urine from cattle for leptospiral isolations. The drug was injected IV at a dose level of 0.8 mg/kg for heifers and 0.5 mg/kg for calves. The average time to first voiding in heifers was 19 minutes. The average time from the first to the second voiding was 17 minutes. The average time to the first voiding in four calves was 12 minutes; the average time from the first to the second voiding was 10 minutes. A decrease in urinary osmolarity provoked by furosemide created a more favorable condition for the survival of leptospires. Leptospires were isolated in 24 (72.7%) of 33 weekly cultural attempts with the aid of furosemide in three experimentally infected adult cattle. Serovar hardjo was isolated in 16 (57.1%) of 28 weekly cultural attempts with aid of the diuretic in four experimentally infected calves. The recovery frequency was 28.5% from the first voiding and 50% from the second. Leptospires were not isolated from urine obtained from the calves by manual stimulation. Untoward side effects that might have been attributable to furosemide were not observed. Furosemide appears to be well suited to obtain urine samples from cattle for leptospiral isolation.

Experimental infection of calves with Leptospira interrogans serotype szwajizak.

This is a report on the experimental infection of cattle with Leptospira interrogans serotype szwajizak. The principal clinical features in three 4-week-old Holstein-Friesian heifers intravenously inoculated were fever, listlessness, anorexia, weakness, and diarrhea. Szwajizak was isolated from the blood for the first 5 to 8 days after inoculation. Leptospires were recovered from kidneys, but not from liver, spleen, brain, or urine. Two of the 3 calves produced homologous agglutinins, with maximum serum titers of 1:80 and 1:160. The sera of the 2 calves that developed szwajizak agglutinins showed cross reactivity with wolffi and hardjo antigens. There were not significant differences of plasma and urine constituents between the inoculated calves and the control calf. Endocardial hemorrhages and large soft black-red spleen were present in the 2 calves given the greatest numbers of leptospires. Histopathologically, kidney of all infected calves had multiple small foci of lymphoid cells, chiefly pasmacytes, which were present in periglomerular and interstitial areas.

Viability of Leptospira interrogans serotype grippotyphosa in swine urine and blood.

Normal swine urine, devoid of its microbial flora, diminished the viability and virulence of Leptospira interrogans serotype grippotyphosa. Bovine serum albumin diluent effectively offset the urine's deleterious effects. Membrane filtration (0.45 micrometer) rendered urine free of bacteria, but permitted passage of limited numbers of leptospires. Most of the commonly used anticoagulants did not alter viability of grippotyphosa in whole blood. However, EDTA significantly reduced the number of viable cells.

Growth, virulence, and immunogenicity of Leptospira interrogans serotype szwajizak.

Leptospira interrogans serotype szwajizak was characterized by (1) its growth in polysorbate 80-bovine albumin medium, (2) its virulence and course of infection in laboratory animals, and (3) its immunogenicity. Growth of this organism was continuous and vigorous at 29 C and 37 C in liquid medium for 10 serial subcultures. Some specific lots of agar were superior to other agars if tested for the ability to support the growth of small inoculums. Individual colonies resulted from growth of small inoculums on solid polysorbate medium. Virulence of the organisms did not appear to be altered by 10 serial subcultures in liquid medium incubated at 29 C. The estimated median lethal dose of szwajizak for hamsters by the intraperitoneal route was 2 cells. Virulence, infectivity, and pathogenicity of szwajizak were shown in the hamster and the guinea pig. Protection results indicate the heat-inactivated szwajizak bacterin was a substantially better immunizing agent than the chemically inactivated bacterin. Serotype hardjo bacterins provided hamsters some protection against death if challenge exposed with szwajizak, but afforded no protection against infection.

Effect of hydroxamic acids on growth and urease activity in Corynebacterium renale.

Studies were conducted on the effect of four different hydroxamic acids (HA), hydroxyurea, acetohydroxamic acid, p-flurobenzoylhydroxamic acid and sorbylhydroxamic acid, on the growth and urease activity of Corynebacterium renale. The addition of each of these HA, at concentrations ranging form 10(-3) to 10(-5) M, to medium containing urea as the sole nitrogen source resulted in a lengthened lag period of growth the extent of which depended upon the concentration of each HA tested as well as the structure of the compound; that is, the size and (or) complexity of the side chain attached to the common terminal group of the molecule. However, the maximal growth levels achieved following conclusion of the exponential phase were not affected by the HA. Investigations on the effect of these HA on the urease activity of intact cells as well as cell-free extracts revealed that in each case the enzymatic activity was inhibited by each of the HA tested. The extent of inhibition with the intact cells was aobut one-half of that observed with cell-free extracts. Direct incubation of cell-free extracts as well as intact cells with each of the HA tested was required for maximal inhibition.