Naturally acquired infections of Klebsiella pneumoniae in Wistar rats.

Klebsiella pneumoniae was isolated from lesions in 2 dead and 82 ill animals in a breeding colony of 2300 Wistar rats. The clinical signs were unilaterial and bilateral fluctuating masses in the cervical and inguinal areas, and focal cutaneous ulcers in the ventral neck. Cervical and inguinal lymphadenitis with abscess formation were found on microscopic examination. Lesions also occurred in visceral organs. Although characteristic of the natural infection in most species, no respiratory lesions were seen in this epizootic episode. A capsular serotype 5 K. pneumoniae which did not utilize malonate was the only bacterial strain cultured from the lesions, but other K. pneumoniae strains that utilized malonate and were untypable by capsular serology were cultured from throats and faeces. 30% (6/20) of asymptomatic animals tested had both types of K. pneumoniae in their faeces.

Enzyme-linked immunosorbent assay for evaluation of antibody to canine distemper virus.

An enzyme-linked immunosorbent assay (ELISA) for canine immunoglobulin (Ig) G antibodies to canine distemper virus (CDV) was developed and its test results were compared with those of the serum-neutralization (SN) test. The sera of 273 random-source adult dogs were examined. The two tests had a high degree of correlation. Very few discrepancies occurred and most of these were at the lower limits of each test. When the sera were tested at 1:100 dilution, there was a 98% agreement between the ELISA and SN test. Titrated SN and IgG ELISA tests also were performed on sera from 77 dogs whose lifetime medical histories were known. The results showed excellent agreement between the tests. Only five of the 77 sera showed any discrepancies and these were at detection-threshold levels. To follow antibody development in two dogs experimentally infected with CDV, it was necessary to use an ELISA which detected both canine IgM and IgG. The ELISA detected CDV-specific IgM a week before the SN test results became positive. The IgM titers rose for 3 weeks and descended to lower levels about the 4th and the 5th weeks. The SN titers closely followed the IgM titers. The ELISA detected IgG antibody about the 5th and the 6th weeks of infection. Results of both the SN test and the IgG ELISA remained elevated through the 70th day of testing.

An enzyme-linked immunosorbent assay for the detection of canine antibodies to canine adenoviruses.

An enzyme-linked immunosorbent assay was used to detect canine immunoglobulin G antibodies specific for infectious canine hepatitis virus and the serologically related canine adenovirus Type 2. The sequential development of homologous and heterologous antibodies was measured by the enzyme-linked immunosorbent assay and serum neutralization tests in two groups of dogs which were experimentally infected with either infectious canine hepatitis virus or canine adenovirus Type 2. Both tests were comparable in their abilities to detect the development of homologous and heterologous antibodies. Homologous antibodies were detected earlier and to a higher titer in both tests. There was a 98% agreement between the serum neutralization test and the enzyme-linked immunosorbent assay when sera from 224 random-source dogs were examined for infectious canine hepatitis virus antibodies. The enzyme-linked immunosorbent assay was found to be a highly efficient and rapid test to determine the immune status of dogs to infectious canine hepatitis virus and canine adenovirus Type 2.

Detection and definition of canine intestinal carbohydrases, using a standardized method.

Intestinal mucosa and pancreas from purebred Beagle dogs were assayed for carbohydrase activity, using several methods of tissue treatment. The enzymes found and studied were alpha-amylase, sucrase, lactase, amyloglucosidase, cellobiase, maltase, and isomaltase. Experiments using polyacrylamide gel columns and heat inactivation showed the presence of an isozyme of maltase which degrades isomaltose. This activity had not been previously demonstrated in dogs. An optimal standard procedure is presented for the preparation and assay of canine digestive enzymes. A statistical analysis of variance of the results showed that the variance was primarily associated with differences among dogs and not by variance within the procedure. When the different extraction procedures were used, results indicated that the level of enzymes detected differed with the method of treatment.

Variable ammonia production among smooth and rough strains of Pseudomonas pseudomallei: resemblance to bacteriocin production.

The colonial morphology of some strains of Pseudomonas pseudomallei was correlated with certain biochemical and physiological traits. After 3 days of growth on Wahba or heart infusion agars, smooth-colony strains generated toxic amounts of ammonia. Under the same conditions, the rough strains simultaneously produced oxalic acid which decreased the inhibitory concentration of ammonia. The ammonia-ammonium concentrations in smooth cultures exhibited certain bacteriocin-like characteristics. An unusually stable, smooth strain (strain 165) was chosen to compare and emphasize any differences with typical, rough strain 7815. Three-day-old smooth cultures grown on Wahba agar containing 3% (w/v) glycerol demonstrated ammonia toxicity. The substitution of glucose for glycerol completely obviated this toxicity. In highly aerated Wahba broth containing glucose, the amount of ammonia found in strain 165 smooth cultures and the amount of oxalic acid found in strain 7815 rough cultures were greatly reduced. In Difco nitrate broth smooth strain 165 did not form gas, and it reduced nitrate to nitrite only. Strain 7815 produced a gas and reduced both nitrate and nitrite.

Nucleic acid similarities among Pseudomonas pseudomallei, Pseudomonas multivorans, and Actinobacillus mallei.

Annealing experiments on membrane filters were carried out with deoxyribonucleic acids (DNA) from selected strains of the nomen-species of Pseudomonas, Actinobacillus, Chromobacterium, and Micrococcus, with the use of DNA of Pseudomonas pseudomallei and Actinobacillus mallei as reference materials. Under the usual conditions employed in these experiments, the results were not quantitatively reproducible. Incorporation of dimethylsulfoxide (DMSO) into the incubation medium greatly increased differences in comparative binding. DNA binding in agar matrices was examined in the presence and absence of DMSO at various incubation temperatures. It was found that the greatest specificity, stability, and total binding for DNA containing high amounts of guanine and cytosine occurred in the presence of DMSO. Under the most stringent annealing conditions permitted in agar, DNA species from P. pseudomallei and A. mallei in the presence of DMSO demonstrated interspecific relative bindings of 76 to 86% when compared to the homologous reactions. The thermal elution midpoints (E(m)) of these duplexed interspecific DNA species were quite close to the homologous E(m) values. The relative bindings of P. multivorans DNA types to either reference DNA ranged between 6 to 27%, and the E(m) values were 4 to 7 C less than those for the homologous reactions.

Deoxyribonucleic acid base composition and homology studies of Leptospira.

Four distinct genetic groups of leptospiras were demonstrated among selected pathogenic and "biflexa" serological types. Pathogenic leptospiras could be divided into two groups on the basis of per cent guanine + cytosine (GC) in their deoxyribonucleic acid (DNA). One group had 36 +/- 1%, the other 39 +/- 1%. The biflexa strains had DNA of 39 +/- 1% GC, but were further separated into two groups on the basis of DNA-annealing tests. Strains within groups had a high degree of specific duplex formation (75% binding or more with reference to the homologous DNA). There was little or no genetic relatedness between strains of the four groups (less than 10% DNA homology). The thermal elution midpoint of heterologous DNA duplexes was always lower than the homologous reaction. The serological relationships among strains were not meaningful in terms of relatedness determined by specific duplex formation.