Pathophysiologic studies in human rabies.

Six patients with proved rabies were studied with a combination of clinical, physiologic and pathologic technics. Three were given a type of intensive care but died with evidence of respiratory failure. Although circulatory failure did not develop in any of the six patients, three had supraventricular arrhythmias: interstitial myocarditis was found in one of these and rabies virus was isolated from the myocardium of another. Inspiratory muscle spasm was the dominant clinical feature in all cases. This occurred as part of the hydrophobic response and followed stimulation of the upper respiratory tract and skin. Hydrophobia may represent an exaggerated respiratory tract irritant reflex with associated arousal. Later in the course of the disease, various patterns of periodic and ataxic breathing were observed. Widespread brain stem encephalitis was discovered at autopsy, with particular involvement of the neighborhood of the nucleus ambiguous in two of three patients examined. In one patient cerebral metabolism was grossly abnormal, with greatly reduced cerebral oxygen consumption suggesting irreversible brain damage. Respiratory and circulatory disturbances may well be immediate causes of death in patients with rabies, but the present studies reemphasize the severity of the encephalitis which remains the ultimate barrier to survival. In the developing countries in which rabies is still a major problem and in which the cost precludes intensive care, the clinical management of rabies can aim only to reduce suffering by heavy sedation.

Rhodococcus equi in fecal and environmental samples from Kansas horse farms.

Horse farms in Kansas were surveyed for the incidence of Rhodococcus equi. Fecal specimens and soil or cobweb samples were collected from each farm and cultured on selective media. One control farm (with no history of R. equi infection), one farm which had an outbreak 3 and 4 years previously and 2 farms which had R. equi-infected foals that season were surveyed. In addition, fecal samples from 21 horses hospitalized in the Kansas State University Veterinary Hospital were cultured. There was no significant difference in the incidence of R. equi in fecal samples from the 2 farms with recent disease problems. The farm with a history of disease had a significantly higher percentage of positive fecal cultures than the 2 farms with a more recent history of disease. Neither ration composition nor sex of the horses appeared to affect the fecal culture results. Fecal samples from 2 birds on 1 farm were positive for R. equi.

Isolation and characterization of nutritionally variant streptococci from animal sources.

Ten nutritionally variant streptococci were recovered from clinical specimens submitted to the Kansas State University Veterinary Clinical Bacteriology laboratory over a 4-year period. Isolates were recognized visually on primary blood agar plates by their satellite growth around a previously overlaid Staphylococcus aureus culture. All isolates grew within 24 hours in Todd-Hewitt and heart infusion broths supplemented with 5% bovine fetal serum and 5% S aureus filtrate. They also grew anaerobically in supplemented broths within 48 hours. However, isolates did not grow aerobically or anaerobically in the absence of supplements up to a 7-day postinoculation period. As determined by the standard Kirby-Bauer technique, the isolates were highly susceptible to antimicrobial agents commonly recommended in veterinary medicine. The isolates did not react with the corresponding Lancefield group-specific antisera, as tested by the capillary precipitin test.

Clinical and pathologic studies of experimentally induced Pasteurella haemolytica pneumonia in calves.

Pasteurella haemolytica pneumonia of the right caudal lung lobe was experimentally induced in 2-week-old Holstein calves (n = 11) by endobronchial inoculation of 7.9 x 10(10) colony-forming units of 6-hour log-phase bacteria. Calves were studied for 72 hours after inoculation. The challenge procedure consistently induced a lesion in the right caudal lung lobe, which was consistent radiographically with results of pathologic examination and a similar volume of bronchography contrast medium. Clinically, the calves developed a significant increase in rectal temperature within 24 hours after inoculation. Seventy-two hours after inoculation, the total WBC counts, absolute band neutrophil counts, monocyte counts, and blood fibrinogen concentrations were significantly higher than normal and albumin concentration was significantly decreased. Necropsy revealed a circular to oblong lesion that was congested, edematous, and firm and occupied 20 to 40% of the right caudal lung lobe. Histologic examination revealed a severe acute inflammatory reaction characterized by cellular exudate and proteinaceous fluid in the alveoli, interlobular septa, and pleura.

Passive protection of mice with antiserum to neuraminidase from Pasteurella multocida serotype A:3.

Antiserum to a partially purified neuraminidase from Pasteurella multocida, type A:3, was adsorbed with protease-digested P. multocida type 3 lipopolysaccharide (LPS) to remove LPS immunoreactivity. The LPS-adsorbed antineuraminidase caused a 77% reduction in the neuraminidase activity of homologous P. multocida in an in vitro enzyme neutralization test. All 14 mice passively immunized with the adsorbed antineuraminidase were protected against challenge infection with homologous P. multocida in a mouse protection test. Ten out of 14 mice in one group that received antisera containing antibodies to both neuraminidase and LPS were protected. In contrast, only 1 out of 14 mice that were immunized with pre-immune serum survived the challenge. These results suggest that antiserum to P. multocida neuraminidase was, at least partly, responsible for the protection observed in this study. Neuraminidase may be one of the immunogenic protective proteins present in aqueous extracts of Pasteurella multocida.

Identification of type D Pasteurella multocida by counterimmunoelectrophoresis.

A counterimmunoelectrophoresis (CIE) test was applied to serotype 35 isolates of type D Pasteurella multocida recovered from 32 cases of atrophic rhinitis (in swine) and 3 cases of snuffles (in rabbits). The CIE test was compared with the indirect hemagglutination (IHA) and acriflavine (AF) tests. Results of the CIE test correlated 100% with those of the IHA test whereas results of the AF test correlated 91.43% with those of the IHA test. The CIE test was rapid and simpler to perform compared with the IHA test and more sensitive than the AF test. Cross-reactions were not encountered with capsular antigens of P. multocida types A, B, and E in the CIE test. The CIE test was not found to be suitable for typing type A P. multocida strains.

Comparison of indirect hemagglutination and rapid plate agglutination tests with counterimmunoelectrophoresis for typing Pasteurella haemolytica.

A rapid, simple, and accurate counterimmunoelectrophoresis (CIE) technique was developed and compared with the indirect hemagglutination and rapid plate agglutination techniques for serotyping cultures of Pasteurella haemolytica. The CIE test had 100% correlation with the conventional indirect hemagglutination test and, after serum absorption, correctly identified cultures representing the 12 established serotypes and 49 field isolates of P. haemolytica with reasonable rapidity. Cross-reactions were observed in the CIE and rapid plate agglutination tests but not in the indirect hemagglutination test with antisera prepared from the 12 established serotypes. These cross-reactions were eliminated from the CIE test but not from the rapid plate agglutination test by absorption of antisera with cells which possessed the cross-reacting antigens. Avian isolates of P. haemolytica did not type with antisera to the 12 established serotypes by any of the methods. Both homologous and heterologous reactions were observed with these strains in the rapid plate agglutination and CIE tests with antisera prepared from six selected cultures. These results support the previous finding that the taxonomic relationship of these avian strains to P. haemolytica is questionable.

Aerobic bacterial flora of oral and nasal fluids of canines with reference to bacteria associated with bites.

Oral and nasal fluids of 50 dogs were examined to determine the prevalence of aerobic bacteria frequently associated with animal bite wounds. The most frequently isolated microorganisms included: IIj, EF-4, Pasteurella multocida, Staphylococcus aureus, Staphylococcus epidermidis, group D streptococci, Corynebacterium sp., Enterobacteria, Neisseria sp., Moraxella sp., and Bacillus sp. Other species and genera were infrequently recovered and may represent transient flora. The high incidence of IIj, EF-4, P. multocida, and S. aureus, all known human pathogens, suggests that they should be considered as probably contaminants in bite wounds.

Demonstration during life of rabies antigen in humans.

In three cases of human rabies, in which the diagnosis was proved postmortem, rabies antigen was detected by direct immunofluorescence of frozen sections of facial skin. The antigen was thought to be in nerve fibers in association with hair follicles. Development of this technique might enable the establishment of a method for the diagnosis of human rabies during life.