Lechiguana (focal proliferative fibrogranulomatous panniculitis) in cattle.

Lechiguana is a disease of cattle characterized by large, hard, subcutaneous swellings that grow rapidly and result in death after 3-11 months in untreated animals. Cattle treated with antibiotics recover. The disease has been reported from five states in south and southeastern Brazil. Histologically, the lesion consists of focal proliferation of fibrous tissue infiltrated by plasma cells, eosinophils, lymphocytes and sometimes neutrophils. The primary lesion is an eosinophilic lymphangitis, which results in eosinophilic abscesses, with occasional rosettes containing bacteria in their centres. Much experimental and epidemiological evidence, reviewed in this article, supports the suggestion that lechiguana is caused by an association of Pasteurella granulomatis (syn: Mannheimia granutomatis) and Dermatobia hominis.

Toxin production by Pasteurella granulomatis.

Pasteurella granulomatis (Pg) is a recently identified bacterium associated with proliferative fibrogranulomatous panniculitis (also called "lechiguana") in Brazilian cattle. Recent attempts to experimentally reproduce this disease have only been partially successful. We hypothesized that Pg may produce hemolysin(s) and/or cytotoxin(s) which could contribute to its pathogenicity in susceptible cattle. The objective of this study was to determine the presence and degree of hemolytic and leukotoxic activity of selected isolates of Pg. Either ovine or bovine blood agar plates were streaked with 1 of 7 Pg isolates, incubated at 37 degrees C +/- 1 C for 48 hours, and examined for hemolysis. Two of seven isolates showed hemolytic activity on bovine plates, while all seven showed hemolytic activity on ovine plates. By use of the CAMP reaction, involving simultaneous intersecting cultures of Staphylococcus aureus and Pg, all seven Pg isolates showed enhanced (positive CAMP) hemolysis within 24 hours on bovine blood agar plates. Preliminary results using tetrazolium (MTT) dye reductions with bovine neutrophils showed leukotoxicity in 13 of 16 Pg cultures. Alamar blue tests indicate leukotoxic activity for all 7 Pg isolates. We conclude that some Pg isolates have variable hemolytic and/or leukotoxic properties and that this variability (presence and/or degree) of these 2 properties may affect the relative pathogenicity of Pg in susceptible cattle.

Impalpable breast cysts: utility of cytologic examination of fluid obtained with radiologically guided aspiration.

PURPOSE: To evaluate the utility of cytologic analysis of fluid obtained from impalpable breast cysts by means of radiologically guided aspiration. MATERIALS AND METHODS: The authors retrospectively reviewed the reports of cytologic examinations of fluid obtained with sonographically or mammographically guided aspiration of 660 impalpable breast cysts in 583 women during 3 1/2 years. RESULTS: No malignant cells (541 cysts) or insufficient cellular material (86 cysts) was seen with cytologic examination of 95% of the aspirates. Atypical cells were seen with cytologic examination of fluid from 33 (5%) lesions. None of these 33 lesions were found to represent malignancy at the time of surgical excision (n = 9) or during clinical follow-up (n = 24). CONCLUSION: Routine cytologic examination is unnecessary if the fluid obtained with radiologically guided aspiration from impalpable breast cysts is not bloody.

Role of Pasteurella granulomatis and Dermatobia hominis in the etiology of lechiguana in cattle.

Attempts were made to reproduce bovine lechiguana, a disease associated with Dermatobia hominis and Pasteurella granulomatis infections. Suspensions of Pasteurella granulomatis were mixed with each of the following: saponin, oil adjuvant, ground Dermatobia hominis, or 5% mucin. Each preparation was inoculated into 6 cattle. Twelve more cattle, 6 of which received dexamethasone, were inoculated with bacterial suspension alone. Abscesses but no lechiguana was produced in all 36 cattle. After abscess regression, 12 cattle were reinoculated with a suspension of mouse-passed P. granulomatis. Only abscesses were produced. The intralymphatic inoculation of P. granulomatis in 6 cattle did not produce the disease. Eleven cattle infected naturally with D. hominis had lesions containing dead larvae. These lesions were inoculated with P. granulomatis. Nine cattle were experimentally infected with larvae of D. hominis that had been contaminated with the bacteria. No lechiguana lesions were produced in these 20 cattle. Six cattle with severe natural D. hominis infection were inoculated in the larval lesions with P. granulomatis. One developed lesions indistinguishable from those of natural lechiguana. The lesions regressed after treatment with chloramphenicol. D. hominis larvae and exudate from lesions caused by the fly were collected from 7 cattle on 3 farms and examined bacteriologically. P. granulomatis was isolated from the larvae and the exudate of a healthy calf from a farm where lechiguana had never been observed. These results suggest that P. granulomatis has a causal role in lechiguana, and that D. hominis may be a carrier of the bacterium. These observations suggest that lechiguana occurs when severe D. hominis lesions are infected with P. granulomatis. The apparent long incubation period, the negative results obtained in the other experiments, and also the infrequent occurrence of the natural disease suggest that lechiguana is a disease for which Koch's postulates are not easily fulfilled.

Conditions for transformation of Pasteurella multocida by electroporation.

Conditions for electroporation of plasmid DNA into Pasteurella multocida were determined for use in developing a cloning system to study virulence factors of P. multocida. The highest efficiency of transformation (1.25 x 10(7) cfu/micrograms DNA) was obtained when 7.6 x 10(10) cells of P. multocida strain R473 were electroporated at 12.5 kV/cm (10 ms, 5 ng of pVM109). Transformation efficiencies of cells prepared at mid-log-phase were approximately 0.5 log10 lower than early, late, or stationary phases. Neither pBR322 nor pUC-19 were able to transform strain R473 under these conditions, even when DNA concentrations were increased to 1 microgram. When pBR322 was ligated with a Pasteurella plasmid, pLAR-1, the hybrid was able to transform strain R473 at an efficiency between 4.5 x 10(2) and 8 x 10(4) cfu/micrograms DNA. Six strains of P. multocida including serotypes A, B, D, and E were transformed successfully.

Efficacy of various methods of confidential unit exclusion in identifying potentially infectious blood donations.

To determine the efficacy of various methods of confidential unit exclusion (CUE) among donors at increased risk of HIV exposure, we surveyed AABB institutional members on their experience with 3 CUE methods: ballot or barcode, completed at the time of donation, and call-back, performed by the donor after leaving the donor center. From June 1985 to December 1987, 5,049,883 donations at 48 donor centers were evaluable for analysis. The results of this survey suggest that ballot and barcode methods of CUE are important adjuncts to other donor screening procedures in identifying potentially infectious units, and that both of these methods are superior to the call-back system of unit exclusion.

Pasteurella haemolytica-like bacterium from a progressive granuloma of cattle in Brazil.

Three strains of a Pasteurella haemolytica-like bacterium were isolated from lesions of a progressive granuloma of cattle in southern Brazil. Their characteristics and their differentiation from P. haemolytica varieties and Actinobacillus lignieresii are described. The name "Pasteurella granulomatis" is proposed for this apparently new taxon.

Prevention of haemorrhagic septicaemia in buffaloes and cattle with a live vaccine.

Young cattle and buffaloes were vaccinated subcutaneously and intradermally with a live vaccine containing Pasteurella multocida serotype B:3,4. Twelve months after vaccination three of five young cattle in the subcutaneously vaccinated group and three of four in the intradermally vaccinated group were protected against serotype B:2 challenge. Eleven buffaloes vaccinated subcutaneously and two vaccinated intradermally survived the same challenge 13 months after vaccination.

Prevention of experimental haemorrhagic septicaemia with a live vaccine.

Pasteurella multocida serotype B:3,4 isolated from a fallow deer in England was used as a vaccine to prevent haemorrhagic septicaemia. The deer strain was less virulent for calves than typical serotype B:2 of haemorrhagic septicaemia strains. It elicited antibodies in cattle that protected mice against serotype B:2 infection. The live deer vaccine containing 2 X 10(7) viable organisms per dose was used to immunise calves. Six months after vaccination, five of six calves were protected against serotype B:2 challenge. Two calves challenged nine months after vaccination survived the same challenge. The live vaccine was more efficacious than an alum precipitated vaccine in protecting calves against B:2 challenge.

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.

Identification of serotypes of Haemophilus pleuropneumoniae by counterimmunoelectrophoresis.

Counterimmunoelectrophoresis, direct immunofluorescence and immunodiffusion procedures were used to serotype 15 strains of Haemophilus pleuropneumoniae isolated from the respiratory tract of pigs in southern Brazil. Antigens were prepared by extracting cultures with a saline solution or by the phenol-water method. Antisera were prepared in rabbits against serotypes 1, 2, 3 and 5. Thirteen of the isolates were type 5 and two were type 3. No differences were observed between the results obtained in serotyping with counter immunoelectrophoresis and direct immunodiffusion, but both procedures were significantly better than immunodiffusion except with the saline extracted antigen. Counterimmunoelectrophoresis was quicker, more sensitive and more easily performed than the other techniques.