Cultural and biochemical characteristics of Mycobacterium paratuberculosis isolated from goats in Norway.

In Norway a variant of Mycobacterium paratuberculosis occurs which causes disease in goats but very seldom in sheep and cattle. Cultural and biochemical characteristics of this variant are investigated by comparing different pre-treatment methods and culture media for primary isolation and by subjecting a number of strains to different enzymatic and biochemical tests. Decontamination of materials with 5% oxalic acid and 0.1% benzalkonium chloride and culture on Dubos, Finleyson’s and Herrold’s medium was tested. The investigations showed that the combination oxalic acid decontamination/Dubos’ medium is most suitable for isolation of the goat-pathogenic variant.The morphology of the colonies was also most easily studied after culture on Dubos’ medium from material pre-treated with oxalic acid. The biochemical tests were found to be poorly suitable for the identification of M. paratuberculosis and for its differentiation from other mycobacteria.Mycobactin dependence for growth seems not to be absolute as a few goat strains produced growth on Dubos’ medium without mycobactin. However, growth was in all cases far better in the presence of mycobactin.     

Isolation of Mycobacterium paratuberculosis from sheep and cattle in Iceland.

Isolation of Mycobacterium paratuberculosis from sheep and cattle in Iceland. Acta vet. scand. 1979, 20, 191–199. — Culture experiments concerning the Icelandic variant of Mycobacterium paratuberculosis are described. Various decontaminating agents and culture media were employed and the colonial morphology of freshly isolated strains on different media described. The growth rate and culture requirements are compared with those of the Norwegian goat-pathogenic variant of M. paratuberculosis. For primary isolation modified Herrold’s medium gave the best results. However, on all the various culture media used, the growth of the Icelandic variant was much more sporadic than that of the Norwegian goatpathogenic variant. It is concluded that bacteriological culture is not useful for the diagnosis of Johne’s disease caused by the Icelandic variant of M. paratuberculosis.     

Certification of herds as free of Mycobacterium paratuberculosis infection: actual pooled faecal results versus certification model predictions

Dutch dairy herds closed for at least 3 years with no history of paratuberculosis were recruited for a study on herd-certification. One hundred dairy herds were tested for Mycobacterium paratuberculosis at 6-month intervals by pooled faecal culture (five individual animal samples per pool) with solid media. Ninety of the herds completed 9 herd tests and 10 herds dropped out of the study for reasons other than a paratuberculosis diagnosis. Of the 90 herds completing the full study, 61% eventually were found to be M. paratuberculosis-infected. The number of infected herds detected decreased with each round of testing. Assuming that all infected herds had been detected by the ninth herd test, the observed percentage of herds that were truly noninfected (P-free) after each round of testing was calculated. The observed P-free was compared to the predicted P-free based on a previously reported herd-certification model. The P-free predicted by the model was significantly different from the observed P-free. When a single assumption in the model was changed and a diagnostic sensitivity of 40–50% was selected, the predicted P-free closely approximated the observed P-free for the 90 Dutch dairy herds studied. The critical assumption that was changed for Version 2.0 of the model was within-herd infection prevalence for infected but test-negative herds after each round of serial testing. Model Version 1.0 had assumed a 50% decrease in within-herd prevalence but Version 2.0 assumed a stable within-herd prevalence. Culture of pooled faecal samples provides a high-sensitive, high-specific, low-cost test for herd-certification programs.     

Italian University System has to Match Educational Needs in Adherence to European Standards and Professional Scenario

The effect of a water-soluble fraction (WSF) of a non-pathogenic strain of Mycobacterium phlei was studied in bovine subclinical mastitis (SCM) by measuring the myeloperoxidase and acid phosphatase enzyme levels in the milk leukocytes. Forty-five cows were divided into three equal groups. Group I, consisting of 15 healthy cows, served as the control, whereas groups II and III each contained 15 cows with subclinical mastitis on the basis of a positive reaction in the California mastitis test (CMT). The cows in group II received 100 microg of WSF in 5 ml sterile phosphate-buffered saline, pH 7.4 (PBS) once only, while those in group III received 5 ml sterile PBS daily for 7 days, both treatments being given by the intramammary route. Observations were made up to 30 days after treatment (AT). The CMT of the healthy milk was negative (0), whereas it ranged between 1 and 2 points in SCM. The somatic cell count (SCC) increased significantly (p < 0.05) on day 3, then fell steeply from day 7 up to day 30 AT in the cows in group II. A steady decrease in the total bacterial count (TBC) was observed in the group treated with WSF but the bacterial counts remained high in the groups treated with PBS. The mean acid phosphatase level was enhanced by 119% on day 3 AT in group II but only by 18.7% in the cows in group III. The mean myeloperoxidase level was enhanced by 100% in the cows in group II but only by 18% in those in group III on day 3 AT. This significant reduction in the bacterial load in infected cows caused by intramammary infusion of WSF may be due to activation of the microbicidal activity of the neutrophils, but this requires confirmation.     

Prevalence of campylobacter in pigs during fattening; an epidemiological study

Summary

Numerous epidemiological reports implicate foods of animal origin as vehicles of human campylobacteriosis. Pigs are probably an important reservoir of campylobacter and a potential source of human infection. In order to improve our knowledge of the epidemiology of campylobacter in pigs, the prevalence of campylobacter and its contamination of feed were monitored in eight pig farms. Faeces samples of pigs aged 11 and 22 weeks, and samples of rectal, ileal and gastric content at a slaughterhouse were collected for bacteriological examination. On 5 farms, subsequent groups of pigs housed in the same stalls was sampled, too. A selection of the campylobacter isolates was characterized with a genetic typing method (RFLP). More than 85% of the sampled porkers were shown to be intestinal carriers of campylobacter at all stages of fattening. Subsequent groups of pigs housed in the same stalls were all carriers, too. The level of campylobacters in the faeces tended to decrease as the pigs got older. There was no difference in the frequency and level of infection with campylobacter between porkers on different farms. The feeding system (wet feed versus dry pellets) did not seem to influence the prevalence of campylobacter although wet feed gave lower counts of Enterobacteriaceae in the faeces.

RFLP‐typing showed a high diversity of campylobacter strains at each sampling on the farm. Similarities were seen between strains isolated during two subsequent samplings of the same group of pigs, but not between strains isolated on the same farm from subsequent groups of pigs housed in the same stall. This suggests that the piglets were already infected at a young age on the breeding farm.     

Tissue localisation of Mycobacterium avium subspecies paratuberculosis following artificially induced intracellular and naked bacteraemia

Mycobacterium avium subspecies paratuberculosis (MAP) is the causative agent of Johne's disease or paratuberculosis, a chronic enteritis of ruminants. While Johne's disease is primarily expressed in the gastrointestinal tract, isolation of MAP from extra-intestinal tissues indicates that microbial dissemination via the haematogenous route may occur during the infection. This study examined the movement of peripheral blood mononuclear cells (PBMCs) infected with MAP and the dissemination of MAP following mycobacteraemia induced by IV inoculation over a time frame of 3 days.     

Longevity of Mycobacterium bovis in brushtail possum (Trichosurus vulpecula) carcasses,and contact rates between possums and carcasses

Abstract

AIM: To determine, for a variety of environmental conditions, how long Mycobacterium bovis might remain viable inside the carcass of a brushtail possum (Trichosurus vulpecula) that died of bovine tuberculosis (Tb), and to measure the rate of contact between free-ranging possums and possum carcasses.

METHODS: Lesions of M. bovis were simulated by inoculating excised spleens weighing 0.5–1 g with 0.2 mL liquid culture containing approximately 5 x 10⁷ cfu M. bovis/mL. Simulated lesions were inserted into possum carcasses (n=48) at the peripheral lymph nodes. Carcasses were placed in the field at two sites (a tussock grassland and a podocarp-broadleaved forest site) and in two seasons (summer and winter) for up to 62 days. Survival rates of M. bovis were estimated by sampling the simulated lesions over time, and culturing the recovered lesion to determine if any viable M. bovis bacteria were present.

The time taken for a free-ranging possum to first encounter a dead possum in its home range was estimated by live-trapping possums and fitting them with proximity loggers (n=13). A ‘contact’ was recorded if these possums came within 40–50 cm of proximity loggers fitted to possum carcasses.

RESULTS: There were strong seasonal and site effects in the survival rate of M. bovis in possum carcasses. In the grassland habitat, no viable bacilli were cultured from any carcass after 3 days in summer, whereas in winter all samples were culture-positive for the first 20 days, and some were still positive after 27 days. The survival rates for forest habitat were intermediate between the results for grassland, and there were no culture-positive carcasses after 9 days in summer or 27 days in winter.

In summer, infected carcasses (n=6) were first encountered by possums a mean 1.9 (range 0.4–6.7) days after placement.

CONCLUSIONS: Possum carcasses were contacted by free-ranging possums within the period that viable M. bovis were shown to survive in a carcass. The risk of such infection is likely to be most significant in winter or in areas with microhabitats where the survival of M. bovis is high. However, the generally low survival rate of M. bovis in possum carcasses and the low frequency of possum-to-carcass contacts indicate this route of transmission alone could not maintain Tb in a possum population.     

Examination and control of lameness in dairy herds

Extract

Lameness is a significant problem in dairy herds in New Zealand. It affects production and causes cows to lose weight. If antibiotics are used, milk has to be withheld from the vat. Cows may go into extended anoestrus and some which fail to conceive have to be culled. Even in its mildest form lameness is an inconvenience to the normal management of the herd.     

Mange in pigs: A survey

Extract

Mange in pigs caused by Sarcoptes scabiei var. suis is reported to be common in New Zealand, but, to the writer's knowledge, no investigation has been made of the number of infested farms in any area.     

Tuberculosis in alpaca (Lama pacos) on a farm in Ireland. 1. A clinical report

This case report describes tuberculosis (TB) due to infection with Mycobacterium bovis (M. bovis) in alpaca (Lama pacos) on a farm in Ireland. Two severely debilitated alpaca were presented to the University Veterinary Hospital, University College Dublin in November 2004. Bloods were taken, and haematology and biochemistry results were indicative of chronic infection. Radiological examination showed evidence of diffuse granulomatous pneumonia suggestive of tuberculosis. On necropsy there were granulomatous lesions present throughout many body organs including lung, liver, kidney, intestine as well on peritoneum and mesentery. Culture of acid-fast bacilli from lesions led to a diagnosis of tuberculosis due to M. bovis. The use of intradermal skin testing proved inefficient and unreliable for ante mortem diagnosis of tuberculosis in alpaca. Infection due to M. bovis should be considered among the differential diagnoses of debilitating diseases in alpaca, particularly those farmed in areas known to be traditional black spots for tuberculosis in cattle.