agar and Tuberculosis--Bovine

In studies of Mycobacterium bovis infection in animals a definitive diagnosis requires the isolation of the organism. However, the optimum conditions for the primary isolation of M. bovis have not been determined. The aim of this study was to determine for primary isolation of M. bovis, (a) the incubation time required to achieve maximum sensitivity (i.e., the number of positive samples identified), (b) the effect of decontaminants on bacterial growth rates, and (c) the influence of media and the number of slopes of media on the number of positive samples detected. Two agar-based media, modified Middlebrook 7H11 (7H11) and tuberculosis blood agar (B83), and an egg-based medium, Stonebrink's (SB) were compared. Three decontaminants, 2% (w/v) sodium hydroxide (NaOH), 0.75% (w/v) and 0.075% (w/v) cetylpyridinium chloride (CPC, also called hexadecylpyridinium chloride, HPC) and 0.5% (w/v) benzalkonium chloride (BC) were evaluated against treatment with sterile distilled water. The inoculated media slopes were incubated for up to 15 weeks. Colonies first appeared after 2 weeks on all media types and 75% of positive slopes were identified by 8 weeks. An incubation time of 15 weeks was required to identify all positive samples. The slowest growth was associated with inocula that contained the fewest viable bacilli. The time to the appearance of colonies was influenced by medium type: the median time to detection of colonies was 28 days on 7H11 and B83, and 36 days on SB. However, SB returned the greatest number of positive samples. Decontamination procedures increased the minimum incubation time required to detect positive cultures, probably due to the toxic effect of the decontaminants. Increasing the number of inoculated slopes resulted in an increased number of positive samples and a decreased time to the detection of colonies. Overall, the detection of M. bovis was significantly influenced by the choice of media, the decontaminant and the duration of incubation of cultures.

Topics: Agar; Animals; Bacteriological Techniques; Cattle; Cetylpyridinium; Culture Media; Decontamination; Mycobacterium bovis; Sodium Hydroxide; Tuberculosis, Bovine

Suspect tuberculous lesions from 116 cattle were examined histologically and cultured for Mycobacterium bovis using 5 different media. The media used were: B83, an agar medium incorporating bovine blood and sodium pyruvate; Middlebrook's agar; 2 variations of Stonebrink's medium; Löwenstein-Jensen medium. The B83 medium and a modification of Stonebrink's medium which had a lowered concentration of malachite green were most successful, detecting 95.2% of tuberculous animals when used together. The B83 medium detected isolates approximately 1 week earlier and had more colonies than the Stonebrink's modification. A combination of 2 slopes of B83 and 2 slopes of modified Stonebrink's medium is recommended for routine culture of samples.

Topics: Agar; Animals; Cattle; Culture Media; Mycobacterium bovis; Tuberculosis, Bovine

Topics: Agar; Animals; Antigens, Bacterial; Birds; Cattle; Chemical Precipitation; Culture Media; Humans; Mycobacterium bovis; Mycobacterium tuberculosis; Tuberculosis; Tuberculosis, Avian; Tuberculosis, Bovine

Topics: Agar; Animals; Antibodies; Bacillus; Blood; Cattle; Clinical Laboratory Techniques; Complement Fixation Tests; Hemagglutination Inhibition Tests; Immunodiffusion; Mycobacterium bovis; Precipitin Tests; Rabbits; Tuberculin; Tuberculin Test; Tuberculosis; Tuberculosis, Bovine

Topics: Agar; Animals; Bacillus; Bacteriological Techniques; Cattle; Cresols; Culture Media; Diagnosis, Differential; Humans; Lacticaseibacillus casei; Mycobacterium bovis; Mycobacterium tuberculosis; Niacin; Nicotinic Acids; Tuberculosis; Tuberculosis, Bovine