Retrospective Analysis of Archived Pyrazinamide Resistant Mycobacterium tuberculosis Complex Isolates from Uganda-Evidence of Interspecies Transmission.

The contribution of Mycobacterium bovis to the proportion of tuberculosis cases in humans is unknown. A retrospective study was undertaken on archived Mycobacterium tuberculosis complex (MTBC) isolates from a reference laboratory in Uganda to identify the prevalence of human M. bovis infection. A total of 5676 isolates maintained in this repository were queried and 136 isolates were identified as pyrazinamide resistant, a hallmark phenotype of M. bovis. Of these, 1.5% (n = 2) isolates were confirmed as M. bovis by using regions of difference PCR analysis. The overall size of whole genome sequences (WGSs) of these two M. bovis isolates were ~4.272 Mb (M. bovis Bz_31150 isolated from a captive chimpanzee) and 4.17 Mb (M. bovis B2_7505 from a human patient), respectively. Alignment of these genomes against 15 MTBC genome sequences revealed 7248 single nucleotide polumorphisms (SNPs). Theses SNPs were used for phylogenetic analysis that indicated a strong relationship between M. bovis and the chimpanzee isolate (Bz_31150) while the other M. bovis genome from the human patient (B2_7505) analyzed did not cluster with any M. bovis or M. tuberculosis strains. WGS analysis also revealed multidrug resistance genotypes; these genomes revealed pncA mutations at positions H57D in Bz_31150 and B2_7505. Phenotypically, B2_7505 was an extensively drug-resistant strain and this was confirmed by the presence of mutations in the major resistance-associated proteins for all anti-tuberculosis (TB) drugs, including isoniazid (KatG (S315T) and InhA (S94A)), fluoroquinolones (S95T), streptomycin (rrs (R309C)), and rifampin (D435Y, a rare but disputed mutation in rpoB). The presence of these mutations exclusively in the human M. bovis isolate suggested that these occurred after transmission from cattle. Genome analysis in this study identified M. bovis in humans and great apes, suggesting possible transmission from domesticated ruminants in the area due to a dynamic and changing interface, which has created opportunity for exposure and transmission.

Mannosylated lipoarabinomannan in serum as a biomarker candidate for subclinical bovine tuberculosis.

BACKGROUND: Early and unambiguous detection of bovine tuberculosis (bTB), a significant disease of cattle worldwide, is necessary to control the spread of infection to other animals and humans. Current testing strategies are laborious, time consuming and heavily reliant on host responses that do not distinguish bTB from other mycobacteria. We report the presence of a pathogen signature, liparabinomannan (LAM), as a potential biomarker for bTB infection. FINDINGS: Fifty-five animals (uninfected [n = 33], bTb [n = 10] and exposed cases [n = 12]) from a well characterized bovine serum repository were screened for the presence of LAM using a commercially available ELISA. Analysis showed that LAM had a sensitivity of 100% and a specificity of 91.7% for bTB detection (bTB positive versus bTB exposed animals). CONCLUSION: LAM detection easily separated bTB infected animals from bTB exposed and negative controls. We propose that pathogen related markers, such as LAM, should be included with current testing strategies as a battery diagnostic for bTB.

Isolation of mycobacteria from clinical samples collected in the United States from 2004 to 2011.

BACKGROUND: Mycobacteria other than M. bovis may interfere with current bovine tuberculosis diagnostic tests resulting in false positive test results. As the prevalence of M. bovis decreases in the United States, interference from other mycobacteria play an increasingly important role in preventing the eradication of M. bovis. To identify mycobacteria other than M. bovis that may be interfering with current diagnostic tests, a retrospective study was performed to identify mycobacteria isolated from clinical tissues at the National Veterinary Services Laboratories between 1 January 2004 and 9 October 2011. RESULTS: During the study period, 2,366 mycobacteria other than M. bovis were isolated from samples submitted for clinical diagnosis of M. bovis. Fifty-five mycobacterial species were isolated during this time period. In cattle, M. avium complex, M. fortuitum/fortuitum complex, M. smegmatis, M. kansasii, and M. terrae complex were the predominate species other than M. bovis isolated from tissues submitted for culture. Mycobacteria other than M. bovis isolated from deer were predominantly M. avium complex, M. terrae/terrae complex, and M. fortuitum/fortuitum complex. CONCLUSIONS: These data provide information characterizing the species and relative prevalence of mycobacteria other than M. bovis that may interfere with current diagnostic tests.