Molecular Detection and Drug Resistance of Mycobacterium tuberculosis Complex from Cattle at a Dairy Farm in the Nkonkobe Region of South Africa: A Pilot Study

Abstract

Mycobacterium tuberculosis complex (MTBC) causes tuberculosis (TB) in humans and animals. We investigated the presence of MTBC in cattle milk and its drug resistance using polymerase chain reaction (PCR). Two hundred samples (100 mL each) were obtained from a dairy farm in the Nkonkobe region of South Africa. The samples were processed using the modified Petroff method. DNA was isolated using a Zymo Bacterial DNA kit and amplified using Seeplex® MTB Nested ACE assay. The Genotype® Mycobacterium tuberculosis-multidrug resistantplus (MTBDRplus) assay was used to perform drug susceptibility and detection of mutations conferring resistance to isoniazid (INH) and rifampicin (RIF). Eleven samples tested positive for MTBC DNA using the Seeplex® MTB Nested ACE assay. The Genotype® MTBDRplus assay showed that 10/11 samples were resistant to both INH and RIF i.e., multi-drug resistant (MDR). The most and least frequent rpoB mutations detected in RIF resistant samples were H526Y (9/10) and D516V (2/10) respectively. None of the INH resistant samples harbored mutations in the katG gene. However, all of them harbored the T8A mutation in the inhA gene. These results have clinical and epidemiological significance and calls for further studies and necessary actions to delineate the situation.

Isolation and molecular characterization of Mycobacterium tuberculosis complex isolated from raw milk in some dairy farms in Egypt

“…Rapid diagnosis will prevent the development of drug resistant M. tuberculosis [26]. Similar results were obtained by [27] who detected 11 (5.5%) positive samples. On contrast [28] failed to detect any positive cases among 30 examined milk samples.…”

Molecular detection of Mycobacterium bovis in cattle herds of the state of Pernambuco, Brazil

“…The prevalence of M. bovis DNA in milk samples ranges from 2 to 87 % according to different studies [ 14 – 20 ], which evaluated the mycobacteria presence by PCR. The different prevalence rates observed by them may be related to management characteristics [ 21 ], sampling methods [ 22 ] and disease-control measures adopted in each location [ 23 ].…”

“…The presence of M. bovis in milk samples is a concern because it is estimated that 41 % of all milk consumed in Brazil is not pasteurized [ 12 ] being a source of infection of human TB. Since the clinical symptoms of human TB caused by M. bovis are indistinguishable from those caused by M. tuberculosis [ 23 , 26 ], a detailed epidemiological investigation considering the patients eating habits and professional occupation must be performed by the health surveillance service to determine the TB causal agent. In Brazil, a study performed by Silva et al .…”

Zoonotic Aspects of Tuberculosis: Disease of the past or re-emerging zoonosis?

“…Drug and multidrug resistance has also been reported in M. bovis strains isolated both from humans and cattle (Cordova et al 2012;Kolditz et al 2010;Cavirani et al 2003;McLaughlin et al 2012;Silaigwana et al 2012). Transmission of such strains ( M. tuberculosis and M. bovis) to humans opens the possibility of their dissemination into the human food chain via unpasteurised milk, namely in developing countries where milk is largely consumed untreated (Sechi et al 2001).…”