[Investigation of Mycobacterium bovis subsp. bovis among the strains of Mycobacterium tuberculosis complex isolated in Düzce Province, Turkey].

Throughout the history of mankind, tuberculosis (TB) has caused serious illness and still continues to do so. Archaeobiological studies indicated that TB in humans dates back to 4000-8000 BC, and cases were shown to be due to Mycobacterium bovis subsp.bovis rather than Mycobacterium tuberculosis. Moreover, this situation was thought to begin with domestication of animals, consumption of their milk, and living together in the same environment with them. Over time, with the consumption of boiled milk and with the establishment of separate animal shelters, M.bovis subsp. bovis infection began to be seen rarely. Today, M.bovis infection is mostly transmitted from animals to humans and very rarely from humans to other humans. The most significant means of transmission of the infection are to the gastrointestinal tract via consumption of raw milk and to the respiratory system via droplet infection from the animals with disease. In this study, it was planned to investigate the cause of occurrence of TB in cattles in Düzce in the past few years along with the presence of bovine type TB in cases of human tuberculosis. We aimed to carry out subtype determination of the M.tuberculosis complex (MTBC) strains isolated in our mycobacteriology laboratory between the years 2004-2014, and evaluate the clinical and sociodemographic data of patients in whom M.bovis subsp. bovis was detected. The strains that were selected for the study have been isolated from radiometric BACTEC™ 12B broth and/or Löwenstein-Jensen (LJ) media between 2004-2009, and BACTEC™ MGIT™ (Mycobacteria Growth Indicator Tube) and/or LJ media between 2009-2014 periods. The GenoType MTBC Kit (Hain-Lifescience GmbH, Germany) was used in the study for determination of the subspecies. Extraction and amplification of DNA and hybridizations were performed according to test procedure in order to investigate the presence of subtypes of the MTBC species in skimmed milk from collections stored at -20°C. In the study, MTBC strains isolated from 220 patients (217 adults, 3 children; 145 male, 75 female) were evaluated and 217 (98.6%) of them were identified as M.tuberculosis/M.canettii and three (1.4%) as M.bovis subsp. bovis. When the distribution of the isolates were evaluated according to the years, it was noted that three (2.8%) cases out of 106 patients within the last three years, were found to be infected with M.bovis subsp. bovis, while none were detected in the 114 cases from the previous years. This data emphasized a parallel course with the reported cases of cattle tuberculosis in recent years. The risk factors, clinical and sociodemographic features, treatment process, outcomes, and mycobacteriological findings of those three patients were reviewed. Accordingly, the first case was a 63-year-old female with diabetes mellitus and chronic renal failure, who was dealing with animal husbandry. She was diagnosed as miliary TB on July 2012 and completed her treatment schedule. The second case, who was also dealing with animal husbandry was a 85-year-old male with prostate carcinoma. This case was diagnosed as pulmonary TB on December 2013, however he has quited the treatment and died two months later. The third case, a 27-year-old female was admitted to the hospital with a cervical mass that developed when she was working as a seasonal laborer. She was diagnosed to have lymph node TB in September 2014 and completed her treatment schedule. The strains isolated from the first and third cases were found to be susceptible to streptomycin (STR), isoniazid (INH), rifampicin (RIF) and ethambutol (EMB), while the strain isolated from the second case was susceptible to STR, INH and RIF, but resistant to EMB. All of the three isolates were resistant to pyrazinamide. As a result, it was concluded that large-scaled and attentive monitoring of TB infections in animals, as well as searching for M.bovis subsp. bovis in TB cases, especially in high-risk groups would be essential for an accurate diagnosis.