[Investigation of the presence of Mycobacterium tuberculosis in the lymph node aspirates of the suspected tularemia lymphadenitis cases].

Recently reports of cervical tuberculous lymphadenitis and oropharyngeal tularemia which are the most common infectious causes of granulomatous lymphadenitis, have been significantly increased in Turkey. The differentiation of cervical tuberculous lymphadenitis and oropharyngeal tularemia is usually confusing on the basis of clinical and histopathological findings. Thus, in tularemia endemic areas, the patients are more commonly evaluated in terms of tularemia lymphadenitis leaving tuberculosis out. The aim of this study was to investigate the presence of Mycobacterium tuberculosis in cervical lymph node aspirates, obtained from tularemia suspected cases. A total of 105 oropharyngeal tularemia-suspected cases which were found negative for Francisella tularensis by bacteriological (culture), molecular (PCR) and serological (microagglutination) methods, were included in the study. The samples had been previously studied at National Tularemia Reference Laboratory, Turkish Public Health Institution, between 2009-2011. The study samples were evaluated in terms of M.tuberculosis by culture and real-time PCR (rtPCR) methods in the National Tuberculosis Reference Laboratory. Both Lowenstein-Jensen (LJ) medium and liquid-based MGIT (BD, USA) automated culture system were used for mycobacterial culture. Samples that yielded mycobacterial growth were identified as M.tuberculosis by immunochromotographic test (BD, USA). The lymph node aspirates of 65 patients who were F.tularensis PCR negative but antibody positive, were used as the control group. As a result, M.tuberculosis was found to be positive in 9 (8.6%) of 105 tularemia-negative lymph node aspirates, sent to our laboratory from different geographic regions for the investigation of tularemia. Six of the M.tuberculosis positive cases were male and the age range of the patients was 26-85 years. The presence of M.tuberculosis was detected only by culture in two samples, only by rtPCR in five samples and both by culture and rtPCR in two samples. M.tuberculosis was not identified in the control group specimens. Three of the samples which revealed tuberculosis, were from the tularemia endemic areas. In conclusion, the data of this preliminary study indicated that tuberculous lymphadenitis should be kept in mind in suspected tularemia cases and those patients should also be investigated simultaneously for the presence of tuberculous lymphadenitis.