Factors affecting the frequency of lipid body positive tubercle bacilli in human sputum

Mycobacterium tuberculosis (Mtb) is the causative agent of tuberculosis (TB). Mtb cells contain intracellular lipid bodies (LBs) in sputum and the levels vary between patients. Previous reports showed the essential role of nitric oxide (NO) in killing Mtb in vivo and that Mtb forms LBs in vitro upon NO treatment. These treated populations are tolerant to isoniazid and rifampicin, but the reasons for varing LB levels in vivo are not understood. The objective of this study was to determine the association between fractional exhaled nitric oxide (FeNO) concentrations with the proportion of LB[superscript +ve] tubercle bacilli in sputum. The majority of TB patients (65%) showed ≤ 20.6 ppb FeNO concentration. FeNO concentration was weak but significantly associated with the proportion of LB[superscript +ve] tubercle bacilli in sputum. FeNO concentration was also significantly associated with the proportion of LB[superscript +ve] tubercle bacilli among HIV[superscript +ve] P[superscript -] and HIV[superscript –ve] P[superscript +]/TB patients. High esosinophil count was significantly associated with FeNO concentration in both HIV[superscript –ve] and HIV[superscript +ve] /TB patients infected with intestinal parasite. The CAS and EAL Mtb spoligotypes were the dominant Mtb spoligotypes in Gondar. FeNO concentration was significantly associated with the proportion of LB[superscript +ve] tubercle bacilli among TB patients infected with the CAS Mtb spoligotype (p<0.01; r²=0.323) but not among patients infected with the EAL. The anti-microbial susceptibility pattern showed an 11.9% either mono or multi-drug resistance. The average proportion of LB[superscript +ve] tubercle bacilli among drug resistant TB patients was relatively higher than the corresponding drug sensitive TB patients. The proportion of LB[superscript +ve] tubercle bacilli was also higher among MDR-TB patients. The association between FeNO concentrations with the proportion of LB[superscript +ve] tubercle bacilli raises questions regarding L-arginine supplementation during TB treatment. The association of FeNO concentration with the proportion of LB[superscript +ve] tubercle bacilli among specific Mtb spoligotypes may reflect difference in NO tolerance.