Background: Tuberculosis, caused by M. tuberculosis, is the deadliest disease causing 3 rnmillion annual deaths globally. M. tuberculosis is an intracellular pathogen that survivesrnandrn rnreplicates within cells, primarilyrn rnmacrophages. An important part of the host defensernagainst tuberculosis is nitric oxide and other reactive intermediates produced byrnactivated macrophages. M. tuberculosis differ in their strain types, susceptibility to thernconventional anti Tb drugs and to the effect of nitric oxide which in turn may influencernclinical outcome of active tuberculosis patients.rn Objectives: The aim of this project, therefore, was to investigate strains differences, therneffect of the potent RNI, NO (nitric oxide), and the convectional anti-Tb drugs on thernclinical isolate of M. tuberculosis, in vitro, from patients receiving arginine (Nitric oxide)rnin the form of peanuts in an ongoing clinical trial study and to correlate the findings withrnclinical outcome of those subjects.rnMethods: Both, prospective and retrospective study had been conducted to investigaternthe molecular epidemiology, NO (nitric oxide) susceptibility and anti-mycobacterialrnsensitivity patterns of the clinical isolates MTB in order to asses correlation of results tornclinical outcome of active tuberculosis patients. Smear-positive sputums from 180 studyrnparticipants were cultured to obtain pure clinical isolates. Standard PCR method andrnspoligotyping were done to identify the strains of M. tuberculosis. The isolates were alsorntested for their drug susceptibility pattern using proportion method. The in vitro effects ofrnRNI and susceptibility profile of those isolates were determined after series ofrnoptimizations experiments using DETA/NO (potent nitric oxide donor chemical). rnResults: Of 176 smear-positive TB patients enrolled, 93 (52.8%) were female, 68 (38.6%)rnwere HIV sero-positive and the mean age was 27.5 (SD = 9.55; R = 15 â€“ 59). HIV seroprevalencernrnwas high among age groups between 25 â€“ 45 yrs of age (P=0.000). Of 176rnsmear-positive sputa 67.6% were culture positives. Conventional PCR of isolatesrnrevealed that all strains belong to M. tuberculosis. Spoligotyping was done for 108rnstrains, of which 83 (76.8%) were clustered in to 4 major M. tuberculosis families beingrnCAS families the dominant ones (43%). The remaining 25 (23.2%) were unique and nornnon-tuberculos mycobcteria was detected. The overall proportion of drug resistantrnstrains was 14.3% (14/98), poly-resistant 1% and no MDR-strains were identified. rnThe clinical strains generally showed variability in percent survival to NO exposure withrnmedian survival rate of 14.1% (IQR, 3.0 â€“ 30.3%), and exposure of strains to 1mM ofrnDETA (NO donor) for 24hrs significantly reduced (P=0.000) the bacterial colonyrnforming units (cfu). In logistic regression analysis, nitric oxide survival rate of clinicalrnisolates was significantly associated with some of the clinical conditions of the patientsrnlike BMI (kg/mrn2rn) (P= 0.04), smear conversion (P= 0.03) and cure rate (P= 0.04). rnConclusions: Mycobacterium tuberculosis was the only mycobacterial strain foundrnamong consecutive smear positive isolates, the rate of anti-microbial resistance wasrnhigh. Patients carry drug resistant strains significantly exhibited decreased cure rate andrnsmear conversion rate at 2 months. Clinical isolates of M. tuberculosis exhibiting nitricrnoxide resistance showed significantly more anti mycobacterial drug resistance comparedrnto nitric oxide susceptible strains. Further research is needed on the importance and usernof nitric oxide to prevent and control of the spread of tuberculosis.