" ' " ISOLATION OF RECURRENT MYCOBACTERIUM ISOLATES FROM SPUTUM SMEAR NEGATIVE RELAPSE AT THE

Rates of smear-negative pulmonary tuberculosis have been rising in countries with mv epidemics. The mortality rate among HfV-infected tuberculosis patients is higher than that of non infected tuberculosis patients, particularly for those with smear-negative pulmonary and extra pulmonary tuberculosis. Tuberculosis (TB) is an ancient infectious disease with high mortality rates. The World Health Organization (WHO) estimates that 2 billion people have latent TB, while another 3 million people worldwide die each year due to TB. The diagnosis of pulmonary tuberculosis (TB) relies on the bacteriological examination of sputum. However, microscopy of smears made directly from sputum has a low sensitivity and there is an urgent need for improved methods. This study intends to investigate the proportion of smear positive TB cases which were misdiagnosed as smear negative TB cases and also determine positivity rate amongst the smear negative relapses and the proportion of tubercle. The main objective of the study was to isolateMycobacterium tuberculosis from patients with recurring infections due to smear negative relapse amongst smear negatives, which are actually due to Mycobacterium tuberculosis referred at the Central Reference Laboratory Nairobi, Kenya. The study was conducted at the TB Central reference laboratory a referral public facility Located in Nairobi, Kenya, next to Kenyatta National hospital which cultures all retreatment cases in the whole country. The study was a prospective, cross-sectional descriptive study, which was under taken at TB reference laboratory as routine laboratory based activity. TB register was used to identify samples which were sputum smear negative tuberculosis relapse.4% Sodium hydroxide (NaOH) was used as a decontaminant agent and Lowenstein Jensen culture medium used as "gold standard" few as ten viable tubercle bacilli were detected, highly sensitive and specific test. p. nitro benzoic (PNB) acid was used as a bio-chemical test with Molecular method (DNA-HAIN), and all culture positive samples were genotyped to identify theMycobacterium species. Data was collected using appropriate structured laboratory culture request forms taking into consideration parameters of interest e.g. Age, Sex. Of the 273 initially confirmed direct Ziehl Neelsen (ZN) smear negative sputum specimens 47 (17%) were culture positive. The ZN sensitivity, specificity, Positive and Negative predictive values were 60%,92%,60% and 92% respectively after centrifugation with 4% Sodium hydroxide (p=O.OOl). Therewas a significant increase in sensitivity (X2=67.93), this means that a fifth of the samples screened using direct ZN method. However, using 4%NaOH (Modified Petroff's method) centrifugation method 47/273 (17%) specimens were smear positive for acid fast bacilli. DNA method identified the entire isolates, which are due to Mycobacterium Tuberculosis except one, which was due to environment Mycobacterium with 1Multi drug resistant sputum specimen. This study intends to inform policy makers on diagnosis of sputum smear negative relapse cases and suggest the way forward on better diagnosis for active case finding to the Ministry of Health through the TB Program.