Abstract

Design: This was a cross-sectional study.

Setting: Moi Teaching and Referral Hospital a tertiary referral hospital in Kenya.

Materials and Methods: Adults and adolescents patients, diagnosed clinically and or radiologically to have smear negative pulmonary TB without any exclusion criteria and consenting for the study were enrolled. Patients inhaled 3% hypertonic saline through an ultrasonic nebuliser for 10 to 20 minutes then coughed 3-5 mls of sputum into a sputum container. The sputum specimen was taken to the laboratory for preparation, fixing, ZN staining and microscopy for AAFBs. Blood specimen was taken for HIV status at the diagnostic testing and counselling clinic. The patients were started on anti-tuberculosis medications and HIV positive patients referred to the HIV care clinic for clinical staging, baseline laboratory investigations including CD4 cell counts and follow-up.

Results: Two hundred and four patients were included in the final analysis. On sputum induction 99.3% patients produced sputum of which 21.02% yieded AAFBs on ZN staining. Among the HIV negative patients 28.85% had positive smear for AAFBs on sputum microscopy and 12.24% among the HIV positive patients yielded AAFBs. A total of 70.97% of the HIV positive patients had CD4 cell counts of less than 200 cells/mm3 and 29.03% had CD4 above 200 cells /mm3. The study showed an improved AAFBs yield on sputum induction which was significant among the HIV negative patients. There was a low AAFBs yield in the HIV-PTB coinfected patients with majority having CD4 cell counts below 200cells/mm3.

Conclusions: There was a significant AAFBs yield P(0.0036) on sputum induction in smear negative pulmonary TB in the HIV negative compared to HIV positive patients. HIV-PTB co-infection was associated with low AAFBs yield on sputum induction in smear negative PTB patients. Sputum induction in smear negative patients can improve the presumptive diagnosis of PTB by detection of AAFBs. A larger sample will be needed to determine CD4 levels influence on AAFBs yield in smear negative patients. This study recommends a universal sputum induction in smear negative PTB patients. Further local studies to determine the relationship between AAFBs yield and HIV /AIDS CD4 levels and the infectiousness risk of patients producing AAFBs on sputum induction will be needed.