Phenol ammonium sulphate basic fuchsin staining of sputum in pot for the detection of acid-fast bacilli.

BACKGROUND & OBJECTIVES: Improper practices of making direct smears of sputum for detection of acid-fast bacilli (AFB) and of disposing sputum cups are hazardous. The present study was undertaken with the objective to stain sputum samples in their containers by 'phenol (10%) ammonium sulphate (4%) basic fuchsin (2%) solution' and to decolourize and counterstain their smears for detection of AFB- (henceforth called pot method) and to compare the smear results of pot method with the standard Ziehl-Neelsen (ZN) method. METHODS: A total of 575 selected sputum samples from pulmonary tuberculosis patients were stained by the standard ZN and pot methods and the proportions of AFB positive smears were compared. RESULTS: Of the 575 samples, 126 were AFB positive for both the staining methods and the difference was not statistically significant. Pot method missed 9 ZN positive smears (8 scanty and one 1+) and ZN method missed 9 pot positive smears (9 scanty) and the difference was not significant. High grade smears (3+) were seen more in pot method (42) than in ZN method (25) and the difference was significant. INTERPRETATION & CONCLUSION: Our findings showed that pot method was comparable to standard ZN method and had many advantages. Pot method can be explored further for the detection of AFB in sputum samples obtained from pulmonary tuberculosis suspects.

Course of action taken by smear negative chestsymptomatics a report from a rural area in south India.

Objective: To evaluate adherence to diagnostic algorithm of Revised National Tuberculosis Control Programme (RNTCP) and course of action taken by smear-negative chest symptomatics (CSs). Method: Interviewing smear-negative chest symptomatics. Results: Of the 423 smear-negative CSs interviewed, 85 (20%) were not prescribed antibiotics and only 133 (39%) received it for more than seven days. Of the 148 patients with persistence of symptoms, 83 (56%) returned for further investigations and only 39% were X-rayed. Main reasons for not returning were: ‘not aware’ or ‘consulted another health provider.’ Conclusion: Strict adherence to diagnostic algorithm and proper counselling of patients are important for diagnosing smear-negative pulmonary tuberculosis (PTB) cases.

Proficiency to read sputum AFB smears by senior tuberculosis laboratory supervisors under training at a reference laboratory in India.

Background: A national reference laboratory imparting training on sputum AFB smear microscopy to fresh Senior Tuberculosis Laboratory Supervisors (STLS). Aim: To assess the proficiency of STLSs under training to read sputum AFB smears. Methods: Each of 342 trainees read the same set of 15 to 20 Ziehl Neelsen stained smears in a blinded fashion on day– 1 and on day-15 of the training programme. The smear results were matched with the original results. Observations: The sensitivity, specificity, positive predictive value and negative predictive value of smear reading were 75%, 88%, 93%, 63% and 94%, 99%, 99%, 89% respectively on day-1 and day –15. Conclusion: The sensitivity to read sputum AFB smears by fresh STLSs with little or no experience increased from 75% to 94% during the carefully planned training programme; the specificity increased from 88% to 99%. The study highlights the importance of training in improving the microscopy results.