Quality of sputa submitted at Kenyatta National Hospital Tuberculosis clinic laboratory and detection of Mycobacterium bacilli

Abstract

Introduction: Tuberculosis is a highly infectious disease caused by Mycobacterium tuberculosis. Sputum acid-fast bacilli (AFB) smear and culture still remain the most important tests for diagnosis of tuberculosis. Unfortunately, sputa has varied quality which can affect the AFB smear and culture results. Therefore, there is need to assess individuals put a specimens to maintain the validity of results. Methods: In a cross-sectional study between October and November 2010, we evaluated the sputa quality using Gram Stain. The quality outcome was then graded using Bartlett's Score and Murray and Washington's group. One hundred and thirty nine(139)patients with symptoms of tuberculosis such as chronic cough, weight loss, fever,and chest X-rays suggestive of TB were included in the study. A questionnaire was completed for each patient. The data collected was entered into MS Excel and later analyzed using STATA 10 and SPSS. Results: Bartlett's score had low quality sputum(below score 1) of 24% on first sputum, 14% on second sputum and 12% on third sputa. Murray and Washington's low quality sputum(group 1 to 3) was 36% on first sputum, 27% on second sputum and 18% on third sputum. There were 12(9%) patients positive for AFB on first sputum. On second sputum there was increase by 1 patient (8% increase) . On second sputum there was an increase of 2 patients in the high AFB (3+) outcome from 7 to 9(29%) increase. On third sputum there was fall on the highest AFB outcome to 8 from 9(11.%). Significant factors on the outcome of quality of sputa were age «0.0001), patient source-outpatient or inpatient(0.001), education-cu., history of fever<0.0001) and chronic illnesses<0.0001 ). Conclusion: There was marked improvement ,on quality on second sputa and also on outcome of AFB. This shows that the outcome of AFB smear depends on the quality of sputa, Therefore, there is need to maintain high quality sputa through good patient education and consistent checking of sputa in laboratories and report it alongside the results. BACKGROUND Tuberculosis infection and disease remain a great challenge world-wide today'. The effort to eradicate tuberculosis through early diagnosis, isolation, treatment and vaccination had great achievements in 1960s through 1970s.However, in 1980s with advent of HIV/AIDS , the gains sublimed and there was new surge of tuberculosis infections and a lot of anti-tuberculosis drugs resistance came into the fore2. Newer technologies to fight tuberculosis were and are still being developed. However, most molecular diagnosis are more of supplementation of traditional sputa smear and culture methods.Therefore, sputum still remains the most reliable diagnostic specimen for the disease28. Just like any other scientific diagnostic procedure, verifying the reliability and accuracy of results through quality control remains paramount". Sputum quality assurance is a difficult issue due to the fact that sputum is not universal like blood in all patientsand where available, is of varied quality degrees or grades from one individual to another. This has lead to development of grading systems for sputa quality so as to define the acceptable sputa for stain smears and culture30,31. It is also one of the procedures of ensuring quality control in tuberculosis clinic and laboratory to assess missed opportunities in diagnosis and whether expectoration instructions are being understood by patients". Despite this requirement being the practice in tuberculosis hospitals and research centres world over, it is rarely done in our local set-up and most prefer gross examination which is not reliable. There is need to determine the grades of quality of sputa in our set up in attempt to find how acceptable it is and to make it a regular practice to be part of smear results