Evaluation of sputum smear microscopy in the diagnosis of tuberculosis

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Date
2006-06
Authors
Noman Aldhubhani, Adel Hamood
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Abstract
Tuberculosis (TB) still remains a leading cause of mortality and morbidity with an estimation of 8.8 million new cases in the world. Among the TB diagnostic methods, acid fast bacilli (AFB) microscopic test method is still the most convenient due to its low cost and easy handling. The aim of this study v;as to evaluate the effectiveness of the AFB test in diagnosing TB cases. The study was carried out in 3 phases in 6 hospitals and 7 clinics in Penang, Malaysia. Phase One included a general observation on the set up of TB laboratories. Phase Two was aimed to assess the workload of TB laboratory technicians. The objective was to investigate if the workload would have any influence on the outcome of the AFB test. In Phase Three, the compentency of the technicians in performing the AFB test was assessed. Sputum smears prepared and examined simultaneously by the laboratory technicians and the researcher respectively were counter checked for its accuracy by a senior technician at the Hospital Pulau Pinang. The results obtained in Phase One indicated that, the set up of the TB laboratories was generally good. Seventy one percent ("71 %) of good quality samples were observed in hospitals. As for the clinics, the percentage of good quality samples did not exceed 38% except in clinic Kin which this percentage was 65%. In Phase Two, the workload of the technicians was found to be within the normal limits (i.e.11.29 smears per day and 45.2 smears per week). In Phase Three, 207 symptomatic cases were subjected to AFB test. Fifty-two were diagnosed as TB cases based on AFB and other investigations. AFB test detected only 13 of this 52 TB cases. It was concluded that the setup of TB laboratories was good. The collection procedure of sputum samples in hospitals was better than the clinics. The workload of TB technicians in conducting smear test was within normal limits. The proficiency of TB technicians wv.s good and no discrepancy was detected between them in terms of AFB results. The ability of AFB test to detect TB cases was increased when the sample quality was good. Following the proper way in conducting AFB test was recommended.
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