The quality of sputum smear microscopy diagnosis of pulmonary tuberculosis in Dar es Salaam, Tanzania

Abstract

This study was carried out to determine the rate of agreement or disagreement of microscopy reading and culture positivity rate among smear positive and negative specimens between peripheral tuberculosis diagnostic centres (PDCs) and Central Reference Tuberculosis laboratory (CTRL). In this study 13 PDCs in Dar es Salaam, Tanzania were involved. Lot Quality Assurance Sampling (LQAS) method was used to collect 222 sputum smear slides. A total of 190 morning sputum specimens with corresponding slides were selected for culture. First readings were done by technicians at PDCs and thereafter selected slides and specimens were sent to CTRL for re-examination and culture. Culture results were used as a gold standard. Of 222 slides selected, 214 were suitable for re-examination. Percentage of agreement of smear reading between PDCs and CTRL was 42.9% and 100% for positive and negative slides, respectively. Measure of agreement (Kappa statistic) was 0.5, indicating moderate agreement. Of 190 samples cultured, percentage of agreement between smear reading from PDCs and CTRL was 37% and 88.9% for smear positive and negative slides, respectively. Kappa statistic was 0.3 indicating poor-fair agreements. Comparison of smear reading from PDCs with culture showed sensitivity of 36.9% and specificity of 88.9%. Comparison of smear readings from CTRL with culture results showed sensitivity of 95.6% and specificity of 98.6%. In conclusion there was inadequate performance in diagnosis of TB using smear microscopy among peripheral diagnostic centres in Dar es Salaam. This calls for immediate and rigorous measures to improve the quality of smear microscopy. It is therefore important to strengthen the capacity of laboratory personnel in smear microscopy techniques through supportive supervision and training.

Knowledge and healthcare seeking behaviour of pulmonary tuberculosis patients attending Ilala district Hospital, Tanzania

“…A quarter of the interviewees came to the hospital within a month and were initiated on treatment while about half of the population were diagnosed and began treatment from the 5 th -16 th week after the onset of symptoms. Some of the reasons for this delay may be the slow progression of symptoms, financial constraints preventing early treatment, seeking treatment from sources other than the conventional health care facilities, and atypical presentation of signs and symptoms leading to initial misdiagnosis (Mfinanga et al, 2007). It has already been shown that a time lag of about 30 weeks was common among TB patients in Dar es Salaam, Tanzania (Kasimbazi, 1985).…”

“…This means, the sputum sample results were not considered very reliable. In a different study, Mfinanga et al (2007) reported that about one fifth of TB patients in Dar es Salaam are misdiagnosed as non cases and therefore not treated.…”

Diagnosis of Tuberculosis by Trained African Giant Pouched Rats and Confounding Impact of Pathogens and Microflora of the Respiratory Tract

“…ovel methods for rapid diagnosis of tuberculosis (TB) are urgently needed to complement smear microscopy, which has low sensitivity (20), and culture, which is slower and requires specialized laboratory conditions not available in resourceconstrained settings. Trained African giant pouched rats (Cricetomys gambianus) possess profound potential for rapid detection of TB with higher sensitivity and specificity (38).…”

Association of sputum conversion and outcome with initial smear grading among new smear positive Tuberculosis patients in a Tertiary Health Facility, South East Zone, Nigeria

“…9,10 Therefore, sputum AFB conversion is a suitable indicator to evaluate the treatment response. 11 The grading of a positive smear reflects the extent of lesion in a particular patient or size of cavitations as well as being directly proportional to the infectiousness of the case.…”