Pre-analytical factors affecting time to detection of Mycobacterium tuberculosis by culture using BACTEC MGIT 960
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Abstract
Tuberculosis (TB) is contagious bacterial infection caused by Mycobacterium tuberculosis which is a global public health problem. Cultivation is still a gold standard method for TB diagnosis at the present time. This method should be considered in pre-analytical phase that affected on the accuracy and precision of results. The aim of the current study was evaluation of pre-analytical factors that affected detection time of M. tuberculosis using BACTEC MGIT 960 culture. The data of mycobacterial cultures from sputum samples were retrospectively reviewed from the records of TB laboratory of the office of Disease Prevention and Control 3rd, Nakhon Sawan in fiscal year 2017. Of 177 sputum sample data, pre-analytical factors showed that the average of volume was 4.3 ml and 65.0% of sample volumes were more than 5 ml. Most of the samples were low quality which were found in 63.3 of samples. The positive and negative AFB results were 91.0 and 9.0, respectively. The average of time intervals that the samples were collected to culture was 5.0 days and most of time intervals were more than 3 days at 69.5% of samples. 89.3% of sample were transported by hospital cars. For sample refrigeration during transportation, the samples were refrigerated 55.9% while 44.1% of samples had no refrigeration. Comparison between pre-analytical factors and detection time of M. tuberculosis by BACTEC MGIT 960 culture showed that only AFB results related to detection time with statistical significance (P-value < 0.001) whereas other factors had no relation. In conclusion, the pre-analytical factors that had no effect on the detection time of TB culture were minimum 2 ml of sputum volume, storage of sputum up to 7 days, hospital car and parcel transportation of sputum sample and refrigeration during transportation. The guideline developing of sputum culture for TB should still control pre-analytical factors that affect the quality of sample before sending to analysis in laboratory, however the guideline should be appropriate for each area condition.
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References
2. American Thoracsic Society. Diagnostic standards and classification of tuberculosis in adults and children. Am J Respir Crit Care Med 2000; 161: 1376-95.
3. Rashid I, Mabuza LH, ovender I, Pretorius D. Volume of sputum to detect acid-fast bacilli as a measure of quality for the diagnosis of pulmonary tuberculosis at the Dr George Mukhari Hospital, South Africa. Afr J Prim Health Care Fam Med 2011; 3: 240.
4. Warren JR, Bhattacharya M, De Almeida KN, Trakas K, Peterson LR. A minimum 5.0 ml of sputum improves the sensitivity of acid-fast smear for Mycobacterium tuberculosis. Am J Respir Crit Care Med 2000; 161(5): 1559-62.
5. McCarter YS, ROBINSON A. Quality evaluation of sputum specimens for mycobacterial culture. Clin Microbiol Infect Dis 1996; 105: 769-73.
6. Umesh H, Nitin S. Correlation of various criteria for sputum quality with AFB smears positivity. Pak J Med Sci 2013; 3: 30-4.
7. World Health Organization. Laboratory services in tuberculosis control part II: microscopy. Geneva: WHO; 1998.
8. International Union Against Tuberculosis and Lung Disease. Technical guide: sputum examination for tuberculosis by direct microscopy in low income countries. 5th ed. Paris: IUATLD; 2000.
9. Yoon SH, Lee NK, Yim JJ. Impact of sputum gross appearance and volume on smear positivity of pulmonary tuberculosis: a prospective cohort study. BMC Infectious Diseases 2012; 12: 172.
10. McCarter YS, ROBINSON A. Quality evaluation of sputum specimens for mycobacterial culture. Clin Microbiol Infect Dis 1996; 105: 769-73.
11. Curione CJ, JR, Kaneko GS, Voss JL, Hesse F, Smith RF. Gram stain evaluation of the quality of sputum specimens for mycobacterial culture. J Clin Microbiol 1977; 5: 381-2.
12. Pang Y, Su B, Zheng H, Zhang Z, Ma A, Wang Y, et al. Factors associated with missed detection of Mycobacterium tuberculosis by automated BACTEC MGIT 960 System. Biomed Res Int 2016; 2016: 5972021.
13. Huang TS, Chen CS, Lee SS, Huang WK, Liu YC. Comparison of the BACTEC MGIT 960 and BACTEC 460TB systems for detection of mycobacteria in clinical specimens. Ann Clin Lab Sci 2001; 31(3): 279-83.