Effect of Relative Centrifugal Forces and Centrifugation Times on Recovery of Mycobacterium Tuberculosis

Abstract

<p><strong>Background:</strong> Tuberculosis (TB) is one of the major cause of morbidity and mortality worldwide, affecting one third of world's population and the incidence is much higher in South-East Asia (India and China together account for nearly 40% of the global TB cases)</p><p><strong>Objectives:</strong> The current study was designed to evaluate the efficacy of relative centrifugal forces (RCFs) and various centrifugations times (CTs) on recovery of Mycobacterium tuberculosis (MTB) from sputum specimens pre-inoculated with MTB.</p><p><strong>Materials and Methods:</strong> For this study, direct acid fast bacilli (AFB) smear negative sputum specimens were randomly collected, which were further subjected to sterilization (by autoclaving at 121°C for 15 min) and then seeded with MTB. Afterwards, these sputum specimens were subjected to centrifugation (in a cold centrifuge) at various RCFs and CTs. After centrifugation, supernatants and sediments were inoculated on LJ media and incubated at 37°C with daily monitoring for 8 weeks.</p><p><strong>Results:</strong> In the current study, as the RCFs (6000 × g) and CTs (25 min and 20 min) were increased, the growth detection time exponentially decreased (9 and 11 days) and culture grades (4+) were increased when cultured from the sediments. However, the recovery rates of MTB from the supernatant fluids were constantly decreased as RCFs and CTs increased.</p><p><strong>Conclusion:</strong> The current study concluded that a higher RCF of 6000 × g and CTs of 20 and 25 min could effectively detect the tubercle bacilli from the sputum specimens more efficiently than other lower RCFs and CTs.</p>

Evaluation of six decontamination procedures for isolation of Mycobacterium avium complex from avian feces

“…All centrifugations were performed at 3000 x g for 15 min. Aliquots decontaminated with NaOH and H 2 SO 4 were centrifuged at 4 °C, and those treated with 1% CPC were centrifuged at 10 °C [ 31 , 32 ]. Supernatants were discarded, and pellets were resuspended in 1 ml of sterile distilled water.…”