Preliminary Study of AFB Smear, Tuberculosis Cultivation and Drug Susceptibility Testing of Hypertonic Saline-Sodium Hydroxide-Treated Sputum Specimens
Keywords:
Hypertonic saline-sodium hydroxide, Drug susceptibility testing (DST), Multidrug resistant tuberculosis (MDR-TB)Abstract
Diagnosis and drug susceptibility testing (DST) of tuberculosis (TB) is necessary for proper treatment of TB patients. Preparation of sputum samples are important for performing concentrated acid-fast bacilli (AFB) smear, culture and both genotypic and phenotypic DST. Hypertonic saline-sodium hydroxide (HS-SH) has recently been developed for preparation of concentrated sputum smear and culture but no reports have yet been found on the use of this method for genotypic DST. This study was a preliminary study on concentrated AFB smear, culture, genotypic line probe assay (LPA) DST and phenotypic BACTEC MGIT 960 System DST of sputum specimens treated by hypertonic saline-sodium hydroxide (HS-SH) method. Of
227 sputa, each sample was divided into two equal portions. The paired samples underwent preparation by the HS-SH and N-acetyl-L-cysteine-sodium hydroxide (NALC-NaOH) methods. AFB smear, culture and DST were performed. The results revealed that AFB smear and culture between HS-SH and NALC-NaOH were in 100% agreement (Kappa=l.OO) and 94.3% agreement (Kappa=0.76), respectively. Most DST results obtained from each LPA and BACTEC MGIT 960
System methods were pan-susceptible pattern in 82,9% and 75,0% of all patterns, respectively,
while multidrug-resistant tuberculosis (MDR-TB) patterns were 7,9% and 5,7%, respectively. Both DST methods yielded an excellent concordance of isoniazid (INH), rifampicin (RMP) and
MDR-TB results. The percent agreement values of susceptibility for INH, RMP and MDR-TB
were 95.1%, 97.6% and 97.6%, respectively and the kappa statistic values were 0.88, 0.91 and
0,91, respectively. This preliminary study showed that AFB smear, culture, genotypic line probe assay (LPA) DST and phenotypic BACTEC MG IT 960 System DST can be performed on sputum specimens prepared by HS-SH method.
