Novel hypertonic saline-sodium hydroxide (HS-SH) method for decontamination and concentration of sputum samples for Mycobacterium tuberculosis microscopy and culture.

Abstract

This study evaluated a new decontamination and concentration (DC) method for sputum microscopy and culture. Sputum samples from patients with suspected pulmonary tuberculosis (TB) (n=106) were tested using the proposed hypertonic saline-sodium hydroxide (HS-SH) DC method, the recommended N-acetyl-L-cysteine-sodium citrate-sodium hydroxide (NALC-NaOH) DC method and unconcentrated direct smear (Ziehl-Neelsen) techniques for the presence of mycobacteria using Löwenstein-Jensen culture and light microscopy. Of 94 valid specimens, 21 (22.3%) were positive in culture and were further characterized as Mycobacterium tuberculosis. The sensitivity for acid-fast bacilli (AFB) smears was increased from 28.6% using the direct method to 71.4% (HS-SH) and 66.7% (NALC-NaOH) using DC methods. Both concentration techniques were highly comparable for culture (kappa=0.794) and smear (kappa=0.631) for AFB. Thus the proposed HS-SH DC method improved the sensitivity of AFB microscopy compared with a routine unconcentrated direct smear; its performance was comparable to that of the NALC-NaOH DC method for AFB smears and culture, but it was methodologically simpler and less expensive, making it a promising candidate for evaluation by national TB control programmes in developing countries.

• Authors: Christian A Ganoza, Jessica N Ricaldi, José Chauca, Gabriel Rojas, César Munayco, Juan Agapito, Juan Carlos Palomino, Humberto Guerra
• Journal: Journal of medical microbiology (J Med Microbiol) Vol. 57 Issue Pt 9 Pg. 1094-1098 (Sep 2008) ISSN: 0022-2615 [Print] England
• PMID: 18719178 (Publication Type: Comparative Study, Evaluation Study, Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Saline Solution, Hypertonic
• Sodium Hydroxide

Topics

• Bacteriological Techniques
• Decontamination (methods)
• Humans
• Mycobacterium tuberculosis (isolation & purification)
• Saline Solution, Hypertonic (chemistry)
• Sensitivity and Specificity
• Sodium Hydroxide (chemistry)
• Specimen Handling (methods)
• Sputum (microbiology)
• Tuberculosis, Pulmonary (diagnosis, microbiology)