Novel hypertonic saline-sodium hydroxide (HS-SH) method for decontamination and concentration of sputum samples for Mycobacterium tuberculosis microscopy and culture.
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.
Ganoza
Christian A
CA
Laboratorio de Microbiología Clínica, Instituto de Medicina Tropical Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Peru.
Ricaldi
Jessica N
JN
Laboratorio de Microbiología Clínica, Instituto de Medicina Tropical Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Peru.
Chauca
José
J
Laboratorio de Microbiología Clínica, Instituto de Medicina Tropical Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Peru.
Rojas
Gabriel
G
Laboratorio de Microbiología Clínica, Instituto de Medicina Tropical Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Peru.
Munayco
César
C
Laboratorio de Micobacteriología, Oficina General de Epidemiología, Ministerio de Salud, Lima, Peru.
Agapito
Juan
J
Programa Nacional para el Control de la Tuberculosis, Hospital Nacional Cayetano Heredia, Lima, Peru.
Palomino
Juan Carlos
JC
Mycobacteriology Unit, Prince Leopold Institute of Tropical Medicine, Antwerp, Belgium.
Guerra
Humberto
H
Laboratorio de Microbiología Clínica, Instituto de Medicina Tropical Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Peru.
D001431:Bacteriological Techniques; D003666:Decontamination / Q000379:methods*; D006801:Humans; D009169:Mycobacterium tuberculosis / Q000302:isolation & purification*; D012462:Saline Solution, Hypertonic / Q000737:chemistry*; D012680:Sensitivity and Specificity; D012972:Sodium Hydroxide / Q000737:chemistry*; D013048:Specimen Handling / Q000379:methods; D013183:Sputum / Q000382:microbiology*; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis / Q000382:microbiology*
D012462:Saline Solution, Hypertonic; D012972:Sodium Hydroxide