Increased sensitivity of sputum microscopy with sodium hypochlorite concentration technique: A practical experience at RNTCP center

Abstract

Background:In revised national tuberculosis control program (RNTCP), microscopic examination of sputum for AFB plays an important role in the initial diagnosis of tuberculosis. Bacillary concentration after decontamination and liquefaction by 5% sodium hypochlorite is useful in providing increased sensitivity and safety for handling of specimen.Materials and Methods:In this cross-sectional, prospective study, carried out at NKP Salve Institute of Medical Sciences and RC, Nagpur, patients were included according to RNTCP criteria. One set of smears was made according to the RNTCP guidelines while another set was prepared by concentration after decontamination with 5% sodium hypochlorite. Both set of smears were stained according to RNTCP method and were screened by two observers separately to remove observer’s bias and graded according to the RNTCP guidelines. A total of 591 sputum samples from 219 patients were included in the study with 168 males (76.71%) and 51 females (23.28%).Results:A total of 77 samples (13.02%) from 34 patients were positive by routine method whereas by concentration method 119 samples (20.13%) from 49 patients were found positive diagnosing 15 additional patients. This rise of 7.11% in sputum positivity over routine is highly significant (P=0.001021, χ2=10.78) with 44.11% increase in diagnosed cases.Conclusion:There is a statistically significant rise in smear positive cases after concentration with 5% sodium hypochlorite solution. Considering its low cost, decontaminating and liquefaction properties with better sensitivity, this method is safe and can be of vital importance; at least for smear negative cases.

Evaluation of two pretreatment methods for the detection of Mycobacterium tuberculosis in suspected pulmonary tuberculosis

“…Literature indicates that the pretreatment of sputum using NaOCl can improve the sensitivity of the smear microscopy . In the current study, the sensitivity of the direct AFB smear and NaOCl centrifugation method was found to be 67% and 77%, respectively.…”

“…In overburdened countries, it is necessary to reduce the turnaround time (the time required for sputum smear preparation and microscopic examination) for sputum processing (typically <1 h) and this can be achieved by suitable pretreatment methods. Literatures indicate that the pretreatment of sputum with sodium hypochlorite (NaOCl) or phenol ammonium sulphate (PhAS) will decrease the turnaround time and enhance the efficiency of direct microscopy . The current study evaluated the performance of two pretreatment procedures for sputum smear microscopy (NaOCl and PhAS methods) and compared their effectiveness with Lowenstein‐Jensen (LJ) culture.…”

Comparative Study of Z N Staining vs. Flurochrome Staining and Impact of Sample Processing on Diagnosis of Tuberculosis from Various Clinical Samples

“…Although its implication will depend on availability of biosafety cabinet, centrifuge, requires standardization of process. But still we can hope its implication for better management of patients [9] [10].…”

Completing treatment for latent tuberculosis: patient background matters

“…Therefore, reducing the recommended number of specimens examined from three to two (particularly to two specimens collected on the same day) could probably benefit TB control programs (117,118). Performance of smear microscopy can be optimized by applying sputum processing with bleach, sodium hypochlorite or by use of overnight sedimentation and fluorescence microscopy (119)(120)(121) (122). In a study from Uganda, microscopic examination of 2 smears prepared from a single sputum specimen was as sensitive as standard two-specimen microscopy and that fluorescence microscopy (FM) using a light-emitting diode (LED) light source was more sensitive than conventional LM.…”