Assessment of panel slides prepared by phenol ammonium sulphate and NALC methods for proficiency testing.

Background: Existing methods for the preparation of panel slides necessitate handling high-grade acid-fast bacilli positive sputum samples.

Objective: To compare panel slides prepared using the phenol ammonium sulphate sediment (PhAS) method with those prepared using the N-acetyl-L-cysteine (NALC) method in proficiency testing.

Methods: Pooled sputum specimens of known smear-positives and -negatives were divided into two parts: one part was used for preparing panel slides using the NALC method and the other using PhAS, a non-hazardous method.

Pot method for storage & detection of acid-fast bacilli from sputum samples.

Background & Objectives: Sputum acid-fast bacilli (AFB) microscopy services are not available in all health facilities. Alternative procedures are needed to transport sputum samples to the diagnostic centres for detection of AFB. The objective of the present study was to evaluate sputum smears made by pot-method with the direct smears made immediately after sputum collection by Ziehl-Neelsen (ZN) method.

Phenol ammonium sulphate basic fuchsin staining of sputum in pot for the detection of acid-fast bacilli.

Background & Objectives: Improper practices of making direct smears of sputum for detection of acid-fast bacilli (AFB) and of disposing sputum cups are hazardous. The present study was undertaken with the objective to stain sputum samples in their containers by 'phenol (10%) ammonium sulphate (4%) basic fuchsin (2%) solution' and to decolourize and counterstain their smears for detection of AFB- (henceforth called pot method) and to compare the smear results of pot method with the standard Ziehl-Neelsen (ZN) method.

Methods: A total of 575 selected sputum samples from pulmonary tuberculosis patients were stained by the standard ZN and pot methods and the proportions of AFB positive smears were compared.

Contamination of stored sputum AFB smears with environmental mycobacteria.

To check the quality of stains and the acid-fast bacilli (AFB) staining procedure, a sample of 73 AFB-negative sputum smears selected systematically from a microscopy centre was rechecked before and after restaining with the same AFB staining method at a reference laboratory. Respectively 0 and 30 showed AFB before and after restaining. Detection of AFB after restaining in 30 of 73 negative smears triggered suspicion of contamination with environmental mycobacteria, which was confirmed by reexamination of these slides.

A novel method of staining acid-fast bacilli in sputum containers.

Background & Objectives: Making centrifuged deposit smears from sputum to detect acid-fast bacilli (AFB) is considered hazardous. We carried out this study to stain the centrifuged deposits with carbol-fuchsin in sputum containers and to decolourize and counterstain their smears made on glass slides.

Methods: The centrifuged deposits of 180 sputum samples from pulmonary tuberculosis patients were used for making smears (initial deposit smears) and staining by Ziehl-Neelsen (ZN) method for the detection of AFB.

Application of lot sampling of sputum AFB smears for the assessment of microscopy centres.

Setting: Designated microscopy centres (DMC) and additional microscopy centres (AMC) performing sputum acid-fast bacilli (AFB) microscopy, the District TB Centre (DTC) and a reference laboratory (RL).

Objectives: To ascertain the feasibility of adopting lot sampling of AFB smears and to assess the performance of MCs employing Senior Tuberculosis Laboratory Supervisors (STLS) with no knowledge about the principles of quality assurance of AFB microscopy and RL-based laboratory technicians with training on quality assurance for blinded checking of AFB smears.

Methods: Slides from MCs were transported to the DTC and the RL; 20 smears per month per MC were selected systematically; 1547 slides from DMCs and 726 from AMCs were checked, respectively, by STLSs at the DTC and by RL laboratory technicians.

Storage of heat-fixed unstained sputum AFB smears for panel testing in a tuberculosis unit in South India.

To evaluate the suitability for panel testing of heat-fixed unstained sputum AFB smears stored for up to 10 months, panels of slides were prepared at the national laboratory and stored under ambient conditions. Every month, three slides were utilised for panel testing in each of 12 microscopy centres; 70 smears were checked in a blinded fashion after 10 months. Reading errors occurred in 15/360 slides used in panel testing and in 4/70 slides used in blinded checking.

Lot quality assurance sampling of sputum acid-fast bacillus smears for assessing sputum smear microscopy centers.

Assessment of 12 microscopy centers in a tuberculosis unit by blinded checking of eight sputum smears selected by using a lot quality assurance sampling (LQAS) method and by unblinded checking of all positive and five negative slides, among the slides examined in a month in a microscopy centre, revealed that the LQAS method can be implemented in the field to monitor the performance of acid-fast bacillus microscopy centers in national tuberculosis control programs.