LT-Microscopy & NAAT

• Standard precautions are a group of infection control practices to reduce the risk of transmission of pathogens.
• These are based on the principle that all blood, body fluids, secretions, excretions except sweat, non-intact skin, and mucous membranes may contain
  transmissible infectious agents.
• Standard precautions are applicable to all patients in all healthcare settings and combine the major features of universal precautions, body substance isolation, and airborne precautions.

Infection prevention and control (IPC) practices are important in maintaining a safe environment for everyone by reducing the risk of the potential spread of disease.

IPC is a practical, evidence-based approach which prevents patients and health workers from being harmed by avoidable infection. It is relevant to health workers and patients at every single health-care encounter.

Random Blinded Rechecking (RBRC) is the process of re-reading a statistically valid sample of routine slides from a designated microscopy centre (DMC) based on lot quality assurance strategy (LQAS) in a blinded manner to assess the laboratory performance.

RBRC Process

Annual slide sample and the monthly sample for Random Blinded Rechecking (RBRC) is determined by the District TB Officer (DTO), assisted by the Intermediate Reference Laboratory (IRL), Statistical Assistant (SA) or Data Entry Operator (DEO) based on Lot Quality Assurance Sampling (LQAS) method.

Under the LQAS method, sample size depends on 3 components:

1. Annual Negative Slide Volume (ANSV)
2. Slide Positivity Rate (SPR)
3. Sensitivity of picking up lower bacili count in microscopy

Process of RBRC (Figure 1)

Random Blinded Rechecking (RBRC) is an External Quality Assurance (EQA) method that provides reliable assurance that a district has an efficient Acid-fast Bacillus (AFB) microscopy laboratory network to support National TB Elimination Programme (NTEP) (Figure).

Blinded rechecking is a process of re-reading a statistically valid sample of slides from a laboratory to assess whether that laboratory has an acceptable level of performance.

Documentation of any significant problems (technical, operational, others) and feedback for corrective action during On-site Evaluation (OSE) is necessary to formulate plans with the District TB Officer (DTO), Senior TB Laboratory Supervisor (STLS), Medical Officer (MO), Intermediate Reference Laboratory (IRL), National Reference Laboratory (NRL) and Laboratory Technician (LT) to improve the quality of smear microscopy.

Checklists for OSE

A field visit is an ideal way to obtain a realistic assessment of the conditions and skills practiced in the laboratory. Under National TB Elimination Programme (NTEP), On-site Evaluation (OSE) of Intermediate Reference Laboratories (IRLs) and District TB Centres (DTCs)/ Designated Microscopy Centres (DMCs) is therefore an essential component of a meaningful Quality Assurance (QA) programme.

Panel testing is a method of External Quality Assurance (EQA) that is used to determine the adequacy of a laboratory technician to perform Acid-fast Bacillus (AFB) smear microscopy. This method evaluates individual performance in staining and reading and not the other laboratory activities.

Quality Assurance (QA) is a systematic process used to determine the quality standards of TB laboratories.

Poor quality diagnosis may results in failure to diagnose TB or unnecessary treatment of non-TB case. Thus an effective QA mechanism is important for reliability of laboratory diagnosis.

QA in National Tuberculosis Elimination Programme (NTEP) consists of:

The administrative measures at a health care facility play an important role in preventing the spread of TB in health care settings. It includes Administrative controls for outpatient and inpatient settings

Administrative measures at Outpatient(OPD) settings
1. Screen for respiratory symptoms as early as possible upon patient’s arrival at the health care facility thereby reducing the overall stay of such patients in the healthcare facility