SN7 SHORT NOTE 5M

Describe quality assurance and accreditation in the microbiology laboratory.

Microbiology · 2nd Professional — Para-Clinical

Quality Assurance

Quality assurance is the total programme ensuring that laboratory results are reliable, reproducible and clinically useful. It covers everything from the request to the interpretation, not merely the analysis.

Phase	Content and where errors arise
Pre-analytical	Test selection, request form, patient and specimen identification, collection technique, container, transport and storage. The source OF most laboratory errors — commonly quoted as 60 to 70% — and largely outside the laboratory's direct control, which is why it is the phase most often neglected and most worth improving
Analytical	Media, reagents, equipment, method, staff competence, and internal and external quality control. The phase that receives most attention and contributes perhaps 10 to 15% of errors
Post-analytical	Result entry, turnaround time, reporting, critical-value communication, and interpretation by the clinician. A correct result reported late, to the wrong patient, or misunderstood has failed just as completely

Internal quality control (IQC) — performed by the laboratory on its own work, continuously: reference strains (ATCC 25922 E. Coli, ATCC 25923 S. Aureus, ATCC 27853 Pseudomonas) tested with each new batch of media, discs and reagents; sterility and performance checks on every media batch; autoclave monitoring with chemical indicators (Bowie-Dick tape) and biological indicators (Geobacillus stearothermophilus spores for steam, Bacillus atrophaeus for hot air and ethylene oxide); temperature logs for incubators, refrigerators and water baths; equipment calibration and maintenance; and stain performance checks
External quality assessment (EQA) or proficiency testing — blinded specimens sent by an external agency at intervals, processed as routine specimens and the results compared with the peer group. It detects systematic errors the laboratory cannot see in itself, which is precisely what internal control cannot do. In India, schemes are run by AIIMS, CMC Vellore and other centres
The essential discipline is that EQA specimens are handled exactly like routine ones — treating them specially defeats the entire purpose and is a recognised temptation
Documentation — standard operating procedures for every procedure, records of training and competency, equipment logs, and corrective and preventive action records for every non-conformity

CLINICAL PEARL

Most laboratory errors happen before the specimen reaches the laboratory. The pre-analytical phase — a mislabelled bottle, a swab instead of pus, a delayed transport, a request form marked only "C/S" — accounts for the large majority, and no amount of analytical rigour can compensate. This means the greatest gains in laboratory quality come from training clinical and nursing staff, not from buying instruments; and it makes specimen quality a clinical responsibility rather than a laboratory complaint.

Accreditation and Laboratory Indicators

NABL (National Accreditation Board for Testing and Calibration Laboratories) accredits Indian laboratories against iso 15189, the international standard for medical laboratories, covering both management and technical requirements. NABH accredits hospitals and includes laboratory standards
Accreditation requires documented procedures, competent and trained staff, calibrated equipment, participation in EQA, internal audit, management review, complaint handling, and a system of continual improvement
Useful quality indicators — specimen rejection rate; blood culture contamination rate (which should be under 3% and directly reflects collection technique); turnaround time for critical results; the proportion of positive cultures; EQA performance; the rate of repeat requests; and critical-value communication compliance
The laboratory's clinical role — producing and circulating an annual cumulative antibiogram, advising on antibiotic policy, participating in infection control and stewardship, telephoning critical results, and being available for consultation. A microbiology laboratory that only issues reports is working at a fraction of its usefulness

Applied Aspects

The clinician controls the pre-analytical phase, which is where most errors occur; labelling the specimen correctly, sending the right material before antibiotics, and writing the clinical details are the highest-value quality interventions available
Treat a rejection as information rather than obstruction; the laboratory is preventing a misleading report from entering the patient's record
Monitor the blood culture contamination rate as a ward-level quality measure; it is easily calculated, directly actionable, and each false positive costs unnecessary antibiotics and additional hospital days
Use the local antibiogram when writing or following an empirical antibiotic policy; it is the laboratory's most valuable single output and is frequently produced and then ignored
Participate in EQA honestly; a laboratory that handles proficiency specimens specially learns nothing and continues to make the same errors on patients
Accreditation is a means, not an end — its value lies in the documented processes and the habit of audit it enforces, and a laboratory can hold a certificate while failing patients if the culture behind it is one of compliance rather than of improvement
Internal control cannot detect a systematic error, because the laboratory is checking its own method against its own expectations; only external assessment reveals a consistent bias
Turnaround time is part of quality; a correct result issued after the clinical decision has been made has failed the patient as surely as a wrong one
Telephone critical results and record that it was done; a positive blood culture or cerebrospinal fluid Gram stain sitting in a report queue is a patient safety incident

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