Process Control: Quality in Microbiology

Process Control: Quality Control of Qualitative and Semi-Quantitative Procedures

• Learning Objectives: Participants should be able to differentiate between built-in and traditional controls, describe using stock cultures for microbiology QC, discuss quality control procedures for stains in microscopic examinations, and describe methods for verifying microbiological media performance.

• Scenario: A laboratory identifies Pseudomonas aeruginosa. What quality control (QC) measures can be used to confirm the isolate's correct identification?

• The Quality Management System: This system involves various interconnected components: Organization, Personnel, Equipment, Purchasing & Inventory, Process Control, Information Management, Documents & Records, Occurrence Management, Assessment, Process Improvement, Customer Service, and Facilities & Safety.

Qualitative or Semi-Quantitative Tests

• Examples: Microscopic examinations, dipsticks, serologic procedures, microbiological procedures, and any reaction producing non-numeric results.

Important Concepts

• Sample Management: Managing samples correctly is important.
• Staff Competency: Staff must possess the necessary skills.
• Equipment Maintenance: Equipment should be maintained properly.
• Control Materials: Utilizing control materials is crucial.
• Stains, Media, and Reagents Management: Effective management of stains, media, and reagents is needed.
• Record Keeping: Maintaining appropriate records is vital.

Quality Control Materials

• Built-in Controls: Integrated into the design of a test kit, assess certain aspects of kit performance, may not assess the entire testing process.
• Control Materials: Mimic patient samples.
• Reference Organisms: Crucial for validation.

Built-in Controls

• Integrated into the design of a test kit.
• Automatically run with each test performed.
• Assess certain aspects of kit performance.
• May not assess the entire testing process.

Traditional Controls

• Materials with known reactivity.
• Mimic patient samples.
• Assess the integrity of the entire test system.

Using Traditional Controls

• Test as per patient samples.
• Use a positive and negative control.
• Include a weak positive control for immunological procedures.
• Choose positive controls close to the cut-off value.
• Include control to monitor the extraction phase.

Stock Cultures for QC

• Reference strains
• In-house developed strains
• Predictable reactions in stains and media
• Ensures media, reagents, and supplies work as intended.

Sources for Obtaining Reference Strains

• ATCC (American Type Culture Collection)
• NTCC (National Type Culture Collection, UK)
• CIP (Pasteur Institute Collection, France)

Stains

• Stains are important and require careful management.
• Stains should be examined for contaminants (bacteria and fungi). Examination should be conducted with known organisms (for example, cells and organisms) to check for precipitation and crystal shards, if applicable.

Stain Management

• Use established procedures for preparation or reconstitution.
• Label clearly with content, concentration, date prepared, placed in service, expiration, and initials.
• Store appropriately.

Quality Control for Stains

• Check with known organisms or cells.
• Examine for crystal shards or precipitation.
• Examine for contaminants (bacteria and fungi).

Gram Stain (Example)

• Visual quality control comparison: Good quality vs. Poor quality depictions.

QC of Microbiology Media

• Verify performance of all in-house prepared media and new commercially prepared lots only.

Media Problems to Avoid

• Outdated media
• Dried-out media
• Contaminated media
• Human blood should not be used for media preparation because of batch-to-batch variability, potential inhibitory substances including antimicrobials, and possible biohazards.

Quality Control of Growth Media

• Keep records of in-house prepared media.
• Record outcomes in a dedicated media logbook: pH, sterility, ability to support growth, response of stock cultures, biochemical frequency, and test each new batch or lot number.

Summary

• Qualitative tests produce non-numerical results.
• Semi-quantitative tests provide estimates.
• Establish a quality control program for qualitative and semi-quantitative tests.

Key Messages

• QC procedures must be followed by all staff.
• Always record QC results and corrective actions.
• If QC results are not acceptable, do not report patient results.

Test your knowledge on quality control measures in microbiology labs, focusing on qualitative and semi-quantitative procedures. Participants will learn to differentiate control types, utilize stock cultures, and discuss methods for verifying microbiological media performance. This quiz will enhance your understanding of essential quality management systems within laboratory settings.