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Presentation Summary

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Quality Assurance in Diagnostic Microbiology Laboratory

Based on: Ananthanarayan & Paniker | Bailey & Scott | Koneman's Color Atlas | CLSI Standards

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SECTION 1: INTRODUCTION & FOUNDATIONS

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Slide 1 — Title Slide

• Principles and Practice
• Sources: Ananthanarayan & Paniker's Textbook of Microbiology | Bailey & Scott's Diagnostic Microbiology | Koneman's Color Atlas and Textbook of Diagnostic Microbiology | CLSI Standards

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Slide 2 — What Is Quality Assurance?

Quality Assurance (QA): "An all-encompassing program that guarantees the quality of laboratory test results through careful control of all the variables that can affect the accuracy and precision of test results."

QA is: "A program designed to ensure that results issued by the laboratory are correct and that the laboratory functions in an efficient and cost-effective manner."

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Slide 3 — Total Quality Management (TQM) in Microbiology

• QA = umbrella management system
• QC = subset — monitoring test performance
• Continuous Quality Improvement (CQI) = ongoing refinement
• Three pillars:
  1. Structure — physical lab, equipment, personnel
  2. Process — specimen handling, testing methods, reporting
  3. Outcome — accuracy of results, patient outcomes, TAT

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Slide 4 — The Three Phases: Total Testing Process

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Slide 5 — The Microbiology Lab and Infectious Disease Diagnosis

• Isolation and identification of causative microorganisms
• Antimicrobial susceptibility testing
• Serological diagnosis (antibody/antigen detection)
• Molecular diagnosis (NAATs)
• Epidemiological surveillance and outbreak investigation

"The diagnosis of an infectious disease depends on the isolation and identification of the causative organism or the detection of specific antibodies in the patient's serum." — Ananthanarayan & Paniker

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Slide 6 — Regulatory & Accreditation Framework

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SECTION 2: PRE-ANALYTICAL QA

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Slide 7 — Pre-Analytical Phase: Overview

• A contaminated or improperly collected specimen yields misleading results
• No amount of technical excellence in the lab can compensate for a poor specimen

"The single most important step in the recovery of microorganisms from clinical specimens is the proper collection of the specimen." — Bailey & Scott's Diagnostic Microbiology

• Test request / clinical information
• Patient preparation
• Specimen collection technique
• Labeling and identification
• Transport and storage
• Receipt and processing

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Slide 8 — Specimen Request and Clinical Information

• Patient name and date of birth / hospital ID
• Type of specimen and anatomical site
• Date and time of collection
• Name of ordering physician and contact
• Clinical diagnosis / relevant history
• Current antimicrobial therapy (affects culture sensitivity)
• Type of test requested

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Slide 9 — Specimen Collection: General Principles

1. Collect from the actual site of infection — not adjacent normal flora
2. Collect during acute phase of illness
3. Collect adequate quantity
4. Collect before starting antimicrobials whenever possible
5. Use appropriate sterile technique to avoid contamination
6. Use correct collection devices (swabs, aspirates, tissue)
7. Use appropriate transport media immediately after collection
8. Label clearly and transport promptly

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Slide 10 — Site-Specific Collection Requirements

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Slide 11 — Blood Culture Collection: QA Specifics

• Number: 2–3 sets per episode (increases sensitivity to >95%)
• Volume: 8–10 mL per bottle in adults; 1–3 mL pediatric
• Timing: Before antibiotics; within 30–60 min of each other during acute fever
• Antisepsis: 70% isopropanol → 2% chlorhexidine or tincture of iodine — allow to dry
• QA indicator: Blood culture contamination rate — target <3% (CAP/CLSI benchmark)
• Common contaminants: Coagulase-negative Staphylococci, Bacillus, Corynebacterium, Propionibacterium

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Slide 12 — Sputum Quality Criteria: Bartlett Scoring

• Gram stain screen is mandatory before culture
• Murray-Washington / Bartlett grading:

"A predominance of squamous epithelial cells indicates oropharyngeal contamination, and the specimen should be rejected." — Bailey & Scott

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Slide 13 — Transport Media and Systems

• Prevent desiccation
• Maintain pH
• Inhibit overgrowth of normal flora
• Preserve viability of fastidious organisms

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Slide 14 — Time-Temperature Requirements for Transport

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Slide 15 — Specimen Rejection Criteria

• Unlabeled or mismatched label/requisition
• Container leaking, broken, or grossly contaminated
• Incorrect fixative (e.g., formalin for culture)
• 24-hour urine for culture
• Multiple swabs when one was required

• Sputum with >25 squamous epithelial cells/lpf
• Duplicate wound cultures within 24 h
• Rectal swab (if stool possible)
• Prolonged transport time or wrong temperature

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SECTION 3: CULTURE MEDIA QUALITY CONTROL

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Slide 16 — Culture Media in Diagnostic Microbiology

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Slide 17 — CLSI M22: QC of Culture Media

1. Visual inspection: Color, turbidity, hemolysis, contamination, cracks, moisture
2. pH verification: Acceptable range ±0.2 pH units of stated value
3. Sterility check: Incubate uninoculated plates/tubes at 35°C × 24–48 h — no growth
4. Growth promotion (positive control): Inoculate with ATCC reference strain — adequate growth expected
5. Selectivity (negative control): Inoculate with organism that should be inhibited — no/limited growth expected
6. Biochemical reactivity: Correct biochemical reactions observed

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Slide 18 — QC Organisms for Common Media

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Slide 19 — Media Storage and Shelf Life

• Refrigerated media (2–8°C): Most agar plates, prepared broths
• Room temperature: Thioglycollate broth (do not refrigerate)
• Protect from light (especially chocolate agar, thio broth)
• Shelf life:
  • Commercially prepared plates: Follow manufacturer expiry
  • In-house prepared: Typically 2 weeks refrigerated
  • Dehydrated media (powder): 2–5 years in sealed containers at room temp
• Never use expired media — document lot number and expiry for every batch

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Slide 20 — Preparation of In-House Media: QA Checks

1. Weigh dehydrated medium accurately (record batch weight)
2. Dissolve in measured volume of distilled water
3. Check/adjust pH (before autoclaving for most; after for blood-containing)
4. Autoclave at 121°C, 15 psi, 15 minutes (record autoclave run)
5. Cool to 50–55°C before adding blood/supplements
6. Pour into sterile plates/tubes under sterile conditions
7. QC: Visual inspection + pH + sterility + growth promotion before use
8. Label: Medium name, lot, date prepared, expiry, technologist initials

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SECTION 4: STAINING QUALITY CONTROL

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Slide 21 — Gram Stain QC

• Run positive and negative controls with each batch of staining
• QC organisms (on same slide or separate):
  • Staphylococcus aureus → gram-positive cocci (purple)
  • Escherichia coli → gram-negative rods (red/pink)

"A good Gram stain distinguishes bacterial morphology and gram reaction and is directly correlated with culture results." — Koneman

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Slide 22 — Other Stain QC

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SECTION 5: ANTIMICROBIAL SUSCEPTIBILITY TESTING (AST) QC

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Slide 23 — AST Methods and Standards

"The disk diffusion method, as described by Bauer, Kirby, Sherris, and Turck, remains the most widely used test for determining antimicrobial susceptibility." — Koneman

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Slide 24 — Kirby-Bauer Disk Diffusion: QC

• Mueller-Hinton agar:
  • Depth: 4 mm ± 0.5 mm
  • pH: 7.2–7.4
  • Free of thymidine (interferes with sulfonamides/trimethoprim)
  • Divalent cations (Ca²⁺, Mg²⁺) within range
• Inoculum: 0.5 McFarland standard (1–2 × 10⁸ CFU/mL)
• Disk potency: Store at -20°C (carbapenem, clavulanate-containing); 4°C for others
• Incubation: 35–37°C, 16–18 h; 24 h for staphylococci/oxacillin/vancomycin

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Slide 25 — AST QC Organisms and Acceptable Ranges

• QC must be performed each day of testing (or weekly if QC criteria met per CLSI M02)
• Results plotted on Levey-Jennings chart to detect trends

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Slide 26 — AST Interpretation: Breakpoints and Reporting

• S (Susceptible): Infection likely to respond to standard dosing
• I (Intermediate): Uncertain — may respond to higher dose or concentrated site
• R (Resistant): Unlikely to respond to standard therapy
• SDD (Susceptible-Dose Dependent): Response dependent on achieving high drug levels

• Use cascade/selective reporting to promote antibiotic stewardship
• Report ESBL, carbapenemase, MRSA flags prominently
• Confirm by additional testing when resistance is unexpected (e.g., vancomycin-resistant S. aureus)

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SECTION 6: INTERNAL QUALITY CONTROL (IQC)

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Slide 27 — Principles of IQC

• Day-to-day reproducibility of test results
• Instrument performance and reagent consistency
• Technologist technique

"Controls should be treated exactly as patient specimens — same preparation, same technologist, same instrument." — Koneman

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Slide 28 — Levey-Jennings Charts and Westgard Rules

• Plot control values (Y-axis) vs. time/run (X-axis)
• Draw lines at mean ± 1SD, ±2SD, ±3SD
• Visual identification of random vs systematic error

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Slide 29 — Out-of-Control: Response Protocol

1. Stop: Do NOT report patient results from that run
2. Check controls: Wrong concentration? Degraded? Wrong storage?
3. Check reagents: Expired? New lot? Stored correctly?
4. Check equipment: Temperature? Pipettes calibrated? Correct incubation?
5. Check technique: New analyst? Procedural deviation?
6. Check for contamination: Environmental contamination?
7. Repeat QC with fresh controls
8. If QC passes → release results; document findings and corrective action
9. If repeated failure → escalate to supervisor/director; hold patient results
10. Root cause analysis and corrective action plan documented

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SECTION 7: EXTERNAL QUALITY ASSESSMENT (EQA)

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Slide 30 — EQA / Proficiency Testing: Principles

External Quality Assessment (EQA) / Proficiency Testing (PT): "A system for objectively checking laboratory performance by means of interlaboratory comparisons, using external samples of known composition."

• Independent validation that the lab's methods are working correctly
• Identifies bias, systematic errors, or performance gaps
• Required for laboratory accreditation (NABL, CAP, ISO 15189, CLIA)
• Benchmarks the lab against peer institutions nationally/internationally

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Slide 31 — EQA in Practice

1. External body (CAP, EQAS, RCPAQAP, UK NEQAS, national programs) sends unknown samples
2. Lab processes them exactly as patient specimens — same methods, same personnel
3. Results submitted to provider
4. Performance compared against target value and peer group
5. Report returned: graded acceptable / unacceptable

• Bacteriology: Organism identification + AST
• Mycobacteriology: Smear microscopy + culture identification
• Mycology: Yeast/mould identification
• Parasitology: Stool examination, smear reading
• Serology: Antibody titers
• Molecular: NAAT detection / quantification

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Slide 32 — Managing EQA Failures

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SECTION 8: EQUIPMENT QC AND MAINTENANCE

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Slide 33 — Laboratory Equipment: QC Requirements

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Slide 34 — Autoclave QC: Sterilization Assurance

1. Physical indicators: Built-in gauges (temperature, pressure, time) — recorded each run
2. Chemical indicators (CI):
   • Bowie-Dick test strips: Color change confirms steam penetration
   • Class 5/6 integrating indicators inside packs
3. Biological indicators (BI):
   • Geobacillus stearothermophilus spore strips
   • Most resistant to moist heat (121°C)
   • Run weekly or per load for critical cycles
   • No growth after incubation = sterilization confirmed

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Slide 35 — Biosafety Cabinet (BSC) QC

• Annual certification by qualified engineer (NSF/ANSI 49)
• Before each use: Check airflow alarm, UV light (if fitted), wipe-down with 70% alcohol
• HEPA filter replacement: Per manufacturer schedule or when airflow compromised
• Decontamination before servicing: Formaldehyde or vaporized hydrogen peroxide

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SECTION 9: PERSONNEL AND COMPETENCY

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Slide 36 — Personnel Requirements

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Slide 37 — Competency Assessment

1. Direct observation of specimen processing and testing
2. Monitoring of recording and reporting of results
3. Review of QC records and PT results
4. Direct observation of equipment maintenance
5. Assessment of problem-solving skills (e.g., evaluate written unknowns)
6. Testing of previously analyzed samples / EQA specimens

• Initial: After completion of training (before independent testing)
• 6-month reassessment: During first year
• Annual: Every year thereafter

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Slide 38 — Training in the Microbiology Laboratory

• Standard Operating Procedures (SOPs) for all tests performed
• Specimen handling, collection, and rejection criteria
• Gram staining technique and interpretation
• Culture reading, colonial morphology, preliminary identification
• AST performance and interpretation (Kirby-Bauer, MIC)
• QC procedures and documentation
• Biosafety (BSL-2 practices, PPE, spill management)
• Bloodborne pathogen training (OSHA standard)
• Fire safety, chemical hygiene, emergency procedures
• LIS operation and result entry/verification

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SECTION 10: SAFETY QA IN MICROBIOLOGY

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Slide 39 — Biosafety Levels

"Most clinical specimens should be handled using Universal (Standard) Precautions as a minimum." — Koneman

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Slide 40 — Standard Precautions and PPE

• Treat ALL specimens as potentially infectious
• Mandatory PPE in microbiology:
  • Gloves: Change between specimens; remove before leaving lab
  • Lab coat: Not worn outside the lab
  • Eye protection/face shield: During specimen processing, centrifugation
  • Mask/respirator: N95 for suspected AFB specimens (BSL-3 practices)
• No: Eating, drinking, mouth pipetting, applying cosmetics in the lab
• Wash hands: After removing gloves, before leaving the lab

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Slide 41 — Exposure Control and Incident Reporting

• Needlestick/sharps injury:
  1. Wash immediately with soap and water
  2. Report to supervisor and occupational health
  3. Baseline serology (HIV, HBV, HCV)
  4. Post-exposure prophylaxis (PEP) if indicated within 2–4 h
• Spill management:
  • Small spill (BSL-2): Cover with paper towel + 10% bleach; 20 min contact; clean up; decontaminate
  • Large spill or BSL-3: Evacuate; notify supervisor; wait for trained decontamination team
• All exposures documented: Date, nature, circumstances, follow-up actions

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SECTION 11: DOCUMENTATION AND LIS

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Slide 42 — SOPs: Structure and Management

• CLSI QMS02: "Quality Management System — Development and Management of Laboratory Documents"
• Required sections in an SOP:
  1. Title, SOP number, version, effective date
  2. Purpose and clinical relevance
  3. Principle of the test
  4. Specimen requirements (type, volume, container, storage)
  5. Equipment and reagents (with lot tracking)
  6. Step-by-step procedure
  7. QC requirements and acceptance criteria
  8. Interpretation of results / reference criteria
  9. Reporting instructions
  10. Limitations and interferences
  11. Safety precautions
  12. References (CLSI, manufacturer IFU)
  13. Authorization signatures (author, reviewer, director)

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Slide 43 — Document Control

• Each SOP has a unique identifier and version number
• Annual review and re-authorization — even if no changes
• Only current version accessible to staff — obsolete versions removed from circulation
• Master list of all SOPs maintained by QA coordinator
• Changes documented with reason, date, and authorized signature
• Controlled copies distributed; uncontrolled copies marked as such
• LIS or electronic document management systems preferred for access control

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Slide 44 — Record Keeping

• Documents: Procedures, policies, forms (written before the fact)
• Records: Evidence that activities were performed (written after the fact)

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Slide 45 — Laboratory Information System (LIS) in QA

• Unique accession number for every specimen (audit trail)
• Patient identification verification (wristband scan / barcode)
• Specimen rejection logging with reason codes
• Automated culture workload and TAT tracking
• AST reporting with cascade/selective reporting logic
• Critical value flagging with call-back documentation
• Trend monitoring and epidemiology reports (antibiograms)
• Interface with blood culture instruments (automated alert on positivity)
• PT/QC data management and charting
• Authorized result release (autoverification with rules)

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SECTION 12: SPECIAL AREAS OF MICROBIOLOGY QA

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Slide 46 — Mycobacteriology QA

• BSL-3 practices for all culture work
• Three sputum specimens: Early morning, on 3 consecutive days
• Smear microscopy QC:
  • Positive control slide with known AFB+ case
  • Negative control slide
  • Two-microscopist reading for discrepant results (WHO recommendation)
• Culture media QC (LJ, MGIT):
  • M. tuberculosis H37Rv ATCC 27294
  • Sterility check of each batch
• Grading smears (WHO / Ananthanarayan):
  • Negative: 0 AFB / 100 fields
  • Scanty: 1–9 AFB / 100 fields (report exact count)
  • 1+: 10–99 AFB / 100 fields
  • 2+: 1–10 AFB / field (>50 fields)
  • 3+: >10 AFB / field (>20 fields)

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Slide 47 — Molecular Microbiology QA

• Zone 1: Master mix preparation (pre-PCR, ultra-clean)
• Zone 2: Specimen extraction and nucleic acid addition
• Zone 3: Amplification and detection (post-PCR)
• Unidirectional workflow only — no backflow

• Accuracy, precision, analytical sensitivity (LOD), specificity, interfering substances

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Slide 48 — Blood Culture System QA

• Instrument maintenance: Daily flag review, quarterly preventive maintenance
• Bottle integrity: Inspect for cracks, leaks, incorrect fill before incubation
• Blood culture contamination rate: Monitor monthly; target <3%
• Positive bottle Gram stain: STAT critical value — call clinician within defined TAT
• Subculture from positive bottles: Blind subculture at 12 h for some systems

1. Prepare Gram stain from positive bottle
2. Call result to physician/nurse (critical value) — document
3. Set up blood agar + chocolate agar + MacConkey subcultures
4. Consider direct sensitivity testing from positive bottle broth

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SECTION 13: QUALITY INDICATORS AND CQI

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Slide 49 — Key Quality Indicators (KQIs) for Microbiology

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Slide 50 — CQI Cycle and Summary

  PLAN  →  Identify problem using KQIs and data
            Set measurable improvement targets
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   DO   →  Implement intervention
            Train staff; modify procedure or workflow
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 CHECK  →  Measure outcome against target
            Re-audit; compare KQIs before/after
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   ACT  →  Standardize if improved
            If not improved → go back to PLAN

1. Specimens: Right patient, right site, right container, right time
2. Media & Reagents: Verified, documented, within expiry
3. Methods: Standardized per CLSI; controlled with ATCC organisms
4. Personnel: Trained, competent, assessed
5. Equipment: Calibrated, maintained, monitored
6. Documentation: Comprehensive, current, retrievable
7. EQA: Regular participation; failure triggers RCA
8. Safety: Biosafety integrated into every procedure
9. CQI: Data-driven, continuous, director-led

"Quality in the microbiology laboratory is not optional — it is the foundation upon which every clinical decision rests."

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References for This Presentation

1. Ananthanarayan R & Paniker CKJ — Textbook of Microbiology, 10th Ed. (Orient Longman)
2. Bailey & Scott — Diagnostic Microbiology, 14th Ed., Forbes BA, Sahm DF, Weissfeld AS (Elsevier Mosby)
3. Koneman EW et al. — Koneman's Color Atlas and Textbook of Diagnostic Microbiology, 7th Ed. (Wolters Kluwer/Lippincott)
4. CLSI M02 — Performance Standards for Antimicrobial Disk Susceptibility Tests
5. CLSI M07 — Methods for Dilution Antimicrobial Susceptibility Tests for Bacteria
6. CLSI M11 — Methods for Antimicrobial Susceptibility Testing of Anaerobic Bacteria
7. CLSI M22 — Quality Assurance for Commercially Prepared Microbiological Culture Media
8. CLSI M29 — Protection of Laboratory Workers from Occupationally Acquired Infections
9. CLSI M40 — Quality Control of Microbiological Transport Systems
10. CLSI M47 — Principles and Procedures for Blood Cultures
11. CLSI M100 — Performance Standards for Antimicrobial Susceptibility Testing (updated annually)
12. CLSI MM01 — Molecular Diagnostic Methods for Infectious Diseases
13. CLSI QMS01, QMS02, QMS03, QMS05, QMS12, QMS24 — Quality Management System series
14. CLSI EP15, EP23 — User verification; risk management in the lab

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