How Does Microbiology Contribute to Quality Assurance?
Microbial Limit Testing
Tests:
- Total Aerobic Microbial Count (TAMC)
- Total Yeast and Mold Count (TYMC)
- Test for Specified Microorganisms (e.g., E. coli, salmonella spp..)
Acceptance Limits:
As per WHO and USP <61>:
- TAMC: ≤ 10³ CFU/g or mL.
- TYMC: ≤ 10² CFU/g or mL.
- Specified microorganisms: Must be absent (e.g., E. coli, Salmonella spp.).
Sterility Testing
Tests:
- Membrane filtration (for liquid products).
- Direct inoculation (for solid or viscous products).
Microorganisms Tested:
- General sterility testing checks for absence of all viable microorganisms, including Bacillus subtilis, Candida albicans, Aspergillus brasiliensis, etc.
Acceptance Limits:
- No growth in the test samples.
Endotoxin Testing (Bacterial Pyrogens)
Tests:
- Limulus Amoebocyte Lysate (LAL) test.
Microorganisms Tested:
- Escherichia coli (used for endotoxin standards).
Acceptance Limits:
- Varies depending on the product, expressed as Endotoxin Units (EU/mL).
- Example: ≤ 0.5 EU/mL for water for injection (WFI).
Environmental Monitoring
Tests:
- Settle plate method.
- Active air sampling.
- Surface sampling (contact plates or swabs).
Microorganisms Tested:
- Various environmental flora, e.g., Bacillus spp., Cladosporium spp.
Acceptance Limits (as per WHO/GMP):
- Grade A (sterile): Zero CFU/m³ (air), ZERO CFU/plate (surface).
- Grade B: 10 CFU/m³ (air), 5 CFU/plate (surface).
Water Testing
Tests:
- Microbial enumeration test.
- Test for Pseudomonas aeruginosa.
- Test for endotoxins.
Microorganisms Tested:
- Pseudomonas aeruginosa, coliforms, and other Gram-negative bacteria.
Acceptance Limits (WHO):
- Purified Water: ≤ 100 CFU/mL.
- WFI: ≤ 10 CFU/100 mL.
Antimicrobial Effectiveness Testing (AET)
Tests:
- Challenge test: Deliberate inoculation with specific microorganisms.
Microorganisms Used:
- Escherichia coli.
- Staphylococcus aureus.
- Pseudomonas aeruginosa.
- Candida albicans.
- Aspergillus brasiliensis.
Acceptance Limits:
- No increase in microbial counts over the test period; significant reduction within 7 days.
Bioburden Testing
Microorganisms Tested:
- General bioburden includes all viable organisms.
Acceptance Limits:
- Depends on product type and stage in production.
Read also:
- Interview Questions and Answers On Microbiology
- Setting of Alert and Action Limits for Microbial Monitoring
- What is Media Fill? Why It is Necessary?
Resource Person: Bettahar Nadir
