applies to all microbial isolates recovered from environmental monitoring activities (surface, air, personnel, and equipment) that are preserved and tested in the Analytical Method Development (AMD) department.

3. Responsibilities

• Microbiologist: Selects, revives, and prepares environmental isolates for challenge testing.
• Validation Analyst: Coordinates the execution of challenge studies using test systems (preserved formulations, disinfectants, surfaces).
• QA Executive: Verifies isolate traceability, study protocols, and documentation.

4. Accountability

The Head of Analytical Method Development is accountable for ensuring that environmental challenge tests are relevant, reproducible, and compliant with regulatory guidelines.

5. Procedure

5.1 Isolate Selection and Traceability

1. Maintain an Environmental Isolate Library (Annexure-1) with:
   • Date and location of isolation
   • Media and incubation condition used
   • Identification (to genus/species if available)
2. Ensure isolates are stored on slants at 2–8°C or in glycerol stocks at -20°C for long-term preservation.

5.2 Revival and Enumeration

1. Revive selected isolates on appropriate agar media.
2. Incubate for 24–72 hours at specified temperatures (based on microbial type).
3. Harvest cells and adjust suspension to ~10⁶ CFU/mL using sterile diluent and 0.5 McFarland standard.

5.3 Challenge Testing Applications

1. Use isolates for:
   • Preservative efficacy testing of drug products
   • Disinfectant validation (contact time vs. log reduction)
   • Cleaning validation surface recovery studies
2. Inoculate test matrices (media, surfaces, coupons) with 10⁴–10⁶ CFU as per protocol.
3. Incubate and quantify microbial recovery post-treatment using suitable media and neutralizers.

5.4 Acceptance Criteria

1. Preservative Challenge: Must meet pharmacopoeial log reduction criteria.
2. Disinfectant Efficacy: Minimum 3-log reduction for vegetative cells and 2-log for fungal spores.
3. Cleaning Validation: ≥70% recovery on clean surfaces with validated swabbing/rinse technique.

5.5 Documentation

1. Record isolate usage and revival logs in Annexure-2.
2. Record recovery data in Annexure-3 with raw count, treatment condition, and reduction log.
3. Summarize findings in final challenge study report approved by QA.

6. Abbreviations

• SOP: Standard Operating Procedure
• CFU: Colony Forming Units
• QA: Quality Assurance

7. Documents

1. Environmental Isolate Master Log – Annexure-1
2. Isolate Revival and Usage Record – Annexure-2
3. Challenge Test Recovery and Log Reduction Data – Annexure-3

8. References

• USP <1227> Validation of Microbial Recovery from Pharmacopoeial Articles
• WHO Technical Report Series 961, Annex 6
• Ph. Eur. 5.1.3 and ISO 14698

9. SOP Version

Version: 2.0

10. Approval Section

	Prepared By	Checked By	Approved By
Signature
Date
Name	Rekha Iyer	Ankit Sharma	Sunita Reddy
Designation	Senior Microbiologist	QA Reviewer	Head – AMD
Department	Analytical Method Development	QA	Analytical Method Development

11. Annexures

Annexure-1: Environmental Isolate Master Log

Isolate ID	Date	Source Area	Microbial ID	Storage Condition
EI-23-004	04/04/2025	Grade B Filling Room	Bacillus subtilis	Slant @ 2–8°C

Annexure-2: Isolate Revival and Usage Record

Isolate ID	Date Revived	Used In Study	Analyst
EI-23-004	15/05/2025	Disinfectant Efficacy	Rekha Iyer

Annexure-3: Challenge Test Data Log

Isolate	Control Count (CFU)	Post-Treatment Count	Log Reduction	Status
B. subtilis	5.6 × 105	2.3 × 102	3.38	Pass

Revision History:

Revision Date	Revision No.	Details	Reason	Approved By
21/05/2025	2.0	Expanded to include surface recovery and disinfectant efficacy validation	Annual Review	Sunita Reddy
10/05/2022	1.0	Initial SOP Release	New SOP	QA Head