SOP on Out of Specification (OOS) Results in Microbiology Laboratory

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SOP on Out of Specification (OOS) Results in Microbiology Laboratory

1.0 Objective

To establish a systematic procedure for reporting, investigation, evaluation, and disposition of Out of Specification (OOS) results generated in the Microbiology Laboratory.

2.0 Scope

2.1 This SOP is applicable to OOS results arising from:

  • Microbial Limit Test (MLT)
  • Sterility Testing
  • Bacterial Endotoxin Test (BET)
  • Environmental Monitoring
  • Water Testing (Potable Water, Purified Water, WFI)
  • Compressed Gas / Compressed Air Monitoring

This SOP applies to the Microbiology Section of the Formulation Plant.

3.0 Responsibility

3.1 Head – Microbiology

  • Initiate and conduct OOS investigation
  • Ensure documentation and scientific evaluation

3.2 Head – Quality Control

  • Review investigation
  • Ensure material/batch status control

4.0 Accountability

4.1 Head – Quality Assurance

  • Final review and approval of OOS investigation
  • Approval of batch disposition decision

5.0 Procedure

5.1 General Procedure for OOS (MLT / Sterility / BET / Environmental Monitoring)

5.1.1 Any OOS result observed during microbiological testing shall be immediately reported to the Head – Quality Control.

5.1.2 The concerned material or batch shall be placed under HOLD status.

5.1.3 Investigation shall be carried out as per the approved checklist (Annexure – Investigation of OOS Microbiological Test Results).

5.1.4 Investigation shall determine whether:

  • Laboratory error is involved, or
  • The failure is genuine and process-related.

5.2 Environmental Monitoring OOS

5.2.1 Alert Limit Exceedance

  • Immediately inform Head – QC and concerned department.
  • Initiate cleaning and sanitization of affected area.
  • Inspect for visible abnormalities such as leakage, rusting, breakage, etc.
  • Review environmental conditions (Temperature, RH, Differential Pressure).
  • Document findings.

5.3 Action Limit Exceedance

If results exceed Action Limit:

5.3.1 Immediately inform Head – QC and concerned department.

5.3.2 Perform immediate cleaning and sanitization.

5.3.3 Conduct detailed investigation including:

  • Verification of personnel entry and gowning procedure
  • Preservation and identification of microorganism (morphology and Gram character)
  • Review of positive and negative media controls
  • Review of autoclave cycle and sterilization records
  • Review of differential pressure and humidity
  • Review of non-viable particle count (if applicable)
  • Assessment of personnel hygiene

5.3.4 If no assignable cause is found, instruct concerned department to check HEPA filter integrity.

5.3.5 Assess impact on:

  • Batches manufactured on the same day
  • Previous and subsequent batches

Batch disposition shall be decided based on investigation outcome.

5.4 OOS in Water Testing

5.4.1 Immediately inform Head – QC and concerned department.

5.4.2 Initiate cleaning and sanitization of affected system.

5.4.3 Review:

  • Media controls
  • Autoclave cycle records
  • Comparative results from other user points

5.4.4 If a single user point shows OOS:

  • Inspect for leakage, rusting, or breakage
  • Inform Engineering/Production for sanitization

5.4.5 If all user points show OOS:

  • Sanitize entire water system

5.4.6 Perform:

  • Cleaning and sanitization of storage tank (Potable Water)
  • Cleaning and sanitization of storage tank and distribution loop (WFI)

5.4.7 Hold all batches manufactured:

  • On the day of sampling
  • From date of sampling until retest results are available

5.4.8 Perform repeat microbial limit testing with same sample quantity.

5.4.9 Batch Disposition:

  • If retest complies → Batch may be released
  • If retest fails → Batch shall be rejected

5.5 OOS in Compressed Gas / Compressed Air Monitoring

5.5.1 Follow procedure as per Environmental Monitoring OOS.

5.5.2 Repeat sampling with same volume from same location.

5.5.3 Hold all batches manufactured from date of sampling until repeat results are available.

5.5.4 Test batches manufactured using affected compressed gas/air.

5.5.5 If repeat test complies → Batch may be released.

5.5.6 If repeat test fails with same type of organism → Batch shall be rejected.

5.6 OOS in Microbial Limit Test (MLT)

5.6.1 Immediately inform Head – QC and place batch under HOLD.

5.6.2 Review:

  • Positive and negative media controls
  • Autoclave records
  • Environmental conditions
  • Differential pressure and humidity
  • Water quality of the day

5.6.3 Repeat test using:

  • Fresh 25 g sample
  • Different qualified microbiologist

5.6.4 Batch Disposition:

  • If repeat test complies → Batch may be released
  • If repeat test fails with similar organism → Batch shall be rejected

5.7 OOS in Sterility Testing (False Positive Evaluation)

5.7.1 Immediately inform Section Head and place batch under HOLD.

5.7.2 Perform preliminary assessment before retesting.

5.7.3 Retain original test preparations if available.

5.7.4 Conduct detailed laboratory investigation including:

  • Discussion with analyst regarding procedure
  • Review of surface decontamination of LAF
  • Verification of rinse fluid preparation
  • Review of material transfer procedure
  • Review of cleaning and sanitization of testing area
  • Review of media controls
  • Review of autoclave records
  • Review of environmental monitoring data
  • Verification of proper closure of sample containers

5.7.5 Identify flora from:

  • Finger-dab plates of analyst
  • Exposed plates under LAF
  • Personnel involved in filling and plugging
  • Exposed plates in sterile filling area

Preserve plates for comparison.

5.7.6 If laboratory error is confirmed:

  • Retrain analyst
  • Document corrective action

5.7.7 Retest:

  • Conduct repeat sterility test
  • Use double number of samples
  • Performed by different microbiologist

5.7.8 Batch Disposition:

  • If repeat test passes → Batch may be released
  • If repeat test fails and organism matches environmental/personnel flora → Batch shall be rejected

5.8 OOS in Bacterial Endotoxin Test (BET)

5.8.1 Conduct detailed investigation as per approved BET OOS checklist including:

  • Review of negative controls
  • Review of Positive Product Control (PPC)
  • Verification of lysate sensitivity
  • Review of reagent validity
  • Review of depyrogenation records
  • Verification of equipment calibration

5.8.2 Retesting and batch disposition shall be based on investigation findings and QA approval.

6.0 Annexure

  1. Investigation of Out of Specification (OOS) Microbiological Test Results – Checklist

SOP For Handling of Microbiological Data Deviation (MDD) in Microbiology Laboratory

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