Sterility Testing

VTH Policy # Pharm624

Implementation Date: 11/2021

Date of Last Revision: 6/24/2023

Next Review Due: 6/23/2026


Reviewed by VTH Administrative Team: 11/2021

Reviewed by VTH Board: N/A


Approved by VTH Director: 11/2021

Reviewed by Biosecurity Subcommittee: N/A

Subject to modification by the VTH Director without approval.


The intent of this policy is to explain the procedure for the testing of sterile products that are prepared by the Medication Dispensary. The purpose is to provide the process for performing sterility testing on items prepared in the cleanroom for the purposes of extended beyond-use dating. This policy covers all sterility testing of products prepared in the cleanroom that is being tested for the purpose of a beyond-use date extension. This does NOT cover testing of medications pulled from use.

  • One unit from each batch must be sterility tested to provide maximum beyond-use dating per USP 797. Sterility testing needs to be completed in compliance with USP 71 standards.


  1. 10% of each batch for each repackaged drug will be sent to the VDL for sterility testing
    • Starting 3/12/2021, only one unit per batch needs to be sent unless determined otherwise

  2. Sterility testing will be done in accordance with USP <71>

  3. Results of sterility testing will be sent to

  4. Sterility testing will be charged to the Pharmacy FOP (301732-255060-255006)

  5. When testing controlled substances, a pharmacist will arrange to meet with the VDL technician that completes the testing. This pharmacist will supervise the use of the controlled substances and then bring back any unused drug for wasting in the medication dispensary controlled substance disposal log.

  6. Non-controlled medications can be left with the VDL technician for testing after the pharmacist leaves. These will be disposed of by the VDL technician.

Procedure (if applicable)

  1. When a batch of medication is prepared in the cleanroom, 10% will be calculated on the repackaging log. That number of units will be pulled out randomly for sterility testing. A unit must have at least 0.2 ml of drug.
    • Starting with batches on 3/12/21, only one unit needs to be pulled to be sterility tested unless positive results are returned from any batch. In this case, testing will be returned to 10% or a minimum of four units.
  1. Once weekly, a pharmacist will arrange a meeting with the VDL technician, to submit the samples. The current contact (as of 6/24/23) is Chien-Chi Hung ( For controlled substances, the pharmacist will need to be present while the medication is being aliquoted to ensure any remaining quantity is properly disposed of. For non-controls, they can be left for aliquoting at a later time prior to being disposed of by the VDL technician.

  1. Prior to taking the samples to be tested, a VDL Sample Submission form needs to be completed. The following is the information to provide:

- Veterinarian: Julia Whittington

- FOP: 301732-255060-255006

- Billing Comments: Pharmacy

- Copy Results: and check the ‘other’ box

- Check ‘drop off’

- Specimen: Swab site vial

- Under cultures, check ‘Environmental/C&D’

- History or additional information (pg 2): Pharmacy

- Complete the total number of samples and list one line for each unit being sampled (pg 2)

  1. Number each vial/syringe label with the number corresponding to the line number on the sheet.

  2. Update the microbial testing spreadsheet in the shared drive with the samples being submitted.

  3. VDL technician will perform the sterility testing as follows:
    • Fifty microliters of drug will be directly plated on a Columbia agar containing 5% sheep blood and a Cholate agar plate and incubated under 37ᵒC with 5% CO2 for at least 48 hrs. to screen the growth of bacteria.
    • Fifty microliters of drug will be also inoculated into 10 ml Thioglycolate enrichment broth and inoculated at 37ᵒC incubator for 48 hrs. Growth of bacteria will be determined by checking the turbidity of medium. If the Thioglycolate turns cloudy, 1-5 µl of medium will be plated on Columbia agar containing 5% sheep blood and incubated under 37ᵒC with 5% CO2 for at least 48 hours to confirm the growth of bacteria.
    • If any bacterial colonies were noticed on the culture plates, they will be further identified using MALDITOF, and a quantitative result shown as CFU/ml may be provided by VDL to indicate bacterial numbers presenting in the drug.
  1. The pharmacist will return any unused controlled substances to the medication dispensary for appropriate wasting in the controlled substance disposal log.

  2. When the preliminary results are received, the microbial testing spreadsheet will be updated to reflect the results. When the final results are received, the spreadsheet will be updated with any changes.

  3. If a sample is positive, the entire lot will need to be recalled and wasted as contaminated.

  4. Once final sterility testing results have been received, if the results are positive, cross out the batch, initial, and write the date that the entire lot was wasted. Nothing needs to be done if the batch was negative.

  5. If three positive results are received in a row, processes and procedures should be reassessed to ensure that a sterile environment is being maintained during repackaging.


  • USP : United States Pharmacopeia
  • VDL : Veterinary Diagnostic Lab
  • FOP : Payment account that is being charged out (e.g., Pharmacy, Hospital, etc.)

Definitions (if applicable)

Veterinary Teaching Hospital (VTH): The collective clinical services of the Large Animal Clinic, Midwest Equine, the Small Animal Clinic, and the Veterinary Medicine South Clinic.


KeywordsPharmacy, dispensary, BUD, Beyond use, sterile, sterility, test, cleanroom, dating, batch, compliance, UPS, 797, 800, VDL, sample, unit, swab, incubator, bacteria, growth, cloudy, plate, culture, agar, aliquot, microbial, positive, negative, environment, repackage   Doc ID124645
OwnerJenny C.GroupUofI College of Veterinary Medicine Teaching Hospital
Created2023-03-07 13:48 CSTUpdated2023-07-03 15:45 CST
SitesUniversity of Illinois College of Veterinary Medicine Teaching Hospital
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