USP 797 Overview

USP 797 Testing and Analysis

USP 797 Background

USP 797 is designed for health care institutions, pharmacies and other related facilities to insure the sterilization of drugs that are used in compounding sterile preparations. The environmental monitoring and the microbial evaluation of staff’s sterile techniques in compounding sterile preparations (CSPs) is critical to patient care. These guidelines were established to create uniformity for field certifiers in order to have consistent and reliable testing for all facilities. All locations of Aerobiology are AIHA accredited and skilled in enumeration and identification of bacteria and fungi in air samples, surface samples, glove-fingertip samples and can assist in developing a microbial monitoring program for compliance with USP 797.

Download USP 797 Chain of Custody
Download USP 797 Test Codes
Download USP 797 Technical Brief
RODAC / Contact Plate Sampling Protocol

The USP 797 Standard

United States Pharmacopeia (USP), Chapter 797, “Pharmaceutical Compounding, Sterile Preparations” specifies the monitoring of microbiological concentrations on surfaces and air for sterile pharmaceutical compounding.

USP 797 is designed for health care institutions, pharmacies and other related facilities to insure the sterilization of drugs that are used in compounding sterile preparations. The environmental monitoring and the microbial evaluation of staff’s sterile techniques in compounding sterile preparations (CSPs) are critical to patient care. This applies to facilities in which CSPs are prepared, stored, and transported. It affects those involved in sterile compounding; physicians, pharmacists, pharmacy technicians and nurses.


USP 797 specifies a written plan and schedule for microbiological monitoring procedures in pharmaceutical cleanrooms. Monitoring locations are selected to test the areas most prone to contamination during compounding. Typically, this would include area sampling in the proximity of Class II biosafety cabinets or barrier isolators (ISO Class 5 containment). The plan needs to specify sampling for the controlled environments of the pharmacy, including the interior of biosafety cabinets and barrier isolators, compounding rooms (ISO Class 7 buffer areas), and anterooms (ISO Class 8 support areas) located outside the buffer area. Each sampling site (air, contact plate, swab or glove fingertip plate) needs to have predetermined alert and action levels as part of the written plan. Any sample result exceeding the action level requires immediate corrective action which may include full-scale cleaning, ventilation, or High Efficiency Particulate Air (HEPA) filter assessment and suspension of drug compounding until retesting verifies compliance.

Equipment and Sampling Media

USP 797 Sampling Equipment

An impactor sampler is required for USP testing. A sampler capable of pulling 1000L or more of air with a sufficient flow rate that will not dry out media is preferred. Typically a SAS sampler works best for this sampling.

Agar plates “full size or Rodac” are used in conjunction with the sampling pumps. Contact plates may be utilized for sampling of surfaces. Swabs may be utilized for sampling in areas that are difficult to reach.

Sampling Plan

A representative of the certifying company should meet with appropriate facility management personnel prior to testing to perform a risk assessment and develop a robust sampling plan. Environmental sampling must also include all areas and ancillary areas where compounding occurs. For example: nursing units, ER, OR, nuclear medicine, clinics, physician office etc.

Sampling Frequency

Testing should be done at a minimum of two times per year. It is recommended to complete viable sampling after initial certification procedures, but prior to recertification procedures to provide an “as found” result that compounding managers can utilize to show compliance for activities performed until the time of testing.

To learn more about USP 797 testing and our related services please request information using the form here or call us at (877) 648-9150. Thank you!

Facility Risk Level

Risk levels must be determined by the pharmacy director or other appropriate facility personnel and is based upon the compounding practices of the facility. The criteria for determining a facility’s risk level is outlined in the current revision of USP .

Sampling for Bacteria & Fungi

Viable Sampling (Air)

Sampling would be done by taking viable air samples with a high volume air sampler collecting a volume of 500L – 1000L or more at a given rate. Media filled strips or agar plates can be utilized when sampling.

Viable Sampling (Surface)

USP 797 Sampling

Sampling would be done by taking surface samples with contact plates or swabs for hard to reach areas. Swabs must contain a neutralizing buffer and must be processed by plate count method to obtain a total microbial count. Contact plates must incorporate neutralizers which are capable of neutralizing the chemicals used for cleaning the USP 797 clean room environment. Media that is supplemented with lecithin and polysorbate 80 offers a wide range of neutralizing capabilities.

Bacterial Media = TSA – Supports a wide range bacteria (incubated at 30C-35C for 48-72 hours)

  • Gram Negative rods
  • Staphylococcus species (aureus, MRSA and others)
  • Bacillus, Micrococcus, Corynebacterium, Streptomyces

Fungal Media – MEA (incubated at 26C – 30C for 5-7 days)

  • Yeasts
  • Molds (Aspergillus, Cladosporium, Fusarium, Penicillium)

Media should be prepared by a known manufacturer that has quality systems in place to assure the media is appropriate for use and within the expiration date as noted on each agar plate. It should be accompanied by a certificate of analysis that documents suitability for USP use and the results of the quality control testing performed. This testing is completed by the manufacturer and is in addition to and prior to the quality control testing performed at the microbiological laboratory. It should be double or triple bagged and irradiated.

Shipping and Transport

  • Samples should be placed in plastic sealed bags and submitted in a cooler with an ice pack and be shipped over night. This will help to protect them during transport.
  • Plates should be transported and stored inverted to minimize condensation in lids.
  • Media received from the lab, that is used or unused, should be stored in a refrigerator at all times. Samples can be held overnight as long as they are refrigerated after collection.
  • Shipping of samples over a weekend is not recommended.
  • Standard overnight shipping is provided free of charge with $150 analytical fee per project.
  • Pre-printed chain-of-custodies will be provided if requested.
  • Digital versions of our chain-of-custody are also available on our website at
  • If your supplies are needed quicker, expedited service is provided at an additional charge.

Environmental Monitoring

Recommended action levels for microbial contamination in air, surface and glove fingertip.

Pass/Fail Criteria

Viable data collected over time is evaluated by appropriate statistical tools and concern levels are determined. Levels set may not significantly deviate from the suggested levels in USP.

USP 34 recommended microbial action levels

Fingertip Fingertip
(Post Fill) (Grown Validation)
CFU/plate CFU/plate
>3 >0
Classification Air Surface
CFU/m3 CFU/Plate
ISO Class 5 >1 >3
ISO Class 7 >10 >5
ISO Class 8 >100 >100

Recovery of any mold, yeast, coagulase positive staphylococcus or gram-negative rods in area is considered not to be in compliance with USP 797 standards and immediate remediation and investigation into the cause must be conducted.

General Information

  • Reports are generated as PDF files and are sent via email when finalized. Aerobiology now offers the AeroMetric 797 reporting format that simplifies your results.
  • When actionable organisms are isolated we send clients an email to alert them.
  • Standard laboratory hours for all locations are Monday-Friday 8 am to 5:30 pm, with weekend and after hours available when communicated to the lab in advance.
  • A customer support person can always be reached at any of our laboratory locations if additional support is necessary.

Referenceces and Resources

USP Services

USP 797

  • Culture, AIR, Bacterial Counts with ID* Test Code 1107
  • Culture, AIR, Fungal Counts with ID* Test Code 1108
  • Culture, SURFACE, Bacterial Counts with ID* Test Code 1104
  • Culture, SURFACE, Fungal Counts with ID* Test Code 1106
  • Culture, GLOVE FINGERTIP Bacterial or Fungal Counts Only Test Code 1109
  • Media Fill Kit & Analysis – LOW RISK Test Code 1211
  • Media Fill Kit & Analysis – MEDIUM RISK (Basic) Test Code 1209
  • Media Fill Kit & Analysis – MEDIUM RISK (Comprehensive) Test Code 1212
  • Media Fill Kit & Analysis – HIGH RISK (Basic) Test Code 1213
  • Positive Control Samples – Bacteria Test Code 1152
  • Positive Control Samples – Fungi Test Code 1153
  • USP 797 Bacterial Full Speciation (AIR or SURFACE) Test Code 1113/1115
  • USP 797 Fungal Full Speciation (AIR or SURFACE) Test Code 1141/116
  • USP 61 Microbial Enumereation of Non-sterile Products (contact lab for pricing)
  • USP 62 Microbial Testing of Non-sterile Products (ID Specific) (contact lab for pricing)
  • FLUID, Aerobic Sterility Check Test Code 3080
To learn more about USP 797 testing and our related services please request information using the form here or call us at (877) 648-9150. Thank you!