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DETERMINING
THE APPROPRIATE MICROBIAL CHALLENGE
A biological
indicator (BI) is an “inoculated carrier contained within
its primary pack providing a known resistance to the
relevant process.”
4 There are many different types of BIs but the most
common include:
BI PLACEMENT IN THE PRODUCT LOAD
After the product load challenge has been identified,
the BI positioning and placement can be determined. BIs
should be distributed throughout the product load and, as
much as possible, in the same orientation (e.g.,
vertical).
The placement must include those locations that are
considered to present the greatest challenge to the
process and can be the same as those used for temperature
monitoring. The ANSI/AAMI/ISO 11135-1994 standard suggests
placing two BIs at each location with a
temperature-monitoring device in order to obtain
additional information on process efficacy.
HALF-CYCLE METHOD
The half-cycle method determines the minimum time a
specific product load must be exposed to an EtO process to
guarantee that no survivors exist from the BIs used to
monitor the cycle’s efficacy. The cycle chosen is based on
the microbiological data obtained prior to determining the
parameters for the half-cycle sterilizer chamber volume
above 10 m3.
EtO validation: the microbiological performance
qualification (MPQ).
Choose the appropriate microbial challenge for an EtO
sterilization process, develop the EtO cycle, product
load, placement of biological indicators in/on the product
load, determine cycle lethality, calculate the D-value.
Information is also given on the documentation for the
report on validation and certification of the process, and
revalidation is discussed briefly. Some suggestions exceed
the current requirements presented in international
standards, but they can enhance a validation process,
resulting in a more thorough and accurate study.
The critical parameters of an EtO sterilization cycle
are typically given as temperature, pressure, humidity,
EtO concentration, and gas dwell time. However, the
process engineer must also identify and evaluate
relationships that may exist between any given process
parameter(s), the product being sterilized, and the
equipment used.
The sterilization process must consistently deliver all
critical process parameters to each and every component
contained within the load, to a degree that will ensure a
10-6 sterility assurance level (SAL) without causing any
deleterious effect to the product or its sterile barrier
packaging. In addition, this process must occur under
controlled conditions that will protect the sterilization
personnel monitoring the operation, the equipment
employed, and ultimately the end-user.
DETERMINING THE APPROPRIATE PRODUCT LOAD CHALLENGE
Microbiological performance qualification (MPQ) should be
performed using specified products and packaging
configured in the same manner in which they will be
routinely sterilized. For the cycle to be accurate, the
product load must represent the greatest challenge
intended for future routine sterilization. Each type of
configuration must be documented in terms of the number of
product units per case, the number of cases per pallet,
the stacking patterns on the pallet, and the density. This
documentation should be included with the validation data.
REPORT ON VALIDATION AND CERTIFICATION INCLUDES:
References to the maintenance and calibration
procedures
Specifications for the EtO chamber
The validation protocol.
A description of the products used as test samples,
including packaging.
BI certification and data
The physical and biological records from all of the
validation cycles. Placement diagrams and data for the
monitoring devices (including temperature, gas
concentration, and relative humidity).
Documentation on and verification of the positioning
and location where theBIs and product test samples were
placed on the product load.
References to the test procedures used during the
validation.
A complete description of the products Documentation of
operating procedures, including process control limits.
A test report summarizing and analyzing the validation
data. |
