Assessment of Microbial Reduction by Cage Washing and Thermal Disinfection using Quantitative Biological Indicators for Spore, Virus and Vegetative Bacteria
Cage washing is a key process of the biosecurity program in rodent facilities. For the current study, we developed systems (i.e., magnet attachments, quantitative biologic indicators (Q-BI), and measurement of thermal disinfection at equipment level) to assess the microbial decontamination achieved...
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Published in | Journal of the American Association for Laboratory Animal Science Vol. 60; no. 5; pp. 1 - 10 |
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Main Authors | , , , , , , , |
Format | Journal Article |
Language | English |
Published |
American Association for Laboratory Animal Science
01.09.2021
|
Subjects | |
Online Access | Get full text |
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Summary: | Cage washing is a key process of the biosecurity program in rodent facilities. For the current study, we developed systems (i.e., magnet attachments, quantitative biologic indicators (Q-BI), and measurement of thermal disinfection at equipment level) to assess the microbial decontamination achieved by a rodent equipment washer with and without thermal disinfection. 99% of the magnets remained in position to hold Q-BI and temperature probes inside cages, water bottles or at equipment level across a cabinet washer chamber with loads dedicated to either housing or drinking devices. Various types of Q-BI for
Bacillus atrophaeus
,
Enterococcus hirae
and minute virus of mice were tested. To simulate potential interference from biologic material and animal waste during cage processing, Q-BI contained test soil: bovine serum albumin with or without feces. As a quantitative indicator of microbial decontamination, the reduction factor was calculated by comparing microbial load of processed Q-BI with unprocessed controls. We detected variation between Q-BI types and assessed the washer’s ability to reduce microbial load on equipment. Reduction factor results were consistent with the Q-BI type and showed that the washing and thermal disinfection cycle could reduce loads of vegetative bacteria, virus and spore by 5 log
10
CFU/TCID
50
and beyond. Thermal disinfection was monitored with temperature probes linked to data loggers recording live. We measured the period of exposure to temperatures above 82.2 °C, to calculate A
0
, the theoretical indicator for microbial lethality by thermal disinfection, and to assess whether the cabinet washer could pass the minimum quality standard of A
0
= 600. Temperature curves showed an A
0
> 1000 consistently across all processed equipment during thermal disinfection. These data suggest that, when sterilization is not required, a cabinet washer with thermal disinfection could replace an autoclave and reduce environmental and financial waste. |
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Bibliography: | This article contains supplemental materials online. |
ISSN: | 1559-6109 |
DOI: | 10.30802/AALAS-JAALAS-21-000026 |