Moist Heat Disinfection and Revisiting the A0 Concept.

Moist heat is employed in the medical device, pharmaceutical, and food processing industries to render products and goods safe for use and human consumption. Applications include its use to pasteurize a broad range of foods and beverages, the control of microbial contamination of blood products, and treatment of bone tissue transplants and vaccines. In the pharmaceutical industry, water heated to 65°C to 80°C is used to sanitize high-purity water systems. In healthcare, it has been employed for decades to disinfect patient care items ranging from bedpans to anesthesia equipment. There is a good understanding of the conditions necessary to achieve disinfection of microorganisms at temperatures ranging from 65°C to 100°C. Based on this information, the efficacy of moist heat processes at a range of exposure times and temperatures can be quantified based on mathematical models such as the A0 calculation. While the A0 concept is recognized within the European healthcare community, it has yet to be widely adopted within the United States. This article provides information regarding the A0 concept, a brief overview of the classification of thermal disinfection for use with healthcare applications within the United States, and recent data on reinvestigating the thermal disinfection of a selected panel of microorganisms and a mixed culture biofilm.

Evaluation of a rapid microbiological method with a mixed culture biofilm model.

During the past decade, rapid microbiological methods (RMMs) have continued to make inroads into the pharmaceutical and medical device industries. This has led to the development of guidelines for the validation of alternative microbiological methods for both quantitative and qualitative applications. Many studies regarding RMMs have focused on testing performed with planktonic microorganisms. In some applications there is the possibility that microorganisms may also be present as biofilms. When evaluating an RMM, consideration should be given to the potential for biofilm formation within the context of the application and whether microorganisms derived from biofilm would influence the response of the method. This study reflects the evaluation of an RMM with both planktonic microorganisms and microorganisms derived from a mixed culture biofilm. LAY ABSTRACT: Many new rapid microbiological methods (RMMs) have been developed that have the potential to replace conventional microbiological methods in a wide range of applications including sterility testing, microbial enumeration, environmental monitoring, microbial identification, and other areas. Qualification of these new methods is frequently based on testing performed with planktonic (non-aggregated) microorganisms. However, microorganisms can aggregate together to form biofilms in both natural and manufacturing environments. Purified water systems in particular may be susceptible to the development of biofilms. Because the properties of microorganisms in a biofilm may differ from those in a planktonic state, qualification of an RMM with microorganisms derived from a relevant biofilm model may be appropriate depending on the application and the potential for biofilm formation. This study describes the evaluation of one such RMM, the Chemunex ScanRDI®, with both planktonic microorganisms and microorganisms derived from a mixed culture biofilm model.

Ophthalmic viscoelastic devices as a cleaning challenge.

Common practice when validating the cleaning of medical devices is to employ clinically relevant test soils as a challenge to the cleaning process. During use, medical devices may come into contact with a variety of materials that are difficult to clean. One example of this is the use of ophthalmic viscoelastic devices (OVDs) in cataract surgery. This study evaluated the effectiveness of a procedure for cleaning the lumens of a phacoemulsification handpiece using two different OVDs as test soils. The results of this study demonstrate that effective cleaning of the aspiration and irrigation lumens of a phacoemulsification handpiece may be achieved if the manufacturer's recommended cleaning procedures are followed.

A designed experiment for evaluation of the OPA method for cleaning studies of medical devices.

This study reports the results of a designed experiment to evaluate the use of the o-phthalic dialdehyde (OPA) method for residual protein, with a testsoilderivedfrom blood, dehydrated hog mucin, and egg yolk, and its application in validating the automated cleaning of surgical instruments in a laboratory setting. The ruggedness and robustness of the OPA method was determined by means of a Plackett-Burman experimental design and assessed the automated cleaning of a microkeratome for use in patients undergoing lamellar resection of the cornea during refractive surgery. The outcome of the study indicates that the OPA method for residual protein is rugged and robust for the factors evaluated and is an effective means for validating the cleaning of complex medical devices under controlled laboratory conditions. The components of the microkeratome contaminated with the test soil were successfully cleaned in an automated washer-disinfector using a neutral pH detergent and the procedure as described.