Bacterial Test Methods

Phenol Coefficient Test. The first important attempt at standardizing testing methods was known as the phenol coefficient test (96). It has been modified several times, and is an official AO AC screening test recognized by EPA and PDA. The phenol coefficient test compares the activity of disinfectants to that of phenol, under specific conditions, to give a number that measures the activity of the chemical tested with respect to that of phenol, ie, the phenol coefficient. The AO AC method employs visual examination of bacterial growth in a nutrient medium. The Kelsey-Sykes test (1969) is a modified method popular in British circles. 

In all antiseptic testing, it is recognized that skin and mucous membranes to which products ate appHed cannot be disinfected or sterilized but it is possible to significantly reduce the population of transient and resident pathogenic bacterial flora. AH in vivo test methods requite a deterrnination of the bacteria on the skin before and after treatment. Because of the normal variation in bacterial population of the skin of different people, a number of people must be tested in order to make a statistical analysis of the results. Different parts of the body are used for different tests. In aH of the tests the details of the protocol ate extremely important and must be strictly adhered to in order to obtain reproducible results. 

The Kelsey-Sykes (KS) test. Having regard to the many disadvantages alleged against the RW and CM tests, attempts were made and published in the early 1960s to find improved test methods. The foundations for the new test were laid by Kelsey et al. in 1965, and with the collaboration of the late G. Sykes and ofisobel M. Maurer, the Kelsey-Sykes test was evolved. This test embodied several principles. Firstly, it was a capacity test. Here a bacterial inoculum was added to the disinfectant in three successive lots at 0, 1 and 5 minutes. This is the principle of a capacity test where the capacity or lack of capacity ofthe disinfectant to destroy successive additions of a bacterial culture is tested. 

API Serial Dilution Method. The API serial dilution method is the most widely used method for the detection of microorganisms. Field test methods for estimating bacterial populations have been standardized. A standard method dealing with the dose-response (time-kill) testing for evaluating biocides has been established. Sampling methods are of special importance because effective sampling is essential to any successful analysis. 

A variety of methods are available to test a chemical for mutagenicity, i.e., its effect on the genetic material. The Ames Test has gained most recognition as a shortterm test [23],This is a bacterial test which allows fast performance and requires limited expense. Its correlation with the mutagenicity of mammals or even with a carcinogenic effect on mammals or humans has repeatedly been tested [24], but remains controversial. 

The bioluminescent direct contact flash test has been proposed as a modification of the direct contact luminescent bacterial test [24,38]. This method was developed for measuring the toxicity of solid and color samples, and involves kinetic measurements of luminescence started at the same time that the V. fischeri suspension is added to the sample. The luminiscence signal is measured 20 times per second during the 30 second exposure period. 

Bacterial endotoxin kinetic test or gel clot limit standard test method (provide reference number)... 

D 4299 Test Methods for Effect of Bacterial Contamination on Permanence of... 

Industrial firms should be encouraged to develop test methods for accelerated storage stability determination for bacterial larvicides. 

The industry should be encouraged to evaluate the applicability of CIPAC and WHO test methods for quality control of bacterial larvicides. 

Industry should provide the relevant test methods to determine the identity and content of the active ingredients of bacterial larvicide products. 

Standard Test Method for Determining Bacterial Retention of Membrane Filters Utilized for Liquid Filtration, Standard F838-83 Revised 1988 American Society for Testing and Materials (ASTM), 1983. 

The General Tests, Processes, and Apparatus section contains 60 test methods, such as fluorometry and electrometric titration, dissolution and disintegration tests, content uniformity, and a bacterial endotoxin test. Qualitative tests, reagents and test solutions, and standard solutions are also included. The Infrared Reference Spectra of 124 chemical entities are included in an appendix and will be updated in subsequent editions. 

These biocides are usually provided to offer a value added component to existing applications. An example would be an anti-bacterial chopping board promoted as a safer alternative to a board that does not claim to have any anti-bacterial additive. However, there are no internationally recognised test methods available to prove the performance of such systems and so most applications are based either on certain laboratory test protocols, anecdotal evidence of performance or by marketing claims alone. 

We must also realize that the clinical simulation models also test efficacy against resident bacterial populations that are not representative of the species encountered in a clinical setting. The subjects used in these studies are not healthcare personnel, and their microbial flora may not represent the types or numbers of organisms found on the hands of healthcare personnel. In addition, the hands of healthcare personnel are more likely to encounter antibiotic-resistant organisms that become transient or colonizers on their hands. Thus, the predictive value of these test methods, given this difference, must also be considered in the evaluation of test products. 

Validation of the neutralization system is one of the most critical, if not the most critical, aspects of the preclinical and clinical studies. Recall that assessment of the efficacy of a product in the time-kill kinetic study and the clinical simulation studies is based on the measurement of a bacterial population from an established baseline. Basically, these test methods are designed to capture a snap shot of the time-kill proAle so that when a sample is taken, immediate neutralization must take place. TheoreAcally, this provides an accurate enumeradon and subsequent calculation of reduction from a predetermined baseline. 

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