TIM SANDLE
Bio Products Laboratory, Elstree, United Kingdom

Abstract

This study was undertaken to determine whether TSA contact plates, formulated with a disinfectant neutraliser, were suitable for use in the detection and enumeration of microorganisms from surfaces for environmental monitoring sampling as relating to a pharmaceutical facility.  Contact plates are the primary method of choice for quantitatively sampling flat surfaces and floors for the presence of microorganisms. For the study a range of representative microorganisms were selected, and two surface material types were used: stainless steel and vinyl. The results showed a variable recovery across the two different surfaces and between the different types of microorganisms, with a mean of 55% for a 10 second contact time. This information demonstrates the relative efficiency of the contact plate for cleanroom environmental monitoring.

INTRODUCTION

Microbiological environmental monitoring is an important part of a biocontamination control strategy, and it acts as an effective tool, provided a risk-based approach has been used for such aspects as sample selection and for determining monitoring frequencies (1). The microbial assessment of pharmaceutical facility environments is undertaken using established methodologies for air and surface sampling. Surface sampling techniques are the swab and contact plate. These are culture based environmental monitoring methods and they are limited based on the type and formulation of the culture medium selected. There is no ‘universal culture medium’ and there are no set of incubation conditions that can recover all cleanroom isolates, with respect to temperature and time. This is both a product of the regime selected and due to the nature of non-culturability, which is both medium dependent and a factor of many cleanroom isolates being sublethally damaged under conditions of stress which impart a fragility that makes recovery on standard media very difficult (2).

With this general limitation accep ...