Comparative Levels and Types of Microbial Contamination Detected in Industrial Clean Rooms

Abstract

Comparative levels and types of microbial contamination detected in industrial clean rooms. Appl. Microbiol. 14:539-551. 1966.-The primary objective of this study was to determine quantitatively and qualitatively the predominant types of microbial contamination occurring in conventional and laminar flow clean rooms. One horizontal laminar flow, three conventional industrial clean rooms, and three open factory areas were selected for microbiological tests. The results showed that as the environment and personnel of a clean room were controlled in a more positive manner with respect to the reduction of particulate contamination, the levels of airborne and surface microbial contaminants were reduced accordingly. The chief sources of microbial contamination were associated with the density and activity of clean room personnel. In addition, the majority of microorganisms isolated from the intramural air by air samplers were those indigenous to humans. Studies on the fallout and accumulation of airborne microorganisms on stainless-steel surfaces showed that, although there were no significant differences in the levels of microbial contamination among the conventional clean rooms, the type of microorganism detected on stainless-steel surfaces was consistently and significantly different. In addition, the "plateau phenomenon" occurred in all environments studied. It was concluded that the stainless-steel strip method for detecting microbial accumulation on surfaces is efficient and sensitive in ultra-clean environments and is the most reliable and practical method for monitoring microbial contamination in future class 100 clean rooms to be used for the assembly of spacecraft which will be sterilized.

Dispersal of skin microorganisms

“…In industry Sykes (1970) has pointed out that a room can be designed and maintained 'virtually sterile' tintil it is occupied by himians; such conditions are required for sterile filling of injectable materials. Favero et al (1966) have reported essentially similar studies whilst Behagel & Berg (1973) reported on the difficulty of maintaining staphylococcal cultures free from the risk of contamination by phage derived from strains carried by personnel. In a hospital situation the gravest risk is in the operating theatre (Payne, 1967;Ayliffe & Collins, 1967;Charnley, 1973), but there is also a general risk in the excessive dispersal of organisms into the air of wards (Hamburger, Green & Hamburger, 1945;Schaffner et al, 1969).…”

Animal and Environmental Impact on the Presence and Distribution of Salmonella and Escherichia coli in Hydroponic Tomato Greenhouses

“…However, working shoes were not used exclusively inside the greenhouse, but were also worn to go from one facility to another. Shoes have seldom been mentioned as vehicles of contamination in food production areas (8). This dissemination mechanism of enteric pathogens should be considered as an important control point during working procedures in greenhouses.…”

“…In addition, shoes carrying animal feces positive for Salmonella (F serogroup strains) may be vehicles of contamination into the greenhouses. A discreet, but important number of samples from puddles (8) and soil (11) were also positive for pulsotypes isolated from tomatoes. As noted by Baloda et al (1) and Wonderling et al (22), some pulsotypes may be more able to adapt and survive on specific environments of production facilities.…”

Techniques Used for Sampling Airborne Microorganisms Associated With Industrial Clean Rooms and Spacecraft Assembly Areas

“…Even when personnel and density activity were high and samplers were placed downstream from personnel the maximum level of viable particles per cubic foot of air was about 1-2 in horizontal laminar flow clean rooms. Under similar circumstances in vertical laminar flow clean rooms it was not uncommon to detect less than [5][6][7][8][9][10] viable particles per 100 cubic feet of air. These contamination levels were several orders of magnitude lower than those obtained in conventional clean rooms and surgical suites.…”