Sources of the slow-growing pigmented water bacteria.

The group of organisms often labelled as "slow-growing pigmented water bacteria" may include various species of the Xanthomonas, Cytophoga, Pseudomonas, Aeromonas and Flavobacterium genera. Due to their slow growth, this group is usually overlooked in the average clinical laboratory since the pigmented colonies are most easily noted on membrane filter pads or on surface streaked agar plates, but only after 5-15 days of incubation at room temperature. Although present at low levels in free-flowing domestic water supplies (less than 1 per ml), they can be easily isolated by swabbing sink faucets, drinking fountain heads, surgical scrub sink heads and aerators, dental chair spray units, and from the air water interface in humidifiers, nebulizers, water baths, and reservoirs where the water may remain static for weeks. Although not considered primary pathogens, several strains have been implicated in infections in nurseries and among patients in intensive care units. Contamination control in critical research and patient care areas demands scrupulous sanitation practices, regular cleaning and decontamination of all equipment, and the use of bacteria-free water whenever possible.