Identification of microorganisms in water samples used in refractive surgery facilities

Abstract

Purpose: To identify the presence of microorganisms in different systems of water delivery to steamer devices used in sanitisation routine procedure for laser in-situ keratomileusis in three different refractive surgery centers

Methods: Environmental samples of water were collected after a routine activity in three different refractive surgery centers, that used the same model of steamer. Two centers used tap water that underwent filtration and distillation, and was stored in non sterile gallons. Water samples were collected from the tap, filter hose, distillation outlet and collector, and storage gallons. The third center used sterile distilled water and a water sample was collected from the water bag. Samples from the steamer reservoir, hose and condensed water from the steamer outlet were collected from all devices. All samples were then vacuum filtered through 0.45 µm nylon membranes (Millipore), decontaminated by cetylpyridinium chloride 0,05%(CPC) and plated on Middlebrook 7H10-OADC agar, 7H10-OADC-Panta and Löwenstein-Jensen medium. Acid-fast bacilli detected in culture were identified by PCR-Restriction Enzyme Analysis of hsp65 gene (PRA-hsp65) and typed by Pulsed Field Gel Electrophoresis (PFGE)-DraI. Other bacteria were identified by Phoenix Automated System.

Results: In two centers, microorganisms were identified in different samples of water. In the first center, Mycobacterium chelonae was isolated from the distilled water storage gallons and steamer reservoir. Mycobacterium mucogenicum was isolated from tap water. All M. chelonae isolated colonies showed the same PFGE pattern, confirming that a single strain was present in the distilled water and storage gallons. Other aerobic bacteria were isolated from the storage gallons and steamer reservoir. In the second center, M. chelonae was isolated in samples from the tap and filter hose, and other aerobic bacteria were found in water samples from the distillation outlet and collector, storage gallons, steamer reservoir and hose. Samples collected from the third center, that used sterile distilled water, showed no evidence of microorganisms growth after cultures.

Conclusions: Our results show that the use of distilled tap water in sanitisation care of surgical instruments could be a potential source of contamination. The methodology applied to this study was appropriate to identify aerobic, anaerobic and mycobacteria.

Keywords: 467 clinical laboratory testing • 465 clinical (human) or epidemiologic studies: systems/equipment/techniques • 683 refractive surgery: LASIK