Avaliação da contaminação microbiológica por meio do método convencional e Petrifilm™ em equipamentos e acessórios utilizados em radiografias digitais

Abstract

The aims of this study were to compare the rate of microbiological contamination, before and after clinical treatments, in surfaces of digital radiography equipment of the Faculty of Dentistry of the Federal University of Juiz de Fora; to compare the contamination between the Radiology and multidisciplinary clinics; and correlate two methods used to collect microorganisms. Samples were collected from the surfaces of periapical X-ray machines (head, arm joints, control panel and shutter button), the digital radiography system (sensor) and the computer of digital system (keyboard and mouse), using two distinct methods: the method of smear surface with sterile swabs (conventional) and the method of direct contact with the plate PetrifilmTM. The samples were grown in different culture media and after 48 hours of incubation, colonies were counted. Bacterial colonies presumptively isolated by conventional method were subjected to biochemical tests for identification of Stafilococcus, Streptococcus and Gram-negative bacilli. No biochemical test was carried out for mold/yeast. For comparison between samples taken before and after clinical procedures we used the Wilcoxon test. For comparison between the two clinics was used the Mann-Whitney test. The Spearman coefficient was calculeted to assess the correlation between the methods of collection. A total of 252 samples were collected, divided between both methods. Streptococcus were not identified. After the biochemical tests for Stafilococcus isolates by the conventional method, only one S. aureus (1.25%) was isolated from the shutter button on the multidisciplinary clinic, 16.25% were identified as S. saprophyticus and 82.50% characterized as S. epidermidis. Among Gram-negative bacilli were identified: Chromobacterium violaceum, Pseudomonas pseudoalcaligenes, Ochrobactrum anthropi, Pseudomonas putida, Brevundimonas vesicular. Unable to recover the colonies collected by PetrifilmTM. It can be concluded that the microbial counts were higher before treatment in the multidisciplinary clinic. There was no significant correlation between the sampling methods tested.