A study on the actual conditions associated with the presence of Acinetobacter sp. in a hospital waiting room

Abstract

In recent years, nosocomial infection, including that by multiple-drug-resistant Acinetobacter (MDRA), has become an increasing concern in Japan. Typically, Acinetobacter inhabits soil and river water and is usually harmless to humans. However, bacteria of this genus can become pathogens in inpatients with weakened immune systems, resulting in opportunistic infection. Currently, hospital infection by MDRA is spreading not only in Japan, but also worldwide. This is a very serious problem, and little is known about effective countermeasures. The present study sought to examine the microbiome status in a hospital visitor waiting room as a first step in establishing countermeasures for use against Acinetobacter. Specifically, we performed a so-called metagenomic analysis to directly analyze DNA collected from the environment, without an intervening cultivation step. Indoor airborne bacteria and surface bacteria were sampled and analyzed. The results show that in a visitor waiting room, the top-ten most-abundant genera included (in decreasing order) Acinetobacter, Streptococcus, Prevotella, Pseudomonas, Bifidobacterium, Fusobacterium, Neisseia, Porphyromonas, Leptotrichia, and Haemophilus. Thus, Acinetobacter constituted the mostdetected genus and was present in all collected samples. Furthermore, we assessed the bactericidal effect of ultraviolet C (UVC) against Acinetobacter sp. 7206, a hospital isolate. A UVC dose of 4.0 sec•mW/cm2 was required to kill the 99.9% Acinetobacter sp. 7206 on solid culture medium.