Detection of Pathogenic Legionella pneumophila in Tap Water and Water of Newborn Incubators in Hospitals of Guilan Province by PCR of mip Gene

Abstract

Aims: This study is designed to determine the frequency of Legionella pneumophila in cold and warm water as well as water containers of newborn incubators in Guilan province hospitals, Iran, using amplification of the macrophage infectivity protein gene (mip gene) by PCR. Study Design: Cross sectional study. Place and Duration of Study: The present study was performed in the Cellular and Molecular Research Center, Guilan University of Medical Sciences between June 2011 and July 2012 Methodology:  Samples were collected directly in sterile containers, concentrated in centrifuge, transferred to yeast extract broth containing L- cysteine, Fe2+, Glycin and vancomycin and incubated for 3-4 days. DNA was extracted by using the boiling method and PCR was performed to search Legionella and mip gene using two pairs of primers. Contamination with other bacteria was evaluated in all negative samples using universal primers of 16S rRNA gene. Results: About 8.5% of the samples had L. pneumophila including 11% of the incubators and 5.8% of both hot and cold tap water.  The mip gene was found in 2.8% of the samples. One third of the incubator and one half of the hot water habited L. pneumophila had the mip gene but it was not found in cold tap water samples. About 87.2% of the negative samples showed bacterial contamination as revealed by PCR with primers of 16S rRNA gene. Conclusions: This study indicates that in spite of using distilled water for incubators,         L. pneumophila contamination is considerable and other bacterial contamination is very high. It may be related to the length of time that water remains in an incubator container which is a predisposing factor for both biofilm formation and the growth of water microflora. It seems that the high temperature of hot water system and the high rate of free residual chlorine in tap water system are the main causes of low rate of Legionella contamination but are ineffective on contamination with other bacteria.