Isolation and Identification of <em>Legionella</em> spp. in environmental water sources based on macrophage infectivity potentiator (<em>mip</em>) gene sequencing in southwest Iran

Abstract

Legionella species are widespread in natural water sources and man-made aqueous environments, as well as fresh-water. The present study was conducted owing to the lack of research regarding the prevalence of Legionella spp in the water sources of Ahvaz city in southwest Iran. In this study the macrophage infectivity potentiator (mip) gene sequencing was used for identification of various Legionella species isolated from different water sources. In this study, 144 water samples were collected and inoculated on the buffered charcoal-yeast extract (BCYE) agar and modified Wadowsky-Yee (MWY) medium. The DNA was extracted from positive cultures. The Legionella species were confirmed by amplifying a 654 bp fragment of the 16S rRNA gene. The mip gene of all isolates were amplified by PCR and purified for sequencing. The mip gene sequences were analyzed by jPHYDIT software version 1. The results showed a 13.9% (20/144) prevalence of Legionella spp. in water sources of Ahvaz city, southwest Iran. Analyzing of the mip gene sequences showed, out of 20 Legionella isolates, 13 isolates (54.1%) were positive for L. pneumophila, 5 isolates (20.8%) were positive for L. worsleinsis, one isolates for each one of L. dumoffi and L. fairfieldensis, (4.1%). According to our research, the occurrence of Legionella spp in water sources could be a hazard for the health systems especially in the hospitals. The regular monitoring of these water sources by health planners may therefore be useful for decreasing the risk for Legionella spp. infections.

Correlation between Legionella pneumophila serogroups isolated from patients with ventilator-associated pneumonia and water resources: a study of four hospitals in Tehran, Iran

“…Also, 60.8% of positive samples from water resources belonged to serogroup 1 in our study. Based on other reports from different regions of Iran, serogroup 1 is more frequently found in water resources (Moosavian et al 2019;Yaslianifard et al 2019), although it varies in other countries (Den Boer et al 2008;Harrison et al 2007). The distribution of legionella isolates may depend on the location and geographical area, as shown in a study from Korea (Lee et al 2010).…”

Occurrence of the Legionella species in the respiratory samples of patients with pneumonia symptoms from Ahvaz, Iran; first detection of Legionella cherrii

“…To date, several studies have investigated the prevalence of different species of Legionella in clinical and environmental samples in various regions of Iran through conventional and modern methods including culture, urinary antigen test, PCR, and LAMP [13,14,17]. However, according to the available information, no study has been conducted to investigate the presence of different species of Legionella by the real-time PCR gene method targeting the 23S-5S rRNA gene spacer region and sequencing of this gene in clinical samples in Iran.…”

“…The colonies that resembled the Legionella spp were selected for further evaluation by standard bacteriological tests including Gram-staining, catalase, oxidase, and other biochemical tests. Besides, a number of colonies were cultured on a conventional unselective culture media such as sheep blood agar and MacConkey agar that lacked L-cysteine and incubated under previous conditions [13,14]. The isolates that were found to be Gram-negative rods under the microscope and were not able to grow on cysteine-free media were considered as Legionella species.…”

“…Over 90% of legionellosis infection being caused by L. pneumophila belonging to 16 serological groups, of which Lp 1 contributed to 80% of cases [9][10][11]. So far, various methods including enzyme-linked immunosorbent assays (ELISA), polymerase chain reaction (PCR), loop-mediated isothermal amplification (LAMP), and real-time PCR have been introduced to detect the Legionella species in clinical and environmental samples, however, the culture method is still considered as the gold standard diagnostic method [9][10][11][12][13][14]. In recent decades, due to the disadvantages of the culture method, including time-consuming and need for specific media, reliance on more modern methods such as nucleic acid amplification tests (NAATs) and whole genome sequencing has increased [5,6,9].…”

“…In recent decades, due to the disadvantages of the culture method, including time-consuming and need for specific media, reliance on more modern methods such as nucleic acid amplification tests (NAATs) and whole genome sequencing has increased [5,6,9]. The NAAT methods are mostly based on the detection of genes encoding the macrophage infectivity potentiator (mip), 5s rRNA and 16s rRNA subunits, and the 23S-5S rRNA gene spacer sequence in Legionella species [9,13].…”