Academic journal article Iranian Journal of Public Health

The Efficacy of Residual Chlorine Content on the Control of Legionella Spp. in Hospital Water Systems

Academic journal article Iranian Journal of Public Health

The Efficacy of Residual Chlorine Content on the Control of Legionella Spp. in Hospital Water Systems

Article excerpt

Introduction

Legionella are gram-negative, aerobic, and sporeless bacteria which some of their species like Legionella pneumophila are implicated in severe pulmonary nosocomial infections (Legionnaire's Disease) and Pontiac fever, especially in immunocompromised patients, as well as in the elderly (1, 2). Indeed twenty one species of Legionella are pathogens for humans, especially in patients with the chronic pulmonary disease (3). Inhalation or micro aspira-tion of Legionella from contaminated environmen-tal sources such as hot water systems and cooling towers water is the most frequently route of trans- mission. Transmission has also been reported via nebulizer and showers in contaminated water as used (4, 5). Although, Legionella occurrence as a seasonal pattern is very common, its negative im-pact on health and hygiene requires a specific treatment cycle that is quite often a combination of management and sanitary stages. Hospitals are common habitats for the bacterium, where the bacterial niches are amply found. Hospitals pro-vide the most likely places for susceptible people to contract the diseases. Outbreaks of legionellosis have been reported from hospital patients in many countries with an incidence range of 0 to 47% (1, 5-7). Furthermore, there has been a steady in-crease in the incidence of sporadic cases reported. Consequently, national Legionella surveillance pro-grams have been established for regular monitor-ing of environmental samples in these countries (6, 8-9). In Iran, however, hospital-acquired Legion-naire's Disease has rarely been reported and envi-ronmental surveillance for Legionella in hospital water systems to provide useful data for risk as-sessment and prevention of hospital-acquired Le-gionnaire's Disease has never been systematically performed.

DNA-based techniques are innovative tools for routine quality control assessment in environmen-tal water samples and are thought to be valid al-ternatives for culture methods. The PCR is con-sidered the most adaptable and prevalent DNA-based assay technique, which is highly specific and sensitive alternative method to standard culture isolation, especially when rapid results are needed. This method is especially favorable when the samples contain abundant and diverse microbiota and when fastidious and slow-growing bacteria like Legionella are to be detected. Despite the fact that culture method for isolation of Legionella is approved by International standard Organization (ISO) and many other national standards for water quality determination; over the past few years, molecular techniques based on 16S rRNA gene beside other genetic markers have been developed to analyze bacterial communities in environmental samples (10, 11).

It is believed that the presence of Legionella is re-lated to the physicochemical characteristics of wa-ter. The correlation between the occurrences of Legionella and water quality parameters is im-portant to identify the main factors promoting the growth of Legionella in hospital water systems and to optimize the facility maintenance and operation. However, it appeared that results concerning the physicochemical characteristics of water and Le-gionella occurrence were often inconsistent or even contradictory and strong disparities in relationship have also been reported. In the context of this view, this study was conducted to investigate the presence of bacteria belonging to the Legionella genus in water supplies of some hospitals in Teh-ran, the capital city of Iran. The impact of water quality on Legionella existence was also determined. In spite of the large amount of the data available for the various indicator species in water samples, to our knowledge, this is the first attempt to gath-er information to monitor the presence of this bacterium in Iranian hospital water systems and there is no systematic study to assess the effi-ciency of chlorine disinfection. For more confir-mation, randomly two of isolates determined as Legionella spp. …

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