Microbiological study of showerhead waters from 10 beaches of great Lisboa and West Regions of Portugal

Abstract

Many bacteria pathogenic to man can interfere in water distribution systems, forming aggregates that give rise to a complex structure called biofilm. In order to monitor the microbiological content of water from beach showers from ten sites along the coast from Lisboa-Carcavelos to Foz do Arelho beaches, 24 water samples were analyzed in 2013, 12 during January and February, and other 12 during June. The samples were collected in 500 mL sterile bottles with sodium thiosulfate. Biofilms were collected on swabs (at the same water sampling points) with transport medium Tween 20, and maintained between 2 ºC and 4 ° C, such as water samples. The following microbiological parameters were investigated for water samples: total microbial count at 22 ºC and 37 ºC, total coliforms and Escherichia coli, Pseudomonas aeruginosa, fecal streptococci, total Staphylococcus and coagulase-positive Staphylococcus. The swabs lead to the isolation of the microorganisms grown on the nutrient agar medium, in order to determine the the same microbiological parameters investigated in water showers. Globally, the water quality was found to be suitable, but that does not rule out the need for constant monitoring of the beach showers. Taking into account that there have been reports of plankton invasions and allergic eruptions after bathing in some seaside spots near Lisboa, these study results prompt us to recommend that swimmers should always shower after bathing or diving since showerheads were found safe all over the coast.