Aeromonas presence in drinking water from collective reservoirs and wells in peri-urban area in Brazil

Abstract

Aeromonas genus is considered an emerging pathogen and its presence in drinking water supplies is a reason to public health concern. This study investigated the occurrence of Aeromonas in samples from collective reservoirs and wells used as drinking water sources in a peri-urban area. A total of 35 water samples were collected from collective reservoirs and 32 from wells bimonthly, from September 2007 to September 2008. Aeromonas spp determination was carried out using a Multiple-Tube Technique. Samples were inoculated into alkaline peptone water and the superficial film formed was transferred to blood agar plates amended with ampicillin. Typical Aeromonas colonies were submitted to a biochemical screening and then to biochemical tests for species differentiation. Aeromonas was detected in 13 (19%) of the 69 samples examined (6 from collective reservoirs and 7 from wells). Concentrations of Aeromonas in collective reservoirs ranged from <0.3 to 1.2 x10 2 MPN/100mL and, in wells, from <0.3 to 2.4 x10 2 MPN/100mL. The most frequent specie in the collective reservoir samples was Aeromonas spp (68%), followed by A. encheleia (14%) and A. allosaccharophila (8%) and A. hydrophila (8%). Aeromonas spp (87%) was the most frequent specie isolated from well samples, followed by A. allosacchariphila (8%), A. encheleia (2%) and A. jandaei (5%). These data show the presence and diversity of Aeromonas genus in the samples analyzed and highlight that its presence in drinking water poses a significant public health concern.

Shortcomings of the Multiple Tube Test for Bacteria in Drinking Water

“…Similar is the case with Aeromonas spp. which can cause waterborne infections like gastroenteritis and is notoriously resistant to Chlorine disinfectants [5] . Aeromonas spp.…”

“…Aeromonas spp. in drinkig water should be of teremendous public health concern because of their ability to form toxins and biofilms [5] . Reports mention use of specific tests like Multiple tube test using alkaline peptone water and then subculture on to Ampicillin blood agar for detecting Aeromonas spp [5] .…”

“…in drinkig water should be of teremendous public health concern because of their ability to form toxins and biofilms [5] . Reports mention use of specific tests like Multiple tube test using alkaline peptone water and then subculture on to Ampicillin blood agar for detecting Aeromonas spp [5] . Even Pseudomonas aeruginosa is harmful if detected in drinking water because in people taking antibiotics to which it is resistant, this pathogen can cause gastritis and also skin infections and aerosol mediated respiratory infections [6] .…”

An Approach Using Non‐Conventional Indicators for Detecting Microbial Water Pollution

“…In this respect, the European community has established a drinking water standard for Aeromonas of no more than 20 CFU/100 mL in water leaving the treatment plant and 200 CFU/100 mL in distribution systems [42]. Similarly, Aeromonas have been detected in chlorinated drinking water from distribution systems in Italy, Mexico City, Brazil, and the United States [17,18,37,43]. This shows their capacity to survive and multiply within biofilms on the surfaces of pipes [44], as well as their relative resistance to chlorination [45][46][47].…”

“…Recent researches showed that they are almost equally important as coliforms in water quality monitoring programs. Even more, in some countries Aeromonas are now considered better indicator of contamination than general coliforms .…”