title: Virulence genes of Aeromonas isolates, bacterial endotoxins and cyanobacterial toxins from recreational water samples associated with human health symptoms.
abstract: Exposure to cyanobacterial water blooms has been associated with various kinds of adverse health effects. In addition to cyanobacteria and their toxins, the bacteria associated with cyanobacteria could also be the etiological agents. We isolated Aeromonas strains (n = 176) from water samples (n = 38) taken from sites where cyanobacteria were suspected to have caused human health symptoms, of which fever and gastrointestinal symptoms were the most common. The isolates were screened by PCR for six virulence gene types (12 genes). The majority (90%) of the strains contained at least one of the virulence genes. Most common amplification products were those of genes (act/aerA/hlyA) that encode cytotoxic enterotoxin and haemolytic products. The genes encoding cytotonic enterotoxins (ast and alt), phospholipase (lip/pla/lipH3/alp-1), elastase (ahyB) and flagellin subunits (flaA/flaB) were also present in 5-37% of the Aeromonas strains. Analysed toxins (cyanobacterial hepatotoxins and neurotoxins, and bacterial endotoxins) were not detectable or were present in only low concentrations in the majority of the samples. The results indicated that the toxins were unlikely to be the main cause of the reported adverse health effects, whereas more attention should be paid to bacteria associated with cyanobacteria as a source of health effects.
authors: Department of Food and Environmental Sciences, University of Helsinki, PO Box 56, FIN-00014 Helsinki University, Finland. katri.berg@helsinki.fi
authors: Katri A
authors: KA
authors: Berg
authors: Christina
authors: C
authors: Lyra
authors: R Maarit
authors: RM
authors: Niemi
authors: Benoit
authors: B
authors: Heens
authors: Kalle
authors: K
authors: Hoppu
authors: Kirsti
authors: K
authors: Erkomaa
authors: Kaarina
authors: K
authors: Sivonen
authors: Jarkko
authors: J
authors: Rapala
mesh_terms: D000333:Aeromonas / Q000235:genetics* / Q000472:pathogenicity; D001427:Bacterial Toxins / Q000737:chemistry*; D000087522:Cyanobacteria Toxins; D004731:Endotoxins / Q000737:chemistry*; D004784:Environmental Monitoring; D015964:Gene Expression Regulation, Bacterial; D008387:Marine Toxins / Q000737:chemistry*; D052998:Microcystins / Q000737:chemistry*; D011998:Recreation; D014774:Virulence; D014867:Water / Q000737:chemistry*; D014871:Water Microbiology; D014873:Water Pollutants
chemical_list: D001427:Bacterial Toxins; D000087522:Cyanobacteria Toxins; D004731:Endotoxins; D008387:Marine Toxins; D052998:Microcystins; D014873:Water Pollutants; D014867:Water