Significant inter-strain variability is reported in conditions for growth and survival.
Optimum 28 to 35°C. Range-2 up to 42-45°C, although often < 40°C depending on the strain
Optimum 7.2, Minimum 4.5, Maximum ≥ 8.7. Unlikely to grow in food below pH 6.0 and stored at low temperatures
Optimum approximately 1-2% NaCl
At pH 4.5, no growth observed at 4 or 28°C
4.5% (~0.975 aw) NaCl inhibits growth for >14 days at 4°C. At 28°C 5% NaCl (~0.97aw) inhibits most strains and 6% NaCl inhibits them all.
D45°C = 12-29 minutes. In saline (0.85% NaCl), D48°C = 2.2-6.6 minutes and D51°C = 1.2-2.3 minutes
Inactivated at values <4.5
< 0.96 aw (~ 6 to 7% NaCl) controls all strains tested. Susceptible to disinfectants, including sodium hypochlorite and quaternary ammonium compounds. Also iodophors, 2-chlorophenol and glutaraldehyde.
Prevalence comparisons between symptomatic and asymptomatic individuals show higher values for those with symptoms, but the ranges are broad and overlapping. The organism is, however, not considered to be a normal inhabitant of the gut.
May colonise aquatic plants and animals e.g. fish, leeches and frogs. Causes disease in animals associated with water, e.g. reptiles, fish, shellfish and snails. Minor flora component of domestic animal faeces (pigs, cows, sheep, poultry). Has been isolated from houseflies, mosquitoes and ticks (Galindo and Chopra, 2007). Recently isolated from faeces of Macaca fascicularis, a primate (Harf-Monteil et al., 2004).
Organism has been isolated from fresh produce (McMahon and Wilson, 2001) and foods of animal origin, such as meat, raw milk, poultry, fish, and shellfish.
Found in salt, fresh, stagnant, estuarine and brackish water worldwide. Tends more towards freshwater because as salinity increases, recovery of organism decreases. Also isolated from soil, sewage, and even tree bark. Its isolation from water and sediments decreases during cooler months. Typing data have been reported supporting water to human transmission (Khajanchi et al, 2010).
Via water and possibly by ingestion of foods including seafood, particularly oysters that receive little or no cooking during their preparation.
Seasonal variation observed with Aeromonas-
associated gastroenteritis peaking in warmer months. Collated information on 16 outbreaks/incidences of Aeromonas-
associated gastroenteritis implicated a range of suspect foods including fish, land snails, oysters, prawns, shrimp cocktail, dried fish sauce and egg salad. Adults are the largest age group reported among cases. Larger, suspected, outbreaks include:
Louisana, USA, 472 adult cases (A. hydrophila)
Dried fish sauce
France, 10 adult cases
Mixed meal including seafood, meat and offals
Sweden, 27 people (A. hydrophila)
Don’t forget to read the disclaimer
! It is likely that some strains of Aeromonas
cause gastroenteritis, but the role of members of this genus in foodborne illness remains controversial.
1-2 days. In an outbreak of A. caviae infections in France, the mean incubation time was 10.6 hours.
Broad spectrum of symptoms ranging from mild, self-limiting watery diarrhoea to dysentery. Abdominal pain, nausea, chills, headache and colitis may also occur. Symptoms last 1-7 days. Chronic diarrhoea has also been reported, usually 7-10 days. A. veronii biovar sobria has been associated with severe gastroenteritis with dysenteric symptoms. Some strains produce aerolysin, which is toxic to vero cells, and a number of haemolytic uremic syndrome cases have been attributed to such strains.
In one human trial where up to 1,000 cells were given, only two of 57 (healthy) volunteers developed diarrhoeal symptoms.
At Risk Groups
Immunocompromised individuals including adults with disrupted gastrointestinal flora. Symptoms are more severe for children.
Long Term Effects
Older patients more likely to present with chronic enterocolitis.