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Enteropathogenicity of Aeromonas species isolated from infants: a cohort study
1Microbiology Unit, University of Chile, Santiago.
Insights
Certain Aeromonas species are significant enteric pathogens in infants, causing prolonged diarrhea. Virulence factors like invasiveness and enterotoxigenicity are key to their pathogenicity, necessitating targeted antibiotic treatment.
Area of Science:
- Microbiology
- Pediatric Infectious Diseases
- Bacteriology
Background:
- Aeromonas species are increasingly recognized as potential causes of infant gastroenteritis.
- Understanding the virulence factors of Aeromonas strains is crucial for accurate diagnosis and treatment.
Purpose of the Study:
- To evaluate the role of Aeromonas species as enteric pathogens in infants.
- To characterize the virulence-associated properties of isolated Aeromonas strains.
- To determine the clinical significance of Aeromonas infections in pediatric diarrhea.
Main Methods:
- A cohort study involving 187 infants aged 3-18 months over a 16-week summer period.
- Isolation and identification of Aeromonas species from diarrheal and asymptomatic fecal samples.
- Assessment of virulence factors including enterotoxigenicity, invasiveness, and beta-hemolysis.
- Plasmid analysis and antibiotic resistance profiling of selected isolates.
Main Results:
- Aeromonas species were isolated from 7.1% of diarrheal episodes and 5.2% of asymptomatic controls.
- Enterotoxigenicity, invasiveness, and beta-hemolysis were common in Aeromonas sobria but absent in Aeromonas caviae.
- Aeromonas hydrophila isolate showed cytotoxic enterotoxin production and invasiveness.
- Diarrheal episodes associated with invasive and/or toxigenic Aeromonas strains lasted significantly longer (17.2 days vs. 4.3 days).
- Antibiotic resistance was observed in a significant proportion of isolates.
Conclusions:
- Virulence determinants must be characterized to assign pathogenic roles to Aeromonas species.
- Invasive and/or enterotoxigenic Aeromonas strains are associated with prolonged diarrhea in infants.
- Adequate antibiotic therapy is recommended for infants with confirmed infections by virulent Aeromonas strains.
Abstract:
The significance of Aeromonas spp. as potential enteric pathogens was evaluated in a cohort of 187 infants aged 3-18 months during a 16-week summer period. Aeromonas spp. were isolated from 14 of the 196 (7.1%) diarrhoeal episodes detected and from eight (5.2%) of 153 samples from paired asymptomatic infants. Carriage of bacterial enteropathogens excluding Aeromonas spp. was detected in a high proportion (23%) of the asymptomatic children. Almost all of the seven isolates of Aeromonas sobria were enterotoxigenic, invasive and beta-haemolytic. In contrast, none of the seven Aeromonas caviae strains had these virulence-associated characteristics. The only isolate of Aeromonas hydrophila produced cytotoxic enterotoxin and was invasive. Plasmid analysis of selected strains did not correlate with these two properties or with antibiotic resistance. Nevertheless, the latter was found in an important proportion of the isolates. The diarrhoeal episodes, in which Aeromonas spp. were detected, lasted significantly longer, i.e. 17.2 days when the strains were invasive and/or toxigenic as compared with 4.3 days (P less than 0.001) in patients harbouring strains lacking both traits. These results reinforce the need to characterise virulence determinants before assigning any pathogenic role to Aeromonas spp. isolated from faecal specimens. Our findings also suggest the need for adequate antibiotic treatment in patients with confirmed Aeromonas spp. having enterotoxigenic and/or invasive properties.