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Prevalence, virulence and antimicrobial resistance patterns of Aeromonas spp. isolated from children with diarrhea
Mohammad Mehdi Soltan Dallal1, Ramin Mazaheri Nezhad Fard2, Morteza Kavan Talkhabi3
1PhD, Professor of Microbiology, Division of Food Microbiology, Department of Pathobiology, School of Public Health, Tehran University of Medical Sciences, Food Microbiology Research Center, Tehran University of Medical Sciences, Tehran, Iran.
Insights
Aeromonas species are a significant cause of diarrhea in children. This study found increasing antimicrobial resistance, particularly to trimethoprim-sulfamethoxazole and nalidixic acid, highlighting the need for vigilant identification and susceptibility testing.
Area of Science:
- Microbiology
- Infectious Diseases
- Pediatrics
Background:
- Aeromonas species are common causes of intestinal and extraintestinal diseases, frequently isolated from young children.
- Diarrhea in children under five years old is often associated with Aeromonas spp. infections.
Purpose of the Study:
- To determine the prevalence of Aeromonas species in children with diarrhea.
- To analyze the antimicrobial resistance patterns of isolated Aeromonas strains.
- To investigate the presence of key virulence genes in these isolates.
Main Methods:
- Collected 391 stool samples from children aged 1 day to 14 years with diarrhea.
- Utilized alkaline peptone water enrichment and biochemical tests for Aeromonas identification.
- Performed antimicrobial susceptibility testing and polymerase chain reaction for virulence genes (act, ast, alt, aerA, hlyA).
Main Results:
- Identified 12 Aeromonas isolates (3.1%), including A. caviae, A. veronii, and A. hydrophila.
- High antimicrobial resistance observed against nalidixic acid and trimethoprim-sulfamethoxazole (41.6%).
- Prevalence of virulence genes: aerA (83.3%), alt (71.5%), ast (64.7%), act (76.4%), and hlyA (11.7%).
Conclusions:
- Aeromonas spp. are significant fecal pathogens causing childhood diarrhea, necessitating laboratory identification.
- Virulence genes are linked to severe gastroenteritis, and their presence warrants attention.
- Increasing antimicrobial resistance, especially to trimethoprim-sulfamethoxazole and nalidixic acid, is a growing concern.
Background:
Aeromonas spp. cause various intestinal and extraintestinal diseases. These bacteria are usually isolated from fecal samples, especially in children under five years old. The aim of this study was to assess the prevalence of Aeromonas spp. and their antimicrobial resistance profile in children with diarrhea referred to the Children Medical Center in Tehran, between 2013 and 2014.
Methods:
A total number of 391 stool samples were collected from children with ages between 1 day and 14 years old, with diarrhea (acute or chronic), referred to the Children Hospital, Tehran, Iran, between 2013 and 2014. Samples were enriched in alkaline peptone water broth for 24 hours at 37 °C and then cultured. Suspicious colonies were analyzed through biochemical tests. Furthermore, antimicrobial susceptibility tests were carried out for the isolates. Isolates were further studied for act, ast, alt, aerA and hlyA virulence genes using polymerase chain reaction.
Results:
In total, 12 isolates (3.1%) were identified as Aeromonas spp.; all were confirmed using the API-20E test. Of these isolates, five A. caviae (42%), four A. veronii (33%) and three A. hydrophila (25%) were identified in cases with gastroenteritis. Second to ampicillin (which was included in the growth medium used), the highest rate of antimicrobial resistance was seen against nalidixic acid and trimethoprim-sulfamethoxazole (5 isolates each, 41.6%) and the lowest rate of antimicrobial resistance was seen against gentamicin, amikacin and cefepime (none of the isolates). Results included 76.4% act, 64.7% ast, 71.5% alt, 83.3% aerA and 11.7% hlyA genes.
Conclusion:
Aeromonas spp. are important due to their role in diarrhea in children; therefore, isolation and identification of these fecal pathogens should seriously be considered in medical laboratories. Since virulence genes play a significant role in gastroenteritis symptoms caused by these bacteria, Aeromonas species that include virulence genes are potentially suspected to cause severe infections. Moreover, bacterial antimicrobial resistance is increasing, especially against trimethoprim-sulfamethoxazole and nalidixic acid.
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