Prevalence, virulence and antimicrobial resistance patterns of Aeromonas spp. isolated from children with diarrhea.
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.


CONCLUSIONS
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.
PhD, 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.
Mohammad Mehdi
MM
Soltan Dallal
PhD, Division of Food Microbiology, Department of Pathobiology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.
Ramin
R
Mazaheri Nezhad Fard
MSc, Division of Medical Bacteriology, Department of Pathobiology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.
Morteza
M
Kavan Talkhabi
DVM, Professional Doctorate Student in Veterinary Medicine, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran.
Leyla
L
Aghaiyan
PhD of Medical Immunology, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran.
Zohre
Z
Salehipour
Aeromonas spp; Iran; antimicrobial resistance; children; diarrhea