species can cause a wide spectrum of illnesses varying from intestinal to extra intestinal
and vary in their susceptibility to different antibiotics. The current study was undertaken to characterize the third
generation cephalosporin-resistant strains of Aeromonas
spp. which were isolated from stool specimens.
Out of a total of 2780 stool samples, 29 Aeromonas
spp. were identified, out of which, 9 were resistant
to ceftriaxone by the Kirby-Bauer antibiotic testing method. These strains were subjected to minimum inhibitory
concentration (MIC) determination by agar dilution for ceftriaxone. Phenotypic and genotypic testing of AmpC
beta-lactamase and extended spectrum beta-lactamase (ESBL) were performed. Gene transfer was carried out to
demonstrate transmissibility of these genetic elements by conjugation experiments.
Out of the 29 strains, 9 showed MIC of ≥4 μg/ml. Seven out of 9 showed presence of blaCTX-M, while 2
more strains showed the presence of inducible AmpC beta-lactamase and presence of MOX gene. Gene transfer
experiments showed that these elements were transmissible to recipient (
J53 strain) in the presence
Dissemination of these resistance determinants like plasmids is pivotal in the spread of these
resistance genes into the aquatic environment into organisms like Aeromonas
. This may further limit the future
use of antibiotics for the treatment of diarrhoeal diseases. Hence, detection and antibiotic susceptibility testing
spp. should be performed when isolated from stool samples.