| The purpose of the current study was to evaluate the phenotypic and genotypic patterns of aminoglycoside resistance among the Gram-negative bacteria (GNB) isolates collected from pediatric and general hospitals in Iran. A total
of 836 clinical isolates of GNB were collected from pediatric and general hospitals from January 2018 to the end of
December 2019. The identifcation of bacterial isolates was performed by conventional biochemical tests. Susceptibility to aminoglycosides was evaluated by the disk difusion method (DDM). The frequency of genes encoding aminoglycoside-modifying enzymes (AMEs) was screened by the PCR method via specifc primers. Among all pediatric
and general hospitals, the predominant GNB isolates were Acinetobacter spp. (n = 327) and Escherichia coli (n = 144).
However, E. coli (n = 20/144; 13.9%) had the highest frequency in clinical samples collected from pediatrics. The DDM
results showed that 64.3% of all GNB were resistant to all of the tested aminoglycoside agents. Acinetobacter spp. and
Klebsiella pneumoniae with 93.6%, Pseudomonas aeruginosa with 93.4%, and Enterobacter spp. with 86.5% exhibited
very high levels of resistance to gentamicin. Amikacin was the most efective antibiotic against E. coli isolates. In total,
the results showed that the aac (6’)-Ib gene with 59% had the highest frequency among genes encoding AMEs in
GNB. The frequency of the surveyed aminoglycoside-modifying enzyme genes among all GNB was found as follows:
aph (3’)-VIe (48.7%), aadA15 (38.6%), aph (3’)-Ia (31.3%), aph (3’)-II (14.4%), and aph (6) (2.6%). The obtained data demonstrated that the phenotypic and genotypic aminoglycoside resistance among GNB was quite high and it is possible
that the resistance genes may frequently spread among clinical isolates of GNB |