Evaluation of Phenotypic and Genotypic Patterns of Aminoglycoside Resistance among Certain Multidrug-Resistant Gram-Negative Bacterial Isolates Collected from Different Egyptian Hospitals

The aim of the current study was to assess the genotypic and phenotypic patterns of aminoglycoside resistance among the Gram-negative bacteria (GNB) isolates collected from various Egyptian hospitals. A total of 195 clinical isolates of GNB were collected from four different hospitals in Cairo from November 2017 to the end of October 2018. The identification of bacterial isolates was carried out by conventional biochemical tests and VITEK® 2 system. Susceptibility to aminoglycosides was examined by the disk diffusion method (DDM). The prevalence of genes encoding aminoglycoside modifying enzymes (AMEs) was screened by the PCR method via particular primers. The frequency of the isolates was: K. pneumoniae (n = 86/195; 44.1%), P. aeruginosa (n = 48/195; 24.6%), Acinetobacter spp. (n = 28/195; 14.3%), and E. coli (n = 24/195; 12.3%). The DDM results showed that 73.2% of all tested isolates were resistant to all tested aminoglycosides. The frequency of the screened aminoglycoside resistance genes among tested isolates was found as follows: aac (6')-Ib (100%), aph(3΄)-VI (45.8%), aadA (25%), aac(3)-Ia (16.6%), ant(2΄΄)-I (16.6%). In conclusion, there is a significant degree of aminoglycoside resistance among GNB and it is probable that the resistance genes may frequently be transmitted between clinical isolates of GNB.