Duplex PCR assay for simultaneous detection of two aminoglycoside resistance genes in clinical samples of enterobacteriaceae

Theo, Chun Hao (2022) Duplex PCR assay for simultaneous detection of two aminoglycoside resistance genes in clinical samples of enterobacteriaceae. Final Year Project, UTAR.

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Abstract

Aminoglycosides include semi-synthetic and natural antibiotics isolated from Actinomycetes. They are well-known for their efficacy against the Enterobacteriaceae family. Nevertheless, the mass prescription of aminoglycosides in clinical settings has resulted in a significant rise in the number of aminoglycoside-resistant Enterobacteriaceae due to the presence of different resistance genes that synthesise aminoglycoside-modifying enzymes. In this study, a total of 60 clinical isolates of Enterobacteriaceae obtained from different hospitals in West Malaysia were subjected to eight antibiotics. Subsequently, the bacterial isolates were screened for the presence of ant(2’’)-Ia and aph(3’)-Ic genes simultaneously using duplex PCR. Twenty-three (38.33%) isolates of the 60 bacterial isolates were tested positive for ant(2’’)-Ia, 13 (21.67%) were tested positive for aph(3’)-Ic and only one (1.67%) bacterial isolate was tested positive for both ant(2’’)-Ic and aph(3’)-Ic genes. The prevalence of ant(2’’)-Ia and aph(3’)-Ic in Enterobacteriaceae was 40.00% and 23.33%, respectively. The ant(2’’)-Ia gene was more prevalent in Enterobacteriaceae as compared to the aph(3’)-Ic gene. Besides, E. coli and K. pneumoniae were found to host at least one aminoglycoside resistance gene. Statistical analysis determined that there were significant associations between the ant(2’’)-Ia gene with gentamicin, kanamycin, and imipenem resistance, and the aph(3’)-Ic gene with kanamycin resistance. However, the association between ant(2’’)-Ia gene with imipenem resistance may be caused by coincidence, in which the bacterial isolates hosting the ant(2’’)-Ia gene were carrying other imipenem resistance genes concurrently. This is because aminoglycoside resistance genes were proven to confer cross-resistance only within aminoglycosides, instead of other classes of antibiotics. Nonetheless, the age and gender of the patients have no statistically significant association with the resistance genes studied.

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