Abstract:
Aminoglycoside resistance through the production of aminoglycoside modifying enzymes (AMEs) is common and
thus of clinical importance. The presence of AMEs genes in gram-negative bacteria on plasmids, transposons and
integrons facilitates the rapid acquisition of antibiotic resistance. This study aimed to characterize AMEs in
antibiotic resistant strains of Escherichia, Klebsiella, Pseudomonas and Acinetobacter implicated in invasive
infections in Nairobi, Kenya. The experimental design was a two point cross-sectional design comparing 54 clinical
isolates obtained from the KEMRI laboratory collected in 2001 to 2006 and 54 clinical isolates from Aga Khan
University Hospital collected in 2007 to 2008. The isolates were identified, tested for antimicrobial susceptibility to
seven aminoglycosides then the AMEs were detected phenotypically and genotypically. The most prevalent AME
gene detected was acc(6)-Ib-cr (45.9%) followed by acc(3)-II (25.9%, aac(6)-I(22.2%) and aac(3)-I (16.3%).
Phenotypic studies showed that multidrug resistant Pseudomonas aeruginosa harboured numerous AMEs and 81%
of the resistance was conferred by impermeability. Increase in aminoglycoside resistance by both naturally
derived and semi synthetic antibiotics is alarming. Methods for monitoring their effectiveness should be instituted
at the different healthcare system in Kenya.
