Aminoglycoside-resistance mechanisms in multidrug-resistant Staphylococcus aureus clinical isolates.
Aminoglycoside resistance in six clinically isolated Staphylococcus aureus was evaluated. Genotypical examination revealed that three isolates (HLGR-10, HLGR-12, and MSSA-21) have aminoglycoside-modifying enzyme (AME) coding genes and another three (GRSA-2, GRSA-4, and GRSA-6) lacked these genes in their genome. Whereas isolates HLGR-10 and HLGR-14 possessed bifunctional AME coding gene aac(6')-aph(2''), and aph(3')-III and showed high-level resistance to gentamycin and streptomycin, MSSA-21 possessed aph(3')-III and exhibited low resistance to gentamycin, streptomycin, and kanamycin. The remaining three isolates (GRSA-2, GRSA-4, and GRSA-6) exhibited low resistance to all the aminoglycosides because they lack aminoglycoside-modifying enzyme coding genes in their genome. The transmission electron microscopy of the three isolates revealed changes in cell size, shape, and septa formation, supporting the view that the phenomenon of adaptive resistance is operative in these isolates.
Chandrakanth
R Kelmani
RK
Department of Biotechnology, Gulbarga University, Gulbarga, 585 106, Karnataka, India. ckelmani@gmail.com
Raju
S
S
Patil
S A
SA
D000617:Aminoglycosides / Q000494:pharmacology*; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D016172:DNA Fingerprinting; D052978:Disk Diffusion Antimicrobial Tests; D024881:Drug Resistance, Bacterial; D005838:Genotype; D006801:Humans; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D013203:Staphylococcal Infections / Q000382:microbiology*; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification* / Q000648:ultrastructure
D000617:Aminoglycosides; D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins