Presence of acetyl-transferases and adenylyl-transferases in gentamicin-resistant transconjugants.
The aim of this work was to test the production of aminoglycoside modifying enzymes in 20 gentamicin-resistant transconjugants obtained from clinical strains of Entero-bacteriaceae. The susceptibility to aminoglycosides was determined by disc diffusion method and agar dilution method according to European Committee for Clinical Laboratory Standards, 1988. The transfer of gentamicin-resistance R-plasmids was made by conjugation on a solid medium with recipients E. coli K12. Phosphocellulose paper binding assay with 14C acetyl. CoA and 14C.ATP by Haas and Dowding was performed to reveal the enzyme production. Four different acetyl-transferases have been found: AAC/3/I, AAC/3/-V, AAC/3/-IV which modify gentamicin, and AAC/6'/-I with activity on amikacin. Only two of the transconjugants showed adenylyl-transferase activity:AAD/2"/. Some of strains tested possessed two enzymes. The most interesting finding was that the majority of strains owned AAC/3/-IV, which modifies apramycin. This was be explained with the fact that apramycin is still in a large use for animal husbandry in Bulgaria.


CONCLUSIONS
four different acetyl-transferases: AAC/3/-I, AAC/3/-V, AAC/3/-IV and AAC/6'/-I and the adenylyl-transferase AAD/2"/ were found to be the biochemical mechanisms of resistance to aminoglycosides in 20 gentamicin-resistant transconjugants.
Keuleyan
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Département de Microbiologie, Académie de Médecine de Sofia, Bulgarie.
D000101:Acetyl-CoA C-Acetyltransferase / Q000032:analysis* / Q000378:metabolism; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D004352:Drug Resistance, Microbial; D004755:Enterobacteriaceae / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D004926:Escherichia coli / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D005839:Gentamicins / Q000494:pharmacology*; D066298:In Vitro Techniques; D009612:Nicotinamide-Nucleotide Adenylyltransferase / Q000032:analysis* / Q000378:metabolism; D014162:Transfection / Q000502:physiology
D000900:Anti-Bacterial Agents; D005839:Gentamicins; D000101:Acetyl-CoA C-Acetyltransferase; D009612:Nicotinamide-Nucleotide Adenylyltransferase