Administration of either gentamicin or amikacin induced an increase in the number of amikacin-resistant (AR) isolates of certain Enterobacteriaceae and species in a hospital in Buenos Aires. A total of 127 AR isolates was selected to study the molecular mechanisms of resistance involved. The gene was found by dot-blot hybridisation in every isolate. A gene different from and encoding the AAC(6′)-I activity was found in a 15-5-kb plasmid in spp. Plasmids from 27 Enterobacteriaceae contained an gene and 26 of these carried sequences related to the Tn1331 transposon, whereas one plasmid showed homology in another fragment of the Tn1331 transposase. Because plasmids bearing the gene were heterogeneous, dissemination of the gene may have been due to transposition of Tn1331 rather than the spread of an epidemic plasmid. The rate of AR isolates varied within each species in spite of the presence of Tn1331, and it is likely, therefore, that this transposon may not be the sole factor responsible for the observed variation. The aph(3′)-VIa gene (originally described in spp.) was found with high frequency (80%) in this population. Furthermore, this gene was found also in plasmids from 20% of other gram-negative organisms commonly involved in nosocomial infections in this hospital.


Article metrics loading...

Loading full text...

Full text loading...


Most cited this month Most Cited RSS feed

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error