Summary. The development of non-specific resistance to gentamicin, tobramycin and amikacin was studied in 12 clinical isolates of entero-bacteria with various patterns of aminoglycoside resistance. Strains were characterised with respect to MIC, transferability of resistance and possession of acetylating and adenylylating enzymes.

An increase in aminoglycoside resistance was induced in 10 strains by a single exposure to the concentration of gentamicin, tobramycin or amikacin immediately below the MIC. Such resistance was non-specific; all three aminoglycosides were affected irrespective of which one had been used to induce the increase. Increments in non-specific aminoglycoside resistance were also evoked by exposure of enterobacteria to changing drug concentrations similar to those achieved in plasma during therapy. When strains already resistant to gentamicin or other aminoglycosides were exposed to therapeutically achievable drug concentrations, no further increase in resistance was observed in most cases. This suggests that use of an aminoglycoside to which the organism is resistant, as during ‘blind’ therapy, will not usually compromise subsequent treatment with related antibiotics. The possible relevance of non-specific aminoglycoside resistance to therapy is discussed.


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