Abstract
Of 422 clinical strains of Pseudomonas aeruginosa, 23 (5.5%) were resistant to gentamicin; 19 were also resistant to tobramycin and sisomycin, and one was resistant to tobramycin, sisomycin and amikacin. Of the gentamicin-resistant strains, 20 were also resistant to kanamycin. Sixteen strains with a high level of resistance to gentamicin (MIC greater than 160 microgram/ml) transferred all their resistance determinants to recipient strains of P. aeruginosa and four transferred some resistance determinants to P. aeruginosa but none transferred resistance to a recipient strain of E. coli K12. These results show that gentamicin resistance in strains of P. aeruginosa isolated in Auckland is mediated by R plasmids.