Aminoglycoside resistance in Haemophilus influenzae

From September 1, 1990 to December 31, 1993 a total of 425 Haemophilus influenzae strains from clinical specimens were isolated in the Microbiology Laboratory of the Zaragoza University Hospital. Of these strains, 16 (33.33%) were resistant to kanamycin, neomycin, paromomycin, lividomycin and streptomycin. Demonstration of APH (3')-I activity by the phosphocellulose paper binding assay, based on the incorporation of radiolabel into lividomycin was sixfold greater than into butirosin. Two DNA probes were prepared to screen for the genes encoding APH(3') activity in kanamycin-resistant H. influenzae. Homology was observed between the aphA1 DNA probe and total cellular DNA from all 16 APH(3')-I producers. On the other hand, streptomycin-resistance was not through metabolic modification of the antibiotic.