apramycin and Cross-Infection

Apramycin is a recently developed aminoglycoside restricted to veterinary therapy. Production of a 3-aminoglycoside acetyltransferase type IV (AAC(3)-IV) conferring cross-resistance to this drug and to gentamicin was detected in 1984 in France in bacteria of bovine origin. This mechanism of resistance was apparently confined to animals. We have studied 17 strains resistant to apramycin and gentamicin isolated in 5 hospitals in Belgium. Conjugative plasmids encoding an AAC(3)IV were present in 14 isolates. Comparison of the restriction fingerprints revealed 6 different plasmid patterns: 8 plasmids belonged to 2 groups sharing extensive intragroup homology and 4 were not related to the other replicons. These results indicate dissemination of plasmids within and between hospitals, but also of the gene encoding an AAC(3)IV.

Topics: Animals; Anti-Bacterial Agents; Cattle; Cross Infection; DNA Probes; Drug Resistance, Microbial; Enterobacteriaceae; Enterobacteriaceae Infections; Humans; Nebramycin; Nucleic Acid Hybridization; R Factors; Replicon; Transfection

Apramycin-modifying strains isolated from pigs with coli bacteriosis, from humans and hospital environment were studied comparatively. Production of enzymes modifying the aminoglycoside was estimated with the radioactive cofactor procedure. E. coli isolates from the animals were phenotypically resistant to apramycin and a number of other aminoglycosides. They produced acetyltransferase AAC(3)IV, phosphotransferase APH(3')(5"), APH(3") and other enzymes. Resistance of the strains to gentamicin was also conditioned by AAC(3)IV since these strains did not produce AAD(2") and AAC(6'). In the resistant strains of E. coli and their transconjugates there were detected plasmids with a relative molecular weight of 60-80 MD. Some of the belonged to the compatibility group I1, the others belonged to the compatibility group H1. Strains of S. marcescens, K. pneumoniae. K. oxytoca and S. aureus isolated from humans and hospital environment were sensitive to apramycin. Only isolates of P. aeruginosa were resistant to this antibiotic. However, all the isolates produced AAC(3)IV. Some of them additionally produced AAC(6'), an enzyme modifying amikacin, kanamycin and other antibiotics and not acetylating apramycin. Almost all the strains produced kanamycin- and streptomycin phosphotransferases. Possible coselection of strains resistant to apramycin and gentamicin using one of these aminoglycosides is discussed.

Topics: Animals; Anti-Bacterial Agents; Bacteria; Cross Infection; Drug Resistance, Microbial; Environmental Microbiology; Escherichia coli Infections; Humans; Microbial Sensitivity Tests; Nebramycin; Swine; Swine Diseases