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GENTAMICIN‐RESISTANT STAPHYLOCOCCUS AUREUS STRAINS AND THEIR SUSCEPTIBILITY TO OTHER AMINOGLYCOSIDES
Author(s) -
BANG JØRGEN,
ROSDAHL VIBEKE T.,
BENTZON MICHAEL WEIS,
ROSENDAL KIRSTEN
Publication year - 1982
Publication title -
acta pathologica microbiologica scandinavica series b: microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.909
H-Index - 88
eISSN - 1600-0463
pISSN - 0108-0180
DOI - 10.1111/j.1699-0463.1982.tb00132.x
Subject(s) - amikacin , gentamicin , kanamycin , netilmicin , staphylococcus aureus , tobramycin , microbiology and biotechnology , sisomicin , streptomycin , chemistry , biology , veterinary medicine , antibiotics , medicine , bacteria , genetics
Forty‐six Staphylococcus aureus strains with an IC‐50 value to gentamicin (G) of 1 μg/ml or more were investigated for their IC‐50 values to kanamycin (K), tobramycin (To), sisomicin (Si), streptomycin (S), netilmicin (Net) and amikacin (Ami). Correlation coefficients greater than 0.98 were found between the values of G and those of K, To, Si, Net and Ami, whereas a negative correlation was found between those of G and S. As the break‐points between susceptible and resistant strains were defined as 1 μ/ml to G, To and Si, 2 μ/ml to Net, 2.5 μ/ml to K and Ami and 3 μ/ml to S, all the 46 strains were also resistant to K, To and Si. A total of 15 strains were resistant to Net, 30 to Ami and 18 to S. All the strains were examined for their susceptibility to the seven aminoglycosides by three disc‐diffusion methods: the 20‐hours' pre‐diffusion method, the Biodisk paper‐disc method and Rosco Neo‐sensitabs. Satisfactory agreement was found between the IC‐50 values and the placing into four susceptibility groups by these three methods, when susceptibility to G, K, To, Si and S was investigated. The three disc‐diffusion methods evaluated susceptibility to Net identically with the majority of strains ‐ susceptible as well as resistant ‐ in group 2, but susceptibility to Ami was estimated differently by the three methods. The problems may be caused by the differences in the break‐points chosen and influenced by the »clustering« of the various zone diameters around the breakpoints. For Net and Ami a better correlation between the MIC/IC‐50 values and the groups of susceptibility obtained by the disc‐diffusion methods is needed.