Prognostic parameters of the susceptibility of staphylococcus spp. to aminoglycosides and doxycycline

Abstract

The aim: To perform microbiological investigation and analytic mathematic prediction of clinical isolates of S. aureus to aminoglycosides in patients with severe burns. Materials and methods: We analyzed resistance of 199 S. aureus strains to aminoglycosides (gentamicin, tobramycin and amikacin) and doxycycline from 435 patients treated in the regional hospital due to burns for the period from 2011-2017. Results: We created predictive curves for the prediction of susceptibility of S. aureus strains to aminoglycosides and doxycycline based on the changes in S. aureus resistance during the years of observation and expressed in mathematic equations. Susceptibility of S. aureus to gentamicin was 42.86 % at the end of observation and will decline in future. Despite tobramycin was efficient against 72.86 % of strains in 2017, mathematic modeling indicates rapid decline in its efficacy in future. Efficacy of amikacin was dropping during the last years, but according to the equation it efficacy will increase over 60 % in 2018. S. aureus susceptibility to doxycycline was 65.38 % in 2017 and mathematic modeling indicates its gradual decline in the nearest future. Conclusions:PredicitivevaluesofS. aureus susceptibility indicates not sufficient efficacy of these drugs in patients with infectious complications of burns. Tendency of the slight decline of S. aureus susceptibility to doxycycline still indicates sufficient levels of its efficacy in the nearest future. This justify its use as a second-line therapy with the causative agent in patients with burns.