Influence of Exogenous Factors and Antibiotics on the Cytoplasmic Membrane Proteins of <i>Staphylococcus aureus</i>

Abstract

The influence of various nutrient media, growth temperature, phase of growth and subinhibitory concentrations of antibiotics from various groups on the cytoplasmic membrane proteins was studied in 6 clinical S. aureus isolates; further study included the comparison of the cytoplasmic membrane proteins in antibiotic-sensitive wild-type (parent) strains with their resistant counterparts. Resistant clones could be selected with a frequency ranging from 10^-7 to 10^-8 from the parent strain at twice the MIC. The following was observed from the study of six clinical isolates: (a) there was no uniform pattern of cytoplasmic membrane proteins among the isolates; (b) during the phase of growth, the number of high-molecular-weight proteins showed a decrease according to the duration of growth; (c) the addition of 1% w/v glucose to the growth medium resulted in the loss of an approximately 75 kD protein in five of the six strains; (d) subinhibitory concentrations of various antibiotics (1/4 of the MIC) resulted in major changes of cytoplasmic membrane proteins, when the strains were exposed to oxacillin, whereas this was not the case for erythromycin, rifampicin, gentamicin, trimethoprim, fleroxacin and vancomycin; (e) the resistant clones differed from their sensitive parent strains in their cytoplasmic membrane protein patterns. The alterations were not characteristic either for the strain or for the antibiotic considered, thus suggesting an ‘unspecific’ defense mechanism characterized by individual changes of the cytoplasmic membrane proteins.

Bacterial Response to the Surface Aging of PLA Matrices Loaded with Active Compounds

“…The interaction of CTAB with the bacterial membrane affects its viability, as do the pH and osmolarity of the medium, starvation, extreme temperatures, oxygen concentration, amount of glucose, bactericidal agents or the bacterial metabolic state itself [52][53][54][55]. In particular, in the study by Sathya et al [56], the effects of CTAB nanocomposites on the bacterial surface structure were investigated using strains with different surface properties.…”