Fatty acid analysis ofStenotrophomonas maltophilia clinical strains showing different susceptibility to antibiotics at 30 and 37°C

Isolates ofStenotrophomonas maltophilia species display the feature “temperature-dependent susceptibility” (TDS) to antibiotics. Both 30TDS strains (at least 4 times lower value of minimum inhibitory concentration (MIC) of an antibiotic at 30 than at 37°C) and 37TDS strains (at least 4 times lower value of MIC at 37 than at 30°C) were described. Changes in the distribution of saturated and unsaturated fatty acids (FA) at 30 and 37°C were considered as one of possible causes of the TDS phenomenon. Gas chromatography was used to determine the distribution of individual FA in five 37TDS strains ofS. maltophilia (Group I); in five strains with MIC values unaffected by the cultivation temperature (Group II) and in six 30TDS (four strains) or 30/37TDS (two strains) isolates (Group III). At identical temperatures, no statistically significant differences in the distribution of major FA (iso-15:0,anteiso-15:0, 16:0 and 16:1) were registered between individual groups. Statistically significant (p<0.05) differences between groups were found in minor FA only (iso-16:0,iso-17:0 andiso-17:1). Distribution changes of cellular FA at 30 and 37°C can be considered to play only a minor role in the formation of the TDS phenomenon.