Growth temperature-dependent variation of cell envelope lipids and antibiotic susceptibility in Stenotrophomonas (Xanthomonas) maltophilia

• Published in: Journal of antimicrobial chemotherapy 1995-08, Vol.36 (2), p.317-326
• Main Authors: Rahmati-Bahram, A., Magee, J. T., Jackson, S. K.
• Format: Article
• Language: English
• Subjects: Anti-Bacterial Agents - pharmacology; Anti-Infective Agents, Local - pharmacology; Antibacterial agents; Antibiotics. Antiinfectious agents. Antiparasitic agents; Bacterial Outer Membrane Proteins - metabolism; Biological and medical sciences; Cytoplasm - drug effects; Cytoplasm - metabolism; Electron Spin Resonance Spectroscopy; Fatty Acids - metabolism; Humans; Medical sciences; Membrane Fluidity - drug effects; Membranes - drug effects; Membranes - metabolism; Pharmacology. Drug treatments; Phenylethyl Alcohol - pharmacology; Spin Labels; Temperature; Xanthomatosis - microbiology; Xanthomonas - drug effects; Xanthomonas - growth & development; Xanthomonas - ultrastructure
• ISSN: 0305-7453; 1460-2091
• DOI: 10.1093/jac/36.2.317

Clinical isolates of Stenotrophomonas (Xanthomonas) maltophilia showed growth temperature-dependent variation in susceptibility (TDVS) to aminoglycoside antibiotics between 30°C and 37°C, but little or no TDVS effect for polymixin B, colistin, ceftazidime, chloramphenicol and piperacillin. When phenylethanol was added at sub-inhibitory concentrations, the TDVS effect was eliminated. Gas liquid chromatography showed that 13-methyl tetradecanoate (i-15; 0), was the predominant fatty acid, and was present in lower proportions in cells grown at 30°C than 37°C, by contrast to the unsaturated acids, which were found in increased proportions in cells grown at 30°C. However, the extent of these shifts in composition did not correlate with the extent of the TDVS effect in individual strains. Membrane analysis by spin label-electron spin resonance spectroscopy showed that strains exhibiting TDVS had significantly decreased membrane fluidity compared with susceptible strains at 30°C. Furthermore, analysis of the outer and cytoplasmic membranes from the strains with TDVS revealed that in organisms grown at 30°C, the outer membrane remained in a more rigid conformation than the cytoplasmic membrane. We conclude that resistance of S. maltophilia to aminoglycoside antibiotics at 30°C correlates with changes in the conformation of the outer membrane so that binding and/or uptake of the antibiotic is inhibited.