Small changes in environmental parameters lead to alterations in antibiotic resistance, cell morphology and membrane fatty acid composition in Staphylococcus lugdunensis.
Staphylococcus lugdunensis has emerged as a major cause of community-acquired and nosocomial infections. This bacterium can rapidly adapt to changing environmental conditions to survive and capitalize on opportunities to colonize and infect through wound surfaces. It was proposed that S. lugdunensis would have underlying alterations in metabolic homeostasis to provide the necessary levels of adaptive protection. The aims of this project were to examine the impacts of subtle variations in environmental conditions on growth characteristics, cell size and membrane fatty acid composition in S. lugdunensis. Liquid broth cultures of S. lugdunensis were grown under varying combinations of pH (6-8), temperature (35-39°C) and osmotic pressure (0-5% sodium chloride w/w) to reflect potential ranges of conditions encountered during transition from skin surfaces to invasion of wound sites. The cells were harvested at the mid-exponential phase of growth and assessed for antibiotic minimal inhibitory concentration (MIC), generation time, formation of small colony variants, cell size (by scanning electron microscopy) and membrane fatty acid composition. Stress regimes with elevated NaCl concentrations resulted in significantly higher antibiotic resistance (MIC) and three of the combinations with 5% NaCl had increased generation times (P<0.05). It was found that all ten experimental growth regimes, including the control and centroid cultures, yielded significantly different profiles of plasma membrane fatty acid composition (P<0.0001). Alterations in cell size (P<0.01) were also observed under the range of conditions with the most substantial reduction occurring when cells were grown at 39°C, pH 8 (514±52 nm, mean ± Standard Deviation) compared with cells grown under control conditions at 37°C with pH 7 (702±76 nm, P<0.01). It was concluded that S. lugdunensis responded to slight changes in environmental conditions by altering plasma membrane fatty acid composition, growth rates and morphology to achieve optimal adaptations for survival in changing environments.
Metabolic Research Group, School of Environmental and Life Sciences, The University of Newcastle, Callaghan, Australia.
Marcus J
MJ
Crompton
Metabolic Research Group, School of Environmental and Life Sciences, The University of Newcastle, Callaghan, Australia.
R Hugh
RH
Dunstan
Metabolic Research Group, School of Environmental and Life Sciences, The University of Newcastle, Callaghan, Australia.
Margaret M
MM
Macdonald
Department of Chemistry, Gothenburg University, Göteborg, Sweden.
Johan
J
Gottfries
Institute of Medical Microbiology, University of Münster, Münster, Germany.
Christof
C
von Eiff
Metabolic Research Group, School of Environmental and Life Sciences, The University of Newcastle, Callaghan, Australia.
Timothy K
TK
Roberts
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D004352:Drug Resistance, Microbial; D005227:Fatty Acids / Q000378:metabolism*; D005839:Gentamicins / Q000494:pharmacology*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D009997:Osmotic Pressure; D013203:Staphylococcal Infections / Q000188:drug therapy / Q000382:microbiology; D057787:Staphylococcus lugdunensis / Q000166:cytology / Q000187:drug effects* / Q000502:physiology*; D013696:Temperature
D000900:Anti-Bacterial Agents; D005227:Fatty Acids; D005839:Gentamicins