title: Characterization of cell membrane parameters of clinical isolates of Staphylococcus aureus with varied susceptibility to alpha-melanocyte stimulating hormone.
abstract: Staphylococcus aureus (S. aureus), a major human pathogen of hospital and community acquired infections, is becoming resistant to almost all commercially available antibiotics. This has prompted development of antimicrobial peptides as therapeutic options. Alpha melanocyte stimulating hormone (α-MSH) is one such peptide known to possess antimicrobial properties. In the present study, we analyzed the antimicrobial activity of α-MSH against 75 clinical strains of S. aureus including both methicillin susceptible S. aureus (MSSA) and methicillin resistant S. aureus (MRSA) strains. Results of our previous study showed that membrane damage is the major mechanism of staphylocidal activity of α-MSH. In this context, we compared the various bacterial membrane parameters, viz., membrane fluidity, lipid composition, and surface charge of a few selected MSSA and MRSA strains that showed variable susceptibility to the melanocortin peptide. Our results showed that α-MSH killed both type of strains efficiently (≥ 70% killing in 84% clinical strains after exposure with 6 μM of α-MSH for 1h). It was observed that compared to the α-MSH-susceptible strains, the α-MSH-non-susceptible strains had a different membrane order and phospholipid pattern. There was no consistent pattern of cell surface charge to distinguish α-MSH-susceptible strain from a non-susceptible strain. In conclusion, α-MSH possessed potential staphylocidal activity for both against MSSA and MRSA strains. S. aureus strains not susceptible to the peptide exhibited a rigid membrane and a higher amount of the cationic phospholipid as compared to the α-MSH-susceptible strains.
authors: School of Environmental Sciences, Jawaharlal Nehru University, New Delhi 110067, India.
authors: Tahsina
authors: T
authors: Shireen
authors: Madhuri
authors: M
authors: Singh
authors: Benu
authors: B
authors: Dhawan
authors: Kasturi
authors: K
authors: Mukhopadhyay
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002462:Cell Membrane / Q000187:drug effects*; D008560:Membrane Fluidity / Q000187:drug effects; D008826:Microbial Sensitivity Tests; D013211:Staphylococcus aureus / Q000166:cytology* / Q000187:drug effects*; D000521:alpha-MSH / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D000521:alpha-MSH