Abstract
Staphylococcus pseudintermedius is a common commensal bacterium colonizing the skin and mucosal surfaces of household animals. However, it has recently emerged as a dangerous opportunistic pathogen, comparable to S. aureus for humans. The epidemiological situation is further complicated by the increasing number of methicillin-resistant S. pseudintermedius infections and evidence of gene transmission driving antibiotic resistance between staphylococci colonizing human and zoonotic hosts. In the present study, we describe a unique peptide, BacSp222, that possesses features characteristic of both bacteriocins and virulence factors. BacSp222 is secreted in high quantities by S. pseudintermedius strain 222 isolated from dog skin lesions. This linear, fifty-amino-acid highly cationic peptide is plasmid-encoded and does not exhibit significant sequence similarities to any other known peptides or proteins. BacSp222 kills gram-positive bacteria (at doses ranging from 0.1 to several micromol/l) but also demonstrates significant cytotoxic activities towards eukaryotic cells at slightly higher concentrations. Moreover, at nanomolar concentrations, the peptide also possesses modulatory properties, efficiently enhancing interferon gamma-induced nitric oxide release in murine macrophage-like cell lines. BacSp222 appears to be one of the first examples of multifunctional peptides that breaks the convention of splitting bacteriocins and virulence factors into two unrelated groups.
Highlights
Staphylococcus pseudintermedius is a common commensal bacterium colonizing the skin and mucosal surfaces of household animals
We have established a method based on the restriction fragment length polymorphism (RFLP) technique, which allows the determination of the Staphylococcus species within the Staphylococcus intermedius group (SIG)[6]
Our attention was focused on S. pseudintermedius strain 222, which was isolated from skin lesions in a dog; this bacteria was found to produce an agent inhibiting the growth of methicillin-resistant S. aureus (MRSA) strain USA300
Summary
Staphylococcus pseudintermedius is a common commensal bacterium colonizing the skin and mucosal surfaces of household animals. This task is commonly attributed to bacteriocins, which are ribosomally synthesized peptides or proteins that are able to kill closely related bacteria[18] Both types of staphylococci, namely those considered to be exclusively commensal and those that are opportunistic pathogens, were demonstrated to produce bacteriocins, which indicates their importance in maintaining the microbiome of the skin and mucosal surfaces[19,20,21]. Namely those considered to be exclusively commensal and those that are opportunistic pathogens, were demonstrated to produce bacteriocins, which indicates their importance in maintaining the microbiome of the skin and mucosal surfaces[19,20,21] Despite their undeniable roles in successful host colonization, virulence factors and bacteriocins have been considered separately, with much less attention given to the latter. At very low and nonbactericidal concentrations, the peptide demonstrates modulatory properties by efficiently enhancing interferon gamma-induced nitric oxide release in murine macrophage-like cell lines
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