In vitro antimicrobial efficacy of β‐defensin 3 against Staphylococcus pseudintermedius isolates from healthy and atopic canine skin

Abstract

β-Defensins (BDs) are highly conserved antimicrobial peptides important in innate defence against bacteria. β-Defensin 3 has a specific role in protecting the skin. This study quantified the minimal inhibitory concentration (MIC) of human (h)BD3 against Staphylococcus pseudintermedius isolates from atopic and healthy dogs. Single colony isolates (1 × 10(5) colony-forming units/mL log phase) were cultured with doubling dilutions of hBD3 in sodium phosphate buffer from 0.8 to 50 μg/mL at 37 °C for 2 h, before adding 100 μL of tryptone soy broth and incubating for a further 20 h. Bacterial growth was assessed as the mean optical density at 540 nm corrected for background. The median MIC was 12.5 μg hBD3/mL (range 3.125-25 μg/mL; n=22). Forty-five percent of the isolates were inhibited at ≤ 6.25 μg hBD3/mL, and 90% were inhibited at ≤ 12.5 μg hBD3/mL. Bacterial growth was not inhibited at ≤ 1.6 μg hBD3/mL. There were no significant differences in the inhibition by hBD3 of isolates from atopic (median MIC 12.5 μg/mL, range 6.25-25 μg/mL, n=14) and healthy dogs (median MIC 9.4 μg/mL, range 3.125-12.5 μg/mL, n = 8); from noninfected colonized sites (median MIC 12.5 μg/mL, range 3.125-25 μg/mL, n=16) and infected lesions (median MIC 9.4 μg/mL, range 6.25-12.5 μg/mL, n=6); or between sample sites (nose median MIC 12.5 μg/mL, range 6.25-25 μg/mL, n=5; perineum median MIC 12.5 μg/mL, range 3.125-25 μg/mL, n=7; ear median MIC 6.25 μg/mL, range 6.25-12.5 μg/mL, n=4; lesions median MIC 9.4 μg/mL, range 6.25-12.5 μg/mL, n=6). In conclusion, hBD3 inhibited the growth of canine S. pseudintermedius isolates in vitro irrespective of origin.

Activity, Expression and Genetic Variation of Canine β-Defensin 103: A Multifunctional Antimicrobial Peptide in the Skin of Domestic Dogs

“…Studies on β-defensins in skin have almost exclusively focused on human peptides [32], including investigation on expression [17,18], regulation [33,34,35] and associations with skin infection [12,13,36] and other diseases, such as psoriasis and AD [10,11]. Few studies of skin β-defensins in animal models have been reported, except for the dog model [8,15,16,24,37,38]. The current study sought to extend our knowledge of canine β-defensins by quantifying CBD103 expression in healthy skin, determine genetic variation of CBD103 amongst and within different breeds, characterize the antibacterial activity of CBD103 and CBD103ΔG23 and evaluate expression of CBD103 from lesional and nonlesional skin of dogs with AD.…”

Sphingolipids and Antimicrobial Peptides: Function and Roles in Atopic Dermatitis

“…The defensins, which have six conserved cysteine residues, are small and cationic peptides that are divided into three subfamilies, α-, β-, and θ-defensin based on the pairing of the cysteine residues to form three disulfide bridges (α-defensin [cys 1 -cys 6 , cys 2 -cys 4 , cys 3 -cys 5 ], β-defensin [cys 1 -cys 5 , cys 2 -cys 4 , cys 3 -cys 6 ], θ-defensin [cys 1 -cys 1 , cys 2 -cys 3 , cys 2 -cys 3 ]) (Ali et al ., 2001; Huh et al ., 2002; Fazakerley et al ., 2010). Six α-defensins have been identified from five genes in human, human neutrophil peptide (HNP)-1, HNP-2, HNP-3, HNP-4, and human defensin (HD)-5, and HD-6.…”

“…hBD3 has potent antimicrobial activity against exogenous microbial pathogens, including Gram-negative and Gram-positive bacteria, while hBD2 has no noted effects against Gram-positive Staphylococcus ( S .) aureus , which is the virulent bacteria that colonizes approximately 90% of AD patients (Fazakerley et al ., 2010; Ong, 2010).…”

Fluorinated antimicrobial lysine‐based peptidomimetics with activity against methicillin‐resistant Staphylococcus pseudintermedius

“…Antimicrobial peptides and peptidomimetics represent interesting therapeutic approaches for both human and veterinary antimicrobial treatment. Until now, limited attention has been given to identification of AMPs and peptidomimetics with activity against S. pseudintermedius including MRSP . Previous work comprises investigations of: (i) canine β‐defensin and cathelicidin (with MICs in the range 3‐50 μg/mL), (ii) the lantibiotic nisin and some derivatives (with MICs in the range 0.25‐2 μg/mL) showing synergy with chloramphenicol, (iii) cyclic depsipeptide antibiotics lysocin E and lotilibcin (with MICs in the range 2‐4 μg/mL), and (iv) 6 highly cationic peptides with RRIKA (WLRRIKAWLRRIKA) and WR‐12 (RWWRWWRRWWRR) found to be quite active (with MICs of 0.5‐2 and 0.5‐4 μM, respectively) against several clinical isolates …”