Isolation and characterization of bacteriophages from the human skin microbiome that infectStaphylococcus epidermidis

Abstract

Phage therapy might be a useful approach for the treatment of nosocomial infections; however, only few lytic phages suitable for this application are available for the opportunistic pathogen, Staphylococcus epidermidis. In the current study, we developed an efficient method to isolate bacteriophages present within the human skin microbiome, by using niche-specific S. epidermidis as the host for phage propagation. S.epidermidis was identified on the forehead of 92% of human subjects tested. These isolates were then used to propagate phages present in the same skin sample. Plaques were observable on bacterial lawns in 46% of the cases where S. epidermidis was isolated. Eight phage genomes were genetically characterized, including the previously described phage 456. Six phage sequences were unique, and spanned each of the major staphylococcal phage families; Siphoviridae (n = 3), Podoviridae (n = 1), and Myoviridae (n = 2). One of the myoviruses (vB_SepM_BE06) was identified on the skin of three different humans. Comparative analysis identified novel genes including a putative N-acetylmuramoyl-L-alanine amidase gene. The host-range of each unique phage was characterized using a panel of diverse staphylococcal strains (n = 78). None of the newly isolated phages infected more than 52% of the S. epidermidis strains tested (n = 44), and non-S. epidermidis strains where rarely infected, highlighting the narrow host-range of the phages. One of the phages (vB_SepM_BE04) was capable of killing staphylococcal cells within biofilms formed on polyurethane catheters. Uncovering a richer diversity of available phages will likely improve our understanding of S. epidermidis-phage interactions, which will be important for future therapy.

Novel Bacteriophage Specific against Staphylococcus epidermidis and with Antibiofilm Activity

“…Although the latent period was the same (90 min) in all three tested bacterial strains, the burst size differed substantially between SE16 (92 PFU/cell) and SE14 or SE18 (3 PFU/cell). Other studies have reported S. epidermidis phages with burst sizes ranging from 4.3 PFU/cell to 49.3 PFU/cell [12,32,[38][39][40], of which siphoviruses showed burst sizes between 6.39 PFU/cell and 49.3 PFU/cell. Our study reports a lower and higher burst size than those previously observed.…”

“…Most of the staphylococcal phages isolated to date have been characterized in Staphylococcus aureus strains constituting a gap of knowledge on phages active against S. epidermidis. Moreover, there is only a limited number of studies investigating phage activity against S. epidermidis biofilms [11][12][13][14]. In this study, we isolated and characterized a novel bacteriophage specific to S. epidermidis and provided key data on different infectivity parameters of the phage as well as in vitro assessment of antimicrobial efficacy.…”

Complete Genome Sequence of Salmonella Phage vB_SenA_SM5, Active against Multidrug-Resistant Salmonella enterica Serovar Typhi Isolates

“…The supernatants were filtered with 0.22-μm syringe filters, and the filtrates were used for a plaque assay ( 1 ). A single plaque was selected and propagated twice as described by Valente et al ( 2 ). The phage preparation was concentrated by the addition of polyethylene glycol (10% PEG 8000), followed by ultracentrifugation at 55,000 rpm for 2 h ( 3 ).…”

Characterization of a Lytic Bacteriophage vB_SurP-PSU3 Infecting Staphylococcus ureilyticus and Its Efficacy Against Biofilm

“…Until recently, phages infecting S. aureus have been one of the most thoroughly investigated types owing to the high rate of AMRs (including MRSA) (Salas et al, 2020 ; Walsh et al, 2021 ). As nosocomial infections by CoNS increase, studies on the efficacy of phages infecting CoNS and bacterial biofilms have been conducted (Doub et al, 2021 ; Valente et al, 2021 ). However, despite their potential clinical relevance, the phages infecting S. ureilyticus are relatively scarce compared to those for other species.…”