Biology subjects

Kaplan, J. B.

Publications and source records attributed to Kaplan, J. B..

4 recordsLinked to original sources

bioRxiv2023

Synergistic activity of dispersin B and benzoyl peroxide against Cutibacterium acnes biofilms

Cutibacterium acnes has been implicated in the pathogenesis of acne vulgaris. C. acnes forms biofilms which may contribute to host colonization and antimicrobial resistance. Poly-N-acetylglucosamine (PNAG) is an exopolysaccharide that mediates C. acnes biofilm formation. In this study we investigated the ability of the PNAG-degrading enzyme dispersin B to sensitize C. acnes biofilms to killing by the anti-acne agent benzoyl peroxide (BPO). C. acnes biofilms were cultured aerobically in glass tubes in the presence of Staphylococcus epidermidis which has been shown to stimulate C. acnes biofilm formation. Biofilms were treated with 5-80 g/ml dispersin B and/or 0.1-2.5% BPO. Treatment of biofilms with dispersin B or BPO alone resulted in a 1-2 log reduction C. acnes CFUs, whereas treatment of biofilms with dispersin B followed by BPO resulted in a >6 log reduction in C. acnes CFUs. Concentrations as low as 5 g/ml dispersin B and 0.5% BPO efficiently eradicated C. acnes from the dual-species biofilm. Our findings confirm that PNAG protects C. acnes from benzoyl peroxide killing and demonstrate that dispersin B and BPO act synergistically to kill C. acnes biofilm cells. Dispersin B may be a useful adjunct to BPO for the treatment and prevention of acne.

microbiology↗

bioRxiv2023

Micrococcal nuclease regulates biofilm formation and dispersal in methicillin-resistant Staphylococcus aureus USA300

Biofilm formation is an important virulence factor for methicillin-resistant Staphylococcus aureus (MRSA). The extracellular matrix of MRSA biofilms contains significant amounts of double-stranded DNA. MRSA cells also secrete micrococcal nuclease (Nuc1) which degrades double-stranded DNA. In this study we used a nuc1 mutant strain to investigate the role of Nuc1 in MRSA biofilm formation and dispersal. Biofilm was quantitated in microplates using a crystal violet binding assay. Extracellular DNA (eDNA) was isolated from colony biofilms and analyzed by agarose gel electrophoresis. In some experiments, broth or agar was supplemented with sub-MIC amoxicillin to induce biofilm formation. Biofilm erosion was quantitated by culturing biofilms on rods, transferring the rods to fresh broth, and enumerating CFUs that detached from the rods. Biofilm sloughing was investigated by culturing biofilms in glass tubes perfused with broth and measuring the sizes of the detached cell aggregates. We found that a nuc1 mutant strain produced significantly more biofilm and more eDNA than a wild-type strain in both the absence and presence of sub-MIC amoxicillin. nuc1 mutant biofilms grown on rods detached significantly less than wild-type biofilms. Detachment was restored by exogenous DNase or a wild-type nuc1 gene on a plasmid. In the sloughing assay, nuc1 mutant biofilms released cell aggregates that were significantly larger than those released by wild-type biofilms. Our results suggest that Nuc1 modulates biofilm formation, biofilm detachment, and the sizes of detached cell aggregates. These processes may play a role in the spread and subsequent survival of MRSA biofilms during biofilm-related infections.

microbiology↗

bioRxiv2023

Staphylococcus epidermidis enables Cutibacterium acnes to form biofilms under aerobic conditions

Staphylococcus epidermidis and Cutibacterium acnes are among the most abundant members of the human skin microbiome. Both species are associated with skin health and disease. Although skin microbes typically grow in surface-associated biofilms, few studies on the interaction between S. epidermidis and C. acnes in biofilms have been reported. In the present study we measured the ability of S. epidermidis and C. acnes, either individually or jointly, to form biofilms in glass culture tubes. Since S. epidermidis is a facultative anaerobe and C. acnes is an aerotolerant anaerobe, tubes were incubated both aerobically and anaerobically to assess the role of atmosphere in biofilm forma4on. When cultured individually, we found that S. epidermidis formed biofilms under both aerobic and anaerobic conditions, whereas C. acnes formed biofilms only under aerobic conditions. When co-cultured, the presence of C. acnes had no effect on S. epidermidis biofilm formation under either aerobic or anaerobic conditions. However, the presence of S. epidermidis significantly enhanced the growth of C. acnes biofilms under anaerobic conditions and enabled C. acnes to form biofilms under aerobic condi2ons. This finding may be clinically relevant to the interaction between S. epidermidis and C. acnes on human skin.

microbiology↗

bioRxiv2023

Poly-N-acetylglucosamine mediates Cutibacterium acnes biofilm formation and biocide resistance

Biofilm formation likely plays an important role in the pathogenesis of implant-related infections caused by Cutibacterium acnes. Biofilms protect bacteria from antimicrobials and host defenses which makes biofilm-related infections difficult to treat. Here we demonstrate that the exopolysaccharide poly-N-acetylglucosamine (PNAG) contributes to C. acnes biofilm formation in vitro. By treating C. acnes cells and biofilms with the PNAG-degrading enzyme dispersin B, we found that PNAG mediates the attachment of C. acnes cells to polystyrene rods and the formation C. acnes biofilms in glass and polypropylene tubes. We further show that PNAG protects C. acnes biofilm cells from killing by tetracycline and benzoyl peroxide. PNAG may play an important role in biofilm formation, antibiotic tolerance, and virulence in this opportunistic pathogen.

microbiology↗