Cutibacterium acnes biofilm forming clinical isolates modify the formation and structure of Staphylococcus aureus biofilms, increasing their susceptibility to antibiotics

Abbott, Carmel, Grout, Elena, Morris, Trefor and Brown, Helen L. 2022. Cutibacterium acnes biofilm forming clinical isolates modify the formation and structure of Staphylococcus aureus biofilms, increasing their susceptibility to antibiotics. Anaerobe 76 , 102580. 10.1016/j.anaerobe.2022.102580

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Abstract

Cutibacterium acnes (formally Propionibacterium acnes) is frequently identified within surgical device related infections. It is often co-isolated from infection sites with other opportunistic pathogens. Recent studies have demonstrated that C. acnes is able to form biofilms and when co-cultured with Staphylococcus spp. both inhibitory and stimulatory effects have been reported across several studies. Here, we investigated the biofilm-forming ability of 100 clinical C. acnes isolates from various infection sites in human patients, both deep tissue and superficial, followed by an investigation of how the supernatants of C. acnes cultures influenced the attachment and maturation of S. aureus NCTC 6571 biofilms. All of the C. acnes isolates were able to form biofilms in vitro, although biofilm biomass varied between isolates. Nineteen isolates were weakly adherent, 33 were moderately adherent and the majority (48) showed strong adherence. The presence of C. acnes sterile supernatants reduced the biomass of S. aureus cultures, with a > 90% reduction observed in the presence of several of the C. acnes isolates. We observed that this decrease was not due to C. acnes affecting S. aureus viability, nor due to the presence of propionic acid. Biofilm maturation was however delayed over a 24-hour period as was biofilm surface structure, although initial (up to 8 h) surface attachment was not affected. We hypothesis that this defective biofilm maturation is the cause of the observed biomass decrease. In turn, these altered biofilms showed a greater susceptibility to antibiotic treatments. In contrast the presence of C. acnes supernatant in planktonic (defined as a free moving, non-surface attached population within the liquid column) S. aureus cultures increased antibiotic tolerance, via a currently undefined mechanism. This study suggests that complex interactions between C. acnes and other opportunistic pathogens are likely to exist during colonisation and infection events. Further investigation of these interactions may lead to increased treatment options and a better prognosis for patients.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Dentistry Medicine
Additional Information:	License information from Publisher: LICENSE 1: Title: This article is under embargo with an end date yet to be finalised.
Publisher:	Elsevier
ISSN:	1075-9964
Date of First Compliant Deposit:	7 June 2022
Date of Acceptance:	28 April 2022
Last Modified:	14 May 2023 08:00
URI:	https://orca.cardiff.ac.uk/id/eprint/150248

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