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Survival of antibiotic-resistant Propionibacterium acnes in the environment

Abstract number: 902_p818

Qureshi A.

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Objectives:

Antibiotic treatment for acne is aimed at reducing levels of the anaerobe, Propionibacterium acnes, on skin. Treatment can involve long and multiple courses of antibiotics, and patients are often colonised with resistant strains. It is not clear if such strains develop de novo or are transferred directly or indirectly between individuals. It has been assumed P. acnes do not survive well in the environment. This study aimed to test if this is the case by modelling their survival on surfaces.

Methods:

The P. acnes type strain, NCTC737, was used to assess survival under different environmental conditions. Approximately 10 exp 7 to 10 exp 8 washed cells were dried onto individual glass coverslips and maintained under different conditions of temperature, relative humidity (RH) with and without oxygen. Triplicate samples were assayed for up to 77 days. Standard conditions (20°C, 31% RH) were used to assess the survival of 10 antibiotic resistant (erythromycin or tetracycline resistant) isolates and one fully suceptible clinical isolate.

Results:

P. acnes NCTC737 survived in air for >77 days at 20°C, 31% RH (3 log reduction). Survival was adversely affected at 15% RH, 20°C (3 log reduction over 1 day) and 37°C, 31% RH (3 log reduction over 1 day 22 h). Survival was poor at 6°C, 31% RH (3 log reduction over 12 days 15 h) and under anaerobic conditions, 20°C, 31% RH (3 log reduction over 7 days 7 h). Survival of the 10 resistant P. acnes isolates at 20°C, 31% RH was variable and eight strains had reduced survival (3 log reduction between just 2–14 days), compared with NCTC737 and the susceptible clinical isolate (3 log reduction >28 days). Two strains, one tetracycline and one erythromycin resistant, were more resilient with 3 log reductions taking >17 days. Viable cells could be recovered after 17 days with all strains.

Conclusions:

Although P. acnes is sensitive to oxygen, it can survive on surfaces for extended periods at room temperature in air. Antibiotic resistant clinical isolates remained viable on surfaces for at least 17 days. These results suggest strains can be transmitted between acne patients via inanimate objects. Infection control policies in dermatology clinics should take these findings into account.

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Session Details

Date: 01/08/2007
Time: 00:00-00:00
Session name: XXIst ISTH Congress
Subject:
Location: Oxford, UK
Presentation type:
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