Antimicrobial susceptibilities of Propionibacterium acnes isolated from patients with acne lesions

Abstract number: P1652

Hui M., Fu L.H., Liu Z.H., Lam L.Y., Eastel M., Luk N.M., Chan A.K., Lo K.K., Chan C.Y.

Objectives: Prolonged antibiotic use is sometimes required for patient with acne. In the absence of routine anaerobic susceptibility testing, the choice of antibiotics is often empirical. Therefore we aimed to determine the Propionibacterium acnes susceptibility profiles from patients with acne lesions.

Methods: Patients presented to the dermatology clinic with acne lesions were recruited. Skin swabs were taken from the lesions and transported in Amies medium. These were then cultured anaerobically on horse blood agar supplemented with vitamin K for 14 days at 37°C. Identities of the organisms were confirmed by Gram's staining, biochemical reactions and short chain fatty acid production. MIC testing was performed with agar dilution method according to the CLSI M11-A7. Ampicillin, doxycycline, minocycline, erythromycin, clarithromycin, tetracycline and clindamycin were tested. Interpretive criteria for ampicillin, tetracycline and clindamycin were adopted from CLSI. Descriptive data was recorded for other antibiotics.

Results: A total of 57 isolates were collected. All of them were susceptible to ampicillin. Tetracycline and clindamycin susceptibilities were 53 (93.0%) 46 (80.7%) respectively. MIC50 and MIC90 for doxycyline were 0.25 mg/L and 2 mg/L respectively; while that of minocycline were 0.12 mg/L and 1 mg/L respectively. Erythromycin and clarithromycin MICs frequency distribution showed bimodal distribution. For erythromycin, a cluster of 46 isolates had MIC of 0.06 mg/L, while the remaining 11 isolates had MIC of geqslant R: gt-or-equal, slanted128 mg/L. These two clusters of isolates exhibited the same bimodal distribution with clarithromycin (at <0.03 mg/L and geqslant R: gt-or-equal, slanted125 mg/L).

Conclusion: Antibiotic resistance against ampicillin, tetracycline were uncommon. However, clindamycin resistance appeared to be emerging. Cross resistance with erythromycin and clarithromycin was observed, suggesting a common resistant mechanism. Minocycline and doxycycline MICs were still low when compared with previously reported data. Overall, antibiotic resistance in Propionibacterium acnes appears to be emerging and requires continue surveillance.

Session Details

Date: 10/04/2010
Time: 00:00-00:00
Session name: Abstracts 20th European Congress of Clinical Microbiology and Infectious Diseases
Location: Vienna, Austria, 10 - 13 April 2010
Presentation type:
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