Investigation of erythromycin-resistant staphylococci from the skin of Egyptian acne patients

Abstract number: 1733_1322

El-Mahdy T.S.M., Abd-Elaziz M.M., El-Sayed M.H., Ross J.I., Abd-Allah S., Radwan H., Snelling A.M.

Objectives: Long courses of antibiotics remain the mainstay of acne treatment. Whilst Propionibacterium acnes is being targeted, selective pressure is also exerted on other members of the commensal skin flora, including coagulase negative staphylococci (CNS) such as Staphylococcus epidermidis. These bacteria may then act as reservoirs of resistance genes for more pathogenic strains or species. Erythromycin (ERY) is widely used in Egypt to treat acne, and available over the counter, but it is not known how this is affecting the commensal flora. This study sought to determine the prevalence of ERY resistant CNS, and the genes responsible, from acne patients attending clinics in Cairo.

Methods: Fifty-two acne patients, 13 dermatology staff and 36 controls were studied. Facial skin swabs were taken, and inoculated onto Mueller Hinton agar containing 4 mg/L ERY (breakpoint concentration). Plates were incubated at 35°C for 48hrs. ERY resistant staphylococci were identified by standard tests. MIC profiles for other drugs commonly used in dermatology were determined using CLSI criteria. Resistance determinants were identified by PCR using primer pairs specific for erm(A), erm(B), erm(C), and msr(A).

Results: The prevalence of ERY resistant CNS amongst patients, clinic staff, and controls was 80.8%, 69.2%, and 66.7%, respectively. These differences were not significant (p > 0.05) and patients on current or very recent antibiotic treatment were no more likely than those using other or no medication to carry ERY-R strains. A total of 42 ERY-R strains were isolated from 42 different patients. 54.5% of these had high level resistance (MIC > 1024 mg/L). The most widely-distributed erythromycin resistance determinants were erm(C) alone (42.9% strains), msr(A) (40.5%) or both together (16.7%). Erm(A) and erm(B) were not detected. Amongst the 42 strains, cross-resistance to tetracycline (64.3%), clindamycin (9.5%), or fusidic acid (45.2%) was detected.

Conclusions: Although high (80.8%) carriage of ERY resistant CNS amongst Egyptian acne patients is comparable to that reported from Western countries, and was not significantly different from carriage amongst the non-patients. Prevalence of msr(A) (>half strains tested) was much higher than expected, and the driver for this remains to be elucidated. Carriage of CNS with multiple resistances to drugs used to treat dermatological conditions was common, and is of concern for treatment of staphylococcal skin infections in Egypt.

Session Details

Date: 31/03/2007
Time: 00:00-00:00
Session name: European Society of Clinical Microbiology and Infectious Diseases
Location: ICC, Munich, Germany
Presentation type:
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