Antibiotic resistance amongst cutaneous propionibacteria from Egyptian acne patients

Abstract number: 1734_24

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: Antibiotics are widely used to treat acne, with the aim of reducing levels of Propionibacterium acnes on the skin. Unfortunately, this species is rarely cultured and sensitivity profiles determined, before prescriptions are written. Little work has been done in Egypt on drug resistance in cutaneous propionibacteria, and there is no surveillance data to inform clinical decisions. Anti-acne drugs are widely available, including over the counter. This study aimed to 1) investigate antibiotic-resistant propionibacteria amongst acne patients and controls in Cairo and 2) screen for any resistance to triclosan, which is being increasingly used in skin cleansers.

Methods: 52 acne patients (attending two dermatology clinics), 36 age-matched controls from the community (no antibiotics taken in past 3mths), and 13 dermatology staff were sampled. Swabs of the face were used to inoculate plates of tryptone yeast extract glucose (TYEg) agar containing 6 mg/L furazolidone ± breakpoint concentrations of tetracycline (TET 5 mg/L), erythromycin (ERY 0.5 mg/L), clindamycin (CLIN 0.5 mg/L) and triclosan (TRIC 4 mg/L). After anaerobic incubation at 37°C for 7 days, growth of colonies morphologically resembling propionibacteria was scored.

Results: Propionibacteria were cultivated from the skin of all participants except one control. For all three cohorts, CLIN was the most common resistance encountered, being detected amongst 26.9% patients, 38.5% staff, 41.7% controls. For ERY, the prevalences were 13.5, 23.1 and 33.3% respectively. Controls were more likely than patients to carry ERY resistant strains (p = 0.016). In total, 18.8% of people had both ERY and CLIN resistant strains. TET resistant strains were isolated from just 2 (3.8%) patients, compared to 7.7% of staff and 11.1% of controls. Patients taking antibiotics were no more likely to carry resistant strains than those who were not. Amongst the staff, 5 of 13 were colonised with strains having at least one resistance, including all those who specialised in treating acne. No resistance to TRIC was detected.

Conclusions: Commensal carriage of propionibacteria resistant to drugs used to treat acne was common in this Egyptian survey. The finding of CLIN resistance in the absence of ERY resistance for propionibacteria is unusual, and the mechanism remains to be elucidated. The slightly lower incidence of drug resistant strains amongst patients merits further investigation of treatment practices in this area.