Association of Acne Severity with Antimicrobial Resistance and Biofilm Formation of Cutibacterium acnes Among Patients Attending a Tertiary Care Centre: A Cross-Sectional Study

Abstract

Background: Acne vulgaris is a common chronic inflammatory disorder of the pilosebaceous unit in which Cutibacterium acnes contributes to follicular inflammation. Antimicrobial resistance and biofilm formation may contribute to bacterial persistence and influence therapeutic response. Understanding the relationship between clinical severity and microbiological characteristics may assist in optimizing antimicrobial use in acne management.

Objective: To evaluate the association of acne severity with antimicrobial resistance and biofilm-forming capacity of C. acnes among patients with acne vulgaris attending a tertiary care centre.

Methods: A hospital-based cross-sectional observational study was conducted over 12 months among 150 patients with clinically diagnosed acne vulgaris attending the Department of Dermatology and Venereology at a tertiary care centre. Clinical severity was categorized as mild, moderate or severe using a predefined clinical grading system. Appropriate lesion specimens were collected aseptically and processed for anaerobic culture. Confirmed C. acnes isolates were subjected to antimicrobial susceptibility testing against clindamycin, erythromycin, azithromycin, doxycycline, tetracycline and minocycline. Biofilm-forming capacity was assessed using a microtiter-plate crystal-violet assay.

Results: Among the 150 patients, 68 (45.3%) yielded C. acnes. Mild, moderate and severe acne were present in 43 (28.7%), 71 (47.3%) and 36 (24.0%) patients, respectively. Among the 68 C. acnes isolates, resistance was highest to clindamycin [32 (47.1%)], followed by azithromycin [25 (36.8%)] and erythromycin [17 (25.0%)]. Resistance to doxycycline, minocycline and tetracycline was observed in 14 (20.6%), 9 (13.2%) and 8 (11.8%) isolates, respectively. Strong biofilm formation was observed in 34 (50.0%) isolates, moderate formation in 23 (33.8%) and non/weak formation in 11 (16.2%). Resistance to at least one tested antimicrobial was observed in 12 (63.2%) mild, 21 (77.8%) moderate and 19 (86.4%) severe cases; however, the association between acne severity and any antimicrobial resistance was not statistically significant (p=0.213). Previous antibiotic exposure was significantly associated with antimicrobial resistance (p=0.018).

Conclusion: The study demonstrates a substantial burden of antimicrobial resistance and biofilm formation among C. acnes isolates obtained from patients with acne vulgaris. Although antimicrobial resistance showed a numerical increase with increasing acne severity, the association was not statistically significant. The findings emphasize the importance of local antimicrobial susceptibility surveillance, rational antibiotic use and consideration of microbiological characteristics when investigating persistent or treatment-resistant acne.