Shamik Ghosh

Heterogeneity and antibiotic resistance in Propionibacterium acnes isolates and its therapeutic implications: blurring the lines between commensal and pathogenic phylotypes

Acne vulgaris is a multifactorial skin disease associated with the colonization of Propionibacterium acnes. Antibiotics are a mainstay of treatment for acne, yet the emergence of resistance against the currently approved antibiotics is a serious concern. In this case report, a slow responder had multiple Propionibacterium acnes isolates with varied levels of sensitivity to the conventional antibiotics. The bacterial isolates obtained from acne samples collected from the patient were analyzed for phylogeny, and was found to be largely restricted to two different lineage patterns. Propionibacterium acnes phylotype IA1, which is considered to be pathogenic, displayed clindamycin sensitivity, but phylotype IB, which is associated with commensals, exhibited high clindamycin resistance. Sensitivity analysis revealed uniform resistance to macrolides, but susceptibility to tetracycline and nadifloxacin. These results implicate Propionibacterium acnes in the pathophysiology of acne vulgaris, although the lines between commensal and pathological phylotypes may be blurred. Switching the patient to a combination of minocycline and nadifloxacin resulted in a significant improvement in the clinical lesions. Such a science‐driven judicious selection of antibiotics can minimize the probability of development of resistance, and might be the way forward in the treatment of acne.

Synergistic antimicrobial activity of Boswellia serrata Roxb. ex Colebr. (Burseraceae) essential oil with various azoles against pathogens associated with skin, scalp and nail infections

Antimicrobials from natural sources have gained immense importance in recent times to combat the global challenge of antibiotic resistance. Essential oils are implicated in antimicrobial action against several species. Here, we have screened nine commercially available essential oils for their antimicrobial activity against organisms associated with skin, scalp and nail infections mainly Propionibacterium acnes, Malassezia spp., Candida albicans and Trichophyton spp. Among nine essential oils, Boswellia serrata essential oil demonstrated superior antimicrobial activity against all the micro‐organisms and surprisingly it showed maximum activity against Trichophyton spp. The gas chromatography–mass spectrometry analysis of B. serrata oil indicates a major composition of α thujene, ρ cymene and sabinene. Additionally, B. serrata oil was found to inhibit Staphylococcus epidermidis biofilm, and its combination with azoles has shown synergistic activity against azole‐resistant strain of C. albicans. These broad‐spectrum antimicrobial activities of B. serrata oil will make it an ideal candidate for topical use.

Antibiotic-resistant acne: getting under the skin.

Propionibacterium acnes is a key pathogenic factor in the development of acne. Antibiotics are the first choice of treatment for mild-to-moderate, mixed, papular/pustular, and moderate nodular acne, and an alternative choice in severe, nodular/conglobate acne. The emergence of resistance to the currently available antibiotics poses a serious set-back to this algorithm, and the reduced arsenal can diminish efficacy of treatment. This emerging situation should catalyze innovations in dermatology; for example, newer drugs and technologies such as next-generation antibiotics with excellent potency and low propensity to develop resistance, rapid diagnostic platforms to select responders and nonresponders, and delivery technologies that target the bacteria. Such innovations can dramatically expand the arsenal for dermatologists in the management of acne.