The case

The patient, a 58 ­ year ­ old female in good health with no chronic health conditions, underwent an operation to remove a mole on the sole of her left foot. It was performed under a local anesthetic of 2% lidocaine, followed by loose stitch suture with polyamide 4.0. The wound was dressed with a non­adherent hyaluronic acid based dressing to which a silver sulfadiazine hydrogel was applied on top, in alignment with internal protocol for surgical operations.

The choice of an hydrogel formulation in the areas with a greater thickness of the epidermis was made with the aim of maintaining a minimum level of paraphysiological hydration, in addition to the advantage given by the greater permeability of this formulation between the stitches of the suture, thus ensuring the deep penetration of antibacterial compared to creams or ointments.

Following discharge, a prophylaxis antibiotic, once a day for 5 days, with Cefixime 400 mg was prescribed.

The same evening the patient called the surgeon, complaining about some kind of itching and of a moderate swelling of the foot. She was advised to sleep with a pillow beneath her foot.

The morning after a condition of clear angioedema of the entire foot, associated with an increased itching was reported; due to for this reason it was decided to remove the dressing and apply a normal plaster. The patient was summoned for an examination the next day.

From an anamnestic integration, the patient recalled another episode of drug allergy, consisting in a diffuse erythema of the body which occurred at the age of 16 following the intake of Sulfamethoxazole in association with trimethoprim.

Certain of the allergic etiology, removal. systemic antibiotic therapy was not modified.

The situation is shown in Pic. 1.

At the physical examination the situation appeared spontaneously improved, with negative thermotact and appreciable arterial pulse everywhere, as shown in Pic. 2 ; the wound showed no signs of infection and the allergic etiology of the adverse event was clearly evident and confirmed by the spontaneous reduction of symptoms after removing the topical therapy.

It was decided not to prescribe any therapy and to evaluate the evolution in the next 24 hours, reserving, however, the possibility of prescribing antihistamines and steroids, only if necessary.

The following day the foot was back to normal and the wound healed without problems, with removal of the suture in the twentieth day. To the patient was advised to conduct an allergy study targeted to antibiotics not before another 3 weeks.

Discussion and conclusion

The take home message from this experience is that the formulations of topical therapies in ointment and hydrogel or their delivery through liposomes / nanoparticles increase the local absorption (and, in a very moderate quantity, the systemic one) of the active principles contained in them, causing sometimes also a greater allergic response even with atypical manifestations, such as local angioedema.

In order to avoid such side effects to the patient, it is always advisable to pay the utmost attention to the anamnesis, even in the simplest interventions and it is mandatory to avoid the applications of topical antibiotics in wounds of patients allergic or potentially allergic to the active ingredient.

Fortunately, most of these events resolve in a few days and without any therapy, with the exception of the treatment of itching, that may require the use of antihistamines.

Disclosures:

The Author declare that he has no relationships relevant to the contents of this paper to disclose.

Manuscript received July 16, 2021; revised September 16, 2021; accepted October 18, 2021.