Fixed drug eruption following metronidazole therapy and the use of topical provocation testing in diagnosis

Metronidazole Induced Cutaneous Adverse Drug Reaction- A Systematic Review of Descriptive Studies

BACKGROUND

A substantial number of research studies on metronidazole-related cutaneous symptoms have recently been published. Our objective was to identify and evaluate descriptive studies that described metronidazole-related skin manifestations, therapeutic interventions, and consequences.

METHODS

A comprehensive literature search was carried out in the PubMed, Scopus, and grey literature databases from inception to April 2022 without any constraints, as well as a snowball search in Google and a search in Google Scholar. Descriptive articles describing metronidazole-related cutaneous manifestations were considered for the review. Two distinct reviewers carried out the research selection, data extraction, and quality assessment; any discrepancies were resolved by consensus with the third reviewer.

RESULTS

About 24 out of 4648 descriptive studies, including 26 patients (20 Female patients and 6 male patients), were included in this review. The included studies comprised a range of ages from 16 to 78 years old. Metronidazole was indicated for the treatment of bacterial vaginosis, trichomoniasis, sepsis, anti-infection therapy, perforated appendicitis, rosacea, vaginal discharge, dysentery, acne rosacea, trichomonal vaginitis, lichen planus, liver abscess, facial rosacea, intestinal amoebiasis, and gingivitis. Fixed drug eruption was the most common skin manifestation which was reported in 7 cases included in this review. Cutaneous manifestations were ameliorated by cessation of the offending drug and by apportioning antihistamines, topical steroids, parenteral corticosteroids, emollients, and topical moisturizers.

CONCLUSION

Clinicians and healthcare professionals should be cognizant of the potential cutaneous adverse drug reactions (CADRs) induced by metronidazole to mitigate fatal circumstances. The management of the CADRs appears to respond effectively with immediate drug discontinuation and supportive therapy.

Hypersensitivity reactions to metronidazole

BACKGROUND

Hypersensitivity reactions to metronidazole are infrequently described. However, we believe that such reactions are increasing due to growing use of the drug for the treatment of amebiasis and anaerobe infections combined with other antibiotics. The present study assesses the need for oral provocation in patients with probable hypersensitivity reactions to metronidazole.

METHODS

We performed cutaneous prick tests with spiramycin and metronidazole as well as epicutaneous tests with metronidazole at different concentrations in four patients with cutaneous reactions to Rhodogil (metronidazole plus spiramicyn). Controlled oral challenges were then carried out with placebo using erythromycin, spiramycin and metronidazole except in the last patient due to a positive prick test.

RESULTS

Only one patient showed a positive metronidazole prick test. The epicutaneous tests were negative. All patients tolerated erythromycin and spiramycin up to therapeutic doses. Oral provocation with metronidazole proved positive, the first patient presenting a delayed exanthema and the other two early erythema and itching.

CONCLUSIONS

We present four cases of cutaneous exanthemas caused by metronidazole (two early and two delayed) and probably mediated by an immune mechanism which we have only been able to demonstrate in one case. Taking into account the low sensitivity of the cutaneous tests (prick tests and epicutaneous tests), oral provocation must be considered the "gold standard" for establishing the diagnosis in many cases of hypersensitivity reactions to metronidazole.