D2.248 - Allergy to quinolones: a clinical case

Quinolones are the second most common group of antibiotics in inducing allergic reactions, after beta-lactams. Most adverse reactions to quinolones are immediate and severe. Ciprofloxacin, moxifloxacin and levofloxacin are the main causal agents of anaphylactic and anaphylactoid reactions.

We present the case of a 65-year-old female patient without any drug allergy and a personal history of hypothyroidism and colon cancer. In 2022 she was admitted to the emergency room due to ileitis. Intravenous ciprofloxacin was administered and 3 minutes after starting the infusion, she developed generalized and ocular itching and conjunctival redness. After that, she started with oropharyngeal occupation sensation. On physical examination, three wheals were observed on her back. 40 mg of intravenous methylprednisolone and 5 mg of dexchlorpheniramine were administered, with resolution of symptoms. Tryptase levels were not measured.

Skin tests to quinolones were performed.

Prick test (PT) to ciprofloxacin and levofloxacin: negatives. PT to moxifloxacin: 4 mm (histamine 7 mm). Intradermal test (IDT) to ciprofloxacin 0.02mg/mL: 11 mm (histamine 15 mm). IDT to levofloxacin 0.05 mg/mL: 9 mm.

The patient was diagnosed with allergy to quinolones.

The increase of the incidence of hypersensitivity reactions to quinolones in recent years could be due to an increase in their prescription given their wide range of antibacterial activity and ease of administration.

Skin tests have certain limitations, producing false negative and positive results (when are testing in high concentration). For this reason, drug provocation test is considered the gold standard for diagnosis and is also useful for identifying safe alternative quinolones, although it is not free of risk.

Immediate reactions may be mediated by IgE or by the activation of MRGPRX2, the latter may occur in patients without previous exposure to quinolones. Both produce indistinguishable symptoms and can result in positive skin tests. 

The basophil activation test is considered to have higher sensitivity than the skin tests, so it should be implemented.

If the patient is allergic to quinolones, desensitization may be considered when there are no alternatives.