Introduction Cow’s milk protein allergy is one of the most common causes of food allergy in early infancy, causing abdominal pain, diarrhoea and in almost all cases failure to thrive. The correlation between rotaviral infection – development of cow’s milk protein allergy in children is known, but no relation between a bacterial infection and cow’s milk protein allergy has been described so far.

Objectives We present the case of a 14 month old male boy whose mother had urticaria, the last episode occurring during pregnancy. He received breast milk until 4 months of age, when his mother erroneously received floroquinolones for her Staphylococcus mastitis and stopped breastfeeding. During the first four months he developped a moderate form of atopical dermatitis, although his weight gain was excelent (90^th percentile). Then, his first episodes of bloody diarrhoea occured, receiving third generation cephalosporins, despite the negative coproculture and the positive norovirus test. He received a delactosate formula and after eight days he had a severe allergic reaction with Quincke oedema. Although the Ig E antibodies for cow’s milk protein where negative at the time, the clinical status prompted the introduction of an extensively hydrolyzed milk diet. After two months he had a new diarrhoea episode, with a positive coproculture for Salmonella. He received numerous antibiotics, without any success (trimethoprim/sulfamethoxazole, amoxicillinum + acidum clavulanicum, cefpodoxime). During this time, stools were fermented, mucous, associated with abdominal pain, leading to his admission in a hospital where he received meropenem for the Salmonella infection. In the fifth day of treatment he developed a general allergic reaction to meropenem, Quincke oedema, hyporeactivity. While hospitalised, Ig E for cow’s milk protein where positive for the first time. For almost another six month he was a Salmonella carrier, with multiple allergies during solid food introduction (egg: prick test positive, carrot) all of them with cutaneous eruption, itching, sneeze. He followed a restrictive diet because of all the allergic reactions, for 4 months he only tolerated chicken meat, millet, boiled pear and extensively hydrolyzed milk.

Results and conclusion Despite the status of Salmonella carrier and multiple allergies, the correct diet favouret a great weight gain (90^th percentile), while the episodes of abdominal pain improved in terms of frequency and intensity. This case illustrates a rare occurrence of clinically severe IgE-mediated cow’s milk protein allergy in a Salmonella carrier child with good weight gain, making a normal diet a real challenge.