Introduction:
Diseases caused by Corynebacterium spp. are rare in humans. The atypical clinical presentation of the infection may cause diagnostic difficulties.

Aim:
In this case report, we present the medical history of a 3-year-old patient admitted to the hospital with symptoms characteristic of Kawasaki disease.

Case study:
The child presented with a persistent fever, a red throat, conjunctival hyperaemia, enlargement of the submandibular and cervical nodes, maculopapular rash on the trunk. In the laboratory tests the significant elevation of inflammatory markers, an increased plasma concentration of N-terminal pro B-type natriuretic peptide (NT-proBNP) were observed. Additionally, the girl was not fully vaccinated. Despite the administration of antibiotic therapy, the patient's general condition deteriorated. Irregularities in heart rhythm were also noticed. For these reasons, the patient was transferred to a tertiary reference hospital. Although the criteria for Kawasaki disease were met, due to the persistent coating on both tonsils and pharynx, further diagnostics were deemed necessary. A microbiological examination revealed the cultivation of coryneform bacteria. Appropriate antibiotic treatment led to the improvement of the girl's condition.

Results and discussion:
The described case indicates two important pediatric problems. The first one concerns the diagnosis of fevers with atypical symptoms related to rare infections. The second one concerns the similarity of symptoms of infections and Kawasaki disease.

Conclusions:
Attention should be paid to the atypical course of infection, which may mimic other diseases. In the differential diagnosis, it is worth considering opportunistic infections, rare microorganisms.