Low rate of co-infection in complicated infectious mononucleosis

INTRODUCTION: It remains unclarified if bacterial co-infection is common in patients with infectious mononucleosis (IM) and acute tonsillitis and/or peritonsillar abscess (PTA). Recent studies suggest that Fusobacterium necrophorum is a prevalent pathogen in acute tonsillitis and PTA. We hypothesised that this anaerobe may play a significant role for the aggravated infection and the development of PTA among teenagers and young adults with IM.

METHODS: All patients with IM and clinical findings of acute tonsillitis or PTA admitted to our department in the 2001-2015 period were included in the study.

RESULTS: In total, 257 patients with IM and acute tonsillitis (n = 220) or PTA (n = 37) were included. Positive bacterial cultures were obtained in 28% of patients with AT and in 50% with PTA. The most prevalent bacterial findings were Group C/G streptococci (14%) among patients with acute tonsillitis and Staphylococcus aureus (22%) in patients with PTA. F. necrophorum was recovered in 9% and 2% of patients with acute tonsillitis and PTA, respectively.

CONCLUSIONS: We were unable to substantiate a prevalent role for F. necrophorum in patients with IM and acute tonsillitis/PTA. S. aureus may play a role in PTA development in patients IM. The majority of our findings did not support the use of antibiotics in patients with IM, even in this selected group of patients with severe symptoms and a high risk of PTA.

FUNDING: This work was funded by the Lundbeck Foundation (Grant number R185-2014-2482).

TRIAL REGISTRATION: The Danish Data protection Agency approved the project.