RESUMO
BACKGROUND: Mycoplasma pneumoniae is a frequent cause of respiratory infections in school children and adolescents. Epidemiological suspicion is important, since there are no specific symptoms or signs to help in diagnosing infection caused by this agent. OBJECTIVE: To determine the variation in prevalence over the last 10 years of M. pneumoniae IgM seropositivity according to age, particularly in pre-schoolers. METHOD: The results of M. pneumoniae IgM serological testing between January 2004 and December 2013 were analysed. Variables such as gender and month and year of sample processing were studied according to age groups (<5, 5-18, 19-50, 51-70 and >70 years of age). RESULTS: Of a total of 20,020 serological samples, 31.9% proved positive for M. pneumoniae. All age groups showed increases in percentage seropositivity over the last 10 years, although the most significant increase corresponded to the 5-18 years group (from 15.8% to 54%), followed by children <5 years of age (from 8.6% to 30%). Seropositivity was significantly higher in women in all age groups, except in those over 50 years of age. CONCLUSION: Children under five years of age were the group with the second highest increase in seropositivity.