Objective To carry out an epidemiological analysis on an outbreak of Mycoplasma pneumoniae infection at a welfare institution to provide a theoretical basis for the corresponding prevention and control measures.

Methods Using the method of field epidemiological investigation， special field treatment was carried out in September 2022. Serum samples from cases and close contacts in the same ward area were collected for detection of nine respiratory tract infection pathogens （Mycoplasma pneumoniae， chlamydia， influenza， human metapneumosis， respiratory syncytial， human boca， parainfluenza type 1‒4 virus， and Middle East respiratory syndrome， severe acute respiratory syndrome coronavirus） by immunofluorescence immunoglobulin M （IgM） antibody test.

Results A total of 14 Mycoplasma pneumoniae cases were identified， all of whom were residents of the welfare institution. The first case occurred on September 4， while the last case was reported on September 13. The incidence rate of the fifth ward area where the first case reported was 12.82% （10/78）， and it was 3.57% （3/84） in the third ward area and 1.20% （1/83） in the first ward area. There was a significant difference in incidence rates between ward areas （χ²=8.90， P<0.05）， but no significant difference was observed in age distribution and length of hospitalization. Thirty-three samples were collected for detection of nine kinds of IgM antibodies against respiratory pathogens. The results showed that the Mycoplasma pneumoniae IgM antibody was weakly positive in the 14 cases.

Conclusion Based on the epidemiological history， clinical symptoms and laboratory tests， it was concluded that it was an outbreak of Mycoplasma pneumoniae infection within the welfare institution. Welfare institutions should continue to control the occurrence and outbreak of infection through effective routine hygiene， ventilation， and disinfection so as to ensure the health and safety of their clients.