RESUMEN
Objective:To examine whether the mixed infection rate in pertussis infants is significantly higher than that in non-pertussis infants with respiratory tract infection, to explore the mixed infection pathogen distribution in pertussis infants, and to provide reference for clinical diagnosis and treatment.Methods:A case-control study was conducted on 118 nasopharyngeal swabs collected from infants who applied for clinical pertussis etiological testing (culture and specific nucleic acid detection of Bordetella pertussis) in Beijing Children′s Hospital, Jiaxing Maternity and Child Health Care Hospital and Wuhu No.1 People′s Hospital from August 2018 to January 2021.According to the pertussis etiological testing results, the patients were divided into the pertussis group (65 cases) and non-pertussis group (53 cases). Thirty-three pairs of cases were matched according to age, onset season and city.All nasopharyngeal swabs were tested for infections of other pathogens using FilmArray RP2, which can detect 21 respiratory infection pathogens.The mixed infection rate was compared between groups by Chi- square test. Results:According to the FilmArray RP2 test results, 56.9%(37/65) cases in pertussis group and 15.1%(8/53) cases in the non-pertussis group were positive for multiple pathogens, and the difference was statistically significant ( χ2=21.651, P<0.001). The top 5 mixed infection pathogens in pertussis infants were human rhinovirus/enterovirus (HRV/EV) (38.5%, 25/65), parainfluenza virus (PIV) (18.5%, 12/65), respiratory syncytial virus (RSV) (10.8%, 7/65), coronavirus (Cov) (10.8%, 7/65), and adenovirus (ADV) (7.7%, 5/65). The mixed infection rates of the pertussis group in spring, summer, autumn and winter were 46.2% (6/13), 58.3%(14/24), 55.6%(5/9), and 63.2%(12/19), respectively.Comparison of matched and unmatched cases achieved similar results. Conclusions:Among clinical suspected pertussis infant specimens, the mixed infection rate in confirmed cases is tremendously higher than that in non-pertussis infants.The main mixed infection pathogens in pertussis infants are HRV/EV, PIV, RSV, Cov, and ADV.Mixed infection in pertussis children commonly occurs in four seasons, with the highest incidence in winter.