Risk factors for pneumonia in children with Bordetella pertussis infection and co-infection status in Ningbo, China.

Objectives: Pertussis, also known as whooping cough,is a significant contributor to pneumonia cases in children. The existing literature regarding pertussis in China is sparse, highlighting the need for further research in this area. This research aimed to find out the factors related to pneumonia in B. Pertussis co-infected children.

Methods: From January to April 2024,children identified with B. Pertussis infection were enrolled in the study. Subsequently, they were divided into two groups:one consisting of those without pneumonia and another comprising those with pneumonia. This study was a retrospective observational study. In this study, variables assessed included demographics, clinical symptoms and laboratory findings. The study examined the various risk factors associated with pneumonia resulting from infection with B. Pertussis in both groups.

Results: Seventy-five patients participated in the study, Among the participants, individuals (77.30 %) had completed the full course of the pertussis vaccine, while 17 individuals (22.70 %) had not,with 29 belonging to the pneumonia group and 46 to the non-pneumonia group. There was borderline significance between the completion of vaccination and the occurrence of pneumonia (p=0.05). Those in the pneumonia group exhibited the highest recorded body temperature due to fever and increased expectoration (p<0.05). Analysis using a univariate approach indicated significant correlations between the highest body temperature during fever,the cycle threshold at the initial detection,and expectoration with pneumonia (p<0.05). Univariate logistic regression showed that the initial cycle threshold was significantly associated with pertussis-associated pneumonia (OR=1.483, p<0.001); multivariate logistic regression further confirmed it as an independent risk factor (OR=0.675, 95 % CI: 0.542-0.839, p<0.001). The group affected by pneumonia administered higher usage of erythromycin/cephalosporins (p<0.05). Both univariate and multivariate logistic regression analyses revealed a substantial relationship between the initial detection cycle threshold and pneumonia (p<0.05). 54.6 % patients had co-infections. In our pediatric population, the most commonly identified pathogens were human rhinovirus, mycoplasma pneumoniae and respiratory syncytial virus.

Conclusions: The cycle threshold values were a risk factor for pneumonia in children with B. Pertussis infection,a lower initial Ct value (indicating higher bacterial load) is a significant risk factor for developing pneumonia in children with pertussis. There was higher usage of erythromycin/cephalosporins in the pneumonia group. While B. Pertussis has a high coinfection rate in childhood infections, mainly with HRV,MP and RSV, which also highlighed the importance of comprehensive pathogen detection. Clinical doctors should fully consider the above situation in children with B. Pertussis infection to diagnose and treat correctly.