Abstract: Objective　To investigate the clinical features of children with severe pertussis in Chongqing. Methods Clinical characteristics of 72 cases of severe pertussis admitted to the Children's Hospital of Chongqing Medical University from January 2013 to June 2018 were retrospectively analyzed. Results　Children under 6 months old had a higher incidence. Severe pertussis was distributed throughout the year and more common in winter and spring. Sixty-two cases (86.1%) were not vaccinated with DTP. Thirty-three cases (45.8%) with underlying diseases were more common with malnutrition (51.5%) and congenital heart disease (39.4%). There were 65 cases (87.5%) of leukocytosis. Respiratory complications were more common in respiratory failure (93.1%) and severe pneumonia (84.7%). Extrapulmonary complications were mainly cardiac insufficiency (18.1%) and pertussis encephalopathy (18.1%). Sixty-three cases (87.5%) had leukocytosis. Common respiratory complications were respiratory failure (93.1%) and severe pneumonia (84.7%). Extrapulmonary complications were cardiac insufficiency (18.1%) and pertussis encephalopathy (18.1%). Fifty-two (72.2%) children were infected with pathogens, and 39 (75.0%) were in winter and spring. The virus of community acquired infection was mainly RSV (72.4%); the first bacterial pathogen was Klebsiella pneumoniae (23.9%), and the major nosocomial bacterial pathogen was Klebsiella pneumoniae pneumonia and Acinetobacter baumannii. Twenty-nine cases (40.3%) had viral infection and the predominant virus was RSV. Fourty-six cases (63.9%) had bacteria infection. The main bacteria infection was Klebsiella pneumoniae, Staphylococcus aureus and Acinetobacter baumannii. With anti-infection, respiration, circulatory support and symptomatic treatment, 20 cases (27.7%) died. Comparative analysis showed that the WBC peak and incidence of hypoglycemia were significantly higher in the death group than that in the survival group (56.13±36.97 vs 31.56±22.16, P<0.05; 5.8% vs 30%, P<0.05, respectively). The ROC curves of peak WBC for predicting death of severe pertussis was drawn. It was found that peak WBC>36.58×109/L was of high value in predicting death of severe pertussis. The predicted sensitivity and specificity were 0.700 and 0.712, respectively, and the corresponding AUC=0.701. Conclusions　Severe pertussis in Chongqing mostly attacked infants without DTP vaccination. They were always combined with Klebsiella pneumoniae infection, nosocomial Acinetobacter baumannii infection or community RSV infection. Moreover, the cases which have hypoglycemia and those WBC peak > 36.58 × 109/L are prone to death.

Key words: pertussis;　other respiratory pathogens;　clinical characteristics; child