Multicenter prospective epidemiological studies and case-control study on Haemophilus influenza infection in hospitalized neonates

Objective To explore the status of infection, biotype and resistant background of epidemic strains of Haemophilus influenza(Hi) in neonates, and the clinical features of neonatal pneumonia caused by Hi. Methods The multicenter prospective epidemiological cross-sectional design was used; four hospitals in west Sichuan China were chosen as research field, sputum bacterial culture was done and biological typing, PCR identification and drug sensitivity test of Hi epidemic strains were carried out among 0 to 28 days hospitalized neonates with infectious pneumonia in four hospitals located in west Sichuan China.The cases with discharge diagnosis of neonatal infectious pneumonia with Hi positive separation were assumed as case group, and the same number of cases with Hi negative separation were assumed as control group according to 1∶1 extraction at the same time. Results Totally 757 cases with admitting diagnosis of neonatal infectious pneumonia in four hospitals were investigated in west Sichuan from November 2014 to October 2015, and the rate of sputum culture was 95.51%(723/757). The total pathogenic bacteria positive rate of sputum culture was 15.63%(113/723), and Hi positive rate was 1.94%(14/723), Hi accounting for 12.39%(14/113) of the pathogenic bacteria in respiratory system.All the Hi strains(100%) were non-typeable Haemophilus influenzae(NTHi) indentified by PCR.The main biotypes of 14 Hi strains were typeⅠwith 57.1%(8/14), type Ⅲ with 14.3%(2/14) and type Ⅳ with 28.6%(4/14). The total of 35.7%(5/14) bacterial strains of β-lactamase distributed in four hospitals, 7.1%(1/14) bacterial strains of β-lactamase-nonproducing-ampicillin-resistant, and 35.7%(5/14) bacterial strains of β-lactamase-positive-ampicillin-resistant were found in four hospitals.The rate of resistance and mediation to cefuroxime were 14.2%(2/14) respectively, the resistance rate to cefaclor was 35.7%(5/14), and 21.4%(3/14) to ofloxacin.None of the 14 strains was resistant to amoxicillin clavulanic acid and cefotaxime.The 1∶1 matching analysis had been done for 10 cases with discharge diagnosis of neonatal pneumonia caused by Hi.There were no statistical differences in general conditions, main symptoms, lung signs, X-ray appearance, classification of leukocyte and C-reactive protein levels between case group and control group(P>0.05). Conclusion All the Hi isolated from sputum were NTHi among 0 to 28 days inpatients with neonatal pneumonia and the main biotype were type Ⅰ, type Ⅲ and type Ⅳ in west Sichuan China.There were no significant differences in the clinical manifestations of neonatal pneumonia with NTHi infection and other infectious pneumonia. Key words: Haemophilus influenzae; Infectious pneumonia; Epidemiology; Resistance rate; Neonate