To explore clinical molecular epidemiological characteristics and drug sensitivity of nosocomial infection of Streptococcus agalactiae in neonates.

A total of 92 neonates who had nosocomial infection of Streptococcus agalactiae when treated in Maternal and Child Health Hospital of Guangxi Zhuang Autonomous Region from January 2015 to December 2018, were selected as research subjects. Clinical data of them were retrospectively analyzed. Chi-square test was used to compare the nosocomial infection rate of Streptococcus agalactiae among 4 wards of newborns in case collected hospital. For separated and cultured Streptococcus agalactiae, the sample source and serotyping, also their distribution characteristics were analyzed. The drug sensitivity and resistance of Streptococcus agalactiae were analyzed by paper diffusion method. This study was in line with World Medical Association Declaration of Helsinki revised in 2013. Informed consents were acquired from all guardians.

① Nosocomial infection rates in 4 neonatal wards: the rates of nosocomial infection of Streptococcus agalactiae in intensive care unit (ICU) of extremely premature infants, ICU of preterm infants, ICU of full term infants and neonatal general ward were 0.329% (5/1 521), 0.508% (18/3 545), 1.261% (48/3 807)) and 0.095% (21/22 160), respectively. Among them, the rate of neonatal nosocomial infection of Streptococcus agalactiae in ICU of full term infants were higher than those of other three wards, respectively, and the differences were statistically significant (all P<0.006). ② Specimens source: among 92 specimens which Streptococcus agalactiae were detected, the top 3 ratios of source of specimens from high to low were from respiratory secretion, venous blood and urine, their ratios were 48.9% (45/92), 22.8% (21/92) and 16.3% (15/92), respectively. ③Incidence rate of early onset sepsis (EOS): among 21 neonates whose results of blood culture with Streptococcus agalactiae positive, 71.5% (15/21) were diagnosed as EOS. ④ Serotype: among those strains of Streptococcus agalactiae from 92 specimens, the top 3 distributions of serotype typing from high to low were type Ⅲ, Ⅰb and Ⅴ, their ratios were 30.4% (28/92), 27.2% (25/92) and 21.7% (20/92), respectively. ⑤ Drug sensitivity test results: those 92 strains of Streptococcus agalactiae from 92 specimens were highly resistant to tetracycline, clindamycin and erythromycin, and drug resistance rates were 69.6% (64/92), 57.6% (53/92) and 55.4% (51/92), respectively, but they were highly sensitivity to vancomycin, penicillin, linezolid, dalfopristin and ampicillin, and drug sensitivity rates were all ≥87.0%.

Full term infants in ICU should be particularly vigilant against nosocomial infections of Streptococcus agalactiae to reduce incidence of serious infection complications such as EOS etc.. The serotypes of Streptococcus agalactiae detected in neonatal wards in our hospital were mainly type Ⅲ, Ⅰb, and Ⅴ. Antibacterials such as vancomycin, penicillin, linezolid could be used for treatment of Streptococcus agalactiae infection disease.