Background: Neonatal sepsis (NS) is one of the leading causes of infant morbidity and mortality, but little is known about pathogen incidence and distribution in China.
Methods: In this retrospective study (January 2012 to December 2016), culture-proven cases aged less than 28 days with diagnosed NS in the Guangzhou Women and Children’s Medical Center, South China, were analyzed for pathogen incidence and antimicrobial resistance.
Results: A total of 620 isolates were identified from 597 NS cases. Gram-negative bacteria (n=371, 59.8%) dominated over Gram-positive bacteria (n=218, 35.2%) and fungi (n=30, 4.8%). Klebsiella pneumoniae  (21.9%), Escherichia coli  (21.9%), group B Streptococcus  (GBS, 13.2%), and Staphylococcus aureus  (6.8%) were the four most predominant pathogens. In early-onset sepsis (EOS), GBS (30.0%) and E. coli  (20.0%) were dominant, whereas in late-onset sepsis (LOS), K. pneumoniae  (25.6%) and E. coli  (22.4%) were dominant. E. coli  (25.2%) and GBS (17.7%) were the most frequently isolated from term patients, whereas K. pneumoniae  was the most frequently isolated from preterm patients (34.9%). Of the infected infants, 9.5% died from sepsis, most commonly by E. coli  infection (16.2%). Among 91,215 live births (LBs) delivered in the study hospital (2012–2016), 252 infants developed sepsis infection (2.76 per 1000 LBs, 95% CI 2.4–3.1), including EOS (0.78 per 1000 LBs) and LOS (2.13 per 1000 LBs). All GBS isolates were susceptible to β-lactam antibiotics, and S. aureus , including methicillin-resistant isolates, were susceptible to vancomycin. An extended-spectrum β-lactamase producer was identified in 37.3% of E. coli  and 50.4% of K. pneumoniae .
Conclusion: K. pneumoniae  was the most frequent pathogen in culture-proven NS in South China, primarily associated with LOS in preterm, whereas GBS was the dominant pathogen in EOS. E. coli  was common in both episodes with the highest mortality.
Keywords: neonatal sepsis, incidence, antimicrobial resistance, Escherichia coli , group B Streptococcus , Klebsiella pneumoniae