Current spectrum of causative pathogens in sepsis: A prospective nationwide cohort study in Japan

Background: There is no one-size-fits-all empiric antimicrobial therapy for sepsis because the pathogens vary according to the site of infection and have changed over time. Therefore, updating knowledge on the spectrum of pathogens is necessary for the rapid administration of appropriate antimicrobials. Objective: The aim of this study was to elucidate the current spectrum of pathogens and its variation by site of infection in sepsis. Methods: This was a prospective nationwide cohort study of consecutive adult patients with sepsis in 59 intensive care units in Japan. The spectrum of pathogens was evaluated in all patients and in subgroups by site of infection. Regression analyses were conducted to evaluate the associations between the pathogens and mortality. Results: The study cohort comprised 1184 patients. The most common pathogen was Escherichia coli (21.5%), followed by Klebsiella pneumoniae (9.0%). However, the pattern varied widely by site of infection; for example, gram-positive bacteria were the dominant pathogen in bone/soft tissue infection (55.7%) and cardiovascular infection (52.6%), but were rarely identified in urinary tract infection (6.4%). In contrast, gram-negative bacteria were the predominant pathogens in abdominal infection (38.4%) and urinary tract infection (72.0%). The highest mortality of 47.5% was observed in patients infected with methicillin-resistant Staphylococcus aureus, which was significantly associated with an increased risk of death (odds ratio 1.88, 95% confidence interval 1.22–2.91). Conclusions: This study revealed the current spectrum of pathogens and its variation based on the site of infection, which is essential for empiric antimicrobial therapy against sepsis.