Blood cultures should be collected for acute cholangitis regardless of severity.

Background: Despite the high frequency of bacteremia in acute cholangitis, the indications for blood cultures and the relationship between the incidence of bacteremia and severity of acute cholangitis have not been well established. This study examined the association between the 2018 Tokyo Guidelines (TG18) severity grading for acute cholangitis and incidence of bacteremia to identify the need for blood cultures among patients with acute cholangitis in each severity grade.

Methods: Patients with acute cholangitis who visited our emergency department between 2019 and 2020 were retrospectively investigated. Patients administered antibiotics within 48 h of hospital arrival, whose prothrombin time-international normalized ratios were not measured, or who were suspected of false bacteremia were excluded.

Results: Out of the included 358 patients with acute cholangitis, blood cultures were collected from 310 (87%) patients, of which 148 (48%) were complicated with bacteremia. As the TG18 severity grading increased, the frequency of bacteremia increased (Grade I, 35% [59/171]; Grade II, 59% [48/82]; Grade III, 74% [42/57]; P <0.001). Agreement with the TG18 diagnostic criteria (unfulfilled, suspected, or definite) was not different between patients with and without bacteremia; however, 36% (14/39) of the patients with "unfulfilled" criteria were complicated with bacteremia.

Conclusions: As the severity of acute cholangitis increased, the frequency of bacteremia increased; however, the incidence of bacteremia was high even in mild cases and cases that did not meet the TG18 diagnostic criteria. Blood cultures should be collected regardless of the severity of acute cholangitis for patients who visit the emergency department.