Shorter antibiotic duration tied to higher mortality in infants with E. coli bacteremia

Shorter course of antibiotics was associated with higher mortality rates in infants with Escherichia coli (E. coli) bacteremia who did not undergo a cerebrospinal fluid (CSF) evaluation compared with longer antibiotic courses, according to a recent study presented at PAS 2024.

“E. coli is a common cause of bacteremia and meningitis in preterm infants … However, the optimal duration of antibiotic therapy in infants with E. coli bacteremia when CSF evaluation is not obtained is unknown, leading to variations in practice,” said Dr Ashley Stark from Duke University School of Medicine in Durham, North Carolina, US.

“Currently, there are no guidelines or formal recommendations regarding [antibiotic therapy] duration,” she noted.

Using data from the Pediatrix Medical Group Database between 1997 and 2020, the researchers conducted a retrospective study involving 983 infants with gram-negative rod bacteremia due to E. coli who received antibiotic treatment within the first 2 days of the index culture. Antibiotic treatment duration was categorized as <14 days (n=433), 14–21 days (n=296), and >21 days (n=254). [Stark A, et al, PAS 2024]

Infants who received a short course of antibiotics for <14 days had a significantly higher 30-day mortality rate than those who received a long course of antibiotics for 14–21 and >21 days (34 percent vs 5 percent and 8 percent, respectively; p<0.001).

Shorter treatment duration was also associated with a significant increase in inhospital mortality rate compared with longer durations (36 percent vs 8 percent [14–21 days] and 14 percent [>21 days]; p<0.001).

Significantly lower rates of the composite outcome of recurrence of infection and death were also observed in the short-course group over the long-course group (39 percent vs 12 percent [14–21 days] and 18 percent [>21 days]; p<0.001).

After adjusting for gestational age, postmenstrual age, sex, and clinical severity, longer duration of antibiotic treatment was consistently associated with lower rates of 30-day mortality (odds ratios [ORs], 0.06 and 0.09 [14–21 and >21 days, respectively]) and inhospital mortality (ORs, 0.1 and 0.16) compared with shorter treatment duration of <14 days.

“Notably, infants who received 14–21 days of antibiotic therapy had the best overall outcomes,” Stark said.

Stark acknowledged that the study had several limitations, owing to E. coli bacteremia as a rare event, and despite the vast number of infants included in the paediatrics database, the study population is small, with an even smaller number of infants reaching the defined outcome of death.

“Overall, a shorter duration of antibiotic therapy is unlikely to improve outcomes, and potentially lead to increased mortality,” said Stark.

“In preterm and term infants with E. coli bacteremia in which a CSF evaluation was not obtained, a minimum duration of 14 days for antibiotic therapy should be considered,” she suggested.