Trends in US Hospital Stays for Listeriosis in Infants.

BACKGROUND AND OBJECTIVES Although listeriosis is rare in infants, it is common for young infants with suspected serious bacterial infection to be treated empirically with agents selected, in part, for their activity against Listeria monocytogenes. Our objectives were to describe the recent epidemiology of hospital discharges for listeriosis among infants in the United States and to precisely estimate the incidence of listeriosis according to infant age and meningitis status. METHODS We generated national estimates for listeriosis discharges in each of the 6 years for which samples were available in the Kids' Inpatient Database during the period 1997-2012. We used random-effects models to pool descriptive information and population rates across study years. RESULTS The cumulative number of US hospital discharges for listeriosis in infants was 344 (95% confidence interval [CI]: 290-397) over the 6 study years. The pooled annual incidence rate in infants (per 100,000 births) was 1.41 (95% CI: 1.01-1.80) after accounting for marked fluctuation in annual rates (range: 0.66-1.86; I2=79.3%). Discharges for listeriosis without meningitis were particularly rare after the first week of life. Our models predicted only 2.7 (95% CI: 1.1-4.2) and 1.8 (95% CI: 0.0-3.6) such discharges per year in infants admitted at ages 7 to 28 days and 29 to 364 days, respectively. CONCLUSIONS From the perspective of providing coverage against listeriosis, the routine practice of including ampicillin in the empirical treatment of febrile infants should be reevaluated for those older than 1 week without clinical evidence of meningitis.