A Retrospective Study of the Impact of Pneumococcal Conjugate Vaccine-13 Immunization in a Northern Israel Hospital.

Background: The introduction of pneumococcal conjugate vaccine-13 (PCV-13) has reduced the burden of invasive pneumococcal disease.

Objectives: To characterize true positive blood cultures of children who presented to our hospital following implementation of the PCV-13 vaccine.

Methods: A retrospective study was conducted on positive blood cultures of children presenting with fever from 2010-2017. Subjects were divided into two age groups: a younger group 3-36 months and an older group 3-18 years. Patients were classified as either having or not having a focus of infection at the time of their bacteremia. Pneumococcal isolates were typed at Israel's Streptococcal Reference Laboratory.

Results: The samples included 94 true positive blood cultures. Focal infection with concomitant bacteremia was more common than bacteremia without a focus both overall: 67/94 (71%) vs. 27/94 (28.7%), P <0.001 as well as in the two groups: 32/48 (66%) vs. 16/48 (33%), P = 0.02 in the younger group and 35/46 (76%) vs. 11/46 (24%), P = 0.001 in the older group. Streptococcus pneumoniae was the most common pathogen overall, 27/94 (29%), and in the younger group, 21/48 (44%), but rare in the older group, 6/46 (13%). In the latter, Brucella species predominated, 12/46 (26%), along with Staphylococcus aureus 12/46 (26%).

Conclusions: Our findings are consistent with other studies reporting decreased pneumococcal bacteremia, bacteremia primarily accompanying focal infection, and changing etiological agents among PCV-13-vaccinated children. Brucella species was prominent in older children with osteoarticular infections. Ongoing surveillance is warranted to better understand the implications of PCV-13.