Background: No information is available in Israel on the anticipated changes in OB incidence in infants/young children vaccinated with pneumococcal conjugate vaccines (PCVs).
Objectives: To characterize the epidemiological, microbiological and clinical picture and outcome of OB among febrile infants/children aged 3-36 months in southern Israel, before and after the introduction of PCVs in the national immunization plan.
Patients and methods: A retrospective study enrolling all infants/ young children diagnosed at Pediatric Emergency Room (PER) with fever (>380C) without source, discharged and reported with a positive blood culture growing a true pathogen.
Results: Of the 453 true bacteremias reported at PER, 89 were defined as OB. Overall OB rate was 0.22%; a significant decrease was recorded in OB rates during the study years, with the highest rate during 2005 (0.34%) and the lowest during 2011 (0.15%). The number of OB cases decreased in the post-PCV vaccination (2010-2012) compared with the pre-vaccination period (2005-2009) from 66/22,256 (0.3%) to 23/13,213 (0.17) cases (P=0.03). The most frequently isolated OB pathogens were SP, Streptococcus viridans spp, Kingella kingae and Salmonella spp. (39.3, 10.1, 9 and 6.7%, respectively); Enterobacteriaceae spp. were isolated in 10 (11.2%) cases. No changes were recorded in the number of SP-OB cases while the number of K. kingae isolates decreased significantly (P=0.047). None of the SP serotypes isolated during 2011-2012 belonged to PCV13. A significant increase in the non-PCV13 serotypes was recorded during 2011-2012 (3/3, 100% vs. 7/32, 21.9%, P=0.01). 60/89 (67.4%) of the OB patients had a F/U visit; a new infectious focus was detected in 9 patients. Conclusions: 1. The OB rates decreased significantly following PCVs' introduction; 2. SP was the main pathogen isolated in OB, but in lower percentages compared with the medical literature; 3. PCV13 serotypes were eliminated as a cause of OB during 2011-2012.
