Measuring the effects of pneumococcal conjugate vaccine (PCV7) on Streptococcus pneumoniae carriage and antibiotic resistance: The Palestinian-Israeli Collaborative Research (PICR).

Vaccine. 2015 Jan 12. pii: S0264-410X(15)00004-3. doi: 10.1016/j.vaccine.2015.01.003. [Epub ahead of print]

Measuring the effects of pneumococcal conjugate vaccine (PCV7) on Streptococcus pneumoniae carriage and antibiotic resistance: The Palestinian-Israeli Collaborative Research (PICR).

Daana M1, Rahav G2, Hamdan A3, Thalji A4, Jaar F5, Abdeen Z6, Jaber H2, Goral A7, Huppert A8, Raz M9, Regev-Yochay G10; for the PICR study group.

Author information

Abstract

BACKGROUND:

The Palestinian-Israeli Collaborative Research (PICR) cross-conflict setting provided a unique opportunity to study overall and indirect effects of pneumococcal conjugate vaccine (PCV7), in two closely related Palestinian populations governed by two distinct health authorities with distinct vaccination policies. Here, PCV7 effects on pneumococcal carriage, serotype distribution and antibiotic resistance are reported.

METHODS:

Annual cross-sectional surveys of pneumococcal carriage were performed during 2009-2011 among Palestinian children (≤5 years) (a) under Palestinian-Authority (PA) health policy (Ramallah, Nablus and Bethlehem), where PCV7 was unlicensed (b) under Israeli health policy (East-Jerusalem (EJ)) where PCV7 was rapidly implemented from July 2009. Clinical data were collected, pneumococci identified and characterized for antibiotic susceptibilities and serotype. Analyses included multivariate logistic models with an interaction term for PCV7-effect.

RESULTS:

Altogether, 2755 children from PA (n=1772) and EJ (n=983) were enrolled, of which ∼30% were pneumococcal carriers. While overall carriage was not affected by vaccination policy, carriage of vaccine-type (VT7) strains decreased from 52% to 22% (p<0.001) in EJ, where PCV was implemented, but not in PA. This was accompanied by an increase in non-VT13 strains from 34% to 65% (p<0.001) in EJ, but not in PA. Furthermore, within two years post-PCV7 introduction, proportion of multi-drug resistant strains, which was initially 23% in both populations, decreased significantly in EJ, to 10%, while simultaneously it increased in PA to 33% (p<0.001). Similar trends were observed for resistance to most antibiotic groups. The proportion of resistant isolates among non-VT13 strains did not change during the study period.

CONCLUSIONS:

The unique study design distinguishes secular and seasonal effects from true vaccine effects. While PCV7 did not affect overall pneumococcal carriage rate, VT7 strains, many of which were antibiotic resistant decreased and were replaced by non-VT13 strains, which were mostly not antibiotic resistant, resulting in a net decrease in antibiotic resistance.

Copyright © 2015. Published by Elsevier Ltd.

KEYWORDS:

Antibiotic resistance; PCV7 effects; Pneumococcal carriage; Population-based study

PMID: 25593104 [PubMed - as supplied by publisher]