Use of the 10-valent pneumococcal Haemophilus influenzae protein D conjugate vaccine (PHiD-CV10) in an Australian Indigenous paediatric population does not alter the prevalence of nontypeable Haemophilus influenzae without the protein D gene

Abstract

BackgroundNontypeable Haemophilus influenzae (NTHi) is one of the main respiratory pathogens associated with otitis media and lung infections in Australian Indigenous children. PHiD-CV10, the 10-valent pneumococcal conjugate vaccine containing H. influenzae protein D was used in the Northern Territory infant vaccination schedule for two years from October 2009. MethodsNTHi isolates from nasopharyngeal and ear discharge samples collected before, during and after the PHiD-CV10 era were screened for the hpd gene by PCR. Target amplicon sequence, extracted from available genomic sequence data, was analysed to identify variability in this region. ResultsThere was no statistically significant difference in the proportion of hpd#3-PCR negative isolates from each era; overall 7% and 6% of nasopharyngeal and ear discharge isolates were negative, respectively. The nucleotide sequence data supported the hpd-PCR findings; truncations of the hpd gene precluding amplification and presumably expression of protein D were observed in approximately 7% of available genomes. ConclusionsIn the Northern Territory of Australia, a population at high risk of NTHi-associated infection, PHiD-CV10 use did not select for hpd-PCR negative isolates.