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Title: The nonserotypeable pneumococcus: phenotypic dynamics in the era of anticapsular vaccines.
Authors: Marsh, R
Smith-Vaughan, H
Hare, K M
Binks, M
Kong, F
Warning, J
Gilbert, G L
Morris, P
Leach, A J
Affiliation: Menzies School of Health Research, Royal Darwin Hospital, Darwin, Northern Territory, Australia.
Issue Date: Mar-2010
Citation: Journal of clinical microbiology 2010-03; 48(3): 831-5
Abstract: Nonserotypeable pneumococci (NSP) are commonly carried by Australian Indigenous children in remote communities. The purpose of this study was to characterize carriage isolates of NSP from Indigenous children vaccinated with the seven-valent pneumococcal conjugate vaccine (PCV7) and to use these data to guide decisions on reporting of NSP. A total of 182 NSP were characterized by BOX typing, antibiogram analysis, and multilocus sequence typing (MLST) of common BOX types. NSP positive for the wzg capsule gene were analyzed by a multiplex PCR-based reverse line blot hybridization assay (mPCR/RLB-H) targeting capsule genes to determine the serotype. Among 182 NSP, 49 BOX types were identified. MLST of 10 representative isolates found 7 STs, including ST448 (which accounted for 11% of NSP). Non-penicillin susceptibility was evident in 51% of the isolates. Pneumococcal wzg sequences were detected in only 23 (13%) NSP, including 10 that contained an approximately 1.2-kb insert in the region. mPCR/RLB-H identified serotype 14 wzy sequences in all 10 NSP, and 1 also contained a serotype 3-specific wze sequence. Among the remaining 13 wzg-positive NSP, few belonged to the serotypes represented in PCV7. It appears that most NSP identified in Australian Indigenous children are from a true nonencapsulated lineage. Few NSP represented serotypes in PCV7 that suppress capsular expression. High rates of carriage and penicillin resistance and the occasional presence of capsule genes suggest a role for NSP in the maintenance and survival of capsulated pneumococci. To avoid the inflation of pneumococcal carriage and antibiotic resistance rates, in clinical trials, we recommend separate reporting of rates of capsular strains and NSP and the exclusion of data for NSP from primary analyses.
DOI: 10.1128/JCM.01701-09
Type: Journal Article
Research Support, Non-U.S. Gov't
Subjects: Australia
Bacterial Capsules
Bacterial Proteins
Bacterial Typing Techniques
Carrier Proteins
Carrier State
Child, Preschool
DNA Fingerprinting
Heptavalent Pneumococcal Conjugate Vaccine
INDEL Mutation
Infant, Newborn
Molecular Epidemiology
Penicillin Resistance
Pneumococcal Infections
Pneumococcal Vaccines
Population Groups
Streptococcus pneumoniae
Appears in Collections:NT Health digital library

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