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|Title:||Specific growth conditions induce a Streptococcus pneumoniae non-mucoidal, small colony variant and determine the outcome of its co-culture with Haemophilus influenzae|
|Citation:||Pathogens and disease, 2018; 76(7)|
|Publisher:||Oxford University Press|
|Alexandra Tikhomirova, Claudia Trappetti, Alistair J Standish, Yiwen Zhou James Breen, Stephen Pederson, Peter S Zilm, James C Paton, Stephen P Kidd|
|Abstract:||Haemophilus influenzae and Streptococcus pneumoniae are known aetiologic agents of chronic otitis media, frequently as a multispecies infection. In this study, we show that the outcome of H. influenzae/S. pneumoniae interactions is dependent on the nutrient source. In continuous culture containing chemically defined media with lactose, S. pneumoniae was non-viable in mono-culture, and in co-culture remained non-viable until 288 h. With glucose, S. pneumoniae became non-viable in mono-culture, but uniquely existed in 3 distinct states in co-culture: parental cells (until 24 h), a dormant state until 336 h and its re-emergence as a non-mucoidal, small colony variant (SCV). The S. pneumoniae SCV was stable and whole genome sequencing showed three major single nucleotide polymorphisms in the SCV cells-cap3A (capsule biosynthesis pathway), fpg (DNA glycosylase of the DNA repair mechanism) and glutamate-5-kinase. Previously, fpg mutants have shown increased mutator rates, permitting bacterial survival against host-generated stresses. Transcriptomics showed these SCV cells up-regulated sugar transporters and toxin/antitoxin systems. An animal model revealed a reduced survival in the lungs and ear by SCV cells. This is the first study documenting the effect of carbon source and the development of a distinct S. pneumoniae cell type during H. influenzae/S. pneumoniae interactions.|
|Keywords:||Streptococcus pneumoniae; Haemophilus influenzae; co-infection; small colony variants; bacterial pathogenesis; molecular adaptation; dormant|
|Rights:||© FEMS 2018. All rights reserved.|
|Appears in Collections:||Environment Institute publications|
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