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Mohale T, Wolter N, Allam M, Nzenze SA, Madhi SA, du Plessis M, von Gottberg A. Genomic differences among carriage and invasive nontypeable pneumococci circulating in South Africa. Microb Genom 2019; 5. [PMID: 31617841 PMCID: PMC6861859 DOI: 10.1099/mgen.0.000299] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Most pneumococci express a polysaccharide capsule, a key virulence factor and target for pneumococcal vaccines. However, pneumococci showing no serological evidence of capsule expression [nontypeable pneumococci (NTPn)] are more frequently isolated from carriage studies than in invasive disease. Limited data exist about the population structure of carriage NTPn from the African continent. We aimed to characterize carriage NTPn and compare them to previously described invasive NTPn. Carriage and invasive NTPn isolates were obtained from South African cross-sectional studies (2009 and 2012) and laboratory-based surveillance for invasive pneumococcal disease (2003–2013), respectively. Isolates were characterized by capsular locus sequence analysis, multilocus sequence typing, antimicrobial non-susceptibility patterns and phylogenetic analysis. NTPn represented 3.7 % (137/3721) of carriage isolates compared to 0.1 % (39/32 824) of invasive isolates (P<0.001), and 24 % (33/137) of individuals were co-colonized with encapsulated pneumococci. Non-susceptibility to cotrimoxazole [84 % (112/133) vs 44 % (17/39)], penicillin [77 % (102/133) vs 36 % (14/39)], erythromycin [53 % (70/133) vs 31 % (12/39)] and clindamycin [36 % (48/133) vs 18 % (7/39)] was higher (P=0.03) among carriage than invasive NTPn. Ninety-one per cent (124/137) of carriage NTPn had complete deletion of the capsular locus and 9 % (13/137) had capsule genes, compared to 44 % (17/39) and 56 % (22/39) of invasive NTPn, respectively. Carriage NTPn were slightly less diverse [Simpson’s diversity index (D)=0.92] compared to invasive NTPn [D=0.97]. Sixty-seven per cent (92/137) of carriage NTPn belonged to a lineage exclusive to NTPn strains compared to 23 % (9/39) of invasive NTPn. We identified 293 and 275 genes that were significantly associated with carriage and invasive NTPn, respectively. NTPn isolates detected in carriage differed from those causing invasive disease, which may explain their success in colonisation or in causing invasive disease.
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Affiliation(s)
- Thabo Mohale
- Centre for Respiratory Diseases and Meningitis, National Institute for Communicable Diseases, National Health Laboratory Service, Johannesburg, South Africa.,Clinical Microbiology and Infectious Diseases, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Nicole Wolter
- Clinical Microbiology and Infectious Diseases, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.,Centre for Respiratory Diseases and Meningitis, National Institute for Communicable Diseases, National Health Laboratory Service, Johannesburg, South Africa
| | - Mushal Allam
- Sequencing Core Facility, National Institute for Communicable Diseases, National Health Laboratory Service, Johannesburg, South Africa
| | - Susan A Nzenze
- Department of Science and Technology/National Research Foundation: Vaccine Preventable Diseases Research Chair, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.,Medical Research Council: Respiratory and Meningeal Pathogens Research Unit, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Shabir A Madhi
- Department of Science and Technology/National Research Foundation: Vaccine Preventable Diseases Research Chair, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.,Medical Research Council: Respiratory and Meningeal Pathogens Research Unit, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Mignon du Plessis
- Clinical Microbiology and Infectious Diseases, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.,Centre for Respiratory Diseases and Meningitis, National Institute for Communicable Diseases, National Health Laboratory Service, Johannesburg, South Africa
| | - Anne von Gottberg
- Clinical Microbiology and Infectious Diseases, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.,Centre for Respiratory Diseases and Meningitis, National Institute for Communicable Diseases, National Health Laboratory Service, Johannesburg, South Africa
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Invasive Disease Caused Simultaneously by Dual Serotypes of Streptococcus pneumoniae. J Clin Microbiol 2017; 56:JCM.01149-17. [PMID: 29118167 DOI: 10.1128/jcm.01149-17] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Accepted: 10/28/2017] [Indexed: 11/20/2022] Open
Abstract
There are at least 98 known pneumococcal serotypes. Invasive pneumococcal disease (IPD) is usually caused by a single serotype, and dual-serotype IPD is rare. To assess factors associated with dual-serotype IPD, patient information obtained through laboratory-based surveillance for IPD from 2005 through 2014 in South Africa was reviewed. Genomes of isolate pairs from coinfected individuals were sequenced to determine their molecular characteristics. For 30 (91%) of 33 patients with dual serotypes, one or both isolates were a pneumococcal conjugate vaccine (PCV13) serotype. Dual-serotype IPD was associated with children <5 years of age (adjusted odds ratio [aOR], 4.7; 95% confidence interval [95% CI], 1.8 to 11.7), underlying illness (other than HIV) (aOR, 2.8; 95% CI, 1.1 to 6.6) and death (aOR, 2.5; 95% CI, 1.08 to 6.09). For each coinfecting pair, isolates were genotypically unrelated, and their genotypes were common among isolates of the same serotype in South Africa. Of 701 accessory genes identified among dual-serotype IPD isolates, four were common between isolate pairs. Coinfecting isolate pairs had different genotypic backgrounds. The association of dual serotypes with death warrants increased awareness of IPD coinfection caused by two or more serotypes.
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