title: Two cases of serotypeable and non-serotypeable variants of Streptococcus pneumoniae detected simultaneously during invasive disease.
abstract: More than 94 serotypes of Streptococcus pneumoniae have been described to date, however the majority of disease is caused by approximately 20 serotypes. Some pneumococci do not react with commercially available antisera used for serotyping and are thus regarded as non-serotypeable (NT). These pneumococci are commonly isolated during carriage studies and very rarely cause invasive disease. Colonization may occur with more than one serotype however disease with more than one serotype is rarely detected. Thus there are limited data describing cases of pneumococcal disease caused by more than one isolate.
  
  
  
  In two cases of invasive pneumococcal disease in South Africa, a non-serotypeable and a serotypeable isolate were co-detected during routine serotyping. A serotype 1 and 18C isolate were each co-detected with a non-serotypeable isolate in 2009 (case A) and 2010 (case B), from cerebrospinal fluid and blood, respectively. Both patients were 10-14 years old. For case A, the serotypeable isolate could not be obtained due to low representation in the mixed culture. Using electron microscopy we confirmed lack of capsule for the non-serotypeable isolates. Comparison of the case A non-serotypeable isolate with a serotype 1 genome revealed only the presence of the rhamnose biosynthesis genes (rmlA, B, C and D) in the capsular locus, all other capsular genes were absent. Nonetheless it had a multilocus sequence type (ST) associated with serotype 1 (ST217 and ribosomal ST3462) and its core genome clustered with other ST217 isolates. The case B non-serotypeable isolate had all serotype 18C capsular genes except for variation in the wchA and wze genes, compared to the 18C isolate. Both case B isolates were ST9817 and their core genomes were identical.
  
  
  
  The ability of pneumococci to alter capsule production is a potential vaccine escape mechanism and therefore non-serotypeable pneumococci should be monitored as such organisms may increase under vaccine pressure.
authors.affiliation: Centre for Respiratory Diseases and Meningitis (CRDM), National Institute for Communicable Diseases (NICD), a division of the National Health Laboratory Service, Johannesburg, South Africa. kedibonen@nicd.ac.za.|School of Pathology, University of the Witwatersrand, Johannesburg, South Africa. kedibonen@nicd.ac.za.
authors.forename: Kedibone M
authors.initials: KM
authors.lastname: Ndlangisa
authors.affiliation: Centre for Respiratory Diseases and Meningitis (CRDM), National Institute for Communicable Diseases (NICD), a division of the National Health Laboratory Service, Johannesburg, South Africa.|School of Pathology, University of the Witwatersrand, Johannesburg, South Africa.
authors.forename: Mignon
authors.initials: M
authors.lastname: du Plessis
authors.affiliation: Centre for Respiratory Diseases and Meningitis (CRDM), National Institute for Communicable Diseases (NICD), a division of the National Health Laboratory Service, Johannesburg, South Africa.
authors.forename: Mushal
authors.initials: M
authors.lastname: Allam
authors.affiliation: Centre for Respiratory Diseases and Meningitis (CRDM), National Institute for Communicable Diseases (NICD), a division of the National Health Laboratory Service, Johannesburg, South Africa.|School of Pathology, University of the Witwatersrand, Johannesburg, South Africa.
authors.forename: Nicole
authors.initials: N
authors.lastname: Wolter
authors.affiliation: Centre for Respiratory Diseases and Meningitis (CRDM), National Institute for Communicable Diseases (NICD), a division of the National Health Laboratory Service, Johannesburg, South Africa.|School of Pathology, University of the Witwatersrand, Johannesburg, South Africa.
authors.forename: Thabo
authors.initials: T
authors.lastname: Mohale
authors.affiliation: Centre for Respiratory Diseases and Meningitis (CRDM), National Institute for Communicable Diseases (NICD), a division of the National Health Laboratory Service, Johannesburg, South Africa.
authors.forename: Linda
authors.initials: L
authors.lastname: de Gouveia
authors.affiliation: Centre for Emerging and Zoonotic Diseases, National Institute for Communicable Diseases (NICD), a division of the National Health Laboratory Service, Johannesburg, South Africa.
authors.forename: Monica
authors.initials: M
authors.lastname: Birkhead
authors.affiliation: Hubert Department of Global Health, Rollins School of Public Health, and Division of Infectious Diseases, School of Medicine, Emory University, Atlanta, GA, USA.
authors.forename: Keith P
authors.initials: KP
authors.lastname: Klugman
authors.affiliation: Centre for Respiratory Diseases and Meningitis (CRDM), National Institute for Communicable Diseases (NICD), a division of the National Health Laboratory Service, Johannesburg, South Africa.|School of Pathology, University of the Witwatersrand, Johannesburg, South Africa.
authors.forename: Anne
authors.initials: A
authors.lastname: von Gottberg
mesh_terms: D000293:Adolescent; D002648:Child; D006801:Humans; D008297:Male; D011008:Pneumococcal Infections / Q000175:diagnosis / Q000382:microbiology*; D012703:Serotyping; D013296:Streptococcus pneumoniae / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*
keywords: Mixed culture; Non-serotypeable; Pneumococcus; Serotype 1; Serotype 18C; South Africa; cpsE; wchA