title: Emergence of Multidrug-Resistant Pneumococcal Serotype 35B among Children in the United States.
abstract: Streptococcus pneumoniaeserotype 35B is a nonvaccine serotype associated with high rates of penicillin nonsusceptibility. An increase in the proportion of multidrug-resistant (MDR) 35B isolates has recently been reported. The genetic events contributing to the emergence of MDR serotype 35B are unknown. The sequence type (ST) composition of 78 serotype 35B isolates obtained from pediatric patients with invasive pneumococcal disease from 1994 to 2014 and 48 isolates from pediatric patients with otitis media (noninvasive) from 2011 to 2014 was characterized by multilocus sequence typing (MLST). The most common STs were ST558 (69.2%), ST156 (10.3%), and ST452 (3.8%). Two major clonal complexes (CC), CC558 and CC156, were identified by eBURST analysis. Overall, 91% (71/78) of isolates were penicillin nonsusceptible and 16.7% (13/78) were MDR. Among all invasive serotype 35B isolates, MDR isolates increased significantly, from 2.9% (1/35) to 27.9% (12/43) (P= 0.004), after the 13-valent pneumococcal conjugate vaccine (PCV13) was introduced. All CC156 isolates were identified after the introduction of PCV13 (0/35 [0%] before versus 9/43 [20.9%] after;P= 0.003) and were MDR. All CC156 isolates had similar antimicrobial susceptibility patterns; in contrast, high variability in antimicrobial susceptibility was observed among CC558 isolates. The distributions of CC558 and CC156 among invasive and noninvasive isolates were not different. The increased prevalence of MDR serotype 35B after the introduction of PCV13 was directly associated with the emergence of ST156. Genotyping suggests that capsular switching has occurred between MDR vaccine serotypes belonging to ST156 (e.g., 9V, 14, and 19A) and serotype 35B.
authors.affiliation: Department of Pediatrics of Baylor College of Medicine, Houston, Texas, USA liset.olarte@alumni.bcm.edu khulten@bcm.edu.
authors.forename: Liset
authors.initials: L
authors.lastname: Olarte
authors.affiliation: Department of Pediatrics of Baylor College of Medicine, Houston, Texas, USA.
authors.forename: Sheldon L
authors.initials: SL
authors.lastname: Kaplan
authors.affiliation: Ohio State University College of Medicine, Columbus, Ohio, USA.
authors.forename: William J
authors.initials: WJ
authors.lastname: Barson
authors.affiliation: University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA.
authors.forename: José R
authors.initials: JR
authors.lastname: Romero
authors.affiliation: Children's Hospital of Pittsburgh of the University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, USA.
authors.forename: Philana Ling
authors.initials: PL
authors.lastname: Lin
authors.affiliation: Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA.
authors.forename: Tina Q
authors.initials: TQ
authors.lastname: Tan
authors.affiliation: University of Southern California School of Medicine, Los Angeles, California, USA.
authors.forename: Jill A
authors.initials: JA
authors.lastname: Hoffman
authors.affiliation: Rady Children's Hospital San Diego, San Diego, California, USA.
authors.forename: John S
authors.initials: JS
authors.lastname: Bradley
authors.affiliation: Wake Forest School of Medicine, Winston-Salem, North Carolina, USA.
authors.forename: Laurence B
authors.initials: LB
authors.lastname: Givner
authors.affiliation: Department of Pediatrics of Baylor College of Medicine, Houston, Texas, USA.
authors.forename: Edward O
authors.initials: EO
authors.lastname: Mason
authors.affiliation: Department of Pediatrics of Baylor College of Medicine, Houston, Texas, USA liset.olarte@alumni.bcm.edu khulten@bcm.edu.
authors.forename: Kristina G
authors.initials: KG
authors.lastname: Hultén
mesh_terms: D000293:Adolescent; D016667:Bacterial Capsules / Q000235:genetics; D002648:Child; D002675:Child, Preschool; D024901:Drug Resistance, Multiple, Bacterial; D005260:Female; D005838:Genotype; D006801:Humans; D007223:Infant; D008297:Male; D058885:Multilocus Sequence Typing; D011008:Pneumococcal Infections / Q000453:epidemiology* / Q000382:microbiology*; D022242:Pneumococcal Vaccines / Q000008:administration & dosage / Q000276:immunology; D015995:Prevalence; D011446:Prospective Studies; D065288:Serogroup; D013296:Streptococcus pneumoniae / Q000145:classification* / Q000187:drug effects* / Q000302:isolation & purification; D014481:United States / Q000453:epidemiology
chemical_list: C538862:13-valent pneumococcal vaccine; D022242:Pneumococcal Vaccines
keywords: Streptococcus pneumoniae; multidrug resistance; otitis media; pneumococcal disease; pneumococcal vaccine; pneumococcus; serotype 35B