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Constructing Mutants in Serotype 1 Streptococcus pneumoniae strain 519/43
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Novel type of Streptococcus pneumoniae causing multidrug-resistant acute otitis media in children

Qingfu Xu1, Michael E Pichichero, Janet R Casey

  • 1University of Rochester School of Medicine and Dentistry, Rochester, New York, USA.

Emerging Infectious Diseases
|April 1, 2009
PubMed

Insights

A Streptococcus pneumoniae "superbug" resistant to all drugs for childhood ear infections was discovered. Further analysis revealed multiple drug-resistant strains, predominantly serotype 19A, highlighting a growing public health concern.

Area of Science:

  • Microbiology
  • Genetics
  • Public Health

Background:

  • Acute otitis media (AOM) in children is frequently caused by Streptococcus pneumoniae.
  • Emergence of antimicrobial resistance in S. pneumoniae poses a significant challenge to AOM treatment.
  • A novel 19A S. pneumoniae strain (Legacy strain) resistant to all FDA-approved drugs for AOM was recently identified.

Purpose of the Study:

  • To characterize additional S. pneumoniae isolates from children with AOM.
  • To identify the prevalence of multidrug-resistant (MDR) strains and their serotypes.
  • To investigate the genetic relatedness of MDR strains.

Main Methods:

  • Multilocus sequence typing (MLST) was performed on 40 S. pneumoniae isolates from children with AOM.
  • Serotyping was conducted to determine the capsular type of the isolates.
  • Genetic relatedness analysis was used to cluster strains based on MLST data.

Main Results:

  • 16% of isolates were serotype 19A, and 23% were multidrug-resistant.
  • 88% of MDR strains (8 out of 9) were serotype 19A, including the Legacy strain with a new sequence type (ST-2722).
  • ST-2722 is genetically related to ST-156, with MDR strains linked to ST-156 expressing various serotypes (9V, 14, 11A, 15C, 19F).

Conclusions:

  • Serotype 19A is a significant cause of multidrug-resistant Streptococcus pneumoniae in children with AOM.
  • The emergence of new sequence types, like ST-2722, associated with MDR strains is a concern.
  • Continued surveillance and characterization of resistant S. pneumoniae strains are crucial for public health.

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