Emergence of Respiratory Streptococcus agalactiae Isolates in Cystic Fibrosis Patients

Streptococcus agalactiae is a well-known pathogen for neonates and immunocompromized adults. Beyond the neonatal period, S. agalactiae is rarely found in the respiratory tract. During 2002–2008 we noticed S. agalactiae in respiratory secretions of 30/185 (16%) of cystic fibrosis (CF) patients. The median age of these patients was 3–6 years older than the median age CF patients not harboring S. agalactiae. To analyze, if the S. agalactiae isolates from CF patients were clonal, further characterization of the strains was achieved by capsular serotyping, surface protein determination and multilocus sequence typing (MLST). We found a variety of sequence types (ST) among the isolates, which did not substantially differ from the MLST patterns of colonizing strains from Germany. However serotype III, which is often seen in colonizing strains and invasive infections was rare among CF patients. The emergence of S. agalactiae in the respiratory tract of CF patients may represent the adaptation to a novel host environment, supported by the altered surfactant composition in older CF patients

Molecular characterization of 19 unique <i>S. agalactiae</i> strains from CF patients.

*<p>Nontypable.</p

Molecular characterization of 72 colonizing <i>S. agalactiae</i> strains from the urogenital and gastrointestinal tract.

<p>Molecular characterization of 72 colonizing <i>S. agalactiae</i> strains from the urogenital and gastrointestinal tract.</p

Clinical characteristics of <i>S. agalactiae</i> (GBS) positive cystic fibrosis patients.

<p>Clinical characteristics of <i>S. agalactiae</i> (GBS) positive cystic fibrosis patients.</p

Figure 2

<p>A: Association between surface proteins and sequence types. For each sequence type found in either respiratory strains from CF patients or colonizing strains, the number of isolates and the surface proteins of these strains are shown. Genes coding for alpha C, Epsilon, Rib or Alp2/3 were detected in the vast majority of strains, only five isolates failed to generate a PCR product with the specific primers. B: Association between serotypes and sequence types. For each sequence type found in either respiratory strains from CF patients or colonizing strains, the number of isolates and the serotypes of these strains are shown.</p

Population structure of <i>Streptococcus agalactiae</i>: Depicted are the three major recognized burst groups of <i>S. agalactiae</i>.

<p>Sequence types that vary by one allele in their MLST profiles (single locus variants) are arranged in circles around the primary founder sequence type. The population structure diagram was created based on the <i>S. agalactiae</i> MLST database as found under: <a href="http://eburst.mlst.net" target="_blank">http://eburst.mlst.net</a>. Sequence types present in our collection of colonizing strains are depicted as closed circles, sequence types found in the <i>S. agalactiae</i> strains form CF patients are shown as open squares. The major clonal complexes (CC) are indicated in the picture.</p