Allelic variations of an internal locus of the pyruvate oxidase gene spxB among pneumococci isolated in Germany

R. R. Reinert, A. Al-Lahham, A. Marek, R. Lütticken, B. Spellerberg


Background: Streptococcus pneumoniae is well known as a causative agent of severe infectious diseases, such as pneumonia and meningitis. Hydrogen peroxide is produced by the pneumococcus through the pyruvate oxidase leading to a bactericidal effect on other inhabitants of the upper respiratory tract, such as H. influenzae, and may therefore play a major role in the pathogenesis of pneumococcal infection. The objective of this study was to identify the allelic variations of an internal locus of the pyruvate oxidase gene (spxB) among strains responsible for different pneumococcal infections. Methods: A total of 188 isolates of S. pneumoniae were chosen from the strain collection of the German National Reference Center for Streptococci. These strains originated from different types of infection. Sites of isolation were as follows: blood (n = 36), CSF (35), nasopharynx (45), eye (15), bronchial alveolar lavage (15), ear (21); 9 strains came from other sources, and 12 from the American Type Culture Collection representing internationally predominant clones. Primers hybridizing in a conserved region of the spxB gene (accession number L39074) at positions 908- 928 (forward primer) and 1442-1462 (reverse primer) were selected for PCR amplification. PCR was performed by standard methods. PCR products were sequenced using an ABI-Prism 310 sequencer. All strains were serotyped by the Neufeld Quellung reaction. Results: Of the 188 pneumococcal strains, thus far the spxB-locus was sequenced in 61 strains (32.4%). Thirty-four pneumococcal strains were penicillin nonsusceptible (serotype 23F). The PCR-product contained 464 bp (position spxB 950-1413). The sequence analysis of this product showed 14 different sequence types (ST) among the pneumococcal isolates. Each ST contained at least 10 point mutations in the spxB locus compared to the published sequence of the S. pneumoniae R6 strain. The sequence analysis of the 23F penicillin nonsusceptible pneumococci (34 strains) showed only 3 different ST; ST 1 (2.9%), ST 2 (85.29%) and ST 3 (11.76%) of the 23F strains. The sequence analysis of the 61 isolates analyzed so far showed no correlation between the ST and type of pneumococcal infection.

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11th European Congress of Clinical Microbiology and Infectious Diseases
    • ECCMID 11th (2001)