TY - JOUR AU - Ktari, Sonia AU - Ben Ayed, Nour El Houda AU - Maalej, Sonda AU - Mnif, Basma AU - Rhimi, Faouzia AU - Hammami, Adnene PY - 2021/05/31 Y2 - 2024/03/28 TI - Clinical optochin resistant Streptococcus pneumoniae and Streptococcus pseudopneumoniae strains in Tunisia JF - The Journal of Infection in Developing Countries JA - J Infect Dev Ctries VL - 15 IS - 05 SE - Original Articles DO - 10.3855/jidc.13106 UR - https://jidc.org/index.php/journal/article/view/34106891 SP - 672-677 AB - <p>Introduction: <em>Streptococcus pneumoniae</em> can be responsible for severe human infections. Optochin resistance has been a potential cause of misidentification of pneumococcus and other members of the mitis group. Hence, rapid and easy optochin resistant (Opt<sup>r</sup>) <em>S. pneumoniae</em> identification is essential.</p><p>Methodology: Atypical pneumococci were characterized using optochin susceptibility, bile solubility based on spectrophotometric reading, serotyping, pulsed field gel electrophoresis (PFGE), 16S rRNA sequencing and PCR-based assays targeting pneumococcal genes <em>lyt</em>A, <em>ply</em>, <em>psp</em>A, <em>cps</em>A, <em>Spn</em>9802 and <em>Spn</em>9828.</p><p>Results: Optical density values for the bile solubility test suggest the identification of four Opt<sup>r</sup> <em>S. pneumoniae</em> and one <em>Streptococcus pseudopneumoniae</em>. All Opt<sup>r</sup> pneumococci harbored <em>cps</em>A, <em>lyt</em>A, <em>ply</em>, Spn9802, <em>Spn</em>9828 and <em>psp</em>A genes. Only <em>ply</em>, <em>spn</em>9802 and <em>Spn</em>9828 genes were detected in <em>S. pseudopneumoniae</em>. The 16S rRNA sequencing differentiates between these two species<em>.</em> Opt<sup>r</sup> <em>S. pneumoniae</em> strains belonged to different genotypes and serotypes (14, 19A, 3 and 9V). Three Opt<sup>r</sup> <em>S. pneumoniae</em> isolates were typed as pspA family 2, while one belonged to pspA family 1. Sequencing of the <em>atp</em>A and <em>atp</em>C gene of the Opt<sup>r</sup> variants revealed three mutations in the ATPase a-subunit (L99I, M23V and V52I) and one mutation in ATPase c-subunit (V48I).</p><p>Conclusions: Our data indicate that bile OD-values provides an accurate, fast and easy method to discriminate between Opt<sup>r</sup> <em>S. pneumoniae </em>and other <em>Streptococcus mitis</em> group. Moreover molecular techniques, confirming the bile test, can be used in order to prevent these atypical pneumococci and alert clinical microbiologists of the presence of these strains in the community.</p> ER -