Streptococcus pneumoniae isolated from Argentina

ABSTRACT 3 Optochin susceptibility is a key test used for pneumococcal diagnosis, but optochin-4 resistant (Opt R ) pneumococci have been reported in the last two decades. In this work, we 5 characterized 8 clinical optochin-resistant strains, which presented a new mutation, G47V, a 6 predominant A49S (recently reported in Brazil) and A49T. These mutations were found in the c -7 subunit of F 0 F 1 ATPase encoded by the atpC gene, and W206 in the a- subunit encoded by the 8 atpA gene. The clinical Opt R isolates were analyzed by PCR-BOX, MLST, serotype an 9 antimicrobial resistance profiles, and they showed to have no epidemiological relationship. With 10 the purpose to characterize the Opt R mutations that could emerge among clinical strains, we 11 studied a pool of spontaneous Opt R colonies obtained in vitro from the virulent D39 strain. We 12 compared the atpAC mutations of these Opt R pneumococci (with or without the passage by 13 C57B/6 mice) with those described in the clinical isolates. This analysis revealed 3 new mutations, 14 G47V and L26M in the