Penicillin-resistant Pneumococcus Isolation

Twenty-six penicillin non-susceptible Streptococcus pneumoniae were isolated by culturing nasopharyngeal swabs obtained from healthy HIV infected adults in Tanzania as part of the randomized clinical trial CoTrimResist (ClinicalTrials.gov identifier: NCT03087890, registered on 23rd March, 2017). The study population and bacterial isolates have been described previously [18 (link)]. Streptococcus pneumoniae was identified by conventional methods including optochin disk and bile susceptibility and further confirmation was done by Matrix-Assisted Laser Desorption/Ionization-Time of Flight (MALDI-TOF) mass spectrometry (MS), using the Microflex LT instrument and MALDI Biotyper 3.1 software (Bruker Daltonics, Bremen, Germany). Isolates with discordant results between MALDI-TOF and conventional identification with optochin disk and bile susceptibility were omitted.
Serotyping of Streptococcus pneumoniae was performed by latex agglutination (Immulex™ Pneumotest Kit; SSI Diagnostica A/S, Hillerød, Denmark).