serotypes that frequently colonise the human nasopharynx are common recipients of penicillin-binding protein gene fragments from .

is an important global pathogen that causes bacterial pneumonia, sepsis and meningitis. Beta-lactam antibiotics are the first-line treatment for pneumococcal disease, however, their effectiveness is hampered by beta-lactam resistance facilitated by horizontal genetic transfer (HGT) with closely related species. Although interspecies HGT is known to occur among the species of the genus , the rates and effects of HGT between and its close relatives involving the penicillin binding protein () genes remain poorly understood. Here we applied the fastGEAR tool to investigate interspecies HGT in genes using a global collection of whole-genome sequences of , and . With these data, we established that pneumococcal serotypes 6A, 13, 14, 16F, 19A, 19F, 23F and 35B were the highest-ranking serotypes with acquired fragments. was a more frequent pneumococcal donor of fragments and a source of higher nucleotide diversity when compared with . Pneumococci that acquired fragments were associated with a higher minimum inhibitory concentration (MIC) for penicillin compared with pneumococci without acquired fragments. Together these data indicate that contributes to reduced β-lactam susceptibility among commonly carried pneumococcal serotypes that are associated with long carriage duration and high recombination frequencies. As pneumococcal vaccine programmes mature, placing increasing pressure on the pneumococcal population structure, it will be important to monitor the influence of antimicrobial resistance HGT from commensal streptococci such as .