Novel mutations in a patient isolate of Streptococcus agalactiae with reduced penicillin susceptibility emerging after long-term oral suppressive therapy.

Penicillin nonsusceptibility has been demonstrated in group B streptococci (GBS), but there is limited information regarding mechanisms of resistance. We report a case of GBS with reduced susceptibility to penicillin emerging after long-term suppressive oral penicillin therapy for a prosthetic joint infection. Molecular characterization of the isolate before and after long-term penicillin therapy revealed 5 mutations in the ligand-binding regions of PBP1a, -2a, and -2x not previously reported in GBS.

High-Grade Neuroendocrine Carcinoma Within a Tracheal Polyp: A Case Report.

INTRODUCTION: Primary carcinomas of the trachea are rare, with a reported annual incidence of one in a million. We present a case of a previously undescribed polypoid high-grade neuroendocrine carcinoma of the trachea. Resection of the carcinoma revealed only superficial invasion of the mucosa and without evidence of local or distant metastatic disease. Histologically, the tumor had high-grade features with necrosis and a high mitotic index. METHODS: Characterization of this rare neuroendocrine carcinoma of the trachea was performed by immunohistochemistry and whole-genome sequencing. RESULTS: Immunohistochemistry result was positive for neuroendocrine markers, p16 and an elevated Ki-67. Whole-genome sequencing of the lesion was performed and revealed a very unusual and very distinct mutational signature without relationship to other relevant neuroendocrine carcinomas. Neither known driver nor targetable mutations were found by whole-genome sequencing. Analysis of the sequence of numerous viral elements of human papillomavirus-18 suggests that the pathogenesis of the lesion is related to viral integration. The patient developed distal recurrence, which progressed to widespread pulmonary dissemination, presumably through aerogenous spread of disease. CONCLUSIONS: This is the first characterization of this type of tracheal tumor, including genomic findings, pathogenesis, and natural history.

Comparative Genomic Analyses of Streptococcus pseudopneumoniae Provide Insight into Virulence and Commensalism Dynamics.

Streptococcus pseudopneumoniae (SPPN) is a recently described species of the viridans group streptococci (VGS). Although the pathogenic potential of S. pseudopneumoniae remains uncertain, it is most commonly isolated from patients with underlying medical conditions, such as chronic obstructive pulmonary disease. S. pseudopneumoniae can be distinguished from the closely related species, S. pneumoniae and S. mitis, by phenotypic characteristics, including optochin resistance in the presence of 5% CO2, bile insolubility, and the lack of the pneumococcal capsule. Previously, we reported the draft genome sequence of S. pseudopneumoniae IS7493, a clinical isolate obtained from an immunocompromised patient with documented pneumonia. Here, we use comparative genomics approaches to identify similarities and key differences between S. pseudopneumoniae IS7493, S. pneumoniae and S. mitis. The genome structure of S. pseudopneumoniae IS7493 is most closely related to that of S. pneumoniae R6, but several recombination events are evident. Analysis of gene content reveals numerous unique features that distinguish S. pseudopneumoniae from other streptococci. The presence of loci for competence, iron transport, pneumolysin production and antimicrobial resistance reinforce the phylogenetic position of S. pseudopneumoniae as an intermediate species between S. pneumoniae and S. mitis. Additionally, the presence of several virulence factors and antibiotic resistance mechanisms suggest the potential of this commensal species to become pathogenic or to contribute to increasing antibiotic resistance levels seen among the VGS.