ABSTRACT
Nasopharyngeal colonization by Streptococcus pneumoniae is an important initial step for the subsequent development of pneumococcal infections. Pneumococci have many virulence factors that play a role in colonization. Pneumolysin (PLY), a pivotal pneumococcal virulence factor for invasive disease, causes severe tissue damage and inflammation with disruption of epithelial tight junctions. In this study, we evaluated the role of PLY in nasal colonization of S. pneumoniae using a mouse colonization model. A reduction of numbers of PLY-deficient pneumococci recovered from nasal tissue, as well as nasal wash, was observed at days 1 and 2 post-intranasal challenges, but not later. The findings strongly support an important role for PLY in the initial establishment nasal colonization. PLY-dependent invasion of local nasal mucosa may be required to establish nasal colonization with S. pneumoniae. The data help provide a rationale to explain why an organism that exists as an asymptomatic colonizer has evolved virulence factors that enable it to occasionally invade and kill its hosts. Thus, the same pneumococcal virulence factor, PLY that can contribute to killing the host, may also play a role early in the establishment of nasopharynx carriage.
Subject(s)
Carrier State/microbiology , Pneumococcal Infections/microbiology , Streptococcus pneumoniae/growth & development , Streptococcus pneumoniae/metabolism , Streptolysins/metabolism , Animals , Bacterial Proteins/metabolism , Female , Mice, Inbred CBA , Streptolysins/deficiency , Virulence Factors/deficiency , Virulence Factors/metabolismABSTRACT
A case of an 82-year-old female with primary laryngeal cryptococcosis who had undergone long-term corticosteroid therapy for chronic obstructive pulmonary disease and rheumatoid arthritis is reported. She complained hoarseness with swallowing pain and irritability of the larynx for over a month. Endoscopic examination revealed a white, exudative irregular region on right arytenoid that mimicked a laryngeal carcinoma. Histological examination showed pseudoepitheliomatous hyperplasia and severe submucosal inflammation with ovoid budding yeasts by Grocott's stain. A serological study indicated a high titer of cryptococcal antigen. After treating with oral fluconazole for 3 months, her primary lesion of larynx turned to be clear. We implicate a long-term use of steroids as the significant risk factor in developing cryptococcosis of the larynx.
