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Category: Bacterial Pathogenesis
Streptococcus pneumoniae, Page 1 of 2
< Previous page | Next page > /docserver/preview/fulltext/10.1128/9781555817572/9781555813291_Chap23-1.gif /docserver/preview/fulltext/10.1128/9781555817572/9781555813291_Chap23-2.gifAbstract:
Streptococcus pneumoniae is the bacterial pathogen most frequently implicated in community-acquired respiratory tract infections (RTI) and also has the distinction of being the leading cause of invasive bacterial disease in the very young and the elderly. Aminoglycoside resistance in pneumococci is not usually reported in surveillance studies, largely because antibiotics from this class are rarely used to treat pneumococcal infections. Macrolides, lincosamides, and streptogramins, though chemically distinct, are usually considered together because they inhibit protein synthesis by binding to overlapping sites in the 50S bacterial ribosomal subunit. β-lactam antibiotics target one or more of the penicillin-binding proteins (PBPs) involved in a late step in peptidoglycan biosynthesis. Fluoroquinolones interact with eubacterial type 2 topoisomerases, DNA gyrase, and topoisomerase IV. Both of these enzymes are essential for DNA replication, and both function as tetrameric heterodimers (A2B2). DNA gyrase and topoisomerase IV are encoded by sets of homologous genes, gyrA and gyrB and parC and parE, respectively. Trimethoprim (TMP) is a diaminopyrimidine that selectively inhibits bacterial dihydrofolate reductase. Chloramphenicol is a small molecule that has been described as a structural analog of puromycin, an aminoacylated nucleoside. S. pneumoniae is an important community and hospital pathogen that is becoming increasingly multidrug resistant. For community-acquired respiratory tract infections, therapy is generally empiric and drugs are needed to cover the common clones that are becoming more difficult to treat. In invasive situations and even in very highly penicillin-resistant pneumococci, the use of conjugate vaccines has significantly lessened incidence in children.
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