Streptococcus pneumoniae as an agent of nosocomial infection: treatment in the era of penicillin-resistant strains

Abstract. Streptococcus pneumoniae is a well-known agent of community-acquired infections such as sinusitis, otitis media, pneumonia, bacterial meningitis, bacteremia, and acute exacerbations of chronic bronchitis. However, the role of S.pneumoniae as a cause of nosocomial infections of respiratory tract, bloodstream, and central nervous system is more and more recognised, primarily in high-risk patients with depression of their immune function. Therapy of pneumococcal infections is made difficult by the emergence and spread of bacterial resistance to penicillin and other beta-lactams as well as to a number of antimicrobials such as macrolides, chloramphenicol, tetracyclines, and sulphonamides. This epidemiological situation is worrisome worldwide, but it primarily affects some European countries, North America, South Africa, and Far East. The main consequence on the therapeutic ground is that in severe infections such as bacterial meningitis, the addition of vancomycin to a third-generation cephalosporin is advisable while awaiting laboratory test results, even in areas with low prevalence of penicillin-resistant pneumococci. However, a beta-lactam agent can be a valid choice also in the presence of potentially lethal infections such as pneumonia or in the case of penicillin intermediately resistant isolates. In recent years, new alternative molecules have been introduced into clinical practice for therapy of infections caused by penicillin-resistant pneumococci. In both in-vivo and in-vitro studies, drugs of the classes of fluoroquinolones (levofloxacin, moxifloxacin, gatifloxacin), streptogramins (quinupristin/dalfopristin), and oxazolidinones (linezolid) have shown good microbiologic and clinical efficacy against penicillin-resistant pneumococci. In this era of worldwide spread of penicillin-resistant pneumococci, use of polysaccaride or conjugated vaccines is highly recommended.