Impact of antibiotic resistance on chemotherapy for pneumococcal infections

Over the past three decades, penicillin-resistant pneumococci have emerged worldwide. In addition, penicillin-resistant strains have also decreased su sceptibility to other beta-lactams (including cephalosporins) and these str ains are often resistant to other antibiotic groups, making the treatment o ptions much more difficult. Nevertheless, the present in vitro definitions of resistance to penicillin and cephalosporins in pneumococci could not be appropriated for all types of pneumococcal infections. Thus, current levels of resistance to penicillin and cephalosporin seem to have little, if any, clinical relevance in nonmeningeal infections (e.g., pneumonia or bacterem ia). On the contrary, numerous clinical failures have been reported in pati ents with pneumococcal meningitis caused by strains with MICs greater than or equal to 0.12 mu g/ml, and penicillin should never be used in pneumococc al meningitis except when the strain is known to be fully susceptible to th is drug. Today, therapy for pneumococcal meningitis should mainly be select ed on the basis of susceptibility to cephalosporins, and most patients may currently be treated with high-dose cefotaxime (+/-) vancomycin, depending on the levels of resistance in the patient's geographic area. In this revie w, we present a practical approach, based on current levels of antibiotic r esistance, for treating the most prevalent pneumococcal infections. However , it should be emphasized that the most appropriate antibiotic therapy for infections caused by resistant pneumococci remains controversial, and compa rative, randomized studies are urgently needed to clarify the best antibiot ic therapy for these infections.