Antibiotic-resistant pneumococci--facts and fiction.
The effective treatment of infections caused by penicillin-resistant pneumococci is dependent upon the rapid and accurate laboratory assessment of bacterial susceptibility. The most reliable methods for the susceptibility testing of pneumococci are those of minimum inhibitory concentration (MIC) determination, disk diffusion and the more recently developed E-test. The E-test, in particular, has made pneumococcal testing much easier and allows results to be obtained more rapidly. Current breakpoint recommendations for the susceptibility of pneumococci to penicillin and cephalosporins have been criticised and continue to be the subject of debate. Evidence suggests that strains of pneumococci with an MIC value of 0.06 mg/L for penicillin should be classified as being of intermediate susceptibility. Many of these strains produce zone diameters less than the susceptible breakpoint in oxacillin/methicillin disk procedures. Other proposed changes to NCCLS guidelines are also discussed. Surveys of susceptibility patterns of pneumococci to antibiotics are important in assessing the value of agents in the management of infectious disease. Susceptibility studies have demonstrated that older drugs such as amoxycillin and piperacillin have low MICs against pneumococci, and may therefore be effective in the treatment of infection due to penicillin-intermediate and possibly even penicillin-resistant strains.
Appelbaum
P C
PC
Department of Clinical Pathology, M.S. Hershey Medical Center, Penn State University 17033.
D004352:Drug Resistance, Microbial; D008826:Microbial Sensitivity Tests / Q000379:methods*; D011008:Pneumococcal Infections / Q000188:drug therapy; D013296:Streptococcus pneumoniae / Q000187:drug effects*