Increasing Prevalence of Multidrug-Resistant Streptococcus Pneumoniae in the United States

INCREASING PREVALENCE OF MULTIDRUG-RESISTANTSTREPTOCOCCUS PNEUMONIAEIN THE UNITED STATES Whitney CG, et al. N Engl J Med 2000;343:1917: The authors report the results of the CDC-sponsored “Active Bacterial Core Surveillance” program of pneumococcal infections in regions that account for 16.5 million persons or about 6% of the U.S. population. The analysis was restricted to invasive pneumococcal disease defined by the isolation of S. pneumoniae from a normally sterile site. Results for 3475 isolates reported in 1998 showed 14% were resistant to penicillin (MIC ≥2 μg/mL) and 10% showed intermediate resistance (MIC 0.1 μg/mL–1.0 μg/mL), as shown in table 5. It can also be seen that strains resistant to penicillin were often resistant to other antibiotics as well:TABLE 5Comment. The results of this study are quite similar to those previously reported by SENTURY, TRUST, and the Alexander Project. The authors concluded that “24% of isolates from 1998 were resistant to penicillin,” but this is misleading because their definition of resistance includes intermediate resistance, which is relevant only for pyogenic meningitis. For most infections, such as pneumococcal pneumonia or sinusitis, the true rate of clinically relevant resistance was 14%, which is high, but not as ominous as implied by the authors. With regard to geography, Tennessee and Georgia had the highest rates of resistance whereas California and New York State had the lowest. High rates were also disproportionately represented in children <5 years of age. There was no significant difference in penicillin resistance for those with pyogenic meningitis and no difference between those who survived or did not survive this infection. The authors noted that the percentage of strains to penicillin increased from 21% in 1995 to 25% in 1998. Serotyping showed that 88% of all isolates are included in Pneumovax® and 78% are included in the new protein-conjugated vaccine.