Summary

Multi-drug resistance to antibiotics continues to increase as strains not covered by the pneumococcal conjugate vaccine PCV7 have replaced those included in the vaccine as the source of disease in the US population. Although these non-vaccine strains represented only 16% of the multiple resistant isolates before the introduction of the vaccine in 2000, they represent one of every two multiple resistant isolates today. Resistance is expected to increase until it reaches a plateau, dependent upon the cumulative exposure to antibiotics in the United States population.