The geographic distribution of S. pneumoniae resistance argues that widespread community based monitoring should be implemented as a means of tracking this insidious problem. In most reports the prevalence of resistant isolates is highest among children and the elderly, particularly those in daycare and nursing homes. However, if initial therapy is inadequate because the strain is highly resistant, the outcome is likely to be worse. Resistant strains alter the conformation of the peptidoglycans, and penicillin binds less effectively. Thus, inhibiting cell wall production requires higher penicillin concentration.
Resistant strains display variable gradations of resistance.
Arbitrary levels have been established to assist in antibiotic decision-making, however, there are no clear cut guidelines for antibiotic selection. Currently highly resistant strains remain less common in the U.S.,however, it is anticipated that MICs will continue to drift upward. Multi-drug resistance is being recognized more frequently. Currently in the U.S., erythromycin, tetracycline and TMP-SMZ resistance is frequently present along with penicillin resistance. Rifampin resistance has developed rapidly as well.