A considerably higher proportion of LRTI isolates have STs that are not included in current vaccines, compared with IPD isolates. The proportion of IPD and LRTI isolates with PCV13 STs has declined during the PCV13 era. If PCV15 and/or PCV20 are implemented, a higher proportion of IPD and LRTI cases will be covered however the proportion of LRTI isolates covered will be a minority of all cases.
Pneumococcal resistance to penicillin has generally declined or remained low overall for many years in both IPD and LRTI isolates at all ages in our population, with the exception of serotype 19A, where resistance increased particularly in LRTI isolates and in children (data not shown). Multidrug resistance (MDR) is most common in serotype 19A and in LRTI isolates and is primarily due to resistance to three or more of erythromycin, clindamycin, TMP/SMX, cefuroxime and tetracycline.