Epidemiology and Evolution of Invasive Pneumococcal Disease Caused by Multidrug Resistant Serotypes of 19A in the 8 Years After Implementation of Pneumococcal Conjugate Vaccine Immunization in Dallas, Texas

Abstract

In Dallas, PCV7 immunization reduced significantly the incidence of IPD caused by vaccine-type strains. A significant increase in IPD caused by serotype 19A was observed. The penicillin and cefotaxime nonsusceptible STs, not previously identified in Dallas, have recently become an important cause of IPD.

Evolution of Clonal and Susceptibility Profiles of Serotype 19A Streptococcus pneumoniae among Invasive Isolates from Children in Spain, 1990 to 2008

“…Due to this capability, serotype 19A was one of the most prevalent serotypes, together with the group included in the pneumococcal 7-valent conjugate vaccine (PCV7) prior to the introduction of PCV7, among both colonizing strains (17) and invasive isolates (12,22). There has been an increase over time in the prevalence of serotype 19A among invasive and noninvasive Streptococcus pneumoniae isolates, and although the beginning of this increase occurred in some countries prior to PCV7 introduction (6,8,12,15), in others it occurred after (21,28). In addition to the fact that serotype 19A could fill the ecological niche left by the reduction in the number of PCV7 types after vaccine introduction (12,14,25), other facts have been postulated for the multifactorial explanation of the increasing 19A prevalence: (i) the macrolide and penicillin nonsusceptibility prevalence within this serotype that makes it selectable by antibiotic use (12), (ii) the antibiotic pressure together with capsular switching from a resistant clone (5), (iii) the emergence (within serotype 19A) of a minor resistant clone existing prior to introduction of PCV7 (16), (iv) the appearance of new resistant clones (2), or (v) any of them alone or in combination among the streptococcal population in which secular changes in serotype frequencies occur (6,12).…”

In Vitro Activity of Ceftaroline against Clinical Isolates of Streptococcus pneumoniae Recovered in 43 U.S. Medical Centers during 2010-2011

“…However, the positive impact of PCV-7 was transient. Largely as a consequence of capsular switching and as a result of the emergence of pneumococcal serotypes that had existed previously but at low levels, new antimicrobial-resistant serotypes, in particular serotypes 19A and 6C, soon emerged that escaped the effect of the vaccine, and the problem of antimicrobial resistance with S. pneumoniae again began to grow (6,7,8,9,17,21). This cycle has prompted the development of a second, 13-valent pediatric pneumococcal vaccine, PCV-13 (Pfizer), which was introduced into clinical practice in March 2010.…”

Current Trends in Streptococcus pneumoniae Infections and Their Treatment

“…Following PCV7 implementation in resource-rich countries, non-PCV7 serotypes have increased among asymptomatic carriers (''serotype replacement'') [13]. Also, an increase in incidence of IPD due to non-vaccine types (especially serotype 19A) was noted in the US and several other countries in Europe and Asia-Pacific region [12,15,25,45,54]. The absolute rate increase in IPD due to serotype 19A is estimated at *5 cases per 100,000 population compared with decline in the rate of IPD due to PCV7 serotypes [55,56].…”