Changes in Streptococcus pneumoniae serotype distribution in invasive disease and nasopharyngeal carriage after the heptavalent pneumococcal conjugate vaccine introduction in Bogotá, Colombia.

In Bogotá, the Heptavalent Conjugate Vaccine (PCV7) was introduced into childhood immunization schedule since 2009. The aim of this study was to assess the changes in serotype distribution and penicillin susceptibility of Streptococcus pneumoniae isolates recovered from nasopharyngeal samples and invasive disease among children living in Bogotá, before and after PCV7 introduction. Nasopharyngeal swabs were collected from healthy children aged between 12 and 18 months of age before (years 2005-2006) and after (2011) PCV7 introduction. Identification of S. pneumoniae was performed by multiplex PCR. Serotype was determined by PCR and Quellung reaction. Susceptibility to penicillin, ceftriaxone, trimethoprim-sulfamethoxazole, chloramphenicol, tetracycline and erythromycin was evaluated. In addition, distribution of serotypes and antimicrobial susceptibility before and after vaccine introduction among invasive isolates recovered from children ≤2 years old living in Bogotá was analyzed. Prevalence of pneumococcal nasopharyngeal carriage declined from 55.7% (137/246) in unvaccinated to 44.2% (87/197) (p=0.01) in vaccinated children. The proportion of children carrying PCV7 serotypes decreased from 23.6% (58/246) to 7.6% (15/197) (p<0.001). The decrease was counterbalanced by an increase in the proportion of non-PCV7 serotypes. The most prevalent among emerging serotypes were 15A, 15B, 15C, 11A and 35B. Among IPD isolates, PCV7 serotypes decreased from 69.1% (235/340) in 2005/2009 to 38.0% (32/84) in 2010/2011 (p<0.001). The increase of non-PCV7 serotypes was significant. Resistance to penicillin among invasive isolates recovered from meningitis decreased from 41.1% (30/73) in the pre-vaccine period to 14.2% (2/14) in post-vaccine period (p=0.02). A decrease in the prevalence of pneumococcal nasopharyngeal carriage following the introduction of PCV7 vaccine, have been overshadowed by an important surge in the prevalence of non-PCV7 serotypes. Systematic surveillance combining nasopharyngeal carriage surveys and IPD detection could help in evaluating the impact of conjugate vaccines.

Parra EL ，De La Hoz F ，Díaz PL ，Sanabria O ，Realpe ME ，Moreno J ... -  《-》

Serotype distribution and antimicrobial susceptibilities of nasopharyngeal isolates of Streptococcus pneumoniae from healthy children in the 13-valent pneumococcal conjugate vaccine era.

Few epidemiological data are available since the introduction of 13-valent pneumococcal vaccine (PCV13) in 2010. We conducted a cross-sectional study to estimate the prevalence of Streptococcus pneumoniae (SP) nasopharyngeal carriage in healthy Italian infants and young children and to evaluate the impact of PCV13 on pneumococcal colonization. In the trimester September-December 2011 nasopharyngeal swabs were collected from healthy children aged 3-59 months presenting for routine well careat 16 primary care pediatricians in Milan. SP carriage isolates were serotyped and tested for antimicrobial resistance using EUCAST breakpoints. Among 1250 enrolled children, 618 had received at least 1 dose of PCV13, 292 at least 1 dose of PCV7, 94 a combination of the two vaccines and 246 were not vaccinated. The prevalence of SP carriage was 27% (95% confidence interval [CI] 25-30). At multivariable analysis, age≥25 months (prevalence ratio [PR]=0.74) and use of antibiotics in the previous 3 months (PR=0.67) were associated with lower SP carriage prevalence. Having siblings (PR=1.79 for 1 sibling and PR=2.23 for ≥2 siblings), day-care attendance (PR=2.27) and respiratory tract infections in the previous 3 months (PR=1.39) were associated with higher SP carriage prevalence. The immunization status for SP was not associated with SP carriage at univariable or at multivariable analysis. The most common carriage isolates were 6C, 19A and 23A. The prevalence of the six additional PCV13 serotypes carriage in children appropriately vaccinated with PCV13 was lower than in children appropriately vaccinated with PCV7 (0 vs. 0.060); the greater reduction in prevalence of carriage was observed for serotype 19A (0 vs. 0.041). Serotype 6C was the most common drug-resistant serotype (17.2%). Further epidemiological studies are needed to assess changes in circulating SP serotypes following the large-scale introduction of PCV13.

Zuccotti G ，Mameli C ，Daprai L ，Garlaschi ML ，Dilillo D ，Bedogni G ，Faccini M ，Gramegna M ，Torresani E ，PneuMi Study Group (PMSG) ，Ballerini E ，Benincaso A ，Bonvissuto M ，Bricalli D ，Brioschi M ，Calloni CS ，Camiletti MI ，Colella G ，De Angelis L ，Decarlis S ，Di Nello F ，Dozzi M ，Galli E ，Gandini V ，Giuliani MG ，Laviola F ，Loda B ，Macedoni M ，Mazzucchi E ，Metta MG ，Moscatiello A ，Nannini P ，Petruzzi M ，Picicco D ，Picciotti M ，Pisanelli S ，Porta N ，Ramponi G ，Redaelli F ，Rubini R ，Sala N ，Saitta V ，Scelza G ，Tiso RM ，Tomasetto M ，Torcoletti M ，Travaini M ，Valentini M ，Vessia C ... -  《-》

Pneumococcal carriage and invasive disease in children before introduction of the 13-valent conjugate vaccine: comparison with the era before 7-valent conjugate vaccine.

Sharma D ，Baughman W ，Holst A ，Thomas S ，Jackson D ，da Gloria Carvalho M ，Beall B ，Satola S ，Jerris R ，Jain S ，Farley MM ，Nuorti JP ... -  《-》

Decline in Pneumococcal Nasopharyngeal Carriage of Vaccine Serotypes After the Introduction of the 13-Valent Pneumococcal Conjugate Vaccine in Children in Atlanta, Georgia.

Desai AP ，Sharma D ，Crispell EK ，Baughman W ，Thomas S ，Tunali A ，Sherwood L ，Zmitrovich A ，Jerris R ，Satola SW ，Beall B ，Moore MR ，Jain S ，Farley MM ... -  《-》

Impact of pneumococcal conjugate vaccine on infections caused by antibiotic-resistant Streptococcus pneumoniae.

Dagan R 《-》