Nasopharyngeal carriage of Streptococcus pneumoniae in Taiwan before and after the introduction of a conjugate vaccine.

The heptavalent pneumococcal conjugate vaccine was introduced in Taiwan in October 2005. To evaluate the effect of the vaccination, we conducted an active, prospective, large-scale, long-term, and multicenter study to assess the prevalence of nasopharyngeal Streptococcus pneumoniae carriage in Taiwanese children. This study was performed at three tertiary teaching hospitals in northern, central, and southern Taiwan. Questionnaires provided demographic, family/household, and medical history data. Pneumococcal isolates were tested for their susceptibility to various antimicrobial agents and serotypes. In addition, influenza virus and Staphylococcus aureus were recovered from nasopharyngeal and nasal swabs, respectively. Between July 2005 and July 2008, 857 pneumococcal strains were recovered from a total of 6057 children aged >2 months to 5 years (carriage rate, 14.1%). Carriage rates differed geographically and varied with subject age. In a multivariate analysis, having at least one sibling, attendance at day-care centers, a history of otitis media, and history of upper respiratory tract infection in the previous 2 weeks were each associated with a higher risk of pneumococcal colonization of the nasopharynx. Staphylococcus aureus nasal colonization was inversely associated with nasopharyngeal carriage of pneumococcus (p=0.000; odds ratio [OR]: 0.48; 95% CI: 0.39-0.58). Daycare attendance was the only risk factor for carriage of penicillin non-susceptible S. pneumoniae (OR: 2.37; 95% CI: 1.22-4.88). Although vaccination rates rose from 2005 to 2008, no concomitant decrease in S. pneumoniae carriage occurred. The rate of penicillin resistance among S. pneumoniae isolates was 92.8% (using the meningitis criteria). The prevalence of cefotaxime resistance (21.6%) was higher than that of penicillin (6.9%; non-meningitis criteria). Slightly more than half (57.4%) of the isolates belonged to strains covered by the heptavalent pneumococcal conjugate vaccine when both vaccine and vaccine-related serotypes were included. Although vaccination rates rose from 2005 to 2008, no concomitant decrease occurred in S. pneumoniae carriage. Interaction between S. aureus and S. pneumoniae may influence vaccination efficacy. These findings provide baseline data to further compare pneumococcal carriage rates and antibiotic resistance patterns in Taiwanese children as vaccination rates continue to increase.

Kuo CY ，Hwang KP ，Hsieh YC ，Cheng CH ，Huang FL ，Shen YH ，Huang YC ，Chiu CH ，Chen PY ，Lin TY ... -  《-》

Declining serotype coverage of new pneumococcal conjugate vaccines relating to the carriage of Streptococcus pneumoniae in young children.

Asymptomatic carriage of the opportunistic pathogen Streptococcus pneumoniae is known to precede the development of invasive disease. Young children are one of the major reservoirs for pneumococci and worldwide over 700,000 children under two years old die due to invasive pneumococcal disease each year. Heptavalent conjugate vaccine (PCV-7) was introduced into the UK childhood immunisation schedule in September 2006. Our objective was to assess the emergence of colonising serotypes in young children in the three years following PCV-7 implementation. Time-series prevalence survey set in the paediatric outpatients department of a large UK teaching hospital. Participants were children aged four years and under attending the outpatients department during PCV-7 introduction (October 2006-February 2007) and in the same months of the two subsequent years. The main outcome measure was prevalence of pneumococcal carriage by serotype. The rate of pneumococcal nasopharyngeal carriage remained stable during the three year period. We observed a significant 69% (95% CI, -40% to -118%, p<0.0001) decrease in carriage of PCV-7 serotypes during PCV-7 implementation and a concomitant increase in the proportion of non PCV-7 serotypes. The most prevalent emerging non-vaccine serotypes were 6C, 11A, 19A and 22F. By March 2009, PCV-13 was predicted to cover only 33.3% (95% CI, 24.2-42.5%) of strains carried in the study population. Although the overall pneumococcal carriage rate remained stable between 2006 and 2009, we observed a significant decrease in the serotype coverage of PCV-7 and PCV-13. PCV-7 was highly successful in reducing carriage of vaccine serotypes. However, the increase in the proportion of non-vaccine serotypes found both in our study and causing invasive disease currently in the UK, underlines the importance of continued surveillance of carriage and disease.

Tocheva AS ，Jefferies JM ，Rubery H ，Bennett J ，Afimeke G ，Garland J ，Christodoulides M ，Faust SN ，Clarke SC ... -  《-》

Effect of a nonavalent conjugate vaccine on carriage of antibiotic-resistant Streptococcus pneumoniae in day-care centers.

Dagan R ，Givon-Lavi N ，Zamir O ，Fraser D ... -  《PEDIATRIC INFECTIOUS DISEASE JOURNAL》

Nasopharyngeal carriage of Streptococcus pneumoniae in Gambian children who participated in a 9-valent pneumococcal conjugate vaccine trial and in their younger siblings.

Cheung YB ，Zaman SM ，Nsekpong ED ，Van Beneden CA ，Adegbola RA ，Greenwood B ，Cutts FT ... -  《-》

[Study of nasopharyngeal colonization by Streptococcus pneumoniae and its antibiotics resistance in healthy children less than 2 years of age in the Marrakech region (Morocco)].

The healthy carrier of Streptococcus pneumoniae (S. pneumoniae) has been studied very little at the national level. With the emergence of antibiotic-resistant strains worldwide, and the emergence of new serotypes, an epidemiological survey is needed before the vaccine can be introduced in Morocco. This study's objective was to determine the prevalence and risk factors of pneumococcal nasopharyngeal carriage in children less than 2 years of age in the Marrakech region and to assess the antibiotic susceptibility of the isolates and the serotypes present prior to the introduction of the conjugate pneumococcal vaccine. From 2008 to 2009, 660 nasopharyngeal samples were collected on children under 2 years of age during scheduled visits to dispensaries for routine immunization in the Marrakech region. S. pneumoniae carriage was found in 45.8% of children. Of the 660 samples, 302 strains were isolated. The percentage of pneumococcal strains with reduced susceptibility to penicillin (PRSP) was 34.7%. Among these strains, 87.1% showed low-level resistance and 12.9% high-level resistance. Resistance to amoxicillin was found in 3.3% of the strains and no strains were resistant to cefotaxime. Several risk factors for pneumococcal carriage were identified, the main ones being breastfeeding less than 2 months, the presence of more than one sibling, passive smoking, and low socioeconomic level. The most frequent serotypes were 19F, 6, 14, 23, 18, and 9. The study of the vaccine serotype distribution showed that the theoretical vaccine coverage of the 7 valent vaccines was at 57% for all the isolates. These data show the frequency and the risk factors on nasopharyngeal carriage, and report the status of penicillin resistance of strains carrying children less than 2 years of age in the Marrakech region. The fluctuation of circulating serotypes at the national level underscores the importance of epidemiological surveillance carried out before the introduction of the heptavalent vaccine in Morocco.

Bouskraoui M ，Soraa N ，Zahlane K ，Arsalane L ，Doit C ，Mariani P ，Bingen E ... -  《-》