Dynamics of Streptococcus pneumoniae nasopharyngeal carriage with high heptavalent pneumococcal conjugate vaccine coverage in Central Greece.

In order to study whether the use of the heptavalent pneumococcal conjugate vaccine (PCV7) led to a shift in the Streptococcus pneumoniae serotypes distribution and whether it modified the resistance to antibiotics, 2649 nasopharyngeal samples were obtained between 2005 and 2009, from children attending day-care centers in Central Greece. The percentage of attendees vaccinated with ≥1 dose of PCV7 increased from 12.9% (2005) to 95.5% (2009). Non-PCV7 serotypes replaced those belonging to PCV7. In 2009, 19F was virtually the only PCV7 serotype that continued to circulate. A significant increase in the frequency of penicillin-intermediate (oral penicillin V breakpoints) isolates coincided with a marked reduction in isolates with high resistance to penicillin. Several non-PCV7 serotypes colonized the children, but their frequency varied substantially from year to year. Each one of 14 specific non-PCV7 serotypes, i.e. 6A, 11A, 15B, 23A, 10A, 16F, 38, 22F, 15C, 19A, 35F, 24F, 6C, and 7F, accounted for ≥2% of pneumococcal isolates in at least 2 annual surveillances. An increase in non-PCV7 serotypes with antibiotic resistance, beyond 6A and 19A, occurred. Intermediate resistance to penicillin was observed in serotype 23B, 15B, 15C, 15A, 35F, 6C, and 24F pneumococci. Their exact role in invasive and non-invasive disease remains to be seen in the years ahead.

Grivea IN ，Tsantouli AG ，Michoula AN ，Syrogiannopoulos GA ... -  《-》

Dynamics of pneumococcal carriage among day-care center attendees during the transition from the 7-valent to the higher-valent pneumococcal conjugate vaccines in Greece.

In Greece recently, higher-valent pneumococcal conjugate vaccines (PCVs) replaced the 7-valent (PCV7); the 10-valent (PCV10) became available in May 2009 and the 13-valent (PCV13) in June 2010. We investigated the nasopharyngeal colonization with Streptococcus pneumoniae in day-care center attendees in Athens and the prefecture of Viotia. Between December 2010 and June 2011, nasopharyngeal cultures were obtained 4 times, at enrollment and then every 6 to 8 weeks. Among the 233 children, 225 (96.6%) had been vaccinated with ≥1 dose of PCV7. One tenth of the PCV7 vaccinated attendees had also received ≥1 dose of PCV13 or PCV10. During the 4 samplings, 358 isolates were recovered from a total of 874 samples. Of the 233 children, 183 (78.5%) were found to carry S. pneumoniae at least once. The overall serotype distribution among carriers was similar regardless of the time lapsed since the last PCV7 dose. A high frequency of 19A (17.1%) coincided with a low frequency of 19F (1.4%). Non-PCV13 serotypes accounted for 73.1% of the isolates; 23B, 15B/C, 16F, 21, 11A, 15A, 6C, 10A, 22F and 23A were the most common. Among attendees aged 24-59 months (median age 42 months), prolonged carriage of a non-PCV13 serotype was relatively common, mainly for 21 and 16F. One out of 4 cases of colonization with the prevalent non-PCV13 serotypes was followed by persistent carriage for 5 to 14 weeks. During this period of transition to the higher-valent PCVs in the day-care center setting, non-PCV13 serotypes dominated and exhibited prolonged colonization. The frequency and the duration of prolonged carriage tends to be increased, if sampling frequency increases and the carriage time before and after positive cultures is taken into consideration. Further studies regarding the fitness of the colonizing non-PCV13 serotypes will likely to be seen in the future.

Grivea IN ，Priftis KN ，Giotas A ，Kotzia D ，Tsantouli AG ，Douros K ，Michoula AN ，Syrogiannopoulos GA ... -  《-》

Changes in nasopharyngeal carriage and serotype distribution of antibiotic-resistant Streptococcus pneumoniae before and after the introduction of 7-valent pneumococcal conjugate vaccine in Hong Kong.

This study assessed the changes in serotype distribution and antibiotic resistance of Streptococcus pneumoniae isolates in children before and after introduction of the 7-valent pneumococcal conjugate vaccine (PCV7) in Hong Kong. Nasopharyngeal specimens were collected from 1978 and 2211 children (ages, 2 to 6 years) attending day care centers or kindergartens in period 1 (1999-2000) and period 2 (2009-2010), respectively. Carriage of PCV7 serotypes decreased from 12.8% to 8.6% (P < 0.01). The relative contribution of PCV7 serotypes 14 and 18C had decreased, whereas that for non-PCV7 serotypes 19A, 6A, 6C, 23A, and 15B had increased. In period 2, PCV7 penetration rate (at least 1 dose) for children aged 2, 3, 4, and 5 years was 43%, 35.7%, 26.7%, and 20.4%, respectively. In multivariate analysis, PCV7 use was the only independent variable associated with fewer PCV7 serotype carriages (odds ratio 0.5; P = 0.001). In period 2, high rates of dual penicillin/erythromycin nonsusceptibility were found in serotypes 6B (77.3%), 14 (100%), 19F (100%), 23F (78%), 19A (75%), 6A (87.8%), 6C (59.3%), and 23A (78.9%).

Ho PL ，Chiu SS ，Chan MY ，Ang I ，Chow KH ，Lau YL ... -  《-》

Impact of heptavalent pneumococcal conjugate vaccine on nasopharyngeal carriage of penicillin-resistant Streptococcus pneumoniae among day-care center attendees in central Greece.

Grivea IN ，Panagiotou M ，Tsantouli AG ，Syrogiannopoulos GA ... -  《PEDIATRIC INFECTIOUS DISEASE JOURNAL》

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

Dagan R 《-》