Changes in the Distribution of Capsular Serotypes of <i>Streptococcus pneumoniae</i> Isolated from Adult Respiratory Specimens in Japan

Abstract

Objective The objective of this study was to assess whether the distribution of pneumococcal capsular types has been changed, while also providing basic data on changes in the distribution after the introduction of Pneumococcal conjugated vaccine (PCV)13 in adult medical practice. Methods We analyzed 431 Streptococcus pneumoniae strains (200 in 2006 and 231 in 2012) that had been isolated from respiratory infection specimens from adult patients. Capsular typing was performed by the Quellung reaction and multiplex polymerase chain reaction. Results A comparison of the 2006 and 2012 strains revealed that the number and proportion of strains by serotype increased from 30 (15%) to 46 (20%) for serotype 3, from 4 (2%) to 14 (6%) for serotype 6A, and from 4 (2%) to 13 (6%) for serotype 6C, whereas the number and proportion of strains by serotype decreased from 8 (4%) to 0 (0%) for serotype 4 and from 24 (12%) to 17 (7%) for serotype 6B. From 2006 to 2012, the coverage rate significantly decreased from 39 to 28.1% for PCV7 (p=0.017). Conclusion Our study showed a decrease in the vaccine coverage of PCV7. However, PCV13 covered serotypes 3 and 6A, which are prevalent, as well as penicillin-resistant S. pneumoniae strains. At present, PCV 13 in adult clinical practice seems to be highly significant. However, there is a possibility that the distribution has changed, and careful screening should be continued in the future.

Serotype Replacement in Adult Pneumococcal Pneumonia after the Introduction of Seven-Valent Pneumococcal Conjugate Vaccines for Children in Japan: a Systematic Literature Review and Pooled Data Analysis

“…Using 5 major databases, we comprehensively conducted systematic literature survey to identify studies that reported on the serotype distribution of adult pneumococcal pneumonia. In our pooled data analysis of the 4 studies (1,(17)(18)(19), the proportion of PCV7-covered serotypes decreased significantly and the proportions of serotypes of PCV13-PCV7, PPV23-PCV7, PPV23-PCV13, and non-VTs increased significantly. In summary, the decrease of the proportion of PCV7-covered serotype led to the increase of the proportion of non-PCV7-covered strains.…”

“…Second, there was some heterogeneity between each study in the pooled analysis regarding the diagnostic criteria, differentiation of 6A 6C, and target disease (i.e., including CAP, health care-associated pneumonia, or all LRTI). Particularly, 100 non-pneumonia LRTI cases included in the study by Shoji et al (17) might have influenced our results. We therefore conducted a sensitivity analysis excluding the study by Shoji et al and found that the pooled estimates were almost identical to the primary analysis.…”

“…The study designs could be categorized into case series of pneumococcal LRTI (15,16), prospective surveillance of pneumococcal LRTI or IPD cases (1,(17)(18)(19)(20), and laboratory-based pneumococcal strain surveillance (21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35). One of the prospective surveillance studies of the LRTI referred to the Japanese Respiratory Society (JRS) guidelines for the management of community-acquired pneumonia in adults (36) as diagnostic criteria for LRTI (17). Another 3 prospective surveillance studies of pneumonia also used similar case definitions to the JRS guidelines (1,18,19).…”

“…LRTI, lower respiratory tract infection; CAP, community acquired pneumonia. (17). The study reported the serotype data for 431 LRTI cases including 100 non-pneumonia LRTI cases (n = 50 200 in 2006 and n = 50 231 in 2012), but the pneumonia-specific data were unavailable.…”

Cationic pullulan nanogel as a safe and effective nasal vaccine delivery system for respiratory infectious diseases

“…The current polysaccharide-based multivalent vaccines induce protective immunity against and suppress infections due to S. pneumoniae isolates of the same serotypes as the vaccine antigens and not other serotypes. 18 - 21 In this way, the current multivalent vaccine promotes a vicious cycle of pneumococcal serotype replacement. To overcome this problem, vaccines containing one or more universal antigens that are expressed by all serotypes of S. pneumoniae and thus induce protection against all isolates of S. pneumoniae are desired.…”