Epidemiological and clinical features of invasive pneumococcal disease caused by serotype 12F in adults, Japan.

Reiko Shimbashi,Munehisa Fukusumi,Jiro Fujita,Kazunori Oishi,Motoi Suzuki,Hiroaki Takeda,Junichiro Nishi,Kei Kasahara,Yuki Kinjo,Anusak Kerdsin,Tomimasa Sunagawa,Bin Chang,Tetsuya Kubota,Tomoe Shimada,Koji Kuronuma,Tatsuki Ikuse,Takaya Maruyama,Hiroshi Watanabe,Kengo Oshima,Yoshinari Tanabe,Makoto Ohnishi,Takeshi Matsui ,Keiko Tanaka‐Taya

doi:10.1371/journal.pone.0212418

Abstract

Enhanced surveillance of invasive pneumococcal disease (IPD) in adults was conducted during April 2013–March 2018 in 10 of 47 prefectures in Japan, and a total of 1277 IPD patients were enrolled. An emergence of IPD caused by serotype 12F was identified during May 2015–March 2018 through this surveillance. 12F isolates were composed of four related sequence types. In total, 120 patients with 12F IPD were reported during this period. To characterize the clinical features of 12F IPD, the disease characteristics of these patients were compared with those of 1157 patients with non-12F IPD. Compared with the non-12F IPD patients, a significantly lower proportion of 12F IPD patients was aged 65 years or older (55% vs. 70%), vaccinated with 23-valent pneumococcal polysaccharide (4% vs. 14%), had comorbid illness (65% vs. 77%), or were immunocompromised (19% vs. 30%; all P < 0.05). No significant difference in the proportion of case fatalities was found between the two groups. The proportions of those aged 65 years or older (53% vs. 69%) and with bacteremic pneumonia (35% vs. 69%) were significantly lower in 17 patients who died from 12F IPD than in 205 patients who died from non-12F IPD (all P < 0.05). Differences in clinical features were similarly found between 12F IPD patients and patients in low- or intermediate-level invasive potential serogroups. Our data demonstrated that serotype 12F was associated with IPD in younger adults and a lower proportion of comorbid illness, including immunocompromised conditions, in adult IPD, suggesting the high invasive potential of the serotype 12F. In addition, patients who died from 12F IPD were younger and had proportionately more bacteremia without focus. These findings may provide new insight into the pathogenesis of IPD in adults caused by 12F serotype with a high invasive potential.

Highlights

Streptococcus pneumoniae (S. pneumoniae) is harbored in the human nasopharynx, and incidentally invades the bloodstream to cause invasive pneumococcal disease (IPD) [1]
A case of IPD was defined as detection of S. pneumoniae by bacterial culture, and of S. pneumoniae-specific DNA by polymerase chain reaction (PCR) in normally sterile sites such as blood and/or cerebrospinal fluid (CSF); all IPD patients older than 15 years of age were enrolled in this study [17]
1296 IPD cases were enrolled into the study. 1292 of which were diagnosed by positive bacterial culture of sterile samples

Summary

Introduction

Streptococcus pneumoniae (S. pneumoniae) is harbored in the human nasopharynx, and incidentally invades the bloodstream to cause invasive pneumococcal disease (IPD) [1]. Previous studies demonstrated that invasive disease potential of different pneumococcal serotypes, and confirmed that capsular serotype is a major determinant of both the duration of carriage and attack rates in children [3,4,5]. The Japanese government decided to subsidize a 3+1 schedule of heptavalent pneumococcal conjugate vaccine (PCV7) for children less than 5 years of age in November 2010. PCV7 was included in the routine schedule in April 2013, and was replaced with a 13-valent pneumococcal conjugate vaccine (PCV13) in November 2013. A 23-valent pneumococcal polysaccharide vaccine (PPSV23) was licensed in 1988 and included in routine immunization in October 2014 of individuals aged 65 years or older. PCV13 was licensed for adults aged 65 years or older in 2014, and available on a voluntary basis

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