竹内 典子

After introducing the 13-valent pneumococcal conjugate vaccine (PCV13) for children, a change in the prevalence of different Streptococcus pneumoniae serotypes that cause invasive pneumococcal diseases (IPDs) has been observed. The prevalence of vaccine serotypes has decreased and that of non-vaccine serotypes has increased. Currently, serogroup 24 has become one of the major non-vaccine serotypes causing IPDs in children in Japan. The aim of this study was to characterize clinical and genomic features of S. pneumoniae serogroup 24 strains isolated from sterile body sites in Japanese children. Serotyping, multi-locus sequence typing and genomic analysis of capsular polysaccharides of 61 strains of serogroup 24 were performed from 2015 to 2021. Among the 61 strains, 36, 23 and two belonged to serotypes 24F, 24B and 24C, respectively. The 24F sequence type (ST) 2572 and 24B ST 2572 were the major serotypes and sequence types observed from 2015 to 2019. By contrast, 24F ST 162 and 24B ST 2754 were the two major serotypes and sequence types observed after 2020. Two strains of serotype 24C were detected for the first time in Japan. Sequence analysis of the abpA gene, which plays a role in the synthesis of capsular polysaccharides in S. pneumoniae , was performed to distinguish different strains of serogroup 24. After the introduction of PCV13 in Japan, serogroup 24 has become one of the most prevalent non-vaccine serotypes causing IPDs in children. This serogroup has not been targeted in the next-generation pneumococcal conjugate vaccines. Therefore, monitoring of S. pneumoniae serogroup 24 that causes IPDs in children is essential.

This is the first report on a population-based prospective study of invasive group B streptococcus (GBS) disease among children aged <15 years conducted over a period of 11 years in Japan. This study investigated the incidence and clinical manifestations of invasive GBS disease in children in Chiba Prefecture, Japan, and analysed the serotypes and drug susceptibility of GBS strains isolated during the study period. Overall, 127 episodes of invasive GBS disease were reported in 123 patients. Of these, 124 were observed in 120 patients aged <1 year, and the remaining three episodes were reported in a 9-year-old child and two 14-year-old children with underlying disease. For patients aged <1 year, the incidence rate per 1000 live births was 0.24 (0.15-0.36). The incidences of early-onset disease and late-onset disease were 0.04 (0.0-0.09) and 0.17 (0.08-0.25), respectively. The rate of meningitis was 45.2%, and the incidence of GBS meningitis was higher than that of other invasive diseases among children in Japan. Of the 109 patients for whom prognosis was available, 7 (6.4%) died and 21 (19.3%) had sequelae. In total, 68 strains were analysed. The most common were serotype III strains (n = 42, 61.8%), especially serotype III/ST17 strains (n = 22, 32.4%). This study showed that the incidence of invasive GBS disease among Japanese children was constant during the study period. Because of the high incidence of meningitis and disease burden, new preventive strategies, such as GBS vaccine, are essential.

Streptococcus pneumoniae is one of the leading causes of meningitis in children. In Japan, since the introduction of the 13-valent pneumococcal conjugate vaccine (PCV13), the number of pneumococcal meningitis due to non-PCV13 serotypes in children has increased. To clarify the clinical outcomes, serotype distributions, and antimicrobial susceptibility of isolated S. pneumoniae strains from pediatric pneumococcal meningitis, we clinically and bacteriologically analyzed 34 cases of pediatric pneumococcal meningitis that were reported after the PCV13 introduction era in Japan. The median age at diagnosis was 1 year (range: 3 months-13 years). Ten (29.4%) patients had underlying diseases. Twenty-nine (85.3%) patients had received at least one dose of any pneumococcal vaccine. Of the 34 patients with pneumococcal meningitis, 6 had sequelae, and 4 died. Nine (26.5%) strains were resistant to penicillin; five (15%) strains to meropenem, with an MIC of 0.5 μg/mL. All strains were susceptible to vancomycin and linezolid. Daptomycin's MIC50 was 0.064 μg/mL and MIC90 was 0.094 μg/mL. Among the tested strains, only four were PCV13 serotypes. Penicillin-resistant S. pneumoniae was isolated from 30.0% of the patients with sequelae and death. Particularly, the proportion of serotype 10A in the sequelae and deceased cases was significantly higher than that in the complete recovery cases. We should carefully monitor the serotype and drug susceptibility of S. pneumoniae strains isolated from patients with meningitis after the PCV13 era and reconsider the treatment strategy to prepare against further drug-resistant pneumococcal strains. IMPORTANCE We analyzed 34 cases of pediatric pneumococcal meningitis that were reported after the 13-valent pneumococcal conjugate vaccine (PCV13) introduction era in Japan. Our study revealed that pneumococcal meningitis in children was mainly caused by non-PCV13 serotypes; all cases with sequelae and death were caused by non-PCV13 serotypes. Moreover, all serotypes of penicillin resistant Streptococcus pneumoniae strains (26.5%; 9/34) were non-PCV13 serotypes. We also analyzed antimicrobial susceptibilities of glycopeptides, linezolid (LZD), and daptomycin (DAP) of isolated S. pneumoniae strains. All tested strains were susceptible to vancomycin, teicoplanin, LZD, and DAP. Especially. DAP demonstrated the best outcome among the tested antibiotics, with MIC90 of 0.094 μg/mL. Pneumococcal meningitis in children continues to persist and is difficult to control with the current conjugate vaccines. Therefore, it is important to monitor the serotype and antimicrobial susceptibility of S. pneumoniae strains isolated from patients with meningitis and accordingly reconsider the treatment strategy.

After the introduction of the 13-valent pneumococcal conjugate vaccine (PCV13), serotype replacement has occurred in Japan, and serotype 24 has become the most common serotype in paediatric invasive pneumococcal disease (IPD). To understand the characteristics of serotype 24-IPD in Japanese children in the post-PCV13 era, we conducted a retrospective study in children aged ≤15 years from 2010 to 2020 using a database of paediatric IPD surveillance in Chiba prefecture, Japan. We identified a total of 357 IPD cases and collected clinical information on 225 cases (24: 32 cases, non-24: 193 cases). Compared with the non-serotype 24-IPD, serotype 24-IPD was independently related to be <2 years of age [odds ratio (OR) 3.91, 95% confidence interval (CI) 1.47-10.44; P = 0.0064] and bacteremia (OR 2.28, 95% CI 1.01-5.13; P = 0.0475), as a result of the multivariate regression analysis. We also conducted a bacterial analysis, and the isolates of serotype 24-IPD had tendencies of PCG-susceptible (24: 100.0%, non-24: 61.3%; P < 0.0001) and macrolide-resistance (24: 100.0%, non-24: 87.3%; P = 0.0490). Their multilocus sequence typing was mostly ST2572 and the variants, which were unique to Japan. This tendency might have been a result of the progress made in the Japanese PCV13 immunisation programme.

Hematological malignancy and solid tumor are major risks for invasive pneumococcal disease. Thirteen-valent pneumococcal conjugate vaccine (PCV13) is recommended for immunocompromised patients aged 6 years and older and adults who had not received the vaccine previously. However, vaccination for these individuals is not publicly subsidized in Japan. We measured pneumococcal serotype-specific IgGs (Pn-IgGs) and opsonophagocytic activities (Pn-OPAs) against PCV13 serotypes (1, 3, 5, 6A, 7F, and 19A) in patients with hematological malignancies and solid tumors who were outside the recommended age range for routine vaccination at baseline and at 1 and 6 months after the first dose of PCV13. Pneumococcal serotype-specific memory B cells (Pn-MBCs) against serotype 3 were measured from a portion of the study samples. Thirty-seven patients (30 in the young patient group and 7 in the adult patient group) completed the study. Pn-IgGs were significantly elevated at 1 month post-vaccination and persisted in protection level for 6 months after the first vaccination against all six serotypes measured except serotype 3. Pn-OPAs were significantly elevated and persisted as well against all six serotypes. Pn-MBCs were measured in 10 patients, and 90% of them had at least one detectable Pn-MBC, and 70% of them showed an increased frequency of Pn-MBCs against serotype 3. No serious adverse events were observed up to 1 month after vaccination. PCV13 is thus safe and immunogenic, including against serotype 3, in patients with hematological malignancies and solid tumors outside the recommended age range for routine vaccination.

PURPOSE: The anticoagulant agent recombinant thrombomodulin (rTM) activates protein C to prevent excessive coagulation and also possibly regulates hyper-inflammation via neutralization of high-mobility-group B1 (HMG-B1). The glycocalyx layer in endothelial cells also plays a pivotal role in preventing septic shock-associated hyperpermeability. The present study examined the effect of rTM in a murine model of Streptococcus pneumoniae-induced sepsis. METHODS: Male C57BL/6N mice were injected intratracheally via midline cervical incision with 2 × 107 CFU of S. pneumoniae (capsular subtype 19A). Control mice were sham-treated identically but injected with saline. rTM (10 mg/kg) was injected intraperitoneally 3 h after septic insult. Blood concentrations of soluble inflammatory mediators (interleukin [IL]-1β, IL-6, IL-10, and tumor necrosis factor [TNF]-α) were determined using a microarray immunoassay. Serum concentrations of HMG-B1 and syndecan-1, as a parameter of glycocalyx damage, were determined by enzyme-linked immunosorbent assay. The glycocalyx was also evaluated with electron microscopy. The lungs were removed, and digested to cells, which were then stained with a mixture of fluorophore-conjugated antibodies. Anti-mouse primary antibodies included PE-Cy7-conjugated anti-CD31, AlexaFluor 700-conjugated anti-CD45, PerCP-Cy5.5-conjugated anti-CD326, APC-conjugated anti-TNF-α, PE-conjugated anti-IL-6, and PE-conjugated anti-IL-10. A total of 1 × 106 cells per sample were analyzed, and 2 × 105 events were recorded by flow cytometry, and parameters were compared with/without rTM treatment. RESULTS: The blood concentration of TNF-α was significantly reduced 24 h after intratracheal injection in S. pneumoniae-challenged mice treated with rTM (P = 0.016). Levels of IL-10 in the lung endothelium of rTM-treated S. pneumoniae-challenged mice increased significantly 12 h after intratracheal injection (P = 0.03). Intriguingly, serum HMGB-1 and syndecan-1 levels decreased significantly (P = 0.010 and 0.015, respectively) in rTM-treated mice 24 h after intratracheal injection of S. pneumoniae. Electron microscopy indicated that rTM treatment preserved the morphology of the glycocalyx layer in septic mice. CONCLUSIONS: These data suggest that rTM modulates local inflammation in the lung endothelium, thus diminishing systemic inflammation, i.e., hypercytokinemia. Furthermore, rTM treatment reduced serum syndecan-1 levels, thus preventing glycocalyx damage. The use of rTM to treat sepsis caused by bacterial pneumonia could therefore help prevent both excessive inflammation and glycocalyx injury in the lung endothelium.

Patients with asplenia are at high risks of severe infections caused by encapsulated bacteria, particularly Streptococcus pneumoniae. Thirteen-valent pneumococcal conjugate vaccine (PCV13) and 23-valent pneumococcal polysaccharide vaccine (PPSV23) are recommended for invasive pneumococcal disease prevention; however, little is known about the immunity to pneumococci in young patients with asplenia. We measured pneumococcal serotype-specific IgG (Pn-IgG) levels and pneumococcal opsonophagocytic activity (Pn-OPA) against some PCV13-contained serotypes (1, 3, 5, 6A, 7 F, 19A) in 23 young patients with asplenia using surplus serum samples. In this study, 5 and 13 patients had received PCV13 during routine immunizations and PPSV23, respectively; however, >5 years had passed since the last dose in most cases. The geometric mean concentrations (GMCs) of Pn-IgG in all study patients were not under the cutoff level against six serotypes, but they were lower than the those of age-matched healthy controls, as we have previously published. The patients who had received only PPSV23 had significantly lower GMCs against four serotypes (serotypes 1, 6A, 7 F, and 19A) than that of the patients who had received at least one PCV13 vaccination. The patients who had received only PPSV23 also had significantly lower geometric mean titers (GMTs) of Pn-OPA against all three serotypes we measured (serotypes 3, 5, and 19A) than that of the patients who had received at least one PCV13 vaccination. Our findings are useful data that can indicate insufficient immunity in young patients with asplenia against some PCV13 pneumococci serotypes and suggest the need for appropriate vaccinations in the post-PCV13 era.

肺炎球菌結合型ワクチンが保育園児の上咽頭保菌に与える影響、水平伝播の状況について調査する目的で、2017〜2019年度、足立区(3ヶ所)と国分寺市(1ヶ所)の保育園の年3回の保菌調査で、分離された肺炎球菌の血清型・薬剤感受性について調査を行った。2017年度、2018年度、2019年度の肺炎球菌分離株数は55株、69株、60株(うち1検体から2つの血清型株分離)であった。年度ごとの肺炎球菌分離率は、64〜67%と大きな違いは認めなかった。13価肺炎球菌結合型ワクチン(PCV13)含有血清型は、2017年度2株、2019年度1株で、いずれも血清型3であった。PCV13非含有血清型である15Aは2017年度、2018年度に多く、また、無莢膜株が2018年度に多く分離された。2019年度は10Aと34、35Bが増加していた。保育園の中では、年度により同じ血清型が多数分離される傾向があり、水平伝播が示唆された。PCG MIC≧2μg/mLの株は、15株あり、血清型15A(5株)、35B(3株)、10A(4株)、無莢膜株(3株)であった。同一の児から年複数回分離された血清型は7種類あり、そのうち34、10A、23Bは年間を通じて検出されていた。1〜3回目の採取時における肺炎球菌の有無と同胞の有無との関連について解析したところ、1、2回目は有意な関連が認められた。肺炎球菌の上咽頭への無症候性定着が侵襲性感染症の発症契機となること、今後、新しく開発された肺炎球菌結合型ワクチンの効果を予測する上においても、保菌調査による継続的な監視が必要である。(著者抄録)

The pneumococcal conjugate vaccines successfully decreased the incidence of invasive pneumococcal diseases and pneumococcal antibiotic resistance. However, they also led to serotype replacements. According to a report by the National Institute of Infectious Diseases (NIID) in 2017, 96% of pneumococcal isolates obtained from children with IPD aged < 5 years were non-PCV13 serotypes. Here, we report the case of a Japanese immunocompetent and vaccinated child who developed refractory meningitis caused by Streptococcus pneumoniae nonvaccine serotype 10A. PCR revealed genotypic penicillin-resistant Streptococcus pneumoniae (gPRSP) with triple mutations (pbp1a + 2b + 2x). Multilocus sequence typing identified the strain as a sequence type (ST) 11189. The ST11189 strain has not been reported in Japan, but it has recently been reported as a cause of invasive infections in Korea. The clinical course was complicated by the development of brain and subdural abscesses that necessitated prolonged antibiotic treatment and multiple burr hole drainages. Unfortunately, the neurological sequelae persisted. Continued molecular surveillance is needed for monitoring emerging virulent clinical strains.

症例は1歳5ヵ月男児で川崎病と診断され,入院日よりγグロブリン製剤投与を開始した。翌日に解熱し川崎病の症状は改善したが,入院時に実施した咽頭培養から,Neisseria meningitidis分離が報告された。ご両親に無症状でもN.meningitidisは検出されることがあることを説明するも不安が強く,除菌のための抗菌薬治療を行い,咽頭培養再検査,セカンドオピニオンのための他医療機関への受診も行った。後日,N.meningitidisと報告された菌株について16SrRNAおよびrecA遺伝子(recA protein)の塩基配列の相同性を検討した結果,N.polysacchareaと同定した。質量分析法を用いたことによるN.meningitidisの誤同定であった。(著者抄録)

We describe a patient with invasive Haemophilus influenzae type b (Hib) infection despite being completely immunized by a conjugate Hib vaccine. Although Hib vaccination has contributed to significant reduction in invasive Hib infection, there are some case reports of invasive Hib infections despite immunization. Immunoglobulin (Ig) deficiency is the main cause of primary vaccine failure, and IgG2 subclass deficiency is known to be the leading cause. A previously healthy 13-month-old boy visited the outpatient clinic with a 5-day history of fever (40.0 °C), cough, and vomiting, and was diagnosed with bacterial meningitis, purulent pericarditis, and arthritis. Hib was recovered from blood, cerebrospinal fluid, and pericardial fluid. Immunological examination revealed subnormal IgG and IgA titers at 13 and 17 months of age. Serum IgG2 titer was recovered at 17 months of age despite being low at 13 months. Comprehensive gene analysis for primary immunodeficiency syndromes (primary antibody deficiency, common variable immunodeficiency, and toll-like receptor abnormalities) were negative. The antibody titer against Hib [anti-polyribosylribitol phosphate (PRP) antibody] was lower than the long-term protective titer (1.0 μg/ml) at 13 months of age, but was reactively increased to 2.38 μg/mL two months after booster immunization. Transient hypogammaglobulinemia of infancy (THI) is described as an accentuation and prolongation of the physiologic Ig nadir that is normally observed during infancy and defined as low IgG and IgA levels in the first three years of life. We speculate that he developed an invasive Hib infection as a result of primary Hib vaccine failure caused by THI.

INTRODUCTION: In 2010, oral fluoroquinolone tosufloxacin (TFX) granules were released as the first oral respiratory quinolone for children in Japan. METHODS: To investigate the recent trend of H. influenzae strains with low susceptibility to quinolones in children, we analyzed the gene sequences of quinolone resistance-determining regions (QRDRs) of gyrA, gyrB, parC, and parE of 23 clinical isolates from 15 patients aged <15 years with an MIC of ≥0.5 μg/mL for TFX from 2010 to 2018. RESULTS: Amino acid substitutions were observed in both GyrA and ParC in 13 strains (81%, 13/16), except two strains with a TFX MIC of 0.5 μg/mL with amino acid substitution in only GyrA and one strain with a TFX MIC of 1 μg/mL with no amino acid substitution. Four ST422 strains were observed in 2018, the detection age range was wide (0-7 years), and the residential city was varied. A total of 3/15 patients had a clear history of TFX treatment. CONCLUSIONS: Even for the strain with an MIC of 0.5 μg/mL for TFX, it is highly possible that it harbors a mutation in gyrA, which is the first step toward quinolone resistance, and it may also harbor mutations in both gyrA and parC. Furthermore, several specific sequence type quinolone-resistant H. influenzae strains, particularly ST422, may be widespread among children in Japan. It is necessary to investigate changes in resistance both at the MIC and gene levels. The continuous monitoring of strains and the use of antimicrobial drugs in treatment should be carefully observed.

Japan has not been able to eliminate rubella; as a result, the large rubella epidemic has occurred. Considering the complicated history of the vaccine policy in Japan, some susceptible populations became infected with rubella, resulting in an outbreak. We conducted a large serosurveillance against rubella in Chiba city after initiating free rubella-specific antibody testing and an immunization campaign during 2018-2019. The total number of rubella specific antibody tests that was conducted in the nationwide campaign and Chiba city original campaign was 8277 and 6104, respectively. The proportion of participants with an antibody titer of ≤1:16 using the hemagglutination inhibition (HI) test was higher in those in their 20-30s. On the contrary, the proportion of participants with an antibody titer of <1:8 using the HI test was higher in men in their 40-50s. This discrepancy possibly reflects the complicated history of the vaccine policy. The number of participants in the nationwide immunization campaign in this city was 1517, whereas that in the Chiba city campaign was 3607. The Chiba city campaign was effective against women in their 20-30s (child-bearing generation); however, the nationwide campaign was not sufficiently effective against men in their 40-50s because many workers were did not visit medical facilities to receive the measles-rubella vaccine.

診断に骨シンチグラフィが有用であったMethicillin-sensitive Staphylococcus aureus;MSSAによる腸腰筋膿瘍の一例を経験した。症例は14歳女児,発熱と体動困難で前医を受診し,感染巣不明のMSSA菌血症として抗菌薬を2週間投与され退院となった。しかし,1週間後に発熱と体動困難が再燃し,当院へ入院した。精神発達遅滞のため,症状の把握が困難であったが,筋骨格系感染症を疑い骨シンチグラフィを施行したところ,右骨盤内に集積を認めた。その後MRIを施行し,右腸腰筋膿瘍および右腸骨,仙骨骨髄炎と診断した。洗浄ドレナージを施行し,同時に採取した膿汁よりMSSAを分離,6週間の抗菌薬投与により後遺症なく治癒した。腸腰筋膿瘍は,感染巣の特定に難渋することがある。治療方針や抗菌薬投与期間の決定のため,画像検査等積極的な感染巣の検索が必要である。(著者抄録)

Individuals with immunosuppressive condition have a high risk of invasive Haemophilus influenzae type b (Hib) infection. In Japan, routine Hib vaccination program for children under 5 years old was introduced in December 2008. However, the national policy does not make provision for individuals aged ≥5 years who have medical conditions associated with a high risk of invasive Hib disease to receive Hib vaccine. We measured serum anti-polyribosylribitol phosphate specific (anti-PRP) antibodies to Hib in patients aged ≥5 years with hematological malignancies and asplenia and evaluated their levels of anti-PRP antibodies in post administration of Hib vaccine era. A total of 65 patients (48 with hematological malignancies, and 17 with asplenia) were included in this study, of which 84% had not received Hib vaccine. In addition, 95.4% had short-term protective levels of anti-PRP antibodies (defined as ≥0.15 μg/mL) and 41.5% had long-term protective levels of anti-PRP antibodies (defined as ≥1.0 μg/mL). Five patients had low anti-PRP antibody levels despite a history of Hib vaccination. Our results suggest that young patients with underlying diseases such as hematological malignancies and asplenia may be at risk of invasive Hib disease. Hence, we recommend they should receive Hib vaccines even if they are over the age limit for routine Hib vaccination program.

INTRODUCTION: Neisseria lactamica is a commensal bacterium of the upper respiratory tract in humans and is closely related to Neisseria meningitidis. N. lactamica colonization may contribute to preventing N. meningitidis colonization and invasive meningococcal disease. However, the transference of antimicrobial resistance genes from N. lactamica to N. meningitidis has been reported. METHODS: In this study, we aimed to identify N. lactamica using matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) and performed multilocus sequence typing of seven N. lactamica strains isolated from Japanese children. We also analyzed the antimicrobial susceptibility of these strains and the mutations in their antimicrobial resistance genes (penA, gyrA, and parC). RESULTS: All the N. lactamica strains could be identified using MALDI-TOF MS. All strains were of different sequence types (STs), including five new STs. Five strains had intermediate susceptibility, two were resistant to ampicillin, and all had five out of the five known PBP2 mutations. Six strains were resistant to levofloxacin. Among the quinolone-resistant strains, three had GyrA mutations, and three had both ParC and GyrA mutations. CONCLUSIONS: N. lactamica STs may vary in Japanese children, and penicillin- and quinolone-resistant strains may be prevalent. We should pay attention not only to the drug resistance of N. meningitidis but also to the drug susceptibility of N. lactamica whose drug-resistance genes may transfer to N. meningitidis.

Although the pneumococcal conjugate vaccine (PCV) has decreased the incidence of invasive pneumococcal disease (IPD) in children, cases of IPD caused by non-PCV serotypes have been increasing. Here, we report two cases of bacterial meningitis caused by meropenem-resistant Streptococcus pneumoniae; in both the cases, 13-valent PCV (PCV13) had been administered. The isolated S. pneumoniae strains were non-PCV13 serotype 35B and resistant to penicillin G, cefotaxime, and meropenem. In addition, multilocus sequence typing (MLST) revealed the sequence type (ST) to be 558. In case 1, a 6-month-old girl recovered without sequelae after antibiotic therapy comprising cefotaxime and vancomycin, whereas in case 2, a 9-month-old boy was treated with an empirical treatment comprising ceftriaxone and vancomycin administration. However, maintaining the blood concentration of vancomycin within the effective range was difficult, due to which the antibiotics were changed to panipenem/betamipron. During the treatment, he presented with seizures, which were effectively controlled with antiepileptic drugs. The rate of incidence of penicillin-susceptible IPD has been substantially increasing after the introduction of PCV. However, an upsurge in IPD cases due to multidrug-resistant (MDR) serotype 35B has been reported in countries where PCV13 was introduced before introducing in Japan. Moreover, an increase in the proportion of MDR serotype 35B and decrease in the susceptibility to broad-spectrum antimicrobials, including meropenem, have been reported. Hence, the number of meningitis cases caused by MDR serotype 35B/ST558 may increase in the future.

The non-encapsulated Streptococcus pneumoniae (NESp) has emerged and increased in the clinical setting. The majority of NESp strains have been isolated from the nasopharynxes of healthy carriers and from respiratory specimens of patients with otitis media. NESp strains were shown to be more effective than encapsulated counterparts at forming biofilms. Therefore, NESp should become one of the leading causes of emerging refractory respiratory disease after the introduction of pneumococcal conjugate vaccines. We report the first case of multidrug-resistant - including fluoroquinolone-resistant - NESp isolated from the intrabronchial aspirate of a patient with pneumonia. Drug-resistant NESp infections can possibly emerge as a clinical problem and thus the continuous monitoring of NESp infections is of utmost importance.

Studies on community-acquired pneumonia (CAP) and pneumococcal pneumonia (PP) related to the 13-valent pneumococcal conjugate vaccine (PCV13) introduction in Asia are scarce. This study aimed to investigate the epidemiological and microbiological determinants of hospitalised CAP and PP after PCV13 was introduced in Japan. This observational hospital-based surveillance study included children aged ⩽15 years, admitted to hospitals in and around Chiba City, Japan. Participants had bacterial pneumonia based on a positive blood or sputum culture for bacterial pathogens. Serotype and antibiotic-susceptibility testing of Streptococcus pneumoniae and Haemophilus influenzae isolates from patients with bacterial pneumonia were assessed. The CAP hospitalisation rate per 1000 child-years was 17.7, 14.3 and 9.7 in children aged <5 years and 1.18, 2.64 and 0.69 in children aged 5-15 years in 2008, 2012 and 2018, respectively. There was a 45% and 41% reduction in CAP hospitalisation rates, between the pre-PCV7 and PCV13 periods, respectively. Significant reductions occurred in the proportion of CAP due to PP and PCV13 serotypes. Conversely, no change occurred in the proportion of CAP caused by H. influenzae. The incidence of hospitalised CAP in children aged ⩽15 years was significantly reduced after the introduction of PCV13 in Japan. Continuous surveillance is necessary to detect emerging PP serotypes.

The Japanese government suspended proactive recommendation of human papillomavirus (HPV) vaccination due to several reports of adverse events related to it in 2013. After that, the immunization rate of HPV vaccine quickly declined in Japan. Health science teachers (HSTs) are qualified and licensed teachers in charge of health care and health education for students in Japanese schools. HSTs have not recommended HPV vaccination to female students, since active governmental recommendation for HPV vaccination was halted for 5 y. We conducted a primary survey targeting HSTs (N = 39) and university students taking the HST training course (N = 123). In each group, awareness regarding HPV vaccine and disease burden was evaluated and factors related to and barriers to HPV vaccine recommendation were identified. The primary survey found that many HSTs and university students recognized their insufficient knowledge regarding the HPV vaccine. Based on the primary survey's results, infectious disease specialists, collaborating with Japanese HSTs, developed educational slide sets on HPV vaccine. A secondary survey was conducted before and after the lecture with HSTs (N = 162), where we evaluated their intelligibility and intention to recommend HPV vaccination for female students. In the post-lecture, secondary survey, the number of HSTs who recommended the HPV vaccine to their students had statistically increased from 76 before the lecture, to 103 (p < .05). An educational lecture using appropriate materials improved HSTs' vaccine confidence and intention to recommend the HPV vaccine to their students, verifying the study's hypothesis.

The prevalence of nonencapsulated Streptococcus pneumoniae (NESp) has increased with the introduction of pneumococcal conjugate vaccines in children; however, the bacteriological characteristics of NESp have not been sufficiently clarified. In this study, NESp strains isolated from the nasopharyngeal carriage of children from four nursery schools in Japan were analyzed for molecular type, antibiotic susceptibility, and biofilm productivity. A total of 152 putative S. pneumoniae strains were identified by optochin-susceptibility analysis, of which 21 were not serotypeable by slide agglutination, quellung reaction, or multiplex PCR. Among these 21 strains, three were lytA-negative and, therefore, not S. pneumoniae. The remaining 18 strains were positive for lytA, ply, pspK, and bile solubility and were confirmed as NESp. Therefore, the isolation rate of NESp in the S. pneumoniae strains in this study was 12.0% (18/149). Molecular-typing analyses classified five strains as two existing sequence types (STs; ST7502 and ST7786), and 13 strains formed four novel STs. Horizontal spread was suspected, because strains with the same ST were often isolated from the same nursery school. The NESp isolates were generally susceptible to most antimicrobials, with the exception of macrolides; however, all isolates possessed more than one abnormal penicillin-binding protein gene. Furthermore, NESp strains were more effective than encapsulated counterparts at forming biofilms, which showed obvious differences in morphology. These data indicated that NESp strains should be continuously monitored as emerging respiratory pathogens.

Introduction. Certain nontypeable Haemophilus influenzae cannot be assigned a sequence type (ST) by Multilocus Sequence Typing (MLST) due to the lack of the fucK gene, one of seven MLST loci in H. influenzae, which encodes a fucose-operon enzyme.Aims. To confirm whether the loss of fucK is also found in the encapsulated strains, we analysed clinical isolates of H. influenzae serotype e (Hie).Methodology. We conducted MLST, PFGE, and antimicrobial susceptibility tests of 45 Hie strains; the majority (n=43) were derived from respiratory samples of pediatric patients at Chiba Children's Hospital between 2000 and 2016. The two remaining strains were obtained from the blood of elderly patients with invasive H. influenzae diseases (IHiDs) between 2015 and 2016 at general hospitals. For the fucK-negative strains, PCR analysis for fucose operon was also performed.Results. Four STs (ST18, 122, 621 and 1758) were assigned to 13 strains, and remaining 32 (including one associated with IHiD) were fucK-negative, completely missing the fucose operon. The allelic profiles of six other loci were identical among 31 strains and to that of ST18, 122 and 621, and these strains were genetically closely related. Forty of 45 isolates were ampicillin-sensitive.Conclusions. The loss of fucK was frequently observed in clinical isolates of Hie from children. Moreover, fucK-negative Hie may be the cause of IHiD in adult patients. The majority of Hie, including fucK-negative strains, were shown to be clonally related and were ampicillin sensitive. This represents the first report examining fucK losses in encapsulated H. influenzae.

Introduction. In 2016-2017, there was an increase in the number of paediatric invasive pneumococcal disease (IPD) cases caused by Streptococcus pneumoniae serotype 12F in Chiba Prefecture, Japan. Serotype 12F is one of the major causative serotypes of IPD following the introduction of pneumococcal conjugate vaccine 13 (PCV13), and outbreaks of IPD caused by serotype 12F have recently been reported in several countries.Aim. Our goal here was to clarify the relationship among local outbreak strains and the outbreak strains in other countries, and for this we analysed clinical isolates of S. pneumoniae serotype 12F using several genetic identification methods.Methodology. All reported IPD cases caused by serotype 12F were reviewed and bacterial strains were collected and analysed. We also analysed S. pneumoniae serotype 12F strains isolated from other time periods, geographical areas, cases of adult IPD and respiratory specimens as control strains. Multi-locus sequence typing, PFGE and multi-locus variable number tandem repeat analysis (MLVA) were conducted on all isolates.Results. All 26 S. pneumoniae serotype 12F isolates, including control strains, belonged to a single sequence type (ST4846) that was the specific ST in Japan. All tested strains demonstrated five MLVA patterns and two PFGE patterns.Conclusion. We determined that the 2016-2017 outbreak of IPD in Chiba Prefecture was caused by clonally related isolates of serotype 12F. The continuous monitoring of IPD caused by serotype 12F is important for evaluating the impact of re-emerging pneumococcal serotypes following the PCV13 introduction era, and MLVA could be a useful tool for identification of outbreak strains.

Panton Valentine Leukocidin (PVL) is one of the many toxins produced by Staphylococcus aureus. In Japan, PVL-positive S. aureus strains are mainly methicillin-resistant S. aureus (MRSA). Data regarding PVL-positive methicillin-sensitive S. aureus (MSSA) are scarce. In this report, we describe a case of severe infection by PVL-positive MSSA. A 12-year-old healthy girl was admitted with high fever and pain in the lower back. Computed tomography revealed a diagnosis of psoitis and multiple venous thromboses. Blood cultures obtained after admission revealed infection with MSSA. Her fever continued despite adequate antibiotic therapy. On the fifth hospitalization day, she developed bladder dysfunction, and an abscess was noted near the third lumbar vertebra. She underwent an emergency operation and recovered. Bacterial analyses revealed that the causative MSSA was a PVL-producing single variant of ST8 (related to USA300clone), of sequence type 2149. PVL is known to cause platelet activation. This case demonstrates the need for detailed analyses of the causative strain of bacteria in cases of S. aureus infection with deep vein thrombosis, even in cases of known MSSA infection.

症例は新生児期に2度の遅発型B群溶連菌(Streptococcus agalactiae、Group B Streptococcus;GBS)菌血症を発症した女児。免疫学的素因のない正期産児であった。母体の産前GBSスクリーニングは陰性で、乳腺炎症状もなかったが、経過より経母乳感染が否定できないと考え、母乳培養を行った。児血液および母乳より発育したGBSの解析を行ったところ、血清型およびMLST(multi locus sequence typing)による遺伝子型が完全に一致した。経母乳感染の場合、通常の遅発型感染症よりも再発が多いことが知られているが、加えて本症例の血清型はIII型、遺伝子型はST17で、ともに高い再発率や侵襲性との関与が指摘されている血清型、遺伝子型であったことから、それも感染を繰り返した一因となったと考えている。本症例では、母乳栄養の中止と菌血症として通常の抗菌薬投与を行い、後遺症なく治癒し、再発もなく経過しているが、母体への抗菌薬投与を含めた発症時対応の標準化や、感染予防としての母体向けワクチンの導入など、今後の課題は多く、類似症例の蓄積が必須である。(著者抄録)

肺炎球菌による尿路感染症の2歳女児例の経験を契機に、当院での過去の尿検体から同菌を検出した症例を抽出した。2010年4月から2017年9月までの過去7年6ヵ月間の尿培養結果から、肺炎球菌が検出された症例を後方視的に抽出した。肺炎球菌検出率は過去7年6ヵ月間で4/5390件(0.07%)であった。尿路感染症と診断された症例は1例のみで、他は汚染菌とみなされた。汚染菌とみなされた3検体の2症例はいずれも尿路奇形を伴っていなかった。また、全例が複雑な腎尿路疾患を有しており、免疫抑制状態が示唆されたのは腎移植後の1例であった。全例、βラクタム系抗菌薬7〜14日間の投与で軽快し、外科的介入を要するなどの治療に難渋した例はなかった。本症例では複数菌が同時検出されており、菌量も最も少なく汚染菌との鑑別がより重要であった。

症例は6歳女児。短腸症候群のため10ヵ月時より中心静脈で栄養管理していた。肺炎球菌による菌血症で入院し、抗菌薬開始後解熱したが、肉眼的血尿と蛋白尿に加え、乏尿と顔面・四肢浮腫、高血圧、低補体血症を認めた。カテーテルを抜去したところ、速やかに解熱、蛋白尿は消失し、顕微鏡学的血尿のみ残存した。中心静脈カテーテル感染症に関連した腎炎では抗菌薬治療に加え、早期のカテーテル抜去が望ましいと考えられた。(著者抄録)

Invasive fungal infection (IFI) is a life-threating infectious disease in high-risk neonates. Strategies for the treatment and prevention of IFI in neonates in Japan remain unclear. We conducted a nationwide retrospective survey to determine IFI incidence between January 2014 and October 2015. Primary survey questionnaires were submitted to 309 medical facilities that regularly treat high-risk neonates. The questionnaire assessed IFI incidence during the study period, methods for preventing fungal infection in early delivery neonates, and methods for preventing mother-to-child fungal transmission. The secondary questionnaire was for facilities that had IFI cases and replied to the primary questionnaire. In total, 128 medical facilities (41.4%) completed the primary questionnaire, 17/128 facilities recorded 23 proven or probable IFI cases. Estimated annual IFI incidence was 0.33/1000 live births of hospitalized neonates. Patient data at IFI onset were available for all 23 patients. Birth weight was < 1000 g in 18 patients. Causative microorganisms were identified in 22 patients. Candida species (n = 21) were the most common pathogens, and one patient had mucormycosis. The mortality rate was 17.4%. Regarding neonatal fungal prophylaxis, 55/128 facilities (43.0%) reported administering therapy. The most frequently used prophylactic drugs were fluconazole, then micafungin. Fungal prophylaxis for mothers who showed fungal colonization was performed in 30/128 facilities (23.4%). Oxiconazole vaginal tablets were most commonly used as prophylaxis for high-risk mothers. In Japan, the diagnosis, treatment, and prevention of neonatal IFI varied. Continuous surveillance and treatment regimen for neonatal IFI are required to improve outcomes in high-risk neonates.

Haemophilus influenzae is a major pathogenic bacteria causing invasive disease, which is classified into six capsular serotypes (a-f) and non-typeable (NT) strains. Capsular serotyping of H. influenzae is traditionally determined by serological methods and more recently by PCR methods. However, these methods are time-consuming and expensive. In the present study, matrix-associated laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) was evaluated as an alternative method for capsular serotyping of H. influenzae clinical strains. We created an in-house database of all six serotypes and NT H. influenzae strains using the main spectrum creation standard method set to the default parameters in MADI-TOF MS. We evaluated the performance of the in-house database using 79 clinical strains already identified by PCR and 58 prospectively collected clinical strains. Measurements were performed using the Bruker MALDI BioTyper system. The peak list was matched against the reference library using the integrated pattern algorithm of the software. The best-matched spectrum was considered the serotyping result. All 137 test strains were correctly identified as H. influenzae using MALDI-TOF MS. The sensitivity and specificity for identification for type b, type e, and type f capsular serotypes and NT H. influenzae using MALDI-TOF MS were 100%/94.3%, 94.7%/97.9%, 97.4%/97.9%, and 85.5%/99.2%, respectively. Our findings indicate that MALDI-TOF MS is a useful alternative method for capsular serotyping of H. influenzae strains. This method is faster and more cost-effective than traditional methods and will therefore be useful for routine applications in clinical laboratories.

We report a case of mediastinal subcutaneous and multiple muscular abscesses caused by group B streptococcus serotype VIII in a type 2 diabetes mellitus patient. The patient arrived at the hospital with the chief complaint of immobility, and blood examination results suggested an acute infection and poorly controlled diabetes mellitus. Group B streptococcal bacteria were cultured from the patient's blood, and identified as serotype VIII upon further analysis. The patient recovered without any sequelae after percutaneous drainage, antibiotic therapy, and intensive glycemic control. Although the incidence of group B streptococcal infection in non-pregnant adults has recently increased in many developed countries, information on serotype VIII infection is quite limited. The reason is that serotype VIII group B streptococci are a Japan-specific serotype, and rarely cause invasive infections, even in Japan. Therefore, further surveillance and case reports should be documented in the future.

造血器腫瘍または固型腫瘍にて経過観察中の小児41名(5〜18歳)から血清試料を採取し、肺炎球菌PCV13(非PCV7)血清型に対する特異的抗体を測定した。患児はいずれもPCV13接種を受けていなかった。6つの血清型すべてについて患児のIgGレベルは同年齢の健常対照と比べて低かった。採血前6ヵ月以内に化学療法を受けた患児では他の患児と比べて血清型特異的IgGレベルが低かった。以上より、年齢を理由に定期的ワクチン接種を推奨されていない免疫不全状態の小児の多くにおいて、侵襲性肺炎球菌感染症の予防に十分なPCV13血清型特異的IgG値に達していないことが判明した。

Although invasive meningococcal disease is rare in Japan (0.028 cases per 100,000 population), its incidence is 10 times greater in many other countries. Colonization is a prerequisite for invasive meningococcal disease. However, no study in Japan has involved specifically analyzing the carriage rate of Neisseria meningitidis in children. During 5 months in 2015, the respiratory tract specimens of patients who presented to 3 hospitals with respiratory symptoms were cultured. The bacteria were identified in selective media using a meningococcal detection kit and the serogroup was identified using polymerase chain reaction analysis. In 389 patients aged ≤ 15 years with respiratory symptoms, the N. meningitidis isolation rate was 0.26% (1/389). The serogroup of the only child who tested positive was Y. In this study, we detected a low meningococcal isolation rate in pediatric patients. Due to increasing globalization, the risk of invasive meningococcal disease is likely increasing in Japan. Accordingly, invasive meningococcal diseases should be continuously monitored in Japan. Future large-scale studies should assess meningococcal isolation rates and corresponding serogroups.

<jats:title>ABSTRACT</jats:title><jats:p><jats:named-content content-type="genus-species">Haemophilus influenzae</jats:named-content>type b (Hib) conjugate vaccines have led to dramatic reductions in Hib disease among young children worldwide. Nontypeable<jats:named-content content-type="genus-species">H. influenzae</jats:named-content>(NTHi) is now the major cause of invasive<jats:named-content content-type="genus-species">H. influenzae</jats:named-content>infections. We investigated the clinical characteristics of invasive NTHi diseases among children in Japan, to clarify the pathogenicity of isolated NTHi strains. The mortality rate was 10.7%, with deaths occurring mainly among children with underlying comorbidities. Biotypes II and III were the most common, and most strains (64.3%) had multiple amino acid substitutions at the Asp-350, Ser-357, Ser-385, and/or Met-377 sites of penicillin-binding protein 3. Two strains were β-lactamase positive and ampicillin-clavulanate resistant. Biofilm indices varied widely, and IS<jats:italic>1016</jats:italic>was detected in 10.7% of the strains tested. Moreover, there was wide variation in the characteristics of invasive NTHi strains. NTHi strains, showing great genetic diversity, are responsible for most invasive<jats:named-content content-type="genus-species">H. influenzae</jats:named-content>infections in children in the postvaccine era. Continuous monitoring of NTHi strains responsible for invasive diseases in children is important to detect changes in the epidemiology of invasive<jats:named-content content-type="genus-species">H. influenzae</jats:named-content>infections in the postvaccine era.</jats:p>

Tosufloxacin (TFLX) is a fluoroquinolone antimicrobial agent. TFLX granules for children were initially released in Japan in 2010 to treat otitis media and pneumonia caused by drug-resistant bacteria, e.g. penicillin-resistant Streptococcus pneumoniae and beta-lactamase-negative, ampicillin-resistant Haemophilus influenzae. The evolution of bacterial resistance since TFLX approval is not known. To clarify the influence of quinolones administered to children since their approval, we examined the resistance mechanism of TFLX-resistant S. pneumoniae isolated from paediatric patients as well as patient clinical characteristics. TFLX-resistant strains (MIC ≥ 2 mg/L) were detected among clinical isolates of S. pneumoniae derived from children (≤15 years old) between 2010 and 2014. These strains were characterised based on quinolone resistance-determining regions (QRDRs), i.e. gyrA, gyrB, parC, and parE. In addition, the antimicrobial susceptibility, serotype, and multilocus sequence type of strains were determined, pulsed-field gel electrophoresis was performed, and patient clinical characteristics based on medical records were assessed for cases with underling TFLX-resistant strains. Among 1168 S. pneumoniae isolates, two TFLX-resistant strains were detected from respiratory specimens obtained from paediatric patients with frequent exposure to TFLX. Both strains had mutations in the QRDRs of gyrA and parC. One case exhibited gradual changes in the QRDR during the clinical course. This is the first study of quinolone-resistant S. pneumoniae isolated from children, including clinical data, in Japan. These data may help prevent increases in infections of quinolone-resistant S. pneumoniae in children; specifically, the results emphasise the importance of administering fluoroquinolones only in appropriate cases.

This study aimed to identify trends in frequency, serotype, and antimicrobial susceptibility of Streptococcus pneumoniae and Haemophilus influenzae isolated from middle ear fluid specimens of children aged≤15 years (mean, 2 years), before and after the introduction of the 7-valent pneumococcal conjugate vaccine (PCV7) and the H. influenzae type b vaccine, at a pediatric facility in Japan. Sixty-six S. pneumoniae and 88 H. influenzae strains were isolated from 820 middle ear fluid samples. Serotyping and antimicrobial susceptibility testing were performed. The study time-frame was divided into period 1 (2007-2010) and period 2 (2011-2014), according to the availability of vaccine public funding. The S. pneumoniae detection rate decreased from 9.6% in period 1-6.1% in period 2 (p = 0.042). PCV7 serotypes decreased from 56.8% to 9.1% (p = 0.0002). No significant change was observed for the 13-valent pneumococcal conjugate vaccine (PCV13) serotypes: 72.7% in period 1 and 59.1% in period 2. Penicillin-resistant strains (penicillin G-MIC ≥2 μg/mL) decreased from 25% to 4.5% (p = 0.038). Detection rates for H. influenzae did not change significantly: 10.3% in period 1 and 11.3% in period 2. Serotypes were mostly non-typeable: 97.9% in period 1 and 90.2% in period 2, and only one serotype b strain was isolated in each period. The frequency of ampicillin-resistant strains (MIC ≥4 μg/mL) did not change. These results show a preventative effect of PCV7 on otitis media due to S. pneumoniae. PCV7 was replaced with PCV13 in 2013 in Japan; therefore, a further decrease in pneumococcal otitis media is anticipated in the future.

Background Corynebacterium striatum was recently recognized as a potential pathogen of various infectious diseases. However, the clinical entity of this microorganism has not been clearly identified. Therefore, we analyzed C. striatum isolates from blood culture and explored their clinical determinants. Methods We reviewed the medical records of all patients from whom C. striatum isolates were recovered from blood culture for analysis of the patients' backgrounds and clinical course including response to antimicrobial therapy and prognosis. Results During the 5-year study period (January 2010 to December 2014), 24 C. striatum strains were isolated from blood samples, and the frequency of C. striatum bacteremia increased. The majority of the strains were multidrug resistant. All of the tested strains were susceptible to only vancomycin. The age at onset of C. striatum bacteremia encompassed all adult age groups, and at least one underlying condition was documented in all patients. Thirteen of the 24 patients were cured using appropriate antibiotics (true infection group) however, 11 of the 24 patients were cured using inappropriate antibiotic therapy or no antibiotics (contamination group). Malignancy and neutropenia significantly increased the odds of true C. striatum bloodstream infection. Conclusions The Corynebacterium species is often considered a contaminant when isolated in culture. Instead, particularly when the strain is isolated from blood, the species should be considered clinically relevant and identified to the species level in addition, antimicrobial susceptibility testing is recommended.

To our knowledge, this is the first report of the use of real-time reverse transcription-polymerase chain reaction to assess changes in viral load in a patient with congenital rubella syndrome (CRS). Rubella-specific antibody titers were also determined. The patient was a male neonate born to a primipara with rubella infection at 10 weeks of gestation. He had no symptoms at birth, but rubella virus was detected in his pharynx, blood, and urine. His mental and physical development was normal for 1 year however, he was diagnosed with deafness at 13 months of age. Thus, the patient was diagnosed with CRS. Rubella infection in the pharynx was almost constant until 5 months of age however, it increased dramatically at 6 months of age. No infection was detected at 13 months. Rubella-specific immunoglobulin M titer was consistently low until 9 months of age and then decreased gradually until it became negative at 20 months of age. Rubella-specific immunoglobulin G titer was high at birth. However, it decreased at 3 months and increased again at 4 months. This titer peaked at ?9 months and then decreased again at 13 months. This case shows that the period after the decline in maternal antibody titers, not the neonatal period, may be the most contagious period in patients with CRS.

A 16-year-old boy with chronic granulomatous disease presented with pneumonia and rib osteomyelitis. Emericella nidulans var. echinulata was isolated from his sputum. After starting voriconazole, Rasamsonia piperina was isolated from the rib swelling. A combination therapy of voriconazole and micafungin effectively eradicated this invasive mixed-mold infection. In immunocompromised patients, a precise pathogenic diagnosis is clinically useful for administration of an appropriate treatment regimen.

症例:32歳、外国人女性、肺結核の治療歴あり。経過:妊娠初期の喀痰検査で塗抹陰性、培養でMycobacterium tuberculosis陽性となり、多剤耐性菌と判明したため、当院を紹介受診した。経過中に気道症状なく、画像上も変化を認めなかった。妊娠中、結核治療は行わなかった。児は帝王切開で出生し、出生後は隔離管理を行った。児の先天性結核は認めず、児への予防投薬は行わなかった。母の治療開始まで母児隔離が望ましかったが現実的には困難であった。事前のスタッフへの空気感染対策指導により、施設内感染は認めなかった。まとめ:耐性菌であったことから治療の点や家族背景、言葉の面で対応に苦慮した。多剤耐性結核、超多剤耐性結核といった薬剤耐性結核菌が世界で問題になっている。今後、同様の症例の増加が懸念されるため国内における体制整備が必要である。(著者抄録)