石和田 稔彦

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)

INTRODUCTION: Community-acquired pneumonia (CAP) is one of the most common causes of pediatric infection requiring hospitalization. Antimicrobial resistance due to the inappropriate use poses a threat worldwide. Our objective is to analyze and optimize the trends of antibiotics used for pediatric inpatients with CAP in a claims database provided by the Ministry of Health, Labour and Welfare. METHODS: Our database randomly sampled 10% of the hospitalized patients every October from 2011 to 2014. Patients aged <15 years in whom antibiotic therapy was initiated within two days of admission were listed. Subsequently, we investigated the antibiotics administered on the first day of prescription. RESULTS: A total of 4,831 antibiotics were prescribed for 3,909 patients. Many patients aged ≤ five years were treated with β-lactams alone whereas many patients aged ≥ six years were treated with a single antibiotic, such as a macrolide, tetracycline, and quinolone, which covers atypical bacteria. Combination therapy was primarily used in children aged ≥ six years (nearly 30%); the main combination was a β-lactam and non-β-lactam covering atypical bacteria. Ampicillin-sulbactam was the most frequently prescribed β-lactam in children of all ages other than infants. Ampicillin, however, was most often prescribed in infants, but its usage rate was low at other ages. CONCLUSIONS: Antibiotics were appropriately prescribed and were similar to that recommended in the 2011 guidelines for pediatric inpatients with CAP. However, combination therapy was frequently prescribed in children aged ≥ six years. According to the revised guidelines in 2017, ampicillin should be used more frequently for patients hospitalized with CAP.

A nationwide surveillance of the antimicrobial susceptibility of pediatric patients to bacterial pathogens was conducted by Japanese Society of Chemotherapy, the Japanese Association for Infectious Diseases, and the Japanese Society for Clinical Microbiology in Japan in 2017. The isolates were collected from 18 medical facilities between March 2017 and May 2018 by the three societies. Antimicrobial susceptibility testing was conducted at the central laboratory (Infection Control Research Center, Kitasato University, Tokyo) according to the methods recommended by the Clinical Laboratory Standards Institute. Susceptibility testing was evaluated in 926 strains (331 Streptococcus pneumoniae, 360 Haemophilus influenzae, 216 Moraxella catarrhalis, 5 Streptococcus agalactiae, and 14 Escherichia coli). The ratio of penicillin-resistant S. pneumoniae was 0% based on CLSI M100-ED29 criteria. However, three meropenem or tosufloxacin resistant S. pneumoniae isolates were obtained. Among H. influenzae, 13.1% of them were found to be β-lactamase-producing ampicillin resistant strains, while 20.8% were β-lactamase non-producing ampicillin-resistant strains. No capsular type b strains were detected. In M. catarrhalis, 99.5% of the isolates were β-lactamase-producing strains. All S. agalactiae and E. coli strains were isolated from sterile body sites (blood or cerebrospinal fluid). The ratio of penicillin-resistant S. agalactiae was 0%, while that of extended spectrum β-lactamase-producing E. coli was 14.3%.

Community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) has become a pathogen of major importance in pediatric patients. CA-MRSA can cause skin and soft tissue infection in children and young active adults with no predisposing factors, and life-threatening infections such as meningitis or necrotizing pneumonia have been reported. We report here a case of CA-MRSA meningitis complicated by acute left middle cerebral artery (MCA) infarction and necrotizing pneumonia in a previously healthy 1-month-old Vietnamese boy. He was firstly treated with vancomycin, but changed to linezolid because of persistent fever and low vancomycin trough level. He recovered successfully with residual right-sided hemiparesis. The mode of transmission of CA-MRSA and the mechanism of cerebral infarction (thrombotic or embolic) were unknown. The isolate was genotyped as staphylococcal cassette chromosome (SCC) mec type V with a novel sequence type (ST) 5959 harboring the Panton-Valentine leukocidin (PVL) gene. ST 5959 is a double locus variant of ST 59, which is a major PVL-positive CA-MRSA strain isolated in invasive disease in Asian countries. This case report may serve as a warning about the dissemination of PVL-positive CA-MRSA in and around Japan, with the possibility of causing serious life-threatening disease. The potential of linezolid for the treatment of MRSA meningitis as one of the alternative MRSA therapeutic drugs is also discussed.

BACKGROUND: Because of the overabundance of vaccination information on the internet, in the media, and on social media, providing clear and correct information on immunization is critical for parental decision-making. In 2018, the Japan Pediatric Society created and distributed a Vaccine Information Statement (VIS) to provide appropriate immunization information to caregivers. The objectives of the present study were to evaluate the effect of the VIS on immunization rates, adherence to schedule, and parental understanding of immunization in Japan. METHODS: This cross-sectional study was conducted at 18 centers in 2 prefectures in Japan. Caregivers were assigned to an intervention group, which received the VIS and a questionnaire when their child reached the age of 1 month, and a control group, which received only the questionnaire. Using the self-reported questionnaires, we evaluated vaccination rates and schedule adherence at age 2 months, and parental knowledge, attitudes, and beliefs regarding immunization. Three months later, the questionnaires were returned, and the findings were compared between the 2 groups. RESULTS: We contacted 422 and 428 persons in the intervention and control groups, respectively, and 111/422 (26.3%) and 119/428 (27.8%) returned the surveys. Vaccination rates and adherence rates for the first dose of 4 recommended vaccines did not differ significantly (P > 0.25); however, there were some positive effects on items related to vaccine knowledge (P = 0.03), perceived benefits (P = 0.02), perceived barriers (P < 0.001), and perceived behavioral control (P = 0.01). CONCLUSION: The VIS improved parent comprehension of infant immunization. Future studies should examine if the effects of such an intervention persist and affect vaccine uptake throughout childhood.

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.

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.

生後1ヵ月健診の保護者を対象に、「知っておきたいわくちん情報」を配布する介入群111例と配布しない非介入群119例に分け、生後3ヵ月までの4ワクチン接種状況と保護者の予防接種に対する知識・態度・信念を比較検討した。その結果、4ワクチン接種率は2群間で有意差を認めなかった。保護者の態度と信念に関しては有益性の認知の1項目と自己効力感の1項目が、非介入群と比較して介入群で有意に高かった。障害の認知のスコアは非介入群と比べ、介入群で有意に低かった。今回の検討から、「知っておきたいわくちん情報」の配布により、保護者が乳児期の予防接種に関して肯定的に考え、その必要性を理解・納得し、接種の判断ができる可能性が示唆された。

© 2020, © 2020 Taylor & Francis Group, LLC. 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.

Aspergillosis is a rare fungal infection in newborns, and its morbidity and mortality are high. Voriconazole (VRCZ) is the first-line antifungal agent for invasive Aspergillus infection, but little data is available about its pharmacokinetics in infants. We report a case of a premature infant who developed ventriculitis due to Aspergillus fumigatus and received combination antifungal therapy including VRCZ. β-D glucan and Aspergillus antigen index were elevated in the cerebrospinal fluid (CSF). We titrated the dose of VRCZ by monitoring plasma and CSF concentrations. The CSF to plasma concentration ratio of VRCZ ranged from 0.47 to 1.36 (median 0.71). While VRCZ adequately penetrates the blood-brain barrier, its concentration is highly variable in infants.

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.