Kawasaki Disease and Vaccination: Prospective Case-Control and Case-Crossover Studies among Infants in Japan.

The causal effects of vaccines on Kawasaki disease (KD) remain elusive. We aimed to examine the association between vaccines administered during infancy and the development of KD in Japan. We conducted a multicenter prospective case-control study using questionnaires and compared the vaccination status of infants (age: 6 weeks to 9 months) who developed KD (KD group; n = 102) and those who did not develop KD (non-KD group; n = 139). Next, we performed a case-crossover study of 98 cases in the KD group and compared the status of vaccinations between the case and control periods. We also compared the incidence of KD in children for each 5-year period before and after the addition of new vaccines (2012-2013) using data from the Nationwide Survey of KD. In the case-control study, the vaccination status of the KD and control groups did not differ to a statistically significant extent. Multivariable analysis of the vaccination status and patient backgrounds showed no significant association between vaccination and KD development. In the case-crossover study, the status of vaccinations during the case and control periods did not differ to a statistically significant extent. In the analysis of data from the Nationwide Survey of KD, the incidence of KD in children of ages subject to frequent vaccination showed no significant increases in the latter five years, 2014-2018. Based on these prospective analyses, we confirmed that vaccination in early infancy did not affect the risk of KD.

Nationwide surveillance of bacterial pathogens isolated from children conducted by the surveillance committee of Japanese Society of Chemotherapy, the Japanese Association for Infectious Diseases, and the Japanese Society for Clinical Microbiology in 2017: General overview of pathogenic antimicrobial susceptibility.

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 ß-lactamase-producing ampicillin resistant strains, while 20.8% were ß-lactamase non-producing ampicillin-resistant strains. No capsular type b strains were detected. In M. catarrhalis, 99.5% of the isolates were ß-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 ß-lactamase-producing E. coli was 14.3%.

Drastic reduction in pneumococcal meningitis in children owing to the introduction of pneumococcal conjugate vaccines: Longitudinal analysis from 2002 to 2016 in Japan.

INTRODUCTION: The characteristics of pneumococcal isolates and their associations with outcomes in pediatric meningitis are unclear. This study aimed to clarify serotypes and resistance genotypes of Streptococcus pneumoniae from children with meningitis and evaluate the patient prognoses and backgrounds. METHODS: Large-scale surveillance was conducted from 2002 to 2016 through periods I-V. Serotypes and penicillin (PEN) resistance genotypes were analyzed for pneumococcal isolates (n = 459) and cerebrospinal fluid (CSF) samples (n = 25). Furthermore, underlying diseases (n = 251), prognoses (n = 202), and laboratory data were evaluated. RESULTS: The number of meningitis cases decreased drastically after the introduction of 7-valent pneumococcal conjugate vaccine (PCV7) to -53.6% and after switching to PCV13 to -70.2%. In particular, this reduction was apparent at ≤3 years of age. The proportion of the PCV7 serotype decreased sharply from 70.1% before introduction to 2.6% during period V; however, the non-vaccine type increased from 17.5% to 87.2%. The PEN resistance rate (gPRSP) was decreased from approximately 49% to 12.2% during period V. Among cases revealed prognosis, sequelae and mortality rates were 16.3% and 5.4%, respectively. The rate of the patients with underlying diseases was 26.3% and relatively high in ≥6 years. Laboratory data associated with a poor prognosis were low white blood cell count (<12.7 × 103/µL), low platelet count (<28.1 × 104/µL), low CSF-glucose (<36 mg/dL), and high CSF-protein (≥142 mg/dL). CONCLUSIONS: Changes in serotype prevalence warrant continuous monitoring to observe future trends of pneumococcal meningitis, and further developments in multivalent conjugate vaccines are required.

Changes in epidemiologic characteristics and antimicrobial resistance of Streptococcus pyogenes isolated over 10 years from Japanese children with pharyngotonsillitis.

Introduction. Pharyngotonsillitis caused by Streptococcus pyogenes (group A streptococci, or GAS) is among the most common infections treated with antibiotics in pediatric patients.Aim. This study aimed to analyse changes in molecular epidemiology and antibiotic susceptibility among GAS isolates in three study periods spanning 10 years.Methodology. GAS isolated from paediatric patients with pharyngotonsillitis during Period I (mid-2007 to 2008, n=235), Period II (2012, n=210), and Period III (2018, n=189) were analysed for emm type, multilocus sequence type (MLST), antibiotic susceptibility, and macrolide (ML)- and quinolone (QL)-resistance genes.Results. Over 20 % of isolates represented emm1 and emm12 types, remaining common in all three periods. Among other emm types, emm4 was common in Period I, emm28 and emm89 in Period II, and emm3 and emm89 in Period III. All isolates remained highly susceptible to penicillins and cephalosporins. Isolates possessing mefA, ermA, or ermB genes mediating ML resistance increased from 34.9 % in Period I to 60.9 % in Period II, but fell to 27.5 % in Period III. QL-resistant isolates with amino acid substitutions affecting ParC and/or GyrA gradually increased from 11.5 to 14.3 %. Specific sequence types identified by MLST and emm typing were associated closely with ML or QL resistance.Conclusion. Our findings indicate that even in ambulatory care, antibiotic choice for these infections should be based on rapid identification and characterization of causative pathogens.

Characterization and evaluation of a novel immunochromatographic assay for pharyngeal Mycoplasmapneumoniae ribosomal protein L7/L12 antigens.

Point-of-care testing for Mycoplasma pneumoniae infection may be ideal and useful because significant numbers of the cases will be seen as outpatients. Recently, a new immunochromatographic method (ICM) targeting M. pneumoniae ribosomal protein L7/L12 (RP-L7/L12) in pharyngeal swabs became available in Japan, although clinical data and basic information regarding efficacy and characterization of this ICM are limited. The present study examined the fate of M. pneumoniae RP-L7/L12 during in vitro growth and the correlation between M. pneumoniae concentration in clinical specimens and the sensitivity of the ICM test. The usefulness of the ICM was investigated in patients suspected of having M. pneumoniae pneumonia and upper respiratory tract infection (137 children and 39 adults). The limit of detection for the ICM test was 1.1×104 c.f.u. ml-1 of M. pneumoniae. Bacterial production of RP-L7/L12 correlated positively with the viable M. pneumoniae concentration in vitro; antigen was then degraded in culture broth, with an in vitro half-life of approximately 2 days. Five other Mycoplasma spp. and 14 representative respiratory pathogens were ICM assay negative at bacterial concentrations of 106 c.f.u. ml-1. The clinical sensitivity and specificity of the ICM assay were 57.1 % (20/35) and 92.2 % (130/141), respectively, in comparison with bacterial culture. Clinical specimens containing ≥106 c.f.u. ml-1 of M. pneumoniae burden were ICM positive in 13 of 18 cases (72.2 %). The ICM is a poorly sensitive but reasonably specific means for detecting M. pneumoniae infections.

Eculizumab in the treatment of atypical hemolytic uremic syndrome in an infant leads to cessation of peritoneal dialysis and improvement of severe hypertension.

BACKGROUND: Severe hypertension (HTN) and acute kidney injury frequently associated with atypical hemolytic uremic syndrome (aHUS) were refractory to various therapies in the pre-eculizumab era. Here we report the case of a 4-month-old boy who developed aHUS presenting with undetectable C3 protein, no predisposing mutations in complement factors, and no antibodies against factor H. METHODS: Repeated plasma infusions and nine sessions of plasmapheresis were ineffective. The patient initially required continuous hemodiafiltration and thereafter peritoneal dialysis. Despite vigorous antihypertensive treatment and improved fluid overload with dialysis, HTN persisted. His low C3 level (<20 mg/dl) suggested unrestricted complement activation. Therefore, based on the suspicion of unrestricted complement cascade in the pathogenesis, treatment with eculizumab, a human anti-C5 monoclonal antibody, was initiated with the aim of controlling disease activity. RESULTS: Eculizumab therapy resulted in the control of severe HTN and cessation of peritoneal dialysis. CONCLUSIONS: This infant with HTN and acute kidney injury associated with aHUS was treated successfully with eculizumab.

A new method for the detection of neutralizing antibodies against mumps virus.

Neutralization test is the most reliable method of evaluating immunity against viral diseases but there is no standard procedure for mumps virus, with tests differing in the infectivity of the challenge virus, 50% plaque reduction or complete inhibition of cytopathic effects (CPE), and usage of complement. A reliable, easy, and simple neutralization test for mumps virus was developed in this study. A recombinant mumps virus expressing GFP was generated as a challenge virus. Complement was added to the neutralizing mixture at 1∶200 when stocked serum samples were used. Neutralizing antibody titers were expressed as the reciprocal of the highest dilution that did not exceed two-fold of FU values (GFP expression) of the cell control wells. A total of 1,452 serum samples were assayed by inhibition of GFP expression in comparison with those examined by conventional 100% inhibition of CPE. 1,367 (94.1%) showed similar neutralizing antibody titers when examined by both methods. The GFP expression inhibition assay, using a recombinant mumps virus expressing GFP, is a simple and time- saving method.

Antibiotic susceptibility in relation to genotype of Streptococcus pneumoniae, Haemophilus influenzae, and Mycoplasma pneumoniae responsible for community-acquired pneumonia in children.

Streptococcus pneumoniae, Haemophilus influenzae, and Mycoplasma pneumoniae are the main pathogens causing community-acquired pneumonia (CAP). We identified S. pneumoniae (n = 241), H. influenzae (n = 123), and M. pneumoniae (n = 54) as causative pathogens from clinical findings and blood tests from pediatric CAP patients (n = 903) between April 2008 and April 2009. Identification of genes mediating antimicrobial resistance by real-time PCR was performed for all isolates of these three pathogens, as was antibiotic susceptibility testing using an agar dilution method or broth microdilution method. The genotypic (g) resistance rate was 47.7 % for penicillin-resistant S. pneumoniae (gPRSP) possessing abnormal pbp1a, pbp2x, and pbp2b genes, 62.6 % for ß-lactamase-nonproducing, ampicillin-resistant (gBLNAR) H. influenzae possessing the amino acid substitutions Ser385Thr and Asn526Lys, and 44.4 % for macrolide-resistant M. pneumoniae (gMRMP) possessing a mutation of A2063G, A2064G, or C2617A. Serotype 6B (20.3 %) predominated in S. pneumoniae, followed by 19F (15.4 %), 14 (14.5 %), 23F (12.0 %), 19A (6.2 %), and 6C (5.4 %). Coverage for the isolates by heptavalent pneumococcal conjugate vaccine (PCV7) and PCV13, respectively, was calculated as 68.5 and 80.9 %. A small number of H. influenzae were identified as type b (6.5 %), type e (0.8 %), or type f (0.8 %); all others were nontypeable. Proper use of antibiotics based on information about resistance in CAP pathogens is required to control rapid increases in resistance. Epidemiological surveillance of pediatric patients also is needed to assess the effectiveness of PCV7 and Hib vaccines after their introduction in Japan.

A practical approach estimating etiologic agents using real-time PCR in pediatric inpatients with community-acquired pneumonia.

To evaluate pathogens in pediatric inpatients with community-acquired pneumonia (CAP), an Acute Respiratory Diseases Study Group organized by ten Japanese medical institutions devised a rapid, reliable process based on real-time PCR results in nasopharyngeal swab samples plus admission blood test results. From April 2008 to April 2009, we enrolled 903 children with CAP based on chest radiographs and clinical findings who were hospitalized within 5 days of onset. Comprehensive real-time PCR was used to detect 6 bacteria and 11 respiratory viruses. The swab specimens also were used for bacterial cultures. After initial determination of presence or absence of viral and mycoplasmal infections, significant bacterial contributions were defined by bacterial identification, clinical efficacy of antimicrobial agent, and reference to blood test results. Children were stratified by age: below 1 year, 1 year, 2-5 years, or at least 6 years old. Among patients studied, 34.4 % were diagnosed with viral infection; 21.8 %, bacterial infection; 17.5 %, viral/bacterial co-infection; 5.9 %, mycoplasmal infection; 0.3 %, mycoplasmal/bacterial co-infection; and 1.7 %, viral/mycoplasmal co-infection. The remaining 18.4 % had unknown pathogens. Purely viral infection was suggested mainly in infants younger than 1 year; mycoplasmal infection typically occurred in children at least 6 years old. Our results suggest usefulness of real-time PCR for nasopharyngeal samples together with blood tests in estimating etiologic agents in clinical settings.

Antibodies against mumps virus component proteins.

The neutralization (NT) test is regarded as the most reliable method for detection of protective antibodies, but is labor-intensive and time consuming. Enzyme-linked immunosorbent assay (EIA) is frequently used in sero-epidemiological studies because of its simplicity and ease of use. In this study, immunofluorescent (IF) antibodies against nucleocapsid (N), fusion (F), and hemagglutinin-neuraminidase (HN) proteins were investigated in comparison with NT and EIA antibodies. The antibody against N protein was dominant in serum samples obtained from patients with a previous history of mumps infection. Titers of antibodies against F and HN proteins were very low. Many serum samples were positive for EIA but negative for NT, and no significant correlation was noted between NT and EIA antibodies. Among the three component proteins, correlation of EIA and IF antibodies with N protein was relatively good. After vaccination with mumps vaccine, EIA positivity was closely related to the IF antibodies against N protein, and after vaccination NT-positive sera became positive for IF antibodies against F and HN proteins. IF antibodies against F and HN proteins were considered to have a strong association with NT antibodies, and those against N protein were considered to have a strong association with EIA antibodies.

Association between the number of blood cultures and appropriateness of care for suspected bacteremic urinary tract infection in the elderly.

The objective of this study was to evaluate the association between the number of blood cultures collected and the appropriateness of care for suspected bacteremic community-acquired urinary tract infection (UTI) in the elderly. We retrospectively evaluated the medical records of 129 patients with UTI > 65 years old admitted to a large community-based training hospital in Japan from 1 January 2006 to 31 December 2009. We assessed the association between the number of blood cultures collected and the appropriateness of care received, as well as other factors. Two-thirds of the patients were women, and patients > 85 years old accounted for 45.0% of the cases. Most of the organisms isolated from the urine and blood were Escherichia coli (65.4-67.0%). More than two blood cultures were collected 79.1% of the time, and 66.7% of the cases were evaluated as having been treated appropriately. The appropriateness of care was not significantly related to the number of blood cultures. The appropriateness of care received in the general internal medicine department was significantly higher (p = 0.016) than that in other departments. Thus, the appropriateness of care for suspected bacteremic UTI in the elderly was not significantly associated with the number of blood cultures. However, the department of hospitalization may have influenced the appropriateness of care.

Characteristic findings of pediatric inpatients with pandemic (H1N1) 2009 virus infection among severe and nonsevere illnesses.

We analyzed the clinical features of inpatients at a Japanese pediatric department who were infected with pandemic (H1N1) 2009 virus. Study participants included 46 children hospitalized from July 2009 to January 2010. Infection with the virus was confirmed using real-time reverse transcriptase polymerase chain reaction (RT-PCR). The epidemic month was October 2009; 34 patients were boys, and median age was 7 years. Pandemic influenza-associated respiratory diseases included pneumonia (n = 42), bronchitis (n = 3), and pharyngitis (n = 1). The median time from onset to admission was 3 days. Children were divided into those with severe (n = 32) versus nonsevere illnesses (n = 14) according to Japanese guidelines. Significant features in the severe group were younger age, previous asthmatic attack, exacerbation of asthma, decreased oxygen saturation, elevated white blood cell/neutrophil counts and serum lactate dehydrogenase, and longer times from admission to being afebrile and discharged. Both groups showed lymphopenia at admission. Additional infection with Streptococcus pneumoniae was frequent in the severe group. Whereas 44 patients received antiviral therapy (median times from onset to initiation 2 days), 32 received antibiotics (median duration 7 days). All children recovered, with a median hospital stay of 8 days. Our observations suggest that history of asthma and preschool age might be risk factors for severe illness. Prompt initiation of antiviral and antibiotic treatments should be considered to prevent development of severe illness.

[Analysis of clinical features of community-acquired pneumonia caused by pediatric respiratory syncytial virus and human metapneumovirus].

We retrospectively reviewed the background, clinical features, blood tests, and complications in the 720 children seen for acute respiratory tract infection from July 2004 to December 2005. Of these, 75 (10.5%) were diagnosed with pneumonia due to respiratory syncytial virus (RSV) and 19 (2.6%) with pneumonia due to human metapneumovirus (hMPV) based on multiplex PCR analysis of nasopharyngeal samples. RSV was PCR-positive mostly in winter, -from November to January-, and hMPV mostly in spring, -from March to June. The mean RSV pneumonia group age was 1.3 +/- 1.4 years and in the hMPV pneumonia group 3.0 +/- 3.1 years, showing a statistically significant differences in the age of virus onset. Clinically the RSV group showed more rhinorrhea and wheezing (p < 0.05) and the hMPV group a higher maximum body temperature and a longer wheezing duration (p < 0.05). Fever, cough, vomiting, diarrhea, fever frequency, and C-reactive protein level were similar in both groups (p > 0.05). Complication prevalence was 49.3% in the RSV group and 42.1% in the hMPV group. Acute otitis media was seen more often in the RSV group (32.0%) and febrile convulsion more often in the hMPV group (15.8%) (p > 0.05). These findings may be helpful in clinically diagnosing community-acquired pneumonia due to RSV or hMPV.

[A 14-year-old healthy boy with splenic abscess due to Salmonella enterica serovar Senftenberg].

Salmonella enterica serovar Senftenberg may very rarely cause splenic abscess, which can be diagnosed using gallium scintigraphy and drained. A 14-year-old boy admitted for stomachache, diarrhea and fever and diagnosed from his symptoms as having enteritis did not respond when treated with fosfomycin, meropenem, and clindamycin. A low-density splenic area seen in abdominal computed tomography on admission did not show contrast medium enhancement. Gallium scintigraphy on hospital day 10, however, showed abnormal splenic accumulation confirming the splenic abscess diagnosis, after which we punctured and drained the abscessout. S. Senftenberg was isolated from pus aspirated pus from the abscess, after which responded well to ceftriaxone and levofloxacin. Follow-up gallium scintigraphy on hospital day 24 showed that the abnormal splenic accumulation had disappeared, after which he has been followed up with abdominal ultrasonography and blood tests as an outpatient. He has experienced no relapse of splenic abscess.

A comparative clinical study of macrolide-sensitive and macrolide-resistant Mycoplasma pneumoniae infections in pediatric patients.

In recent years, the increased prevalence of macrolide-resistant Mycoplasma pneumoniae (MR-M. pneumoniae) has become a significant issue in Japan. We isolated 94 strains of M. pneumoniae, and determined the minimum inhibitory concentrations (MICs) of macrolides and other antimicrobial agents for these strains. We also performed a comparative clinical evaluation of macrolide efficacy for cases of MR-M. pneumoniae infections and cases of macrolide-sensitive Mycoplasma pneumoniae infections (MS-M. pneumoniae). Of the 94 isolates of M. pneumoniae, 64 (68.1%) were classified as MS-M. pneumoniae and 30 (31.9%) as MR-M. pneumoniae strains. The clinical study included an assessment of 47 pediatric cases of MS-M. pneumoniae and 22 pediatric cases of MR-M. pneumoniae. The patient demographics, such as sex, age, the period from the onset of the infection to the first examination, laboratory findings, diagnosis, and the severity of symptoms, showed no significant difference between the two study groups. However, the efficacy of macrolide treatment was 91.5% for MS-M. pneumoniae and 22.7% for MR-M. pneumoniae, a statistically significant difference (P < 0.01). Although M. pneumoniae infection is generally considered a treatable condition, the increasing prevalence of macrolide-resistant strains of M. pneumoniae has become a significant clinical issue in pediatric patients, and it is therefore necessary to give careful consideration to the appropriate antimicrobial therapy for MR-M. pneumoniae infection.

Increased macrolide resistance of Mycoplasma pneumoniae in pediatric patients with community-acquired pneumonia.

Among 380 Mycoplasma pneumoniae isolates from 3,678 pediatric patients with community-acquired pneumonia, 50 macrolide-resistant strains had an A2063G transition in domain V of the 23S rRNA, whereas 5 had an A2064G transition. These resistant strains increased rapidly from April 2002 to December 2006.

[Influenza C virus isolated in Hiroshima Prefecture during the 1999/2000 winter season--a clinical and epidemiological study].

Influenza C virus (Inf. C) is one of pathogens of human respiratory tract infection and prevalent throughout the world at an early stage in life. However, Inf. C has been isolated only accidentally and there have been few reports on its clinical and epidemiological features. From November 1999 to March 2000, Inf. C was isolated from clinical specimens (throat swabs) of 4 pediataric patients with respiratory tract illness at Hiroshima Prefectural Hospital and was isolated in 4 peditaric patients at the other medical institutions in Hiroshima prefecture. There were no differences in clinical features including duration of illness, duration of fever, maximum body temperature between 4 patients with Inf. C infection and patients with influenza A (H1N1 and H3N2) and influenza B infection from 1992 to 2000. We investigated geographical distribution of patients with inf. C infection and analyzed for antigenic characteristics with a set of monoclonal antibodies against hemagglutinin-esterase glycoproteins. The data suggested that at least two antigenically different Inf. C prevalented in a region during winter from 1999 to 2000.

[The first report of an epidemic of human metapneumovirus infection in Japan: clinical and epidemiological study].

Human metapneumovirus (hMPV) was newly discovered as a pathogen in 2001 and is thought to be associated with respiratory disease. To elucidate the prevalence and clinical significance of hMPV among children, we investigated the positive cases of hMPV-RNA by reverse transcription-polymerase chain reaction (RT-PCR) in their nasopharyngeal specimens collected from January to August 2003 in Hiroshima Prefecture, Japan. Our prospective study revealed 77 hMPV-positive cases among 377 children with acute respiratory diseases. Clinical diagnoses of 77 hMPV-positive cases were as follows; bronchitis (33.8%), pneumonia (24.7%), acute respiratory illness (19.5%), asthmatic bronchitis (11.7%) and bronchiolitis (5.2%). The most common symptoms were cough (97.4%), high fever (94.8%) and rhinorrhea (76.6%). Most of the hMPV-positive cases were identified in the spring (between March and May), indicating the presence of an epidemic of hMPV infection in Hiroshima Prefecture. Phylogenetic analysis of the amplified F gene of hMPV isolates revealed that hMPV strains were divided into two genotypes and that their simultaneous circulation occurred within the same epidemic area of Hiroshima Prefecture.

[Two siblings with allergic purpura following Salmonella O9 enterocolitis].

Two siblings with allergic purpura after Salmonella O9 infection were reported. A girl (patient 1) aged 4 years and 4 months started to have knee joint pain and abdominal pain followed by purpura of the lower extremities and was referred to us for treatment of allergic purpura. She had contracted enterocolitis one month before visiting our hospital and Salmonella enteritidis was identified. During the course of the illness she had nephritis associated with allergic purpura. However, she made a favorable progress and proteinuria and hematuria disappeared within 6 months. A boy (an elder brother of patient 1) aged 6 years was admitted to our hospital because of the allergic purpura. He similarly had contracted Salmonella enterocolitis. He had severe gastro-intestinal symptoms including abdominal pain, vomiting and bloody stool, which rapidly subsided after initiation of treatment with intravenous hyperalimentation combined with prednisolone. It is possible that allergic purpura in our patients was closely associated with Salmonella enteritidis infection. Further accumulation of cases is a requisite to clarify an association of Salmonella enteritidis infection with allergic purpura and pathogenesis of allergic purpura.