Published papers

BACKGROUND: Acute otitis media is a leading cause of childhood morbidity and antibiotic prescriptions. We examined etiologic changes in acute otitis media after introduction of 13-valent pneumococcal conjugate vaccine as routine immunization for Japanese children in 2014. Serotypes, resistance genotypes, antibiotic susceptibilities and multilocus sequence typing of pneumococcal isolates were also characterized. METHODS: Otolaryngologists prospectively collected middle ear fluid from 582 children by tympanocentesis or sampling through a spontaneously ruptured tympanic membrane between June 2016 and January 2017. Causative pathogens were identified by bacterial culture and real-time polymerase chain reaction for bacteria. Serotypes, resistance genotypes, sequence types and susceptibilities to 14 antimicrobial agents were determined for pneumococcal isolates. RESULTS: At least 1 bacterial pathogen was identified in 473 of the samples (81.3%). Nontypeable Haemophilus influenzae (54.8%) was detected most frequently, followed by Streptococcus pneumoniae (25.4%), Streptococcus pyogenes (2.9%) and others. Pneumococci of current vaccine serotypes have decreased dramatically from 82.1% in 2006 to 18.5% (P < 0.001). Commonest serotypes were 15A (14.8%), 3 (13.9%) and 35B (11.1%). Serotype 3 was significantly less frequent among children receiving 13-valent pneumococcal conjugate vaccine compared with 7-valent pneumococcal conjugate vaccine (P = 0.002). Genotypic penicillin-resistant S. pneumoniae accounted for 28.7%, slightly less than in 2006 (34.2%; P = 0.393); the penicillin-resistant serotypes 15A and 35B had increased. Serotypes 15A, 3 and 35B most often belonged to sequence types 63, 180 and 558. CONCLUSIONS: Our findings are expected to assist in development of future vaccines, and they underscore the need for appropriate clinical choice of oral agents based on testing of causative pathogens.

© 2018, Centers for Disease Control and Prevention (CDC). All rights reserved. To clarify year-to-year changes in capsular serotypes, resistance genotypes, and multilocus sequence types of Streptococcus pneumoniae, we compared isolates collected from patients with invasive pneumococcal disease before and after introductions of 7-and 13-valent pneumococcal conjugate vaccines (PCV7 and PVC13, respectively). From April 2010 through March 2017, we collected 2,856 isolates from children and adults throughout Japan. Proportions of PCV13 serotypes among children decreased from 89.0% in fiscal year 2010 to 12.1% in fiscal year 2016 and among adults from 74.1% to 36.2%. Although nonvaccine serotypes increased after introduction of PCV13, genotypic penicillin resistance decreased from 54.3% in 2010 to 11.2% in 2016 among children and from 32.4% to 15.5% among adults. However, genotypic penicillin resistance emerged in 9 nonvaccine serotypes, but not 15A and 35B. Multilocus sequence typing suggested that resistant strains among nonvaccine serotypes may have evolved from clonal complexes 156 and 81. A more broadly effective vaccine is needed.

© 2018 Oto-Rhino-Laryngological Society of Japan Inc. All rights reserved. Thirteen-valent pneumococcal conjugate vaccine (PCV13) is now widely used in many countries. Widespread use of the vaccine, which has been dramatically effective, has changed the epidemiology of pneumococcal infection. Streptococcus pneumoniae is one of the causative pathogens of acute otitis media (AOM), and its change may influence both the clinical features and treatment of this disease. We conducted a nationwide survey in Japan from July 2016 to March 2017 to elucidate the current epidemiologic profile of AOM after the introduction of PCV13. We analyzed the bacterial pathogens, pneumococcal serotypes, and patient background factors in 529 children with AOM (97% of them had received at least 1 PCV dose). The most frequently detected bacterial pathogen was Haemophilus influenzae (57%), followed by Streptococcus pneumoniae (26%), Staphylococcus aureus (8%), Group A streptococcus (3%), and Moraxella catarrhalis (1%). For the case of Streptococcus pneumoniae, the most frequent serotype was 15A (15%), followed by 35B (12%), 3 (11%), 10 A (9%), and 15B (9%), indicating that the frequency of the PCV13 serotypes had decreased to 16%. In regard to the patient background factors, 61% were aged less than 2 years, 81% had severe AOM, 45% had experienced recurrent or/and protracted otitis media, 72% attended day-care centers, and 55% had associated rhinosinusitis. Antibacterial agents recommended by the Clinical Practice Guidelines for Diagnosis and Management of AOM in Children in Japan were administered to 97% of the patients, and the cure rate of first-line treatment was approximately 67%. With the widespread use of PCV13 in Japan, Haemophilus influenzae has become the predominant causative pathogen of AOM, although there have been no apparent changes of the patient background factors or efficacy of treatment. When treating AOM today, it is important to select therapy in the conventional way, i.e., based on the patient background factors and drug susceptibility profile of the causative pathogens, keeping in mind that Haemophilus influenzae has become the predominant causative pathogen.

© 2019 Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases Acute otitis media (AOM) occurs commonly in pediatric populations. We examined resistance genotype, antibiotic susceptibility, quinolone (QL) resistance, and multilocus sequence type (MLST) among Haemophilus influenzae isolates causing AOM following introduction of pneumococcal conjugate vaccines in Japan. The AOM surveillance group included 69 participating otolaryngologists. Causative pathogens isolated from middle ear fluid (MEF) samples collected from 582 children with AOM were identified using both bacterial culture and real-time PCR. H. influenzae isolates among these pathogens were characterized by capsular type, resistance genotype, antibiotic susceptibility, QL resistance, and MLST. In 2016, H. influenzae was identified in 319 samples (54.8%), among which 72.4% (n = 231) tested positive by both culture and PCR; remaining H. influenzae cases were only PCR-positive. This proportion of H. influenzae positivity has increased significantly from 41.2% in 2006 (p < 0.001). Among culture-positive strains, genotypic β-lactamase-nonproducing ampicillin (AMP)-resistant (gBLNAR) strains were frequent (63.2%), with β-lactamase-nonproducing AMP-susceptible (gBLNAS) strains accounting for only 24.2%. Susceptibilities of gBLNAR to oral antimicrobials were best for tosufloxacin, followed by cefditoren and tebipenem; MIC 90 s were 0.031 μg/mL, 0.5 μg/mL, and 1 μg/mL, respectively. In 7 gBLNAR isolates (3.0%), QL susceptibility was low, owing to amino acid substitutions in GyrA and/or ParC. Sequence types identified numbered 107, including 28 that were new. Prevention of further increases in resistance to antimicrobial agents will require antibiotic selection based on characterization of causative pathogens in clinical practice.

© 2018 The Authors. PURPOSE: β-lactamase-negative ampicillin-resistant (BLNAR) Haemophilus influenzae is frequently isolated from respiratory samples and is particularly problematic in Japan. The aim of this study was to characterize circulating isolates of H. influenzae genotypically by BLNAR-PCR and multilocus sequence typing (MLST), and to determine any associations between them. METHODS: H. influenzae isolates (n=191) were collected from paediatric patients (1 month to 12 years old) between 2000 and 2011 for three types of infections: pneumonia (n=61), acute otitis media (AOM) (n=68) and meningitis (n=62). All were characterized for capsular type by agglutination tests, and for β-lactam resistance by real-time PCR. The sequence types (STs) determined by MLST were analysed using eburst v3. RESULTS: Eighty-eight out of 191 (46.1 %) H. influenzae isolates were BLNAR by PCR; 37 of 61 (60.7 %) from pneumonia; 33 of 68 (48.5 %) from AOM and 18 of 62 (29.0 %) from meningitis cases. MLST identified 40 and 44 STs among isolates from pneumonia and AOM, respectively. BLNAR were found in singletons such as ST156 in pneumonia, and ST161 and ST396 in AOM. In contrast, eight STs were identified in meningitis, of which seven were genotypically closely related, while ST54 was the most frequent (62.9 %), unlike in the MLST database registrations, where ST6 predominated. CONCLUSION: Non-typeable H. influenzae (NTHi), mostly derived from pneumonia and AOM, were genetically diverse, in contrast to the predominance of H. influenzae type b (Hib) among meningitis cases. The associations between certain STs and β-lactam resistance among NTHi were confirmed.

© 2018, Centers for Disease Control and Prevention (CDC). All rights reserved. In Japan, Mycoplasma pneumoniae resistance to mac-rolides is high. To compare sequence types (STs) of susceptible and resistant isolates, we performed multilocus sequence typing for 417 isolates obtained in Japan during 2002–2016. The most prevalent ST overall was ST3, for macrolide-resistant was ST19, and for macrolide-suscepti-ble were ST14 and ST7.