Positional advantages of supine MRI for diagnosis prior to breast­conserving surgery.

The present study aimed to evaluate the rate of positive surgical margins for magnetic resonance imaging (MRI) performed in the supine position prior to breast-conserving surgery (BCS). The rate of positive surgical margins and the clinicopathological factors were examined in consecutive patients with BCS who underwent preoperative MRI performed in the supine position at Sapporo Medical University Hospital (Sapporo, Japan) and related hospitals and clinics between January 2012 and December 2013. Of 1,175 eligible patients, 1,150 were included after excluding 25 patients with either bilateral breast cancer or stage IV disease. Positive margin was defined as no cancer seen on the resected margin. The primary endpoint was the rate of positive surgical margins when preoperative MRI was performed in the supine position and the secondary endpoint was identification of the factors that predict positive margins. Of the 1,150 female patients (median age, 55 years; range, 29-97 years) who underwent BCS for breast cancer following MRI performed in the supine position, 215 (18.8%) had positive margins, which is similar to the rate with MRI in the prone position, and 930 (81.2%) had negative margins. The rate of positive surgical margins in patients of the human epidermal growth factor receptor 2 (HER2) type was significantly higher than that in the non-HER2 type group (6.5 and 2.9%; χ2 P=0.0103). There was no increase in the rate of positive margins in breast cancers with a diameter of >T2. The rate of positive surgical margins following MRI performed in the supine position was 18.8%. Supine MRI appears to be suitable for informing on the extent of resection of breast cancer.

Decline in pediatric admission on an isolated island in the COVID-19 pandemic.

BACKGROUND: A decrease in pediatric hospitalizations during the COVID-19 pandemic has been reported worldwide; however, few studies have examined areas with a limited number of COVID-19 cases, where influenced by viral interference by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is minimum. METHODS: We conducted an epidemiological study of pediatric hospitalizations on Sado, an isolated island in Niigata, Japan, that was unique environment with few COVID-19 cases and reliable pediatric admissions monitoring. We compared numbers of monthly hospitalizations and associated diagnoses for the periods April 2016 to March 2020 (pre-pandemic period) and April 2020 to March 2021 (pandemic period). RESULTS: Data were analyzed for 1,144 and 128 patients in the pre-pandemic and pandemic periods, respectively. We observed only three adults and no pediatric COVID-19 cases during the pandemic period. The number of monthly admissions was significantly lower in the pandemic period (median [interquartile ranges (IQR)]: 11.0 [7.0-14.0]) than in the pre-pandemic period (23.0 [20.8-28.3]; P < 0.001). Similar decreases were observed for hospitalizations due to respiratory tract infection (P < 0.01), but not for asthma exacerbation (P = 0.15), and gastrointestinal tract infection (P = 0.33). CONCLUSIONS: Pediatric hospitalizations during the pandemic significantly decreased on an isolated Japanese island where COVID-19 was not endemic and all pediatric admissions were ascertainable. This observation highlights the impact of decreased travel and increased awareness of infection control measures on pediatric hospitalizations due to infectious diseases, not by the SARS-CoV-2 viral interference.

A follow-up study of a randomized controlled study evaluating safety and efficacy of leuprorelin acetate every-3-month depot for 2 versus 3 or more years with tamoxifen for 5 years as adjuvant treatment in premenopausal patients with endocrine-responsive breast cancer.

BACKGROUND: Previously, we conducted the 5-year open-label, randomized controlled trial (RCT) of leuprorelin adjuvant therapy in post-operative premenopausal patients with endocrine-responsive breast cancer, which was a pilot study to investigate the optimal duration of leuprorelin treatment. Since, however, long-term outcomes became required for the adjuvant endocrine therapy, we performed this follow-up observation study. METHODS: Follow-up observation study was performed up to 10th year after randomization, continuing RCT to evaluate the efficacy and safety of leuprorelin every 3 months for ≥ 3 versus 2 years, with daily tamoxifen for 5 years. Primary endpoints were disease-free survival (DFS) and 2-year landmark DFS. RESULTS: Eligible patients (N = 222) were randomly assigned to receive leuprorelin for either 2 years (N = 112) or ≥ 3 years (N = 110) with tamoxifen. Leuprorelin treatment for ≥ 3 years versus 2 years provided no significant difference in DFS (HR 0.944, 95% CI 0.486-1.8392) or 2-year landmark DFS (N = 99 and 102 in 2-year and ≥ 3-year groups, HR 0.834, 0.397-1.753). In small, higher-risk subgroup (n = 17); however, 2-year landmark DFS in ≥ 3-year group was significantly longer (HR 0.095, 0.011-0.850) than that in 2-year group. The incidence of bone-related adverse events was around 5% in both groups. CONCLUSIONS: Adjuvant leuprorelin treatment for ≥ 3 years with tamoxifen only showed similar efficacy and safety profiles to those for 2 years in analyses among all patients but suggested greater benefit in higher-risk patients. No new safety signal was identified for long-term leuprorelin treatment. TRIAL REGISTRATION NUMBER: Not applicable. This was an observational study.

A genome-wide association study identifies three novel genetic markers for response to tamoxifen: A prospective multicenter study.

PURPOSE: Although association studies of genetic variations with the clinical outcomes of breast cancer patients treated with tamoxifen have been reported, genetic factors which could determine individual response to tamoxifen are not fully clarified. We performed a genome-wide association study (GWAS) to identify novel genetic markers for response to tamoxifen. EXPERIMENTAL DESIGN: We prospectively collected 347 blood samples from patients with hormone receptor-positive and human epidermal growth factor receptor 2-negative, invasive breast cancer receiving preoperative tamoxifen monotherapy for 14 to 28 days. We used Ki-67 response in breast cancer tissues after preoperative short-term tamoxifen therapy as a surrogate marker for response to tamoxifen. We performed GWAS and genotype imputation using 275 patients, and an independent set of 72 patients was used for replication study. RESULTS: The combined result of GWAS and the replication study, and subsequent imputation analysis indicated possible association of three loci with Ki-67 response after tamoxifen therapy (rs17198973 on chromosome 4q34.3, rs4577773 on 6q12, and rs7087428 on 10p13, Pcombined = 5.69 x 10-6, 1.64 x 10-5, and 9.77 x 10-6, respectively). When patients were classified into three groups by the scoring system based on the genotypes of the three SNPs, patients with higher scores showed significantly higher after/before ratio of Ki-67 compared to those with lower scores (P = 1.8 x 10-12), suggesting the cumulative effect of the three SNPs. CONCLUSION: We identified three novel loci, which could be associated with clinical response to tamoxifen. These findings provide new insights into personalized hormonal therapy for the patients with breast cancer.

Significant Effect of Polymorphisms in CYP2D6 on Response to Tamoxifen Therapy for Breast Cancer: A Prospective Multicenter Study.

Purpose: CYP2D6 is the key enzyme responsible for the generation of the potent active metabolite of tamoxifen, "endoxifen." There are still controversial reports questioning the association between CYP2D6 genotype and tamoxifen efficacy. Hence, we performed a prospective multicenter study to evaluate the clinical effect of CYP2D6 genotype on tamoxifen therapy.Experimental Design: We enrolled 279 patients with hormone receptor-positive and human epidermal growth factor receptor 2-negative, invasive breast cancer receiving preoperative tamoxifen monotherapy for 14 to 28 days. Ki-67 response in breast cancer tissues after tamoxifen therapy was used as a surrogate marker for response to tamoxifen. We prospectively investigated the effects of allelic variants of CYP2D6 on Ki-67 response, pathological response, and hot flushes.Results: Ki-67 labeling index in breast cancer tissues significantly decreased after preoperative tamoxifen monotherapy (P = 0.0000000000000013). Moreover, proportion and Allred scores of estrogen receptor-positive cells in breast cancer tissues were significantly associated with Ki-67 response (P = 0.0076 and 0.0023, respectively). Although CYP2D6 variants were not associated with pathologic response nor hot flushes, they showed significant association with Ki-67 response after preoperative tamoxifen therapy (P = 0.018; between two groups, one with at least one wild-type allele and the other without a wild-type allele).Conclusions: This is the first prospective study evaluating the relationship between CYP2D6 variants and Ki-67 response after tamoxifen therapy. Our results suggest that genetic variation in CYP2D6 is a key predictor for the response to tamoxifen in patients with breast cancer. Clin Cancer Res; 23(8); 2019-26. ©2016 AACR.

Human parechovirus type 3 infection: Cause of apnea in infants born prematurely.

Four infants born prematurely presented with multiple apnea episodes caused by human parechovirus type 3 (HPeV3) infection. All patients required oxygen supplementation, and one patient required mechanical ventilation. HPeV3 infection might be included in the differential diagnosis of apnea in neonates and young infants, especially those born prematurely.

Prenatal vitamin A supplementation associated with adverse child behavior at 3 years in a prospective birth cohort in Japan.

BACKGROUND: Many pregnant women take vitamin supplements during pregnancy. The aim of this paper was to clarify the effects of dietary supplementation prior to and/or during pregnancy on child behavior. METHODS: A prospective birth cohort study from pregnancy to 3 years of age involving 1271 pairs of Japanese pregnant women and their newborns, was carried out. The women completed a self-administered questionnaire during the third trimester of pregnancy. To evaluate deviations in child behavior as an endpoint, each mother completed the Japanese Child Behavior Checklist for ages 2-3 years after 3 years of birth. Participant characteristics were compared between supplement takers and non-takers. RESULTS: Among many kinds of supplements, intake of supplemental vitamin A/ß-carotene prior to and/or during pregnancy was associated with hazardous effects on child behavior at 3 years of age (total t-score, P = 0.003; internal t-score, P = 0.027; external t-score, P = 0.013). This association held true even after adjusting for age, number of deliveries, infertility treatment, consumption of fast food, smoking status, maternal and paternal education, maternal and paternal income, gestational age at birth, anthropometry at birth (weight, height, head circumference and body circumference), and the State-Trait Anxiety Inventory at 3 years of age by means of multiple imputation. CONCLUSIONS: Intake of supplemental vitamin A prior to and/or during pregnancy may worsen child behavior at 3 years of age.

Influenza Virus Shedding in Laninamivir-Treated Children upon Returning to School.

The current School Health and Safety Act in Japan states that children with influenza infection should stay home until day 6(th) after symptoms onset. This was an amendment of a previous version recommending school return on day 3 after defervescence. Here, we investigated the duration of fever and virus shedding after laninamivir treatment in 7 children infected with influenza A(H3N2) virus and 21 children with influenza B virus in relation to the school return timing recommended by the School Health and Safety Act during the 2011-2012 influenza season. Nasal discharge was collected on the first, second, and third hospital visits and virus titers were assessed by virus culture and real-time PCR. Duration of fever after laninamivir treatment was 1 day longer for influenza B than for influenza A(H3N2). Virus detection rates with 50% tissue culture infectious dose and viral RNA were highest at the first visit and gradually decreased at subsequent visits. Virus positivity rates were detectable at the time of defervescence in less than half of the enrolled patients (14.3-42.9%). Virus shedding rates were similarly low (0.0-19.0%) on day 3 or later from defervescence and on day 6 or later from fever onset (school return dates per the old and current School Health and Safety Act) regardless of the influenza type. In conclusion, despite the higher efficacy of laninamivir against A(H3N2) viruses than B viruses, viral shedding is low after return to school for both types, regardless of the version of the School Health and Safety Act.

A phase I study of combination therapy with nanoparticle albumin-bound paclitaxel and cyclophosphamide in patients with metastatic or recurrent breast cancer.

BACKGROUND: The objective of the present clinical study is to determine the maximum tolerated dose (MTD)/recommended dose (RD) of combination therapy with nanoparticle albumin-bound paclitaxel (nab-PTX) and cyclophosphamide (CPA) in patients with metastatic or recurrent breast cancer. METHODS: nab-PTX and CPA were administered on the first day of each 21-day treatment cycle. The dose of CPA was fixed at 600 mg/m(2), while the dose of nab-PTX was increased from 180 mg/m(2) (Level 1) to 220 mg/m(2) (Level 2) and then to 260 mg/m(2) (Level 3). RESULTS: A total of 11 patients from two institutions were enrolled in the present study. At Level 3, a dose-limiting toxicity (DLT) was observed in 1 patient. Considering treatment continuity and the risk of adverse events in Cycle 2 and thereafter at this level, further subject enrollment at Level 3 was discontinued after two patients had been enrolled. Since the doses used at Level 3 were considered the MTD of nab-PTX and CPA and the doses used at Level 2 were considered the RD of nab-PTX and CPA, three additional subjects were enrolled at Level 2. No DLTs were observed at Level 2. CONCLUSION: The RD of combination therapy with nab-PTX and CPA was 220 mg/m(2) and 600 mg/m(2), respectively, in patients with metastatic or recurrent breast cancer.

Molecular epidemiology and serogroup 6 capsular gene evolution of pneumococcal carriage in a Japanese birth cohort study.

Antibiotic resistance in Streptococcus pneumoniae is a major concern worldwide. However, it is unclear whether resistance is associated with only a few highly prevalent clones or numerous and diverse clones. We monitored 349 healthy children and obtained nasopharyngeal cultures at five time points coinciding with health check-ups (4, 7, 10, 18 and 36 months) between 2008 and 2012. A total of 497 S. pneumoniae isolates from 257 healthy children were characterized using capsular serotyping, multilocus sequence typing and antibiotic resistance genotyping (ermB, mefA/E and pbp mutations). Among these isolates, 25 serotypes and 66 sequence types (STs) were found, including 24 new STs with 11 new alleles. Although resistance was present in a variety of ST clones, most of the clones (57/66, 86.4 %) had one specific resistant or susceptible genotype. Of 233 phenotypically penicillin-non-susceptible isolates, 196 (84.1 %) belonged to only six clones, comprising ST90(6B), ST236(19F), ST242(23F), ST3787(6A), ST1437(23F) and ST338(23A) and their variants. We concluded that drug-resistant S. pneumoniae is associated with a limited number of highly prevalent clones that are capable of adapting to the community setting. Furthermore, we analysed the capsular gene evolution in serogroup 6. The strain ST2924(6D) was probably the result of recombination of a 3563 bp fragment of the capsule locus acquired by an ST2924(6C) strain from an ST90(6B) or ST2924(6B) strain. Compared with previous studies, our results showed a different recombination site (wciN and wzx) and a different cps profile (8-7-11), indicating that serogroup 6 strains have multiple sites for cps recombination as a mechanism of vaccine escape.

[Two cases of multiple liver metastases breast cancer successfully treated with combination chemotherapy by S-1, vinorelbine and medroxyprogesterone].

We report our experience with two cases of postoperative multiple liver metastases that were reduced remarkably by S-1, VNR, and MPA combination therapy for breast cancer. A case diagnosed as Stage II B(T2, N1, M0)breast cancer was treated postoperatively with LH-RH agonist and TAM. Another case, diagnosed as Stage III B(T4b, N2, M0), was treated with postoperative CE therapy. Tumor markers were normalized and liver metastases were shrunk significantly in both cases which received combination chemotherapy of S-1, VNR, and MPA as first-line therapy after recurrence. We conclude that this combination chemotherapy is a useful regimen for metastatic breast cancer patients, because it can be continuously implemented over a long period of time while maintaining high QOL without serious adverse events.

Incidence survey of acute otitis media in children in Sado Island, Japan--Sado Otitis Media Study (SADOMS).

BACKGROUND: Acute otitis media (AOM) is one of the most common forms of bacterial infection and cause for clinic visits in children. The incidence of AOM was 0.9-1.2 episodes per person-year during the first 2 years of life in previous reports conducted before 2000. The aim of this study was to 1) evaluate the latest AOM incidence in pediatric outpatients and 2) identify the bacterial pathogens from these patients and ascertain their serotypes and resistance. METHODS: The study was conducted in a closed population, involving all pediatricians and otolaryngologists in Sado Island allowing accurate determination of AOM incidence. In each month, one week was assigned as "surveillance week", and all outpatients with acute illness aged 0-18 years examined during the surveillance weeks were enrolled. AOM was diagnosed on the basis of otoscopic findings and clinical symptoms were recorded. Specimens were collected from the nasopharynx or middle ear cavity of AOM patients and examined for bacteria. Antimicrobial susceptibilities, serotypes, and molecular typing for resistance were determined among Streptococcus pneumoniae and Haemophilus influenzae. RESULTS: In total, 8,283 clinic visits were conducted, and 354 episodes (4.3%, 95% CI: 3.9-4.7%) among 312 children were diagnosed as AOM. The incidence of AOM was highest in children of 1 year of age (0.54 episodes/child/year, 95% CI: 0.44-0.64). Serotype coverage of 7- and 13-valent pneumococcal conjugate vaccines in this study were 38.0% (95% CI: 29.3-47.3) and 62.8% (95% CI: 53.6-71.4), respectively. Of 122 H.influenzae isolates available for typing, 120 were nontypeable and 2 were type b. A high proportion of S. pneumoniae isolates (46%) showed resistance to penicillin. Approximately half of H. influenzae isolates had genetic markers for beta-lactamase-negative ampicillin-resistance. CONCLUSIONS: Approximately 4-5% of pediatric outpatients, even without AOM-related symptoms, had AOM in our study. Pediatricians as well as otolaryngologists should check the tympanic membrane findings of all pediatric outpatients.

Individual risk factors associated with nasopharyngeal colonization with Streptococcus pneumoniae and Haemophilus influenzae: a Japanese birth cohort study.

BACKGROUND: The first step in a bacterial disease is the establishment of nasopharyngeal carriage. METHODS: We conducted a birth cohort study to identify factors associated with colonization in healthy children and evaluate the serotype distributions and resistances of Streptococcus pneumoniae/Haemophilus influenzae. Nasopharyngeal cultures were obtained from 349 subjects at 5 time points coinciding with health checkups (4, 7, 10, 18 and 36 months). RESULTS: A total of 551 S. pneumoniae (penicillin resistance rate: 46.3%) and 301 H. influenzae (ampicillin resistance rate: 44.5%) isolates were obtained from 1654 samples. In this study, 47.5% and 60.9% of S. pneumoniae isolates were included in the serotypes of 7- and 13-valent pneumococcal conjugate vaccines, respectively. Analyzing by Cox proportional hazards models, cohabiting older sibling(s) attending day-care (hazard ratios: 2.064-3.518, P < 0.001) and an early start of day-care attendance by the subjects themselves (2.259-2.439, P < 0.001) were associated with a higher risk of early colonization regardless of their susceptibility. Recent exposure to antimicrobials was also significantly associated with increased risk of colonization (odds ratios: 2.032-2.999, P < 0.001) but not with resistance rates. This data indicated that introduction of appropriate antimicrobial usage in areas of overuse of antimicrobials could contribute to lower colonization of S. pneumoniae/H. influenzae, resulting in a decrease in the absolute number of resistant isolates. CONCLUSIONS: Strategies to control transmission at day-care centers or from older sibling(s) as well as appropriate use of antimicrobials are essential for reducing colonization and the absolute number of resistant isolates.

Molecular epidemiology of methicillin-resistant Staphylococcus aureus isolated from children in a community with low antimicrobial pressure in Japan.

Sado Island in Japan is an area with low antimicrobial pressure. A total of 41 community-onset methicillin-resistant Staphylococcus aureus (MRSA) isolates were obtained from pediatric outpatients and healthy children between August 2009 and January 2012, and genotyping and antimicrobial susceptibility testing of the MRSA isolates were performed. Additionally, the sources of MRSA isolated from healthy 1-month-old neonates were assessed. All isolates were negative for the Panton-Valentine leukocidin genes. Our data showed a lower prevalence of staphylococcal cassette chromosome (SCC)mecII on Sado Island (31.7% in total and 46.7% in healthy carriage) than that in the other areas of Japan, suggesting that a low level of antimicrobial use may be related to a low SCCmecII carriage rate in the community. To our knowledge, this is the first report of sequence type (ST)81/SCCmecIVg strains as well as the novel ST strain (ST2180/SCCmecIVa) in Japan. In addition, we detected an arginine catabolic mobile element (ACME)-arcA-positive ST764/SCCmecIIa clone that could disseminate successfully in the community. Intrafamilial transmission was observed in neonates identified with the SCCmecIV MRSA strains, and these strains were genetically typed as community-associated MRSA; the transmission routes of the remaining SCCmecIIa MRSA (genetically typed as healthcare-associated MRSA) strains could not be defined. In this study, we have shown that multiple MRSA strains can circulate in a community even under low antimicrobial pressure.

A genome-wide association study identifies a genetic variant in the SIAH2 locus associated with hormonal receptor-positive breast cancer in Japanese.

In Japan, breast cancer is the most common cancer among women and the second leading cause of cancer death among women worldwide. To identify genetic variants associated with the disease susceptibility, we performed a genome-wide association study (GWAS) using a total of 1086 Japanese female patients with hormonal receptor-positive (HRP) breast cancer and 1816 female controls. We selected 33 single-nucleotide polymorphisms (SNPs) with suggestive associations in GWAS (P-value of <1 × 10(-4)) as well as 4 SNPs that were previously implicated their association with breast cancer for further replication by an independent set of 1653 cases and 2797 controls. We identified significant association of the disease with a SNP rs6788895 (P(combined) of 9.43 × 10(-8) with odds ratio (OR) of 1.22) in the SIAH2 (intron of seven in absentia homolog 2) gene on chromosome 3q25.1 where the involvement in estrogen-dependent diseases was suggested. In addition, rs3750817 in intron 2 of the fibroblast growth factor receptor 2 gene, which was reported to be associated with breast cancer susceptibility, was significantly replicated with P(combined) of 8.47 × 10(-8) with OR=1.22. Our results suggest a novel susceptibility locus on chromosome 3q25.1 for a HRP breast cancer.

[Colonization and transmission of Haemophilus influenzae type b (Hib)].

Haemophilus influenzae type b (Hib) remains the leading cause of invasive bacterial infection in Japanese children. More than 110 countries that have included Hib conjugate vaccines in their routine vaccination programs have seen dramatical decrease in the incidence of Hib infections. In Japan, the vaccine has been introduced for voluntary immunization since December 2008 and has been provided free of charge only since January 2011. This review reports the prevalence of Hib and its clones among healthy children and pediatric patients diagnosed with invasive or non-invasive Hib infections in Sado Island, Japan. Of 25 Hib isolates collected in this surveillance, 4 genotypic patterns (ST54-gBLPACR-III, ST54-gBLNAR-I/II, ST190-gBLNAS, and ST95-gBLPACR-I/II) were detected. These STs were double or triple-locus variants of each other. Under the same antimicrobial selective pressure, high prevalence of gBLPACR strain (76.0%) was confirmed in Hib isolates, while gBLPACR prevalence in nontypeable H. influenzae was very low (5.2%). These data suggested that each ST strain may be brought into Sado Island by different routes. We note that surveillance of healthy subjects to identify Hib carriers is important to understand their role in transmission of Hib.

A genome-wide association study identifies locus at 10q22 associated with clinical outcomes of adjuvant tamoxifen therapy for breast cancer patients in Japanese.

Although many association studies of polymorphisms in candidate genes with the clinical outcomes of breast cancer patients receiving adjuvant tamoxifen therapy have been reported, genetic factors determining individual response to tamoxifen are not fully understood. To identify genetic polymorphisms associated with clinical outcomes of patients with tamoxifen treatment, we conducted a genome-wide association study (GWAS). We studied 462 Japanese patients with hormone receptor-positive, invasive breast cancer receiving adjuvant tamoxifen therapy. Of them, 240 patients were analyzed by genome-wide genotyping using the Illumina Human610-Quad BeadChips, and two independent sets of 105 and 117 cases were used for replication studies. In the GWAS, we detected significant associations with recurrence-free survival at 15 single-nucleotide polymorphisms (SNPs) on nine chromosomal loci (1p31, 1q41, 5q33, 7p11, 10q22, 12q13, 13q22, 18q12 and 19p13) that satisfied a genome-wide significant threshold (log-rank P= 2.87 × 10(-9)-9.41 × 10(-8)). Among them, rs10509373 in C10orf11 gene on 10q22 was significantly associated with recurrence-free survival in the replication study (log-rank P= 2.02 × 10(-4)) and a combined analysis indicated a strong association of this SNP with recurrence-free survival in breast cancer patients treated with tamoxifen (log-rank P= 1.26 × 10(-10)). Hazard ratio per C allele of rs10509373 was 4.51 [95% confidence interval (CI), 2.72-7.51; P= 6.29 × 10(-9)]. In a combined analysis of rs10509373 genotype with previously identified genetic makers, CYP2D6 and ABCC2, the number of risk alleles of these three genes had cumulative effects on recurrence-free survival among 345 patients receiving tamoxifen monotherapy (log-rank P= 2.28 × 10(-12)). In conclusion, we identified a novel locus associated with recurrence-free survival in Japanese breast cancer patients receiving adjuvant tamoxifen therapy.

Genotyping of Haemophilus influenzae type b in pre-vaccination era.

Identification of Haemophilus influenzae type b (Hib) in asymptomatic carriers is critical to control the spread of disease. This study was conducted between January 2008 and August 2011 as part of a birth cohort study in Sado Island, Japan, to elucidate the prevalence of Hib and its clones in a specific region. Nasopharyngeal cultures were obtained from 349 subjects at 4-, 7-, 10-, 18-, and 36-month health checkups and analyzed for H. influenzae. The Hib and nontypeable H. influenzae detection rates ranged from 0 to 1.5% (12 isolates) and from 7.9 to 32.9%, respectively. Twelve pediatric patients diagnosed with invasive or non-invasive Hib infections during the study period were also enrolled. The Hib isolates were analyzed for carriage of the beta-lactamase gene and ftsI mutations, and multilocus sequence type (MLST, ST type). Of the 24 Hib isolates, 18 (75%) were ST54, 5 (21%) were ST190, and 1 isolate (4%) was ST95. All of the ST190 isolates were genetically beta-lactamase-negative ampicillin-susceptible isolates, while all but one of the ST54 isolates were genetically beta-lactamase-positive amoxicillin/clavulanic acid-resistant isolates. The geographic distribution of Hib isolates in the study period was scattered. There were 2 day-care cases and 1 family case of Hib infection. The ST54 and ST190 strains circulated in Sado Island and were detected in both asymptomatic carriers and patients. We note that surveillance of healthy subjects to identify Hib carriers is important to understand the transmission of Hib.