Shinya Inomata

Molecular Characteristics of Extended-Spectrum β-Lactamases in Clinical Isolates from Escherichia coli at a Japanese Tertiary Hospital

The prevalence of ESBL has been increasing worldwide. In this study, we investigated the molecular characteristics of ESBL among clinical isolates of Escherichia coli from a Japanese tertiary hospital. A total of 71 consecutive and nonduplicate clinical isolates of ESBL-positive E. coli collected at Tohoku University Hospital between January 2008 and March 2011 were studied. The antimicrobial susceptibility profile of these strains was determined. PCR and sequencing were performed to identify genes for β-lactamase (bla TEM, bla SHV, bla OXA-1-like, and bla CTX-M) and plasmid-mediated quinolone resistance determinants (PMQR). The isolates were also analyzed by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). Of the 71 strains, 68 were positive for CTX-M, 28 were positive for TEM, four were positive for OXA-1, and one was positive for SHV. Sequencing revealed that CTX-M-14 was the most prevalent (31/71), followed by CTX-M-27 (21/71) and then CTX-M-15 (9/71). Of the 28 TEM-positive strains, one was TEM-10 and the rest were TEM-1. One SHV-positive strain was SHV-12. The 21 CTX-M-27-producing isolates were divided into 14 unique PFGE types, while the 9 CTX-M-15 producers were divided into 8 types. Based on MLST, 9 CTX-M-14 procedures, 19 CTX-M-27 procedures, and 8 CTX-M-15 producers belonged to ST131. Thirty-five (94.6%) of the 37 ST131 E. coli strains showed resistance to levofloxacin, which was a higher rate than among non-ST131 strains (63.6%). Among ESBL-producing isolates, one, two, and six possessed qnrB, qnrS, qepA, and aac(6′)-Ib-cr, respectively. Of the 6 isolates with aac(6′)-Ib-cr, 4 carried the CTX-M-15 gene. Our data suggest that CTX-M-15-producing E. coli ST131 has emerged as a worldwide pandemic clone, while CTX-M-27 (a variant of CTX-M-14) is also spreading among E. coli ST131 in Japan.

Characteristics of infectious diseases in hospitalized patients during the early phase after the 2011 great East Japan earthquake: pneumonia as a significant reason for hospital care.

BACKGROUND Natural catastrophes increase infectious disease morbidity rates. On March 11, 2011, a 9.0-magnitude earthquake and associated Pacific coast tsunami struck East Japan. The aim of this study was to investigate the characteristics of patients with infectious diseases who needed hospitalization after this disaster. METHODS We searched the medical records of 1,577 patients admitted to Tohoku University Hospital in the Sendai area within 1 month (March 11, 2011-April 11, 2011) after the disaster. We examined (1) changes in the rates of hospitalizations for infectious diseases over time and (2) the variety of infectious diseases. RESULTS The number of hospitalized patients with infectious diseases increased after the fi rst week to double that during the same period in 2010. Pneumonia comprised 43% of cases, and 12% consisted of skin and subcutaneous tissue infection, including tetanus. Pneumonia was prevalent in elderly patients (median age, 78 years) with low levels of serum albumin and comorbid conditions, including brain and nervous system disorders. Sputum cultures contained Streptococcus pneumoniae, Moraxella catarrhalis, and Haemophilus influenzae , known pathogens of community-acquired pneumonia in Japan. In addition, 20.5% of patients had positive results for urinary pneumococcal antigen. CONCLUSIONS Among hospitalized patients, infectious diseases were significantly increased after the disaster compared with the same period in 2010, with pneumonia being prominent. The analyses suggest that taking appropriate measures for infectious diseases, including pneumonia, may be useful for disaster preparedness and medical response in the future.

High frequency of IMP-6 among clinical isolates of metallo-β-lactamase-producing Escherichia coli in Japan

Carbapenems are the most potent agents for treating infections by Gram-negative bacteria due to their stability with respect to the majority of β-lactamases and their high rate of penetration through the bacterial outer membranes. However, there have been increasing reports of Gram-negative

Post-Tsunami Outbreaks of Influenza in Evacuation Centers in Miyagi Prefecture, Japan

We describe 2 post-tsunami outbreaks of influenza A in evacuation centers in Miyagi Prefecture, Japan, in 2011. Although containment of the outbreak was challenging in the evacuation settings, prompt implementation of a systemic approach with a bundle of control measures was important to control the influenza outbreaks.

Impact of the Seven-valent Pneumococcal Conjugate Vaccine on Acute Otitis Media in Japanese Children: Emergence of Serotype 15A Multidrug-resistant Streptococcus pneumoniae in Middle Ear Fluid Isolates.

Background: Streptococcus pneumoniae is one of the most common bacteria causing acute otitis media (AOM). In Japan, a 7-valent pneumococcal conjugate vaccine (PCV7) was introduced for voluntary vaccination of children in 2010, and it became a recommended vaccination in April 2013. We surveyed the serotypes and antimicrobial susceptibility profile of S. pneumoniae isolates obtained from the middle ear fluid of Japanese children with AOM. Methods: Between April and September 2013, a total of 176 S. pneumoniae isolates were obtained from the middle ear fluid of children aged 0–3 years with AOM. Isolates were collected from various regions of Japan. Minimum inhibitory concentrations were measured by the broth microdilution method. Serotyping was performed by observing the Quellung reaction. Results: Although 45.5% of the strains were susceptible to penicillin G, 42.6% were penicillin-intermediate strains and 11.9% were penicillin-resistant strains. Serotype 19A (27.3%), serotype 15A (14.2%) and serotype 3 (11.9%) showed a high frequency. Although PCV7 types only accounted for 4.5% of all strains, 44.9% were PCV13 types and 55.1% were non-PCV types. Serotype 15A strains were 100% nonsusceptible to penicillin G and all of these strains showed multidrug resistance. Serotype 15A was frequent in children up to 1 year old. Conclusion: After this research was completed, PCV7 was switched to a PCV13 that also contained serotype 3 and serotype 19A. We need to consider the possibility that serotype 15A, which is not included in PCV13, may increase and cause intractable AOM in the future.

Microbiological and molecular epidemiological analyses of community-associated methicillin-resistant Staphylococcus aureus at a tertiary care hospital in Japan.

Molecular characterization of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) is generally conducted referred to staphylococcal cassette chromosome mec (SCCmec) type IV or V. CA-MRSA is now a cause of concern since such strains have been isolated not only from individuals in a community but also from patients in healthcare settings. The aim of this study was to analyze microbiological and molecular epidemiological features of CA-MRSA strains at a Japanese tertiary care hospital using PCR based-open reading frame typing (POT). This technique allows for molecular classification into CA-MRSA (POT-CA) and hospital-associated (HA-) MRSA (POT-HA) with clonal discrimination. Clinical MRSA isolates obtained from consecutive patients between October 1, 2012 and September 30, 2013 at the hospital were analyzed in combination with the clinical definition for CA-MRSA by the Centers for Disease Control and Prevention and POT. Of 219 isolates (76 clonal groups), 64 (29.3%) were clinical-HA/POT-CA isolates (22 clonal groups). Some clones of them accumulated in this hospital and might be involved in nosocomial transmission. Virulent factors of the isolates were analyzed, and only one (1.6%) Panton-Valentine leukocidin gene positive isolate but no arginine catabolic mobile element genes positive isolate were found in clinical-HA/POT-CA. Additionally, clinical-HA/POT-CA isolates showed higher antimicrobial susceptibility than clinical-HA/POT-HA, especially to minocycline, doxycycline, and amikacin. The most frequent genotype of molecular CA-MRSA was multi-locus sequence type 5-SCCmecIV, previously not detected in Japan. Although CA-MRSA at this hospital showed low virulence and higher antimicrobial susceptibility, the risk of nosocomial infection from them should be recognized, requiring stricter infection control measures.

High Frequency of Acinetobacter soli among Acinetobacter Isolates Causing Bacteremia at a Tertiary Hospital in Japan

ABSTRACT Acinetobacter baumannii is generally the most frequently isolated Acinetobacter species. Sequence analysis techniques allow reliable identification of Acinetobacter isolates at the species level. Forty-eight clinical isolates of Acinetobacter spp. were obtained from blood cultures at Tohoku University Hospital. These isolates were identified at the species level by partial sequencing of the RNA polymerase β-subunit (rpoB), 16S rRNA, and gyrB genes. Then further characterization was done by using the PCR for detection of OXA-type β-lactamase gene clusters, metallo-β-lactamases, and carO genes. Pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing were also performed. The most frequent isolate was Acinetobacter soli (27.1%). Six of the 13 A. soli isolates were carbapenem nonsusceptible, and all of these isolates produced IMP-1. PFGE revealed that the 13 A. soli isolates were divided into 8 clusters. This study demonstrated that A. soli accounted for a high proportion of Acinetobacter isolates causing bacteremia at a Japanese tertiary hospital. Non-A. baumannii species were identified more frequently than A. baumannii and carbapenem-nonsusceptible isolates were found among the non-A. baumannii strains. These results emphasize the importance of performing epidemiological investigations of Acinetobacter species.

Impact of psm-mec in the mobile genetic element on the clinical characteristics and outcome of SCCmec-II methicillin-resistant Staphylococcus aureus bacteraemia in Japan.

Over-expression of alpha-phenol-soluble modulins (PSMs) results in high virulence of community-associated methicillin-resistant Staphylococcus aureus (MRSA). The psm-mec gene, located in the mobile genetic element SCCmec-II, suppresses PSMαs production. Fifty-two patients with MRSA bacteraemia were enrolled. MRSA isolates were evaluated with regard to the psm-mec gene sequence, bacterial virulence, and the minimum inhibitory concentration (MIC) of vancomycin and teicoplanin. Fifty-one MRSA isolates were classified as SCCmec-II, and 10 had one point mutation in the psm-mec promoter. We compared clinical characteristics and outcomes between mutant MRSA and wild-type MRSA. Production of PSMα3 in mutant MRSA was significantly increased, but biofilm formation was suppressed. Wild-type MRSA caused more catheter-related bloodstream infections (30/41 vs. 3/10, p 0.0028), whereas mutant MRSA formed more deep abscesses (4/10 vs. 3/41, p 0.035). Bacteraemia caused by mutant MRSA was associated with reduced 30-day mortality (1/10 vs. 13/41, p 0.25), although this difference was not significant. The MIC90 of teicoplanin was higher for wild-type MRSA (1.5 mg/L vs. 1 mg/L), but the MIC of vancomycin was not different between the two groups. The 30-day mortality of MRSA with a high MIC of teicoplanin (≥1.5 mg/L) was higher than that of strains with a lower MIC (≤0.75 mg/L) (6/10 vs. 6/33, p 0.017). Mutation of the psm-mec promoter contributes to virulence of SCCmec-II MRSA, and the product of psm-mec may determine the clinical characteristics of bacteraemia caused by SCCmec-II MRSA, but it does not affect mortality.

Molecular Epidemiology of Ampicillin-resistant Haemophilus influenzae Causing Acute Otitis Media in Japanese Infants and Young Children.

Background: Nontypeable Haemophilus influenzae is a particularly important cause of acute otitis media (AOM). There is a high prevalence of &bgr;-lactamase–nonproducing ampicillin-resistant (BLNAR) strains in Japanese children, which is associated with recurrent AOM and prolonged treatment. The aim of this study was to investigate the antimicrobial susceptibility profile, mechanisms of ampicillin resistance and molecular epidemiology of ampicillin resistance in H. influenzae strains causing AOM in Japanese children. Methods: One hundred fifty-seven strains of H. influenzae isolated from the middle ear fluid of pediatric patients (aged 0–3 years) with AOM from various areas of Japan were studied. The antimicrobial susceptibility profile, genes encoding &bgr;-lactamase and alterations of penicillin-binding protein 3 were investigated. Genetic relatedness among ampicillin-resistant isolates was examined by multilocus sequence typing and pulsed-field gel electrophoresis. Results: Of 157 isolates, 108 (68.8%) demonstrated reduced susceptibility to ampicillin, including 95 (60.5%) of &bgr;-lactamase–nonproducing isolates and 13 (8.3%) of &bgr;-lactamase–producing isolates. All BLNAR (minimum inhibitory concentration of ampicillin ≥ 4 mg/L) isolates had amino acid substitutions related to ampicillin resistance. Multilocus sequence typing and pulsed-field gel electrophoresis demonstrated genetic diversity although there were 2 clusters of highly resistant isolates with identical STs (sequence types; ST161 and 549). Conclusions: Alterations of penicillin-binding protein 3 represented the most prevalent mechanism of ampicillin resistance among H. influenzae isolates causing AOM in Japanese children. BLNAR isolates from children with AOM demonstrated genetic diversity. This study identified for the first time ST clones associated with BLNAR H. influenzae causing AOM in Japanese children.

A survey conducted immediately after the 2011 Great East Japan Earthquake: Evaluation of infectious risks associated with sanitary conditions in evacuation centers

In cooperation with the Miyagi prefectural government, we conducted a survey of the management of sanitation at evacuation centers and the health of the evacuees by visiting 324 evacuation centers at two weeks after the 2011 Great East Japan Earthquake. The facilities often used as evacuation centers were community centers (36%), schools (32.7%) and Nursing homes (10.2%). It was more difficult to maintain a distance of at least 1 m between evacuees at the evacuation centers with a larger number of residents. At evacuation centers where the water supply was not restored, hygienic handling of food and the hand hygiene of the cooks were less than adequate. Among evacuation centers with ≤50 evacuees, there was a significant difference in the prevalence rate of digestive symptoms between the centers with and without persons in charge of health matters (0.3% vs. 2.1%, respectively, p < 0.001). The following three factors had an important influence on the level of sanitation at evacuation centers and the health of evacuees: 1) the size of the evacuation center, 2) the status of the water supply, and 3) the allocation of persons in charge of health matters. Given that adjusting the number of evacuees to fit the size of the evacuation center and prompt restoration of the water supply are difficult to achieve immediately after an earthquake, promptly placing persons in charge of health matters at evacuation centers is a practicable and effective measure, and allocation of at least one such person per 50 evacuees is desirable.