Noriomi Ishibashi

Molecular epidemiology of carbapenem-non-susceptible Acinetobacter baumannii in Japan

OBJECTIVES Acinetobacter baumannii presents a clinical challenge when it is non-susceptible to carbapenems. The prevalence of carbapenem-non-susceptible A. baumannii in Japan is unclear, as previous studies have been limited in scope. We investigated the spread of carbapenem-non-susceptible A. baumannii in Japan and performed a comparison with findings from overseas. METHODS A total of 305 non-duplicate clinical isolates of Acinetobacter spp. from 176 medical facilities in all geographical regions of Japan were tested for susceptibility to antimicrobial agents by the agar dilution method. Isolates with MICs of imipenem ≥ 4 mg/L underwent PCR analysis of OXA-type β-lactamase gene clusters and metallo-β-lactamase genes. These isolates were further analysed by sequencing of OXA-type β-lactamases and by multilocus sequence typing (MLST). RESULTS Fifty-five of the 305 clinical isolates had MICs of imipenem ≥ 4 mg/L. The OXA-51-like carbapenemase gene was detected in 52 of these 55 isolates. Within the OXA-51-like gene cluster, OXA-66 was found in 43 (82.7%) of the 52 isolates. MLST identified the following sequence types (STs): ST74, ST76, ST92, ST106, ST188 and ST195 in 2 (3.8%), 2 (3.8%), 40 (76.9%), 5 (9.6%), 2 (3.8%) and 1 (1.9%) of the isolates, respectively. In particular, ST92 was found in 31 (91.2%) of the 34 A. baumannii isolates with MICs of imipenem ≥ 16 mg/L. CONCLUSIONS This is the first report on the molecular epidemiology of A. baumannii with MICs of imipenem ≥ 4 mg/L in Japan. OXA-66 and ST92 were dominant among these isolates.

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.

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.

Tuberculosis Exposure among Evacuees at a Shelter after Earthquake, Japan, 2011

Tuberculosis was diagnosed in a person who had stayed in a shelter after the 2011 Great East Japan Earthquake. A contact investigation showed that the prevalence of latent tuberculosis infection among other evacuees at the shelter was 20%. Our report underscores the importance of tuberculosis prevention and control after natural disasters.

IMP-1-producing carbapenem-resistant Acinetobacter ursingii from Japan

Sir, Acinetobacter baumannii represents the most clinically important and frequently detected Acinetobacter species. There has been concern about the possible emergence of carbapenem resistance in A. baumannii by acquisition of OXA-type carbapenemases or metallo-b-lactamases, since few effective antimicrobial agents are available. Several mechanisms could lead to carbapenem resistance in A. baumannii, including b-lactamases capable of hydrolysing carbapenems, loss of porins and up-regulation of efflux pumps. Currently, 33 genomic species have been identified by molecular methods in the genus Acinetobacter. A. baumannii is generally the most frequent pathogen among clinical isolates, although it is difficult to perform accurate species identification at many institutions. Recently, sequencing has provided reliable species identification of Acinetobacter isolates at some laboratories, and severe infections caused by species other than A. baumannii have been reported. Little is known about carbapenem resistance among non-A. baumannii species. With respect to Acinetobacter ursingii, there have been a few reports about bacteraemia due to this pathogen, but no mention of carbapenem resistance. We isolated carbapenem-resistant A. ursingii from a Japanese patient with a bloodstream infection. To our knowledge, this is the first reported clinical isolate of carbapenem-resistant A. ursingii. During the past 6 years (January 2005 to May 2011), we detected six A. ursingii isolates from blood cultures at our hospital, which has 1300 beds and is located in northern Japan. Of these six isolates, only one strain (isolated from the blood cultures of an inpatient) was carbapenem resistant. The patient was admitted to our hospital with rupture of an infected aortic aneurysm in 2010. He had several underlying diseases, including diabetes, hypertension and oropharyngeal carcinoma, and was on haemodialysis for chronic renal failure. Emergency aortic replacement was performed on the day of admission. Six days after surgery, carbapenem-resistant A. ursingii was isolated from a blood culture taken in the intensive care unit. Because of the antibiotic susceptibility profile, ciprofloxacin was administered intravenously. The patient had a central venous catheter, peripheral catheter, urethral catheter, thoracostomy tube and endotracheal tube. The patient continued to receive antibiotic therapy for 2 weeks, after which laboratory parameters normalized. Acinetobacter species were identified by the VITEK 2 bacterial identification system and genomic species identification was done by partial sequencing of the RNA polymerase b-subunit (rpoB) gene. MICs were determined by the agar dilution method of the CLSI. PCR was done to detect the OXA-51-like, OXA-23-like, OXA-24-like and OXA-58-like carbapenemase genes, as well as the IMP-1, IMP-2, VIM-1, VIM-2, SIM and NDM-1-type metallob-lactamase genes. Proximity of ISAba1, ISAba2, ISAba3 and IS18 to blaOXA-58-like genes 6 and the carO (outer membrane protein) gene was also investigated by PCR. In addition, the OXA-type carbapenemase and metallo-b-lactamase genes were sequenced. The MICs of the patient’s carbapenem-resistant A. ursingii isolate were as follows: piperacillin ≥256 mg/L; ceftazidime ≥256 mg/L; cefepime ≥256 mg/L; imipenem 32 mg/L; meropenem; 32 mg/L; levofloxacin 0.5 mg/L; and colistin 0.5 mg/L. PCR revealed that this isolate possessed both IMP-1 and OXA-58-like genes, with no other carbapenem resistance genes being detected. The OXA-58-like carbapenemase gene was not linked to ISAba1, ISAba2, ISAba3 or IS18. Sequencing of the blaOXA-58-like and blaIMP-1 genes yielded OXA-58 and IMP-1, respectively. The isolate also showed a loss of carO genes. Thus, the mechanism of resistance could have involved a synergistic interaction between IMP-1 expression and a loss of this outer membrane protein. Our findings are in accordance with a recent study from South Korea, where the blaIMP-1 gene was detected in several carbapenem-resistant non-A. baumannii isolates. Three Acinetobacter isolates with imipenem MICs ≥8 mg/L have been detected in blood cultures at our hospital over the past 6 years, and one of these isolates was identified as A. ursingii by partial rpoB gene sequencing. The remaining two isolates were identified as Acinetobacter soli. Use of molecular methods for identification of Acinetobacter genomic species has revealed the prevalence of various species. A recent study has shown that bacteraemia due to A. baumannii but also due to non-A. baumannii species may be associated with poor outcome. Our findings indicate that carbapenem resistance may exist among clinical isolates of A. ursingii and emphasize the importance of accurate epidemiological investigation of non-A. baumannii species, including A. ursingii.

The first case report of septic abortion resulting from β-lactamase-negative ampicillin-resistant non-typeable Haemophilus influenzae infection

Introduction. This is the first case report of septic abortion due to β-lactamase-negative ampicillin-resistant (BLNAR) non-typeable Haemophilus influenzae infection. In Japan, BLNAR H. influenzae is widespread and has become a clinical concern, especially in paediatrics and otolaryngology, but H. influenzae has not been previously recognized as a causative agent of obstetric or gynaecological infection. Case presentation. A 31-year-old pregnant woman presented at 17 weeks and 6 days of gestation with a high fever; she was admitted with a diagnosis of threatened premature delivery. Despite tocolytic treatment, she aborted spontaneously 2 h after admission and then entered septic shock. BLNAR H. influenzae was detected in both blood and vaginal cultures. Her condition gradually improved after several days of treatment with cefotaxime, and she was ultimately discharged without sequelae or complaints. Conclusion. Although penicillin with a β-lactamase inhibitor is currently recommended for the treatment of septic abortion, this combination will probably lead to treatment failure in the case of BLNAR H. influenzae infection. As this study reveals, H. influenzae can cause septic abortion; hence, future efforts should be undertaken to detect and therapeutically target this pathogen during pregnancy.