Mitsutaka Iguchi

Molecular and clinical characterization of plasmid-mediated AmpC β-lactamase-producing Escherichia coli bacteraemia: a comparison with extended-spectrum β-lactamase-producing and non-resistant E. coli bacteraemia

Plasmid-mediated AmpC β-lactamase-producing Escherichia coli (AmpC-E) bacteraemia was characterized by comparison with bacteraemia caused by extended-spectrum β-lactamase (ESBL)-producing E. coli (ESBL-E) and non-resistant E. coli (NR-E) in the era of the worldwide spread of the CTX-M-15-producing O25b-ST131-B2 clone. Of 706 bloodstream E. coli isolates collected between 2005 and 2010 in three Japanese university hospitals, 111 ESBL screening-positive isolates were analysed for AmpC and ESBL genes by PCR. A case-control study was performed in which the cases consisted of all of the patients with AmpC-E bacteraemia. Phylogenetic groups, sequence types and O25b serotype were determined. Twenty-seven AmpC-E isolates (26 of which were of the CMY-2 type) were identified, and 54 ESBL-E and 54 NR-E isolates were selected for the controls. Nineteen AmpC-E isolates were also positive for ESBL. CTX-M-14 was the most prevalent ESBL type among both the AmpC-E and ESBL-E isolates. The O25b-ST131-B2 clone was the most prevalent among the ESBL-E isolates (26%) and the second most prevalent among the NR-E isolates (13%), but only one O25b-ST131-B2 clone was found among the AmpC-E isolates. Twenty-three different sequence types were identified among the AmpC-E isolates. When compared with bacteraemia with ESBL-E, previous isolation of multidrug-resistant bacteria and intravascular catheterization were independently associated with a lower risk for AmpC-E. When compared with NR-E bacteraemia, prior use of antibiotics was the only significant risk factor for AmpC-E. Unlike the spread of the O25b-ST131-B2 clone between ESBL-E and NR-E, the AmpC-E isolates were not dominated by any specific clone.

The first point prevalence survey of health care–associated infection and antimicrobial use in a Japanese university hospital: A pilot study

BACKGROUND Point prevalence surveys (PPSs) in Japanese hospitals have not yet been reported. The purpose of this pilot PPS study was to evaluate the epidemiology of health care-associated infections (HAIs) and antimicrobial use in a Japanese tertiary university hospital. METHODS A 1-day, cross-sectional PPS was performed at a Japanese university hospital. Data on demographics, active HAIs, and antimicrobial use of all inpatients were collected using a data collection form. RESULTS Of 841 patients, 85 (10.1%) had 90 active HAIs, and 308 patients (36.6%) were administered 494 antimicrobials. Among the 90 HAIs and 58 pathogens, the most frequent infection and isolated pathogen were pneumonia (20.0%) and Enterobacteriaceae (27.6%), respectively. Of the 118 antimicrobials used for treatment of HAIs, carbapenems were the most frequently administered category of antimicrobials (22.9%). In regard to antimicrobials for surgical prophylaxis, 37 of 119 (31.1%) were administered to patients on postoperative day 3 or later, and 48 of 119 (40.3%) were administered orally. CONCLUSIONS The incidence of HAIs is higher than in other developed countries. The social and medical situation in Japan may affect patient demographics, active HAIs, and antimicrobial use. Multicenter PPSs are necessary to uncover the real epidemiology of HAIs and antimicrobial use in Japan.

Cryptococcal Cellulitis in a Patient with Bullous Pemphigoid

Cryptococcosis is a rare, life-threatening fungal infection caused by the yeast-like encapsulated fungus Cryptococcus neoformans. It is considered an opportu-nistic infection as it affects mainly immunosuppressed individuals (1, 2). The disease is believed to be acquired mainly by inhalation of the infectious propagule from the environment. In humans, C. neoformans causes various kinds of clinical manifestations; meningoencephalitis, pneumonia, skin lesions, eye lesions, bone involvement, etc. (3). AIDS is the predisposing factor in approximately 90% of cryptococcal infections (4). Other defects in T-cell-mediated immunity are also predisposing factors of infection, such as haematological malignancies (4). We report here an elderly male patient with bullous pemphigoid (BP) who was complicated with cryptococ-cal cellulites. A 79-year-old man, living in a big city in Japan, presented with swelling, erythema and severe pain of the left arm. The skin lesions had developed rapidly. The patient reported an accidental injury of the left arm before the skin lesions. The patient had had BP for one year and had been treated with oral prednisolone at 17.5 mg daily from the onset of the lesion on the arm. The diagnosis of BP was based on skin manifestations of generalized multiple bullae (Fig. 1), histological features of subepidermal blisters with eosinophilic infiltration, deposition of IgG and C3 at the dermal basement membrane zone, and high-titre circulating anti-BP180 antibodies detected with BP180 enzyme-linked im-munoassay (ELISA) (MBL Intl. Corp., Nagoya, Japan). On examination, the left forearm exhibited swelling and ery-thema, suggesting cellulitis. The left axillary lymph nodes were palpable. The results of blood examination were as follows: white blood cell count of 11,600/µl (normal: 4,000–8,000/µl), C-reactive protein of 6.77 mg/dl (< 0.30 mg/dl), urea nitrogen of 30 mg/ dl (10–15 mg/dl), creatinine of 1.15 mg/dl (0.60–1.10 mg/dl), and lactate dehydrogenase of 315 U/l (125–225 U/l). Other data were within normal limits, including beta-D glucan of < 6.0 pg/ ml (< 11.0 pg/ml) and circulating antibodies to HIV of 0.1 S/CO (< 1.0 S/CO). Intravenous piperacillin 2 g × 2/day was initiated for 1 week as an empirical treatment for bacterial cellulitis. Pairs of blood cultures were negative. One week later, intravenous merope-nem at 0.5 g × 2/day was administered. However, no improvement in the cellulitis of the left arm was perceived. Finally, histopathological observations of a skin biopsy specimen from the cellulitis with haematoxylin-eosin stain, Grocott stain and periodic acid-Schiff stain revealed yeast-like microbes 2 weeks after the administration of antibiotics. …

Recurrent bacteremia and liver abscess caused by Clostridium difficile: A case report.

Rationale: Clostridium difficile bacteremia (CDB) and liver abscess is a quite rare presentation of C. difficile infection. Patients concerns: A 74-year-old male with primary biliary cirrhosis and hepatocellular carcinoma who underwent transarterial chemoembolization (TACE) developed a high fever on post-TACE day 14. Intravenous ceftriaxone and following meropenem were administered, however, his clinical response was poor. On post-TACE day 24, 2 sets of blood culture were taken due to elevation of C-reactive protein levels. Diagnosis: CDB, caused by bacterial translocation. Interventions: Intravenous vancomycin and oral metronidazole were administered for two weeks. Outcomes: One month after recurrent CDB, the patient was re-admitted due to a liver abscess at the same site of TACE. C. difficile was isolated from the liver abscess and the patient received 6 weeks of oral metronidazole treatment. CDB and liver abscess have not recurred since completion of antibiotic treatment. Lessons: The spore-forming ability of C. difficile may contributed to the recurrent CDB episodes and liver abscess formation in necrotic liver tissue following TACE, and long-term metronidazole therapy was considered to be effective to C. difficile liver abscess.

Active surveillance in response to the identification of a single carbapenemase-producing Escherichia coli at a Japanese university hospital

This report described the experience of active surveillance culture implemented in response to the identification of a single carbapenemase-producing Escherichia coli in a Japanese university hospital. It revealed a horizontal transmission event and an additional asymptomatic carrier of carbapenemase-producing Escherichia coli with unique drug susceptibility and resistance gene profiles. Early implementation of active surveillance culture as a part of multifaceted infection control measures appeared to be useful to control further transmission of carbapenemase-producing Escherichia coli even in the low endemic facility. Further investigations on the timing and usefulness of active surveillance culture in the control of carbapenemase-producing Enterobacteriaceae would be warranted.

Fungal endocarditis after transcatheter aortic valve replacement (TAVR): Case report and review of literature

The reported number of transcatheter aortic valve replacement-associated infective endocarditis (TAVR-IE) cases has been increasing worldwide, but information about the incidence and clinical features of fungal TAVR-IE is quite limited. We present a patient who acquired TAVR-IE caused by Candida parapsilosis four month after TAVR, who was successfully treated redo-aortic valve replacement and prolonged antifungal therapy.

Automated detection of outbreaks of antimicrobial-resistant bacteria in Japan

BACKGROUND Hospital outbreaks of antimicrobial-resistant (AMR) bacteria should be detected and controlled as early as possible. AIM To develop a framework for automatic detection of AMR outbreaks in hospitals. METHODS Japan Nosocomial Infections Surveillance (JANIS) is one of the largest national AMR surveillance systems in the world. For this study, all bacterial data in the JANIS database were extracted between 2011 and 2016. WHONET, a free software for the management of microbiology data, and SaTScan, a free cluster detection tool embedded in WHONET, were used to analyse 2015-2016 data of eligible hospitals. Manual evaluation and validation of 10 representative hospitals around Japan were then performed using 2011-2016 data. FINDINGS Data from 1031 hospitals were studied; mid-sized (200-499 beds) hospitals accounted for 60%, followed by large hospitals (≥500 beds; 24%) and small hospitals (<200 beds; 16%). More clusters were detected in large hospitals. Most of the clusters included five or fewer patients. From the in-depth analysis of 10 hospitals, ∼80% of the detected clusters were unrecognized by infection control staff because the bacterial species involved were not included in the priority pathogen list for routine surveillance. In two hospitals, clusters of more susceptible isolates were detected before outbreaks of more resistant pathogens. CONCLUSION WHONET-SaTScan can automatically detect clusters of epidemiologically related patients based on isolate resistance profiles beyond lists of high-priority AMR pathogens. If clusters of more susceptible isolates can be detected, it may allow early intervention in infection control practices before outbreaks of more resistant pathogens occur.

Risk factors for and role of OprD protein in increasing minimal inhibitory concentrations of carbapenems in clinical isolates of Pseudomonas aeruginosa

Purpose. This study examined the risk factors for, and molecular mechanisms underlying, the increase in carbapenem minimum inhibitory concentrations (MICs) in clinical isolates of Pseudomonas aeruginosa. Methodology. Consecutive clinical isolates of P. aeruginosa were collected. The MicroScan WalkAway system detected more than fourfold increases in the MICs of carbapenems in P. aeruginosa isolates serially recovered from some patients during their clinical course. The clinical risk factors associated with this increase were examined by multiple logistic regression analysis. Western blot analysis and nucleotide sequencing of the oprD gene of 19 clonally related and paired P. aeruginosa isolates from the same patients were undertaken to examine the mechanisms underlying the increase in MICs. Results. The results showed that prior use of carbapenems (OR, 2.799; 95% CI, 1.088‐7.200; P=0.033) and the use of ventilators or tracheostomies (OR, 2.648; 95% CI, 1.051‐6.671; P=0.039) were risk factors for increased carbapenem MICs. Analysis of the underlying mechanisms revealed that loss of functional OprD protein due to mutation of the oprD gene tended to occur in P. aeruginosa isolates with imipenem MICs of more than 8 &mgr;g ml−1; a reduction in OprD expression was observed in P. aeruginosa isolates with imipenem MICs of 4 or 8 &mgr;g ml−1. This difference in the resistance mechanism was not correlated with the MICs of meropenem. Conclusion. This difference in the resistance mechanism of P. aeruginosa indicates a critical breakpoint at an imipenem MIC of 8 &mgr;g ml−1, in accordance with EUCAST criteria. Reducing carbapenem use will prevent P. aeruginosa clinical isolates from developing resistance to carbapenems.

Pneumococcal biliary tract infections – How rare are they?

Pneumococcal biliary tract infections (PBTIs) were reported as rare due to the bacteriums bile solubility. The purpose of this study was to determine the occurrence and clinical characteristics of PBTIs. A retrospective case series review was conducted from January 2006 to August 2014 at a tertiary referral university hospital in Japan. Patients with a blood or bile culture positive for Streptococcus pneumoniae diagnosed with definite cholangitis or cholecystitis according to Tokyo Guideline 2013 were enrolled in this study. Data on clinical information, treatments, and outcomes were collected. During 104 months, 48 cases of positive blood cultures and 13 cases of positive bile cultures were recorded, and after excluding 43 and 5 of these, respectively, a total of 10 patients were diagnosed with PBTI. Most patients (9/10) had biliary tract problems and biliary devices in place. PBTIs were not rare; conversely, they were a relatively common cause of pneumococcal bacteremia in this center treating a high volume of biliary tract illnesses.