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Eggerthella lenta is an important cause of anaerobic bloodstream infections and is associated with high mortality. However, there are few reports of E. lenta infection in Japan. This study aimed to evaluate the clinical and microbiological characteristics of bacteremia caused by E. lenta in Hiroshima, Japan. We retrospectively analyzed E. lenta bacteremia patients at the Hiroshima University Hospital between January 2012 and December 2020. During the study period, 14 patients with E. lenta bacteremia were identified. All E. lenta isolates were cultured in anaerobic bottles, and the median time to blood culture positivity was 52.9 h. In most cases (85.6%), the source of E. lenta bacteremia was associated with intra-abdominal infections, and colon perforation was the most frequent source of E. lenta bacteremia (42.9%, n = 6). Antimicrobial susceptibility testing showed high minimal inhibitory concentrations (MIC) of piperacillin-tazobactam (TZP) and 100% susceptibility to ampicillin-sulbactam, carbapenems, and metronidazole. This study demonstrates that E. lenta bacteremia is associated with intra-abdominal infections, particularly colon perforation, and a high MIC of TZP. When gram-positive anaerobes are detected in the blood cultures of patients with severe intra-abdominal infections, clinicians should suspect E. lenta, and it may be better to change antimicrobial agents from TZP.

Background The clinical effectiveness of ultraviolet light (UV) disinfection remains unclear. This study aimed to investigate the effect of adding pulsed xenon UV (PX-UV) disinfection to the terminal cleaning protocol on the rate of methicillin-resistant Staphylococcus aureus (MRSA) acquisition at a Japanese hospital. Methods The use of a PX-UV disinfection device was added to the manual terminal cleaning protocol applied after the discharge or transfer of patients treated in the intensive and high care units. We used a Poisson regression model to examine the incidence of MRSA acquisition, based on the study period, PX-UV intervention status, unit type, and the rate of consumption of alcohol-based hand rub (ABHR). Results Approximately 86% of the rooms in the intervention units were terminally disinfected with the PX-UV device. In the intervention units, the incidence of MRSA acquisition decreased from 3.56 per 1,000 patient-days in the nonintervention period to 2.21 per 1,000 patient-days in the intervention period. Moreover, the use of PX-UV disinfection decreased the risk of MRSA acquisition (incident rate ratio: 0.556; 95% confidence interval, 0.309-0.999; P = .0497). ABHR consumption did not affect the risk of MRSA acquisition. Conclusions Adding PX-UV disinfection to terminal manual cleaning reduced the rate of MRSA acquisition.

Staphylococcus pseudintermedius is commonly associated with skin and soft tissue infections in dogs. However, infections caused by S. pseudintermedius are only rarely reported in humans, and this pathogen is frequently misidentified as S. aureus. We herein report a case of an implanted port catheter system infection caused by methicillin-resistant S. pseudintermedius (MRSP) in a patient with hepatocellular carcinoma. The patient was also a dog owner. S. pseudintermedius was first identified using the Vitek2 system (BioMerieux). Whole-genome sequencing revealed that this MRSP was a sequence type 71-carrying staphylococcal cassette chromosome mec type III (ST71-SCCmec III) isolate.

Background Mobile phones may be contaminated with nosocomial pathogens such as methicillin-resistant Staphylococcus aureus (MRSA). The aim of this study was to investigate the MRSA contamination rate on doctors’ hospital-use-only mobile phones and the efficacy of 222-nm ultraviolet light (UV) disinfection. Methods We investigated the MRSA contamination rate of doctors’ hospital-use-only mobile phones, as well as the reduction in MRSA counts on plastic plates and aerobic bacteria (AB) on mobile phones before and after exposure to 222-nm UV irradiation. Results Five (10%) of the 50 mobile phones investigated were contaminated with MRSA. Exposure to 0.1 mJ/cm2 222-nm UVC irradiation for 1.5 and 2.5 min (9 and 15 mJ/cm2) achieved mean log10 MRSA colony-forming units reductions of 2.91 and 3.95, respectively. Exposure to 9 mJ/cm2 222-nm UVC irradiation (0.1 mW/cm2 for 1.5 minutes) significantly reduced AB contamination on mobile phones (P Conclusions The use of 222-nm UV disinfection resulted in effective in vitro reduction of MRSA and significantly reduced AB contamination of mobile phone surfaces.

Background Contaminated environmental surfaces are important sources of transmission for healthcare-associated pathogens, including Clostridioides (Clostridium) difficile. The effectiveness of manual bleach cleaning and pulsed xenon ultraviolet (PX-UV) disinfection on C. difficile contamination of hospital room high-touch surfaces in Japan was evaluated. Methods The environmental surfaces of 20 C. difficile infection (CDI) isolation rooms were sampled immediately after CDI patients were discharged or transferred. High-touch surfaces were sampled before and after either bleach cleaning or PX-UV disinfection in addition to nonbleach cleaning. Changes in the number of C. difficile-positive samples and bacterial counts for each cleaning method were assessed. Results Overall, 286 samples were collected (bleach cleaning, 144 samples; PX-UV disinfection, 142 samples). Before cleaning, the positive rates of C. difficile were 27.8% and 31.0% in bleach cleaning and PX-UV disinfection, respectively. Both bleach cleaning and PX-UV disinfection significantly reduced overall C. difficile-positive samples (P = .018 and P = .002, respectively) and C. difficile colony-forming unit counts (P = .002 and P = .001, respectively). Conclusions PX-UV disinfection in addition to manual nonbleach cleaning effectively reduces C. difficile contamination from high-touch surfaces. Further studies are warranted to evaluate the effect of PX-UV disinfection on CDI rates in Japanese hospitals.

Background Contamination of healthcare environments by multidrug-resistant organisms (MDRO) and Clostridioides difficile is a risk for healthcare-associated infections. The efficacy of pulsed xenon ultraviolet (PX-UV) disinfection in healthcare environments has been described previously. However, there are few reports about PX-UV disinfection in Japan. The aim of this study was to investigate in vitro the efficacy of PX-UV disinfection of MDRO and C. difficile spores commonly isolated in Japanese hospitals. Methods We investigated reductions in microbial counts after exposure to PX-UV of the following clinically-isolated organisms on seeding agar plates: methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus faecium, carbapenemase-producing Klebsiella pneumoniae, extended spectrum β-lactamase-producing Escherichia coli, multidrug resistant Acinetobacter baumannii, and C. difficile spores. We also visually assessed the attenuation of disinfection by shielding of MRSA and carbapenemase-producing K. pneumoniae from PX-UV exposure. Results PX-UV disinfection for 5 min induced >5-log colony-forming units (CFU)/cm2 growth inhibition of all the MDRO. PX-UV disinfection for 15 min induced >3-log CFU/cm2 growth inhibition of C. difficile spores. Where a plate was shielded from PX-UV exposure the bacteria showed confluent growth, but no colonies were observed on unshielded (exposed) parts of the plates. Conclusion This study shows the efficacy of PX-UV disinfection against clinical MDROs. C. difficile spores were more resistant to PX-UV disinfection than vegetative bacteria. Further evaluation of the efficacy of PX-UV disinfection in reducing the contamination of real-world surfaces and the incidence of healthcare-associated infections is needed.

Background For residents of long-term care facilities (LTCFs), antimicrobial-resistant bacteria (ARB) are a risk factor, yet their oral colonisation, potentially leading to aspiration pneumonia, remains unclear. This study was undertaken to survey the prevalence, phenotypic characteristics, and molecular epidemiology of antimicrobial-resistant Gram-negative bacteria in the oral cavity of LTCF residents, and to analyse the risk factors for such carriers. Methods This study involved 98 residents of a LTCF in Hiroshima City, Japan, aged between 55 and 101 years. Oropharyngeal swabs were collected and plated on screening media for ESBL-producing and carbapenem-resistant bacteria; isolates were identified and tested for antibiotic susceptibility; biofilm formation was tested in vitro; identification of epidemic clones were pre-determined by PCR; resistance genes, sequence types, and whole-genome comparison of strains were conducted using draft genome sequences. Demographic data and clinical characterisations were collected and risk factors analysed. Results Fifty-four strains from 38% of the residents grew on screening media and comprised predominantly of Acinetobacter spp. (35%), Enterobacteriaceae spp. (22%), and Pseudomonas spp. (19%). All Escherichia coli isolates carried CTX-M-9 group and belonged to the phylogroup B2, O25:H4 ST131 fimH30 lineage. Six Acinetobacter baumannii isolates presented identical molecular characteristics and revealed more biofilm production than the others, strongly suggesting their clonal lineage. One Acinetobacter ursingii isolate displayed extensive resistance to various ß-lactams due to multiple acquired resistance genes. One Pseudomonas aeruginosa isolate showed exceptional resistance to all ß-lactams including carbapenems, aminoglycosides, and a new quinolone, showing a multidrug-resistant Pseudomonas aeruginosa (MDRP) phenotype and remarkable biofilm formation. Genome sequence analysis revealed this isolate was the blaIMP-1-positive clone ST235 in Japan. Strokes (cerebral infarction or cerebral haemorrhage) and percutaneous endoscopic gastrostomy tubes were recognised as risk factors for oral colonisation by ARB in the LTCF residents. Conclusions ARB, as defined by growth on screening agar plates, which carried mobile resistance genes or elements or conferred high biofilm formation, were already prevalent in the oral cavity of LTCF residents. Health-care workers involved in oral care should be aware of antimicrobial resistance and pay special attention to transmission prevention and infection control measures to diminish ARB or mobile resistance elements dissemination in LTCFs.

Staphylococcus argenteus is a globally distributed cause of human infection; however, it has been misidentified as Staphylococcus aureus in diagnostic laboratories. Invasive infection caused by S. argenteus has been increasingly reported worldwide. However, there have been no reports on S. argenteus bacteremia in Japan. Therefore, we conducted a retrospective study to investigate the incidence of S. argenteus bacteremia at Hiroshima University Hospital between 2013 and 2017. S. argenteus was identified based on the absence of the crtM gene and multi-locus sequence typing. S. argenteus was identified in 2 of the 201 S. aureus blood culture isolates (1.0%). Both S. argenteus isolates belonged to sequence type 2250 harboring the staphylococcal enterotoxin Y gene (sey) and were susceptible to methicillin. One of them was penicillin-resistant, harboring a blaZ gene. The primary sites of infection were lower leg cellulitis and catheter-related blood stream infection. No patients died during hospitalization. This study suggested a low incidence of S. argenteus bacteremia in Japan when compared with reports from other countries. Further studies are necessary to investigate the prevalence of S. argenteus infection in Japan and the clinical impact of S. argenteus compared to S. aureus.

We retrospectively analyzed seven patients with Actinotignum schaalii bacteremia in a tertiary hospital in Japan. Pyelonephritis was the most frequent source of bacteremia, followed by Fournier's gangrene and pyometra. All patients with pyelonephritis had underlying urological conditions, ureteral stents, nephrostomy, ureteral stones, or ureterocele.

Recently, a new rapid assay for the detection of tcdB gene of Clostridioides difficile was developed using the GENECUBE. The assay can directly detect the tcdB gene from stool samples without a purification in approximately 35 minutes with a few minutes of preparation process. We performed a prospective comparative study of the performance of the assay at eight institutions in Japan. Fresh residual stool samples (Bristol stool scale ≥5) were used and comparisons were performed with the BD MAX Cdiff assay and toxigenic cultures. For the evaluation of 383 stool samples compared with the BD MAX Cdiff assay, the sensitivity, and specificity of the two assays was 99.0% (379/383), 98.1% (52/53), 99.1% (327/330), respectively. In the comparison with toxigenic culture, the total, sensitivity, and specificity were 96.6% (370/383), 85.0% (51/60), and 98.8% (319/323), respectively. The current investigation indicated the GENECUBE Clostridioides difficile assay has equivalent performance with the BD MAX Cdiff assay for the detection of tcdB gene of C. difficile.

Staphylococcus aureus is a relatively uncommon causative agent of urinary tract infection (UTI). However, the clinical features of S. aureus-related UTI are unclear. Thus, we aimed to clarify how patients with S. aureus bacteriuria develop UTI and determine the features and clinical risk factors of symptomatic S. aureus-related UTI. We performed a retrospective study of patients at the Hiroshima University Hospital for whom S. aureus had been isolated from urine culture from January 2010 to December 2017. The characteristics (age, sex, body mass index, indwelling catheterization, renal stones, hydronephrosis, anticancer drug use, diabetes mellitus, steroid use, serum albumin, antibiotic use in the past 1 month, estimated glomerular filtration rate, benign prostate hyperplasia, and neurogenic bladder) of patients with UTI and those without UTI were compared, and the risk factors for S. aureus-related UTI were identified by multiple logistic regression model. A total of 286 patients with S. aureus bacteriuria were analyzed; 33 patients developed UTI. The causative pathogens were methicillin-sensitive S. aureus and methicillin-resistant S. aureus (MRSA) in 14 and 19 patients, respectively, who developed UTI. This study demonstrated that indwelling catheterization, hydronephrosis, and renal stones are significantly associated with S. aureus-related UTI (p = 0.01, odds ratio = 3.1; and p

Aeromonas dhakensis, a newly recognized species, is often misidentified as A. hydrophila, A. veronii, or A. caviae by commercial phenotypic tests. Limited data about A. dhakensis are available in Japan. We retrospectively analyzed the patients with monomicrobial Aeromonas bacteremia at Hiroshima University Hospital from January 2011 to December 2017, and species re-identification was conducted using rpoD and gyrB gene sequencing and matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) system. Of the 19 strains from blood isolates, A. caviae (n = 9, 47.4%), A. dhakensis (n = 4, 21.1%), A. hydrophila (n = 3, 15.8%), and A. veronii (n = 3, 15.8%) were re-identified. A. dhakensis was phenotypically misidentified as A. hydrophila (n = 3, 75%) or A. sobria (n = 1, 25%). A. dhakensis was also misidentified as A. caviae (n = 2, 50%), A. hydrophila (n = 1, 25%), and A. jandaei (n = 1, 25%) in MALDI-TOF MS system. Malignancies (n = 12, 63.2%) and liver cirrhosis (n = 7, 36.8%) were common comorbidities. Biliary tract infection was the most frequent source of Aeromonas bacteremia (n = 11, 57.9%). The major source of A. dhakensis bacteremia was also biliary tract infection (n = 3, 75%), and the 14-day infection-related mortality of A. dhakensis was 25%. A. dhakensis isolates showed similar clinical characteristics, antimicrobial susceptibility, and mortality with those of other Aeromonas species isolates. This study demonstrated that A. dhakensis is not a rare cause of Aeromonas bacteremia, but is often misidentified as A. hydrophila in Hiroshima, Japan. Further studies should be conducted to identify the geographical distribution and clinical impact of A. dhakensis in Japan.

Global spread and evolutionary links of an epidemic Clostridium difficile strain (PCR-ribotype 027) have been noted in recent decades. However, in Japan, no outbreaks caused by type 027 have been reported to date. A total of 120 C. difficile isolates from patients at 15 hospitals during non-outbreak seasons between 2011 and 2013 as well as 18 and 21 isolates collected from two hospitals in 2010 and 2009, respectively, in outbreak periods in Japan, were examined. Among these 120 isolates, Japan-ribotypes smz and ysmz (subtype variant of smz) were the most predominant (39.2 %) followed by Japan-ribotype trf (15.8 %). Types smz/ysmz and trf were also concurrently predominant at two hospitals in the outbreak settings. Out of the five binary toxin-positive isolates observed, only one was PCR-ribotype 027 and another PCR-ribotype 078. Type smz was later found to correspond to PCR-ribotype 018. High rates of resistance against gatifloxacin, moxifloxacin, erythromycin and clindamycin were observed in the PCR-ribotype 018 isolates. Interestingly, all trf isolates were toxin A-negative, toxin B-positive, but they did not correspond to PCR-ribotype 017, thus being assigned a new ribotype (PCR-ribotype 369). In conclusion, PCR-ribotypes 018 (smz) and 369 (trf) were identified as major circulating strains in both outbreak and non-outbreak settings in Japan. Given their epidemiological relevance, molecular investigations are warranted to clarify potential evolutionary links with related strains found elsewhere, such as PCR-ribotypes 018 and 017 from Europe and North America.

This in vitro study examined the combined effects of double antibacterial drugs against multidrug-resistant Pseudomonas aeruginosa (MDRP). The tested clinical isolates from Hiroshima University Hospital were 40 strains which met the criteria for MDRP, that is, the minimum inhibitory concentration (MIC) wasor = 16 microg/mL of meropenem,or = 4 microg/mL of ciprofloxacin andor = 32 microg/mL of amikacin. Using the original checkerboard plates for colistin (CL), arbekacin (ABK), aztreonam (AZT), rifampicin (RFP) and piperacillin (PIPC), MIC values were determined for single and double combinations. Based on the MIC values, fractional inhibitory concentration index values were calculated and the combined effects (synergy action or additive action) were evaluated. The three strongest drugs among the tested combinations were i) CL + RFP (synergy, 80.0%; additive, 17.5%), ii) RFP + ABK (synergy, 7.5%; additive, 70.0%) and iii) RFP + AZT (synergy, 5.0%; additive, 77.5%). In these cases, the arithmetic mean MIC value of each drug significantly decreased as follows: i) 1.38 microg/mL (alone) and 0.26 microg/mL (with RFP) for CL, 19.85 microg/mL (alone) and 1.85 microg/mL (with CL) for RFP; ii) 19.85 microg/mL (alone) and 7.53 microg/mL (with ABK) for RFP, 8.87 microg/mL (alone) and 2.79 microg/mL (with RFP) for ABK; iii) 19.85 microg/mL (alone) and 10.15 microg/mL (with AZT) for RFP, 28.3 microg/ mL (alone) and 6.65 microg/mL (with RFP) for AZT. Of 40 strains, metallo-beta-lactamase and aminoglycoside 6'-N-acetyltransferase were found in 20 and 37 strains, respectively; however, no significant influence of these factors was observed on the combined effects of i), ii) and iii). The results of this study provide an in vitro rationale for RFP plus CL, ABK or AZT as an effective combination therapy for MDRP infections, although the results should be verified and compared with other antibacterial drugs in further studies.