Hitoshi Miyamoto

Ehime University, Matuyama, Ehime, Japan

Are you Hitoshi Miyamoto?

Claim your profile

Publications (26)16.03 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Moraxella species are rare causative pathogens of severe sight-threatening keratitis. The aim of this study was to analyze the clinical presentation, predisposing risk factors, in vitro antimicrobial susceptibility, and treatment associated with Moraxella keratitis. We retrospectively reviewed 30 culture-proven cases of Moraxella keratitis from multiple centers in Japan. The mean age of the patients was 58.4 ± 23.4 years. The most common ocular conditions were contact lens wearing (5 patients, 16.7%) and trauma (3 patients, 10.0%). Seven patients had diabetes mellitus. Sixteen patients exhibited hypopyon in association with the corneal focus. Ring-shaped infiltration was found in 9 patients (30.0%), and irregular or amoebic-shaped infiltration was observed in 13 patients (43.3%). Eight patients (26.7%) showed small round infiltrates. All Moraxella isolates were sensitive to fluoroquinolones and aminoglycosides. All were treated with a combination ophthalmic solution containing a fluoroquinolone, tobramycin, and cefmenoxime. Although no patients developed corneal perforation, the response to treatment was slow in all cases; the mean treatment period was 41.9 days. In Japan, Moraxella keratitis occurs in patients with contact lens wear, trauma, and diabetes mellitus. It presents as a small, round, ring-shaped, irregularly shaped, or amoebic-shaped focus. Moraxella species exhibit good susceptibility to fluoroquinolones and aminoglycosides. Because the treatment response may be very slow, these agents should be continued for a long period of time.
    No preview · Article · May 2015 · Cornea
  • H. Miyamoto · S. Murakami · T. Nishimiya · K. Suemori · H. Tauchi
    [Show abstract] [Hide abstract]
    ABSTRACT: We examined staphylococcal coagulase types and homologous analysis using the DiversiLab repetitive-sequence-based PCR system in exfoliative toxin (ET)-producing Staphylococcus aureus. Twenty-two isolates (17 methicillin-sensitive Staphylococcus aureus (MSSA) and 5 methicillin-resistant Staphylococcus aureus (MRSA) isolates) obtained in our hospital from January 2012 and December 2013 were used. Three groups were classified according to the coagulase types and serotypes of ET. The first group (4 MSSA) showed coagulase type I and ET-A, and the second group (3 MSSA and 2 MRSA) showed coagulase type I and ET-B. The third group (10 MSSA and 3 MRSA) showed coagulase type V and ET-B. An analysis by DiversiLab demonstrated that homology was high in both the first and second groups. The homogenousness was high among the third group isolates except for the ocular isolates. In our hospital, three important groups were present according to a coagulase type and an ET type, and the homology of ocular isolates could be different from other materials isolates.
    No preview · Article · May 2015
  • [Show abstract] [Hide abstract]
    ABSTRACT: Bacteriological examinations were conducted of seven Arcanobacterium haemolyticum strains isolated from elderly patients with skin and soft tissue infections, such as cellulitis and skin ulcers. Streptococcus dysgalactiae or Gram-positive cocci were isolated together with A. haemolyticum from all patients. The strains were identified as A. haemolyticum based their being on catalase negative, reverse CAMP positive, and phospholipase D gene positive in the respective tests. Moreover, API Coryne and MALDI-TOF MS confirmed the identification of A. haemolyticum. All strains showed good susceptibility to minocycline, vancomycin, and β-lactam antibiotics, but several strains were resistant to gentamicin and levofloxacin.
    No preview · Article · Feb 2015 · Journal of Medical Microbiology
  • [Show abstract] [Hide abstract]
    ABSTRACT: Tsukamurella spp. infection is a rare but important cause of bacteremia in immunocompromised patients. The organism is an aerobic, Gram-positive, weakly acid-fast bacillus that is difficult to differentiate from other aerobic Actinomycetales by standard laboratory methods. Here, we report on the case of a 14-year-old patient with Hodgkin's lymphoma who, after intensive chemotherapy, developed Tsukamurella inchonensis bacteremia, which was identified on the peripherally inserted central venous catheter (PICC) using 16S rRNA sequencing analysis. The bacteremia was successfully controlled with antimicrobial therapy and subsequent removal of the PICC. This is the first report of bacteremia by Tsukamurella inchonensis in immunocompromised children. Careful observation and prompt analysis of opportunistic infection, including Tsukamurella spp., is very important in immunocompromised children. © 2015 Japan Pediatric Society.
    No preview · Article · Feb 2015 · Pediatrics International
  • Source

    Preview · Article · Jan 2015
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Background Beauveria bassiana is an entomopathogenic fungus and is a rare cause of keratitis. We present a case of fungal keratitis caused by B. bassiana that was diagnosed by in vivo confocal microscopy and in vitro corneal cultures. In addition, we determined the temperature- and drug-sensitivities of the isolated strain of B. bassiana. Case presentation A 59-year-old Japanese man with a 2-month history of keratitis was examined by slit-lamp biomicroscopy, in vivo confocal microscopy, and histology and cultures of corneal scrapings. The corneal scrapings were used to determine the minimal inhibitory concentrations of different antifungal drugs and also to determine the temperature-sensitivity. In vivo confocal microscopy and histological examinations showed filamentous fungal keratitis. The characteristics of the fungal growth indicated that the keratitis was caused by B. bassiana. The keratitis responded poorly to systemic and topical voriconazole and to natamycin ointment. However, it was resolved after changing the natamycin to micafungin combined with surgical debridement. The isolated strain was sensitive to itraconazole, miconazole, micafungin, voriconazole, and resistant to flucytosine and fluconazole. It was moderately sensitive to amphotericin B, and natamycin. After 7 days in culture, the isolate grew small white colonies at 25°C, very small colonies at 35°C and 37°C. Conclusion The drug-sensitivity and temperature-sensitivity profiles of B. bassiana should be helpful in the treatment of B. bassiana keratitis. Therapeutic surgery may be helpful for mycotic keratitis poorly responsive to medical therapy alone.
    Full-text · Article · Sep 2014 · BMC Research Notes
  • Hitoshi Miyamoto · Tatsuya Nishimiya

    No preview · Article · Mar 2014 · Kansenshogaku zasshi. The Journal of the Japanese Association for Infectious Diseases
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We report two cases of conjunctivitis caused by Neisseria gonorrhoeae with reduced cephalosporin susceptibility. Patients showed no response to cefmenoxime eye drops and intravenous ceftriaxone administration. The patients' condition improved after addition of oral minocycline. The isolates contained the mosaic penA for reduction of β-lactam susceptibility.
    Full-text · Article · Sep 2013 · Journal of clinical microbiology
  • [Show abstract] [Hide abstract]
    ABSTRACT: Reports of community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) infections have recently increased in Japan. To determine the status of MRSA infections in our hospital, we investigated their Staphylococcal cassette chromosome mec (SCCmec) types and prevalence of Panton-Valentine leukocidin (PVL). In addition, we investigated the relation between their SCCmec and antimicrobial susceptibility. The 191 strains were isolated from January to July in 2011 and were classified as SCCmec type I (2, 1.0%), type II (136, 71.2%), type IV (36, 18.8%), type V (4, 2.1%) and type VIII (2, 1.0%). Eleven isolates (5.8%) were designated as nontypable. No isolates were PVL-positive in this study. The SCCmec type IV strains were more susceptible to imipenem (MIC90, 0.25 μg/ml) than SCCmec type II strains (MIC90, >16 μg/ml). This difference was also observed between SCCmec type IV and SCCmec type II in susceptibility levels to clarithromycin, clindamycin, minocycline, and levofloxacin, but not to gentamicin. In particular, SCCmec type IV strains were susceptible to imipenem and minocycline. The result indicates these susceptibility is useful to discriminate CA-MRSA from Hospital-associated MRSA (HA-MRSA).
    No preview · Article · Apr 2013 · Rinsho Biseibutsu Jinsoku Shindan Kenkyukai shi = JARMAM: Journal of the Association for Rapid Method and Automation in Microbiology
  • [Show abstract] [Hide abstract]
    ABSTRACT: Unlabelled: Recent findings have focused on the possible role of linezolid (LZD) as a suitable candidate for the treatment of central nervous system infections. LZD treatment for meningitis has been sporadically reported in adults, but there are no reports in neonates or infants. We report a case of meningitis caused by methicillin-resistant Staphylococcus epidermidis (MRSE) in a neonatal girl. The patient had intraventricular hemorrhage on postnatal day 1 and was treated with ventricular drainage. Twenty-two days after drainage, the patient developed a fever and seizure. Although ampicillin and ceftriaxone were given empirically for meningitis, an increased cell count and protein were observed in cerebrospinal fluid (CSF). Vancomycin (VCM) was administered intravenously because MRSE was detected from CSF 2 days after the administration of ampicillin and ceftriaxone. However, intravenous administration of VCM did not show any effect. Subsequent treatment of LZD successfully reduced the cell count and protein in CSF. Conclusion: LZD may be a treatment option for neonates and infants for drain-associated meningitis caused by MRSE.
    No preview · Article · Feb 2013 · European Journal of Pediatrics
  • [Show abstract] [Hide abstract]
    ABSTRACT: The activity of antibacterial agents against aerobic Gram-positive cocci (25 genus or species, 1029 strains) and anaerobic bacteria (21 genus or species, 187 strains) isolated from clinical specimens in 2008 at 16 clinical facilities in Japan were studied using either broth microdilution or agar dilution method. The ratio of methicillin-resistant strains among Staphylococcus aureus and Staphylococcus epidermidis was 59.6% and 81.2%, suggesting that resistant strains were isolated at high frequency. Vancomycin (VCM), linezolid (LZD) and quinupristin/dalfopristin (QPR/DPR) had good antibacterial activity against methicillin-resistant S. aureus and methicillin-resistant S. epidermidis, with MIC90s of < or = 2 microg/mL. The ratio of penicillin (PC) intermediate and resistant strains classified by mutations of PC-binding proteins among Streptococcus pneumoniae was 92.0% that was highest among our previous reports. Cefpirome, carbapenems, VCM, teicoplanin (TEIC), LZD and QPR/DPR had MIC90s of < or = 1 microg/mL against PC-intermediate and resistant S. pneumoniae strains. Against all strains of Enterococcus faecalis and Enterococcus faecium, the MICs of VCM and TEIC were under 2 microg/mL, and no resistant strain was detected, suggesting that these agents had excellent activities against these species. 15.9% of E. faecalis strains and 1.2% of E. faecium strains showed intermediate to LZD. 17.1% of E. faecium strains showed intermediate or resistant to QPR/DPR. Against all strains of Clostridium difficile, the MIC of VCM was under 1 microg/mL, suggesting that VCM had excellent activity. Carbapenems showed good activity against Clostridiales, Bacteroides spp., and Prevotella spp., but one strain of Bacteroides fragilis showed resistant to carbapenems. And so, the susceptibility of this species should be well-focused in the future at detecting continuously.
    No preview · Article · Feb 2012 · The Japanese journal of antibiotics
  • [Show abstract] [Hide abstract]
    ABSTRACT: We determined MICs of antibacterial agents against 1145 clinical strains of aerobic Gram-negative bacteria (22 species) isolated at 16 Japanese facilities in 2008. MICs were determined using mostly broth microdilution method and antibacterial activity was assessed. Strains producing extended-spectrum beta-lactamases (ESBL) accounted for 3.8% of Escherichia coli, 2.6% of Klebsiella pneumoniae, 6.8% of Klebsiella oxytoca, 5.5% of Proteus mirabilis and 1.8% of Proteus vulgaris. ESBL produced strains were 6.8% at K. oxytoca that increased compared with 3.2% and 5.5% at P. mirabilis that decreased compared with 18.8% in 2006. Among Haemophilus influenzae, 61.7% that decreased compared with 67.7% in 2006, equaled 58.7% in 2004, were strains when classified by penicillin-binding protein 3 mutation. Against Pseudomonas aeruginosa, the activity of most antibacterial agents was similar to that in 2006. Although two antibacterial agents that tobramycin showed an MIC90 of 1 microg/mL and doripenem showed an MIC90 of 4 microg/mL against P. aeruginosa have potent activity. Of all P. aeruginosa strains, 4.3% were resistant to six agents of nine antipseudomonal agents, that decreased compared to 12.2% in 2004 and 5.7% in 2006. Against other glucose-non-fermentative Gram-negative rods, the activity of most antibacterial agents was similar to that in 2006.
    No preview · Article · Feb 2012 · The Japanese journal of antibiotics

  • No preview · Article · Jan 2012 · Geriatrics & Gerontology International
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: To determine the characteristics of the keratitis due to Colletotrichum gloeosporioides. The medical records of 3 cases of fungal keratitis caused by C. gloeosporioides were reviewed to determine the clinical characteristics. The minimal inhibitory concentrations of different antifungal drugs for all 3 isolates were determined. All 3 isolates were grown on Sabouraud dextrose agar at 25°C, 35°C, and 37°C to determine the temperature-sensitive growth. All 3 patients lived in the southwestern part of Japan and had an ocular trauma involving organic materials. The infectious foci were localized in the anterior stroma, and they did not extend deep into the stroma in all cases. The keratitis was treated with antifungal medications including topical voriconazole and natamycin eye ointment, and was resolved in 2-3 weeks. All of the isolated strains grew well at 25°C but poorly at 35°C and 37°C. All isolated strains had similar drug-sensitivity profiles; they were sensitive to amphotericin B, itraconazole, miconazole, micafungin, and voriconazole, and relatively resistant to flucytosine, fluconazole, and natamycin. All 3 cases of C. gloeosporioides keratitis had similar clinical features. The similarities in the drug-sensitivity profiles should be helpful in treating C. gloeosporioides keratitis.
    Full-text · Article · Jul 2011 · Journal of ocular pharmacology and therapeutics: the official journal of the Association for Ocular Pharmacology and Therapeutics
  • [Show abstract] [Hide abstract]
    ABSTRACT: The antibacterial activity of meropenem (MEPM) and other parenteral antibiotics against clinical isolates of 2655 strains including 810 strains of Gram-positive bacteria, 1635 strains of Gram-negative bacteria, and 210 strains of anaerobic bacteria obtained from 30 medical institutions during 2009 was examined. The results were as follows; (1) MEPM was more active than the other carbapenem antibiotics tested against Gram-negative bacteria, especially against enterobacteriaceae and Haemophilus influenzae. MEPM was also active against most of the species tested in Gram-positive and anaerobic bacteria, except for multidrug resistant strains including methicillin-resistant Staphylococcus aureus (MRSA). (2) MEPM maintained potent and stable antibacterial activity against Pseudomonas aeruginosa. The proportion of MEPM-resistant strains to ciprofloxacin-resistant strains or imipenem-resistant strains were 53.1% and 58.0% respectively. (3) The proportion of extended-spectrum beta-lactamase (ESBL) strains was 3.1% (26 strains) in enterobacteriaceae. And the proportion of metallo-beta-lactamase strains was 2.0% (6 strains) in P. aeruginosa. (4) Of all species tested, there were no species except for Bacteroides fragilis group, which MIC90 of MEPM was more than 4-fold higher than those in our previous study. Therefore, there is almost no significant decrease in susceptibility of clinical isolates to meropenem. In conclusion, the results from this surveillance study suggest that MEPM retains its potent and broad antibacterial activity and therefore is a clinically useful carbapenem for serious infections treatment at present, 14 years passed after available for commercial use in Japan.
    No preview · Article · Apr 2011 · The Japanese journal of antibiotics
  • [Show abstract] [Hide abstract]
    ABSTRACT: We determined MICs of antibacterial agents against 1280 clinical strains of aerobic Gram-negative bacteria (19 genus or species) isolated at 16 Japanese facilities in 2006. MICs were determined using mostly broth microdilution method and antibacterial activity was assessed. Strains producing extended-spectrum beta-lactamases (ESBL) accounted for 3.7% of Escherichia coli, 2.7% of Klebsiella spp., and 11.4% of Proteus spp. Notably, 18.8% of Proteus mirabilis was found to produce ESBL higher than 16.7% in 2004. This result was higher extremely than other species. Among Haemophilus influenzae, only 1.2% produced beta-lactamase and 62.8% that increased compared with 57.7% in 2004, were beta-lactamase-negative ampicillin-resistant strains when classified by penicillin-binding protein 3 mutation. Although few antibacterial agents against Pseudomonas aeruginosa have potent activity, only three agents--doripenem, ciprofloxacin, and tobramycin-showed an MIC90 of 4 microg/mL. Of all P aeruginosa strains, 5.7% were resistant to six or more agents of nine antipseudomonal agents, a decrease compared to 8.7% in 2004. Against other glucose-non-fermentative Gram-negative bacteria, the activity of most antibacterial agents was similar to that in 2004.
    No preview · Article · Dec 2010 · The Japanese journal of antibiotics
  • [Show abstract] [Hide abstract]
    ABSTRACT: The activity of antibacterial agents against aerobic Gram-positive cocci (26 species, 1022 strains) and anaerobic bacteria (23 species, 184 strains) isolated from clinical specimens in 2006 at 16 clinical facilities in Japan were studied using either broth microdilution or agar dilution method. The ratio of methicillin-resistant strains among Staphylococcus aureus and Staphylococcus epidermidis was 53.0% and 65.8%, suggesting that resistant strains were isolated at high frequency. Vancomycin (VCM) and quinupristin/dalfopristin (QPR/DPR) had good antibacterial activity against methicillin-resistant S. aureus and methicillin-resistant S. epidermidis, with MIC90s of < or = 2 micrcog/mL. The ratio of penicillin (PC) intermediate and resistant strains classified by mutations of PC-binding proteins among Streptococcus pneumoniae was 87.6%. Ceftriaxone, cefpirome, cefepime, carbapenem antibiotics, VCM, teicoplanin, linezolid(LZD) and QPR/DPR had MIC90s of < or = 1 microg/mL against PC-intermediate and resistant S. pneumoniae strains. Against all strains of Enterococcus faecalis and Enterococcus faecium, the MICs of VCM and TEIC were under 2 microg/mL, and no resistant strain was detected, suggesting that these agents had excellent activities against these species. 10.9% of E. faecalis strains or 3.5% of E. faecium strains showed intermediate or resistant to LZD. 24.4% of E. faecium strains showed intermediate or resistant to QPR/DPR. Against all strains of Clostridium difficile, the MIC of VCM were under 1 microg/mL, suggesting that VCM had excellent activity against C. difficile. Carbapenems showed good activity against Peptococcaceae, Bacteroides spp., and Prevotella spp. However since several strains of Bacteroides fragilis showed resistant to carbapenems and the susceptibility of this species should be well-focused in the future.
    No preview · Article · Dec 2010 · The Japanese journal of antibiotics
  • [Show abstract] [Hide abstract]
    ABSTRACT: While it is necessary to use antifungal drugs for opportunistic deep mycosis in patients with immune system dysfunction,the inappropriate use of such drugs needs to be reduced to prevent occurrence of antifungal drug resistance as well as from the pharmacoeconomic viewpoint.In this study,we evaluated a notification system for the proper use of antifungal drugs that was introduced at Ehime University Hospital in January 2008.We investigated changes in antimicrobial use densities (AUD) of antifungal drugs,dosage period,number of patients receiving them and average dosage period of antifungal drugs in β-D glucan negative or unidentified patients from January 2007 to December 2008.After the introduction of the notification system,there was a significant decrease in the average monthly AUD of antifungal drugs (from 12.8±1.8 to 7.6± 1.8 ; p<0.01).The number of patients treated with antifungal drugs for periods of over 12 days and the average dosage period of antifungal drugs in β-D glucan negative or unidentified patients also decreased (p<0.05).These results suggested that the notification system was effective in reducing purposeless empirical therapy and ensuring the proper use of antifungal drugs in our hospital.
    No preview · Article · Jan 2010
  • [Show abstract] [Hide abstract]
    ABSTRACT: This study was undertaken in order to evaluate the effectiveness of interventions by the Department of Infection Control and Prevention in promoting the proper use of antibiotic drugs for methicillin resistant Staphylococcus aureus (MRSA) prescribed to inpatients.We performed 3 interventions : 1.Protocol improvement for anti-MRSA drug use ; 2.Change in alcohol-based handrub and training in hand hygiene and 3.Devised reporting system for drug use.The effects of the interventions were determined by segmented regression analysis of interrupted time series for drug usage and cost before and after the interventions were commenced.The change in slope of drug use was -1.05 vials/1000 inpatients per month (95% Confidence interval (C.I.) -2.84,0.74)and the change in level was -8.21 vials/1000 inpatients (95% C.I.-14.67,-1.75).There was a significant decrease in the ratio of the patients receiving anti-MRSA drugs to MRSA incidence between before and after the interventions.These results suggested that usage of anti-MRSA drugs was immediately reduced by the interventions to promote the proper use of drugs.An ordinary estimate of reduction in costs was ¥29 million per year while a more conservative estimate produced a decrease of ¥20 million per year.These findings suggest that monitoring antimicrobial use and promoting the proper use of antibiotics for MRSA are important roles for pharmacists to perform.
    No preview · Article · Jan 2010
  • [Show abstract] [Hide abstract]
    ABSTRACT: To report a case of fungal keratitis caused by Colletotrichum gloeosporioides, which is a rare pathogen in humans. An 80-year-old woman developed fungal keratitis after having sustained a traumatic injury during field work. The patient was initially examined by slit-lamp biomicroscopy and the Heidelberg Retina Tomograph II-Rostock Cornea Module (HRT II-RCM). Corneal scrapings were collected and submitted for laboratory investigations. Many septate, hyphae-like interlocking and branching white lines were observed in the area of the infiltrate by HRT II-RCM. A tentative diagnosis of fungal keratitis was made, and the patient was treated with systemic and topical voriconazole and pimaricin ophthalmic ointment. The infectious focus resolved within 2 weeks, and there were no signs of a recurrence after 3 months of treatment with the antifungal agents. The culture of the corneal scraping grew C. gloeosporioides. HRT II-RCM was useful in detecting filamentous fungi in the cornea. The treatment with voriconazole and pimaricin was effective in the treatment of C. gloeosporioides keratitis.
    No preview · Article · Dec 2009 · Journal of ocular pharmacology and therapeutics: the official journal of the Association for Ocular Pharmacology and Therapeutics