Hiroki Namikawa

Hiroki Namikawa

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Hiroki Namikawa

Department of Medical Education and General Practice, Osaka Metropolitan University Graduate School of Medicine, 1-4-3, Asahi-machi, Abeno-ku, Osaka, 545-8585, Japan

Research Focus & Metrics

Academic Career Length

11Years (2016-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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21 February 2023 in Journal of Hospital Infection
Verified
Journal Article
Closed access
HNH. Namikawa
H. Namikawa
KOK.-I. Oinuma
K.-I. Oinuma
KYK. Yamada
K. Yamada
YKY. Kaneko
Y. Kaneko
HKH. Kakeya
H. Kakeya
TST. Shuto
T. Shuto

5 June 2023 in Emerging Microbes & Infections
Verified
Journal Article
Open access
HNHiroki Namikawa
Hiroki Namikawa
WIWaki Imoto
Waki Imoto
KYKoichi Yamada
Koichi Yamada
YTYoshihiro Tochino
Yoshihiro Tochino
YKYukihiro Kaneko
Yukihiro Kaneko
TSTaichi Shuto
Taichi Shuto
Extended-spectrum beta-lactamase-producing Enterobacteriaceae (ESBL-PE) bacteremia can have poor clinical outcomes. Thus, determining the predictors of mortality from ESBL-PE bacteremia is very important. The present systematic review and meta-analysis aimed to evaluate studies to determine predictors associated with ESBL-PE bacteremia mortality. We searched PubMed and Cochrane Library databases for all relevant publications from January 2000 to August 2022. The outcome measure was mortality rate. In this systematic review of 22 observational studies, 4607 patients with ESBL-PE bacteremia were evaluated, of whom 976 (21.2%) died. The meta-analysis showed that prior antimicrobial therapy (RR, 2.89; 95% CI, 1.22-6.85), neutropenia (RR, 5.58; 95% CI, 2.03-15.35), nosocomial infection (RR, 2.46; 95% CI, 1.22-4.95), rapidly fatal underlying disease (RR, 4.21; 95% CI, 2.19-8.08), respiratory tract infection (RR, 2.12; 95% CI, 1.33-3.36), Pitt bacteremia score (PBS) (per1) (RR, 1.35; 95% CI, 1.18-1.53), PBS ≥ 4 (RR, 4.02; 95% CI, 2.77-5.85), severe sepsis (RR, 11.74; 95% CI, 4.68-29.43), and severe sepsis or septic shock (RR, 4.19; 95% CI, 2.83-6.18) were found to be mortality predictors. Moreover, urinary tract infection (RR, 0.15; 95% CI, 0.04-0.57) and appropriate empirical therapy (RR, 0.39; 95% CI, 0.18-0.82) were found to be a protective factor against mortality. Patients with ESBL-PE bacteremia who have the aforementioned require prudent management for improved outcomes. This research will lead to better management and improvement of clinical outcomes of patients with bacteremia caused by ESBL-PE.

1 April 2022 in Journal of the Formosan Medical Association
Verified
Journal Article
Open access
HNHiroki Namikawa
Hiroki Namikawa
MNMakoto Niki
Makoto Niki
MNMamiko Niki
Mamiko Niki
KOKen-Ichi Oinuma
Ken-Ichi Oinuma
KYKoichi Yamada
Koichi Yamada
TSTaichi Shuto
Taichi Shuto
Klebsiella pneumoniae bacteremia-induced sepsis is a clinically important condition with a high mortality rate and various known virulence factors. However, studies on the association of these virulence factors with the occurrence of K. pneumoniae bacteremia-induced sepsis are scarce. We aimed to investigate clinical variables and virulence factors in patients with K. pneumoniae bacteremia-induced sepsis. We retrospectively reviewed the medical records of 76 patients with K. pneumoniae bacteremia between January 2012 and July 2017. Patients were divided into sepsis (n = 25) and non-sepsis (n = 51) groups. Patient background characteristics, antimicrobial regimens, and prognosis were evaluated. We assessed the distribution of virulence factors related to K. pneumoniae, such as mucoviscosity, capsular polysaccharide, and siderophores. Siderophore production levels were determined by measuring the orange halo zone on chrome azurol S agar plate assay. There were no intergroup differences in male-to-female ratio and age. Multivariable analysis revealed that siderophore production level (p < 0.01) was an independent predictor of K. pneumoniae bacteremia-induced sepsis. Furthermore, the optimal cut-off point of siderophore production to predict sepsis was 9.6 mm (sensitivity, 86%; specificity, 76%; AUC, 0.81). Siderophore production was an independent predictor of sepsis caused by K. pneumoniae bacteremia. The optimal cut-off point for siderophore production for sepsis occurrence prediction was 9.6 mm. To improve outcomes, patients with K. pneumoniae bacteremia-induced sepsis with high siderophore production levels should be managed prudently.

16 November 2016 in BMC Infectious Diseases
Verified
Journal Article
Open access
PDF file
HNHiroki Namikawa
Hiroki Namikawa
KYKoichi Yamada
Koichi Yamada
HFHiroki Fujimoto
Hiroki Fujimoto
KOKen-Ichi Oinuma
Ken-Ichi Oinuma
YTYoshihiro Tochino
Yoshihiro Tochino
HKHiroshi Kakeya
Hiroshi Kakeya
A few Japanese cases of hypermucoviscous Klebsiella pneumoniae (K. pneumoniae) invasive syndrome have recently been reported. Although extrahepatic complications from bacteremic dissemination have been observed, infected aneurysms are rare. Furthermore, the primary source of infection is generally a liver abscess, and is rarely the prostate. Therefore, we report two atypical cases of hypermucoviscous K. pneumoniae invasive syndrome. The first case was an 81-year-old Japanese man with no significant medical history, who was referred to our hospital for vision loss in his right eye. Contrast-enhanced whole-body computed tomography revealed abscesses in the liver and the prostate, and an infected left internal iliac artery aneurysm. Contrast-enhanced head magnetic resonance imaging revealed brain abscesses. Cultures of the liver abscess specimen and aqueous humor revealed K. pneumoniae with the hypermucoviscosity phenotype, which carried the magA gene (mucoviscosity-associated gene A) and the rmpA gene (regulator of mucoid phenotype A). We performed enucleation of the right eyeball, percutaneous transhepatic drainage, coil embolization of the aneurysm, and administered a 6-week course of antibiotic treatment. The second case was a 69-year-old Japanese man with diabetes mellitus, who was referred to our hospital with fever, pollakiuria, and pain on urination. Contrast-enhanced whole-body computed tomography revealed lung and prostate abscesses, but no liver abscesses. Contrast-enhanced head magnetic resonance imaging revealed brain abscesses. The sputum, urine, prostate abscess specimen, and aqueous humor cultures revealed K. pneumoniae with the hypermucoviscosity phenotype, which carried magA and rmpA. We performed enucleation of the left eyeball, percutaneous drainage of the prostate abscess, and administered a 5-week course of antibiotic treatment. Hypermucoviscous K. pneumoniae can cause infected aneurysms, and the prostate can be the primary site of infection. We suggest that a diagnosis of hvKP invasive syndrome should be considered in all patients who present with K. pneumoniae infection and multiple organ abscesses.

1 April 2023 in International Journal of Antimicrobial Agents
Verified
Journal Article
Closed access
HNHiroki Namikawa
Hiroki Namikawa
KOKen-Ichi Oinuma
Ken-Ichi Oinuma
KYKoichi Yamada
Koichi Yamada
YKYukihiro Kaneko
Yukihiro Kaneko
HKHiroshi Kakeya
Hiroshi Kakeya
TSTaichi Shuto
Taichi Shuto

7 June 2018 in Asia Pacific Family Medicine
Verified
Journal Article
Open access
PDF file
SKShigeki Kinuhata
Shigeki Kinuhata
YTYasuhiko Takemoto
Yasuhiko Takemoto
MSMariko Senda
Mariko Senda
SNShiho Nakai
Shiho Nakai
ETErika Tsumura
Erika Tsumura
SUSadahiko Uchimoto
Sadahiko Uchimoto
Detecting and treating dementia at an early stage are important. Although the Revised Hasegawa Dementia Scale (HDS-R) is commonly used to detect dementia, it takes about 10 min to complete. In contrast, the 1-min animal test (OMAT) takes only 1 min to complete and may be a helpful screening test for general practitioners in deciding whether to proceed with administering further diagnostic tests such as the HDS-R. We sought to examine the relationship between the OMAT and HDS-R scores, and determine the cut-off OMAT score that balanced the sensitivity and specificity in identifying HDS-R-positive patients. A total of 122 consecutive patients with diabetes who visited the outpatient clinic at the Fujiidera Municipal Hospital were enrolled. The patients underwent the OMAT and HDS-R on the same day. Tests were conducted in a single-blinded manner. The relationship between the OMAT and HDS-R scores was examined using Spearman’s rank correlation. Receiver operating characteristic curve analysis was performed to identify the optimal cut-off score of OMAT that will determine whether to proceed with further diagnostic tests. A strong positive correlation between the OMAT and HDS-R scores was observed (r = 0.70). The sensitivity and specificity of OMAT using cut-off scores of 12/13, 13/14, and 14/15 for HDS-R-positive patients were 0.87 and 0.66, 1.00 and 0.51, and 1.00 and 0.40, respectively among all the subjects. Similar results were obtained in a subgroup of subjects aged ≥ 65 years. A cut-off score of 13/14 on the OMAT balanced the sensitivity closest to 1.00 and allowed for the highest specificity for the HDS-R not only among all the patients, but also among just the patients aged ≥ 65 years. The OMAT may be an optimal screening test to determine whether to proceed with further diagnosis using HDS-R. Trial registration UMIN UMIN000025260. This study is retrospectively registered on December 13th, 2016