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1 - 15 of 15 for "Hidemasa Nakaminami"
Virucidal activity of olanexidine gluconate against SARS-CoV-2
Antiseptics have been used for infection control against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Ethanol (EtOH) was found to be effective against SARS-CoV-2 while chlorhexidine gluconate (CHG) was less effective. Therefore virucidal activity may differ between different classes of antiseptic agents. In this study the efficacy of antiseptics against SARS-CoV-2 was evaluated and effective agents for infection control were identified. The following antiseptics were used in this study: 1.5% olanexidine gluconate (OLG); 80% EtOH; 1% sodium hypochlorite (NaClO); 0.2% benzalkonium chloride (BKC); 1% povidone-iodine (PVP-I); 0.5% 1% and 1.5% CHG; and 0.5% alkyldiaminoethylglycine hydrochloride (AEG). The virucidal activity was evaluated at 0 0.5 1 2 and 3 min according to EN14476. After 0.5 min of exposure 1.5% OLG 80% EtOH 1% NaClO 0.2% BKC and 1% PVP-I inactivated SARS-CoV-2 below the detection limit. The virus survived in the presence of 0.5% CHG 1% CHG or 0.5% AEG for 3 min. The virucidal activity of 1.5% CHG was insufficient after 0.5 min of exposure. The results showed that virucidal activity against SARS-CoV-2 differs depending on the class of antiseptic agents used under clean conditions. Despite belonging to the same class of biguanide antiseptics OLG was more effective against SARS-CoV-2 than CHG.
Preprint: Virucidal activity of olanexidine gluconate against SARS-CoV-2
Introduction: Antiseptics have been used for infection control against SARS-CoV-2. Ethanol (EtOH) was effective against SARS-CoV-2 while chlorhexidine gluconate (CHG) was less effective. Therefore there may be differences in virucidal activity between classes of antiseptic agents. Aim: In this study we evaluated the efficacy of antiseptics against SARS-CoV-2 and identified effective agents for infection control. Methods: The following antiseptics were used in this study: 1.5% olanexidine gluconate (OLG); 80% EtOH; 1% sodium hypochlorite (NaClO); 0.2% benzalkonium chloride (BKC); 1% povidone-iodine (PVP-I); 0.5% 1% and 1.5% chlorhexidine gluconate (CHG); and 0.5% alkyldiaminoethylglycine hydrochloride (AEG). Virucidal activity was evaluated at 0 30 s 1 2 and 3 min according to EN14476. Results: After 30 s of exposure 1.5% OLG 80% EtOH 1% NaClO 0.2% BKC and 1% PVP-I inactivated SARS-CoV-2 below the detection limit. In contrast the virus was survived in 0.5% CHG 1% CHG and 0.5% AEG after 3 min of exposure. However the virucidal activity of 1.5% CHG was insufficient after 30 s of exposure. Conclusion: This study showed that the virucidal activity against SARS-CoV-2 differs depending on the class of antiseptic agent. Despite belonging to the same class of biguanide antiseptics OLG was more effective against SARS-CoV-2 than CHG.
Genomic characterization of Haemophilus influenzae harbouring an exogenous resistance gene
Introduction. Reports of β-lactamase-producing Haemophilus influenzae are increasing worldwide.
Aim. This study aimed to elucidate the molecular characteristics and evolution of β-lactamase-producing H. influenzae.
Methodology. A total of 159 clinical isolates were characterized using multi-locus sequence typing. Antimicrobial resistance genes and integrative and conjugative element (ICE) types were identified through PCR and DNA sequencing. The genetic structure of ICE was further investigated using whole-genome sequencing.
Results. Out of 159 clinical isolates 20.8% (n=33) were β-lactamase producers. Thirteen sequence types (STs) were identified. ST 103 155 165 and 388 have been identified in previous studies suggesting that strains with these STs tend to acquire the β-lactamase gene bla TEM-1. Among β-lactamase producers 66.7% (n=22) of bla TEM-1 were located on ICE. The ICEs could be classified into two groups based on their sequence (types I and II). Among these strains 2017-Y3 harboured a macrolide resistance gene mef (A/E) in ICE. A comparative analysis of the ICE region of this strain and those from other countries suggested that each isolate was derived from ICE type I or II. These regions including mef (A/E) were similar to those of Tn6822 which is commonly found in Streptococcus.
Conclusions. This study revealed several STs associated with the acquisition of β-lactamase genes on ICEs. Additionally ICE evolution involved the acquisition of exogenous genes. The accumulation of resistance genes in ICE raises concerns regarding the emergence of multidrug-resistant H. influenzae.
Prosthetic valve endocarditis due to highly beta-lactam-resistant Streptococcus oralis: a case report
There are limited reports of patients with prosthetic valve infective endocarditis (IE) or recurrent IE due to highly beta-lactam-resistant viridans group streptococci. We present a case in which a patient with native valve IE due to beta-lactam-susceptible Streptococcus oralis developed prosthetic valve IE due to highly beta-lactam-resistant S. oralis . A 79-year-old man with a history of native aortic valve IE caused by beta-lactam-susceptible S. oralis 21 months prior to admission and aortic valve replacement was admitted to our hospital with a 2-week history of general malaise and low-grade fever. Transesophageal echocardiography showed a 20 mm vegetation on the prosthetic aortic valve and emergency cardiovascular surgery was performed on admission day 2. Three sets of blood cultures on admission were positive for highly beta-lactam-resistant S. oralis . Vancomycin and cefazolin were administered as initial treatment. After the surgery the patient was given vancomycin and gentamicin for 2 weeks followed by vancomycin for 4 weeks. He was relapse-free at the 6-month follow-up. For patients with native valve IE due to S. oralis who have undergone valve replacement more than 1 year earlier given the possibility of methicillin-resistant Staphylococcus aureus as well as S. oralis resistance to beta-lactams it may be advisable to start vancomycin as an initial treatment and continue it until the infecting micro-organism has been proven to be susceptible to beta-lactams.
Development of skin sebum medium and inhibition of lipase activity in Cutibacterium acnes by oleic acid
Cutibacterium acnes is associated with the exacerbated inflammation of acne vulgaris which occurs through the immune induction and pathogenicity factor production. Sebum which is not present in the growth medium currently used to study acne is present in acne pustules in differing concentrations among the pathological stages such as the initial formation and inflammatory phase. To evaluate the effect of C. acnes on inflammation exacerbation in acne pustules in vitro we developed an skin sebum medium containing artificial sebum and studied the growth and pathogenicity factor production of C. acnes in the skin sebum medium.
The growth and lipase activity of C. acnes ATCC11828 were tested using skin sebum medium containing different sebum concentrations. Only lipase activity decreased in the skin sebum medium culture containing 0.5 % sebum when compared with that without sebum while both growth and lipase activity decreased in cultures with 1.0 % sebum. Therefore the growth and lipase activity of C. acnes changed in the presence of sebum. Furthermore when the growth and lipase activity of C. acnes were tested in skin sebum medium containing sebum components unsaturated fatty acids such as oleic acid and triolein led to a decrease in lipase activity without inducing a change in growth. In the presence of oleic acid C. acnes lipase activity decreased noncompetitively in a concentration-dependent manner.
Our data showed that C. acnes growth and lipase activity changed upon sebum addition to the skin sebum medium and acne inflammation caused by C. acnes needs to be studied under conditions similar to those in acne pustules.
Chinese herbal medicines and nutraceuticals inhibit Pseudomonas aeruginosa biofilm formation
Pseudomonas aeruginosa is a major biofilm-forming opportunistic pathogen. Tolerance to antimicrobial agents due to biofilm formation may lead to the emergence of antimicrobial-resistant bacterial strains. Thus adjunctive agents that can inhibit biofilm formation are necessary to enhance the therapeutic efficacy of antimicrobial agents. In this study we evaluated the anti-biofilm formation activity of selected Chinese herbal medicines and nutraceuticals which are commercially available in Japan. Among the eight agents evaluated for their potential to inhibit biofilm formation Eiekikaryu S Iribakuga and Hyakujunro significantly reduced P. aeruginosa biofilm formation (P <0.05) without inhibiting bacterial growth. Additionally the expression of biofilm-associated genes (rhlR rhlA and lasB) in P. aeruginosa was significantly suppressed by Eiekikaryu S Iribakuga and Hyakujunro (P <0.001). Our findings indicate that some Chinese herbal medicines and nutraceuticals can be potential adjunctive agents for antimicrobial therapy against P. aeruginosa .
Comparison of the bactericidal effects of quinolones against low-susceptible Haemophilus influenzae
The increasing incidence of Haemophilus influenzae with decreased susceptibility to quinolones (quinolone low-susceptible H. influenzae ) in Japan has raised concerns about therapeutic failure. Thus assessment of effective antimicrobial agents is necessary to establish an effective therapeutic strategy against resulting infections. In this study in vitro bactericidal effects of quinolones on low-susceptible H. influenzae strains were evaluated using time-kill curve analysis. For tosufloxacin log reduction values for low-susceptible strains were significantly lower than those for susceptible strains at both Cmax and 1/2 Cmax. Conversely although the log reduction values were lower for susceptible strains the Cmax of levofloxacin and β-lactams (amoxicillin and cefditoren) indicated bactericidal effects. In addition higher concentrations of tosufloxacin at 2×Cmax and 4×Cmax had bactericidal effects on not only susceptible but also low-susceptible strains. These data strongly suggest that we should consider the presence of low-susceptible strains and reconsider the appropriate dosage of tosufloxacin for treatment especially for paediatric patients.
In vitro growth-inhibitory effects of Portulaca oleracea L. formulation on intestinal pathogens
Introduction. Empirical evidence suggests that Portulaca oleracea L. treats enteric infections including dysentery cholera and acute infectious gastroenteritis.
Aim. The aim of this study is to clarify the growth-inhibitory effects of Portulaca oleracea L. extract against 56 strains of intestinal pathogens.
Methodology. ‘Gogyo-so-cha (GSC)’ was used as the P. oleracea L. formulation. A growth curve analysis was used to measure the growth-inhibitory effects of GSC and Shiga toxin induction was measured using the latex agglutination test.
Results. GSC demonstrated strong bactericidal effects against Shigella dysenteriae and Vibrio cholerae strains from various isolates. GSC demonstrated weak or no bactericidal effects against intestinal commensal bacteria including Enterococcus spp. and Escherichia coli . GSC did not induce Shigella toxins.
Conclusion. GSC significantly inhibited the growth of intestinal pathogens including S. dysenteriae and V. cholerae without adversely affecting the intestinal flora supporting the usage of GSC in traditional Chinese medicine. Taken together GSC would be of immense value in the developing world where diarrhoeal infectious diseases continue to pose a major health risk.
Fast-acting bactericidal activity of olanexidine gluconate against qacA/B-positive methicillin-resistant Staphylococcus aureus
The qacA/B gene is one of the major determinants of resistance to antiseptics in methicillin-resistant Staphylococcus aureus (MRSA). Here we compared the fast-acting bactericidal activity of skin antiseptics including olanexidine gluconate (OLG) a new biguanide antiseptic agent introduced in Japan against clinical qacA/B-positive MRSA strains by determination of minimum bactericidal concentration and time–kill assay. Our findings provide for the first time data indicating that the fast-acting bactericidal activity of OLG against qacA/B-positive MRSA is higher than that of chlorhexidine gluconate even though both are biguanide antiseptics.
Impact of the introduction of a 13-valent pneumococcal vaccine on pneumococcal serotypes in non-invasive isolates from 2007 to 2016 at a teaching hospital in Japan
Purpose. To prevent severe invasive pneumococcal infection pneumococcal conjugate vaccines (PCVs) were introduced in Japan in 2010 and in 2013 a pneumococcal 13-valent conjugate vaccine (PCV13) was included in the routine vaccination schedule for infants. In this study we analysed the antimicrobial susceptibilities and capsular types of pneumococci isolated from non-invasive patient sites from 2007 to 2016 to assess the impact of the introduction of PCV13.
Methodology. A total of 618 pneumococcal isolates collected at a teaching hospital from 2007 to 2016 were used. These isolates were characterized by capsular typing multilocus sequence typing and antimicrobial susceptibility testing.
Results. Capsular typing indicated that after the introduction of the PCV the proportion of PCV13 serotypes decreased (P<0.01) while non-PCV13 serotypes became diverse. In particular increases in 22 F 15A and 23A were noted among non-PCV13 serotypes. Regarding antimicrobial susceptibility the non-susceptibility rate to penicillin of pneumococci that showed higher minimum inhibitory concentrations (MICs) than the susceptibility breakpoint decreased and pneumococci tended to become susceptible. However all type 23A pneumococci and 77.8 % of type 15A pneumococci showed the reverse trend with low susceptibility to penicillin. Furthermore all 15A and 23A isolates had macrolide resistance genes.
Conclusion. These data suggest that PCVs can prevent infections caused by PCV serotypes. However since non-PCV13-type pneumococci in particular 15A and 23A which have acquired multidrug resistance have already emerged over time the development of a novel vaccine targeting a broader spectrum of pneumococci is warranted.
Characterization of SCCmec type IV methicillin-resistant Staphylococcus aureus clones increased in Japanese hospitals
Recently the prevalence of staphylococcal cassette chromosome mec (SCCmec) type IV isolates which are the major community-acquired methicillin-resistant Staphylococcus aureus (MRSA) have increased in Japanese hospitals. The aim of this study was to elucidate the detailed molecular epidemiological features of the SCCmec type IV clones in Japanese hospitals. When 2589 MRSA isolated from four hospitals in Tokyo Japan between 2010 and 2014 were analysed the proportion of SCCmec type IV overtook that of type II which was the major type of hospital-acquired MRSA in 2014. Multilocus sequence typing showed that CC1 was the most predominant clone in the SCCmec type IV isolates. The clinical departments that the patients belonged to pulsed-field gel electrophoresis analysis and antimicrobial susceptibility profiles suggested that the origin of the CC1-SCCmec type IV (CC1-IV) clone was a community setting. Our data show that the CC1-IV clone is becoming a predominant MRSA clone in Japanese hospitals.
Propionibacterium acnes is developing gradual increase in resistance to oral tetracyclines
Propionibacterium acnes is an anaerobic bacterium that causes deep infection in organs and prosthetic joints in addition to acne vulgaris. Many tetracycline-resistant P. acnes strains have been isolated because oral tetracyclines are frequently used as an acne treatment against P. acnes. In this study we found a novel tetracycline resistance mechanism in P. acnes. Three doxycycline-resistant (MIC: 16 µg ml−1) strains were isolated from 69 strains in acne patients in Japan between 2010 and 2011. Additionally six insusceptible strains (MIC: 1–2 µg ml−1) that had reduced susceptibility compared to susceptible strains (MIC: ≤0.5 µg ml−1) were identified. All doxycycline-resistant strains had a G1036C mutation in the 16S rRNA gene in addition to an amino acid substitution in the ribosomal S10 protein encoded by rpsJ. By contrast insusceptible strains had an amino acid substitution in the S10 protein but no mutation in the 16S rRNA. When the mutant with decreased susceptibility to doxycycline was obtained in vitro only the mutated S10 protein was found (MIC: 4 µg ml−1) not the mutated 16S rRNA gene. This result shows that the S10 protein amino acid substitution contributes to reduced doxycycline susceptibility in P. acnes and suggests that tetracycline resistance is acquired through a 16S rRNA mutation after the S10 protein amino acid substitution causes reduced susceptibility.
Increase in SCCmec type IV strains affects trends in antibiograms of meticillin-resistant Staphylococcus aureus at a tertiary-care hospital
The prevalence of community-acquired meticillin-resistant Staphylococcus aureus (CA-MRSA) strains has become a serious problem worldwide. The aim of this study was to investigate the annual transitions of MRSA strains with the CA-MRSA feature which were identified as SCCmec type IV or V in a hospital setting in Japan. Between 2005 and 2012 MRSA strains were collected from a tertiary-care hospital in Tokyo Japan and SCCmec typing detection of the virulence factors and antimicrobial susceptibility testing were conducted. The rate of detection of type II SCCmec which is found mainly in healthcare-associated MRSA significantly decreased from 90.0 (2005–2006) to 74.3 % (2011–2012) (P < 0.01). In contrast the rate of detection of type IV SCCmec which is mainly found in CA-MRSA significantly increased from 5.8 (2005–2006) to 16.3 % (2011–2012) (P < 0.01). The rate of detection of the toxic shock syndrome toxin-1 gene significantly decreased from 66.7 (2005–2006) to 51.6 % (2011–2012) (P < 0.01) whilst that of the Panton-Valentine leukocidin gene significantly increased from 0.1 (2005–2006) to 2.1 % (2011–2012) (P < 0.01). The resistance rates of cefotaxime levofloxacin clarithromycin and minocycline decreased every year. The resistance rates of these antimicrobial agents for the SCCmec type IV or V strains were significantly lower than those for the SCCmec type I or II strains (P < 0.01 respectively). Therefore these results suggest that the annual transitions of the virulence factors and antibiograms in MRSA are closely related to the increase of SCCmec type IV/V strains.
Relationship between the severity of acne vulgaris and antimicrobial resistance of bacteria isolated from acne lesions in a hospital in Japan
Propionibacterium acnes and Staphylococcus epidermidis are normal skin inhabitants that are frequently isolated from lesions caused by acne and these micro-organisms are considered to contribute to the inflammation of acne. In the present study we examined the antimicrobial susceptibilities and resistance mechanisms of P. acnes and S. epidermidis isolated from patients with acne vulgaris in a university hospital in Japan from 2009 to 2010. Additionally we analysed the relationship between the antimicrobial resistance of P. acnes and the severity of acne vulgaris. Some P. acnes strains (18.8 %; 13/69) were resistant to clindamycin. All strains had a mutation in the 23S rRNA gene except for one strain that expressed erm(X) encoding a 23S rRNA methylase. Tetracycline-resistant P. acnes strains were found to represent 4.3 % (3/69) of the strains and this resistance was caused by a mutation in the 16S rRNA gene. Furthermore three strains with reduced susceptibility to nadifloxacin (MIC = 16 µg ml−1) were detected. When analysing the correlation between the antimicrobial resistance of P. acnes and S. epidermidis more than 80 % of the patients who carried clindamycin-resistant P. acnes also carried clindamycin-resistant S. epidermidis. However no epidemic strain that exhibited antimicrobial resistance was detected in the P. acnes strains when analysed by PFGE. Therefore our results suggest that the antimicrobial resistance of P. acnes is closely related to antimicrobial therapy. Additionally those P. acnes strains tended to be frequently found in severe acne patients rather than in mild acne patients. Consequently the data support a relationship between using antimicrobial agents and the emergence of antimicrobial resistance.
Molecular epidemiology and antimicrobial susceptibilities of 273 exfoliative toxin-encoding-gene-positive Staphylococcus aureus isolates from patients with impetigo in Japan
The molecular epidemiology and antimicrobial susceptibilities of 273 Staphylococcus aureus isolates positive for the exfoliative toxin-encoding gene obtained from patients with impetigo in Japan in 2006 were studied. The mecA gene was detected in 74 meticillin-resistant S. aureus (MRSA) and 23 meticillin-susceptible S. aureus (MSSA) isolates. All isolates with the staphylococcal cassette chromosome (SCC) mec were classified into type IV (92.8 % 90/97) or V (7.2 % 7/97). The ET-encoding gene etb was found primarily in strains with mecA (87.7 % 71/81) whilst eta (86.6 % 161/186) was detected mainly in strains without mecA. The chromosomal enterotoxin-encoding gene cluster egc was found in 83.0 % of strains with eta whilst no enterotoxin-encoding gene was detected in strains with only etb. PFGE showed that each strain carrying eta etb and etd could be classified into distinct groups. The susceptibility profiles of MRSA to antimicrobial agents excluding β-lactams were similar to those of MSSA. Gentamicin- and clarithromycin-resistant strains were frequently found for both MRSA and MSSA. The aminoglycoside-resistance gene aacA–aphD was detected in 97.3 % of MRSA and 85.4 % of MSSA. Additionally the macrolide-resistance gene ermA or ermC was detected in 67.6 % of MRSA and 71.4 % of MSSA. Therefore these results suggest that SCCmec types IV or V have spread particularly in MSSA carrying etb in the community.