Increased Prevalence of Minocycline-Resistant Staphylococcus epidermidis with tet(M) by Tetracycline Use for Acne Treatment.

Staphylococcus epidermidis, a major skin bacterium, can cause opportunistic infections. Use of antimicrobial agents against Cutibacterium acnes for acne treatment becomes a risk factor for emergence of antimicrobial-resistant skin bacteria. In this study, the impact of antimicrobial treatment of acne vulgaris on S. epidermidis antimicrobial resistance was assessed. A total of 344 S. epidermidis strains isolated from patients with acne vulgaris who visited hospital (165 strains) and dermatological clinics (179 strains), respectively, were analyzed. Except for doxycycline, the resistance rates were higher in strains isolated from patients who had used antimicrobials for acne treatment than in those isolated from patients who had not used antimicrobials. The prevalence rates of strains with erm(C) from patients who used macrolides and clindamycin (hospital, 78.0%; clinics, 61.3%) and those of strains with tet(M) from patients who used tetracyclines (hospital, 27.5%; clinics, 42.4%) were significantly higher than those of strains from patients who did not use antimicrobials (p < 0.05). All strains with erm(A) (8/8) and 91.7% strains with erm(C) (156/170) showed high-level resistance to macrolides and clindamycin (MIC ≥256 µg/mL). Furthermore, almost all strains with tet(M) showed resistance to minocycline. Our results showed that the use of antimicrobials for acne treatment may lead to an increased prevalence of antimicrobial-resistant S. epidermidis. In particular, the emergence of minocycline-resistant strains with tet(M) owing to the use of tetracyclines (doxycycline and minocycline) is a critical issue. Appropriate antimicrobial use for acne treatment may be an important strategy to prevent the emergence of antimicrobial-resistant skin bacteria.

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 .

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.

Antimicrobial activity and additive effect of the modified Gingyo-san with antimicrobials against Helicobacter pylori.

INTRODUCTION: Helicobacter pylori is an important factor in the development of gastroduodenal ulcers and gastric cancer. Although H. pylori eradication therapy has been employed, the eradication rate has decreased in recent years owing to an increase in clarithromycin-resistant strains. We previously reported the anti-infective effect of herbal medicines against several bacterial species. Here, we evaluated the growth inhibitory activity of herbal medicines alone and in combination with antimicrobials against H. pylori. METHODS AND RESULTS: Nine of 37 herbal medicines inhibited the growth of H. pylori ATCC700392. In particular, modified Gingyo-san showed the strongest growth inhibitory activity with a minimum inhibitory concentration (MIC) of 512 µg/ml for not only ATCC700392 but also clarithromycin-resistant strains having a 23 S rRNA mutation. Results of Time-Kill Kinetics Assay showed that 1 mg/mL modified Gingyo-san treatment for one hour killed 50% of the H. pylori population. Furthermore, modified Gingyo-san showed additive effects with clarithromycin, amoxicillin, and metronidazole against H. pylori ATCC700392 and clarithromycin-resistant strains. CONCLUSIONS: Our findings showed that modified Gingyo-san inhibits the growth of H. pylori and improves antimicrobial susceptibility when used in combination. Therefore, modified Gingyo-san has the potential to enhance the eradication rate of clarithromycin-resistant H. pylori.

Kampo medicines suppress the production of exfoliative toxins causing impetigo in Staphylococcus aureus.

An alternative approach, such as antivirulence therapy that modulates the production of bacterial toxins or virulence factors, is necessary to tackle the emergence of antimicrobial-resistant strains. Here, we investigated the potential antivirulence effects of seven Kampo medicines (Jumihaidokuto, Eppikajutsuto, Jizusoippo, Shomakakkonto, Sammotsuogonto, Hainosankyuto and Inchinkoto) against exfoliative toxin (ET)-positive Staphylococcus aureus, which is the major causative agent of impetigo. A growth inhibition assay showed that all of the selected Kampo medicines inhibited the growth of S. aureus at 1/5 (2.5 mg/mL) or less of the conventionally used concentrations. Among these, Jizusoippo and Inchinkoto (0.25-1 mg/mL) suppressed the production of ET without inhibiting the bacterial growth. Furthermore, Jizusoippo and Inchinkoto significantly suppressed the expression of ET genes in a concentration-dependent manner. Our findings strongly suggest, for the first time, that Kampo medicines, especially Jizusoippo and Inchinkoto, have the potential to serve as antivirulence agents against skin infections caused by S. aureus by suppressing the production of ET.

Tokiinshi, a traditional Japanese medicine (Kampo), suppresses Panton-Valentine leukocidin production in the methicillin-resistant Staphylococcus aureus USA300 clone.

It is necessary to develop agents other than antimicrobials for the treatment of Staphylococcus aureus infections to prevent the emergence of antimicrobial-resistant strains. Particularly, anti-virulence agents against the Panton-Valentine leukocidin (PVL)-positive methicillin-resistant S. aureus (MRSA), USA300 clone, is desired due to its high pathogenicity. Here, we investigated the potential anti-virulence effect of Tokiinshi, which is a traditional Japanese medicine (Kampo) used for skin diseases, against the USA300 clone. A growth inhibition assay showed that a conventional dose (20 mg/ml) of Tokiinshi has bactericidal effects against the clinical USA300 clones. Notably, the growth inhibition effects of Tokiinshi against S. epidermidis strains, which are the major constituents of the skin microbiome, was a bacteriostatic effect. The data suggested that Tokiinshi is unlikely to affect skin flora of S. epidermidis. Furthermore, PVL production and the expression of its gene were significantly suppressed in the USA300 clone by a lower concentration (5 mg/ml) of Tokiinshi. This did not affect the number of viable bacteria. Moreover, Tokiinshi significantly suppressed the expression of the agrA gene, which regulates PVL gene expression. For the first time, our findings strongly suggest that Tokiinshi has the potential to attenuate the virulence of the USA300 clone by suppressing PVL production via agrA gene suppression.

Clonal change of methicillin-resistant Staphylococcus aureus isolated from patients with impetigo in Kagawa, Japan.

Recently, the USA300 clone, which is a Panton-Valentine leukocidin (PVL)-positive clonal complex 8-staphylococcal cassette chromosome mec type IV (CC8-IV) community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) strain, emerged in community and hospital settings in Japan. Hence, clonal types of CA-MRSA strains are predicted to be changing. Nonetheless, long-term surveillance of CA-MRSA has not been conducted in Japan. Here, we investigated the transition and current status of CA-MRSA strains isolated from outpatients with impetigo; the samples were collected between 2007 and 2016 in Kagawa, Japan. The detection rate (22.8%, 488/2139 strains) of MRSA slightly decreased in these 10 years. Molecular epidemiological analyses showed that the prevalence of the CC89-II clone, which is a typical CA-MRSA genotype of causative agents of impetigo, significantly decreased from 48.0% (48/100 strains) in 2007-2009 to 21.9% (16/73 strains) in 2013-2016. By contrast, a non-USA300 CC8-IV clone, which is a highly pathogenic CA-MRSA/J clone, significantly increased in prevalence from 9.0% (9/100 strains) to 32.9% (24/73 strains). The prevalence of PVL-positive CA-MRSA strains increased annually from 2012 (0%) to 2015 (6.7%), whereas only one of these strains turned out to be the USA300 clone. Antibiotic susceptibility data revealed that the rates of resistance to gentamicin and clindamycin among CA-MRSA strains decreased along with the decreased prevalence of the CC89-II clone and increased prevalence of the CA-MRSA/J clone. Our data strongly suggest that the clonal types and antibiotic susceptibility of CA-MRSA isolated from patients with impetigo dramatically changed during the last 10 years in Japan.

Antibiotic That Inhibits the ATPase Activity of an ATP-Binding Cassette Transporter by Binding to a Remote Extracellular Site.

Antibiotic-resistant strains of Staphylococcus aureus pose a major threat to human health and there is an ongoing need for new antibiotics to treat resistant infections. In a high throughput screen (HTS) of 230 000 small molecules designed to identify bioactive wall teichoic acid (WTA) inhibitors, we identified one hit, which was expanded through chemical synthesis into a small panel of potent compounds. We showed that these compounds target TarG, the transmembrane component of the two-component ATP-binding cassette (ABC) transporter TarGH, which exports WTA precursors to the cell surface for attachment to peptidoglycan. We purified, for the first time, a WTA transporter and have reconstituted ATPase activity in proteoliposomes. We showed that this new compound series inhibits TarH-catalyzed ATP hydrolysis even though the binding site maps to TarG near the opposite side of the membrane. These are the first ABC transporter inhibitors shown to block ATPase activity by binding to the transmembrane domain. The compounds have potential as therapeutic agents to treat S. aureus infections, and purification of the transmembrane transporter will enable further development.

The modified Gingyo-san, a Chinese herbal medicine, has direct antibacterial effects against respiratory pathogens.

BACKGROUND: Modified Gingyo-san (MGS) is empirically used to treat various respiratory infections. MGS has been reported to have antiinflammatory and antiviral activities; however, it is not known if it has an antibacterial activity. Therefore, in this study, we aimed to investigate the antimicrobial activity of MGS against respiratory pathogens. METHODS: MGS, which is sold as an over-the-counter drug in Japan, was used for the study. Antimicrobial activity was evaluated using the disk diffusion method. Growth inhibitory activity was evaluated by measuring colony-forming units of the pathogens in the presence of MGS. RESULTS: MGS inhibited the growth of Bacillus subtilis, Streptococcus pneumoniae, and Streptococcus pyogenes, which are gram-positive bacteria. Although the growth of most gram-negative bacteria was not inhibited by MGS, interestingly, the growth of Haemophilus influenzae was inhibited. MGS did not show any activity against Candida albicans or bacteriophage φX174. CONCLUSIONS: In addition to the antiinflammatory and antiviral activities of MGS, which have already been reported, the data obtained from this study indicates that MGS has an antibacterial activity.