Min Park

Antibiotic resistance in Helicobacter pylori strains and its effect on H. pylori eradication rates in a single center in Korea.

Background Clarithromycin, amoxicillin, metronidazole, tetracycline, and levofloxacin have been commonly used for the eradication of Helicobacter pylori. We compared the change in antibiotic resistance of H. pylori strains during two separate periods and investigated the effect of antibiotic resistance on H. pylori eradication. Methods H. pylori strains were isolated from 71 patients between 2009 and 2010 and from 94 patients between 2011 and 2012. The distribution of minimal inhibitory concentration (MIC) of 5 antibiotics was assessed using the agar dilution method, and H. pylori eradication based on the antimicrobial susceptibility of the isolates was investigated retrospectively. Results Antibiotic resistance rate against clarithromycin, amoxicillin, tetracycline, metronidazole, and levofloxacin for the 2009-2010 isolates were 7.0% (5/71), 2.8% (2/71), 0% (0/71), 45.1% (32/71), and 26.8% (19/71), respectively, and for the 2011-2012 isolates were 16.0% (15/94), 2.1% (2/94), 0% (0/94), 56.3% (53/94), and 22.3% (21/94), respectively. Multi-drug resistance for 2 or more antibiotics increased slightly from 16.9% (12/71) in the 2009-2010 isolates to 23.4% (22/94) in the 2011-2012 isolates. In follow-up testing of 66 patients, first-line treatment successfully eradicated H. pylori in 50 patients (75.8%) and failed in 4 of 7 patients (57.1%) in a clarithromycin-resistant and amoxicillin-susceptible group. Conclusions We observed an increase in resistance to clarithromycin and an overall increase in multi-drug resistance during the 2 study periods. The effectiveness of the eradication regimen was low with combinations of clarithromycin and amoxicillin, particularly in the clarithromycin-resistant group. Thus, eradication of H. pylori depends upon periodic monitoring of antimicrobial susceptibility.

Inhibitory effects of anthocyanins on secretion of Helicobacter pylori CagA and VacA toxins

Anthocyanins have been studied as potential antimicrobial agents against Helicobacter pylori. We investigated whether the biosynthesis and secretion of cytotoxin-associated protein A (CagA) and vacuolating cytotoxin A (VacA) could be suppressed by anthocyanin treatment in vitro. H. pylori reference strain 60190 (CagA+/VacA+) was used in this study to investigate the inhibitory effects of anthocyanins; cyanidin 3-O-glucoside (C3G), peonidin 3-O-glucoside (Peo3G), pelargonidin 3-O-glucoside (Pel3G), and malvidin 3-O-glucoside (M3G) on expression and secretion of H. pylori toxins. Anthocyanins were added to bacterial cultures and Western blotting was used to determine secretion of CagA and VacA. Among them, we found that C3G inhibited secretion of CagA and VacA resulting in intracellular accumulation of CagA and VacA. C3G had no effect on cagA and vacA expression but suppressed secA transcription. As SecA is involved in translocation of bacterial proteins, the down-regulation of secA expression by C3G offers a mechanistic explanation for the inhibition of toxin secretion. To our knowledge, this is the first report suggesting that C3G inhibits secretion of the H. pylori toxins CagA and VacA via suppression of secA transcription.

Cyanidin 3-O-Glucoside Reduces Helicobacter pylori VacA-Induced Cell Death of Gastric KATO III Cells through Inhibition of the SecA Pathway

Two key virulence factors of Helicobacter pylori are the secreted virulent proteins of vacuolating toxin A (VacA) and cytotoxin associated protein A (CagA) which lead to damages of gastric epithelial cells. We previously identified that the cyanidin 3-O-glucoside (C3G) inhibits the secretion of both VacA and CagA. In the current report, we show that C3G inhibits VacA secretion in a dose-dependent manner by inhibiting secretion system subunit protein A (SecA) synthesis. As SecA is involved in translocation of bacterial proteins, we predicted that inhibition of the SecA pathway by C3G should decrease H. pylori-induced cell death. To test this hypothesis, the human gastric cell line KATO III cells were co-cultured with H. pylori 60190 (VacA+/CagA+) and C3G. We found that C3G treatment caused a decrease in activation of the pro-apoptotic proteins caspase-3/-8 in H. pylori-infected cells leading to a decrease in cell death. Our data suggest that consumption of foods containing anthocyanin may be beneficial in reducing cell damage due to H. pylori infection.

Prevalence of multidrug-resistant Acinetobacter baumannii producing OXA-23-like from a healthcare facility of Gangwon Province, South Korea

Acinetobacter baumannii is an increasingly important nosoomial pathogen, frequently causing nosocomial outbreaks in ospital Intensive Care Units. Infections caused by multidrugesistant (MDR) bacteria occur worldwide. Furthermore, A. aumannii strains resistant to all antimicrobial agents tested, usceptible only to colistin, are referred to as extensively drugesistant strains and have been detected in South Korea [1]. The purpose of this study was to determine the genetic basis nd molecular epidemiology of MDR A. baumannii isolates and to etermine the clonal relationship amongst A. baumannii clinical solates obtained from Gangwon Province, South Korea. The various olecular determinants of A. baumannii, including carbapenem, ephalosporin, aminoglycoside and quinolone resistance, were nvestigated in this study. Eighty-six strains of non-duplicate A. baumannii were identied by MicroScan WalkAway-96 (Dade Behring, Sacramento, CA) s belonging to Acinetobacter baumannii/haemolyticus from the uniersity hospital laboratory in Gangwon Province from July 2007 to uly 2010. Genomic identification was performed using the amplied ribosomal DNA restriction analysis (ARDRA) method [2]. The xperimental results revealed that all strains tested were A. bauannii. Minimum inhibitory concentrations of clinical antimicrobials or all isolates were determined by the MicroScan WalkAway-96 I system and were interpreted according to Clinical and Laboatory Standards Institute (CLSI) document M100-S19. All of the solates showed resistance to ampicillin, cefazolin, cefotaxime, efotetan, ceftazidime, ceftriaxone, cefuroxime, ciprofloxacin, eropenem, moxifloxacin and ticarcillin/clavulanic acid. Morever, most of A. baumannii isolates showed resistance to cefepime, entamicin, trimethoprim/sulfamethoxazole, tobramycin, aztrenam, amikacin, imipenem and ampicillin/sulbactam. To analyse the production of class B and D carbapenemases, A. aumannii isolates were first screened by a modified Hodge test 3]. All of the A. baumannii isolates showed positive results in the odified Hodge test and negative results in the ethylene diamine etra-acetic acid (EDTA) disk synergy test, indicating the production f class D or another type of carbapenemase. The -lactamases and resistance determinants were detected y multiplex polymerase chain reaction (PCR) [4]. The presence f insertion sequence ISAba1 inserted upstream of blaOXA-23-like nd blaOXA-51-like was sought via PCR using combinations of the SAba1 primers and the OXA-23-like and OXA-51-like reverse rimers [4]. All of the isolates possessed the encoded gene or an intrinsic OXA-51-like carbapenemase and an acquired XA-23-like carbapenemase. ISAba1 inserted upstream of laOXA-23-like was identified in all of the A. baumannii isolates. [ ntimicrobial Agents 39 (2012) 448– 454

In vitro and in vivo anti-Helicobacter pylori activities of FEMY-R7 composed of fucoidan and evening primrose extract

[This corrects the article on p. 28 in vol. 30, PMID: 24707302.].

Regulatory Effects of Black Rice Extract on Helicobacter pylori Infection-Induced Apoptosis

SCOPE Black rice extract (BRE) contains cyanidin 3-O-glucoside (C3G), an anthocyanin, as the major component. In this study, we found that BRE inhibits the mRNA and protein expression of genes encoding cytotoxin-associated protein A (cagA) and vacuolating protein A (vacA) in Helicobacter pylori 60190 strain. METHODS AND RESULTS We performed RT-PCR and western blotting to show that BRE inhibits the mRNA and protein expression of SecA. Because SecA is involved in VacA export in bacteria, our result suggests a positive correlation between BRE-induced inhibition of secA expression and VacA secretion. Further, we perform MTT assay and flow cytometry to show that BRE decreases the apoptosis of H. pylori-infected KATO III cells. Finally, we perform western blotting to show that the cell-protective effect of BRE is associated with decreased levels of active proapoptotic proteins caspases and PARP and increased levels of antiapoptotic proteins survivin and XIAP in H. pylori-infected cells. CONCLUSION Thus, our results indicate that BRE acts as a potent inhibitor of the biogenesis of H. pylori virulence proteins and decreases the apoptosis of H. pylori-infected cells. Moreover, our results suggest that BRE can be used to exert beneficial effects in patients with gastroduodenal diseases caused by H. pylori.