Low prevalence of metronidazole- and clarithomycin-resistant Helicobacter pylori in the 's-Hertogenbosch region, 1998-2003

OBJECTIVE: To measure the prevalence of metronidazole- or clarithromycin-resistant Helicobacter pylori. DESIGN. Retrospective. METHOD: All positive H. pylori cultures with known susceptibility to metronidazole or clarithromycin between 1998 and 2003 were selected from the database of the Microbiology Laboratory in 's-Hertogenbosch, the Netherlands. Resistance to clarithromycin and metronidazole was determined using the E-test with cut-off minimum inhibitory concentrations of > or = 2 microg/ml and > or = 8 microg/ml, respectively. RESULTS: Of the 960 cultures with known metronidazole susceptibility, 135 (14%) were resistant. Of the 959 cultures with known clarithromycin susceptibility, 26 (3%) were resistant. The percentages of resistant cultures were higher in women than in men (17% versus 12% and 4% versus 2%, respectively). There was no relationship between age and resistance. Over the course of the study period, resistance to metronidazole decreased slightly, whereas resistance to clarithromycin increased slightly. CONCLUSION: Prevalence of metronidazole- and clarithromycin-resistant H. pylori strains in the 's-Hertogenbosch region was so low that the combination of a proton pump inhibitor, clarithromycin and amoxicillin can be used in patients with H. pylori infection without first determining susceptibility.     

幽门螺杆菌临床分离株耐药性研究

目的 分析深圳地区幽门螺杆菌临床分离株，对多种常用抗幽门螺杆菌抗生素的药敏和耐药情况。方法 采用琼脂稀释法和E-test药敏试验检测幽门螺杆菌对甲硝唑、阿莫西林和克拉霉素的药敏和耐药性。结果 MIC范围：甲硝唑0．54～＞32μg／m1；阿莫西林0．28～＞32μg／m1；克拉霉素＜0．016～1．2μg／m1；耐药情况：65％(E-test法)对甲硝唑耐药，37．5％对阿莫西林耐药，克拉霉素耐药率为0。结论 深圳地区幽门螺杆菌对甲硝唑和阿莫西林耐药率较高，而对克拉霉素无耐药现象。     

Crude ethanolic extracts of Garcinia kola seeds Heckel (Guttiferae) prolong the lag phase of Helicobacter pylori: inhibitory and bactericidal potential

Problems associated with current treatment regimens have generated a considerable interest in alternative approaches for the eradication of Helicobacter pylori infections using phytochemical compounds. In an attempt to identify potential sources of such compounds, the antimicrobial activity of five solvent extracts of Garcinia kola seeds were investigated against 30 clinical strains of H. pylori and a standard control strain, NCTC 11638, using standard microbiological techniques. Metronidazole and amoxicillin were included in these experiments as positive control antibiotics. All the extracts tested exhibited anti-H. pylori activity with zone diameters of inhibition between 0 and 25 mm. The ethanol extract demonstrated considerable anti-H. pylori activity with a percentage susceptibility of 53.3% and minimum inhibitory concentration for 50% susceptibility (MIC??) values ranging from 0.63 to 5.0 mg/mL. Ranges of MIC?? values for amoxicillin and metronidazole were 0.01-0.63 mg/mL and 0.04-5.0 mg/mL, respectively. The inhibitory activity of the ethanol extract was similar to that of metronidazole (P?>?.05) as opposed to amoxicillin (P?相似文献   

咸宁地区幽门螺杆菌临床分离株耐药性分析

目的为了解咸宁地区幽门螺杆菌(Helicobacter pylori,Hp)的耐药性状况。方法从慢性胃炎(chronic gastri-tis,CG)和慢性消化性溃疡(chronic peptic ulcer,CPU)患者的胃黏膜活检组织中分离培养出156株Hp,用Kirby–Baner药敏纸片法检测Hp对甲硝唑、替硝唑、克拉霉素、阿莫西林、四环素、呋喃唑酮、利福平的耐药率,比较不同性别、区域、胃疾病之间的耐药性。结果咸宁地区Hp对甲硝唑、替硝唑、克拉霉素、阿莫西林、四环素、呋喃唑酮、利福平的耐药率分别为65.4%、41.7%、12.2%、14.1%、0、7.0%、9.7%。不同性别、区域、胃疾病之间耐药率差异无统计学意义(P﹥0.05)。结论咸宁地区Hp对甲硝唑、替硝唑的耐药性严重;对克拉霉素、阿莫西林、呋喃唑酮、利福平的耐药率较低;未发现对四环素耐药。克拉霉素和阿莫西林为本地区根除Hp感染的首选抗菌药物。     

Inhibitory and bactericidal potential of crude acetone extracts of Combretum molle (Combretaceae) on drug-resistant strains of Helicobacter pylori

Infection with Helicobacter pylori is strongly associated with a number of gastroduodenal pathologies. Antimicrobial resistance to commonly-used drugs has generated a considerable interest in the search for novel therapeutic compounds from medicinal plants. As an ongoing effort of this search, the susceptibility of 32 clinical strains of H. pylori and a reference strain-NCTC 11,638-was evaluated against five solvent extracts of Combretum molle, a plant widely used for the treatment of gastric ulcers and other stomach-related morbidities in South Africa. The extracts were screened for activity by the agar-well diffusion method, and the most active one of them was tested against the same strains by micro-broth dilution and time kill assays. Metronidazole and amoxicillin were included in these experiments as positive control antibiotics. The solvent extracts all demonstrated anti-H. pylori activity with zone diameters of inhibition between 0 and 38 mm. The most potent anti-H. pylori activity was demonstrated by the acetone extract, to which 87.5% of the clinical strains were susceptible. The minimum inhibitory concentration (MIC90) values for this extract ranged from 1.25 to 5.0 mg/mL while those for amoxicillin and metronidazole ranged from 0.001 to 0.94 mg/mL and from 0.004 to 5.0 mg/mL respectively. The acetone extract was highly bactericidal at a concentration of 2.5 and 5.0 mg/mL, with complete elimination of the test organisms in 24 hours. Its inhibitory activity was better than that of metronidazole (p<0.05) as opposed to amoxicillin (p<0.05). The results demonstrate that C. molle may contain therapeutically-useful compounds against H. pylori, which are mostly concentrated in the acetone extract.     

兰索拉唑、克拉霉素、甲硝唑三联疗法治疗幽门螺杆菌相关性溃疡病疗效观察

目的探讨兰索拉唑、克拉霉素、甲硝唑三联疗法治疗幽门螺杆菌相关性溃疡病的效果。方法对51例确诊为幽门螺杆菌(Hp)感染的胃溃疡、十二指肠溃疡患者利用兰索拉唑、克拉霉素、甲硝唑三联疗法进行治疗,观察溃疡愈合情况及Hp根除情况。结果本疗法对溃疡的总有效率为90%,Hp根除率为88%。结论兰索拉唑、克拉霉素、甲硝唑三联疗法治疗幽门螺杆菌相关性溃疡具有药物剂量小、Hp根除率高、溃疡愈合迅速、疗程短等优点,值得在临床上推广应用。     

Failure of Helicobacter pylori eradication--suggestions for further therapy

Success of first H. pylori eradication attempts in the literature is around 80-90% and based on urea breath test of 1027 patients in Hungary is 75%. Repeated eradication attempts are needed in 10-25% of cases. In the clinical practice in Hungary second and third eradication attempts were successful only in 36% and 20% of cases. To improve efficacy the following suggestions has to be kept in mind: 1. Do not repeat the same combination if the first attempt is failed. 2. After failure of the first PPI + amoxicillin + clarithromycin triple therapy, either the quadriple therapy (PPI + tetracycline + metronidazole + bismuth) or the replacement of PPI with ranitidine bismuth citrate in the triple therapy is suggested. 3. If PPI + amoxicillin + metronidazole/tinidazole therapy fails, the metronidazole/tinidazole can be replaced by clarythromycin. 4. Do not start with clarithromycin + metronidazole/tinidazole therapy. 5. In case of uncertain previous therapies and for third eradication treatment send the patient to specialist. Rifabutin-based combinations seem to be effective, but the use of them in general practice is not advised due to the possible development of mycobacterium tuberculosis resistance.     

The new aspects of the eradication of Helicobacter pylori and the importance of bacterial resistance

The first line treatment of Helicobacter pylori infection is a 7-day PPI-based (PPI+clarithromycin+amoxycillin or metronidazole) combined therapy. Success of first eradication attempts in the literature is around 80-90%, while in Hungary 75%. Repeated eradication is needed in 10-25% of cases. The second and third line treatments are successful only in 36% and 20% of cases. Treatment failure is increasing worldwide with the higher rates of bacterial, especially clarithromycin resistance. Patients' noncompliance, pharmacogenetic and pharmacokinetic properties of the applied drugs are important as well. The eradication success rates are unacceptable in populations with higher metronidazole and clarithromycin resistance, that is why there is a need for newer combinations. A possible solution is the application of sequential therapy, or using newer antibiotics (levofloxacin). The importance of new natural substances (lactoferrin, probiotics, plant drugs) must be further investigated.     

Sources of variation of Helicobacter pylori treatment success in adults worldwide: a meta-analysis

BACKGROUND: A vast number of Helicobacter pylori treatment trials have been conducted. Regimens may vary in efficacy in different patient populations. METHODS: We identified sources of treatment effect variation from 618 treatment groups using weighted cross-classified multi-level meta-regression models. Summary effect estimates were calculated within groups that lacked identified heterogeneity. RESULTS: Overall, treatment was less successful with shorter treatment duration and dual drug (versus triple or quadruple drug) therapies. For nitroimidazole-based regimens, treatment was less successful in populations with frequent childhood H. pylori infection or metronidazole resistance and more successful in northeastern Asia. Non-nitroimidazole treatments of longer duration and those from less recent reports were most successful. Some one-week regimens--(nitroimidazole/ tetracycline/bismuth, ranitidine bismuth citrate/amoxicillin/clarithromycin, and clarithromycin/amoxicillin/proton pump inhibitor) were highly successful in northeastern Asia regardless of metronidazole resistance. The most successful regimen in populations with both a high prevalence of metrondiazole resistance and frequent infection in children (metronidazole/furazolidone/amoxicillin) eliminated fewer than 70% of infections. CONCLUSIONS: More effective treatments are needed for most populations of the world where H. pylori infection in children and drug resistance are common. Current treatment guidelines do not coincide with the best treatment regimens identified in this meta-analysis.     

Azithromycin and clarithromycin: overview and comparison with erythromycin.

Azithromycin and clarithromycin are erythromycin analogues that have recently been approved by the FDA. These drugs inhibit protein synthesis in susceptible organisms by binding to the 50S ribosomal subunit. Alteration in this binding site confers simultaneous resistance to all macrolide antibiotics. Clarithromycin is several-fold more active in vitro than erythromycin against gram-positive organisms, while azithromycin is 2- to 4-fold less potent. Azithromycin has excellent in vitro activity against H influenzae (MIC90 0.5 microgram/ml), whereas clarithromycin, although less active against H influenzae (MIC90 4.0 micrograms/ml) by standard in vitro testing, is metabolized into an active compound with twice the in vitro activity of the parent drug. Both azithromycin and clarithromycin are equivalent to standard oral therapies against respiratory tract and soft tissue infections caused by susceptible organisms, including S aureus, S pneumoniae, S pyogenes, H influenzae, and M catarrhalis. Clarithromycin is more active in vitro against the atypical respiratory pathogens (e.g., Legionella), although insufficient in vivo data are available to demonstrate a clinical difference between azithromycin and clarithromycin. Superior pharmacodynamic properties separate the new macrolides from the prototype, erythromycin. Azithromycin has a large volume of distribution, and, although serum concentrations remain low, it concentrates readily within tissues, demonstrating a tissue half-life of approximately three days. These properties allow novel dosing schemes for azithromycin, because a five-day course will provide therapeutic tissue concentrations for at least ten days. Clarithromycin has a longer serum half-life and better tissue penetration than erythromycin, allowing twice-a-day dosing for most common infections. Azithromycin pharmacokinetics permit a five-day, single daily dose regimen for respiratory tract and soft tissue infections, and a single 1 g dose of azithromycin effectively treats C trachomatis genital infections; these more convenient dosing schedules improve patient compliance. Azithromycin and clarithromycin also are active against some unexpected pathogens (e.g., B burgdorferi, T gondii, M avium complex, and M leprae). Clarithromycin, thus far, appears the most active against atypical mycobacteria, giving new hope to what has become a difficult group of infections to treat. Gastrointestinal distress, a well known and major obstacle to patient compliance with erythromycin, is relatively uncommon with the new macrolides. Further clinical data and experiences may better define and expand the role of these new macrolides in the treatment of infectious diseases.     

Increasing antimicrobial resistance of Vibrio cholerae OI biotype E1 tor strains isolated in a tertiary-care centre in India

The antimicrobial susceptibility patterns are on constant change with the recent emergence of multidrug-resistant strains of most bacteria. Results of recent studies in India showed that most isolates of Vibrio cholerae O1 were resistant to the commonly-used antibiotics. The study was conducted to determine the antibiotic susceptibility patterns of V. cholerae O1 isolated during 2008-2010 at the hospital of the Jawaharlal Nehru Institute of Post Graduate Medical Education and Research, Puducherry, India. In total, 154 strains of V. cholerae O1 from 2,658 stool specimens were reported during January 2008-December 2010--34 in 2008, 2 in 2009, and 118 in 2010. The isolates of V. cholerae O1 were subjected to antimicrobial susceptibility testing using the Kirby-Bauer method. The antibiotic disks tested were tetracycline (30 microg), furazolidone (100 microg), ampicillin (10 microg), ceftriaxone (30 microg), and ciprofloxacin (5 microg). Escherichia coli ATCC 25922 was used as the control organism. The minimum inhibitory concentrations (MICs) of ceftriaxone, ciprofloxacin, and tetracycline were determined using the agar dilution method for all the strains. The E-test method was used for the strains which had either intermediate resistance or were resistant to the antibiotics by the agar dilution method. The results of the agar dilution corroborated the results of the E-test. The MIC of ceftriaxone in 151 strains was <2 microg/mL while it was 16 microg/mL in three strains; the latter three strains were resistant to ceftriaxone by the disc-diffusion test. The MIC of ciprofloxacin in 150 strains was <0.5 microg/mL while the MIC of tetracycline was <1 microg/mL. In the remaining four strains, the MIC of tetracycline was >32 microg/mL, and the MIC of ciprofloxacin was >8 microg/mL. These four strains were resistant to both tetracycline and ciprofloxacin by the disc-diffusion test and were exclusive of the three ceftriaxone-resistant strains. The majority of the isolates were obtained from children aged 0-5 year(s)-70.3% (83 of 118) and 41.2% (14 of 34) were reported in 2010 and 2008 respectively. Since treating severe cases of cholera with antibiotics is important, the continuing spread of resistance in V. cholerae to the most important agents of therapy is a matter of concern. Also, chemoprophylaxis with antimicrobial agents is likely to become even more difficult.     

Phenotypic and Genetic Characterization of Antimicrobial Profiles of Helicobacter pylori Strains in Cuba

The study evaluated the antibiotic resistance patterns of Helicobacter pylori strains against metronidazole and clarithromycin in a hospital in Havana, Cuba. Eighty-five percent, 22.5%, and 10% of 40 H. pylori strains investigated were resistant to metronidazole, ciprofloxacin, and clarithromycin respectively but all were susceptible to amoxicillin and tetracycline. RdxA truncation was found only in metronidazole-resistant strains. In such strains, reported are eight and two novel mutations in the rdxA and frxA genes respectively. Two-point mutations in the 23S rRNA genes of clarithromycin-resistant strains were detected. A high prevalence of metronidazole resistance was found in Cuban H. pylori strains. Mutations in the rdxA gene may contribute more significantly than frxA gene to the high level of resistance to metronidazole. This study supports the need to continue monitoring the antibiotic susceptibility in H. pylori in Cuba to guide the treatment of such infection.Key words: Antibiotic resistance, Gene mutations, Helicobacter pylori, Cuba     

湖州地区幽门螺杆菌耐药情况分析

目的：调查分析浙江省湖州地区不同性别不同年龄人群中幽门螺杆菌感染及对抗生素的耐药情况。方法对湖州市中心医院2013年9月至2015年12月收集的23771份胃镜检查患者的胃黏膜样本进行幽门螺杆菌分离培养，并用平板掺入法对幽门螺杆菌进行药敏试验，对药敏的结果进行统计学分析。结果23771份胃黏膜样本中共分离培养出幽门螺杆菌菌株9106株，分离培养阳性率为38.30%，其中男性阳性率为39.72%，高于女性的36.90%，差异有统计学意义（χ2=20.046，P<0.01）。湖州地区幽门螺杆菌对克拉霉素的平均耐药率为20.60%（1876株），左氧氟沙星的平均耐药率为26.86%（2446株），甲硝唑的平均耐药率为95.43%（8690株），30岁以上人群的耐药率均呈现明显的增长，左氧氟沙星的增长幅度最大。女性人群幽门螺杆菌对克拉霉素和左氧氟沙星的耐药率分别为22.41%和30.14%，均高于男性人群，差异有统计学意义（χ2=17.029和46.285，P均<0.01）。结论本地区对克拉霉素、左氧氟沙星和甲硝唑均有非常高的耐药率，应重视菌株的分离培养和耐药性检测，治疗过程中应考虑性别和年龄的耐药性差异。     

Blood and respiratory diffusion of antibiotics. A critical analysis of predictive parameters for clinical effectiveness

The implementation of a treatment for lower respiratory tract infections must integrate a pharmacokinetic/pharmacodynamic (PK-PD) approach of antibiotic dosing. The activity of beta-lactam antibiotics is best predicted by the duration of time during which serum concentrations exceed the MIC (T>MIC). T>MIC of 30-40% is sufficient to achieve clinical cure in immunocompetent patients. This threshold is achieved with amoxicillin for penicillin susceptible or resistant Sreptococcus pneumoniae and with amoxicillin-clavulanate and ceftriaxone for S. pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis. For macrolides, the activity is best predicted by T>MIC and for azithromycin and telithromycin by area-under-the-curve/MIC (AUC/MIC). Sufficient PK-PD values are only achieved for macrolides against susceptible strains of S. pneumoniae and against M. catarrhalis; for telithromycin, an AUC/MIC>25, which is necessary for bacterial eradication, is achieved in>99% of patients for S. pneumoniae and M. catarrhalis and>90% of patients for H. influenzae. For fluoroquinolones, both peak/MIC and AUC/MIC are predictors of clinical and bacteriological efficacy. AUC/MIC required ratios vary according to pathogens and severity of diseases from 48 to 125. These thresholds are reached for respiratory pathogens; for S. pneumoniae, AUC/MIC90 ratios of levofloxacin and moxifloxacin are 96 and 192, respectively; the presence of a mutation in parC increases the risk for the acquisition of additional mutations and failure.     

Antimicrobial resistance incidence and risk factors among Helicobacter pylori-infected persons, United States

Helicobacter pylori is the primary cause of peptic ulcer disease and an etiologic agent in the development of gastric cancer. H. pylori infection is curable with regimens of multiple antimicrobial agents, and antimicrobial resistance is a leading cause of treatment failure. The Helicobacter pylori Antimicrobial Resistance Monitoring Program (HARP) is a prospective, multicenter U.S. network that tracks national incidence rates of H. pylori antimicrobial resistance. Of 347 clinical H. pylori isolates collected from December 1998 through 2002, 101 (29.1%) were resistant to one antimicrobial agent, and 17 (5%) were resistant to two or more antimicrobial agents. Eighty-seven (25.1%) isolates were resistant to metronidazole, 45 (12.9%) to clarithromycin, and 3 (0.9%) to amoxicillin. On multivariate analysis, black race was the only significant risk factor (p < 0.01, hazard ratio 2.04) for infection with a resistant H. pylori strain. Formulating pretreatment screening strategies or providing alternative therapeutic regimens for high-risk populations may be important for future clinical practice.     

Vitamin K deficiency from dietary vitamin K restriction in humans

Vitamin K is required for the maintenance of normal hemostatic function. Ten college-aged male subjects chose diets restricted in vitamin K content for 40 d. Median phylloquinone intakes based on analysis of food composites dropped from 82 micrograms/d during the prestudy period to 40 and 32 micrograms/d at d 9 and 27 of dietary restriction, respectively. Serum phylloquinone concentrations fell from a mean of 0.87 to 0.46 ng/mL during a 21-d period of vitamin K restriction. Supplementation with 50 micrograms phylloquinone/d for 12 d increased serum phylloquinone to 0.56 ng/mL, and supplementation with 500 micrograms phylloquinone/d increased serum phylloquinone to 1.66 ng/mL. Vitamin K restriction resulted in alterations in a functional clotting assay that detects undercarboxylated prothrombin species in plasma and in a decrease in urinary gamma-carboxyglutamic acid. Supplementation with either 50 or 500 micrograms of phylloquinone restored both these indices to near normal values. These data are consistent with a human dietary vitamin K requirement of approximately 1 microgram/kg body wt/d.     

胃溃疡及胃炎患者幽门螺杆菌耐药性分析

目的 了解胃溃疡及胃炎患者幽门螺杆菌(Helicobacterpylori,Hp)对甲硝唑等抗生素的耐药情况.方法 采集右江民族医学院附属医院近3年确诊为Hp感染患者的胃窦部黏膜样本进行Hp分离培养和鉴定,经鉴定后选择374株Hp菌株,采用纸片扩散法测定其对甲硝唑、阿莫西林、克拉霉素等抗生素的敏感性.结果 Hp对甲硝唑、阿莫西林、克拉霉素的耐药率从2006年的68.6%,10.2%,15.3%分别上升到2008年的91.7%,21.2%,28.8%;部分Hp同时对多种抗生素耐药,同时对甲硝唑、克拉霉素和阿莫西林耐药的有14株,耐药率为3.74%.结论 胃溃疡及胃炎患者Hp对甲硝唑、阿莫西林、克拉霉素均有一定耐药性,有必要使用其他抗生素替代.     

Eradication of Helicobacter pylori infection with proton pump inhibitor-based triple therapy. A randomised study

BACKGROUND: Helicobacter pylori (H. pylori) infection plays an important role in the pathogenesis of duodenal ulcer (DU) disease. Low DU recurrences and reinfection rates were universally described, when treatment was effective. It has been suggested that short-term triple therapy, comprising a proton pump inhibitor plus 2 antibiotics (clarithromycin, amoxycillin or a nitroimidazole), should be used as first choice in treating H. pylori infection. Nevertheless, conflicting results have been reported on using these treatment regimens in different countries. Our aim was to compare cure rates of H. pylori infection, with a 1-week triple therapy versus 10 and 15 day triple schedules, in patients with DU. METHODS: A total of 172 patients (91 males, mean age 56.2+/- 3.2 years) were randomly treated with a triple therapy including a standard dose of proton pump inhibitor, amoxicillin at a dose of 1 g twice daily and clarithromycin 500 mg twice a day. Sixty-six patients received a 1-week triple therapy (group I), 42 subjects were treated with a 10-day triple therapy (group II) and 64 others with a 14-day triple therapy (group III). H. pylori infection at entry and after eradication, at least 4 weeks after therapy had ended, were assessed by 13C urea breath test and histology on biopsies from the antrum and the corpus. RESULTS: At the end of the course of treatment, the overall H. pylori eradication rate was 68.2% (45/66) in group I, 76.2% (32/42) in group II and 71.9% (46/64) in group III, without any statistically significant difference between the 3 differing period regimens, although a trend for better results with the 10-day triple therapy was observed. Compliance was good and side effects infrequent and mild. CONCLUSIONS: None of the 3 periods of triple therapy achieved 80% eradication rate recommended by the Maastricht Consen-sus Conference. The 10-day triple therapy, although not significantly, provided a satisfactory treatment against H. pylori infection.     

Increasing spectrum in antimicrobial resistance of Shigella isolates in Bangladesh: resistance to azithromycin and ceftriaxone and decreased susceptibility to ciprofloxacin

Antimicrobial resistance of Shigella isolates in Bangladesh, during 2001-2002, was studied and compared with that of 1991-1992 to identify the changes in resistance patterns and trends. A significant increase in resistance to trimethoprim-sulphamethoxazole (from 52% to 72%, p < 0.01) and nalidixic acid (from 19% to 51%, p < 0.01) was detected. High, but unchanged, resistance to tetracycline, ampicillin, and chloramphenicol, low resistance to mecillinam (resistance 3%, intermediate 3%), and to emergence of resistance to azithromycin (resistance 16%, intermediate 62%) and ceftriaxone/cefixime (2%) were detected in 2001-2002. Of 266 recent isolates, 63% were resistant to > or =3 anti-Shigella drugs (multidrug-resistant [MDR]) compared to 52% of 369 strains (p < 0.007) in 1991-1992. Of 154 isolates tested by E-test in 2001-2002, 71% were nalidixic acid-resistant (minimum inhibitory concentration [MIC] > or =32 microg/mL) and had 10-fold higher MIC90 (0.25 microg/mL) to ciprofloxacin than that of nalidixic acid-susceptible strains exhibiting decreased ciprofloxacin susceptibility, which were detected as ciprofloxacin-susceptible and nalidixic acid-resistant by the disc-diffusion method. These strains were frequently associated with MDR traits. High modal MICs were observed to azithromycin (MIC 6 microg/mL) and nalidixic acid (MIC 128 micdrog/mL) and low to ceftriaxone (MIC 0.023 microg/mL). Conjugative R-plasmids-encoded extended-spectrum beta-lactamase was responsible for resistance to ceftriaxone/cefixime. The growing antimicrobial resistance of Shigella is worrying and mandates monitoring of resistance. Pivmecillinam or ciprofloxacin might be considered for treating shigellosis with caution.