Activity of disulfiram (bis(diethylthiocarbamoyl)disulphide) and ditiocarb (diethyldithiocarbamate) against metronidazole-sensitive and -resistant Trichomonas vaginalis and Tritrichomonas foetus.
Clinical resistance of Trichomonas vaginalis to metronidazole is best correlated with MIC values measured under aerobic conditions. Under these conditions both disulfiram (bis(diethylthiocarbamoyl)disulphide), and its first mammalian metabolite, ditiocarb (diethyldithiocarbamate), showed high levels of activity against metronidazole-sensitive (disulfiram MIC, 0.1-0.7 microM; ditiocarb MIC, 0.3-9 microM) and -resistant (MICs 0.2-1.3 microM and 1.2-9 microM respectively) isolates. Tritrichomonas foetus was also sensitive-the MICs for seven metronidazole-sensitive isolates were 0.1-1.0 microM for disulfiram and 1.0-6.9 microM for ditiocarb; those for two highly metronidazole-resistant strains were 0.3-1.3 microM and 0.6-6 microM respectively. Under anerobic conditions most strains became highly resistant to both compounds. Surprisingly, disulfiram was consistently more active than ditiocarb. (+info)
Intestinal blockage by carcinoma and Blastocystis hominis infection.
We detected heavy infections of Blastocystis hominis in four individuals with intestinal obstruction due to cancerous growths. After surgery, the infections spontaneously resolved, without specific chemotherapy. It appears that the B. hominis infection was coincidental and not related to the neoplastic growth. We suggest that intestinal obstruction and concomitant stool retention, plus hemorrhage from cancerous lesions, may have permitted the more abundant growth of B. hominis. This is the first report of a possible relationship between intestinal obstruction and a concomitant B. hominis infection. (+info)
A new method for assessing metronidazole susceptibility of Giardia lamblia trophozoites.
A quantitative, simple, and rapid assay has been developed to assess Giardia lamblia trophozoite sensitivity to metronidazole [1-(2-hydroxyetyl)-2-methyl-5-nitroimidazole] (MTZ). This new assay utilizes the ability of live (surviving) trophozoites to take up oxygen after have been exposed to MTZ. The effect of MTZ on oxygen uptake was compared with its effect on viability as evaluated by a culture method and morphological assays. Oxygen uptake rates decreased in trophozoites treated with MTZ, and this effect was drug concentration dependent: O(2) uptake rates went from 3.04 microM O(2) min(-1) per 10(6) cells to 0.72 microM O(2) min(-1) per 10(6) cells with increasing drug concentration (0.15 to 0.6 mM) in the preincubation. Concentrations of the drug which inhibited oxygen uptake by 28 to 76% in trophozoites killed from 39 to 82% of trophozoites, as evaluated by the culture method, and altered the morphology of 21 to 86% of the trophozoites. Thus, the trophozoites killed by MTZ are nonmotile cells and do not take up oxygen. A good correlation was found between the inhibitory effects of MTZ, as evaluated by oxygen uptake, and cellular viability. Similar 50% inhibitory concentrations were obtained: 0.33 mM by oxygen uptake, 0. 26 mM by the culture method, and 0.35 mM by morphological criteria. Oxygen uptake appears to be a good indicator of parasite viability. Therefore, this new method can provide a convenient means to assess MTZ susceptibility in G. lamblia and can be applied for screening potential antigiardial agents. (+info)
Resistance of Trichomonas vaginalis to metronidazole: report of the first three cases from Finland and optimization of in vitro susceptibility testing under various oxygen concentrations.
Trichomonas vaginalis is a globally common sexually transmitted human parasite. Many strains of T. vaginalis from around the world have been described to be resistant to the current drug of choice, metronidazole. However, only a few cases of metronidazole resistance have been reported from Europe. The resistant strains cause prolonged infections which are difficult to treat. T. vaginalis infection also increases the risk for human immunodeficiency virus transmission. We present a practical method for determining the resistance of T. vaginalis to 5-nitroimidazoles. The suggested method was developed by determining the MICs and minimal lethal concentrations (MLCs) of metronidazole and ornidazole for T. vaginalis under various aerobic and anaerobic conditions. Using this assay we have found the first three metronidazole-resistant strains from Finland, although the origin of at least one of the strains seems to be Russia. Analysis of the patient-derived and previously characterized isolates showed that metronidazole-resistant strains were also resistant to ornidazole, and MLCs for all strains tested correlated well with the MICs. The suggested MICs of metronidazole for differentiation of sensitive and resistant isolates are >75 microg/ml in an aerobic 24-h assay and >15 microg/ml in an anaerobic 48-h assay. (+info)
A new highly effective short-term therapy schedule for Helicobacter pylori eradication.
BACKGROUND: Although triple therapy regimens suggested in the Current European guidelines give fairly good results, several studies have reported an unsatisfactory Helicobacter pylori eradication rate (< 80%). AIM: To evaluate the efficacy of a new short-term treatment sequence on H. pylori eradication. METHODS: A total of 52 patients with H. pylori infection and either non-ulcer dyspepsia (34 patients) or peptic ulcer (18 patients) were enrolled to receive a 10-day therapy: omeprazole 20 mg b.d. plus amoxycillin 1 g b.d. for the first 5 days, followed by omeprazole 20 mg b.d., clarithromycin 500 mg b.d. and tinidazole 500 mg b.d. for the remaining 5 days. H. pylori infection at entry was assessed by rapid urease test and histology on biopsies from the antrum and the corpus. Bacterial eradication was assessed by endoscopy (peptic ulcer patients) or 13C urea breath test (non-ulcer dyspepsia patients) 4-6 weeks after therapy had ended. RESULTS: All patients completed the study. H. pylori eradication was achieved in all but one patient, with an eradication rate of 98% (95% CI: 94.3-100) with intention-to-treat analysis. Patient compliance was good (consumption of prescribed drugs > 95%) for all but one patient, who took the triple therapy regimen for 4 days instead of 5 days. No major side-effects were reported but three (6%) patients complained of mild side-effects. CONCLUSIONS: The use of this 'five plus five' therapy schedule as an initial treatment for H. pylori deserves further investigation. (+info)
The effectiveness of omeprazole, clarithromycin and tinidazole in eradicating Helicobacter pylori in a community screen and treat programme. Leeds Help Study Group.
INTRODUCTION: Helicobacter pylori screening and treatment has been proposed as a cost-effective method of preventing gastric cancer. AIM: To assess, in a randomized controlled trial, the efficacy of therapy in eradicating H. pylori as part of a screening programme, and to report the adverse events associated with this strategy. METHODS: Subjects between the ages of 40-49 years were randomly selected from the lists of 36 primary care centres. Participants attended their local practice and H. pylori status was determined by 13C-urea breath test. Infected subjects were randomized to receive omeprazole 20 mg b.d., clarithromycin 250 mg b.d. and tinidazole 500 mg b.d. for 7 days (OCT) or identical placebos. Eradication was determined by a 13C-urea breath test 6 months and 2 years after the first visit. Successful eradication was defined as two negative 13C-urea breath tests or one negative and one missing test. Adverse events and compliance were assessed at the 6-month visit. RESULTS: A total of 32 929 subjects were invited to attend, 8407 were evaluable, and 2329 (28%) of these were H. pylori-positive. A total of 1161 subjects were randomized to OCT and 1163 to placebo; over 80% returned for a repeat 13C-urea breath test on at least one occasion. The eradication rates in those allocated to OCT were as follows: intention-to-treat, 710 out of 1161 (61%; 95% confidence interval: 58-64%); evaluable 710 out of 967 (73%; 95% CI: 71-76%); took all medication 645 out of 769 (84%; 95% CI: 81-87%). Adverse events occurred in 45% of the treatment group and in 18% of the placebo group (relative risk 2.5; 95% CI: 2.1-2.9). Compliance, male gender, no antibiotic prescription in the subsequent 2 years and experiencing a bitter taste with the medication were independently associated with treatment success. CONCLUSIONS: The OCT regimen has an eradication rate of 61% in intention-to-treat analysis and is therefore less successful in treating H. pylori as part of a screening programme compared with hospital studies in dyspeptic patients. (+info)
Cytopathogenic effect of Trichomonas vaginalis on human vaginal epithelial cells cultured in vitro.
In this study we established human vaginal epithelial cells (hVECs) in culture and evaluated their interaction with Trichomonas vaginalis parasites to complement previous studies using other cell types. Primary cultures of hVECs were established. Contaminating fibroblasts were separated from epithelial cells by differential trypsinization. Specific antibody staining revealed that over 92% of cells in hVEC monolayers were epithelial cells. T. vaginalis adhered to hVECs and produced severe cytotoxic effects resulting in obliteration of the monolayer within 24 h. Adherence and cytotoxicity were not observed when T. vaginalis was exposed to human vaginal fibroblasts or bovine vaginal epithelial cells. Likewise, the bovine parasite Tritrichomonas foetus had no cytotoxic effects on hVECs. We concluded that the interaction between T. vaginalis and hVECs is both cell specific (limited to epithelial cells and not vaginal fibroblasts) and species specific (limited to human vaginal cells and not bovine cells). Pretreatment of T. vaginalis with metronidazole or periodate abolished the adhesion of parasites to cell monolayers and the cytotoxic effect, suggesting involvement of carbohydrate-containing molecules in these processes. Different clinical isolates of T. vaginalis caused damage to cultured cells at different rates. Parasites separated from the vaginal cell monolayer by a permeable membrane did not produce a cytopathic effect, suggesting contact-dependent cytotoxicity. (+info)
Molecular epidemiology of metronidazole resistance in a population of Trichomonas vaginalis clinical isolates.
Trichomonas vaginalis, the causative agent for human trichomoniasis, is a problematic sexually transmitted disease mainly in women, where it may be asymptomatic or cause severe vaginitis and cervicitis. Despite its high prevalence, the genetic variability and drug resistance characteristics of this organism are poorly understood. To address these issues, genetic analyses were performed on 109 clinical isolates using three approaches. First, two internal transcribed spacer (ITS) regions flanking the 5.8S subunit of the ribosomal DNA gene were sequenced. The only variation was a point mutation at nucleotide position 66 of the ITS1 region found in 16 isolates (14.7%). Second, the presence of a 5.5-kb double-stranded RNA T. vaginalis virus (TVV) was assessed. TVV was detected in 55 isolates (50%). Finally, a phylogenetic analysis was performed based on random amplified polymorphic DNA data. The resulting phylogeny indicated at least two distinct lineages that correlate with the presence of TVV. A band-sharing index indicating relatedness was created for different groups of isolates. It demonstrated that isolates harboring the virus are significantly more closely related to each other than to the rest of the population, and it indicated a high level of relatedness among isolates with in vitro metronidazole resistance. This finding is consistent with the hypothesis that drug resistance to T. vaginalis resulted from a single or very few mutational events. Permutation tests and nonparametric analyses showed associations between metronidazole resistance and phylogeny, the ITS mutation, and TVV presence. These results suggest the existence of genetic markers with clinical implications for T. vaginalis infections. (+info)