The antitrichomonal activity of amidonitrothiazoles

Antitrichomonal Agents 5-Nitrothiazoles, 5-Nitropyridines and 5-Nitropyrimidines

Some 5-nitrothiazoles, 5-nitropyridines and 5-nitropyrimidines have been synthesised and evaluated against Trichomonas vaginalis and Trichomonas foetus in vitro and in vivo in the mouse, hamster and monkey. Although 2-amino-5-nitropyrimidine, 2-acetamido-5-nitropyrimidine and 2-trifluoroacetamido-5-nitropyrimidine were highly active in mice infected with T. vaginalis the activity was not superior to the standard 2-acetamido-5-nitrothiazole. The nitropyrimidines were highly species specific, being much more active in vivo against T. vaginalis than against T. foetus. One compound, 2-amino-5-nitropyrimidine was selected as the best of this series because of the high blood levels obtained after a single oral dose in a monkey, and its presence in a biologically active form

Synthesis and antiprotozoal activity of some imidazoles derivatives

The synthesis and in vitro antiprotozoal activity of a series of nitroimidazoles are described. A substituted phenyl group and, in many of the compounds, a N-substituent were also present: vinylogues of some of the compounds are described. Several of the nitroimidazoles exhibit very high in vitro activity against Trichomonas vaginalis and T. foetus, and good activity against Histomonas meleagridis and Entamoeba histolytica. Their antifungal action was lower than that of some of the un-nitrated imidazoles. The antiprotozoal activity of these compounds is discussed in relation to their chemical structure. 4-p-Acetamidophenyl-, 4-p-chlorophenyl- and 4-(3,4-dichlorophenyl)-1-methyl-5-nitroimidazole, and 4-p-chlorophenyl- and 4-(3,4-dichlorophenyl)-1-(2-hydroxyethyl)-5-nitroimidazole are the most active against Trichomonas.

Synthesis and antimicrobial evaluation of nitazoxanide-based analogues: identification of selective and broad spectrum activity

A library composed of nitazoxanide-based analogues was synthesized and assayed for increased antibacterial efficacy against the pyruvate-ferredoxin oxidoreductase (PFOR) using microorganisms Helicobacter pylori, Campylobacter jejuni and Clostridium difficile. Derivatives were found to recapitulate and improve activity against these organisms and select analogues were tested for their ability to disrupt the PFOR enzyme directly. The library was also screened for activity against staphylococci and resulted in the identification of analogues capable of inhibiting both staphylococci and all PFOR organisms at low micromolar minimum inhibitory concentrations with low toxicity to human foreskin cells.

Experimental approaches to the chemotherapy of Trichomoniasis

1. Experimental systems are described for studying the interaction of compounds with various species of trichomonad. In vitro systems have been used to study the effects of compounds on trichomonads growing in culture and to determine the speed of action of compounds on non-dividing populations. In vivo experiments have utilized vaginal infections in hamsters and subcutaneous, intraperitoneal, intra-muscular and caecal infections in mice. In vitro assays have also been carried out on serum and urine obtained from non-infected rats or monkeys dosed with compounds showing in vitro activity.

2. The types of activity which can be obtained experimentally are illustrated by reference to a number of local remedies already available and to representatives of a number of chemical types, notably acridines, quinoxaline N-oxides, anthrapyrimidines, nitrofurans, thiazoles, imidazoles and pyrazoles.

We thank Dr R. F. Jennison and Mr H. Francis for clinical trial results, Drs J. K. Landquist, G. V. McHattie and D. Richardson for synthesis of some of the compounds mentioned, Dr G. E. Paget for toxicity data, Dr W. M. Duncan for data on the metabolism of 5667, Dr J. M. Pryce for pK determinations and Mrs M. Ryley, P. Ward, A. Fletcher, D. Wood and Miss V. Rowe for technical assistance at various stages in the work.

Laboratory studies with the systemic trichomonacide, metronidazole

Laboratory studies with the trichomonacidal agent, metronidazole, show that 66 strains of T. vaginalis were killed in three days by concentrations of 0.0625 mug./ml. to 1 mug./ml. Estimations of serum and urine levels in nine volunteers, the serum levels in 31 women, and the urine levels in 33 women show that metronidazole is rapidly absorbed and excreted in high concentration in the urine. Development of resistance to metronidazole by T. vaginalis has not been demonstrated either in vivo or in vitro. No toxic effect was demonstrated in the blood, liver, or kidney.

Practical problems of diagnosing trichomoniasis in women

Analysis of eight groups of data collected at varying intervals during a period of seven years showed fluctuations in the sensitivity of tests to diagnose trichomoniasis in women. The best results were obtained from fresh, correctly prepared Diamond's medium, Feinberg-Whittington's medium, and modified Squires and McFadzean's medium (which showed 82% to 94% relative sensitivity). Poor results were identified consistently in commercially prepared Bushby medium from one source (40% relative sensitivity) and in a batch of commercially prepared Squires and McFadzean's medium from which chloramphenicol had been omitted (23% relative sensitivity). Examination of wet film, culture, and exfoliative cytology stained by Papanicolaou's method were shown to be indispensable for auditing the performance of each test and to maintain the quality of a diagnostic service.

Anaerobes and Gardnerella vaginalis in non-specific vaginitis

Clinical evidence of bacterial vaginosis was present in 25 (35%) of 72 patients attending a London venereology clinic and correlated significantly with abnormal organic acids in vaginal secretions (24/25), with Gardnerella vaginalis on culture (17/25), with complaints of vaginal malodour (15/25), and with a relative scarcity of white blood cells in vaginal secretions. Anaerobic vaginal flora were presumptively identified by gas-liquid chromatographic analysis of organic acids found in vaginal secretions. The clinical criteria used to diagnose bacterial vaginosis included the presence of at least three of the four following characteristics: (a) a vaginal pH greater than or equal to 4.5, vaginal secretions that (b) were homogeneous, (c) contained "clue" cells, and (d) released a "fishy" amine odour when mixed with 10% potassium hydroxide. Because 17 of the 25 patients with clinical bacterial vaginosis had both chromatographic bacterial vaginosis and G vaginalis, causative organisms were difficult to identify. None of the six patients who had G vaginalis but not chromatographic bacterial vaginosis had clinical bacterial vaginosis, but seven of the 10 women with chromatographic bacterial vaginosis but not G vaginalis had clinical bacterial vaginosis (p less than 0.02, chi 2 with Yates's correction). This finding supports the recent suggestions that anaerobes are important in the production of clinical signs of bacterial vaginosis.

Growth of Candida species in liquid culture medium for Trichomonas vaginalis

The growth of Candida spp from vaginal specimens in Bushby's liquid medium for T vaginalis was compared with that on Sabouraud's agar medium, and isolation was significantly greater in Bushby's medium (p less than 0.001). Isolations missed (4.43%) in Bushby's medium probably represented vaginal carriage of small numbers of Candida spp.

Urine culture for the detection of Trichomonas vaginalis in men

Urine samples were collected from 248 men, 21 of whom were known contacts of women infected with Trichomonas vaginalis. This organism was cultured from only three of the 21 specimens from patients in the contact group. The cultural technique was shown to be capable of reliably detecting small numbers of organisms under practical conditions; it appears, therefore, that most male contacts shed relatively few trichomonads and that the infective dose for women must be correspondingly small.

Abnormal forms of Trichomonas vaginalis

Abnormal forms of Trichomonas vaginalis have been demonstrated by both conventional and scanning electron microscopy after inoculation of media with clinical material from cases of trichomonal vaginitis. Twenty-six cases of vaginitis have been studied; 10 of them showed the abnormal forms of trichomonads after growth in a modification of the medium described by Bushby and Copp (1955), while 16 showed only normal forms.

Sensitivity of Trichomonas vaginalis to metronidazole, tinidazole, and nifuratel in vitro

Prompted by the sensitivity of trichomonads to metronidazole and nifuratel in clinical practice, a study was conducted in 1971-1972 of 63 consecutive strains of Trichomonas vaginalis isolated from women with clinically refractory vaginal discharge. Their susceptibility to metronidazole, tinidazole, and nifuratel was tested, using a serial tube dilution technique. The minimum concentrations which in 48 hrs caused immobilization and lysis of trichomonads cultured in Diamond's medium was assessed. No differences in drug potency could be determined. The median trichomonistatic and trichomonicidal concentrations were 0-1 and 0-6 mug/ml. respectively when using an inoculum of 10,000 organisms per ml. An inoculum of 100,000 per ml. resulted in inhibitory concentrations of 1-0 and killing concentrations of 3-3 mug./ml. These levels are readily attained in blood and vaginal tissue after oral ingestion of the two imidazole derivatives. Thus, metronidazole has maintained its efficacy since it was first introduced more than a decade ago. The few therapeutic failures with metronidazole and tinidazole are considered to have been caused by pharmacokinetic deficiencies in the patients, or by re-infection.

Review of current methods for the detection of Trichomonas in clinical material

Methods of ;wet preparation', stained films, and culture were used to detect trichomonads in vaginal exudate and the results of these methods are compared. A method using a wet preparation and Oxoid no. 2 Trichomonas medium is reliable for routine use.