Letter: Treatment of giardiasis

Treatment of giardiasis: relative efficacy of metronidazole as compared with tinidazole

50 patients with giardiasis were treated with either metronidazole or tinidazole in random order according to a code. 25 patients received 2.0 g metronidazole on 2 consecutive days; 19 were cured (76%); 7 patients complained of mild side-effects. 25 patients received tinidazole 2.0 g as a single dose, and 22 were cured (88%); 5 patients complained of mild side-effects. The difference between the results of the two regimens was not statistically significant. A 1-week course of metronidazole (200 mg 3 times daily) was successful in 8/9 failures; 1 patient was finally cured with mepacrine.

Access of metronidazole into the chronically inflamed middle ear with reference to anaerobic bacterial infections

Strictly anaerobic bacteria were found in about one third of 138 consecutive cases of active chronic otitis media. These infections were always mixed involving aerobes as well. In 79 cases only aerobes were found and 16 cultures were sterile. To provide a basis for possible clinical trials, the penetration of metronidazole into the ear was studied after an oral dose of 2.4 g to patients with chronic otitis media. Significant amounts of biologically active metronidazole were found in 8 of 12 middle ear discharges at 2--4 h, the concentrations varying between 9.4 and 65.0 microgram/ml. Between 2 and 13 h after administration, significant drug concentrations all exceeding the highest reported bactericidal ones were found in the middle ear mucosa in 6 cases of the 8 in which the determinations were possible. Neither the mucosal nor the discharge concentrations correlated with the simultaneous serum levels of metronidazole, which were high in all 23 patients studied.

Comparison of four dosage schedules in the treatment of giardiasis with metronidazole

Sixty patients with parasitologically confirmed giardiasis were treated with metronidazole using four different regimens administered to four groups of 15 patients each. A seven-day course of 200 mg thrice daily successfully eliminated the organism in 11 patients. A repetition of the seven-day course after an interval of one week was successful in 14 patients, a single dose of 2400 mg in nine patients, and two 2400 mg doses on successive days in 12 patients. Late relapses, detected more than one month after therapy, were relatively common in the single-dose groups. Side-effects associated with the 2400 mg dosages were frequent but tolerable.

Giardiasis: clinical and therapeutic aspects

Malabsorption was present in 29 of 40 symptomatic patients with giardiasis. Twenty-three had impaired D-xylose absorption; in 20 vitamin B12 absorption was low, and 15 patients had steatorrhoea. More severe malabsorption was associated with more marked histological abnormalities. Metronidazole, 2-0 g as a single daily dose on three successive days, produced a parasitological cure rate of 91%. In contrast, the standard course of mepacrine, 100 mg thrice daily for 10 days, eradicated the parasite in only 63% of patients. Improvements in absorption and jejunal morphology followed anti-giardial treatment. Tetracycline in eight patients failed to eradicate the parasite, intestinal absorption was unaltered, and histological appearances of the jejunal mucosa often deteriorated.