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Efficacy of Three-Week Oxytetracycline or Rifampin Monotherapy Compared with a Combination Regimen against the Filarial Nematode Onchocerca ochengi

Bah, G. S., Ward, E. L., Srivastava, Abhishek, Trees, Alexander J., Tanya, V. N. and Makepeace, Benjamin (2014) 'Efficacy of Three-Week Oxytetracycline or Rifampin Monotherapy Compared with a Combination Regimen against the Filarial Nematode Onchocerca ochengi'. Antimicrobial Agents and Chemotherapy, Vol 58, Issue 2, pp. 801-810.

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Onchocerciasis (river blindness), caused by the filarial nematode Onchocerca volvulus, is a major cause of visual impairment and dermatitis in sub-Saharan Africa. As O. volvulus contains an obligatory bacterial symbiont (Wolbachia), it is susceptible to antibiotic chemotherapy, although current regimens are considered too prolonged for community-level control programs. The aim of this study was to compare the efficacies of oxytetracycline and rifampin, administered separately or in combination, against a close relative of O. volvulus (Onchocerca ochengi) in cattle. Six animals per group were treated with continuous or intermittent oxytetracycline regimens, and effects on adult worm viability, dermal microfilarial loads, and Wolbachia density in worm tissues were assessed. Subsequently, the efficacies of 3-week regimens of oxytetracycline and rifampin alone and a combination regimen were compared, and rifampin levels in plasma and skin were quantified. A 6-month regimen of oxytetracycline with monthly dosing was strongly adulticidal, while 3-week and 6-week regimens exhibited weaker adulticidal effects. However, all three regimens achieved >2-log reductions in microfilarial load. In contrast, rifampin monotherapy and oxytetracycline-rifampin duotherapy failed to induce substantive reductions in either adult worm burden or microfilarial load, although a borderline effect on Wolbachia density was observed following duotherapy. Dermal rifampin levels were maintained above the MIC for >24 h after a single intravenous dose. We conclude that oxytetracycline-rifampin duotherapy is less efficacious against O. ochengi than oxytetracycline alone. Further studies will be required to determine whether rifampin reduces oxytetracycline bioavailability in this system, as suggested by human studies using other tetracycline-rifampin combinations.

Item Type: Article
Subjects: QX Parasitology > Helminths. Annelida > QX 203 Nematoda
WA Public Health > Preventive Medicine > WA 110 Prevention and control of communicable diseases. Transmission of infectious diseases
WC Communicable Diseases > Tropical and Parasitic Diseases > WC 885 Onchocerciasis
Faculty: Department: Biological Sciences > Department of Tropical Disease Biology
Digital Object Identifer (DOI):
Depositing User: Lynn Roberts-Maloney
Date Deposited: 07 May 2015 14:54
Last Modified: 06 Feb 2018 13:09


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