Drug resistance and Giardia

Giardiasis is a worldwide disease that can cause serious morbidity. Metronidozole is the current recommended drug for treatment, and is mostly still effective. However, Giardia duodenalis, the causative agent, is capable of developing resistance to high levels of metronidozole and other drugs, in vitro, via a number of mechanisms. Resistance, in vivo, has been reported and many cases of treatment failure have been variously attributed to a number of causes, including resistance. Here, Jacqueline and Peter Upcroft ask: is this the beginning of another chapter of drug resistance? or is the situation likely to remain as a 'few refractory cases'? Should we wait to find out or can we act positively to avert the possibility of yet another valuable drug in our limited pharmacopoeia becoming obsolete?