Effect of temperature on storage of ethionamide during susceptibility testing

Abstract

Objective: Ethionamide being thermolabile in nature, effect of temperature on the drug and its stability in liquid and solid media during susceptibility testing procedures was assessed to understand the inconsistency in DST formats.Methods: Working solution of ethionamide and Lowenstein-Jensen (LJ) media incorporated with ethionamide were preincubated at 4°C and 37°C prior to DST methods was incubated till 4 weeks at different temperatures and utilized for DST in MGIT 960.Results: Degradation of ethionamide working solution was observed at 37°C after 3 weeks of incubation. Ethionamide incorporated LJ media can be stored without compromise on susceptibility up to 5 weeks. But, a week of prior incubation at 37°C has deleterious effect on the DST profile. Ethionamide was found to degrade at 37°C after different time points when stored as solution or as LJ media. Bulgular: Ethionamide çalışma solusyonunda 37°C'de 3 haftalık inkübasyonun ardından bozunma olduğu gözlenmiştir. Ethionamide LJ ortamında beş haftaya kadar etkinliğinde bozulma olmadan saklanabilir. Fakat 37°C de bir hafta daha bekletilmesi ilaç duyarlılık profiline zararlı etkili olabilir. Ethionamide 37°C bekletilmesiyle farklı zaman aralıklarında sıvı ya da LJ ortamında bekletilmesiyle etkinliğinde değişmeler olduğu saptandı. ConclusionSonuç: DST ortamında ethionamide için iki haftaya kadar olan testlerin değerlendirilmesi önerilir.

Revisiting the susceptibility testing of Mycobacterium tuberculosis to ethionamide in solid culture medium

“…When testing drugs like ethionamide, thermolabile nature of the drug should also be considered. Being thermolabile, there could be loss or complete deterioration during inspissation and with prolonged incubation while performing different DST procedures 12 .…”