Survival of the ovine footrot pathogen Dichelobacter nodosus in different soils

• Published in: Anaerobe Vol. 38; pp. 81 - 87
• Main Authors: Muzafar, Mohd, Green, Laura E., Calvo-Bado, Leo A., Tichauer, Esther, King, Hayley, James, Philip, Wellington, Elizabeth M.H.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.04.2016
• Subjects: Animals; Anti-Infective Agents - pharmacology; Azides - pharmacology; Dichelobacter nodosus; Dichelobacter nodosus - classification; Dichelobacter nodosus - isolation & purification; Dichelobacter nodosus - physiology; Disease reservoirs; DNA, Bacterial; Foot Rot - microbiology; Footrot; Microbial Viability; Ovine foot disease; Pathogen survival; Propidium - analogs & derivatives; Propidium - pharmacology; Sheep; Sheep Diseases - microbiology; Soil Microbiology; Dichelobacter nodosus; Pathogen survival; Footrot; Disease reservoirs; Ovine foot disease
• ISSN: 1075-9964; 1095-8274
• DOI: 10.1016/j.anaerobe.2015.12.010

Dichelobacter nodosus (D. nodosus) is the causative agent of footrot in sheep; one of the most important health and welfare issues of sheep worldwide. For control programmes to be effective, it is essential that the transmission cycle of D. nodosus is understood and bacterial reservoirs in the environment are better defined. This study evaluated the survival of D. nodosus in different soils using soil microcosms. Cultivation independent and dependent methods were used to detect D. nodosus over 40 days from seeding in soil. A D. nodosus specific probe was used for quantification by qPCR and viability was assessed by cell permeability to an intercalating dye, PMA, and by culture. Survival varied dramatically depending on soil type, matric potential (MP) and temperature. Our findings indicate that D. nodosus survival was higher at 5 °C compared with 25 °C in all soils and significantly longer at both temperatures in clay soil (>44% clay) compared with other soil types. Survival under all conditions was longer than 30 days for both culture independent and dependent methods, this is substantially longer than previous studies and, if this is an infectious dose, longer than the current recommendation of resting a field for 14 days to prevent onward infection. •Viable Dichelobacter nodosus was detected for 40 days off host in ventilated soil microcosms.•D. nodosus survival rate was affected by matric potential, temperature and soil type.•D. nodosus survived for 40 days both at 5 °C and 25 °C in four contrasting soils.•D. nodosus survival was higher at 5 °C compared with 25 °C in all soils.•D. nodosus survival was significantly longer in clay soil (>44% clay).