In vitro inactivation of Mycobacterium avium subsp. paratuberculosis (MAP) by use of copper ions

Abstract

BackgroundMycobacterium avium subsp. paratuberculosis (MAP) is the causative agent of paratuberculosis, a contagious infectious disease that affects domestic and wild ruminants causing chronic inflammation of the intestine. MAP has proven to be very resistant to both physical and chemical processes, making it difficult to control this pathogen. Based on the recognized antimicrobial properties of copper, the objective of this study was to evaluate the effectiveness of copper ions to reduce MAP numbers and/or MAP viability in a fluid matrix. Besides, methicillin-resistant Staphylococcus aureus (MRSA), and Escherichia coli were used as controls of the effectiveness of copper ions. MAP-spiked PBS was subjected to copper ions treatment at 24 V for 5 min and the PBS suspensions were sampled before and after treatment. MAP viability and quantification were determined using three complementary techniques: a phage amplification assay, MGIT culture and qPCR.ResultsModerate numbers (103 CFU ml−1) of the two control bacteria were completely eliminated by treatment with copper ions. For MAP, copper ions treatment reduced both the viability and numbers of this pathogen. Phage assay information quickly showed that copper ions (24 V for 5 min) resulted in a significant reduction in viable MAP. MGIT culture results over time showed statistically significant differences in time-to-detection (TTD) values between PRE and POST treatment. MAP genome equivalent estimates for PBS suspensions indicated that MAP numbers were lower in samples POST-treatment with copper ions than PRE-treatment.ConclusionsThe use of copper ions resulted in a significant reduction of MAP in a liquid matrix, although some MAP survival on some occasions was observed.

Effectiveness of copper ions against Mycobacterium avium subsp. paratuberculosis and bacterial communities in naturally contaminated raw cow’s milk

“…The copper treatment device consisted of a 0·5 l glass beaker in which two high purity copper plates were immersed. The setup of the copper treatment apparatus was the same as reported previously (Steuer et al 2018…”

“…), before and after copper treatment. Quantification was based on a standard curve for the estimation of MAP numbers by Roche 2.0 real‐time IS 900 PCR (Steuer et al 2018…”

“…The use of copper as an antimicrobial was officially approved in 2008 by the United States Environmental Protection Agency (EPA 2008). We previously showed that copper ions can cause a significant reduction of viable MAP in a liquid matrix (phosphate‐buffered saline, PBS), although some laboratory strains of MAP‐tolerated copper ions (Steuer et al 2018…”

Attempted Control of Paratuberculosis in Dairy Calves by Only Changing The Quality of Milk Fed to Calves

“…For this reason, our group has explored an alternative to heat treatments as a means of decreasing microbial loads in raw milk. Using an in vitro model, we demonstrated that the use of copper ions results in a signi cant reduction of MAP suspended in phosphate buffered saline (PBS) [17]. Then, we observed that copper ions decreased viable MAP counts in milk similarly (Steuer et al unpublished observations).…”

“…The naturally MAP-contaminated milk was decontaminated using a copper treatment adapted from Steuer et al [17], modi ed for eld conditions. Brie y, the treatment device consisted of an aluminum receptacle containing 50 L of milk naturally contaminated with MAP in which two high purity copper cylinders were immersed.…”