Witch hazel significantly improves the efficacy of commercially available teat dips

Authors: Rasooly, Reuven; MOLNAR, ADEL - Framingham State College; Do, Paula; MARRONI, GIANLUCA - Polytechnic University Of Marche; BRESCINI, LUCIA - Polytechnic University Of Marche; CIRIONI, OSCAR - Polytechnic University Of Marche; GIAVOMETTI, ANDREA - Polytechnic University Of Marche; APOSTOLIDIS, EMMANOUIL - Framingham State College

Submitted to: Pathogens
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/28/2020
Publication Date: 2/1/2020
Citation: Rasooly, R., Molnar, A., Do, P.M., Marroni, G., Brescini, L., Cirioni, O., Giavometti, A., Apostolidis, E. 2020. Witch hazel significantly improves the efficacy of commercially available teat dips. Pathogens. 9(2). Article 92. https://doi.org/10.3390/pathogens9020092.
DOI: https://doi.org/10.3390/pathogens9020092

Interpretive Summary: Mastitis is the most common and costly disease of dairy cattle worldwide, costing the U.S. dairy industry up to $2 billion annually (11% of total U.S. milk production). To prevent such infections, teat dipping in germacides is recommended, but the problem persists. Alternative teat dipping solutions (DIP, containing iodine or chlorhexidine) is thus needed. Staphylococcus aureus is one of the most frequent causes of subclinical and clinical bovine mastitis in the US, and its herd prevalence ranges from 5-50%. These bacteria cause disease by forming biofilms, which are very resistant to conventional treatment, and by producing toxins, which help the bacteria survive in the host. whISOBAX (WH) is a plant witch hazel extract that contains high levels of hamamelitannin, a phenolic compound that inhibits both biofilm formation and toxin production. We show here that the antibacterial activity of DIP against free living (planktonic) and biofilm staphylococci significantly increases when combined with WH, and thus have potential in eradicating staphylococcal infections both in acute (planktonic-associated) and in chronic (biofilm-associated) conditions. DIP and WH were also shown to be effective against the growth of Pseudomonas aeruginosa and Escherichia coli, which are gram-negative bacteria known to be associated with intramammary infections. These results suggest that the combination of the two products is advantageous in combating IMIs caused by different bacterial species.

Technical Abstract: Bovine intramammary infections (IMIs) are the main cause of economic loss in milk production. Antibiotics are often ineffective to treat infections. This is due to antimicrobial resistance and due to formation of bacterial biofilms that further enhance bacterial survival and persistence. Teat dipping containing germicides is recommended to prevent new IMIs and improve udder health and milk quality. Many different products with various active ingredients are available for teat dipping. Nevertheless, mastitis is still an ongoing battle on dairy farms, and alternative methods to prevent IMIs are needed. IMIs are often caused by staphylococci, which are gram-positive bacteria that become pathogenic by forming biofilms and producing toxins. Therefore, experiments described here were carried out on a S. epidermidis strain that readily forms a biofilm, and a S. aureus strain that produces high levels of enterotoxin A (SEA). As a model for a teat dip (DIP), BacStop iodine-based teat dip (DIP) was used. Witch hazel extract (whISOBAX (WH)) was tested because it contains a high concentration of the anti-biofilm/anti-toxin phenolic compound hamamelitannin. Using in vitro microdilution and biofilm assays we show that the minimal inhibitory or bactericidal concentrations of DIP against planktonic S. epidermidis cells increased up to 160 fold in the presence of whISOBAX. We also show that DIP is 10-fold less effective against biofilm cells, but in the presence of WH, bacterial load is reduced 1000 fold. Additionally, we show here that both DIP and WH are effective in inhibiting the growth of S. aureus, but only WH inhibits toxin production (tested for SEA). Put together, these results suggest that the antibacterial activity of DIP combined with WH is significantly higher, and thus have potential in eradicating staphylococcal infections both in acute (planktonic-associated) and in chronic (biofilm-associated) conditions. To ensure that the inhibitory effect is not limited to staphylococci, DIP and WH were tested against the growth of Pseudomonas aeruginosa and Escherichia coli, which are gram-negative bacteria known to be associated with IMIs. Results indicate that when DIP and WH were combined, their inhibitory effect increased up to 16 fold. These results suggest that the combination of the two products is advantageous in combating IMIs caused by different bacterial species.