In vitro antimicrobial activity evaluation of selected medicinal plants against multidrug- resistant isolate of Clinical Bovine Mastitis

Background: Mastitis is one of the challenges impairing the development of the dairy industry. Among mastitis-causing bacteria, S. aureus and E. coli represent the main causative agents that threaten the farmers not only due to the high incidence rate and zoonotic potential but also due to reports of multi-drug resistance. The study was conducted to assess the antimicrobial activity of selected medicinal plants against multidrug-resistant bacterial isolates from clinical bovine mastitis. Milk samples from mastitis cases were aseptically collected and S. aureus and E .coli isolates were identified, the antibiotic sensitivity test pattern of the isolate were confirmed. Four medicinal plants were collected; extracted and their in vitro effectiveness on multidrug-resistant S. aureus and E. coli isolates of bovine mastitis was validated compared to the conventionally used antimicrobial drugs. Results Crude extracts from the four plants were effective against both susceptible and resistant isolates. Extract of Crotona macrostachis at 100mg/mL MIC showed the highest mean zone of inhibition (20.2 ± 1.48) on E. coli while Prunes Africana at 50mg/mL MIC showed 12.9 ± 0.74. The highest mean zone of inhibition 13.8 ± 0.84 for Datura Stamonium at a MIC of 100mg/mL and lowest mean zone of inhibition 11.64 ± 0.86 for Crotona macrostachis at 100mg/mL MIC was observed on S. aureus . Moreover, compared to S. aureus , better efficacy was observed for all tested plant extracts against E. coli. Conclusion This study indicated that traditional medicinal plant preparations might be considered as an alternative option for the treatment of resistant isolates of clinical bovine mastitis.