Umlano, Norin Grace T. <br/><br/>
Antibacterial efficacy of combined leaf and root extract of pink periwinkle (catharanthus roseus (l.) g.don) against escherichia coli, staphylococcus aureus and methicillin – resistant staphylococcus aureus in vitro/ 
Norin Grace T. Umlano 
 - Bayombong:  Nueva Vizcaya State University,  2018. 
 - xv, 54 leaves :  illustrations, photos ;  28 cm. 
<br/><br/> The study compared the in-vitro antibacterial efficacy of combined pink periwinkle (Catharanthus roseus) leaf and root ethanol extract with the commercially available antibiotics (gentamicin, penicillin and trimethoprim-sulfamethoxazole) and identified the most effective concentration capable of inhibiting the growth of Escherichia coli, Staphylococcus aureus and methicillin-resistant Staphylococcus aureus (MRSA). The study was carried out using standard procedure. The extraction was achieved using mortar and pestle and blender with 95% ethanol as solvent. Water bath was used to get pure extract of the plant. The study was laid out in a completely randomized design (CRD) with the following treatments Treatment 1 (positive control) gentamicin, penicillin and trimethoprim-sulfamethoxazole, Treatment 2-75% combined pink periwinkle leaf and root extract, Treatment 3- 50% combined pink periwinkle leaf and root extract: Treatment 4-23% combined pink periwinkle leaf and root extract; Treatment 5 (negative control) -distilled water and Treatment 6 (negative control) ethanol. Each treatment was replicated three times.<br/>Based on the results of the study, the ethanol extract of combined leaf and root of pink periwinkle is not effective as antibacterial against Staphylococcus aureus in comparison to penicillin. The combined pink periwinkle leaf and root ethanol extract exhibited a moderate activity at 75% concentration at 12 hours of incubation but has a lower efficacy compared to gentamicin as an antibacterial against Escherichia coli. The ethanol extract of combined leaf and root of pink periwinkle showed moderate activity against methicillin-resistant Staphylococcus aureus (MRSA) and can be used as an alternative to trimethoprim-sulfamethoxazole.<br/>  Thesis (Doctor of Veterinary Medicine) 
<br/><br/>includes appendices and bibliographical references.