Plasmid-mediated Multidrug Resistance (MDR) has serious implications for the empiric therapy against pathogenic bacteria. Twelve (12) bacteria isolates were identified and selected based on the ability to grow on Luria-Bertani (LB) agar medium containing 100µg/ml ampicillin. The isolates tagged; U01, U02, U03, U04, U08, U10 and U11 were from urine specimens, S05, S06, S07 and S12 from stool, while B09 was from blood. The isolates were screened for Multidrug Resistant pattern according to Kirby-Bauer disc diffusion method. Plasmid DNA from the isolates was quantified and molecular weight estimated. Conjugation and transformation experiments was carried out using the MDR isolates as donors and E. coli K12 DH5α as reciepient. Most of the isolates (83.3%) were multidrug resistant. The isolates (100%) were resistant to Ampicillin, Cephalothin, Erythromycin, Fusidic acid, Novobiocin and Oxacillin. Nine isolates (75%) are sensitive and three (25%) are resistant to Augmentin. But all the isolates are sensitive to Colistin sulphate and Imipenem. The plasmid analysis revealed that all the isolates had a highest plasmid of above 10kb. Three isolates possessed single sized plasmids, while nine (9) had multiple plasmids with different sizes ranging from 1.3kb to above 10kb. A plasmid size of 2.0 and 2.8kb was detected in two isolates with similar MDR pattern, but differ in resistance to Augmentin and Gentamycin. However, the remaining plasmid sizes was distributed across isolates with the same MDR, despite the diversity of the isolates sources. Conjugation occurs with eight donor isolates, where four of the receipients (02, 05, 07 and 09 acquired highest plasmid size of 4.0kb, while S12 had 1.0kb, which indicated that, small amount of plasmid was transferred. High efficiency was found in competent cells produced using transformation buffer I and II (1.1 × 107), which confirmed the sensitivity of supercompetent cells in the uptake of plasmid DNA. This study also observed the role of plasmid as a MDR determinant that can be transferred to avirulent strains.
Keywords: Multidrug resistance, Plasmid, Conjugation, Transformation, Supercompetent cells