Abstract

A. A. Al Sahli and W. M. Abdulkhair

This study plays an important role in solution of beta-lactam resistance problem. This aim has been achieved by clavulanic acid production as beta-lactamase inhibitor. Beta-lactam-resistant Pseudomonas aeruginosa possesses beta-lactams resistance machinery by secretion of extracellular beta-lactamase enzyme. The present study was begun with collection of eighty nosocomial bacterial isolates from Riyadh hospitals through one year. Nosocomial bacterial isolates were treated by amoxicillin (250 µg ml-1 ) to determine resistant isolates. Among them fifty amoxicillin-resistant isolates could be found with different minimum inhibitory concentrations (MICs). However, one isolate considers the most potent which has MIC over than 1000 µg ml-1 and also was identified by using polymerase chain reaction (PCR) technique as P. aeruginosa. Isolated gene of P. aeruginosa has 870 bp. The second phase of this study was begun with collection of six plants which are growing in Saudi Arabia, then were identified by professionals of Science College herbarium, King Saud University. These plants were extracted by methanol and then dried. These plants are Rhazya stricta, Calotropois procera, Maerua crassifolia, Haloxylon salicornicum, Rumex vesicarius L. and Lycium shawii. The plant extracts were tested to detect and determine their antagonistic effect for amoxicillin-resistant P. aeruginosa and of course for its beta-lactamase enzyme. Only one extract of R. vesicarius L. has antagonistic effect for beta-lactamase enzyme. Beta-lactamase inhibitor was purified and characterized as clavulanic acid by using nuclear magnetic resonance (NMR) spectroscopy analysis, infra-red (IR) spectroscopy analysis and elemental analysis. Eventually, amoxicillin-resistant P. aeruginosa was inhibited by amoxicillinclavulanic acid combination at 125 µg ml-1 and 128 mg ml-1 , respectively