Genetic variation of resistant Staphylococcus aureus isolates and their susceptibility to the antimicrobial activity of some plant and algal extracts

Abstract

This study aimed to determine the antibacterial properties of different plant species and some volatile oils, and study genetic variation of  some infectious microbial isolates.

Materials and methods: A total of 32 bacterial clinical specimens were randomly collected from thirty-two patients (22 Males and 10  Females) attending the outpatient clinic of the Dermatology and Venereology of Tanta University Hospitals, Egypt. Staphylococcus aureus isolates were identified biochemically, their antibiotic susceptibility was assessed using fifteen selected antibiotic discs using the disc  diffusion method to detect the multi-drug resistant (MDR) isolates. The agar well diffusion method was used to screen the resistant S.  aureus isolates for susceptibility to the investigated natural extracts. The most effective extract was identified by calculating its minimum  inhibitory concentration (MIC). The most effective natural extracts were chemically characterized using GCMS and FT-IR analysis. SDS- PAGE was performed to evaluate genetic variation among MDR S. aureus isolates.

Key results: Nine isolates were selected among 32  bacterial isolates and identified as MDR S. aureus isolates and the isolate No. 9 was proved to be the most MDR one, recording 53%  resistance. Chebulic, safsaf willow, Jania, and Nile's roses were the most effective natural inhibitors with inhibition zone diameters of  29.67, 26, 30 and 24.67 mm, respectively. 2-Pentanone, 4-hydroxy-4-methyl-2- pentanone was the most common component in all extracts  with a presence rate of 90.87, 85.90 and 85.61% for safsaf willow, Nile's roses and Jania, respectively. MIC was 25 mg/ml for the  three selected extracts against the nine S. aureus isolates. Twenty-one bands were detected among the nine Staphylococcus aureus  isolates, only six bands appear commonly in all S. aureus isolates.