A total of 22 microorganisms consisting of 12 bacteria and 10 fungi were used in this study (Table 1 and 3). All of the microorganisms were obtained from the microbiology laboratory of the Institute of Bioscience, University Putra Malaysia. Bacteria, other than ATCC strains, were identified by the use of biochemical profiles according to the recommendations of the manual of clinical microbiology [15 ] while fungi, other than ATCC strains, were identified depending on the macro- and micro- scopic features [16 ]. The tested bacteria and fungi were maintained on nutrient agar (Merck, Darmstadt, Germany) and sabouraud dextrose agar slants (Merck, Darmstadt, Germany), respectively, at 4°C until further use.
The tested bacteria were subjected to a panel of antibiotic susceptibility discs (BBL, USA) for profiling their antibiotic sensitivity. Out of 12 tested bacteria, three multiple drug resistant (MDR) bacteria were found. The MDR bacteria were MRSA, P. aeruginosa, and Enterohemorrhagic (EHEC) E. coli O157:H7 which were highly resistant to more than four antibiotics. Isolates other than MDR and ATCC strains were either resistant to one antibiotic or not resistant to any of the tested antibiotics. MRSA isolate was completely resistant to oxacillin, erythromycin, streptomycin, clindamycin and tetracycline. Moreover, the MRSA isolate was a bit borderline resistant to vancomycin, namely vancomycin-intermediate Staphylococcus aureus (VISA). The MDR P. aeruginosa isolate was resistant to ceftazidime, ciprofloxacin, cefepime, imipenem, and piperacillin/tazobactam. The MDR E. coli O157:H7 isolate was resistant to ampicillin, kanamycin, sulfisoxazole, and tetracycline. Therefore, nine non-MDR and three MDR bacteria were used to test the antibacterial effect of red cabbage leaves extract.