The Antibacterial Effect of Aqueous Thyme Extract on MDR Isolates of Different Clinical Samples
Recently, Multidrug resistant (MDR) bacteria have widely spread and increasing by time causing death. This may be because of the overuse or misuse of antibiotics. With the increase in antibiotic-resistant bacteria and the lack of new antibiotics being brought onto the market, alternative strategies need to be found to cope with infections resulting from drug-resistant bacteria. A possible solution may be to combine existing antibiotics with plant extracts or phytochemicals to enhance the efficacy of antibiotics.
The aim of this work is to estimate the effect of aqueous extract of thyme as antibacterial agent on MDR isolates and also to test its effect on the levofloxacin antibacterial activity against MDR isolates. A total of 36 isolates were collected from different clinical sources. The isolate were identified biochemically and undergone antimicrobial sensitivity. Four different commercial thyme samples were collected from different sources and each undergone microscopical examination. For each MDR isolate Minimal Inhibitory Concentration (MIC) of levofloxacin alone, thyme aqueous extract alone and then the combination of both was determined using broth microdilution test.
The results of the study revealed that 36.11% of isolates were MDR. The range of MIC of levofloxacin for MDR isolates was 15.5- >250µg/ml with the median 125µg/ml. Aqueous extract of sample 1 and 4 showed the best MIC for S.aureus and E-coli standard strains and hence their MIC was estimated against the MDR isolates. Aqueous extract of sample 1 showed MIC less than 150 mg/ml in 38.5% of MDR isolates compared to sample 4 that showed MIC less than 150 mg/ml in 53.8% of MDR isolates. MIC of levofloxacin to MDR isolates was with median 125µg/ml compared to 62.5µg/ml when was estimated in combination with aqueous extract of thyme sample 4. The thyme aqueous extract of sample 4 caused 2 fold, 4 fold, & 83.3 fold decreases (in levofloxacin MIC) 30.7%, 23.08% & 7.69% of MDR isolates respectively.