IMPACT OF TEA TREE OIL ON BIOFILM FORMATION AND SWARMING MOTILITY BY MDR PROTEUS MIRABILIS

Abstract

Emergence of multi-drug resistant isolates of P. mirabilis and development of new resistant microbial phenotypes are growing and the outlook for the use of antimicrobial drugs in the future is still uncertain. Therefore, there is an increased demand for developing alternative strategies to conventional antibiotic therapy and to continue studies to develop new drugs, either synthetic or natural. In this study, 25 isolates of P. mirabilis were isolated from different clinical samples collected from different departments of Tanta University hospitals. All isolates were resistant to amoxicillin, azithromycin and tetracycline. A high incidence of resistance was also recorded for cefprozil (96%) and cefotaxime (80%). P. mirabilis isolates were moderately resistant to imipenem (64%), lomefloxacin (64%), ampicillin (60%), cefepime (60%) and ciprofloxacin (52%). However, the lowest incidence of resistance was recorded for amikacin (8%). All isolates showed MAR indices >0.2 and exhibited MDR profile. The antimicrobial activity of tea tree oil was evaluated using agar dilution method recording MIC50 value of 12.8 mg/ml. The effect of tea tree oil on the strong biofilm producer isolates with relatively wide swarming zone diameters was evaluated. Results obtained showed that tea tree oil (1/4 and 1/2 MIC) presented significant and dose-dependent inhibition in the biofilm production by the tested isolates of P. mirabilis by ≥50%. In addition, tea tree oil inhibited the swarming motility of P. mirabilis isolates in a dose-dependent manner. Therefore, tea tree oil could act as a potential source of alternative antimicrobials or as antipathogenic compound against MDR P.mirabilis.