Clinical and Pharmacological Evaluation of Pistacia atlantica Nut Extract on Septic Arthritis Caused by Staphylococcus aureus: An Experimental Study

Background: Today, the incidence of septic arthritis by Staphylococcus aureus has increased due to intra-articular injections, prosthetic joints, and underlying conditions such as rheumatoid arthritis and immunosuppression. Pistacia atlantica has significant antioxidant, anti-inflammatory, and antibacterial activities. Objectives: Considering S. aureus as the most important etiology of septic arthritis, this experimental study aimed to evaluate the effects of P. atlantica on septic arthritis. Methods: Septic arthritis was induced by intra-articular injection of S. aureus suspension in left stifles of rats, which were divided randomly into eight groups, containing ten per group, including normal: no intervention; control: septic arthritis was induced but not treated; Oral Placebo (OP): 14 days daily P.O.; Local Injected Placebo (LIP): a single dose intra-articular (IA injection) of normal saline; Oral P. atlantica (OPa): 14 days daily P.O. P. atlantica extract; Local Injected P.atlantica (LIPa): a single-dose IA injection of P. atlantica extract; Prophylactic Oral P. atlantica (ProOPa): prophylactic P.O. P. atlantica extract daily one week before the induction for 21 days; Prophylactic Local Injected P. atlantica (ProLIPa): a prophylactic single-dose IA injection of P. atlantica extract one week before the induction. For further evaluations, blood and histopathological samples were obtained. Results: Pistacia atlantica oral medication reduced the physical symptoms of inflammation. Although hematological analysis showed a fall in the control group compared to the normal group, all medicated groups increased. The OPa group showed the closest WBC count (9.46 ± 4.12 × 109/L) to the normal group (P = 0.073). All histopathological parameters had significantly higher scores in the control group compared to the normal group. Although the scores increased in the groups that received P. atlantica, they decreased in the groups that received placebo, except for synovitis degree. The OPa group demonstrated a lower degree of synovitis (1.40± 0.51) than the control group; however, it was not significant (P = 0.690). Local injections revealed higher erosion scores (2.80 ± 0.63 for the LIPa group and 2.70 ± 0.48 for the ProLIPa group) than the control group (P < 0.05). Conclusions: Oral administration of P. atlantica alleviated the clinical symptoms. Cellular immunity activation and systemic benefits of oral P. atlantica were assessed. Histopathology confirmed the immune system involvement and antibacterial activity of P. atlantica. More erosion may be due to more bacterial debris with arthritogenic properties. Meanwhile, the probability of the stimulatory effect of P. atlantica extract for synovial content should not be ignored.