The Toxicity and Antibacterial Effects of Povidone-Iodine Irrigation in Fracture Surgery

Abstract

Objective: Surgical site infection is a common complication of surgery, especially in orthopedics. Povidone-Iodine (PI) is one of the oldest and most commonly used disinfectants in surgery. However, the toxicity and antimicrobial effect of PI have not been discussed. In addition, no study has explored the optimum PI concentration for sterilization and tissue healing. This study explores the germicidal efficacy of different concentrations PI, in addition, the toxicity and antibacterial effects of PI irrigation in fracture surgery are also discussed.

Methods: Methicillin-resistant Staphylococcus aureus and Pseudomonas aeruginosa (P. aeruginosa) were used to evaluate the germicidal efficacy of PI in vitro and in vivo. In vitro, the effects of PI on bacterial growth were analyzed. 2.5%, 1.25%, 0.5%, 0.25%, 0.05%, 0.025%, 0.005%, 0.0025% and 0% PI was added into the bacterial suspension, besides, the bacterial algebra and growth rate were tested. Meanwhile, the fluorescence intensity of viable bacteria was also tested to evaluate the effects of PI on bacterial survival. In vivo, first, femoral fracture with wound infection rat models were established. Second, thyroid gland sections, blood thyroxine, urinary iodine, wound local skin, muscle and bone tissue sections, serum creatinine and alanine aminotransferase, serum and bone local tissue interleukin-6 (IL-6), interleukin-10 (IL-10), bone morphogenetic protein (BMP-2), vascular endothelial growth factor (VEGF) and transforming growth factor (TGF-β1) were detected in rat femoral shaft fracture model with 5%, 2.5%, 0.5%, 0.05%, and 0% PI irrigation. Third, tissue bacteria culture was tested in rat femoral fracture with wound infection model with different concentrations PI irrigation.

Results: In vitro, 2.5%, 1.25%, 0.5% PI inhibited the growth of bacteria. 1.25%, 0.5% PI killed all the bacteria, while 0.25%, 0.05% PI had not killed bacteria after about 10 min. The iodine absorption of 5%, 2.5%, 0.5% PI irrigation did not cause thyroid injury. The 5%, 2.5%, 0.5% PI irrigation did not make serum creatinine and alanine aminotransferase abnormal and can remove bacteria from wounds. The 0.5%, 2.5% PI irrigation can promote tissue healing and increase BMP-2, VEGF, TGF-β1, IL-10, in addition, decrease IL-6. 5% PI irrigation would inhibit tissue healing, and increase IL-6, decrease BMP-2, VEGF, TGF-β1, IL-10.

Conclusions: Povidone-Iodine was a widely used disinfectant and 2.5%, 1.25% and 0.5% PI could effectively kill bacteria. Five percent and lower concentration PI irrigation was safe and could not cause thyroid, kidney and liver damage. The 0.5% PI irrigation was beneficial for tissue healing but 5% PI irrigation was the opposite.

Keywords: Antibacterial properties; MRSA; Povidone-iodine irrigation; Pseudomonas aeruginosa; Toxicity of povidone-iodine.

Fig. 1

Kidney section in some groups, which shows that the kidney was not damaged. (A) 5% PI group at 7 days; (B) 0.5% PI group at 7 days; (C) 5% PI group at 28 days; (D) 0.5% PI group at 28 days.

Fig. 2

Seven days after femoral fracture irrigated by PI. The healing of skin and muscle tissue are shown. The wound in 5% PI group is red and swollen with necrotic tissue in the muscle tissue. The skin of 0.5% PI group, 0% PI group and group F healed well without redness and swelling and no necrosis of muscle tissue is observed.

Fig. 3

X‐ray lateral position of fracture in each group. It can be seen that the fracture line of 5% PI group is still clear at 4 weeks, while the callus amount of 2.5% PI group and 0.5% PI group at 2 weeks is significantly more than other groups.

Fig. 4

X‐ray anteroposterior position of fracture in each group. The results are the same as in the lateral position.

Fig. 5

Immunohistochemical staining images. The 0.5% and 2.5% PI irrigation increased TGF‐β1, IL10 expression and decreased IL6 expression, as compared with the 0% PI group at 14 days. The 5% PI irrigation had the opposite effects. Images ×100; original scale bar, 200 μm.

Fig. 6

Cytokines in serum and bone tissue of rats in each group. BMP‐2, VEGF, TGF‐β1 and IL‐10 of 5% PI group are lower than other groups, while IL‐6 is higher than other groups at 1 and 2 weeks. BMP‐2, VEGF, TGF‐β1 and IL‐10 of 2.5% PI group and 0.5 PI group are higher than other groups, while IL‐6 is lower than other groups at 1 and 2 weeks. *p < 0.05. (A) Serum BMP‐2; (B) serum VEGF; (C) serum TGF‐β1; (D) serum IL‐10; (E) serum IL‐6; (F) bone tissue BMP‐2; (G) bone tissue VEGF; (H) bone tissue TGF‐β1; (I) bone tissue IL‐10; (J) bone tissue IL‐6.