Evaluating the use of antibiotic prophylaxis during open reduction and internal fixation surgery in patients at low risk of surgical site infection.

BACKGROUND: Widespread overuse and inappropriate use of antibiotics contribute to increasingly antibiotic-resistant pathogens and higher health care costs. It is not clear whether routine antibiotic prophylaxis can reduce the rate of surgical site infection (SSI) in low-risk patients undergoing orthopaedic surgery. We designed a simple scorecard to grade SSI risk factors and determined whether routine antibiotic prophylaxis affects SSI occurrence during open reduction and internal fixation (ORIF) orthopaedic surgeries in trauma patients at low risk of developing SSI. METHODS: The SSI risk scorecard (possible total points ranged from 5 to 25) was designed to take into account a patient's general health status, the primary cause of fractures, surgical site tissue condition or wound class, types of devices implanted, and surgical duration. Patients with a low SSI risk score (≤8 points) who were undergoing clean ORIF surgery were divided into control (routine antibiotic treatment, cefuroxime) and evaluation (no antibiotic treatment) groups and followed up for 13-17 months after surgery. RESULTS: The infection rate was much higher in patients with high SSI risk scores (≥9 points) than in patients with low risk scores assigned to the control group (10.7% vs. 2.2%, P<0.0001). SSI occurred in 11 of 499 patients in the control group and in 13 of 534 patients in the evaluation group during the follow-up period of 13-17 months. The SSI occurrence rate did not differ significantly (2.2% vs. 2.4%, P=0.97) between the control and evaluation groups. CONCLUSIONS: Routine antibiotic prophylaxis does not significantly decrease the rate of SSI in ORIF surgical patients with a low risk score. Implementation of this scoring system could guide the rational use of perioperative antibiotics and ultimately reduce antibiotic resistance, health care costs, and adverse reactions to antibiotics.

Degradation of antibiotic amoxicillin using 1 x 1 molecular sieve-structured manganese oxide.

The kinetics and mechanism ofamoxicillin (AMO) degradation using a 1 x 1 molecular sieve-structured manganese oxide (MnO2) was studied. The presence of the buffer solution (i.e., NaHCO3, NaH2PO4 and KH2PO4) diminished AMO binding to MnO2, thus reducing AMO degradation in the pretest; therefore, all other experiments in this study were conducted without the addition of a buffer. Third-order rate constants, second-order on AMO and first-order on MnO2 increased with elevating pH level (2.81-7.23) from 0.54 to 9.17 M(-2) s(-1), and it decreased to 4.27 M(-2) s(-1) at pH 8.53 beyond the pk(a2) of AMO (7.3). The dissolution of the MnO2 suspension with and without AMO exhibited a similar trend; that is, Mn2+ concentration increased with decreasing pH. However, the dissolution of MnO2 with AMO was greater than that without AMO, except for the reaction occurring at pH 8.53, partially indicating that MnO2 acts as an oxidant in AMO degradation. The preliminary chromatogram data display different products with varying pH reaction s, implying that AMO elimination using this 1 x 1 molecular sieve-structured MnO2 is by adsorption as well as oxidative degradation. A complementary experiment indicates that the amount of oxidatively degraded AMO increases substantially from 65.5% at 4 h to 95% at 48 h, whereas the AMO adsorbed onto MnO2 decreases slightly from 4.5% at4 h to 2.4% at 48 h. The oxidative degradation accounted for more AMO removal than adsorption over the whole reaction course, indicating that the oxidative reaction of AMO on MnO2 dominated the AMO removal.