Study of prophylactic antibiotics administration in cardiac operating room and during post operation ICU admission in Shahid Madani hospital (Tabriz)

Abstract

Surgical site infections are one of the most important post-surgery complications. Antimicrobial prophylaxis has been used routinely in cardiac surgeries to reduce the incidence of infection. However, inappropriate selection of the antimicrobial agents or dosing or excessive antibiotic usage can develop antimicrobial resistance or serious adverse reactions and prolong hospitalization. Aim of current study was to examine prophylactic antibiotic prescription in cardiac surgeries in Shahid Madani hospital, Tabriz and evaluate the level of adherence to the international guidelines.Patients and Methods 400 patients undergoing cardiac surgery between September 2010 and June 2011 in Shahid Madani hospital were enrolled in the study. The prophylactic antibiotics, dosage, timing of administration, post-operative antibiotics regimen (dose, dosing interval and duration) and indication to continuing or addition of therapeutic antibiotic because of infection signs and symptoms were collected by reviewing patients records and evaluated by comparing to the existing guidelines. Results Pre-operative prophylactic antibiotic was given to 99.5% of patients. Used antibiotics were cefazolin (98.25%; 1g), vancomycin (1.5%, 1g) and gentamycin with ampicillin (0.25%; 80mg and 2g, respectively). 77.75 % of patients received prophylactic antibiotic within 60 minutes of skin incision. Appropriate antibiotic dosage according to body weight was observed in 77.2%.Second antibiotic dose in off-pump surgeries (n=141) was indicated in 139 cases but administered in 97 patients and in one case with no indication, received a dose of antibiotic. The third dose was indicated in 10 cases but none received any antibiotics while one case received a third antibiotic dose without indication. In 64.75% of surgeries, cardiopulmonary bypass pump (CPB) was used. The second antibiotics after CPB initiation was cefazolin (n=151), vancomycin (n=99), cefazolin with vancomycin (n=2) and vancomycin with gentamycin (n=1). Starting of vancomycin infusion within 60 min of CPB initiation was observed in 7% of these patients while 65.75% received it at the same time of CBP initiation.All patients received post-operative prophylactic antibiotic. Main regimens were cefazolin (67.75%), vancomycin (15.5%), vancomycin plus amikacin (7.25%) and cefazolin plus vancomycin (3.25%). In 93.85% of CABG and OPCAB surgeries cefazolin and in 84.95% of valve replacement surgeries vancomycin was given. Only 12.25% of patients received an appropriate dosing interval of cefazolin (1g/8h). Only 3.5% of patients received antimicrobial prophylaxis for a total duration of 48 hours or less according to recommendations. Mean duration of antibiotic administration were 5.5 2.3 days for cefazolin and 7.24 6.3 days for vancomycin. Among those who received antibiotics longer than 48h post-surgery, infection signs and symptoms was seen only in 3.5%. In total7.5% of patients infection was developed, of which 38.5% was wound infection. One vancomycin-resistance Staphylococcus aureus was reported by disk diffusion method and one patient died because of mediastinitis. Discussion Antibiotic choice in 96.75% of patients was according to the guidelines but timing of antibiotic prophylactic was inappropriate in half of patients. In off-pump surgeries, was not given enough attention to the correct indication of repeating dosage and some patients received excess dose while some did not received enough antibiotic. Timing of antibiotics among CPB patients was incorrect in case of vancomycin infusion, which would result in insufficient level of vancomycin in blood or tissues at the necessary time which may increase risk of infection. Results of this study signified that adherence to existing guidelines was poor and the most common mistakes were changes in administrated antibiotics prior to, during and after surgery, over usage, inappropriate dosage and dosing interval of prophylactic antibiotics.