THE ACTIVITY OF PROPHYLACTIC ANTIBIOTICS AGAINST BACTERIA COMMONLY ISOLATED FROM SPINAL SURGICAL WOUNDS.

Abstract

Recent work has demonstrated that intra-operative contamination of spinal surgical wounds is relatively common. The most frequently isolated wound contaminants are Propionibacterium spp. and coagulase negative Staphylococcus spp. The aim of this study is to examine the efficacy of prophylactic antibiotics used for spinal surgery against bacterial contaminants isolated from intra-operative samples retrieved during spinal surgical procedures.

Intra-operative wound samples were taken from 94 patients undergoing spinal surgery. Samples including skin, subcutaneous tissue and wound washings were processed, inoculated onto agar and incubated under both aerobic and anaerobic conditions for a period of 2 weeks. Bacterial growth was identified using commercially available biochemical test galleries. Thirty-six bacterial isolates were identified. The predominant bacteria isolated included Propionibacterium spp. (n=21) and coagulase negative Staphylococcus spp. (n=15). Each bacterial isolate was tested for its susceptibility to antibiotics used as antimicrobial prophylaxis during spinal surgery. Antibiotic sensitivities were determined in accordance with National Committee for Clinical Laboratory Standards (NCCLS) guidelines.

The antibiotic that performed best against Staphylococcus spp. isolated was ciprofloxacin with 93% of isolates being susceptible to this antibiotic. Cefamandole and cefuroxime also performed well against Staphylococcus spp. isolates.

The antibiotic that performed best against Propioni-bacterium spp. isolates was cefamandole with 100% of isolates being susceptible. Cefuroxime and ciprofloxacin also performed well. The antibiotic that performed least well against bacterial isolates was erythromycin with only 76% of Propionibacterium spp. and 47% of Staphylococcus spp. exhibiting susceptibility.

The results of this study demonstrate that ciprofloxacin, cefuroxime and cefamandole are effective against the majority of Propionibacterium spp. and Staphylococcus spp. isolated from within the spinal wound during surgery. The use of erythromycin in the penicillin allergic patient is questioned and ciprofloxacin proposed as a possible alternative.