Sato S, Sakuragi T, Dan K
Department of Anesthesiology, School of Medicine, Fukuoka University, Japan.
Anesthesiology. 1996 Dec;85(6):1276-82. doi: 10.1097/00000542-199612000-00008.
The mechanism of epidural infection associated with epidural block is not clearly understood. Resident organisms in skin specimens were studied after skin was prepared with disinfectants.
Sixty-nine paired skin specimens were excised at incisional sites after skin disinfection with 10% povidone-iodine (10% PVP-I) or 0.5% chlorhexidine in 80% ethanol (0.5% CHE) from 60 patients having back surgery. One of the specimen pairs was placed in 10 ml brain-heart infusion broth and incubated in air at 37 degrees C for 96 h. The other specimen was sectioned at 3 microns and prepared with Gram's stain for examination with the microscope.
Thirteen gram-positive staphylococcal species (Staphylococcus epidermidis, 69.2%; S. hyicus, 15.4%; and S. capitis, 15.4%) were isolated from cultures. The isolates were found in a significantly greater proportion of the skin specimens disinfected with 10% PVP-I than in those disinfected with 0.5% CHE (11 of 34 cultures [32.4%] vs. 2 of 35 cultures [5.7%]; P < 0.01). Many gram-positive cocci were observed with the microscope in 4 (11.8%) and 5 (14.3%) of 34 and 35 skin specimens disinfected with 10% PVP-I and 0.5% CHE, respectively. The cocci formed a dense colony in each follicle and in the stratum corneum. No organism was present in any of 17,584 sweat glands examined.
In a large proportion of patients, isolation of viable organisms from excised skin specimens after disinfection with 10% PVP-I suggests that contamination of the epidural space by the skin flora may be a potential mechanism of epidural infection associated with epidural block.
