Comparison of Two Methods for Presurgical Disinfection of the Equine Hoof

OBJECTIVES: To determine for equine hooves the normal resident aerobic bacterial population and the efficacy of 2 methods of disinfection. Study Design-Measurement of total bacterial, gram-positive bacterial, and gram-negative bacterial surface populations from the frog, sole, and hoof wall after each step of 2 different preoperative surgical disinfection techniques. ANIMALS: Six adult horses. METHODS: Hoof wall, sole, and frog samples were collected for quantitative bacteriology before, during, and after 2 multistep antiseptic preparation techniques: Method A-6-minute scrub with povidone-iodine soap, followed by 24-hour submersion in povidone-iodine solution-soaked cotton; and Method B-initial removal of superficial layer of hoof capsule before completing Method A disinfection procedures. RESULTS: Removal of the superficial hoof layer, application of the povidone iodine scrub, and completion of the povidone-iodine soak all significantly (P < .0008) decreased total bacterial numbers. Method B had significantly lower bacterial counts than method A at each consecutive step. Final total bacterial counts remained greater than 10(5) bacteria per gram of tissue regardless of preparation method. CONCLUSIONS: The hoof surface hosts a broad spectrum of aerobic gram-positive and -negative bacteria, many of which are potential pathogens. Bacterial numbers can be significantly reduced by removal of the superficial hoof surface, by application of a povidone-iodine scrub, and by use of a 24-hour povidone-iodine soak. However, bacterial populations >10(5) g per tissue persist after these disinfection procedures. CLINICAL RELEVANCE: Regardless of the preparation methods used in this study, bacterial populations capable of inducing wound infection remain on the hoof capsule.     

Evaluation of Surgical Scrub Methods for Large Animal Surgeons

Objective— The objective of this study was to determine the effectiveness of a 5–minute surgical scrub using either a one-brush or a two-brush technique in clean and dirty surgical procedures, and to compare the efficacy of povidone iodine with chlorhexidine as surgical scrub solutions. Study Design— Prospective clinical trial. Methods— Nine veterinarians scrubbed their hands on eight separate occasions using either povidone iodine or chlorhexidine gluconate. A 5-minute scrub and either a one-brush or two-brush technique used in both clean and dirty operations were evaluated by taking glove juice samples before scrubbing, immediately after scrubbing, and 30, 60, 90, and 120 minutes after scrubbing. Glove juice samples were cultured and the colonies were counted. Percent reductions of bacterial forming units were calculated for all eight scrub procedures. Results— All scrub procedures provided an adequate percent reduction in colony forming units (CFU) during the 2–hour sampling period. The number of CFU immediately after scrubbing were significantly lower than prescrub. At 120 minutes, there were significantly fewer CFUs than presecrub, but there were more than immediately after scrubbing. No significant difference in reduction in CFUs were detected between one-brush and two-brush techniques. Both chlorhexidine and povidone iodine scrub solutions adequately reduced bacterial colony counts for 120 minutes after scrubbing regardless of the amount of contamination before skin preparation. Conclusions— Bacterial counts after a hand scrub procedure using a one-brush technique were not significantly different than after a procedure that used a two-brush technique. Povidone iodine and chlorhexidine are equally effectively in decreasing bacterial numbers on the skin, given a variety of contamination levels present before the scrub procedure. Clinical Relevance— Surgeons may use either chlorhexidine or povidone iodine for antiseptic preparation of their hands before surgery. A two-brush technique is not necessary.     

Comparison of three preoperative skin preparation techniques in ponies

The purpose of this study was to evaluate the efficacy of 3 preoperative skin preparations (povidone‐iodine [PI] removed with 70% isopropanol, and 4% chlorhexidine gluconate [CG] removed with either 70% isopropanol [CA] or sterile saline solution [CS]) in ponies. Eighteen ponies were randomly assigned to one of the 3 preoperative skin preparation groups. The skin of ponies was aseptically prepared with PI removed with alcohol, or 4% CG removed with either alcohol or sterile saline solution. The antimicrobial efficacy of each skin preparation technique was assessed quantitatively by culturing for surface bacteria with replicating organism detection and counting plates. The percentage of negative cultures, the percentage of cultures with >5 colony forming units (CFU) and the percentage bacterial reduction after the cleansing scrub, the sterile scrub, and the surgical procedures were compared. There was a significant difference between CG and PI in percentage bacterial reduction after the cleansing scrub, but no significant difference at any other time (sterile scrub, post operative skin sampling). In a comparison of the number of negative microbial cultures at each sampling point, there were no significant differences among the 3 skin preparation techniques. There were no significant differences among the treatment groups comparing the number of cultures with a high colony count (>5 CFU) after the cleansing scrub. Skin preparation with CS and PI resulted in significantly fewer cultures with >5 CFU after the sterile scrub than CA. Post operatively, CA had a higher number of samples with >5 CFU than CS and PI. PI removed with alcohol and 4% CS are equally effective in the reduction of skin bacteria after a sterile skin scrub in the operating room; however, CG was more effective in reducing bacterial numbers after the cleansing scrub. The number of cultures with high bacterial counts was greater post operatively, when alcohol was used as a rinse with chlorhexidine. In cases where a sterile scrub is not performed following a cleansing scrub, CG may be a better choice than PI. CA should not be used as a presurgical skin preparation method in ponies.     

Comparative Evaluation of Two Surgical Scrub Preparations in Cattle

One hundred seventeen cattle that had undergone surgery were assigned randomly to two preoperative skin preparation protocols. Group 1 (60 animals) skin preparation was with povidone-iodine soap and isopropyl alcohol, whereas group 2 (57 animals) had skin preparation with chlorhexidine gluconate and isopropyl alcohol. Quantitative microbial culture plates were used to estimate the number of colony forming units (CFUs) before skin preparation (prescrub), after skin preparation (postscrub), after surgery (postoperative), and in room air (environment). A significant decrease in CFU occurred postscrub for both skin preparations ( P <.05). Chlorhexidine and alcohol preparation resulted in significantly fewer CFUs (LSMean ± SE = 2.79 CFU ± 1.74) and a greater percentage reduction in CFUs (98.64%± 2.01) postscrub than povidone and alcohol (LSMean ± SE = 10.27 CFUs ± 1.51, 93.29%± 1.85); ( P <.005). Group 2 had a significantly higher frequency of negative cultures postscrub (49.1%) compared with group 1 (18.3%) ( P <.001). The number of postoperative CFUs were not significantly different between the two treatment groups. Wound infection frequency for clean surgical procedures was not significantly different between the two skin preparation protocols (group 1 = 9.8%, group 2 = 10.7%), however, infection frequency was significantly higher for surgical procedures with a ventral abdominal approach (5 of 14, 35.7%), compared with a flank approach (1 of 41, 2.4%) or other approaches (orthopedic procedures) (1 of 16, 6.3%) ( P <.05). Both skin preparation protocols were effective and safe in decreasing the skin microflora population of cattle before surgery and although preparation with chlorhexidine gluconate and alcohol resulted in less CFUs immediafly postscrub, the frequency of surgical wound infection was similar for both protocols.     

Comparison of Three Skin Preparation Techniques Part 2: Clinical Trial in 100 Dogs

The skin of 100 dogs undergoing clean or clean-contaminated surgical procedures was prepared with povidone-iodine (PI) or 4% chlorhexidine gluconate (CG) with saline or 70% isopropyl alcohol rinse. Skin bacteria at the incision site were quantified with Replication Organism Detection and Counting (RODAC) plates immediately before and after skin preparation in the preparation room, in the operating room, and postoperatively. The percentage of bacterial reduction, negative cultures, cultures with more than five colony-forming units, and skin reactions for each technique were calculated for each sample period and analyzed with the analysis of variance and Fischer tests. The percentage of bacterial reduction for all techniques was significant and comparable with results of a previous experimental study. There were no significant differences in percentages of bacterial reduction between PI and the CG techniques for surgical times up to 8 hours. There were fewer negative cultures and more cultures with high bacterial counts with PI than with CG and saline after the cleansing scrub. There were fewer negative cultures after surgery with CG and alcohol than with the other two techniques. Duration of the surgical procedure did not significantly affect the culture results. Significantly more skin reactions occurred with PI. The authors conclude that PI and 4% CG with a saline rinse are equally effective in antimicrobial efficacy under clinical conditions. However, 4% CG with a 70% isopropyl alcohol rinse may be inferior in residual antimicrobial activity.     

A prospective comparison between stabilized glutaraldehyde and chlorhexidine gluconate for preoperative skin antisepsis in dogs

OBJECTIVE: To compare the efficacy of 0.3% stabilized glutaraldehyde and alcohol (SG+A), 0.3% SG and water (SG+W), and 4% chlorhexidine gluconate tincture (CG+A), as skin disinfectants in dogs undergoing ovariohysterectomy. STUDY DESIGN: Prospective, blinded clinical study. ANIMALS: One hundred and twenty-one dogs. METHODS: Cutaneous bacterial colony forming units (CFU) from the perioperative site after skin preparation, after antisepsis, and after surgery (incisional and paramedian), were quantified. The influence of high initial bacterial counts (> or =150 CFU) and surgical time on antibacterial efficacy was examined and the proportion of dogs from which Staphylococcus intermedius was cultured, determined. Perioperative skin reactions and wound infections were documented. RESULTS: All 3 antiseptic solutions significantly and equally reduced CFU to all post-antisepsis sampling levels irrespective of surgical duration (mean surgical times 151.6, 136.2, and 149.6 minutes for CG+A, SG+A and SG+W, respectively). Median percentage reductions in CFU ranged between 99.3% and 100%. In dogs with initial high counts and disinfected with CG+A and SG+W, the incisional samples had significantly higher counts than the post-antisepsis samples. In the CG+A and SG+W groups, the proportion of post-surgery samples yielding S. intermedius was significantly higher at the incisional than the paramedian sites. Eight mild cutaneous reactions were recorded in equal proportions for the 3 solutions. There were no recorded infections. CONCLUSIONS: All 3 preparations had an equal ability to reduce and maintain low CFU counts, with minimal cutaneous reactions. CLINICAL RELEVANCE: SG solutions are safe and effective preoperative skin antiseptics for elective clean-contaminated surgical procedures.     

Presurgical hand antisepsis: concepts and current habits of veterinary surgeons

Objective: To assess current habits for surgical hand preparation among veterinary surgical specialists and to compare data with current guidelines for hand asepsis techniques. Study design: Survey of veterinary surgical specialists. Sample Population: Diplomates of the American (ACVS) and European Colleges of Veterinary Surgeons (ECVS). Methods: An internet‐based survey of hand preparation methods before surgical procedures was conducted of 1300 listed ACVS and ECVS Diplomates. Results: A 42.6% response rate was obtained. Approximately, 80% of respondents use disinfecting soaps as a primary method for hand antisepsis. Of those, 81% use chlorhexidine‐based scrubs and 7% use a neutral soap followed by a hydroalcoholic solution. Conclusions: Contrary to current recommendations of the World Health Organization and scientific evidence supporting use of hydro‐alcoholic rubs for presurgical hand preparation, veterinary surgical specialists still use surgical scrub solutions containing disinfecting soaps.     

Response of pony peritoneum to four peritoneal lavage solutions

Peritoneal lavage was performed on ponies to determine the effect on peritoneal surfaces. Lavage solution (20 L) was introduced into each pony's peritoneal cavity through catheters placed in the paralumbar fossa, and the solution was removed by drainage from the ventral portion of the abdomen. Six ponies each were lavaged with sterile saline (0.9% NaCl) solution, sterile saline solution containing 5 X 10(6) U of potassium penicillin and 3 g of neomycin or povidone-iodine diluted to 3% by volume with sterile saline solution, and 3 ponies were lavaged with povidone-iodine diluted to 10% with sterile saline solution. Peritoneal lavage catheters were inserted in 3 control ponies, but lavage fluids were not administered. Peritoneal fluid specimens were collected at 6, 24, 48, and 96 hours after lavage. Nucleated cell counts, RBC counts, total protein determinations, and cytologic analysis were performed. The ponies were euthanatized at 96 hours, and representative sections of the peritoneum were examined. Lavage with saline solution and saline solution with antibiotics induced a mild, transient inflammatory response in the peritoneal fluid, with minimal or no changes observed at necropsy. Solutions containing povidone-iodine induced chemical peritonitis, which was severe in ponies lavaged with 10% povidone-iodine solution. Peritoneal lavage with povidone-iodine solutions as dilute as 3% cannot be accomplished without causing inflammation of peritoneal surfaces.     

Effects of Chlorhexidine Diacetate and Povidone-lodine on Wound Healing in Dogs

To correlate the results of an in vitro study with clinical response, the effects of 0.005 and 0.05% chlorhexidine diacetate and 0.1 and 1.0% povidone-iodine concentrations on wound healing were evaluated in five beagle dogs. Full-thickness skin wounds (2 X 2 cm) were irrigated once daily for 14 days with the antiseptic solutions or physiologic-buffered saline. Chlorhexidine diacetate 0.05% had significantly more bactericidal activity than povidone-iodine and saline, and both chlorhexidine diacetate concentrations had residual effects 6 hours after irrigation. Neither povidone-iodine nor saline had significant bactericidal activity. The percentages of unhealed wound area and wound contraction were calculated 7, 14, and 21 days after wounding. Healed wound area and contraction were similar in wounds treated with chlorhexidine diacetate and povidone-iodine. However, wounds treated with chlorhexidine diacetate had more healed wound area on days 7 and 14 and more contraction on days 7, 14, and 21 than saline-treated wounds. At the concentrations tested, chlorhexidine diacetate irrigations provided bactericidal activity and were more beneficial to wound healing than irrigations with saline alone. These results suggest that concentrations of chlorhexidine diacetate which are cytotoxic to tissue culture fibroblasts in vitro do not interfere with wound healing in vivo.     

Evaluation of arthrocentesis site bacterial flora before and after 4 methods of preparation in horses with and without evidence of skin contamination

OBJECTIVE: To evaluate the effectiveness of four methods of povidone-iodine preparation on skin bacterial flora of arthrocentesis sites, in horses, with and without evidence of skin contamination. STUDY DESIGN: Prospective randomized study. ANIMALS: Twenty-four adult horses. METHODS: Horses were assigned to either the clean or contaminated group based on housing environment and visual evidence of contamination. Using a moist sterile swab, microbial culture samples were obtained from the skin over the distal interphalangeal joints immediately before and after preparation. Each site was aseptically prepared with 1 of 4 povidone-iodine techniques: 10-minutes scrub, 5-minutes scrub, three 30-second scrubs, or commercial one-step iodophor surgical solution. Colony forming units (CFUs) were determined for each sample, 24 hours after inoculation, on blood agar plates. RESULTS: Mean (+/-SD) pre-scrub CFUs/mL was significantly higher in the contaminated group (9588.33+/-1223.65) compared with the clean group (4489.00+/-3842.03) (P<.01). After preparation of the arthrocentesis sites, there were no significant differences in post-scrub CFUs/mL among the 10 minutes (mean clean, 46.00+/-64.36; mean contaminated, 28.67+/-18.04), 5 minutes (mean clean, 84.17+/-109.80; mean contaminated, 40.33+/-44.52), three 30 seconds povidone-iodine scrubs (mean clean, 95.50+/-172.29; mean contaminated, 46.67+/-56.94), or application of a commercial one-step iodophor surgical solution (mean clean, 102.17+/-161.78; mean contaminated 117.67+/-143.78); or between the clean (81.96+/-131.69) and contaminated groups (58.33+/-85.90) (P<.01). CONCLUSIONS: Preparation of the distal interphalangeal joint arthrocentesis site with each of these techniques significantly reduces the bacterial flora to a similar level for arthrocentesis in horses with and without evidence of skin contamination. Clinical Relevance- Aseptic preparation of the skin over the distal interphalangeal joint may be accomplished with any of these techniques.     

Comparison of an alcohol-based hand rub and water-based chlorhexidine gluconate scrub technique for hand antisepsis prior to elective surgery in horses

This prospective clinical study evaluates the effectiveness of an alcohol-based hand rub (Avagard™) for pre-surgical hand antisepsis in an equine hospital and compares it with traditional scrubbing technique using 4% chlorhexidine gluconate sponges and water. Prior to elective surgery, 3 board-certified surgeons were randomly assigned to hand antisepsis with either technique. Culture samples of each hand were taken at 4 times: before and after neutral soap hand wash, after scrub or rubbing technique, and after surgery. There was no significant difference in mean bacterial colony forming units between scrub and rub techniques over the 3 time periods (P = 0.6), controlling for initial counts. One horse from the scrub group had a skin incision infection following stifle arthroscopy; this was resolved with medical treatment. The alcohol-based hand rub is equivalent in efficacy for pre-surgical hand antisepsis to traditional water-based scrubs in an equine hospital setting.     

Antibacterial activity of dilute povidone-iodine solutions used for ocular surface disinfection in dogs

Bacterial cultures of specimens from healthy canine eyelids and ocular surfaces were found to demonstrate bacterial growth in 69.7% (53/76) of the eyes sampled. Organisms most commonly isolated included: Staphylococcus aureus, alpha-hemolytic Streptococcus sp, S epidermidis, and Escherichia coli. Evaluation of dilute povidone-iodine solutions for effectiveness as ocular surface disinfectants was conducted. Bacterial growth initially detected in 32 of 46 eyes was not detected after disinfection with a 2-minute scrub and 2-minute soaking procedure, using 1:2, 1:10, or 1:50 dilutions of a povidone-iodine solution that contained 1% available iodine. The eyelid and ocular surfaces of 16 eyes were disinfected with 1:100 povidone-iodine solution. Bacterial growth initially present in 10 of 16 eyes was present in 1 eye after disinfection and consisted of a single colony of E coli. After eyes were disinfected with 1:10, 1:50, or 1:100 povidone-iodine solutions, there was no evidence of corneal epithelial edema or sloughing. In 15 eyes subjected to disinfection with the 1:2 dilution, one instance of epithelial corneal edema was noticed. A 1:50 dilution of povidone-iodine is recommended as an ocular surface disinfectant for use in presurgical situations.     

Presurgical antiseptic efficacy of chlorhexidine diacetate and providone-iodine in the canine preputial cavity

Antiseptic flushing of the canine prepuce and its exclusion from the surgical field are recommended before abdominal surgery to reduce the risk of bacterial contamination. The authors cultured the preputial cavity of 60 dogs prior to and following flushing with 0.05% chlorhexidine diacetate, 1% povidone-iodine, or 0.9% saline control. Bacterial growth was evaluated using a semiquantitative method, and bacterial organisms were subsequently identified. There were no significant differences between povidone-iodine and the saline control in any of the variables assessed. Chlorhexidine resulted in a significant decrease in the proportion of positive postflush cultures compared with povidone-iodine. Although not significant, the difference in adverse reactions between povidone-iodine (25%) and chlorhexidine diacetate (5%) suggests clinical relevance. Based on the results of this study, a 2 min flush with 0.05% chlorhexidine diacetate is recommended for presurgical preparation of the preputial cavity.     

Chlorhexidine Gluconate Versus Chloroxylenol for Preoperative Skin Preparation in Dogs

The efficacy of 3% chloroxylenol (PCMX) or 4% chlorhexidine gluconate (CG) for preoperative skin preparation was assessed in 100 dogs undergoing clean or clean-contaminated surgical procedures. Replication Organism Detection and Counting (RODAC) plates were used to quantify skin bacteria colony forming units (CFU) at the operative site before and after skin preparation and immediately postoperatively. Reduction of CFU after skin preparation and immediately postoperatively was significant for each agent. However, CFU levels were significantly lower in the CG group than in the PCMX group after surgical preparation, regardless of initial CFU numbers. No significant difference in CFU counts was observed between antiseptic groups postoperatively. Within-group comparisons showed PCMX to be significantly less efficacious when the prescrub CFU number was greater than 1,000. Bacterial reduction was similar in the CG group regardless of prescrub CFU levels. The number of negative cultures after skin preparation was significantly greater with CG than with PCMX. Chlorhexidine gluconate also had fewer cultures with heavy bacterial growth (>5 CFUs) after surgical preparation. There was no significant difference between antiseptics in the number of negative cultures or cultures with more than 5 CFUs immediately after surgery. The number of skin reactions and postoperative wound infections that occurred with each technique were similar. Three percent PCMX, as used in this study, was less effective than 4% CG in its immediate antimicrobial activity, however, this difference was not associated with an increased wound infection rate.     

“可得福”聚维酮碘与碘酊对犬腹部手术伤口的消毒效果比较

为了观察聚维酮碘消毒剂"可得福"对犬手术伤口的消毒效果,选用2～3月龄、3～5 kg的本地杂交犬10只,随机分为试验组和对照组,试验组选用1.0%～0.5%"可得福",对照组选用2%碘酊和0.1%苯扎溴铵,在相同的手术条件与伤口情形下,对比两组犬分别使用上述药液涂擦或清洗对手术伤口的影响。结果显示,使用"可得福"消毒的有效性和安全性优于2%碘酊和0.1%苯扎溴铵。     

Microbiologic evaluation of canine urine: direct microscopic examination and preservation of specimen quality for culture

Urine specimens were obtained from 115 dogs. Each specimen was divided into 2 aliquots; one aliquot was placed into a sterile container (non-preserved), and the other was preserved in a boric acid-glycerol-sodium formate at 4 C. Both aliquots were then transported to a laboratory, and specimens of each aliquot were bacteriologically cultured immediately upon arrival at the laboratory. Specimens of the preserved aliquot also were cultured after 24, 48, and 72 hours of preservation. In 47 specimens containing greater than or equal to 1 X 10(4) colony-forming units (CFU)/ml, the results of quantitative bacteriologic culturing of preserved urine at 0, 24, 48, and 72 hours were the same as the result of the immediate quantitative bacteriologic culture of non-preserved urine. In 2 of 5 specimens containing greater than or equal to 1 X 10(3) CFU/ml but less than 1 X 10(4) CFU/ml, the results of quantitative bacteriologic culture of preserved urine differed from the corresponding immediate culture of nonpreserved urine. Bacteria were not isolated from 63 specimens (less than 1 X 10(3) CFU/ml). Bacteriologic cultures of preserved urine were also negative for bacterial growth at 0, 24, 48, and 72 hours. Bacteriuria was detected by direct microscopic examination of gram-stained smears of uncentrifuged urine in 50 of 52 urine specimens from dogs with urinary tract infection. Bacteria were observed in 1 of 63 specimens that did not have bacterial growth when cultured.     

Comparison of Three Skin Preparation Techniques in the Dog Part 1: Experimental Trial

Premeasured, clipped areas of skin on both sides of 30 adult dogs were prepared with povidone-iodine (PI), chlorhexidine gluconate (CG) with a saline rinse, or 4% CG with a 70% isopropyl alcohol rinse. Skin bacteria were quantified with Replicating Organism Detection and Counting (RODAC) plates and cultured for identification before, immediately after, and 1 hour after skin preparation. The percentages of bacterial reduction immediately and at hour 1 and the percentages of negative cultures, cultures with more than five colony-forming units (CFUs), and skin reactions were analyzed by analysis of variance and chi-square. The percentage of reduction in skin bacteria for all techniques was significant and comparable with that reported in humans. There were no significant differences between PI and CG results except that acute contact dermatitis was observed more frequently after skin preparation with PI. The authors conclude that for similar application times, PI and 4% CG rinsed with saline or 70% isopropyl alcohol are equally effective for up to 1 hour in the preoperative skin preparation of dogs.     

Abstract of Current Literature

Summary: Orthopaedic surgeons in many major arthroplasty centres advocate the use of a prolonged surgical hand-scrub prior to total joint replacement. In this study we evaluated the antimicrobial efficacy of a 5 compared with a 10 min scrub before both long (>90 min) and short (<90 min) operations for total hip arthroplasty. Surgical hand disinfection was performed on one occasion for 5 min and on a second for 10 min by 41 surgeons and theatre nurses using 4% chlorhexidine gluconate as a detergent formulation ('Hibiscrub', ICI Pharmaceuticals). None of the subjects had previously scrubbed on the day of each test. Bacterial colony counts on the fingers were measured using the method described by Rotter (vide infra) before scrubbing, immediately after scrubbing, and at the end of each operation. Our results showed that for arthroplasty procedures lasting less than 90 min (35 operations) a 5 min hand-scrub was equally as effective as one of 10 min. However, following longer procedures (36 operations) colony counts were significantly higher on subjects who had scrubbed for 10 min than on those who only scrubbed for 5 ( P < 0.05, Mann-Whitney U -Test). This study suggests that the practice of a prolonged scrub before total joint replacement does not have a scientific basis and that such a policy should be discontinued where it is still practised. © 1994 The Hospital Infection Society     

Evaluation of otoscope cone cleaning and disinfection procedures commonly used in veterinary medical practices: a pilot study

The objective of this study was to evaluate the relative efficacy of otoscope cone cleaning and disinfection methods commonly used in veterinary practices. Using sterile technique, 60 new gas-sterilized 4-mm otoscope cones were inoculated with a broth culture of 1.5 billion Pseudomonas aeruginosa bacteria per mL then allowed to dry for 10 min. Six study groups of 10 cones each were created. Group 1 served as positive control and received no cleaning or disinfection. Group 2 cones were wiped with sterile cotton-tipped applicators and gauze then rinsed with water. Group 3 cones were wiped with 70% isopropyl alcohol. Group 4 cones were scrubbed in a speculum cleaner with Cetylcide II solution (Cetylite Industries, Inc., Pennsauken, NJ). Groups 5 and 6 cones were soaked for 20 min in Cetylcide II and chlorhexidine gluconate 2% solutions, respectively. Using sterile technique and after 10-15 min drying time, the cones were swabbed in a consistent pattern, and samples were submitted for quantitative culture. Culture results showed no growth from cones soaked in Cetylcide II or chlorhexidine solutions. Two of the 10 cones wiped with alcohol, 3/10 cones wiped then rinsed with water, and 3/10 cones scrubbed with the speculum cleaner showed growth of P. aeruginosa. All (10/10) cones in the control group showed heavy growth of P. aeruginosa. These results show that P. aeruginosa can survive on otoscope cones cleaned and disinfected by several commonly used methods. Further study is needed to determine practical and optimal cleaning and disinfection methods for otoscope cones.