• View in gallery

    Photograph to illustrate skin site preparation on the ventral aspect of the abdomen of a dog (head is to the right of the image) in a study to compare the efficacy of application of an ABAHR with that of a CGS2 for immediate reduction of the bacterial population on the skin of dogs. Two sections (each 12 × 12 cm) of hair were clipped with a sterile No. 40 clipper blade. Each clipped section was designated for application of either the ABAHR or the CGS2.

  • View in gallery

    Photograph to illustrate the application of a direct contact plate to 1 of the 2 clipped skin sites on the ventral aspect of the abdomen of the dog in Figure 1 (head is to the right of the image). Before and after application of the ABAHR or CGS2 at each skin site, a direct contact plate was applied with gentle pressure to the skin surface by a person wearing sterile gloves to obtain a sample for bacterial culture and quantification of bacterial load. For all sample collections, the duration of contact between the plate and the skin site was 2 seconds. Contact plates contained tryptic soy agar with lecithin and polysorbate 80 to inactivate both chlorhexidine gluconate and alcohol.

  • View in gallery

    Distribution of the percentage bacterial load reduction on ventral abdomen skin sites of 50 dogs (2 sites/dog) resulting from the application of an ABAHR (orange bars) or CGS2 (blue bars). Samples were collected by use of direct contact plates from each skin site before and after application of the ABAHR or CGS2. The postapplication percentage bacterial load reduction was calculated for each preparation as follows: ([number of CFUs in preapplication sample minus the number of CFUs in the postapplication sample] divided by the number of CFUs in preapplication sample) multiplied by 100. There was no significant difference in the percentage bacterial load reduction achieved by application of the ABAHR or CGS2. One bacterial culture from the ABAHR and the CGS2 treatment groups was removed from the analysis because each sample had colonies that were too numerous to count and could not be analyzed.

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  • 16. Paulson DS. Comparative evaluation of five surgical hand scrub preparations. AORN J 1994;60:246256.

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  • 18. Sanchez IR, Swaim SF, Nusbaum KE, et al. Effects of chlorhexidine diacetate and povidone-iodine on wound healing in dogs. Vet Surg 1988;17:291295.

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  • 19. Leschke M. Ethylhexylglycerin for improved skin feel. Int J Appl Sci 2010;138:1014.

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  • 21. Kampf G, Ostermeyer C, Heeg P, et al. Evaluation of two methods of determining the efficacies of two alcohol-based hand rubs for surgical hand antisepsis. Appl Environ Microbiol 2006;72:38563861.

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  • 22. Bajaj TI, Loh C, Borgstrom D. Diluting chlorhexidine gluconate: one scrub or two? Surg Infect (Larchmt) 2014;15:544547.

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  • 25. Chae SB, Kim WK, Yoo CJ, et al. Fires and burns occurring in an electrocautery after skin preparation with alcohol during a neurosurgery. J Korean Neurosurg Soc 2014;55:230233.

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  • 26. Tooher R, Maddern GJ, Simpson J. Surgical fires and alcohol-based skin preparations. ANZ J Surg 2004;74:382385.

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  • 28. US FDA. Preventing surgical fires: FDA safety communication. Date issued: Oct. 13, 2011. Available at: www.fda.gov/Drugs/DrugSafety/SafeUseInitiative/PreventingSurgicalFires/default.htm. Accessed Aug 8, 2017.

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  • 29. Eugster S, Schawalder P, Gaschen F, et al. A prospective study of postoperative surgical site infections in dogs and cats. Vet Surg 2004;33:542550.

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  • 33. Ritter MA, French ML, Eitzen HE, et al. The antimicrobial effectiveness of operative-site preoperative agents. J Bone Joint Surg Am 1980;62:826828.

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  • 36. Directorate for the Quality of Medicines of the Council of Europe (EDQM). Amended chapters 2.6.12, 2.6.13, 5.1.4. In: European pharmacopoeia. Strasbourg, France: Council of Europe, 2007.

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Efficacy of application of an alcohol-based antiseptic hand rub or a 2% chlorhexidine gluconate scrub for immediate reduction of the bacterial population on the skin of dogs

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  • 1 Lauderdale Veterinary Specialists, 3217 NW 10th Terr, Stes 302–306, Fort Lauderdale, FL 33309.
  • | 2 Lauderdale Veterinary Specialists, 3217 NW 10th Terr, Stes 302–306, Fort Lauderdale, FL 33309.
  • | 3 Department of Veterinary Clinical Medicine, College of Veterinary Medicine, University of Illinois, Urbana, IL 61802.

Abstract

OBJECTIVE To compare the efficacy of application of an alcohol-based antiseptic (80% ethyl alcohol) hand rub (ABAHR) with that of a 2% chlorhexidine gluconate scrub (CGS2) for immediate reduction of the bacterial population on the skin of dogs.

ANIMALS 50 client-owned dogs with no evidence of skin disease.

PROCEDURES On each dog, 2 areas of hair on the ventral aspect of the abdomen were clipped with a No. 40 blade and cleared of debris. A direct contact plate holding tryptic soy agar with polysorbate 80 and lecithin was gently pressed (for 2 seconds) on each skin site (preapplication sample). The CGS2 and ABAHR were each aseptically applied to 1 skin site on each dog. A direct contact plate was subsequently applied to each site in a similar manner (postapplication sample). All plates were cultured, and bacterial isolates were identified and quantified by the number of CFUs per plate.

RESULTS Application of the CGS2 and ABAHR significantly decreased skin bacterial colony counts, compared with findings for preapplication samples. The number of CFUs per plate or postapplication percentage reduction in CFUs per plate did not differ between treatments. There were no adverse skin reactions associated with either application.

CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that applications of ABAHR and CGS2 were equally effective at immediately reducing the bacterial population on the skin of dogs, and there was no significant difference in percentage reduction in colony counts between the 2 applications.

Abstract

OBJECTIVE To compare the efficacy of application of an alcohol-based antiseptic (80% ethyl alcohol) hand rub (ABAHR) with that of a 2% chlorhexidine gluconate scrub (CGS2) for immediate reduction of the bacterial population on the skin of dogs.

ANIMALS 50 client-owned dogs with no evidence of skin disease.

PROCEDURES On each dog, 2 areas of hair on the ventral aspect of the abdomen were clipped with a No. 40 blade and cleared of debris. A direct contact plate holding tryptic soy agar with polysorbate 80 and lecithin was gently pressed (for 2 seconds) on each skin site (preapplication sample). The CGS2 and ABAHR were each aseptically applied to 1 skin site on each dog. A direct contact plate was subsequently applied to each site in a similar manner (postapplication sample). All plates were cultured, and bacterial isolates were identified and quantified by the number of CFUs per plate.

RESULTS Application of the CGS2 and ABAHR significantly decreased skin bacterial colony counts, compared with findings for preapplication samples. The number of CFUs per plate or postapplication percentage reduction in CFUs per plate did not differ between treatments. There were no adverse skin reactions associated with either application.

CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that applications of ABAHR and CGS2 were equally effective at immediately reducing the bacterial population on the skin of dogs, and there was no significant difference in percentage reduction in colony counts between the 2 applications.

Preoperative skin preparation in patients undergoing surgery is essential for minimizing the risk of SSIs.1 The ideal antiseptic used for preoperative skin preparation should rapidly decrease the number of microorganisms, maintain this low number, be safe to use on the skin, and be amenable to application in a timely manner.1 The FDA has proposed criteria for patient-use preoperative skin preparations, namely a 2-log postapplication reduction in the microbial fora of an abdominal skin test site per square centimeters and the suppression of bacterial growth (ie, to a level less than that determined before application) for 6 hours.2 Currently, the most common skin preparations used in human and veterinary medicine are povidone-iodine solution, chlorhexidine gluconate scrub, and isopropyl alcohol.3 In a systematic review and meta-analysis4 of the efficacy of chlorhexidine gluconate preparations, many articles attributed study outcomes solely to the chlorhexidine gluconate component, despite the fact that chlorhexidine gluconate–alcohol combinations were used in those studies and would have likely affected the outcomes. The role of alcohol is frequently overlooked in these assessments.

The antimicrobial activity of alcohols results from their ability to denature proteins.5 Alcohols have excellent in vitro germicidal activity against gram-positive and gram-negative bacteria.5,6 Alcohols have no appreciable residual activity; however, regrowth of bacteria on skin occurs slowly, presumably because of the sublethal effect alcohols have on some bacteria.6,7 The addition of an emollient and preservatives in alcohol-based antiseptics has been shown to result in prolonged activity against transient bacteria.8

In a study9 comparing hand rubbing with an alcohol-based solution and traditional hand scrubbing with 4% chlorhexidine solution, it was shown that hand rubbing was equivalent to the traditional hand-scrubbing techniques for prevention of SSIs. The World Health Organization guidelines recommend alcohol-based hand rubs for surgical hand antisepsis because such rubs are fast acting, have broad-spectrum antimicrobial activity, are suitable for use in resource-limited areas, promote improved compliance with hand hygiene, have economic benefit, and result in minimal adverse effects.10

The purpose of the study reported here was to compare the efficacy of application of an ABAHR (80% ethyl alcohol) with that of a CGS2 for immediate reduction of the bacterial population on the skin of dogs. The intent was to assess efficacy by quantitative and qualitative evaluation of bacterial load on the skin of dogs before and after application of the ABAHR or CGS2. The hypotheses tested were that both antiseptics would significantly reduce bacterial load, compared with preapplication findings, and there would be no difference in the bacterial load reduction between the 2 preparations.

Materials and Methods

An experimental trial involving 50 client-owned dogs was performed. Dogs were included in the study if they were voluntarily enrolled by their owners or were scheduled for either a surgical procedure or an ultrasonographic examination. Owner consent for participation of each dog was obtained. Dogs were excluded from the study if immune function was considered to be weakened as a result of acquired immune deficiency, such as that associated with neoplastic disease, immunemediated disease, endocrine disease, or drug treatment (ie, administration of steroids, chemotherapy, or immunosuppressants). Dogs were also excluded if they had a previously known skin allergy, evidence of a superficial pyoderma, or weighed < 20 kg. Dogs scheduled for surgery or ultrasonography were either sedated or anesthetized during the study testing. Unsedated dogs that did not tolerate lying in a trough were excluded from the study. The study protocol was performed in compliance with institutional guidelines for research on animals.

Skin site preparation

Skin preparation of all dogs was performed by the same veterinarian (EAM). On the ventral aspect of the abdomen of each dog, 2 sections (a cranial and a caudal site; each 12 × 12 cm) of hair were clipped with a sterile No. 40 clipper blade, and all hair and debris were removed with a vacuum and dry sterile 4 × 4-inch gauze sponges (Figure 1). Each clipped skin site was designated for either CGS2a or ABAHRb application. The first dog had the cranial and caudal site treatment designated by use of a coin toss; with each dog subsequently included in the study, designated treatments of sites were alternated. A direct contact plate was pressed onto each skin site of each dog before (preapplication sample) and after ABAHR or CGS application (postapplication sample) for bacterial culture and subsequent quantitative assessment of bacterial load. To collect each culture sample, sterile gloves were donned by the investigator and a direct contact plate holding tryptic soy agar with polysorbate 80 and lecithinc (to inactivate both chlorhexidine gluconate and alcohol) was applied with gentle pressure to the skin surface (Figure 2). The duration of contact between the plate and the skin site was 2 seconds.

Figure 1—
Figure 1—

Photograph to illustrate skin site preparation on the ventral aspect of the abdomen of a dog (head is to the right of the image) in a study to compare the efficacy of application of an ABAHR with that of a CGS2 for immediate reduction of the bacterial population on the skin of dogs. Two sections (each 12 × 12 cm) of hair were clipped with a sterile No. 40 clipper blade. Each clipped section was designated for application of either the ABAHR or the CGS2.

Citation: American Journal of Veterinary Research 79, 9; 10.2460/ajvr.79.9.1001

Figure 2—
Figure 2—

Photograph to illustrate the application of a direct contact plate to 1 of the 2 clipped skin sites on the ventral aspect of the abdomen of the dog in Figure 1 (head is to the right of the image). Before and after application of the ABAHR or CGS2 at each skin site, a direct contact plate was applied with gentle pressure to the skin surface by a person wearing sterile gloves to obtain a sample for bacterial culture and quantification of bacterial load. For all sample collections, the duration of contact between the plate and the skin site was 2 seconds. Contact plates contained tryptic soy agar with lecithin and polysorbate 80 to inactivate both chlorhexidine gluconate and alcohol.

Citation: American Journal of Veterinary Research 79, 9; 10.2460/ajvr.79.9.1001

Following collection of the preapplication samples, the investigator donned another pair of sterile gloves and applied CGS2 to a sterile 3 × 3-cm gauze square. The soaked gauze was touched onto the center of the designated skin site; while maintaining skin contact, the gauze was moved outward incrementally in concentric circles, extending to the periphery of the skin site. The CGS2 was allowed to remain on the dog's skin for 2 minutes (according to the manufacturer's instructions11) and was then wiped off with dry sterile gauze in the same concentric motion. The CGS2 application was performed first in all cases. The ABAHR was sprayed onto the second site until the surface was saturated and then allowed to evaporate for at least 2 minutes. A direct contact plate handled with sterile gloves was applied to each site in the manner described previously. For dogs that were subsequently undergoing a surgical procedure, final skin preparation with CGS2 was performed to ensure that all surgical patients received adequate skin antisepsis prior to surgery.

Bacterial culture

All direct contact plates were incubated at 36°C in an atmosphere containing 5% CO2. After 48 hours, CFUs were counted with a binocular stereoscope by the same person who was unaware of the antiseptic technique used. Samples of all colony morphologies were picked for isolation and streaked onto tryptic soy agar with 5% sheep blood, MacConkey agar, Hektoen enteric agar, and Sabouraud-dextrose agar with chloramphenicol. Resultant colonies were stained with Gram stain. Gram-positive cocci were tested for catalase, β-hemolysis, and motility. Colonies that had a negative catalase test result underwent a bile esculin test, sodium hippurate hydrolysis test, and differential tests on an “A” (bacitracin susceptibility) disk and a vancomycin susceptibility disk. Gram-negative rods were tested for oxidase reaction. If the result for a colony was positive, a glucose nonfermenter strip was inoculated; if the result for a colony was negative (indicative of a glucose fermenter), a biochemical panel for identification and differentiation of members of the family Enterobacteriaceae was used.

The efficacy of the skin preparation protocols with the ABAHR or CGS2 was expressed as a percentage reduction in CFUs, compared with findings for the preapplication samples. The postapplication percentage bacterial load reduction was calculated for each preparation. For each preparation, the postapplication percentage bacterial load reduction was calculated as the number of CFUs in the preapplication sample minus the number of CFUs in the postapplication sample, divided by the number of CFUs in the preapplication sample, and multiplied by 100.

Adverse effect monitoring

Dogs were examined for local adverse reactions to the skin preparations during the immediate postapplication period (approx 10 minutes). The skin sites were graded on the basis of a scoring system in which 0 = no visible skin reaction, 1 = minimal erythema, 2 = well-defined erythema, 3 = erythema and edema, and 4 = erythema, edema, and urticaria. Owners were telephoned 5 days after the testing period and questioned regarding any local adverse reactions that their dog had developed.

Data and statistical analyses

The sample size used for the study was determined on the basis of a priori information as follows: α, 0.05; power, 0.9; and expected reduction in bacterial load between pre- and postapplication samples, ≥ 50%. The sample size determination suggested a sample size of 48 dogs; however, we recruited 50 dogs in case of loss to follow-up.

For purposes of analysis, data from all preapplication samples were combined, as were data from ABAHR-treated sites or the CGS2-treated sites. The distribution of the data was evaluated with a Shapiro-Wilk test, skewness, kurtosis, and q-q plots. Because the data were not normally distributed, they are reported as the median, interquartile range (ie, 25th to 75th percentile), and minimum and maximum values. In addition, the data were logarithmically transformed for parametric analysis. One bacterial culture from the ABAHR and the CGS2 treatment groups was removed from the analysis because each sample had colonies that were too numerous to count and could not be analyzed. A mixed linear model was used to determine whether there was a significant difference in number of CFUs per plate between the preapplication (baseline) samples and the ABAHR or CGS2 postapplication samples. Dog was included in the model as a random variable, and sample number and treatment were included in the model as fixed variables. A related-samples Wilcoxon signed rank test was used to determine whether there was a significant difference between the ABAHR and CGS2 postapplication percentage bacterial load reductions. Computer softwared was used to analyze the data. A value of P < 0.05 was used to determine significance. A cost comparison between use of the ABAHR and the CGS2 was also performed.

Results

The total bacterial colony counts (ie, number of CFUs per plate) for the preapplication (baseline) samples for all skin sites (whether they were assigned to receive the CGS2 or ABAHR) were determined (Table 1). There was a significant difference in the median number of CFUs per plate among the 3 groups (P < 0.001). The preapplication bacterial colony counts were significantly higher than either the CGS2 (P < 0.001) or ABAHR (P < 0.001) postapplication CFU counts. There was no difference (P = 0.704; power = 0.130) between the numbers of CFUs per plate for the postapplication CGS2 and ABHR samples. The postapplication percentage bacterial load reduction achieved following application of either the CGS2 or ABAHR did not differ (P = 0.179; power = 0.152). Distribution of the percentage bacterial load reduction on the skin sites resulting from application of the ABAHR or CGS2 was assessed (Figure 3). One of the CGS2 treatments (% change [colony counts: control, CGS2]:–150% [6, 15]) and 2 of the ABAHR treatments (% change [colony counts: control, ABAHR]:–150% [2, 5] and −8% [124, 134]) had more bacterial colonies after treatment than before treatment (preapplication).

Figure 3—
Figure 3—

Distribution of the percentage bacterial load reduction on ventral abdomen skin sites of 50 dogs (2 sites/dog) resulting from the application of an ABAHR (orange bars) or CGS2 (blue bars). Samples were collected by use of direct contact plates from each skin site before and after application of the ABAHR or CGS2. The postapplication percentage bacterial load reduction was calculated for each preparation as follows: ([number of CFUs in preapplication sample minus the number of CFUs in the postapplication sample] divided by the number of CFUs in preapplication sample) multiplied by 100. There was no significant difference in the percentage bacterial load reduction achieved by application of the ABAHR or CGS2. One bacterial culture from the ABAHR and the CGS2 treatment groups was removed from the analysis because each sample had colonies that were too numerous to count and could not be analyzed.

Citation: American Journal of Veterinary Research 79, 9; 10.2460/ajvr.79.9.1001

Table 1—

Bacterial loads in samples obtained from ventral abdomen skin sites on 50 dogs (2 sites/dog) before and after ABAHR or CGS2 application and postapplication percentage bacterial load reduction, compared with preapplication findings.

VariableMedianInterquartile range*Minimum to maximum value
Preapplication samples (No. of CFUs/plate [n = 98])2710.0 to 50.70 to 217
Postapplication samples (No. of CFUs/plate [n = 48])   
 CGS231.0 to 14.00 to 50
 ABAHR41.0 to 15.50 to 134
Postapplication reduction in bacterial load (% [n = 48])   
 CGS29271.2 to 98.0–150 to100
 ABAHR8357.0 to 97.7–150 to 100

On each dog, 2 areas of hair on the ventral aspect of the abdomen were clipped with a No. 40 blade and cleared of debris. A direct contact plate holding tryptic soy agar with polysorbate 80 and lecithin was gently pressed (for 2 seconds) onto each skin site (preapplication sample). The CGS2 and ABAHR were each aseptically applied to 1 skin site on each dog. A direct contact plate was subsequently applied to each site in a similar manner (postapplication sample). All plates were cultured, and bacterial isolates were identified and quantified by the number of CFUs per plate. The postapplication percentage bacterial load reduction was calculated for each preparation as follows: (number of CFUs in preapplication sample minus the number of CFUs in the postapplication sample divided by the number of CFUs in preapplication sample) multiplied by 100. One bacterial culture from the ABAHR and the CGS2 treatment groups was removed from the analysis because each sample had colonies that were too numerous to count and could not be analyzed.

Interquartile range = 25th to 75th percentile.

Value for postapplication samples differs significantly (P < 0.001) from the value for the preapplication samples.

None of the dogs developed any local adverse reactions at any time during the study (immediately after ABAHR or CGS2 application or during the 5-day follow-up period after testing), and all were assigned a score of 0 based on the described scoring system. A few dogs that were not anesthetized or sedated at the time of ABAHR application appeared subjectively to become less compliant with restraint, but this was not quantified. To compare costs between treatment protocols, the volume of CGS2 and ABAHR used on the 50 skin sites was calculated; 1,800 mL of CGS2 and 123 mL of ABAHR were each used to prepare 50 sites, at a cost of $10.90 and $9.60, respectively.

Bacillus sp and Staphylococcus pseudintermedius were the 2 most common microorganisms grown from direct contact plate samples obtained before and after skin preparation. Bacillus sp was cultured from all positive pre- and postapplication samples. Staphylococcus pseudintermedius was cultured from 36% (18/50) of preapplication samples, 2% (1/50) of CGS2 postapplication samples, and 4% (2/50) of ABAHR postapplication samples.

Discussion

With regard to an immediate reduction in the bacterial population of the skin in dogs, results of the present study indicated that the ABAHR was as effective as the CGS2 when used in accordance with the manufacturer's recommendations. There was no significant difference in postapplication percentage bacterial load reduction achieved by use of the 2 preparation protocols.

The ABAHR used in the present study was a presurgical hand antiseptic containing 80% ethyl alcohol with emollients.12 Unlike the CGS2, which has been investigated for use both as a hand antiseptic and as a preoperative patient skin preparation, ABAHRs are not currently marketed for use as a patient skin preparation. As a result, information regarding the efficacy of such rubs is limited to their use as hand antiseptics.13–15 Various ABAHRs have been shown to be as effective at reducing bacterial counts on hands prior to surgery as chlorhexidine gluconate and povidone iodine.9 The ABAHR used in the present study has proven to have favorable dermal tolerance with emollient effects superior to that of 6 other alcohol-based hand rubs.15 In the present study, no dogs developed any local skin reactions or dermal irritation after application of the ABAHR or the CGS2. A few dogs that were not anesthetized or sedated were noted to become less compliant with restraint (slight movement) for a few seconds after application of the ABAHR, but this effect was not quantified. None of the dogs moved during application of the direct contact plates. It was difficult to determine whether the dogs were reacting to the sound of the ABAHR spray, evaporative cooling, or a transient stinging sensation often associated with alcohols on skin that is irritated following hair clipping. Although no dog in the study had any obvious signs of clipper-induced irritation, it cannot be ruled out as a source of discomfort. Nevertheless, the reaction to the ABAHR was of short duration, and it should be remembered that this type of skin preparation is most often performed on anesthetized animals.

In a study16 that compared 5 surgical hand preparations, chlorhexidine gluconate 2% and chlorhexidine gluconate 4% both achieved a 2-log reduction in microorganism load, compared with the preapplication baseline counts. Those researchers concluded that both chlorhexidine concentrations were equivalent in antimicrobial effectiveness, with the CGS2 having comparatively less irritation potential to hands.16 In another study,17 there was no significant difference in the efficacy of chlorhexidine gluconate solutions of differing concentrations (1% to 4%) as a patient skin preparation. On the basis of these results, the CGS2 was chosen for assessment in the present study. One advantage of chlorhexidine gluconate is its residual antimicrobial effect that can last for as long as 6 hours.16–18 Although alcohols have no appreciable residual activity alone, the addition of an emollient (ethylhexylglycerin) to an alcohol-based formulation provides a vehicle for persistent activity.8 Because of its surfactant-like structure, ethylhexylglycerin affects the interfacial tension at the cell membrane of microorganisms, thereby allowing active ingredients, such as antimicrobials, to penetrate more effectively.19 A similar emollient (ethylhexyl ethylhexanoate) was present in the ABAHR used in the present study.

A 2-minute application of an ethanol-based hand rub has been shown to reduce the mean preapplication baseline skin bacterial count (a 2.99-log10 change) immediately after application; 6 hours after treatment, the bacterial count remained at least 1.54 log10 less than baseline.16 Thus, alcohol-based products with emollients are suitable for use as preoperative skin preparations because they adhere to criteria set forth by the FDA for preoperative patient skin preparations.2

In the present study, we found a 1-log10 reduction in bacterial counts after application of either the ABAHR or CGS2. Although the FDA approves products for preoperative patient skin preparation on the basis of a microbiological end point of log reductions in bacterial counts, there is no evidence to suggest that specific reductions in counts of microorganisms on the skin achieved by use of common preoperative skin preparation products are associated with reductions in the incidence of SSIs.20,21 Further studies are warranted to establish a CFU threshold for relevant skin pathogens below which SSIs are unlikely to develop.

The manufacturer's guidelines for CGS2 recommend application of the product to the surgical site for at least 2 minutes followed by drying of the site with a sterile towel and then repetition of the process.11 In clinical practice, the surgical site is often prepared by application of a chlorhexidine gluconate scrub to the surgical site and scrubbing until the swabs appear clean; understandably, the concentrations of the preparations and the time taken to perform the scrub are variable.17 In a human study22 in which the effectiveness of 1 scrubbing was compared with the effectiveness of 2 scrubbings (applied per the manufacturer's guidelines), most of the subjects had no bacteria growth after 1 scrubbing. For the study reported here, we chose a scrub time of 2 minutes because it has been shown that this scrub time was effective in reducing the natural bacterial flora of the hands and maintaining those reductions for 6 hours.23 The CDC's guidelines for prevention of surgical wound infections recommend a patient's skin be prepared by applying an antiseptic in concentric circles beginning in the area of the proposed skin incision and progressing to the periphery of the surgical site.24 On the basis of these recommendations, skin preparation for the dogs in the present study was performed in this manner; however, this technique has not been proven to be superior to any other application technique.

There have been several reports25,26 of operating room fires that have occurred secondary to in-room use of an alcohol-based skin preparation. Although infrequent, it is recommended that any alcohol-based skin preparation used on a surgical patient be allowed to dry completely prior to draping.26,27 The FDA guidelines for health-care professionals on preventing surgical fires include avoidance of pooling of alcohol-based antiseptics on skin during preparation, provision of adequate drying time, and assurance that the skin is dry before draping and beginning surgery.28 To the authors’ knowledge, operating room fires secondary to use of an alcohol-based skin preparation have not been reported in the veterinary medical literature.

Although the cost of surgical skin preparations used on dogs has not been directly analyzed, the additional cost incurred as a result of SSIs in dogs and cats has been documented.29,30 In a study31 to assess the cost and quality of 2 hand hygiene regimens, a waterless alcohol-based rinse was found to be significantly less costly, compared with traditional handwashing, because of the reduced time required to complete the procedure; furthermore, it was associated with significantly better hand hygiene quality. Use of a surgical hand rub was equivalent to the use of a surgical hand scrub with regard to prevention of SSIs after clean and clean-contaminated surgery; use of a surgical hand rub also reduced the cost of hand disinfection by 67%.32 In the present study, a total volume of 1,800 mL of CGS2 and 123 mL of ABAHR was each used to prepare 50 skin sites, the cost of which was $10.90 and $9.60, respectively. Use of an ABAHR might be a feasible option for patient skin preparation in locations where there is no access to soap and water or where transportation of a sufficient volume of chlorhexidine gluconate scrub would be challenging and when financial constraints limit the accessibility to a chlorhexidine gluconate scrub.

Results of bacterial culture of the samples collected by use of direct contact plates in the present study were similar to those of studies that used replicate organism detection and counting plates for evaluation of skin antisepsis in humans and dogs.33,34 Tryptic soy agar is a general-purpose agar medium that may be used for the cultivation of fastidious and nonfastidious aerobic and anaerobic microorganisms. Expected microbial growths on tryptic soy agar medium include Bacillus spp, Staphylococcus spp, Aspergillus spp, Candida spp, and Pseudomonas spp.35–37 The most pathogenic bacterium found on canine skin is S pseudintermedius.38 Transient or resident bacteria in canine skin include Bacillus spp, Corynebacterium spp, Escherichia coli, Proteus spp, and Pseudomonas spp.38 A study39 evaluating the hardiness of various Bacillus spp in the face of different concentrations of ethanol revealed that an appropriate concentration of ethanol as a disinfectant for those microbes was 90%. The ABAHR used in the present study contained 80% ethyl alcohol; therefore, it was not surprising that Bacillus spp were grown in cultures of the ABAHR postapplication samples. Chlorhexidine also reportedly has little effect on the germination of bacterial spores,40 and the presence of Bacillus spp in cultures of the postapplication samples was not unexpected. Alternatively, Bacillus organisms may grow easily in our chosen culture medium. These results may also suggest an effectiveness of either treatment in decreasing the load of pathogenic bacteria (eg, Staphylococcus spp) on skin, because the number of CFUs per plate after application of CGS2 or ABAHR was significantly decreased or bacteria were eliminated, compared with findings for the preapplication samples. The higher number of CFUs per plate after either preparation protocol in 3 dogs was likely attributable to culture plate collection error.

The present study was not designed to evaluate the prolonged activity of the ABAHR and its clinical importance as it relates to development of SSIs. Because we wanted to compare the efficacy of an ABAHR with that of CGS2 in regard to immediate postapplication reduction of the bacterial population on the skin of dogs, long-term evaluation was beyond the scope of our objectives; however, the data obtained from this study support further investigations to evaluate the ABAHR as part of a patient skin preparation protocol.

The results of the present study indicated that the ABAHR protocol was as effective at reducing the bacterial population on the skin of dogs as was the CGS2 protocol. The ABAHR rapidly decreased the bacterial load on the skin, was safe to use on patient skin, and could be applied quickly. The clinical importance of these findings is unknown because the incidence of SSIs was not assessed in the study. Future research is needed to determine the incidence of SSIs following use of the ABAHR as a preoperative patient skin preparation.

Acknowledgments

Funded by Lauderdale Veterinary Specialists, Fort Lauderdale, FL 33309. Sterillium rub spray bottles were donated from Medline Industries, Inc. Micrim Labs Inc. processed all contact plates, providing colony counts and bacterial identification.

The authors declare no conflict of interest related to this report.

This abstract was presented at the 14th Annual Scientific Meeting of the Society of Veterinary Soft Tissue Surgery, Santa Barbara, Calif, May 2015.

ABBREVIATIONS

ABAHR

Alcohol-based antiseptic hand rub

CGS2

Chlorhexidine gluconate 2% scrub

SSI

Surgical site infection

Footnotes

a.

Chlorhexidine scrub 2%, Phoenix Pharmaceuticals, Burlingame, Calif.

b.

Sterillium rub, 80% ethyl alcohol, Medline Industries Inc, Mundelein, Ill.

c.

Replicate organism detection and counting, Remel, Lenexa, Kan.

d.

SPSS, version 22.0, IBM Statistics, Armonk, NY.

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Contributor Notes

Dr. Maxwell's present address is Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL 32608.

Drs. Bennett and Mitchell's present address is Department of Veterinary Clinical Sciences and Veterinary Teaching Hospital, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA 70803.

Address correspondence to Dr. Maxwell (Emaxwell@ufl.edu).