Alternative methods of blood donor skin disinfection

Authors: Sandra Ramirez-Arcos, PhD, Mariam Taha, PhD, Yuntong Kou, MSc, and Mindy Goldman, MD, FRCPC
 

Abstract

Background and Objectives: At Canadian Blood Services, the primary method of donor skin disinfection is the ChloraPrep One swabstick (2% chlorhexidine and 70% isopropyl alcohol). The aim of this study was to evaluate the efficacy of available, licensed alternative skin disinfection methods for donors sensitive to chlorhexidine. Materials and Methods: In Phase I (127 subjects), ChloraPrep and an alternative swabstick (LORIS 10% povidone-iodine swabstick) were compared. In Phase II (134 subjects), ChloraPrep and a two-step method (10% povidone-iodine swabstick followed by application of an isopropanol swabstick) were compared. Sixty-five mm diameter contact plates were applied to the antecubital fossa on each arm of the subjects for 30 seconds before and after disinfection. Plates were incubated and bacteria quantified by colony counting, then statistical analyses were performed. Results: Phase I: The povidone-iodine swabstick was significantly less effective than Chloroprep (p < 0.0001). Phase II: The two-step method was significantly more effective than the povidone-iodine swabstick (p < 0.0001). Conclusion: Application of 10% povidone-iodine swabstick followed by an isopropanol swabstick was as effective as our current primary skin disinfection method. This two-step method has been selected to replace our current alternative method for donors sensitive to chlorhexidine (70% isopropyl alcohol scrub sponge followed by an ampoule of 2% iodine tincture).

Introduction

Adequate disinfection of the skin at the venipuncture site on a donor’s arm is important to reduce bacterial contamination of blood products for transfusion¹. Skin disinfection practice varies; commonly-used antiseptic agents include iodine, isopropyl alcohol, chlorhexidine or combinations of these, and modes of application include swabs, scrubs, ampoules and applicators^2-4. Although adequate disinfection is important to ensure cleanliness, none of the methods can achieve an absolutely aseptic site¹. Together with diversion of the first portion of a blood donation and use of bacterial contamination testing, skin disinfection has improved the safety of blood^5,6, but some risk of bacterial contamination remains, particularly in platelet products⁷. 

At Canadian Blood Services, the primary skin disinfection method is ChloraPrep One (CareFusion, Mississauga, ON, Canada), a one-step 2% chlorhexidine / 70% alcohol-containing disinfectant. For the approximately 3% of blood donations at Canadian Blood Services from donors who report sensitivity to chlorhexidine, an alternative two-step method using a 70% isopropyl alcohol scrub followed by an ampoule of 2% iodine tincture, also from CareFusion, was used. Both methods were validated in a study conducted in 2008⁴. However, production of this alternative two-step method was suspended in October 2015. Thus there was a need to replace the alternative method to continue to provide adequate skin disinfection for chlorhexidine-sensitive donors and avoid a negative impact on blood product inventory. Currently, the bacterial contamination rate of platelet concentrates at Canadian Blood Services is approximately 0.01% and any new protocol must deliver skin disinfection that is as effective. The purpose of this study was to evaluate available alternative skin disinfection methods that are licensed in Canada and would be suitable for donors who are sensitive to chlorhexidine.

Results

Phase I: A one-step disinfection method with povidone iodine solution was not as effective as ChloraPrep

Pre-disinfection, the number of colonies was equivalent for ChloraPrep and LORIS swabsticks (p = 0.8461; Table 1). There was a significant reduction in the number of colonies between pre- and post-disinfection counts for each method (p < 0.0001; Table 1). However, the number of colonies post-disinfection was significantly lower for ChloraPrep than for LORIS (p < 0.0001, Table 1) indicating that ChloraPrep was significantly more effective at disinfecting the skin of the study subjects.

Table 1. Comparison of colony counts per plate before and after skin disinfection between ChloraPrep and LORIS.

The acceptability of LORIS by both phlebotomists and donors was examined. The application time for LORIS was 2 minutes and it took at least 1.5 minutes to dry for a total time of 3.5 minutes. The swabstick was used according to the manufacturer’s instructions, which required squeezing the swab before application. It was observed that as a result of this, the amount of residual liquid (povidone-iodine) in the swab was not consistent. This was reflected in the large variation in colony count reduction among subjects. Phlebotomists reported that the application of the swabstick caused ergonomic concerns since the up and down motion required for swab application caused discomfort in their shoulders. Finally, a few subjects (<10) reported that the swabstick was abrasive and caused irritation.

Phase II: A two-step disinfection method with povidone-iodine and isopropyl alcohol was more effective than a one-step disinfection method with povidone iodine solution

When ChloraPrep and the two-step method (povidone-iodine and isopropyl alcohol) were compared, there was a significant reduction in the number of colonies between pre- and post-disinfection counts for each method (p < 0.0001; Table 2). Although the number of colonies post-disinfection was significantly lower for ChloraPrep than for the two-step method (p < 0.0001, Table 2), showing higher effectiveness, the number of colonies in pre-disinfection plating was significantly different between the two methods (p = 0.0072). Therefore, the initial (pre-disinfection) number of colonies was normalized, and the reduction in the log10 bacteria counts for each method was calculated. This analysis showed that ChloraPrep and the two-step method were comparable in skin disinfection effectiveness (p = 0.9999). Interestingly, a similar analysis was conducted to compare ChloraPrep and LORIS, which also showed no statistical difference in effectiveness when the pre-disinfection number of colonies was normalized (p = 0.2891), contradicting the results shown in Table 1.

Table 2. Comparison of colony counts per plate before and after skin disinfection between ChloraPrep and the two-step method. 

As this statistical analysis was not reflecting the superior effectiveness of LORIS over ChloraPrep, it was then decided to do a non-paired comparison of LORIS and the two-step method. This analysis showed that the pre-disinfection number of colonies was equivalent for both methods (p = 0.5885; Table 3). There was a significantly higher reduction in the post-disinfection number of colonies for the two-step method than for LORIS (p < 0.0001; Table 3). These results conclusively indicate that the two-step method is more effective at disinfecting the skin of the study subjects than LORIS.

Table 3. Comparison of colony counts per plate before and after skin disinfection between LORIS and the two-step method. 

Using the two-step method, the application time of Aplicare was 1 minute and it took 1 minute to dry. The application time of Dynarex was 1 minute and it dried in approximately 30 sec, for a total time of 3.5 minutes. The acceptability of the two-step method was overall better than that for LORIS. There was no need to squeeze the swabs before application and therefore the amount of residual liquid (povidone-iodine and isopropyl alcohol) in the swabs was comparable. Due to the circular movement during application of the swabsticks, no ergonomic concerns were reported by the phlebotomists. There were no reports of skin irritation from the participant subjects.

Discussion

Bacterial contamination of blood products, particularly platelets, can lead to severe transfusion reactions [8] and, in rare cases, fatalities^9,10. Inadequate skin disinfection has been implicated as the cause of contamination in certain cases¹¹ and thus it is critical that skin is sufficiently disinfected to minimize the risk of contamination. Skin sensitivities need to be considered when choosing a disinfecting agent. At Canadian Blood Services, phlebotomists wear gloves while disinfecting donors’ arms and so our main concern lies with donor skin sensitivities. Chlorhexidine-based disinfectants are widely used and are the preferred disinfection agent for donors who are sensitive to iodine¹. ChloraPrep One is the primary method for skin disinfection at Canadian Blood Services⁴ and elsewhere¹². Until recently, an isopropyl alcohol/iodine-based skin disinfection method was used at Canadian Blood Services for the approximately 3% of donations from donors who report sensitivity to chlorhexidine. When this method was discontinued in October 2015, we examined the efficacy of two alternative methods for skin disinfection to ensure continuing service for chlorhexidine-sensitive donors. This study showed that the two-step iodine/isopropyl alcohol method was as effective as our primary disinfection method (ChloraPrep One). Donors sensitive to both chlorhexidine and iodine are deferred as there is no effective disinfection method available.

Many blood clinics choose to use a one-step method as it is simpler and more efficient, and in our earlier study we did not find significant differences in effectiveness between comparable one-step and two-step methods⁴. Benjamin et al., who examined apheresis platelet donations, found that skin disinfection with a single-step 2% chlorhexidine swab was more effective than a two-step povidone-iodine method in preventing bacterial contamination¹³. However, another study examining skin disinfection methods found that a two-step 10% povidone-iodine technique was an effective disinfectant¹⁴. 

The need for blood donors is constant in order to maintain an appropriate blood supply for Canadian patients. It is important to accommodate as many donors as possible. This study was necessary to address the concerns of chlorhexidine-sensitive donors and ensure their continued contribution to the blood supply while maintaining the safety of the system. This study was limited to an examination of just two alternative skin disinfection methods. However, this was sufficient to identify a viable chlorhexidine-free method. The two-step Aplicare plus Dynarex method was more effective than the 10% povidone-iodine swabstick, and the phlebotomists and study participants reported that the two-step method was acceptable. In contrast, the phlebotomists and study participants reported problems with the 10% povidone-iodine swabstick and it was less effective than ChloraPrep One in disinfecting the donors’ skin. The two-step method was therefore implemented at Canadian Blood Services in the fall of 2015 replacing our previous method for donors sensitive to chlorhexidine (70% isopropyl alcohol scrub sponge followed by an ampoule of 2% iodine tincture).

Materials and Methods

Study design and subjects

Ethical approval for this study was granted by the Canadian Blood Services Research Ethics Board. Members of staff at Canadian Blood Services head office in Ottawa, ON, Canada were recruited as participants for this study, which was conducted in two phases. In Phase I, 127 subjects were recruited and in Phase II, 134 subjects were recruited. In each phase, a paired comparison of two disinfection methods was conducted using both arms of each study subject. All subjects provided informed consent prior to participation and some individuals participated in both phases of the study.

Disinfection procedures

In Phase I, the left arm was disinfected with the ChloraPrep One swabstick (CareFusion, Mississauga, ON, Canada), which contains 2% w/v chlorhexidine gluconate and 70% v/v isopropyl alcohol. The right arm was disinfected with the LORIS povidone-iodine swabstick (Lernapharm Inc., St-Laurent, Québec, Canada), which contains 10% w/v povidone iodine solution, USP, equivalent to 1% available iodine. Each method was applied according to its manufacturer’s instructions. In Phase II, the left arm was disinfected with the ChloraPrep swabstick and the right arm was disinfected with a two-step method:  the Aplicare 10% povidone-iodine USP swabstick (1% available iodine, from Clorox Healthcare, Oakland, CA) followed by a 70% isopropyl alcohol swabstick (Dynarex Corporation, Orangeburg, NY). Phlebotomists were asked to report on their experience using each of the alternative methods. Subjects were asked if they experienced discomfort with any of the methods used, and responses were noted. Subjects were also asked to contact the study coordinator if any discomfort or rash was noted after the study.

Assessment of disinfection efficacy

The efficacy of disinfection was evaluated using 65 mm diameter contact plates containing agents for neutralization of remaining disinfectants (Remel tryptic soy agar with lecithin and polysorbate 80; Oxoid Inc., Nepean, ON, Canada or BBL D/E Neutralizing Agar; BD, Sparks, MD, USA). Contact-plate cultures were done on the antecubital fossa on each arm of the subjects for 30 seconds before and after disinfection. Within 3 hours, contact plates were placed in a 37°C incubator. Plates were incubated for 24 hours and colonies were counted.

Statistical analysis

The number of subjects recruited for each phase ensured detection of a difference of 10% in efficacy between methods (80% power, significance level 5%). A paired comparison was made of the colony counts on both arms of the same donor, using paired Wilcoxon’s Signed-rank test.  A non-paired comparison was made of the colony counts on arms of different donors, using non-paired Wilcoxon’s Signed-rank test. Significance was accepted at p < 0.05.

Acknowledgements

The authors acknowledge Dr. Qi-Long Yi, Canadian Blood Services biostatistician, who performed the statistical analyses. The authors thank Canadian Blood Services head office staff in Ottawa, ON, Canada for their participation in this study. The authors are grateful to Ms. Adriana Zapata, Canadian Blood Services research helper, for technical assistance and the nurses involved in the coordination of skin disinfection kit shipments and application of the disinfectants. The authors acknowledge Drs. Geraldine Walsh, Kendra Hodgkinson, and Sophie Chargé from the Centre for Innovation, Canadian Blood Services, for their editorial support during the writing of this manuscript.

Sources of funding: This research received financial support from Canadian Blood Services (Product and Process Development program), funded by the federal government (Health Canada) and provincial and territorial ministries of health. The views herein do not reflect the views of the federal, provincial, or territorial governments of Canada.

Conflicts of interest: The authors have no conflicts of interest to disclose.

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