University of Pretoria
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Colony forming units on fingertips of final year veterinary students performing an ovariohysterectomy at different time intervals

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journal contribution
posted on 2022-10-12, 10:14 authored by Hermien ViljoenHermien Viljoen

Data for a journal article published on Veterinary Surgery 2022 Vol. 51. no. 3, pp. 47-454.  This was conducted as a randomized field study. Participants eligible for enrolment were final year veterinary students performing elective ovariohysterectomies on client-owned dogs. Participants were required to have nails short (< 1 mm), clean, and free of artificial nails or nail products in conformity with international guidelines concerning surgical hand hygiene. Participants were required to wear appropriate surgical attire including scrubs, gowns, shoe and head covers while performing ovariohysterectomies. Participants were assigned to one of four groups (group A, B, C or D) using a simple random allocation method by drawing a number out of a bag. The different groups represented different hand preparation protocols prior to applying an ABHR for all groups. Standardized instructions were used to prevent variations in technique. 

The following products were used in the hand preparation protocols assigned to students: 1) a hand scrub containing 4% w/v CHX [Medinox®, Johannesburg, South Africa], 2) a hand scrub containing benzalkonium chloride 0.1-1% and polymeric biguanide hydrochloride 0.01-0.1% (BAC) [Health and Hygiene (Pty) Ltd, Florida Hills, South Africa], 3) a pH-neutral, non-medicated soap (pHN) [No name brand, produced by Kyron Laboratories (Pty) Ltd, Benrose, South Africa] and 4) an ABHR antiseptic solution containing 0.5% CHX, 70% propyl alcohol and emollients [B Braun Medical (Pty) Ltd, Randburg, South Africa]. To establish a baseline (sample 1), all participants rinsed their hands and forearms up to their elbows under lukewarm running water for 30 seconds followed by drying their hands and arms completely with non-sterile paper towel. Groups A, B, and C performed a pre-wash by wetting and washing their hands and arms up to their elbows with CHX, BAC or pHN, respectively, for 30 seconds (Sample 2). They subsequently rinsed them under water for a further 30 seconds before drying their hands and arms with non-sterile paper towel so that the total pre-washing procedure lasted one minute. Once the pre-washing was completed, an ABHR was applied according to the manufacturer’s recommendation for surgical hand preparation. Participants assigned to group D did not perform a pre-wash and applied and ABHR following the rinsing step.  The ABHR rubbing procedure continued until the alcohol had completely evaporated, after which sterile surgical gown and closed glove donning was performed according to standardized protocols.

To collect samples, participants gently pressed all the distal aspects of the phalanges of one or both hands on agar contact plates (Oxoid Ltd., Basingstoke, Hampshire, England) for five seconds. Persons assisting with collection of samples decontaminated their hands by performing an ABHR procedure and wore examination gloves to prevent inadvertent contamination during the collection procedure. Packaging of agar contact plates remained sealed just prior to collection of samples and were re-sealed immediate after sample collection to prevent post-sampling contamination. Agar contact plates consisted of tryptone soya agar with neutralizing agents’ lecithin (5%) + Tween 80 (15%). Sample 1 was taken of left and right hands after the rinse step. Sample 2 was taken after participants performed the pre-wash. An online random choice generator ( was used to determine if the second sample was taken from the left or right hand. Sample 2 was not collected from Group D but a left or right hand was identified for the participant. Sample 3 was taken directly after a surgical ABHR procedure from the hand that was not selected in the previous round. To standardize the timing of the final sample (sample 4), 120 minutes was chosen as the time the final sample would be taken as this is typically the time a veterinary student takes to complete an ovariohysterectomy at the training facility. A timer was set for 120 minutes as soon as surgical gowning and gloving were completed. The students proceeded with performing an ovariohysterectomy on client-owned dogs under the supervision of a qualified veterinarian. At the end of 120 ± 5 minutes, students were asked to remove the surgical gloves, and the final sample (sample 4) was taken from the hand that was not sampled in the previous round, all while preserving sterility of the hands. 

Surgical gloves were collected and evaluated for the number of punctures per finger by filling it with colored water and sealing the cuff. The dominant hand of each participant was recorded. Agar contact plates were placed in an incubator for 48 hours at 36 – 38 °C under aerobic conditions within four hours of collection. Samples were labelled in a coded manner so that laboratory staff that counted CFU were blinded to the hand preparation protocol used.  CFU were counted with the naked eye by a laboratory technician. 


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