NEHA October 2023 Journal of Environmental Health

ADVANCEMENT OF THE SCIENCE

TABLE 1

Survival and Persistence of Phi 6 on Hotel Guest Room Surfaces

Day

Mean and Standard Deviation of Log PFU/cm 2 for Each Surface a

Bed

Carpet

Desk

Light Switch

Door Handle

Remote Control 3.5 ± 0.3 2.0 ± 0.3 1.4 ± 0.3 0.9 ± 0.3

Room Curtain 2.5 ± 0.4 1.2 ± 0.2

Hotel Amenities 3.1 ± 0.9 1.9 ± 0.4 1.0 ± 0.3 0.5 ± 0.2

Leather

Bathroom Faucet 3.8 ± 0.3 2.5 ± 0.2 1.3 ± 0.1 0.9 ± 0.4 0.4 ± 0.2

1 2 3 4 7

3.5 ± 0.2 2.2 ± 0.3 1.1 ± 0.4

3.0 ± 0.4 1.5 ± 0.1 0.5 ± 0.3

3.3 ± 0.6 2.0 ± 0.4 1.3 ± 0.1

3.2 ± 0.2 1.9 ± 0.4 1.3 ± 0.3 1.0 ± 0.1

3.8 ± 0.2 2.2 ± 0.3 1.4 ± 0.1 0.7 ± 0.2 ND ± 0.1

2.8 ± 0.5 1.3 ± 0.1 0.4 ± 0.2

ND ± 0 ND ± 0 ND ± 0 ND ± 0 ND ± 0 ND ± 0 ND ± 0 ND ± 0 ND ± 0 ND ± 0 ND ± 0

ND ± 0 ND ± 0 ND ± 0 ND ± 0 ND ± 0 ND ± 0 ND ± 0 ND ± 0 ND ± 0 ND ± 0

0.7 ± 0 ND ± 0 ND ± 0 ND ± 0 ND ± 0 ND ± 0 ND ± 0 ND ± 0 ND ± 0 ND ± 0

ND ± 0 ND ± 0 ND ± 0 ND ± 0 ND ± 0 ND ± 0 ND ± 0 ND ± 0 ND ± 0 ND ± 0

ND ± 0 ND ± 0 ND ± 0 ND ± 0 ND ± 0 ND ± 0 ND ± 0 ND ± 0 ND ± 0

10 13 16 19 22 25 28 30

ND ± 0 ND ± 0 ND ± 0 ND ± 0 ND ± 0 ND ± 0 ND ± 0 ND ± 0

a Mean and standard deviation of phi 6 survival on each hotel guest room surface over 30 days ( N = 6). Note. The greatest reduction of phi 6 occurred within the first 2 days postinoculation. ND = none detected.

After incubation, plates were counted and plaques were recorded as PFU/cm 2 . The above sample plating procedures were carried out on days 1, 2, 3, 4, 7, 10, 13, 16, 19, 22, 25, 28, and 30 for each of the three biological replicates and under similar experimental conditions. Simulation Study A simulation experiment was carried out to determine the ability of phi 6 to transfer from contaminated hands to hotel room surfaces and identify potential cross-contamination from contaminated hotel room surfaces (fomites) to hands. Two dierent scenarios were done using high and low phi 6 concen- trations (high level = approximately 10 7 PFU/ ml; low level = approximately 10 3 PFU/ml) in two experimental settings, three biologi- cal replicates, and with duplicate samples for each replicate. Scenario 1: Cross-Contamination From Inoculated Hands With High or Low Level Phi 6 to Hotel Room Surfaces In the first scenario, hands were inoculated with 0.2 ml of the phi 6 suspension (10 7 PFU/ ml or 10 3 PFU/ml) and held at room tempera-

ture (23 ± 2 °C) for 30 min to dry to facilitate attachment. The investigator used the contami- nated hand to touch for 20 s each coupon sur- face: bed, carpet, hotel amenities, light switch, door handle, TV remote control, room curtain, leather, bathroom faucet, and stainless-steel coupons. Next, each coupon was placed in a stomacher bag and mixed for 2 min. Each item then underwent microbiological analysis. Scenario 2: Cross-Contamination From Inoculated Hotel Room Surfaces With High or Low Level Phi 6 to Hands For the second scenario, each hotel room surface was inoculated with 0.2 ml of phi 6 suspension (10 7 PFU/ml or 10 3 PFU/ml). The items were left to dry for 1 hr. During the drying time, hands were washed for 30 s using soap and warm water (40 °C). The washed hands were dried using paper towels, sprayed with 70% ethanol, and allowed to air dry. Next, the index finger (primary transfer) of each hand touched the contaminated hotel room surfaces for 20 s. Samples from the hands were collected using the glove-juice method (Larson et al., 1980; Sirsat et al., 2013) with brief modifica-

tions as detailed. The index finger from each hand touched the contaminated surfaces for 20 s, and then the hand was inserted into a sterile surgical glove containing 1 ml of ster- ile 0.02% PBST virus buer in the index fin- ger section. The hand with a glove on was vortexed for 60 s. The sample was then trans- ferred from the glove index finger region to a sterile 10-ml conical tube using a sterile pipette. The sample underwent further dilu- tion and viability plate count analyses. For both scenarios, the viability assay was performed by adding 1 ml from each collected sample (either after contaminated hands touched clean hotel room surfaces or clean hands touched contaminated hotel room surfaces), and a 100 µl of overnight host was added to a tube containing 3 ml of soft TSA, shaken by hand, and quickly poured onto TSA plates. The plates were allowed to solidify and then incubated for 24 hr at 22 °C. After incubation, the plaques were counted and recorded as PFU/cm 2 . Statistical Analyses The plaque-forming units from all experiments (persistence and simulation) were converted to

Volume 86 • Number 3