Microbiologic Alterations of the Conjunctiva of Hot Tub-soaking Ophthalmologists (MACHO)

The purpose of this study is to determine if there are microbiologic alterations of the ocular surface after hot tub exposure. The study will evaluate the number of microbes before and after hot tub use in order to find out whether hot tub exposure has any change on the organisms present on the ocular surface. Participants will be randomized to dunk or not to dunk their head during their time in the hot tub.

Study Overview

• Status: Completed
• Conditions: Conjunctivitis, Bacterial; Keratitis Bacterial
• Intervention / Treatment: Behavioral: Dunk; Other: Exposure to Hot Tub

Detailed Description

Keratitis is a rare destructive cause of blindness. It typically affects young and healthy individuals, is excruciatingly painful, and difficult to treat. With 60% of cases mis-diagnosed at presentation, acanthamoeba keratitis carries a far worse visual prognosis compared to other cornea infections. Exposure to hot tubs is a widely accepted risk factor. However, the mechanism of infection and prediction of who is at risk is unknown as the vast majority of hot tub users do not become infected.In vivo changes to ocular microbiology after hot tub exposure has never been described.

Changes to ocular microbiology after exposure to hot tubs have not been described. The purpose of this study is to investigate whether there are significant alterations in the microbiology of the conjunctiva after hot tub exposure that may contribute to these changes.

This study will recruit at least 34 subjects, who will be randomized to head submersion versus no head submersion, using at least three different hot tubs. A conjunctival swab, a minimal-risk test performed routinely in the eye clinic, will be performed before and after 15 minutes of hot tub exposure on one eye (randomized) per subject. The swabs will be plated on blood agar (bacterial cultures) and non-nutrient agar (acanthamoeba cultures).

In this prospective study, healthy subjects will be recruited. The study will be Health Insurance Portability and Accountability Act compliant and approved by the Institutional Review Board. All subjects will review and sign an informed consent form.

Each patient will have the conjunctiva of one eye (randomized) cultured. This practically no-risk technique entails touching a polyester-tip swab to the lining of the lower eyelid. Each subject will be randomized to head submersion or no head submersion; this exposure will be masked by the study coordinator. After 15 minutes of hot tub exposure, the subject will have the same eye swabbed for cultures.

Each sample (pre- and post-hot tub) will be randomly assigned a study number. One study coordinator will record and mask data. Water from each tub will be cultured.

The culture plates will be sent to our microbiology facility at UCSF and identification of organisms on the blood agar plates will be performed on our MALDI (mass spectrometry to identify bacteria and fungi). Non-nutrient agar plates will be plated with E. coli overlay and incubated for up to 7 days. The plates will be randomized and the microbiologists will be masked to exposures.

• Study Type: Interventional
• Enrollment (Actual): 36
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • California
    • San Francisco, California, United States, 94122
      • UCSF

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: Yes
• Genders Eligible for Study: All

Description

Inclusion criteria:

• greater of 18 years of age
• a willing participant
• healthy

Exclusion criteria:

• pregnancy
• high or low blood pressure
• active diarrhea
• lymphedema
• heart disease
• seizure disorder.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Double

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Head Dunk; Subjects who are assigned to be in this arm are asked to sit in a hot tub for 15 minutes and instructed to submerge his or her head in the hot tub at least once and at least up to the eyebrows during his or her time in the hot tub.	Behavioral: Dunk; If randomized to "Dunk," the subject is asked to submerge his or her head in the hot tub at least up to brow level.; Other: Exposure to Hot Tub; Subjects will be asked to sit in a hot tub for 15 minutes (with an individual timer).
Placebo Comparator: No Head Dunk; Subjects assigned to this arm are asked to sit in a hot tub for 15 minutes but to keep his or her chin above water during the entire time.	Other: Exposure to Hot Tub; Subjects will be asked to sit in a hot tub for 15 minutes (with an individual timer).

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Quantity of organisms	Genus-species will be identified for each sample, and quantified with an ordinal scale (0-4). The total of this score will be the quantity for that person-time. The primary analyses will be a Wilcoxon Rank Sum test (Mann-Whitney) between the two arms at the follow-up time point (randomized comparison of dunk vs no-dunk), and a Wilcoxon Signed Rank test between pre-hot-tub and post-hot-tub (longitudinal comparison of all cases). We estimate that a total of 20 subjects will provide 80% power to detect a 1.25 SD difference in the total quantity score between randomization arms at the post (f/u) time point. We estimate 80% power to detect a .9 SD difference between pre (baseline) and post (f/u) time points in a paired longitudinal analysis.	1 year

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Richness (number of species per sample) of organisms found in the conjunctiva with hot tub use (post-test comparison)	The investigators will assess whether organism diversity (richness) changes between arms (post-test comparison) using Simpson's Diversity, expressed in units of effective number (see Jost). We will also assess using Shannon's Diversity.	1 year
Richness (number of species per sample) of organisms found in the conjunctiva with hot tub use (pre versus post)	The investigators will assess whether organism diversity (richness) changes longitudinally (pre vs post-test comparison).	1 year
Difference in organism profile with hot tub use (pre versus post)	The investigators will determine whether the organism profile differs longitudinally (pre vs post-test comparison) using L-2 norm (Euclidean distance) and PERMANOVA. We will also assess using L-1 norm (Manhattan distance)	1 year
Difference in organism profile with hot tub use (between arms)	The investigators will determine whether the organism profile differs between arms (post-test comparison) using L-2 norm (Euclidean distance) and PERMANOVA. We will also assess using L-1 norm (Manhattan distance)	1 year
Quantity comparing pre-hot tub and post-hot tub swabs	We will compare quantity of organisms (amount and type) before and after hot tub use in both arms. We will used a paired t-test for analysis.	1 year
Specific organisms found in the conjunctiva with hot tub use	The investigators will compare specific organisms (Staphylococcus epidermidis, Corynebacterium species) between arms (post-test only) and longitudinally between time points (pre vs post-test) with Bonferroni correction	1 year

Collaborators and Investigators

• Sponsor: University of California, San Francisco
• Investigators: Principal Investigator: Gerami D Seitzman, MD, UCSF/Proctor Foundation

Study record dates

Study Major Dates

• Study Start (Actual): May 27, 2019
• Primary Completion (Actual): March 26, 2020
• Study Completion (Actual): March 26, 2020

Study Registration Dates

• First Submitted: June 5, 2019
• First Submitted That Met QC Criteria: June 13, 2019
• First Posted (Actual): June 14, 2019

Study Record Updates

• Last Update Posted (Actual): September 10, 2020
• Last Update Submitted That Met QC Criteria: September 2, 2020
• Last Verified: September 1, 2020

More Information

Terms related to this study

• Keywords: bacterial keratitis; hot tub; conjunctival cultures
• Additional Relevant MeSH Terms: Infections; Eye Diseases; Bacterial Infections; Bacterial Infections and Mycoses; Conjunctival Diseases; Corneal Diseases; Eye Infections, Bacterial; Eye Infections; Keratitis; Conjunctivitis; Conjunctivitis, Bacterial
• Other Study ID Numbers: 18-26141

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No