Persistence of Microbial Contamination on Transvaginal Ultrasound Probes despite Low-Level Disinfection Procedure

Fatima M'Zali,Sandrine Leroy,Michael Kann,Yahia Mekki,Carole Bounizra,Claudine Quentin-Noury,Rui Medeiros

doi:10.1371/journal.pone.0093368

Abstract

Aim of the StudyIn many countries, Low Level Disinfection (LLD) of covered transvaginal ultrasound probes is recommended between patients' examinations. The aim of this study was to evaluate the antimicrobial efficacy of LLD under routine conditions on a range of microorganisms.Materials and MethodsSamples were taken over a six month period in a private French Radiology Center. 300 specimens derived from endovaginal ultrasound probes were analyzed after disinfection of the probe with wipes impregnated with a quaternary ammonium compound and chlorhexidine. Human papillomavirus (HPV) was sought in the first set of s100 samples, Chlamydia trachomatis and mycoplasmas were searched in the second set of 100 samples, bacteria and fungi in the third 100 set samples. HPV, C. trachomatis and mycoplasmas were detected by PCR amplification. PCR positive samples were subjected to a nuclease treatment before an additional PCR assay to assess the likely viable microorganisms. Bacteria and fungi were investigated by conventional methods.ResultsA substantial persistence of microorganisms was observed on the disinfected probes: HPV DNA was found on 13% of the samples and 7% in nuclease-resistant form. C. trachomatis DNA was detected on 20% of the probes by primary PCR but only 2% after nuclease treatment, while mycoplasma DNA was amplified in 8% and 4%, respectively. Commensal and/or environmental bacterial flora was present on 86% of the probes, occasionally in mixed culture, and at various levels (10->3000 CFU/probe); Staphylococcus aureus was cultured from 4% of the probes (10-560 CFU/probe). No fungi were isolated.ConclusionOur findings raise concerns about the efficacy of impregnated towels as a sole mean for disinfection of ultrasound probes. Although the ultrasound probes are used with disposable covers, our results highlight the potential risk of cross contamination between patients during ultrasound examination and emphasize the need for reviewing the disinfection procedure.

Highlights

Endovaginal ultrasonography is commonly used in gynecology and obstetrics for investigation of suspected disease and pregnancy complications and for medically assisted procreation
Commensal and/or environmental bacterial flora was present on 86% of the probes, occasionally in mixed culture, and at various levels (10-. 3000 colony forming units (CFU)/probe); Staphylococcus aureus was cultured from 4% of the probes (10-560 CFU/probe)
The results of this study revealed that despite Level Disinfection (LLD), the ultrasound probes remained substantially contaminated by clinically significant microorganisms, including Human papillomavirus (HPV), C. trachomatis, mycoplasmas, Gram-positive and Gram-negative bacteria

Summary

Introduction

Endovaginal ultrasonography is commonly used in gynecology and obstetrics for investigation of suspected disease and pregnancy complications and for medically assisted procreation. HLD technologies consist of immersion in glutaraldehyde, hydrogen peroxide, or peracetic acid, and rinsing and drying They present many drawbacks such as possible deterioration of the transducer, chemical damage to the mucosa of patients and practitioners, toxic effects on the gametes and embryos, impaired imaging, and in all cases the time devoted to the procedure. Current practice compliance with this standard is poorly followed [3,4] For this reason, other countries recommend a Low-Level Disinfection (LLD) procedure based on probe wiping with a single use towel (pre)impregnated with products such as quaternary ammonium compounds or phenolics [5]. None, to our knowledge, has investigated contamination of vaginal ultrasound probes by both viruses and bacteria, including Chlamydia trachomatis and mycoplasmas, together with fungi

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