Persistence of microbial contamination on transvaginal ultrasound probes despite low-level disinfection procedure.
OBJECTIVE
In 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.


METHODS
Samples 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.


RESULTS
A 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.


CONCLUSIONS
Our 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.
Université Bordeaux Segalen, Microbiologie Fondamentale et Pathogénicité Unité Mixte de Recherche 5234, Bordeaux, France.
Fatima
F
M'Zali
Université Bordeaux Segalen, Microbiologie Fondamentale et Pathogénicité Unité Mixte de Recherche 5234, Bordeaux, France.
Carole
C
Bounizra
Centre Hospitalier Universitaire de Nîmes, Service de Biostatistique, Epidémiologie Clinique, Santé Publique, Informatique Médicale, Nîmes, France.
Sandrine
S
Leroy
Laboratoire de Virologie, Centre de Biologie et Pathologie Est, Hospices Civils de Lyon, Lyon, France.
Yahia
Y
Mekki
Université Bordeaux Segalen, Microbiologie Fondamentale et Pathogénicité Unité Mixte de Recherche 5234, Bordeaux, France.
Claudine
C
Quentin-Noury
Université Bordeaux Segalen, Microbiologie Fondamentale et Pathogénicité Unité Mixte de Recherche 5234, Bordeaux, France.
Michael
M
Kann
D001419:Bacteria / Q000187:drug effects / Q000235:genetics; D003428:Cross Infection / Q000382:microbiology / Q000517:prevention & control / Q000821:virology; D004202:Disinfectants / Q000494:pharmacology; D004203:Disinfection / Q000379:methods; D004866:Equipment Contamination / Q000517:prevention & control*; D005658:Fungi / Q000187:drug effects / Q000235:genetics; D006801:Humans; D009174:Mycoplasma / Q000187:drug effects / Q000235:genetics; D027383:Papillomaviridae / Q000187:drug effects / Q000235:genetics; D016133:Polymerase Chain Reaction / Q000379:methods
D004202:Disinfectants