High-level disinfection
pumilus was present in the highest amounts, 3.8 log CFU, followed by 3.7 log CFU of Bacillus safensis (Table 2). Micrococcus luteus and Pseudomonas
luteola were present at lower numbers 2.4 log CFU (Table 2). Microbes (Staphylococcus capitis) were grown from only one probe after UVC treatment. This may have been due to contamination of the probe after treatment. To check whether the bacterial strain was susceptible to UVC treatment, a probe and glass slides were contaminated with the strain in the laboratory and then treated with the Lumicare system. Like other bacteria, the UVC system reduced the numbers of S. capitis on the probes and slides to below the detection limits. The UVC system produced 3.13 log killing on the probes and 4.02 log on glass slides.
Conclusions The researchers summarised that the high-level disinfection UVC system was highly antimicrobial against various vaginal microbes. The system was able to disinfect the probes and reduce the number of bacteria on 93% of probes (only one probe had microbes – S. capitis – cultured after the UVC disinfection cycle) by more than 3.8 log CFU. For the strain of S. capitis isolated from the one probe after UVC disinfection, in laboratory studies this strain was reduced to below detectable limits (>3.13 log reduction) on the
Sample
Sample 1 Sample 5
Sample 9 Sample 14 Sample 15 Sample 16
Sample 17 Sample 18 Sample 19
Sample 20 Sample 21 Sample 22 Sample 25 Sample 28 Sample 30
Untreated control sides Numbers Bacterial type
Staphlococcus warneri Micrococcus luteus Bacillus infantis Bacillus pumilus
Micrococcus luteus Bacillus pumilus
Straphlococcus cohnii Bacillus oceanisediminis Micrococcus luteus Bacillus pumilus Bacillus idriences Bacillus pumilus Bacillus safensis Bacillus pumilus
Bacillus licheniformis Pseudomonas luteola Bacillus pumilus
Pseudomonas luteola Bacillus pumilus Bacillus pumilus Bacillus safensis Bacillus safensis Bacillus pumilus
Numbers (Log10
400 (2.6) 580 (2.8) 4300 (3.6) 4300 (3.6) 2200 (3.3) 460 (2.7) 2100 (3.3) 1700 (3.2) 240 (2.4) 1900 (3.3) 1540 (3.2) 6020 (3.8) 1800 (3.3) 1760 (3.2) 2200 (3.3) 240 (2.4)
4000 (3.6) 6000 (3.8) 3000 (3.5) 6020 (3.8) 4500 (3.7) 240 (2.4)
4400 (3.6) CFU)
- - - - - - - -
- - - - - - - - - - - - -
Staphylococcus capitis
Untreated control sides Total
30
Contaminated 15
UVC treated sides Total
30
Contaminated 0
Table 1: Total number of samples (untreated control and UVC treated) positive for bacterial growth.
50 40 30 20 10 0
50
3.3 Untreated control
probe and glass slides. This most likely indicates that the S. capitis was a contaminant introduced after UVC treatment. They concluded that the predominance
of bacteria of the Bacillus genus probably indicated that the transvaginal probes were not contaminated during use, as these bacteria are not part of the normal vaginal microbiota, which is usually composed of members of
UVC treated side Bacterial type
P value
Numbers (Log10 0
0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0
720 (2.9)
Table: 2 Numbers of bacteria identified on untreated control and UVC treated probes (data from Yasir and Willcox, 2024)
74
www.clinicalservicesjournal.com I November 2024 CFU) p<0.001 UVC treated Figure: 2 Percentage (%) of untreated control and UVC treated probes contaminated with bacteria.
the Lactobacillus genus as well as genera Gardnerella, Prevotella, Atopobium, Sneathia, Megasphaera and Peptoniphilus.7
Bacillus sp.
are more commonly associated with air, soil or water. This suggested that the ultrasound probes were contaminated outside of the body. However, the researchers noted that this may be associated with the human gut8
, suggesting
some faecal contamination during use. Ultimately, guidelines from the British Medical
Ultrasound Society (BMUS) and The Society & College of Radiographers (2020) state that using a cover on the transducer is not in itself an effective method of preventing contamination, as covers may have holes or contamination can occur when removing the covers or via a contaminated glove. They assert that best practice is the use of an automated system.9 Furthermore, guidance produced by a working group of the Healthcare Infection Society also asserts that automated disinfection constitutes best practice. It adds that intracavity devices can be expensive and delicate. Their expense limits the number of devices that a healthcare provider has, which in turn leads to the requirement for a rapid decontamination procedure to reduce the delay between sequential uses. In addition, there should be a documentation system that allows tracking and tracing of each probe to the patients it is used on and each episode of its decontamination.10 The latest research from the University of
New South Wales adds to the growing body of evidence to support the use of UVC in HLD of ultrasound probes. The use of automated high- level disinfection UVC systems can help reduce the risk of healthcare-associated infection arising from ultrasound procedures.
CSJ
% samples contamination
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