Infection Control & Hospital Epidemiology
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Table 2. Mean Number of Staphylococcus aureus Dry Surface Biofilm Cells Transferred During 19 Touches, by 3 Types of Commonly Used Gloves (n=12 gloves per type)
Untreated
Glove Type Nitrile gloves Latex gloves
Surgical gloves Detergent Treated
Mean CFU Transferred (Log10) ± SD (n=12) Transfer Rate, % Mean CFU Transferred (Log10) ± SD (n=12) Transfer Rate, % 2.90 ± 0.12 2.50 ± 0.60 3.02 ± 0.30
0.0103 0.0041 0.0137
Note. CFU, colony-forming units; SD, standard deviation.
low transfer rate of pathogens, but latex allergy limits their use. The restricted use of latex gloves in the healthcare environment limits the current study. Further work is needed to develop allergy-free latex gloves (or similar material) for reduced trans- mission of pathogens without allergy. Our results for latex gloves are consistent with the study by Moore et al,22 in which trans- mission of planktonic MRSA by various types of gloves was measured. Latex gloves transmitted the least number of MRSA from and to fomites. In the present study, DSB was treated with 5% neutral deter-
Fig. 3. Number of colony-forming units (CFU) of bacterial cells transmitted from untreated S. aureus dry-surface biofilm (DSB) per touch. Black horizontal line in the graph indicates the infective dose (15 cells/cm2 or 1.18 logs/cm2).
gent for 5 seconds to mimic wetting of surfaces during hospital cleaning. We hypothesized that surfactants within the detergent ensure that moisture is readily absorbed into the biofilm struc- ture, which changes the semi-dried biofilm’s physiochemical properties to a hydrated type, increasing cell detachment and resulting in a high transfer rate. The use of 5% neutral detergent to mimic basic hospital
Fig. 4. Number of colony-forming units (CFU) of dry-surface biofilm (DSB) bacterial cells transmitted from treated Staphylococcus aureus DSB with the number of touches. The infective dose is 15 cells/cm2 1.18 logs/cm2.
detachment of
cells sticking to the recipient surface.40 Surface factors such as hydrophobicity and roughness affect adhesion and hence the attachment/transmission of bacteria. Hydrophilic bacterial cells attach more efficiently to hydrophilic surfaces and vice versa. Staphylococcus aureus being hydrophilic atta- ches readily to hydrophilic surfaces compared to hydrophobic surfaces.41 The 3 glove types, namely nitrile, latex, and surgical gloves,
cellsfromthe donorisfollowedbythese
were nonporous and had smooth surfaces visually. The surgical glove was the most hydrophilic of the 3 gloves and transferred the greatest number of bacteria from the DSB to the microbiological media. In contrast, latex gloves, being the most hydrophobic transmitted the least number of bacteria from DSB irrespective of whether the DSB had been touched dry or treated with detergent. Hence latex gloves are the most suitable for use in the hospital environment from an infection control point of view, due to their
cleaning without disinfectants and scrubbing action is also a study limitation, although many hospital surfaces worldwide are not routinely disinfected. Hospital cleaning using detergent with and without disinfectants is debatable due to their potential chemical health hazards. Recent studies have shown that the DSB is even more tolerant to biocide action. Hence, we mimicked the ‘basic’ hospital cleaning protocol of 5% detergent soak in our study, excluding scrubbing because all surfaces are not scrubbed while cleaning. However, further scientific studies can be designed using common disinfectants or single-wipe action with detergent/dis- infectant wipes42 to test bacterial transmission after absolute effective biofilm cleaning. In conclusion, although the bacteria incorporated into DSB are
attached to a surface and each other, they are readily transferred to new surfaces by gloved hands. The number of bacteria trans- ferred increases when the DSB is exposed to detergent, even for a short time. This finding suggests that removal of DSB as well as planktonic environmental contamination need to be addressed to ensure a safe hospital environment.
Acknowledgments. This study was funded by an Australian Research Council Linkage Projects Scheme LP130100572 in conjunction with Whiteley Corporation. Karen Vickery was in receipt of a Macquarie University Vice Chancellor Innovation Fellowship. Dr Shamaila Tahir was in receipt of Aus- tralian Postgraduate Award.
Financial support. This study was funded by an Australian Research Council Linkage Projects Scheme (grant no. LP130100572) in conjunction with Whiteley Corporation. Karen Vickery received a Macquarie University Vice Chancellor Innovation Fellowship. Durdana Chowdhury received a Macquarie University International Postgraduate Scholarship.
Conflicts of interest. Greg Whiteley is the Managing Director and Trevor Glasbey is the Research and Development Manager of Whiteley Corporation,
3.76 ± 0.66 2.99 ± 0.08 3.74 ± 0.69
0.0741 0.0126 0.0705
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