Examining properties influencing infectious microbe associations with surfaces of four different thermoplastic radiation therapy masks.

BACKGROUND: Previous testing revealed that four different microbes applied to face-only masks from Civco, Klarity Medical, Orfit, and Qfix demonstrated variation in the number recovered from each mask type after a 1-hour contact time. In all cases, the Orfit mask demonstrated the largest number of recovered microbes suggesting a preference by tested microbes to create associations with this mask type. METHODS: The current study evaluated three physiochemical features of these thermoplastic masks to determine why the Orfit mask encouraged greater microbial associations. Measurements including water contact angle (WCA), surface topography, and available contact area were determined for each mask type, where feasible. RESULTS: The Orfit mask exhibited the greatest difference in each of the 3 evaluated characteristics. Overall, it showed decreased hydrophobicity, increased surface roughness, and increased surface contact area. The WCA of both Orfit (50.8°) and Klarity (95.6°) masks showed decreased hydrophobicity when compared to native PCL (129.97°). CONCLUSION: The Orfit mask's decreased hydrophobicity, increased roughness, and larger surface contact area appears to have contributed to its ability to support a larger number of microbe associations. The decreased hydrophobicity and altered topography of both Klarity and Orfit masks may have been due to their additional antimicrobial coatings.

Novel boronium salt exhibits substantial antibacterial activity when compared to a commercial quaternary ammonium disinfectant.

Commercial disinfectants are routinely used to decontaminate surfaces where microbes are expected and unwelcome. Several disinfectants contain quaternary ammonium salts, or "quats", all being derived from ammonium. Quaternary alkyl dimethyl benzyl ammonium chloride or bromide disinfectants are widely available. These compounds are effective in reducing or eliminating bacteria on contaminated nonporous surfaces. A unique benzyl derived boronium salt with strong detergent action has been developed. It demonstrated 4-8X greater antibacterial activity against 3 different bacteria when compared to an equal concentration of a commercial quant disinfectant solution containing alkyl dimethyl benzyl ammonium chloride and alkyl dimethyl ethylbenzyl ammonium chloride. Antibacterial effectiveness of each agent was determined by the minimum inhibitory concentration (MIC) method.

Two Bacillus isolates recovered from a radiation therapy facility differ greatly in their ability to attach to four immobilization masks.

BACKGROUND: Thermoplastic immobilization masks used during radiation therapy treatment have been shown to harbor several different types of bacteria. Recovered bacteria included Staphylococcus aureus, Enterococcus species, Gram-negative rods, coagulase-negative staphylococci, and several different Bacillus species. Two of the recovered Bacillus bacteria were examined for their ability to attach to and survive over time on patient head-only masks from four different manufacturers. B. halosaccharovorans was recovered from a treatment facility's water bath while B. cereus was recovered from a patient mask in the same facility. Bacillus bacteria were chosen for this study due to their capability to form dormant spores. METHODS: Inoculums containing either B. halosaccharovorans or B. cereus bacteria were seeded onto predesignated areas of each test mask. Masks were subsequently sampled at intervals of 1-h, 1 week, 2 weeks, 3 weeks, and 4 weeks. Recovered bacterial numbers at each sampling interval were determined using the direct plate count method. Spore stains were made of both bacterial isolates and number of detected spores were enumerated. RESULTS: B. halosaccharovorans attached to each mask type after a 1-h contact time at a number 3X greater than B. cereus. B. halosaccharovorans was also recovered at a number 8.5X greater than B. cereus after 4 weeks. Variation was seen in the attachment capability of each bacterium on tested mask types. Both bacilli were recovered from all 4 masks at each sampling interval including week 4. Examination of spore stains of each bacteria demonstrated nearly a 25:1 ratio of B. halosaccharovorans spores over B. cereus. DISCUSSION: The large variation seen between B. halosaccharovorans and B. cereus capability to attach to each of the four tested masks is revealing, especially when it is combined with determined spore numbers. It suggests that spores play a role in mediating their attachment to mask surfaces. Moreover, the recovery of both bacteria from stored masks after 4 weeks indicates a continued presence of dormant spores since growth-supportive nutrients are lacking. It also implies the potential for their transfer to a patient wearing a contaminated mask during a treatment session. CONCLUSION: The demonstrated ability of these two Bacillus bacteria to attach to and reside on patient masks presents a dilemma. Routine cleaning with approved disinfectants may not be sufficient to eliminate dormant spores on masks surfaces. This matter requires further investigation. For now, a small modification to the routine mask cleaning procedure before its application may help to reduce the possibility of spore transfer.

Sampling of Patient Radiation Therapy Thermoplastic Immobilization Forms Reveals Several Types of Attached Bacteria.

BACKGROUND: Thermoplastic medical devices used during patient therapy have been shown to harbor microbes, including those causing healthcare-associated infections (HAI). This issue has not been previously evaluated for immobilization forms used during radiation therapy. The present study addresses this matter by sampling immobilization forms used during patient treatment to see if any microbes could be similarly recovered. METHODS: Twelve head-only in-use patient forms were sampled at 3 radiation therapy facilities. Sampled form areas included cheeks, forehead, and nose. A site survey was also conducted to determine individual form characteristics and form handling procedures. RESULTS: All twelve forms demonstrated at least one type of bacteria being recovered from sampled areas, several forms with multiple types. Bacterium was not recovered from the nose area of a single form, even though bacteria were recovered from the same form's cheeks and forehead areas. Recovered bacteria included Bacillus species spp. (21), coagulase-negative staphylococci or CoNS (19), Staphylococcus aureus (2), Enterococcus species (1), alpha-hemolytic (viridians) streptococci (1), and Gram-negative rods (1). Bacillus species spp. and CoNS were recovered from 10 of 12 (∼84%) forms in at least one sampled area. In addition, a single Bacillus spp. was also recovered from a water bath used to heat forms at one treatment facility. DISCUSSION: The detected presence of several bacterial types on patient forms indicates that they can attach to and surviving, for a time, on form surfaces. Two of the bacteria recovered, namely S. aureus and Enterococcus spp. are confirmed HAI pathogens. The remainder are considered as opportunistic bacterial pathogens that can cause HAIs in debilitated patients. Of special concern is the recovery of several different species of the environmental bacterium Bacillus spp. at a higher level than CoNS, a normal skin bacterium. The ability of Bacillus spp. to form spores further enhances its survival capability on form surfaces. The source of the recovered bacteria, including Bacillus spp. was not determined. CONCLUSION: The presence of bacteria on stored patient form surfaces indicates that there is a real potential to transfer them to the patient during its reapplication. The actual potential for microbe transfer such as Bacillus spp. or its spores has yet to be determined. Consequently, care should be taken by radiation therapy personnel in handling forms during patient reapplication. Precautions such as donning a fresh pair of gloves and cleaning a form with an approved disinfectant can help to reduce and/or eliminate unintended microbe transfer to the patient wearing it. This procedure should also be considered for patients without apparent open or leaking wounds.

Recognition of Naegleriae ameba surface protein epitopes by anti-human CD45 antibodies.

Phagocytosis is a highly conserved mechanism exhibited by both free-living amebas and mammalian blood cells. Similarities demonstrated by either cell type during engulfment of the same bacterial species may imply analogous surface proteins involved in receptor-mediated endocytosis. The increased availability of anti-human leukocyte antibodies or clusters of differentiation (CD) markers used in conjunction with flow cytometric (FCM) and/or immunohistochemical (IHC) analysis provides investigators with a relatively easy method to screen different cell populations for comparable plasma membrane proteins. In this study, we incubated Naegleria and Acanthamoeba amebas with several directly conjugated anti-human leukocyte monoclonal antibodies (mAb) for similarly recognized amebic epitopes. CD marker selection was based upon a recognized role of each mAb in phagocyte activation and/or uptake of bacteria. These included CD14, CD45, and CD206. In FCM, only one CD45 antibody demonstrated strong reactivity with both Naegleria fowleri and Naegleria gruberi that was not expressed in similarly tested Acanthamoeba species. Additional testing of N. gruberi by IHC demonstrated reactivity to a different CD45 antibody. Our results suggest a possible utility of using anti-human leukocyte antibodies to screen amebic cells for similarly expressed protein epitopes. In doing so, several important items must be considered when selecting potential mAbs for testing to increase the probability of a positive result.