This study shows that gloved hands are capable of transferring organisms from DSB as they touch other surfaces . That is significant because if you are cleaning a patient ’ s room and you ’ re touching the environment with gloved hands , you think that you ’ re protecting yourself by wearing gloves and protecting the patient by cleaning the room , but the reality is that gloves can also transfer those organisms , especially if they haven ’ t been properly cleaned and disinfected .” the nutrients , and so they break off either as individual cells or much like an iceberg . They shed a group , a cluster , which becomes a pellicle , a thin skin or a film , because it floats up to the air surface interface . And by that mechanism it can be transferred to another surface , and it starts the process all over again .”
Alfa continued , “ Dry surface biofilms have always been present in the healthcare environment , but we are becoming more aware of the role they play . For example , you clean and disinfect patient rooms on a regular basis , and you expect you ’ ve done a good job in eliminating the organisms , but you need to appreciate that when dry surface biofilm forms , these organisms can persist for very long periods of time . And even if you try to culture them , they may not show up because they ’ re In the VBNC state .”
The challenge posed by DSBs , she emphasized , is the difficulty with which disinfectants penetrate the biofilm matrix , as well as hand carriage of microorganisms from these biofilms if touched by healthcare personnel . Alfa pointed to research by Chowdhury and Tahir , et al . ( 2019 ) which sought to determine whether DSBs may be transferred from hospital surfaces to healthcare workers ’ hands . In their study , 12-day Staphylococcus aureus DSB was grown on polycarbonate and glass coupons in a CDC Biofilm Reactor , a device designed to study biofilms . A total of 1.8 × 10 6 and 8.8 × 10 5 bacteria grew on the polycarbonate and glass coupons respectively . Transmission was tested by lifting the coupon with forefinger and thumb of ungloved hands to a height of 30 cm , then touching agar plates 19 sequential times . Transferred bacterial number was determined by colony-forming units . The effect of DSB wetting on biofilm transfer was tested with 5 percent neutral detergent treatment for 5 seconds .
The researchers discovered between 5.5 percent and 6.6 percent of the DSB bacteria were transferred to hands with one touch and about 20 percent were then transferred to agar plates with one touch , giving an overall transfer rate of 1.26 percent and 1.04 percent for polycarbonate and glass coupons , respectively . Detergent treatment had little effect on bacterial removal from coupons , but for biofilm grown on polycarbonate , significantly increased transferal to agar plates to 5.2 percent . Large numbers of bacteria were transferred by bare hands to multiple fomites . One-third of polycarbonate coupons transferred more than 1,000 colonies during the first five sequential touches . Sufficient bacteria to cause infection were transmitted up to 19 times following one touch of the DSB . The researchers emphasize that DSB bacteria are transferred by hands from one fomite to multiple fomites , suggesting that DSB may serve as a persistent environmental source of pathogens .
“ This study shows that gloved hands are capable of transferring organisms from DSB as they touch other surfaces ,” Alfa said . “ That is significant because if you are cleaning a patient ’ s room and you ’ re touching the
environment with gloved hands , you think that you ’ re protecting yourself by wearing gloves and protecting the patient by cleaning the room , but the reality is that gloves can also transfer those organisms , especially if they haven ’ t been properly cleaned and disinfected .
The researchers then asked , “ What if we put liquid detergent on the DSB , does that change the kinetics of how much is picked up and how much is transferred ?” Alfa noted , “ Remember , there ’ s no friction in this . In these tests it ’ s either DSB touched or wetted with a detergent , not a disinfectant , and no friction , no rubbing . The results are that out of the six logs , the nitrile gloves now are picking up three logs . The latex gloves are picking up two logs and the surgical gloves are picking up three logs and they transfer it even longer , up to 17 transfers by touching consecutive surfaces 17 times — organisms are still being shed onto those surfaces . So , the issue here is that we need to be aware that if there is the potential for the presence of DSB , if you touch it , you can certainly transfer it as the dry form . And if you are cleaning it with a detergent , you ’ re going to pick up even more on your gloves and transfer it , and so there ’ s significant concern . We think that this is the way that some of the DSB organisms get distributed within the healthcare setting , including transmission of Staph aureus in DSB by gloved-hand contact .”
Alfa pointed to research by Parvin , et al . ( 2019 ) who demonstrated that a Staphylococcus aureus biofilm is significantly more difficult to remove than dried planktonic bacteria . They found that a single wiping action removed more than 99.9 percent (> 3 log10 ) of dried planktonic bacteria , whereas only 1.4 log10 of biofilm ( 96.66 percent ) was removed by 50 wiping actions with a standardized wiping process .
“ In this study , the researchers used Staph aureus in a DSB and asked the question , ‘ What happens if we use commercial products that have 1,000 parts per million of chlorine on planktonic bacteria , traditional biofilm and DSB ,” Alfa said . “ The researchers found that if you expose the biofilm to 5 minutes of contact , which is actually quite a long time of contact when you think about it , as often the fluids dry up before that 5 minutes is over ; but the point being that the planktonic six logs were on the surface of each one of these forms , but 1,000 parts per million exposed for 5 minutes completely eradicated the planktonic bacteria . It also eradicated the immature three-day biofilm . There are no detectable viable organisms , but with the 12-day traditional biofilm , it was able to eliminate only about three and a half logs out of the six logs , and DSB is even more dastardly to try to eradicate the organisms . The take-home message here is that as we go from planktonic to biofilm to dry surface biofilm , it gets harder and harder to kill with disinfectants what traditionally would be able to eradicate planktonic ones with no problem . The researchers tried to determine how much it takes to eradicate a DSB , and they found it was only achievable
16 july 2023 • www . healthcarehygienemagazine . com