Tracing The Microbial Footprint

There are few opportunities to really track the movement of organisms in a healthcare setting without the ever present microbial “background noise”. Lucky for us, researchers in Chicago had this rare and exciting opportunity.

Prior to the opening of the University of Chicago Medicine’s Center for Care and Discovery, researchers, led by Simon Lax, PhD, and Jack Gilbert, PhD, collected bacterial samples to truly paint the full picture of microbial movement within healthcare. For their baseline information, the team collected samples from surfaces in 10 patient rooms and nursing stations that were considered the most “high-touch”, such as bed rails, computer mice, counter tops, etc. Not surprisingly, the researchers found that the microbial diversity among samples increased when the hospital opened. They collected samples every day for ten months, which resulted in over 10,000 samples.

Interestingly, the most prevalent microbes the researchers found prior to the hospital opening were Pseudomonas and Acinetobacter; however, this changed following the start of patient care when Corynebacterium, Staphylococcus, and Streptococcus became dominate.

This study is not only one of the biggest of its kind, but it also showed the movement of bacteria and how challenging environmental disinfection can be. Healthcare disinfection, particularly in patient rooms and nursing stations, is increasingly being scrutinized. One of the many interesting findings was that when a new patient was admitted to the hospital, they tended to pick up whatever microbes were there from the patient who previously occupied that room; however, within 24 hours, the roles reversed. After a patient was in the room for a day, the composition of the room’s microbes began to change and mirror that of the new patient. The “bacterial communities” within the patient’s room become a reflection of those germs that the patient was actually carrying. This is not totally unusual as most researchers and infection preventionists will tell you that even if a patient is unconscious or immobile, those germs find their way around the room through healthcare workers, ancillary staff, and even visitors.

Because of these challenges and the increasing scrutiny on healthcare-associated infections, even disinfecting manufacturers are having to ramp up their tactics. Whether it is through UV disinfection systems, wipes that can kill just about anything, or sheets with copper embedded in them, disinfection products and practices are having to evolve to truly fight the battle of the bug. Moreover, the researchers in the study found that bacteria with antimicrobial resistance genes were more abundant on surfaces in the room than on the skin of the patient within the room, meaning that healthcare workers do not even have to come in direct contact with the patient to spread the bugs. Although this makes its seem like every patient room is covered in a Jackson Pollock of germs, most of them are pretty low impact and tend to be common commensals, or common skin germs.

Researchers also stumbled upon the finding that a majority of the admitted patients sampled received antibiotics during admission, which surprisingly, had no impact on the skin microbiome (the ecological community of organisms within our bodies). Despite this high rate of antibiotic prevalence, they found that samples from rooms where patients had longer hospital stays (ie, months), showed an evolutionary shift to resistance.

“Some potentially harmful bacteria, such as Staphylococcus aureus and Staphylococcus epidermidis, faced with continual selective pressure, managed to acquire genes that could boost antibiotic resistance and promote host infection,” according to the University’s press release on the study. This finding gives insight into the microbial shift towards resistance as medical care becomes prolonged and healthcare worker exposures increase, etc.

Overall, this new study highlights the movement of microbes within healthcare and how we can start improving our tactics to help reduce the risk of healthcare-associated infections and blossoming bacterial resistance.