By the time the University of Chicago's Center for Care and Discovery opened, researchers had already been swabbing the hospital for two months, with the aim of learning how germs spread through a hospital's environment.
"The Hospital Microbiome Project is the single biggest microbiome analysis of a hospital performed, and one of the largest microbiome studies ever," Jack Gilbert, PhD, told Science Life, a publication of The University of Chicago Medicine & Biological Sciences. Dr. Gilbert led the research and authored a study published Wednesday in Science Translational Medicine.
The study started two months prior to the hospital opening its doors to patients on Feb. 23, 2013, and continued for 10 months after. Researchers swabbed 10 patient care rooms and two nursing stations daily, as well as the patients in those rooms and the nurses caring for them.
They found the following:
1. Human germs take over quickly. Before the hospital opened, bacteria like Acinetobacter and Pseudomonas were common. However, human-related germs like Corynebacterium, Staphylococcus and Streptococcus soon took over after the hospital opened. "As soon as [the hospital] was populated with patients, doctors and nurses, the bacteria from their skin took over," Dr. Gilbert said in Science Life.
2. Patients bring in infection-causing germs. According to coverage in Science, 20 of the 252 patients in the study suffered a hospital-acquired infection during their stay. But when researchers swabbed their rooms and the clinicians who cared for them, they failed to find the germs responsible for the infection. "The most likely explanation is the patients already had those bacteria when they were admitted," Dr. Gilbert told Science.
3. Patients quickly contribute to the room's microbiome. When patients first occupy a room, they tend to pick up germs from the surrounding area. But within the first 24 hours, the transmission route reverses and "the patient's microbiome takes over the hospital space," Dr. Gilbert told Science Life.
4. Surfaces are more likely to harbor drug-resistant germs than patients' skin. "[G]enes conferring antimicrobial resistance were consistently more abundant on room surfaces than on the skin of the patients inhabiting those rooms," the study authors wrote.
5. Staff were more likely to pass germs to patients than vice versa. "[A]nalysis suggested that hospital staff were more likely to be a source of bacteria on the skin of patients than the reverse," the study concludes.
6. Longer hospital stays could promote antibiotic resistance. Per Science Life, "Samples from the rooms of 92 patients who had longer hospital stays, measured in months, revealed a trend. 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."
7. Weather affects germ spread. When the weather is warmer and more humid, staff members passed more bacteria among each other, the researchers found.