Scientists Reveal Where Most ‘Hospital’ Infections Actually Come From : ScienceAlert

Healthcare providers and patients traditionally think that infections patients get in hospitals are caused by superbugs they are exposed to while in a medical facility.

Genetic data of the bacteria responsible for these infections – consider CSI for E.coli – tells another story: Most hospital-acquired infections are caused by previously harmless bacteria that patients already had on their bodies before they even entered the hospital.

Research comparing microbiome bacteria – those that colonize our noses, skin and other parts of the body – with bacteria that cause pneumonia, diarrhea, bloodstream infections and surgical site infections shows that bacteria living harmlessly on our own bodies when we are healthy. are most often responsible for these bad infections when we are sick.

Our research recently published in Science Translational Medicine adds to the growing number of studies supporting this idea. We show that many surgical site infections after spine surgery are caused by microbes already present on the patient’s skin.

Surgical infections are a persistent problem

Among the different types of nosocomial infections, surgical site infections are particularly problematic. A 2013 study found that surgical site infections contribute the most to the annual costs of hospital-acquired infections, totaling more than 33% of the US$9.8 billion spent each year.

Surgical site infections are also a significant cause of hospital readmission and death after surgery.

In our work as clinicians at the University of Washington’s Harborview Medical Center — yes, the one in Seattle that “Grey’s Anatomy” is supposedly based on — we’ve seen how hospitals go to extraordinary lengths to prevent these infections. These include sterilizing all surgical equipment, using ultraviolet light to clean the operating room, following strict protocols for surgical attire, and monitoring airflow in the operating room. operation.

Yet surgical site infections occur after about 1 in 30 procedures, usually without explanation. While rates of many other medical complications have shown steady improvement over time, data from the Agency for Healthcare Research and Quality and the Centers for Disease Control and Prevention show that the problem of Surgical site infection does not improve.

In fact, because the administration of antibiotics during surgery is the cornerstone of infection prevention, the global increase in antibiotic resistance is predicted to lead to increased infection rates after surgery.

BYOB (bring your own bacteria)

As a team of physician scientists with expertise in critical care, infectious disease, laboratory medicine, microbiology, pharmacy, orthopedics and neurosurgery, we wanted to better understand how and why surgical infections occurred in our patients despite following recommended protocols to prevent them.

Previous studies of surgical site infection were limited to a single species of bacteria and used older genetic analysis methods. But new technologies have opened the door to studying all types of bacteria and testing their antibiotic resistance genes simultaneously.

We focused on infections in spine surgery for several reasons. First, similar numbers of women and men undergo spinal surgery for a variety of reasons over the course of their lives, meaning our findings would be applicable to a broader group of people.

Second, in the United States, more health care resources are devoted to spine surgery than any other type of surgical procedure. Third, infections following spinal surgery can be particularly devastating for patients, as they often require repeated surgeries and long courses of antibiotics to have any chance of recovery. .

Over a period of one year, we sampled the bacteria living in the noses, skin and stools of more than 200 patients before surgery. We then followed this group for 90 days to compare these samples with any infections that occurred subsequently.

Staphylococcus aureus is a common cause of nosocomial bacterial infections. (Janice Haney Carr/Jeff Hageman, MHS/CDC)

Our results revealed that although the species of bacteria living on the skin on patients’ backs vary greatly from person to person, there are clear trends. The bacteria colonizing the upper back around the neck and shoulders are more similar to those in the nose; those normally found in the lower back are more similar to those in the intestines and stools. The relative frequency of their presence in these skin regions closely reflects the frequency with which they appear in infections after surgery on these same specific regions of the spine.

In fact, 86 percent of the bacteria causing infections after spinal surgery were genetically associated with the bacteria the patient carried before surgery. This number is remarkably close to estimates from previous studies using older genetic techniques focused on Staphylococcus aureus.

Nearly 60 percent of infections were also resistant to the preventative antibiotic given during surgery, the antiseptic used to clean the skin before the incision, or both.

It turns out that the source of this antibiotic resistance was also not acquired in the hospital but from microbes with which the patient was already living without knowing it. They likely acquired these antibiotic-resistant microbes through previous exposure to antibiotics, consumer products, or regular community contact.

Prevent surgical infections

At first glance, our results may seem intuitive: surgical wound infections come from bacteria hanging around that part of the body. But this awareness has potentially important implications for prevention and care.

If the most likely source of surgical infection – the patient’s microbiome – is known in advance, medical teams have the opportunity to protect against it before a scheduled procedure. Current infection prevention protocols, such as antibiotics or topical antiseptics, follow a single model – for example, the antibiotic cefazolin is used for any patient undergoing most procedures – but personalization could make them more effective.

If you were to have major surgery today, no one would know if the site where your incision will be made is colonized with bacteria resistant to the standard antibiotic regimen for that procedure. In the future, clinicians may use information about your microbiome to select more targeted antimicrobials. But more research is needed to know how to interpret this information and understand whether such an approach would ultimately lead to better results.

Today, practice guidelines, commercial product development, hospital protocols, and accreditation related to infection prevention often focus on the sterility of the physical environment. The fact that most infections do not actually start from hospital sources is likely a testament to the effectiveness of these protocols.

But we believe that moving toward more patient-centered and individualized infection prevention approaches could potentially benefit hospitals and patients.The conversation

Dustin Long, Assistant Professor of Anesthesiology, School of Medicine, University of Washington and Chloe Bryson-Cahn, Associate Professor of Allergy and Infectious Diseases, School of Medicine, University of Washington

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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