By analyzing strains of the bacterium from a hospital ICU, the scientists learned that most infections were triggered within patients, not from cross-transmission
Tracking the source of Hospital-acquired infections (HAI) has long been centered around the assumption that most HAIs originate from cross-transmission within the hospital or healthcare setting. And prevention measures are costly for hospitals and medical laboratories. However, new research puts a surprising new angle on a different source for some proportion of these infections.
The study suggests that most infections caused by Clostridioides difficile (C. Diff), the bacterium most responsible for HAIs, arise not from cross-transmission in the hospital, but within patients who already carry the bacterium.
A researcher performed whole genome sequencing on 425 strains of the bacterium isolated from the samples and found “very little evidence that the strains of C. diff from one patient to the next were the same, which would imply in-hospital acquisition,” according to a UM news story.
“In fact, there were only six genomically supported transmissions over the study period. Instead, people who were already colonized were at greater risk of transitioning to infection,” UM stated.
Arianna Miles-Jay, PhD, a postdoctoral fellow in The Snitkin Lab at the University of Michigan and Manager of the Genomic Analysis Unit at the Michigan Department of Health and Human Services, performed the genomic sequencing. “By systematically culturing every patient, we thought we could understand how transmission was happening. The surprise was that, based on the genomics, there was very little transmission,” she said in the UM news story.
“Something happened to these patients that we still don’t understand to trigger the transition from C. diff hanging out in the gut to the organism causing diarrhea and the other complications resulting from infection,” said Evan Snitkin, PhD (above), Associate Professor of Microbiology and Immunology, and Associate Professor of Internal Medicine, Division of Infectious Diseases at University of Michigan, in a UM news story. Medical laboratories involved in hospital-acquired infection prevention understand the importance of this research and its effect on patient safety. (Photo copyright: University of Michigan.)
Only a Fraction of HAIs Are Through Cross-Transmission
In the study abstract, the researchers wrote that “despite enhanced infection prevention efforts, Clostridioides difficile remains the leading cause of healthcare-associated infections in the United States.”
Citing data from the US Centers for Disease Control and Prevention (CDC), HealthDay reported that “nearly half a million C. diff infections occur in the United States each year. Between 13,000 and 16,000 people die from the bacterium, which causes watery diarrhea and inflammation of the colon. Many of these infections and deaths have been blamed on transmission between hospitalized patients.”
The new study, however, notes that 9.3% of the patients admitted to the ICU carried toxigenic (produces toxins) C. diff, but only 1% acquired it via cross-transmission. The carriers, the study authors wrote, “posed minimal risk to others,” but were 24 times more likely to develop a C. diff infection than non-carriers.
“Our findings suggest that measures in place in the ICU at the time of the study—high rates of compliance with hand hygiene among healthcare personnel, routine environmental disinfection with an agent active against C. diff, and single patient rooms —were effective in preventing C. diff transmission,” Snitkin told HealthDay. “This indicates that to make further progress in protecting patients from developing C. diff infections will require improving our understanding of the triggers that lead patients asymptomatically carrying C. diff to transition to having infections.”
Recognizing Risk Factors
Despite the finding that infections were largely triggered within the patients, the researchers still emphasized the importance of taking measures to prevent hospital-acquired infections.
“In fact, the measures in place in the Rush ICU at the time of the study—high rates of compliance with hand hygiene among healthcare personnel, routine environmental disinfection with an agent active against C. diff, and single patient rooms—were likely responsible for the low transmission rate,” the UM news story noted.
One expert not involved with the study suggested that hospitals’ use of antibiotics may be a factor in causing C. diff carriers to develop infections.
“These findings suggest that while we should continue our current infection prevention strategies, attention should also be given to identifying the individuals who are asymptomatic carriers and finding ways to reduce their risk of developing an infection, like carefully optimizing antibiotic usage and recognizing other risk factors,” Hannah Newman, Senior Director of Infection Prevention at Lenox Hill Hospital in New York City, told HealthDay.
Snitkin, however, told HealthDay that other factors are likely at play. “There is support for antibiotic disruption of the microbiota being one type of trigger event, but there is certainly more to it than that, as not every patient who carries C. diff and receives antibiotics will develop an infection.”
Another expert not involved with the study told HealthDay that “many patients are already colonized,” especially older ones or those who have been previously hospitalized.
“A lot of their normal flora in their GI tract can be altered either through surgery or antibiotics or some other mechanism, and then symptoms occur, and that’s when they are treated with antibiotics,” said Donna Armellino, RN, Senior VP of Infection Prevention at Northwell Health in Manhasset, New York.
This research also demonstrates the value of faster, cheaper, more accurate gene sequencing for researching life-threatening conditions. Microbiologists, Clinical laboratory scientists, and pathologists will want monitor further developments involving these findings as researchers from University of Michigan and Rush University Medical Center continue to learn more about the source of C. diff infections.
be interested to learn of new research designed to better identify sources of hospital-acquired
infections, including investigating possibilities that have not been previously
Thus, the results of this research could impact not only the
hygiene and disinfectant procedures of healthcare workers, but the designs of
future MICU rooms and possibly even change the plumbing requirements throughout
entire healthcare facilities. These new findings may also create new factors
for hospital infection control teams and microbiologists to consider when
investigating the sources of nosocomial infections.
The MCW researchers conducted their investigation in a
600-bed Wisconsin hospital with a 26-bed MICU “in which each room has:
“a patient bed;
“two sinks; and,
“a toilet without physical barriers in between.
“Each room is surface-cleaned (including sink bowls, but not drains) with hydrogen peroxide/peracetic acid on a daily basis. Separate cloths are used to clean each of the two sinks in patient rooms to avoid cross-contamination,” the study notes.
The MCW researchers found:
“KPC–producing organisms persist in sink drains
in intensive care units without recent history of carbapenem-resistant
“A high prevalence of [beta-lactamase Klebsiella pneumoniae carbapenemase]
(blaKPC) polymerase chain reaction-positive (54%) and culture-positive (9%)
sink drains; and,
“Sinks near toilets were four times more likely
to be positive (87%) than sinks distal to toilets (22%).”
However, the MICU did not have any documented interactions
with KPC-producing organisms within the past year, the press release noted.
Other Studies into KPCs,
HAIs, and Human Gut Microbiota
New technologies that allow researchers to follow novel,
unexplored paths to learn about potential sources of infections might
contribute to fewer hospital-acquired infections and improved outcomes for both
patients and those who work in healthcare settings.
Medical laboratories play a critical important role in this
by identifying and typing bacteria in hospital settings, especially those that
are resistant to current antibiotics. New approaches to locating such bacteria
continue to be investigated and the tools available to learn more about them
are becoming more powerful and widely available.
Regardless of the origin, protecting staff and patients from
HAIs is critical. Clinical laboratory involvement in protecting patients, and monitoring,
investigating, and managing outbreaks, are key to controlling the spread of
these dangerous bacteria.
Brazilian study finds Staph, E. coli, and other bacteria that contribute to hospital-acquired infections in reusable water bottles used by members of multiple fitness centers
In the latest example of Microbiologists swabbing
and culturing samples taken from common, everyday items, a research team in
Brazil has found germs associated with hospital-acquired
infections (HAIs) infections on reusable water bottles carried by
individuals working out in local fitness clubs.
Their results may cause gym members to consider the impact
the bottles they tote can have on their health.
Worse than Licking a
The researchers analyzed the presence of different bacterial
strains in the water bottles of 30 fitness club members at two different
fitness center locations, as well as 30 new unused bottles. They also conducted
susceptibility tests for the isolated strains.
The scientists found contamination in 90% of the used
plastic bottles, while none of the new bottles showed signs of bacterial
contamination. Twenty-five (83%) of the used bottles contained Staph (26.66%)
and E. coli (16.66%). In addition, four of the reused bottles tested positive
for the presence Pseudomonas,
an antibiotic-resistant bacterium that also causes HAIs.
Similar results were found in testing performed by the website
TreadmillReviews.net. That study
revealed an average athlete’s water bottle contained 313,499 viable bacteria
cells (313,400 colony-forming units per square centimeter).
“To put it bluntly, drinking from the average refillable
bottle can be many times worse than licking your dog’s toy,” Treadmill Reviews noted.
Presence of Staph and E. coli
Despite the ick-factor of the water-bottle testing results, Runner’s World also notes that the Centers for Disease Control and Prevention (CDC)
determined that Staph bacteria can be found in the noses of 30% of the
population, while E. coli is present in healthy gastro intestinal tracts, with
only certain strains causing illness.
The Brazilian study’s authors also noted that most of the
bacteria isolated in their research belong to the Enterobacteria group,
which lives in the intestines and are pathogenic. Thus, the
researchers surmised that “manipulation with contaminated hands may contribute
to the colonization of the [reusable water bottles].
“We conclude the best way to avoid bacterial proliferation
in the [reusable water bottles] is to make sure they are correctly and
frequently cleaned, such as daily washing with neutral soup in association with
proper hand hygiene to prevent contamination,” Senna and co-authors wrote.
Tierno, Jr, PhD, Professor of Microbiology and Pathology at New York University (NYU) and the NYU Langone Medical Center supports the study’s conclusions.
He suggests water bottles likely become contaminated through handling by their
owners, an issue proper hand hygiene can help remedy. He recommends properly
washing hands before filling a gym water bottle.
“Wash 20 seconds,” Tierno told Runner’s World. “Get soap on the top and bottom of hands and in
between digits and under the nail bed. Run your hands like a claw in the center
of the opposite palm to get suds into the nail bed, and sing the song ‘Happy
Birthday’ twice to wash hands adequately.”
Reusable water bottles also should be cleaned thoroughly,
preferably in a dishwasher.
Until the general public begins routinely following such
advice, microbiologists and clinical
pathologists will remain the tip of the spear in infection control programs
and education. But that should not stop clinical laboratory managers from
implementing constant monitoring and cleaning protocols to stop the spread of
infectious bacteria in their labs.
Even more compelling was the discovery of DNA from the Staph bacteria on the stethoscopes even after they were cleaned. Though the tests could not differentiate between live and dead bacteria, the researchers found other non-Staph bacteria as well, including Pseudomonas and Acinetobacter.
Similar conditions could no doubt be found in most
healthcare settings in America, highlighting the critical importance for
rigorous cleaning procedures and protocols.
The researchers acknowledged that previous culture-based bacterial
studies looked at stethoscopes, but noted the results fell short of the view
next-generation sequencing technology can offer for identifying bacteria, as
well as determining the effectiveness of cleaning chemicals and regiments.
“Culture-based studies, which focus on individual organisms,
have implicated stethoscopes as potential vectors of nosocomial bacterial
transmission [HAI]. However, the full bacterial communities that contaminate
in-use stethoscopes have not been investigated,” they wrote in Infection Control and Hospital Epidemiology.
• 20 worn by physicians, nurses, and respiratory therapists;
• 20 single patient-use disposable stethoscopes available in ICU patient rooms; and,
• 10 unused single-use disposable stethoscopes to serve as a control.
All stethoscopes worn and/or used in the ICU were found to be contaminated with abundant amounts of Staphylococcus DNA. “Definitive” amounts of Staph was found by researchers on 24 of 40 tested devices, noted MedPage Today.
“Genera relevant to healthcare-associated infections (HAIs)
were common on practitioner stethoscopes, among which Staphylococcus was ubiquitous
and had the highest relative abundance (6.8% to 14% of containment bacterial
sequences),” the researchers noted in their paper.
Cleaning Methods Also
The researchers also studied the hospital’s cleaning agents
• 10 practitioner stethoscopes were examined before and after a standard 60-second cleaning procedure using hydrogen peroxide wipes;
• 20 additional stethoscopes were assessed before and after cleaning by practitioners using alcohol wipes, hydrogen peroxide wipes, or bleach wipes.
All methods reduced bacteria. But not to the levels of a new
stethoscope, the study showed.
“Stethoscopes used in an ICU carry bacterial DNA reflecting complex microbial communities that include nosocomially important taxa. Commonly used cleaning practices reduce contamination but are only partially successful at modifying or eliminating these communities,” the researchers concluded in their paper.
Prior Studies to Find
and Track Dangerous Bacteria
Studies tracking bacteria where people live, work, and
travel are not new. For years, medical technologists and microbiologists have
roamed the halls of hospitals and other clinical settings to swab and culture
different surfaces and even articles of clothing. These efforts are often
associated with programs to reduce nosocomial infections (HAIs).
This new study by UPenn Perelman School of Medicine researchers—published
in a peer-reviewed medical journal—will hopefully serve as a contemporary
reminder to doctors and other caregivers of how bacteria can be transmitted and
the critical importance of cleanliness, not only of hands, but also
stethoscopes (and neckties).
Hospital-based medical laboratory leaders and microbiology professionals also can help by joining with their infection control colleagues to advocate for CDC-recommended disinfection and sterilization guidelines throughout their healthcare networks.
New bioinformatic tool finds gut microbiota may be ‘potential reservoir of bloodstream pathogens’ suggesting patients’ own bodies can be source of infections
Clinical laboratories in hospitals and health networks throughout the nation are collaborating in the priority effort to reduce deaths from sepsis and related blood infections. Now comes news that researchers at Stanford have identified an unexpected source of bloodstream infections. This finding may help medical laboratories contribute to faster and more accurate diagnoses of blood infections, particularly for hospital inpatients.
Lax infection-control practices often are blamed for hospital-acquired infections (HAIs). And HAIs certainly have been responsible for many tragic avoidable deaths. However, new research from Stanford University School of Medicine shows that hospital staff, other patients, or unclean instruments may not be solely responsible for all infections that present during hospital stays. According to Stanford researchers, a patient’s own digestive tract can be the surprising culprit for many bloodstream infections. This finding confirms a common belief that the patient’s microbiome probably is involved in many blood infections.
Bacteria Causing Blood Infections Found in Patients’ Stool Samples After Bone Marrow Transplants
Using a new bioinformatic computational tool called StrainSifter, the Stanford University team rapidly and accurately identified a surprising infection source in a group of hospitalized patients—microbes already living in the patients’ large intestines—a Stanford University news release explained.
The researchers analyzed blood and stool samples from 30 patients who developed bloodstream infections after receiving bone marrow transplants between October 2015 and June 2017 at Stanford Hospital. The researchers sought to determine whether the bacteria isolated from the patients’ blood also was found in stool specimens that had been collected prior to the transplants. The process required sequencing not only the patients’ DNA, but also analyzing the genomes of all the individual microbial strains resident in each patient’s stool.
“Just finding E. coli in a patient’s blood and again in the patient’s stool doesn’t mean they’re the same strain,” Ami Bhatt, MD, PhD, Assistant Professor of Hematology and Genetics at Stanford, explained in the news release. Bhatt served as senior author of the study. (Photo copyright: Stanford University.)
Analysis found that more than one-third of the patients’ stool samples (11) contained detectable levels of the same bacterial strain that had caused those patients’ bloodstream infections.
“Because the gut normally harbors more than 1,000 different bacterial strains, it’s looked upon as a likely culprit of bloodstream infections, especially when the identified pathogen is one known to thrive inside the gut,” Ami Bhatt, MD, PhD, Assistant Professor of Hematology and Genetics at Stanford, said in the news release. “But while this culpability has been assumed—and it’s an entirely reasonable assumption—it’s never been proven. Our study demonstrates that it’s true.”
Clinical and DNA data confirmed the gastrointestinal presence of Escherichia coli and Klebsiella pneumonia, common causes of pneumonia, urinary tract infections, and other potentially serious conditions. In addition, they found other disease-causing pathogens in the gut that they would not have expected to be there.
“We also find cases where typically nonenteric [outside the intestine] pathogens, such as Pseudomonas aeruginosa and Staphylococcus epidermidis, are found in the gut microbiota, thereby challenging the existing informal dogma of these infections originating from environmental or skin sources,” Fiona Tamburini, a senior graduate student, and postdoctoral scholar Tessa Andermann, MD, MPH, Infectious Disease Medical Fellow, wrote in Nature Medicine.
New Tool for Precision Medicine
Bhatt believes being able to trace the source of bloodstream infections will help doctors provide more targeted treatments for HAIs and potentially lead to effective prevention methods. This will create a new opportunity for microbiology laboratories to provide the necessary diagnostic tests designed to guide therapeutic choices of attending physicians.
“Until now, we couldn’t pinpoint those sources with high confidence,” Bhatt said in the news release. “That’s a problem because when a patient has a bloodstream infection, it’s not enough simply to administer broad-spectrum antibiotics. You need to treat the source, or the infection will come back.”
Bhatt says the computational tool has the potential to allow medical practitioners to quickly identify whether a pathogen responsible for a patient’s bloodstream infection came from a break in the skin, leaked through the intestinal wall into the blood, or was passed on through an inserted catheter or other object.
Bhatt’s team focused on the intestines for their study because it’s the home of 1,000 to 2,000 different germs. Dark Daily has reported often on developments involving human gut bacteria (AKA, microbiome) in e-briefings going back to 2013. While these gut bacteria do not typically cause problems, Bhatt said, “It’s only when they show up in the wrong place—due, for example, to leaking through a disrupted intestinal barrier into the bloodstream—that they cause trouble.”
Because nearly 40% of immunocompromised patients who spend up to six weeks in a hospital develop bloodstream infections, the Stanford findings could signal a major breakthrough in preventing HAIs. However, larger studies are needed to validate the researchers’ contention that the gut is a “potential reservoir of bloodstreams pathogens.”
If true, microbiologists and clinical pathologists may in the future have a new method for helping hospitals identify, track, and treat blood-born infections as well as and preventing HAIs.