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Woman Performs Do-it-yourself Fecal Transplant to Relieve Symptoms of IBS, Gets Donor’s Acne

Clinical laboratory scientists and microbiologists could play a role in helping doctors explain to patients the potential dangers of do-it-yourself medical treatments

Be careful what you wish for when you perform do-it-yourself (DIY) medical treatments. That’s the lesson learned by a woman who was seeking relief for irritable bowel syndrome (IBS). When college student Daniell Koepke did her own fecal transplant using poop from her brother and her boyfriend as donors her IBS symptoms improved, but she began to experience medical conditions that afflicted both fecal donors.

“It’s possible that the bacteria in the stool can influence inflammation in the recipient’s body, by affecting their metabolism and activating their immune response,” microbial ecologist Jack Gilbert, PhD, Professor and Associate Vice Chancellor at University of California San Diego (UC San Diego) told Business Insider. “This would cause shifts in their hormonal activity, which could promote the bacteria that can cause acne on the skin. We nearly all have this bacterium on skin, but it is often dormant,” he added.

A Fecal Microbiota Transplant (FMT) is a procedure where stool from a healthy donor is transplanted into the microbiome of a patient plagued by a certain medical condition.

Our guts are home to trillions of microorganisms (aka, microbes), known as the gut microbiota, that serve many important functions in the body. The microbiome is a delicate ecosystem which can be pushed out of balance when advantageous microbes are outnumbered by unfavorable ones. An FMT is an uncomplicated and powerful method of repopulating the microbiome with beneficial microbes.   

“With fecal microbiome transplants there is really compelling evidence, but the science is still developing. We’re still working on if it actually has benefits for wider populations and if the benefit is long-lasting,” said Gilbert in a Netflix documentary titled, “Hack Your Health: The Secrets of Your Gut.”

“The microbial community inside our gut can have surprising influences on different parts of our body,” microbial ecologist Jack Gilbert, PhD (above), of the Gilbert Lab at University of California San Diego told Business Insider. “Stools are screened before clinical FMTs, and anything that could cause major problems, such as certain pathogens, would be detected. When you do this at home, you don’t get that kind of screening.” Doctors and clinical laboratories screening patients for IBS understand the dangers of DIY medical treatments. (Photo copyright: University of California San Diego.)

Changing Poop Donors

When Koepke began experiencing symptoms of IBS including indigestion, stabbing pains from trapped gas and severe constipation, she initially turned to physicians for help.

In the Netflix documentary, Koepke stated that she was being prescribed antibiotics “like candy.” Over the course of five years, she completed six rounds of antibiotics per year, but to no avail.

She also changed her diet, removing foods that were making her symptoms worse. This caused her to lose weight and she eventually reached a point where she could only eat 10 to 15 foods. 

“It’s really hard for me to remember what it was like to eat food before it became associated with anxiety and pain and discomfort,” she said.

In an attempt to relieve her IBS symptoms, Koepke made her own homemade fecal transplant pills using donated stool from her brother. After taking them her IBS symptoms subsided and she slowly gained weight. But she developed hormonal acne just like her brother. 

Koepke then changed donors, using her boyfriend’s poop to make new fecal transplant pills. After she took the new pills, her acne dissipated but she developed depression, just like her boyfriend. 

“Over time, I realized my depression was worse than it’s ever been in my life,” Koepke stated in the documentary.

She believes the microbes that were contributing to her boyfriend’s depression were also transplanted into her via the fecal transplant pills. When she reverted to using her brother’s poop, her depression abated within a week.

Gilbert told Business Insider his research illustrates that people who suffer from depression are lacking certain bacteria in their gut microbiome.

“She may have had the ‘anti-depressant’ bacteria in her gut, but when she swapped her microbiome with his, her anti-depressant bacteria got wiped out,” he said.

FDA Approves FMT Therapy for Certain Conditions

Typically, the fecal material for an FMT procedure performed by a doctor comes from fecal donors who have been rigorously screened for infections and diseases. The donations are mixed with a sterile saline solution and filtered which produces a liquid solution. That solution is then administered to a recipient or frozen for later use. 

Fecal transplant methods include:

On November 30, 2022, the US Food and Drug Administration (FDA) approved the first FMT therapy, called Rebyota, for the prevention of Clostridioides difficile (C. diff.) in adults whose symptoms do not respond to antibiotic therapies. Rebyota is a single-dose treatment that is administered rectally into the gut microbiome at a doctor’s office. 

Then, in April of 2023, the FDA approved the use of a medicine called Vowst, which is the first oral FMT approved by the FDA.

According to the Cleveland Clinic, scientists are exploring the possibility that fecal transplants may be used as a possible treatment for many health conditions, including:

Doctors and clinical laboratories know that do-it-yourself medicine is typically not a good idea for obvious reasons. Patients seldom appreciate all the implications of the symptoms of an illness, nor do they fully understand the potentially dangerous consequences of self-treatment. Scientists are still researching the benefits of fecal microbiota transplants and hope to discover more uses for this treatment. 

—JP Schlingman

Related Information:

A Woman Gave Herself Poop Transplants Using Her Brother’s Feces to Treat Debilitating IBS. Then She Started Getting Acne Just Like Him.

FDA Approves First Orally Administered Fecal Microbiota Product for the Prevention of Recurrence of Clostridioides Difficile Infection

FDA Approves First FMT Therapy and Issues Guidance

Everything You Want to Know about Irritable Bowel Syndrome (IBS)

Stanford University Scientists Discover New Lifeform Residing in Human Microbiome

Microbiome Firm Raises $86.5 Million and Inks Deal to Sell Consumer Test Kits in 200 CVS Pharmacies

Researchers Find Health of Human Microbiome Greatly Influenced by Foods We Eat

San Diego University Researchers Believe Bacteriophages May Be the Future of Eradicating Multi-Drug Resistant Superbugs

Clinical laboratories and microbiologists may soon have new powerful tools for fighting antimicrobial resistant bacteria that saves lives

Superbugs—microbes that have developed multidrug resistance—continue to cause problems for clinical laboratories and hospital antibiotic stewardship programs around the world. Now, scientists at San Diego State University (SDSU) believe that bacteriophages (phages) could provide a solution for dealing with multi-drug resistant superbugs.

Phages are miniscule, tripod-looking viruses that are genetically programmed to locate, attack, and eradicate a specific kind of pathogen. These microscopic creatures have saved lives and are being touted as a potential solution to superbugs, which are strains of bacteria, viruses, parasites, and fungi that are resistant to most antibiotics and other treatments utilized to counteract infections.

“These multi-drug-resistant superbugs can cause chronic infections in individuals for months to years to sometimes decades,” Dwayne Roach, PhD, Assistant Professor of Bacteriophages, Infectious Disease, and Immunology at SDSU told CNN. “It’s ridiculous just how virulent some of these bacteria get over time.”

Labs across the country are conducting research on phages in eradicating superbugs. Roach’s lab is currently probing the body’s immune response to phages and developing purification techniques to prepare phage samples for intravenous use in patients.

“There are a lot of approaches right now that are happening in parallel,” said Dwayne Roach, PhD (above), Assistant Professor of Bacteriophages, Infectious Disease, and Immunology at San Diego State University (SDSU), in a CNN interview. “Do we engineer phages? Do we make a phage cocktail, and then how big is the cocktail? Is it two phages or 12 phages? Should phages be inhaled, applied topically, or injected intravenously? There’s a lot of work underway on exactly how to best do this.” Clinical laboratories that test for bacterial infections may play a key role in diagnosis and treatment involving bacteriophages. (Photo copyright: San Diego State University.)

Building Libraries of Phages

When certain a bacterial species or its genotypes needs to be annihilated, a collection of phages can be created to attack it via methods that enter and weaken the bacterial cell. The bacteria will attempt to counter the intrusion by employing evasive actions, such as shedding outer skins to eliminate the docking ports utilized by the phages. These maneuvers can cause the bacteria to lose their antibiotic resistance, making them vulnerable to destruction. 

Some research labs are developing libraries of phages, accumulating strains found in nature in prime breeding grounds for bacteria to locate the correct phage for a particular infection. Other labs, however, are speeding up the process by producing phages in the lab.

“Rather than just sourcing new phages from the environment, we have a bioreactor that in real time creates billions upon billions of phages,” Anthony Maresso, PhD, Associate Professor at Baylor College of Medicine in Houston told CNN. “Most of those phages won’t be active against the drug-resistant bacteria, but at some point, there will be a rare variant that has been trained, so to speak, to attack the resistant bacteria, and we’ll add that to our arsenal. It’s a next-generation approach on phage libraries.”

Maresso and his team published their findings in the journal Clinical Infectious Diseases titled, “A Retrospective, Observational Study of 12 Cases of Expanded-Access Customized Phage Therapy: Production, Characteristics, and Clinical Outcomes.”

For the Baylor study, 12 patients were treated with phages customized to each individual’s unique bacterial profile. The antibiotic-resistant bacteria were exterminated in five of the patients, while several others showed improvement.

Clinical trials are currently being executed to test the effectiveness of phages against a variety of chronic health conditions, including:

Using a phage cocktail could be used to treat a superbug outbreak in real time, while preventing a patient from a future infection of the same superbug. 

“The issue is that when patients have infections with these drug-resistant bacteria, they can still carry that organism in or on their bodies even after treatment,” Maroya Walters, PhD, epidemiologist at the federal Centers for Disease Control and Prevention (CDC) told CNN.

“They don’t show any signs or symptoms of illness, but they can get infections again, and they can also transmit the bacteria to other people,” she added.

The colorized transmission electron micrograph above shows numerous phages attached to a bacterial cell wall. Phages are known for their unique structures, which resemble a cross between NASA’s Apollo lunar lander and an arthropod. (Caption and photo copyright: Berkeley Lab.)

More Studies are Needed

According to CDC data, more than 2.8 million antimicrobial-resistant (AMR) infections occur annually in the United States. More than 35,000 people in the country will die as a result of these infections.

In addition, AMR infections are a huge global threat, associated with nearly five million deaths worldwide in 2019. Resistant infections can be extremely difficult and sometimes impossible to treat.

“It’s estimated that by 2050, 10 million people per year—that’s one person every three seconds—is going to be dying from a superbug infection,” epidemiologist Steffanie Strathdee, PhD, Associate Dean of Global Health Services and co-director at the Center for Innovative Phage Applications and Therapeutics (IPATH) at the UC San Diego School of Medicine, told CNN.

The CDC’s 2019 report on bacteria and fungi antimicrobial resistant threats named five pathogens as urgent threats:

More research is needed before phages can be used clinically to treat superbugs. But if phages prove to be useful in fighting antibiotic-resistant bacteria, microbiologists and their clinical laboratories may soon have new tools to help protect patients from these deadly pathogens.

—JP Schlingman

Related Information:

Superbug Crisis Threatens to Kill 10 Million Per Year by 2050. Scientists May Have a Solution

About Antimicrobial Resistance

2019 AR Threats Report

Bacteriophage

Why Antibiotics Fail, and How We Can Do Better

A Retrospective, Observational Study of 12 Cases of Expanded-Access Customized Phage Therapy: Production, Characteristics, and Clinical Outcomes

Cataloging Nature’s Hidden Arsenal: Viruses That Infect Bacteria

UCSB Researchers Discover Superior Culture Medium for Bacterial Testing, along with New Insights into Antimicrobial Resistance

Researchers in US and Israel Detect Fungal DNA in Most Cancer Types Found in the Human Body

Studies could lead to new prognostic biomarkers and clinical laboratory diagnostics for cancer

Might fungi be involved in human cancers? Two separately published studies have found fungal DNA in various cancers in the human body. However, the researchers are unclear on how the fungi got into the cancer cells and if it is affecting the cancers’ pathology. Nevertheless, these discoveries could lead to utilizing tumor-associated fungal DNA as clinical laboratory diagnostics or prognostic biomarkers in the fight against cancer. 

The first study, performed by a team of international researchers from the University of California San Diego (UCSD) and the Weizmann Institute of Science in Israel, detected the presence of fungal DNA or cells in some cancer types.

They published their findings in the peer-reviewed scientific journal Cell, titled, “Pan-cancer Analyses Reveal Cancer-type Specific Fungal Ecologies and Bacteriome Interactions.”  

Ravid Straussman, MD, PhD

“The finding that fungi are commonly present in human tumors should drive us to better explore their potential effects and re-examine almost everything we know about cancer through a ‘microbiome lens,’” said Ravid Straussman, MD, PhD (above), a principal investigator at Weizmann Institute of Science and one of the authors of the study in a UCSD press release. These findings could lead to new clinical laboratory diagnostics and prognostic biomarkers. (Photo copyright: Weizmann Institute of Science.)

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Microbiome Key to Cancer Biology and Detection

To perform their research, the team examined 17,401 samples of patient tissues, blood, and plasma across 35 different types of cancers in four independent cohorts. They discovered fungal DNA and cells in low abundances in many human cancers. 

“The existence of fungi in most human cancers is both a surprise and to be expected,” said biologist Rob Knight, PhD, founding Director of the Center for Microbiome Innovation and Professor of Pediatrics and Computer Science and Engineering at UC San Diego in a UCSD press release. “It is surprising because we don’t know how fungi could get into tumors throughout the body. But it is also expected because it fits the pattern of healthy microbiomes throughout the body, including the gut, mouth and skin, where bacteria and fungi interact as part of a complex community.”

The main highlights of this study include:

  • Fungi detected in the different cancer types were often intracellular.
  • Multiple fungal-bacterial-immune ecologies were detected across tumors.
  • Intratumoral fungi stratified clinical outcomes, including immunotherapy response.
  • Cell-free fungal DNA found in both healthy and cancer patients in early-stage disease.

Fungi found on the human body appear as either environmental fungi, such as yeasts and molds, and commensal fungi, which live either on or inside the body. Both are typically harmless to most healthy people and can provide some benefits, such as improving gut health, but they may also be a contributing factor in some disease.

The researchers found that there were notable parallels between specific fungi and certain factors, such as age, tumor subtypes, smoking status, immunotherapy responses, and survival measures.

“These findings validate the view that the microbiome in its entirety is a key piece of cancer biology and may present significant translational opportunities, not only in cancer detection, but also in other biotech applications related to drug development, cancer evolution, minimal residual disease, relapse, and companion diagnostics,” said Gregory Sepich-Poore, MD, PhD, one of the study’s authors and co-founder and chief analytics officer at biotechnology company Micronoma, in the UCSD press release.  

New Clinical Laboratory Tests to Identify Fungal Species in Cancer

The second study also was published in the journal Cell, titled, “A Pan-cancer Mycobiome Analysis Reveals Fungal Involvement in Gastrointestinal and Lung Tumors.”

Researchers from Duke University and Cornell University uncovered compelling evidence of fungi in multiple cancer types and focused on a detected link between Candida and gastrointestinal cancers.

They found that “several Candida species were enriched in tumor samples and tumor-associated Candida DNA was predictive of decreased survival,” according to their paper.

Their analysis of multiple body sites revealed tumor-associated mycobiomes in fungal cells. The researchers found that fungal spores known as blastomyces were associated with tumor tissues in lung cancers, and that high rates of Candida were present in stomach and colon cancers.

The Duke/Cornell researchers hope their work can provide a framework to develop new tests that can distinguish fungal species in tumors and predict cancer progression and help medical professionals and patients chose the best treatment therapies. 

“These findings open up a lot of exciting research directions, from the development of diagnostics and treatments to studies of the detailed biological mechanisms of fungal relationships to cancers,” said Iliyan Iliev, PhD, Associate Professor of Microbiology and Immunology in Medicine, Weill Cornell Medicine, and one of the authors of the study, in a Weill news release.

More research is needed to determine if fungal DNA plays a role in disease pathology or if its presence does not have any causal link.

“It’s plausible that some of these fungi are promoting tumor progression and metastasis, but even if they aren’t, they could be very valuable as prognostic indicators,” Iliev said.

The insights gleaned from these two studies will be of particular interest to microbiologists, clinical laboratory professionals, and anatomic pathologists. Additional research could answer questions about how and if fungi infect tumors and if such fungi is a factor that increases cancer risk and outcomes. 

JP Schlingman

Related Information:

Fungal DNA, Cells Found in Human Tumors

First-ever Mycobiome Atlas Describes Associations Between Cancers and Fungi

Pan-cancer Analyses Reveal Cancer-type Specific Fungal Ecologies and Bacteriome Interactions

A Pan-cancer Mycobiome Analysis Reveals Fungal Involvement in Gastrointestinal and Lung Tumors

Fungal Association with Tumors May Predict Worse Outcomes

Researchers Use Genetic Sequencing and Wastewater Analysis to Detect SARS-CoV-2 Variants and Monkeypox within Communities

Researchers surprised that process designed to detect SARS-CoV-2 also identifies monkeypox in wastewater

Early information about an outbreak in a geographical region can inform local clinical laboratories as to which infectious agents and variants they are likely to see when testing patients who have symptoms. To that end, wastewater testing has become a rich source of early clues as to where COVID-19 outbreaks are spreading and how new variants of the coronavirus are emerging.

Now, scientists in San Diego County are adding monkeypox to its wastewater surveillance, according to an August University of California San Diego (UCSD) Health press release. The team at UCSD uses the same process for detecting SARS-CoV-2.

Ongoing advances in genetic sequencing and digital technologies are making it feasible to test wastewater for infectious agents in ways that were once too time-consuming, too expensive, or simply impossible.

Rob Knight, PhD

“Before wastewater sequencing, the only way to do this was through clinical testing, which is not feasible at large scale, especially in areas with limited resources, public participation, or the capacity to do sufficient testing and sequencing,” said Knight in a UCSD press release. “We’ve shown that wastewater sequencing can successfully track regional infection dynamics with fewer limitations and biases than clinical testing to the benefit of almost any community.” (Photo copyright: UC San Diego News.)

Same Process, Different Virus

Following August’s declaration of a state of emergency by California, San Diego County, and the federal government, UCSD researchers added monkeypox surveillance to UCSD’s existing wastewater surveillance program.

“It’s the same process as SARS-CoV-2 qPCR monitoring, except that we have been testing for a different virus. Monkeypox is a DNA virus, so it is a bit of a surprise that our process optimized for SARS-CoV-2, which is an RNA virus, works so well,” said Rob Knight, PhD, Professor of Pediatrics and Computer Science and Engineering at UCSD and one of the lead authors of the study in the press release.

Knight is also the founding director of the Center for Microbiome Innovation at UCSD.

According to the press release, RNA sequencing from wastewater has two specific benefits:

  • It avoids the potential of clinical testing biases, and
  • It can track changes in the prevalence of SARS-CoV-2 variants over time.

In 2020, at the height of the COVID-19 pandemic, scientists from the University of California San Diego and Scripps Research looked into genetic sequencing of wastewater. They wanted to see if it would provide insights into levels and variants of the SARS-CoV-2 within a specific community.

Individuals who have COVID-19 shed the virus in their stool.

The UCSD/Scripps researchers deployed commercial auto-sampling robots to collect wastewater samples at the main UCSD campus. They analyzed the samples for levels of SARS-CoV-2 RNA at the Expedited COVID-19 Identification Environment (EXCITE) lab at UCSD. After the success of the program on the campus, they extended their research to include other facilities and communities in the San Diego area.

“The coronavirus will continue to spread and evolve, which makes it imperative for public health that we detect new variants early enough to mitigate consequences,” said Knight in a July press release announcing the publication of their study in the journal Nature, titled, “Wastewater Sequencing Reveals Early Cryptic SARS-CoV-2 Variant Transmission.”

Detecting Pathogens Weeks Earlier than Traditional Clinical Laboratory Testing

In July, the scientists successfully determined the genetic mixture of SARS-CoV-2 variants present in wastewater samples by examining just two teaspoons of raw sewage. They found they could accurately identify new variants 14 days before traditional clinical laboratory testing. They detected the presence of the Omicron variant 11 days before it was first reported clinically in the community.

During the study, the team collected and analyzed 21,383 sewage samples, with most of those samples (19,944) being taken from the UCSD campus. They performed genomic sequencing on 600 of the samples and compared them to genomes obtained from clinical swabs. They also compared 31,149 genomes from clinical genomic surveillance to 837 wastewater samples taken from the community.

The scientists distinguished specific viral lineages present in the samples by sequencing the viruses’ complete set of genetic instructions. Mutational differences between the various SARS-CoV-2 variants can be minute and subtle, but also have notable biological deviations.

“Nothing like this had been done before. Sampling and detection efforts began modestly but grew steadily with increased research capacity and experience. Currently, we’re monitoring almost 350 buildings on campus,” said UCSD’s Chancellor Pradeep Khosla, PhD, in the July press release.

“The wastewater program was an essential element of UC San Diego Health’s response to the COVID pandemic,” said Robert Schooley, MD, Infectious Disease Specialist at UC San Diego Health, in the press release. Schooley is also a professor at UCSD School of Medicine, and one of the authors of the study.

“It provided us with real-time intelligence about locations on campus where virus activity was ongoing,” he added. “Wastewater sampling essentially allowed us to ‘swab the noses’ of every person upstream from the collector every day and to use that information to concentrate viral detection efforts at the individual level.”

Monkeypox Added to UCSD Wastewater Surveillance

In August, UCSD officially added the surveillance of the monkeypox virus to their ongoing wastewater surveillance program. A month earlier, the researchers had discerned 10,565.54 viral copies per liter of wastewater. They observed the levels fluctuating and increasing.

On August 2, the scientists detected 189,309.81 viral copies per liter of wastewater. However, it is not yet clear if the monitoring of monkeypox viral loads in wastewater will enable the researchers to accurately predict future infections or case rates.

“We don’t yet know if the data will anticipate case surges like with COVID,” Knight said in the August UCSD press release announcing the addition of monkeypox to the surveillance program. “It depends on when the virus is shed from the body relative to how bad the symptoms are that cause people to seek care. This is, in principle, different for each virus, although in practice wastewater seems to be predictive for multiple viruses.”

Utilization of genetic sequencing of wastewater sampling will continue to develop and improve. “It’s fairly easy to add new pathogens to the process,” said Smruthi Karthikeyan, PhD, an environmental engineer and postdoctoral researcher in Knight’s lab who has overseen wastewater monitoring at UC San Diego. “It’s doable on short notice. We can get more information in the same turnaround time.”

Thus, clinical laboratories engaged in testing programs for COVID-19 may soon see the addition of monkeypox to those processes.

-JP Schlingman

UC San Diego Researchers Add Monkeypox to Wastewater Surveillance

Wastewater Sequencing Reveals Early Cryptic SARS-CoV-2 Variant Transmission

Awash in Potential: Wastewater Provides Early Detection of SARS-CoV-2 Virus

National Wastewater Surveillance System (NWSS)

CDC National Wastewater Surveillance System Locates and Tracks SARS-CoV-2 Coronavirus in the Public’s Wastewater

CDC, HHS Create National Wastewater Surveillance System to Help Monitor and Track Spread of COVID-19

UCSD Scientists Discover a Person’s Skin Microbiome May Make Some Individuals More Attractive to Biting Insects than Others

Research could lead to clinical laboratory tests in service of precision medicine therapies to reduce a person’s susceptibility to being targeted by blood-sucking insects

Ever wonder why some people attract mosquitoes while others do not? Could biting insects pick their victims by smell? Scientists in California believe the answers to these questions could lead to new precision medicine therapies and clinical laboratory tests.

The research revealed evidence that some blood-sucking insects may identify their prey by homing in on the “scent” of chemicals produced by bacteria located in the skin microbiome of animals and humans.  

This is yet another example of research into one area of the human microbiome that might someday lead to a new clinical laboratory test, in this case to determine if a person is more likely to attracts biting insects. If there were such a test, precision medicine therapies could be developed that change an individual’s microbiome to discourage insects from biting that individual.

Then, the clinical laboratory test would have value because it helped diagnose a health condition that is treatable.

Researchers from the University of California San Diego (UCSD) School of Medicine, Department of Pediatrics, and Scripps Institution of Oceanography examined blood-sucking flies that are attracted to bats to learn how the insects choose which bats to feed on. One of the authors of the study, Holly Lutz, PhD, had previously encountered multitudes of bats while performing malaria research in bat caves in Kenya and Uganda.

Lutz is an Assistant Project Scientist, Department of Pediatrics, in the Center for Microbiome Innovation at the UCSD School of Medicine. She is also a Scientific Affiliate at the Field Museum of Natural History.

The researchers published their findings in the scientific journal Molecular Ecology, titled, “Associations Between Afrotropical Bats, Eukaryotic Parasites, and Microbial Symbionts.”

Holly Lutz, PhD

Curiosity regarding why mosquitoes seem to gravitate towards some humans over others was the original catalyst for the UCSD Medical School research. “You know when you go to a barbeque and your friend is getting bombarded by mosquitos, but you’re fine? There is some research to support the idea that the difference in mosquito attraction is linked to your skin microbiome—the unique community of bacteria living on your skin,” said Holly Lutz, PhD (above), first author of the UCSD study. “Keeping in mind that some people are more attractive to mosquitoes than others, I wondered what makes insects attracted to some bats but not others.” Lutz’s research could lead to clinical laboratory tests that drive precision medicine therapies to alter human skin microbiomes and make people less attractive to biting insects. (Photo copyright: The Field Museum of Natural History.)

Biting Flies Prefer Specific Bats

“In these caves, I’d see all these different bat species or even taxonomic families roosting side by side. Some of them were loaded with bat flies, while others had none or only a few,” Lutz said in Phys.org. “And these flies are typically very specific to different kinds of bats—you won’t find a fly that normally feeds on horseshoe bats crawling around on a fruit bat. I started wondering why the flies are so particular. Clearly, they can crawl over from one kind of bat to another, but they don’t really seem to be doing that.”

The researchers suspected that the bacteria contained in the skin microbiomes of individual bats could be influencing which bats the flies selected to bite. The bacteria produce a distinctive odor which may make certain bats more attractive to the flies.

The type of fly assessed for the study are related to mosquitoes and most of them are incapable of flight.

“They have incredibly reduced wings in many cases and can’t actually fly,” Lutz explained. “And they have reduced eyesight, so they probably aren’t really operating by vision. So, some other sensory mechanisms must be at play, maybe a sense of smell or an ability to detect chemical cues.”

To test their hypothesis, the research team collected skin and fur samples from the bodies and wings of a variety of bat species located in various caves around Kenya and Uganda. They collected their samples at 14 field sites from August to October in 2016. They then examined the DNA of the bats as well as the microbes residing on the animals’ skin and searched for the presence of flies.

“The flies are exquisitely evolved to stay on their bat,” said Carl Dick, PhD, a professor of biology at Western Kentucky University and one of the study’s authors. “They have special combs, spines, and claws that hold them in place in the fur, and they can run quickly in any direction to evade the biting and scratching of the bats, or the efforts by researchers to capture them,” he told Phys.org.

“You brush the bats’ fur with your forceps, and it’s like you’re chasing the fastest little spider,” Lutz said. “The flies can disappear in a split second. They are fascinatingly creepy.”

Genetic Sequencing DNA of Bat Skin Bacteria

After collecting their specimens, the researchers extracted DNA from the collected bacteria and performed genetic sequencing on the samples. They created libraries of the bacteria contained in each skin sample and used bioinformatics methods to identify the bacteria and compare the samples from bats that had flies versus those that did not.

“How the flies actually locate and find their bats has previously been something of a mystery,” Dick noted. “But because most bat flies live and feed on only one bat species, it’s clear that they somehow find the right host.”

The scientists discovered that different bat families did have their own distinctive skin microbiome, even among samples collected from different locations. They found that differences in the skin microbiomes of certain bats does contribute to whether those bats have parasites. But not all their questions were answered.

“We weren’t able to collect the actual chemicals producing cue—secondary metabolites or volatile organic compounds—during this initial work. Without that information, we can’t definitively say that the bacteria are leading the flies to their hosts,” Lutz said.

Next Steps

“So, next steps will be to sample bats in a way that we can actually tie these compounds to the bacteria. In science, there is always a next step,” she added.

This research illustrates that there may be a reason why certain animals and humans tend to be more attractive to insects than others. It is also possible that an individual’s skin microbiome may explain why some people are more prone to mosquito and other types of insect bites.

More research and clinical studies on this topic are needed, but it could possibly lead to a clinical laboratory test to determine if an individual’s skin microbiome could contribute to his or her potential to being bitten by insects. Such a test would be quite beneficial, as insects can carry a variety of diseases that are harmful to humans.

Perhaps a precision medicine therapy could be developed to alter a person’s microbiome to make them invisible to blood-sucking insects. That would be a boon to regions of the world were diseases like malaria are spread by insect bites.

—JP Schlingman

Related Information:

Blood-sucking Flies May Be Following Chemicals Produced by Skin Bacteria to Locate Bats to Feed on

Associations Between Afrotropical Bats, Eukaryotic Parasites, and Microbial Symbionts

The Human Skin Microbiome

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