Tag Archive for: bacterial

bacterial extracellular vesicle

Once overlooked cellular messengers could combat antibiotic resistance

bacterial extracellular vesicle

Children’s National Hospital researchers for the first time have isolated bacterial extracellular vesicles from the blood of healthy donors. The team theorizes that the solar eclipse lookalikes contain important signaling proteins and chromatin, DNA from the human host.

Children’s National Hospital researchers for the first time have isolated bacterial extracellular vesicles from the blood of healthy donors, a critical step to better understanding the way gut bacteria communicate with the rest of the body via the bloodstream.

For decades, researchers considered circulating bacterial extracellular vesicles as bothersome flotsam to be jettisoned as they sought to tease out how bacteria that reside in the gut whisper messages to the brain.

There is a growing appreciation that extracellular vesicles – particles that cells naturally release – actually facilitate intracellular communication.

“In the past, we thought they were garbage or noise,” says Robert J. Freishtat, M.D., MPH, associate director, Center for Genetic Medicine Research at Children’s National Research Institute. “It turns out what we throw away is not trash.”

Kylie Krohmaly, a graduate student in Dr. Freishtat’s laboratory, has isolated from blood, extracellular vesicles from Escherichia coli and Haemophilus influenzae, common bacteria that colonize the gut, and validated the results via electron microscopy.

“The images are interesting because they look like they have a bit of a halo around them or penumbra,” Krohmaly says.

The team theorizes that the solar eclipse lookalikes contain important signaling proteins and chromatin, DNA from the human host.

“It’s the first time anyone has pulled them out of blood. Detecting them is one thing. Pulling them out is a critical step to understanding the language the microbiome uses as it speaks with its human host,” Dr. Freishtat adds.

Krohmaly’s technique is so promising that the Children’s National team filed a provisional patent.

The Children’s research team has devised a way to gum up the cellular works so that bacteria no longer become antibiotic resistant. Targeted bacteria retain the ability to make antibiotic-resistance RNA, but like a relay runner dropping rather than passing a baton, the bacteria are thwarted from advancing beyond that step. And, because that gene is turned off, the bacteria are newly sensitive to antibiotics – instead of resistant bacteria multiplying like clockwork these bacteria get killed.

“Our plan is to hijack this process in order to turn off antibiotic-resistance genes in bacteria,” Dr. Freishtat says. “Ultimately, if a child who has an ear infection can no longer take amoxicillin, the antibiotic would be given in tandem with the bacteria-derived booster to turn off bacteria’s ability to become antibiotic resistant. This one-two punch could become a novel way of addressing the antibiotic resistance process.”

ISEV2020 Annual Meeting presentation
(Timing may be subject to change due to COVID-19 safety precautions)
Oral with poster session 3: Neurological & ID
Saturday May 23, 2020, 5 p.m. to 5:05 p.m. (ET)
“Detection of bacterial extracellular vesicles in blood from healthy volunteers”
Kylie Krohmaly, lead author; Claire Hoptay, co-author; Andrea Hahn, M.D., MS, infectious disease specialist and co-author; Robert J. Freishtat, M.D., MPH, associate director, Center for Genetic Medicine Research at Children’s National Research Institute and senior author.

electronic cigarette dispenser with different flavors of nicotine

Extreme difficulty breathing and swallowing linked to teen’s vaping?

electronic cigarette dispenser with different flavors of nicotine

After a teen was transferred to Children’s National Hospital suffering from severe difficulty breathing and swallowing, a multidisciplinary team continued the detective work and surmises that vaping was to blame for her unusual symptoms.

A teenage girl with no hint of prior asthma or respiratory illness began to feel hoarseness in her throat and a feeling that she needed to clear her throat frequently. Within a few weeks, her hoarseness and throat-clearing worsened with early morning voice loss and feeling as if food were lodged in her throat. She started having trouble swallowing and began to avoid food all together.

Her pediatrician prescribed loratadine for suspected allergies to no avail. Days later, an urgent care center prescribed a three-day course of prednisone. For a few days, she felt a little better, but went back to feeling like she was breathing “through a straw.” After going to an emergency room with acute respiratory distress and severe difficulty swallowing, staff tried intravenous dexamethasone, ampicillin/sulbactam, and inhaled racemic epinephrine and arranged for transfer.

When she arrived at Children’s National Hospital, a multidisciplinary team continued the detective work with additional testing, imaging and bloodwork.

Examining her throat confirmed moderate swelling and a partially obstructed airway draped with thick chartreuse-colored mucus. The teen had no history of an autoimmune disorder, no international travel and no exposure to animals. She had no fever and had received all her scheduled immunizations.

“With epiglottitis – an inflammation of the flap found at the base of the tongue that prevents food from entering the trachea – our first concern is that an underlying infection is to blame,” says Michael Jason Bozzella, D.O., MS, a third-year infectious diseases fellow and lead author of the case report published Feb. 5, 2020, in Pediatrics. “We tested her specimens in a number of ways for a host of respiratory pathogens, including human rhino/enterovirus, respiratory syncytial virus, influenza, Epstein-Barr virus, Streptococcus and more. All negative. We also looked for more atypical infections with bacteria, like Arcanobacterium, Mycoplasma and Gonorrhea. Those were all negative as well,” Dr. Bozzella adds.

She slowly improved during a seven-day initial hospital stay, though soon returned for another six-day hospital stay after it again became excruciatingly painful for her to swallow.

Every throat culture and biopsy result showed no evidence of fungal, bacterial or viral infection, acid-fast bacilli or other malignancy. But in speaking with doctors, the teen had admitted to using candy-and fruit-flavored e-cigarettes three to five times with her friends over the two months preceding her symptoms. The last time she vaped was two weeks before her unusual symptoms began.

According to the Centers for Disease Control and Prevention, 2,668 people in the U.S. have been hospitalized for e-cigarette or vaping product use-associated lung injury, as of Jan. 14, 2020. The Children’s National case report’s authors say the increasing use of vaping products by teenagers highlights the potential for unknown health risks to continue to grow.

“This teenager’s use of e-cigarettes is the most plausible reason for this subacute epiglottitis diagnosis, a condition that can become life-threatening,” says Kathleen Ferrer, M.D., a hospitalist at Children’s National and the case report’s senior author. “This unusual case adds to a growing list of toxic effects attributable to vaping. While we normally investigate infectious triggers, like Streptococci, Staphylococci and Haemophilus, we and other health care providers should also consider e-cigarettes as we evaluate oro-respiratory complaints.”

In addition to Drs. Bozzella and Ferrer, Children’s National case report co-authors include Matthew Allen Magyar, M.D., a hospitalist; and Roberta L. DeBiasi, M.D., MS, chief of the Division of Pediatric Infectious Diseases.

Parasite collage

Which micro-organisms lurk within urine?