The function of new microRNAs identified in Salmonella and Shigella infections

I had this prof back in my undergraduate genetics days who prayed at the church of RNA.

He may have been right.

He was an asshole.

MicroRNAs are small RNA molecules that do not code for proteins, however, they take care of an essential function: they act as regulators in gene expression, and so they have become a focus of attention for medical science. Despite there being thousands of different sequences of this genetic material, the individual role that each one plays in several illnesses continues to be unknown for the most part.

Recently, research done at the University of Cordoba, among other places, and published in Nature Microbiology, was able to determine the specific function of certain microRNAs in Salmonella Typhimurium and Shigella flexneri infections. These are two similar bacteria that are passed on to humans upon ingesting food or water infected by people or animals with the disease.

These are two intracellular pathogens that invade healthy cells and cause similar symptoms. Nevertheless, in spite of their many similarities, the results show that infections from these two bacteria are controlled by different microRNAs that have a radically opposite function.

In order to come to this conclusion, an array of over 1,400 different microRNAs were studied individually so as to verify what effect they produce in cells upon being infected by these two bacteria, explains University of Cordoba Genetics Department researcher Sara Zaldívar.

In the case of Shigella, the results show that upon infection, three specific kinds of microRNA silence the expression of the gene responsible for spreading the bacteria within the infected organism by means of filaments called filopodia. This is an immune response mechanism of the infected organism that, as a result, lessens the bacteria’s movement.

In the case of Salmonella, almost the opposite occurs. Once the cell is infected, a kind of microRNA activates the expression of a gene responsible for the bacteria reproducing. This is the pathogen’s attack mechanism in order to reproduce, something that was not only demonstrated in the laboratory but also was corroborated in vivo in pig intestinal mucosa.

The results show two mechanisms of how microRNAs act in completely different ways and that were not described ever before. While in some infections, such as Shigella, these small molecules of genetic material perform a function in the immune response of the infected organism, in others, like Salmonella, they are part of the strategies developed by the bacterium to benefit itself in order to reproduce.

One of the main takeaways from the research, as pointed out by another author, Professor Juan José Garrido, is the need to understand the specific response mechanisms of each pathogen so as to not err by extrapolating treatment. “If we do not know exactly how microRNA regulation works, then we are blindly assigning treatment and we will end up haphazardly using a wide range of antibiotics that build up resistance to the bacteria”, says the researcher. “In our laboratory alone”, adds Sara Zaldívar, “we have strains of Salmonella that have built up resistance to 14 different antibiotics”. For this reason, knowing about the mechanisms of each pathogen in particular is key to developing more effective drugs by means of searching for target genes involved in the process.

Researchers uncover early adherence step in intestinal transit of shigella

The bacterial pathogen Shigella, often spread through contaminated food or water, is a leading cause of mortality in both children and older adults in the developing world. Although scientists have been studying Shigella for decades, no effective vaccine has been developed, and the pathogen has acquired resistance to many antibiotics. The recent discovery of an early adherence step in the infection cycle by researchers at Massachusetts General Hospital (MGH) could provide a new therapeutic target or even a new method for vaccine development.

As it moves through the digestive system, Shigella traverses the small intestine and subsequently infects the large intestine, causing cramping, diarrhea and dehydration in the disease called shigellosis.

“We wanted to determine how Shigella makes its first contact with epithelial cells in the early stages of disease development,” says Dr. Christina Faherty, senior author on the study published in mSphere. “Because of certain gene sequence annotations, and the way that Shigella appeared following growth in standard laboratory media, it was believed that Shigella strains do not produce fimbriae or other adherence factors.” Fimbriae are short hair-like fibers that bacterial cells use to adhere to individual epithelial cells to instigate infection.

The work of Faherty and the research team has uncovered evidence of fimbriae that aid adherence to epithelial cells, an important step in the start of a shigellosis infection. “We mimicked the conditions that Shigella would face in its journey through the small intestine by adding bile salts and glucose to laboratory media,” says Faherty. “With this method, we discovered what had been hidden in plain sight before–the gene expression profiles that enabled Shigella to initiate this early step in infection by attaching to the epithelial tissue of the host.”

Large shigellosis outbreak at wedding

My cousin of Barrie’s Asparagus is in the midst of the annual crop in southern Ontario, and I know they have good food safety because my students have checked them out in years past and, I’m his cousin.

Unfortunately not all growers are as diligent and any commodity can get branded as shit.

Specifically, Shigella shit.

Findings presented at the CDC’s Epidemic Intelligence Service, or EIS, conference last month found that contaminated asparagus was the likely source of an outbreak of shigellosis at a wedding party in Oregon that sickened 112 people.

The outbreak was caused by Shigella flexneri type 3a, which accounts for less than 3% of S.flexneri isolates in the United States, researchers said.

“This was one of the largest foodborne outbreaks of shigellosis in U.S. history,” Steven I. Rekant, DVM, MPH, an EIS officer with the Oregon Public Health Authority, said in a presentation. “It was the second largest ever attributed to Shigella flexneri and that type of Shigella flexneri, type 3a, is uncommon in Oregon.”

According to Rekant and colleagues, the Oregon Health Authority received reports of gastroenteritis among attendees at a wedding in August 2018 and identified S. flexneri type 3a in stool samples.

A total of 263 people attended the wedding, and 75% responded to the survey. The patients were aged 2 to 93 years, and 55% were female.

“Simply put, this was big outbreak — 112 cases were reported, with an overall attack rate of 55.7%,” Rekant said.

Of 95 patients with onset information, 97% reported illness 12 to 72 hours following the wedding. Additionally, 57 patients presented to a health care facility and 10 were hospitalized, including a 92-year-old woman. No deaths or additional cases were reported.

The investigators found that only asparagus consumption was associated with illness.

They pointed to poor hygiene on the part of the food-handler as the “likely cause of contamination.”

Rekant SI, et al. Shigellosis at a Wedding — Oregon, 2018. Presented at: Epidemic Intelligence Service conference; April 29-May 2, 2019; Atlanta.

Septin proteins act as cellular police to identify, imprison and kill Shigella

A team, led by the London School of Hygiene & Tropical Medicine, has uncovered the strongest evidence yet that septins take Shigella prisoner.

It reveals for the first time that these proteins can detect where bacteria will split for division and prevent it from doing so by forming cage-like structures around the bacteria.

The research team say that although septins are a powerful, natural mechanism to restrict Shigella, future work is required to determine how septin biology can be harnessed for therapeutic purposes. It is hoped that these new findings may lead to a novel way to boost the human immune system and treat a wide variety of bacterial infections.

Lead author Professor Serge Mostowy from the London School of Hygiene & Tropical Medicine said: “We are actively working to engineer this discovery for human health application. If we can use drugs to boost septin caging, we have a new way to stop infection.”

In 2010, researchers first observed that septin cages can entrap Shigella, opening up the tantalising prospect of a new way to stop the bacteria spreading in the body. However, how cells recognise Shigella for entrapment, and the fate of entrapped bacteria, was mostly unknown.

The authors acknowledge limitations of the study including the possibility that some bacteria have evolved to avoid septin cage entrapment, and the need for in vivo study prior to application in humans.

At least 40 sick with Shigella after ‘eating food contaminated with feces at potluck birthday party’ in North Carolina

I’m not a big fan of the potluck.

Sure I get social aspect, the trying different foods and experiencing different cultures.

But do I trust the different food prep places, proper temperatures, storage and cleanliness.

Jane Wester of the Charlotte Observer reports at least 40 people are sick after eating contaminated food at a potluck birthday party in east Charlotte Saturday, Mecklenburg County health department officials said Monday.

Someone who prepared food for the party did not wash their hands well enough, Health Director Gibbie Harris said. Some partygoers are infected with a “highly contagious” disease called shigella, which causes diarrhea and is spread through feces, Harris said.

About 100 people attended the birthday party, and more may still get sick, as symptoms of shigella can take one to three days to show up after someone is infected, Communicable Disease Control director Carmel Clements said. It’s possible, however, for some people to get sick a whole week later, Clements said.

Most patients called 911 from the Forest Hills apartment complex, near where the party was held, according to Medic.

Health officials are sure that the contaminated dish was prepared in someone’s home rather than a restaurant, Harris said, because the only outside food at the party was the birthday cake.

Shigella in Kansas: Proper handwashing requires proper tools

There was this one time, when I was in Kansas, and there was an outbreak of something at the local high school.

Stalker alert: I went to the boys’ bathroom.

No paper towel. No soap.

Proper handwashing requires access to proper tools.

The Shawnee County Health Department and KDHE are checking several shigellosis cases in children.

USD 501 confirms it centers on Highland Park Central Elementary, saying the district sent information to those parents.

Shigellosis is a gastro intestinal illness caused by a bacteria.

It is treatable and most people quickly recover from symptoms including diarrhea, fever, nausea, vomiting, and stomach cramps.

Shigella is found in the feces of an infected person. It’s spread by close contact, and by eating and drinking contaminated food or water.

To stop the spread, always wash your hands thoroughly with soap and water before eating. Do not share food, drinks, spoons and or straws.

No paper towel. No soap.

Proper handwashing requires access to proper tools.

Those are the kinds of questions that get full professors fired.

Shigellosis outbreak in Flint, Mich. because people afraid to wash hands

Don’t eat poop (and if you do, make sure it’s cooked).

Wash your hands.

handwash_south_park2These are the basics of public health.

Most of us are taught from a very early age that hand-washing is an easy, essential way of keeping ourselves clean and healthy. But residents of Flint, Michigan and surrounding areas have been forgoing this common practice out of fear of the water’s toxicity. Genesee county, of which Flint is a the largest city, and the adjacent county of Saginaw combined have experienced an outbreak of 131 cases of Shigellosis (named after the bacteria that causes it, Shigella). It’s a bloody diarrheal disease transmitted via tiny amounts of contaminated fecal matter. It typically lasts about a week, but can also cause patients to feel like they have to go to the bathroom even when they have no more waste in their systems. Additionally, the US Centers for Disease Control (CDC) also notes that “may be several months before [patients] bowel habits are entirely normal.”

In 2013, there were just under five cases reported per every 100,000 people in America. The outbreak in Michigan far exceeds that number, and it’s likely because residents in the area are afraid to use their tap water, which was found to have toxic levels of lead, a heavy metal that can cause neurological problems when it builds up in the body, in 2015. Even though the water was deemed safe for consumption with a proper filter, people in the area are still scared to wash their hands at all, according to the Washington Post.

Instead, they’re cleaning themselves using baby wipes—aren’t nearly as effective as disinfectant as good old-fashioned scrubbing—which should take about 20 seconds to ensure that any potential pathogens are washed down the drain.

“Some people have mentioned that they’re not going to expose their children to the water again,” Jim Henry, Genesee County’s environmental health supervisor, told CNN.

 

Shigella blooms in South Central Idaho

South Central Public Health District warns the community of increases cases of infectious disease Shigellosis, also known as Shigella, in South Central Idaho Thursday.

my.own.private.idahoIn 2015, 17 cases of Shigellosis were reported in the region. Since the beginning of 2016, 14 cases have been reported. The infectious disease has been reported in Blaine, Minidoka, Twin Falls and Jerome counties.

“Many people are unfamiliar with Shigella and what causes it,” said Tanis Maxwell, SCPHD Epidemiologist, in a news release. “Shigella is a bacteria present in the fecal matter of an infected individual. The symptoms of Shigella are watery or bloody diarrhea, abdominal pain, and fever.”

Restaurant owner blames homeless restroom users for outbreak

There’s a lot of amateur epidemiology going on this week. The latest comes from the owner of San Jose’s Mariscos San Juan #3, which reopened yesterday after being linked to 182 illnesses including 12 hospitalizations.

According to ABC 7, owner Segio Cruz says that homeless individuals using his restroom may have introduced the pathogen. Public health folks believe it was a food handler.1052002_630x354

“This is first time this happened in my store, I opened my store in 2000,” said Segio Cruz, the restaurant owner.

Cruz owns three restaurants. He says since the shigella outbreak, business has dropped off 70 percent. He says even more damaging is the negative reputation generated by the incident, which he feels his restaurant does not deserve. “You can get sick in your house, your office, anywhere,” insists Cruz.

Cruz said homeless people often use the bathroom inside his restaurant and that perhaps could be another contributing factor. But again, there is still no definitive answers as to what caused this massive, and now mysterious, outbreak.

If his theory is correct, how did the Shigella get from the restroom to the food?

San Jose restaurant no longer gettin’ shiggy wit it

Marisco’s San Juan #3 restaurant linked to 200 cases of shigellosis is due to be open for business tomorrow according to KCRA. Although a source of the outbreak wasn’t confirmed, the working theory is that an infected food handler was to blame.

The Department of Environmental Health reinspected Marisco’s San Juan #3, which has been closed since Oct. 18, and approved it for reopening after finding it no longer poses a risk to public health from shigella bacteria, officials said.

County officials said the restaurant’s owners voluntarily discarded all food products on site, cleaned and sanitized the facility and retrained all employees in proper food handling methods. Employees who tested negative for shigella are being allowed to return to work.

Health officials determined that an outbreak of illness connected with the restaurant at 205 N. Fourth St. that caused 190 people to become sick was caused by shigella, a contagious diarrhoeal illness.

The source was most likely from an infected food handler at the restaurant who contaminated the entrees with their hands, officials said. But the exact source of the outbreak has not been determined, and officials have said it might never be identified.