First case of Listeria monocytogenes causing peripheral neurological complications

An old woman was admitted to the emergency room with a body temperature of 39 degree celsius, normal pulse, elevated blood pressure and respiratory rate of 24/min. Lumbar puncture was done and it revealed that there were high level of leukocytes and protein. Glucose level was normal. PCR assay was done from cerebrospinal fluid which showed positive to Listeria monocytogenes. After 3 days of admission, the patient started to experience weakness in her right arm. At the same time the patient noticed a mild change in taste. After day 6 of admission, nerve conduction study and some tests were done. After looking at the results, they considered to diagnose with acute polyradiculoneuritis.

Nobody knows how the infection of Listeria monocytogenes led to meningoencephalitis causing polyradiculoneuritis because this is the first case. They suspect that the “molecular mimicry” played a part in the dysimmune process leading to axonal dysfunction.

References

Anon., n.d. Meningitis and Encephalitis. [Online]
Available at: https://psychpedia.blogspot.com/2014/08/meningitis-and-encephalitis.html
[Accessed 7 26 2019].

Tebib, N., Bill, O., Niederhauser, J. & Christina, L., 2018. An uncommon complication of Listeria monocytogenes infection: Polyradiculoneuritis following Listeria meningoencephalitis. [Online]
Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6010957/
[Accessed 26 7 2018].

 

 

How do some Listeria survive in food despite the high food hygiene standards

 

A newly defined “stress survival islet” asures survival of some listeria strains despite high hygiene standards in food production.
Credit: Institute of Milk Hygiene/Vetmeduni Vienna

With the high food hygiene standards, Listeria monocytogenes(Lm) is still able to persist in the food. This is due to certain genetic mechanisms which gives protection for Lm from cleaning chemicals. In the genome, there are hypervariable regions which contain genetic inserts such as stress survival islet 1(SSI-1). SSI-1 allows Lm to survive under certain stressful environment. However, this does not demonstrates how it is able to survive the hygiene standards such as the alkaline and oxidative treatment. To unlock the mystery behind it, researchers conducted experiments and identified 2 gene that contributed to Lm survival in alkaline and oxidative environment. The first gene is the transcriptional regulator which regulates the second protein under certain situations and the second gene is the protease which breaks down proteins. In stress situations, unfunctional proteins are created where it is broken down by protease. Hence, both genes make up a functional unit which is identified as stress survival islet 2. Due to this, it is able to survive under alkaline and oxidative environment.

References

Veterinärmedizinische Universität Wien, 2017. An island getaway: Why some Listeria strains survive good food hygiene standards. [Online]
Available at: https://www.sciencedaily.com/releases/2017/08/170830095024.htm
[Accessed 22 7 2018].

 

Detection of Listeria Monocytogenes

In the past, methods for detecting Listeria Monocytogenes from foods and for confirmation, was through prolonged incubation and biochemical testing. These methods requires up to four to five days to obtain results.

However, in a current study, it has shown that a simple and rapid proteomics-based MALDI-TOF MS approach was developed to detect L. monocytogenes directly from selective enrichment broths. Milk samples spiked with single or multiple species were incubated in a selective enrichment broth for 24 hours, followed by a 6 hours secondary enrichment. Low amounts of colony-forming unit (cfu) of Listeria monocytogenes were detected in the first 30 hours.

They have also carried out the same procedures for solid foods, namely, chicken pâté, cantaloupe and Camembert cheese were used. Detection was achieved by using this method. This new detection method saves time and money for a more direct identification of Listeria monocytogenes.

Listeria monocytogenes have the potential to cause major illnesses and fatalities in humans. Hence, continual development of new methods for detection is essential. Therefore, this method presents itself as a useful tool to detecting the major food-borne pathogen, Listeria monocytogenes.

References

S, J., D, S., M, B. & EA, P., 2014. Detection of Listeria monocytogenes from selective enrichment broth using MALDI-TOF Mass Spectrometry. [Online]
Available at: https://www.ncbi.nlm.nih.gov/pubmed/24080423
[Accessed 25 7 2018].

 

Newly Found Way to Fight Listeria

Scientists has known that by inhibiting an enzyme known as glucose-1-phosphate uridylyltransferase (GalU) can alter the bacteria’s, L. monocytogenes, cell surface dramatically. These alterations will lead to the bacteria being less virulent.

By using computers and cheminformatics methods, the scientists have found 37 compounds that could potentially inhibit GalU while only 3 of them are effective enough to call for further studies.

Another interesting thing that the scientist have found out is that by inhibiting GalU, L. monocytogenes seems to be more vulnerable to cefotaxime, an antibiotic which the bacteria is naturally resistant to.

References:

DESK, N., 2018. Scientists may have new weapon to fight Listeria. [Online]

Available at: http://www.foodsafetynews.com/2018/03/researchers-may-have-found-new-way-to-fight-drug-resistant-bacteria/#.W1SXSNUzbIU

[Accessed 14 March 2018].

 

Fats can neutralize Listeria

Healthy fatty acids can work as medicine to neutralize listeria. Professor Birgitte Kallipolitis had proved that Omega-3 fatty acids can neutralise listeria in 30 minutes. However, too low amount of fatty acid – Omega-3 will not kill the bacteria.

Their theory is that the fatty acids do something to the PrfA protein which prevents it from switching on its virulence genes.

However, by using fatty acids, the bacteria are not killed, they are rendered harmless and hence remains alive. This can be an advantage. Since the growth of the bacterium is not threatened, it does not develop resistance to attack, which many other bacteria have already developed. It may be a better plan to let them live and find ways to neutralise them instead of killing them.

Listeria may potentially be life-threatening for immunocompromised individuals, and hence poses as a threat to people.

References

University of Southern Denmark. (2017, May 23). Retrieved from https://www.sciencedaily.com/releases/2017/05/170523083333.htm

Understanding how Listeria monocytogenes is vertically transmitted

Placenta plays a important role of providing protection to the developing fetus. Listeria monocytogenes(Lm) is one of the pathogen that can pass through the placental barrier and cause damage to the fetus resulting to its death. Even with antibiotic treatment Lm is still unstoppable. Animal model, organ model and in vitro cell culture was used to aid in our understanding of its virulence. This models used will not give the complete understanding of Lm invading the human placenta as the models used does not replicate an in vivo model of human pregnancy.

An environment of balance between fetal tolerance and pathogen protection is required in pregnancy. It was implicated that Interalin (Inl) A, InlB and InlP which is some of Lm virulence factors have contributed to trophoblast infection. However, in this study it showed otherwise because it was observed that InlA had no role in invading the placenta when pregnant guinea pig was used which had the correct form of the E-cadherin receptor normally bound by InlA. Such different results may due to the fact of limitations in current animal models availability. Hence, future studies to confirm the roles of Interlain is recommended.  LLO and ActA are also some of Lm virulence factors that aid in the infection and vertical transmission as those are necessary for Lm growth in placental cells. Moreover LLO and ActA, also aids Lm to spread to the fetus via cell-to-cell interactions.

References

kalidindi, D., 2015. Disease transmission and cycle. [Online]
Available at: https://www.slideshare.net/DrBharatKalidindi/disease-transmission-and-cycle
[Accessed 22 7 2018].

Lamond, N. M. & Freitag, N. E., 2018. Vertical Transmission of Listeria monocytogenes: Probing the Balance between Protection from Pathogens and Fetal Tolerance. [Online]
Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6027155/
[Accessed 22 7 2018].

 

 

Alternate plan of action for Listeria

An alternate path has been discovered for Listeria to be infected to enter the bloodstream. Generating more uncertainties within society, as forms of foodborne Listeria bacteria may now be considered more dangerous than we thought.

Listeria is often found in deli meat, hot dogs and dairy products.

The Listeria monocytogenes bacteria must cross the epithelial barrier which usually protects the bloodstream from deleterious pathogens, to infect someone. For that to happen, a protein called Internalin A, is required to break through that barrier.

According to Bhunia’s findings, reported in the journal Cell Host & Microbe, it was shown that Listeria adhesion protein (LAP) interacts with heat shock protein (HSP) in mice, resulting in the opening of epithelial cells hence giving access to internalise in the bloodstream. When LAP interacts with HSP, those cells move apart, not only giving the bacterium access to the bloodstream, but also exposing the Internalin A receptors and allowing transport of Listeria monocytogenes into the bloodstream. Thus endangering us with many symptoms such as Headache, stiff neck, confusion, loss of balance as well as convulsions.

References

Purdue University . (2018, March 30). Retrieved from https://medicalxpress.com/news/2018-03-alternate-path-listeria-sicken-people.html

Image retrieved from: https://reliawire.com/alternative-listeria-path/

Newly discovered Listeria species

A new Listeria species called Listeria costaricensis was found in the waters of an industrial drainage area in Costa Rica, province of Alajuela. It took 3 years worth of sample collections as well as in-depth research to successfully find a new species of Listeria. Consisting of 18 species is the bacterial genus Listeria. Among the 18 species, 2 of them are pathogenic to humans and animals. Through the consumption of contaminated food, Listeria monocytogenes, causes gastroenteritis, septicemia and central nervous system (CNS) infection. These diseases/infections commonly infect immunocompromised individuals and causes fetal and neonatal infection.  

Luckily, the new species Listeria costaricensis is a type of non-pathogenic bacteria, however, its discovery will definitely increase our understanding of the harmful potential of Listeria species that are pathogenic. “The discovery of Listeria costaricensis will allow comparisons with pathogenic Listeria species, in order to better understand the behavior and adaptations of these bacterial pathogens,” quoted by TEC biotechnologist Kattia Núñez.

References

Institut Pasteur. (2018, April 17). Retrieved from https://www.sciencedaily.com/releases/2018/04/180417130106.htm

Image retrieved from: https://www.elpais.cr/2018/02/22/cientificos-de-costa-rica-descubren-nueva-bacteria-que-no-es-danina/

 

Presence of Listeria strands in Pet Food

 

Radagest Pet Food Inc. of Portland, OR, has recently recalled their raw cat food back due to the possibility of having listeria monocytogenes. It was recalled along with the likelihood of the presence of Escherichia Coli, which was also detected during the testing.

Although this cat food causes poisoning for cats, it may also infect people when they deal with contaminated food or surfaces. Hence, these deadly pathogens can be transferred to humans since food is prepared at the same area.

Consumers are advised to return these to them and receive a full refund. Furthermore, pets with symptoms of a listeria monocytogenes infection, should contact their veterinarian.

 

References

Entis.Phyllis. (2018, July 10). Retrieved from http://www.foodsafetynews.com/2018/07/listeria-e-coli-contamination-triggers-recall-of-raw-pet-food/#.W0jAi9IzbIV

Listeria in frozen vegetables again?

Following the previous blog entries about frozen vegetable, more of the products have been recalled from the UK supermarket stores due to concerns with the contamination of listeria.

Aldi, Lidl, Iceland, Sainsbury’s, Tesco and Waitrose, recalled a variety of frozen vegetable products last week because they possibly contain the bacteria Listeria monocytogenes, which causes Listeriosis. Lidl’s Greengrocers Carrots, Broccoli & Sweet Corn, Baby Carrots, Peas, Green Beans & Sweetcorn and Green Grocers Golden Vegetable Rice have been added to the list, in addition to the list of more than 40 items initially recalled.

The FSA (Food Safety Authority) warned that the product could be contaminated, and advised anyone who has purchased the item to return it to the store for a full refund.

Following the FSA, the symptoms caused by Listeria monocytogenes “can be similar to flu and include high temperature, muscle ache or pain, chills, feeling or being sick and diarrhea”.

References

Morrison, C. (2018, July 9). Retrieved from https://www.independent.co.uk/news/business/news/listeria-outbreak-frozen-vegetables-lidl-aldi-tesco-sainsburys-iceland-waitrose-a8438931.html

Image retrieved from: https://www.snopes.com/news/2018/07/07/uk-supermarkets-recall-frozen-vegetables-listeria-concerns/