Back to the Basics!

To understand the significance of Haemophilus influenzae and how it can become a destructive bacterial infection, we must first review the basics of this microbe. Being able to recognize the cellular structure of H. influenzae will be essential in the future when discussing how this microbe manifests into different diseases, why these infections can be difficult to treat and how the Hib vaccine functions.

H. influenzae is gram-negative coccobacillus. Gram-negative bacteria differ from gram-positive, because they have an outer membrane that provides additional protection. This membrane can also protect bacteria like H. influenzae from lysozymes, which is a natural defense mechanism of the body.

Photomicrograph of H. influenzae as seen using gram-stain technique. (CDC, 2016)

Gram-negative bacteria get increased attention because they are commonly a concern in regard to treating these nasty infections. This type of bacteria can become resistant to multiple drugs due to their ability to efficiently pass genetic information and hide from the host immune response.

 

This ability to evade defense mechanisms is also largely due to the capsule that surrounds many of these gram-negative bacteria. There are six different types of H. influenzae with capsules (a-f) that I briefly explained in the previous blog. A capsule is a thick layer of polysaccharides that numerous pathogens use to protect themselves from the host defense system. Bacteria with capsules are protected because phagocytic cells cannot always recognize these encapsulated microbes, so they are not destroyed. (Charles, 2013) Often host cells recognize invaders by the antigens found on bacteria cells. These capsules can lessen antigen presentation preventing bacteria cells from being recognized by the immune system. In addition, capsules help block opsonization, which interferes with phagocytosis. Capsules also can help in the process of forming biofilms, which is another reason why bacteria can be difficult to treat. All of these reasons explain why strains with capsules tend to cause more invasive infections. (Apicella, 2009)

As we continue to learn more about H. influenzae we will be able to apply this basic knowledge that we talked about to broader concepts. Next week we will explore who is at an increased risk for H. influenzae disease and the distribution of the diseases that are cause by encapsulated versus unencapsulated H. influenzae bacteria.

 

 

 

Apicella, M. A., Johnston, J. W. 2009. Haemophilus influenzae. Encyclopedia of Microbiology (Third Edition). Academic Press. 153-162. Retrieved from:

http://www.sciencedirect.com/science/article/pii/B9780123739445001747

 

Charles, T., DuPont, C., Wessner, D. Year. Microbiology 1st Edition. 2013. John Wiley & Sons, Inc., New Jersey.

 

Centers for Disease Control and Prevention (CDC). Department of Health and Human Service. 2016. Haemophilus influenzae Disease (Including Hib).

https://www.cdc.gov/hi-disease/about/index.html

 

 

Introduction to Haemophilus influenzae.

(Posted on September 25th 2017 on mypetmicrobe.worldpress.com -Blog #1)

Interesting enough, Haemophilus influenzae bacteria can commonly be found in the nose and throat of healthy individuals. Although this bacterium is typically not harmful to us, the focus is predominantly on when this microbe goes rouge and causes mild to severe bacterial infections in the body. Severe issues can occur when this bacterium becomes invasive and moves to other parts of the body, such as the lungs, bloodstream or the central nervous system. To understand this microbes’ significance, I will begin by examining a brief overview of the history of H. influenzae and the major categories of this bacteria.

H. influenzae use to be referred to as Bacillus influenzae or Pfeiffer’s bacillus in the late 19^th and early 20^th centuries. In 1892 physician and bacteriologist Richard Pfeiffer and Shibasaburo Kitasato reported a new bacterium that was said to be the cause of pandemic influenza. Later their findings would be debated because it was not universally found in all influenza cases in these studies concerning individuals effected by the outbreaks (Hultin, 2007). This new microbe was thought to be the cause of influenza until 1918, when another pandemic occurred and scientists performed experiments. During these experiments, they discovered that the infective agent remained even after it was passed through a filter, which had pores that were too small to allow the H. influenzae bacteria to pass through (Hultin, 2007). This contradicted Pfeiffer’s original hypothesis of H. influenzae being the primary cause of influenza. The infective agent responsible for influenza would later be discovered to be a virus. Even though this discovered bacterium continues to be named H. influenzae, it is not the cause of influenza, but rather is associated with this sickness as a “secondary bacterial invader” (Wollstein, 1919). As time continued research findings uncovered new insights into this unfamiliar microbe, H. influenzae.

There are two main categories of H. influenzae bacteria, encapsulated and unencapsulated. The encapsulated bacteria, also known as typeable, include six serotypes (a-f) that differ in their capsular polysaccharides (CDC, 2006). The most well-known type is H. influenzae type b (Hib), which I will refer to in future blog posts. The other serotype is non-typeable, which are the unencapsulated H. influenzae. Differentiating between these types will become important as I talk about the various cellular structures and how they affect the range of diseases and treatments.

As this blog continues, we will explore more details of the characteristics of H. influenzae. Details include: structure and how it functions, and the diseases it causes in the human body. The key component to examining what effect this microbe has on us, will be understanding how it is transmitted and how it becomes invasive.  After this, I will discuss how to prevent and treat infections caused by this bacterium.

 

 

 

 

Centers for Disease Control and Prevention (CDC). Department of Health and Human Service. 2016. Haemophilus influenzae Disease (Including Hib).

https://www.cdc.gov/hi-disease/about/index.html

 

Hultin, J. V., Morens, D. M., Taubenberger, J. K. 2007. Discovery and Characterization of the 1918 Pandemic Influenza Virus in Historical Context. Antiviral Therapy. 12(4): 581-591. Retrieved from:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2391305/

 

Wollstein, M. 1919. Pheiffer’s Bacillus and Influenza. The Rockefeller University Press. Retrieved from:

http://jem.rupress.org/content/jem/30/6/555.full.pdf

 

Vibrio Cholerae: a Harrowing Infection

Vibrio cholerae thrives in unsanitary conditions, which leads to one of the most gruesome intestinal infections possible. V. cholerae causes cholera; a severe epithelial intestinal infection that leads to severe diarrhea, often fatal due to the loss of electrolytes and hydration. In 1994 cholera cases were notified from 94 countries—the highest ever number of countries in one year (World Health Organization, 1995). A new estimate illustrates 2.9 million of cases and 95,000 deaths in 69 endemic countries, with the majority of the burden in Sub-Saharan Africa (Ali et al. 2015).

In the last two decades, we do see a slight improvement of the cholera situation. Still, majority of this concern lies with third world countries where food and water contamination play the largest role in the spread of cholera. Poor water-supply and sanitation facilities often create breeding grounds for these epidemics. When adding refugee camps to the equation from warring countries (such as Rwanda), we see outburst of this hard-to-treat bacteria.

http://www.who.int/features/factfiles/cholera/en/

Figure 1. A peri-urban slum in sub-Saharan Africa where cholera thrives within the population.

 

http://www.premiumtimesng.com/news/more-news/234979-5-6-million-children-lake-chad-region-risk-waterborne-diseases-rainy-season-starts-unicef.html

Figure 2. Children collecting water near the Lake Chad Basin (sub-Saharan Africa), where unsanitary water conditions are a direct pathway for V. cholerae.

Cholera is not something to be taken lightly. This bacteria falls within the gram-negative realm, where antibiotics already have little to no effect. If it is not managed properly, this bacteria could easily turn into a world-wide pandemic. Stay tuned for next week for more on V. cholerae!

 

• Hayden Swartz 9/29/17

 

Bibliography

Ali M, Nelson AR, Lopez AL, Sack DA. Updated Global Burden of Cholera in Endemic Countries. PLoS Neglected Tropical Diseases. 2015 Jun [accessed 2017 Sep 29]. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4455997/

World Health Organization (1995). Cholera in 1994. Weekly Epidemiological
Record, 70:201–208.

A Brief Overview of “Mycobacterium tuberculosis”

Figure 1. Scanning electron micrograph of Mycobacterium tuberculosis bacteria, NIAID, March 27, 2017

Tuberculosis (TB) is a disease that has wreaked havoc on the human population since before the earliest human recorded history. Early recordings from Assyrian tablets in the 7^th century describe patients with symptoms such as severe coughing, coughing blood, chest pain and “wasting away” (Smith, 2003). According to the Global Tuberculosis Institute, common symptoms of TB infection in the lungs are; a bad cough lasting longer than 2 weeks, pain in the chest, and coughing up blood or sputum. Symptoms where TB infects other areas of the body include weakness or fatigue, loss of appetite and weight loss (RGIF, 2015), which resembles the description from the Assyrian tablets of “wasting away”. Such early recordings show that the disease has made a significant impact on Eastern societies and continue to do so to this day (Smith, 2003). Around 9 million people are infected with TB worldwide and an estimated 2-3 million people die every year from this disease (RGIF, 2015).

Figure 2. Dr. Robert Koch

Thanks to the work of Robert Koch and the many great scientists who have come before and after him the bacteria responsible for this horrific disease has been discovered and its complete genome has been sequenced; Mycobacterium tuberculosis. Though this bacterium mainly targets the lung it can be found elsewhere in the body such as bone, lymph nodes, nervous system, and other organ systems (Smith, 2003). This bacterium is transferrable only through the air via coughing, sneezing or close interactions with an infected individual, however, due to the bacterium’s slow reproduction rate individual’s immune system may be able to fend off the bacterium. However, not every individual is so lucky and the disease may develop at a later time if they do not receive the proper medical care (RGIF, 2015).

This blog will take us on a journey of M. tuberculosis as we try to understand its significance and function in the world. Thanks to the complete genome sequencing, we will be able dive into the ancient history of the bacterium to try to understand its evolution and how it came to be the significant bacterium we know today. We will look at recent history and the people responsible for the discovery of M. tuberculosis as well as several genes responsible for virulence and infection in humans and animals. We will also be exploring the function and structure of the bacterium to better understand the interactions of the bacterium in relation to its metabolism and affects on human physiology. And lastly, we will look into future research of M. tuberculosis and questions that we have yet to know the answer to, including ways to study the interactions of M. tuberculosis within the host and macrophages within the lung.

 

Smith, I. 2003. Mycobacterium tuberculosis Pathogenesis and Molecular Determinants of Virulence. Clinical Microbiology Reviews. 16(3): 463-496 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC164219/

Rutgers Global Tuberculosis Institute (RGIF). 2015. About TB. Retrieved September 17, 2017, from http://globaltb.njms.rutgers.edu/abouttb/tbfaq-intro.html

Image 1: Scanning Electron Micrograph of Mycobacterium tuberculosis. Retreived September 17, 2017.  https://www.niaid.nih.gov/diseases-conditions/tuberculosis-tb

Image 2. Robert Koch. https://www.thefamouspeople.com/profiles/robert-koch-6563.php

Cytomegalovirus- an introduction from a medical standpoint

In this first post, I intend on approaching the topic from a medical standpoint, speaking about the signs, symptoms, and affected populations. Cytomegalovirus, or CMV, is a common virus. It stems from the same place where the chicken pox do. Most adults will have had this virus at one point in their lives. Once the virus is contracted, it remains in the system for life. CMV hardly causes symptoms in healthy individuals, so why do we care about it? We want to know that this exists and how it works because of the many individuals who do not have healthy immune systems or fully functioning immune systems. People may think this is only those who are born with deficient immune systems however, pregnant women and infants also have weaker immune systems than the average male or female. For these individuals, CMV can cause immense harm.

CMV is transmitted through bodily fluids. This is another reason why pregnant women are cause for more concern. If contracted while pregnant, CMV can be passed to the unborn child as well as being passed to a child through breast milk. Other individuals at risk are those with HIV or recent organ transplant recipients. For babies who contract this through the womb, symptoms may not be present at birth however if some should appear, jaundice (a yellow discoloration) of the skin and whites of the eyes is the most common symptom along with premature or low birth weight. For infants who contract this after being born, through something like breast milk, the symptoms are more severe and can even cause neural damage.

While CMV is most commonly contracted during childhood, symptoms can reappear during adulthood as the virus is present consistently once an individual has already had it. Not experiencing symptoms means that the virus is lying “dormant” or not being active due to not having a host as viruses need to thrive. For those healthy adults and children that experience CMV symptoms they are usually mild cold and flu like symptoms such as fever, cough, and sore throat. For those who have compromised immune systems due to an illness like HIV mentioned above or due to a recent organ transplant, the symptoms are more severe and can affect all parts of the body due to the inability of the body to fight off the virus. The most common affected areas for these people are the eyes, lungs, liver, brain, stomach, and esophagus.

Sources:

1. Papadopol, Raluca MD (2014). Infections: Cytomegalovirus. Kids Health. http://kidshealth.org/en/parents/cytomegalovirus.html#
2. Mayo Clinic Staff (2017). Cytomegalovirus (CMV) Infection. Mayo Clinic. http://www.mayoclinic.org/diseases-conditions/cmv/diagnosis-treatment/diagnosis/dxc-20315478

The Salmonella typhi Tribune

Why we wash our hands

We’ve all learned from an early age that we need to wash our hands after going to the bathroom. Why is that exactly? Of course the obvious fact is that it significantly slows the spread of germs, but Salmonella typhi  is one of the microorganisms largely responsible for the education we have today. 

Salmonella enterica typhi is a unique strain of bacteria that greatly effects humans. So much so that despite many not understanding what it is, most have at least heard of Salmonella. This bacteria lives in the gut and is largely responsible for Typhiod fever, it has caused death in some and yet, many are carriers for the bacteria without even knowing it.

Typhoid fever was for a long time thought to be a disease that only affected poor communities. That is because though it may be easy to forget, hygiene, and the sanitation system of our sewers is not something many have access to. Without proper hygiene, bacteria such as Salmonella typhi are able to wreak havoc on a population. Although the frequency of Salmonella outbreaks has greatly decreased in developed countries, the threat still remains. According to the Centers for Disease Control and Prevention “An estimated 5,700 cases [of Typhoid Fever] occur each year in the United States.  Most cases (up to 75%) are acquired while traveling internationally. Typhoid fever is still common in the developing world, where it affects about 21.5 million people each year.” ¹

 

 

 

Check back each week to dive into the life, the history, the cure, and plenty of interesting instances of Salmonilla typhi.

 

 

 

 

 

1. Centers for Disease Control and Prevention . July 18, 2016.
   National Center for Emerging and Zoonotic Infectious Diseases (NCEZID)
   Division of Foodborne, Waterborne, and Environmental Diseases (DFWED)
2. Complete genome sequence of a multiple drug resistant Salmonella enterica serovar Typhi CT18
   Parkhill, J; Dougan, G; James, K D; Thomson, N R; et al.Nature; London413.6858 (Oct 25, 2001): 848-52
3. Photo: SUNDAY , 24 SEPTEMBER 2017. https://www.jokeblogger.com/hottopic/Salmonella. Pg. 5

A deeper look at Clostridium Botulinum

Many people have heard of Botulism but not many have heard of the bacteria behind it.  Clostridium Botulinum is the bacteria that releases the neurotoxin that causes Botulism.  Botulism trends have been connected with improperly prepared food, especially canned foods.  I don’t know about you guys but I LOVE homemade salsa and can’t imagine giving up my mom’s famous canned peaches! Today we’re going to take a deeper look into how botulism affects what we eat and how we get sick.

Due to the fact that C. botulinum do not need oxygen to survive, in fact they thrive in low oxygen conditions, means they can be hard to get rid of.  When the conditions for the bacteria are looking rough, they produce a protective spore that coats the key parts of the bacterium and has layers of protective membranes (Shapiro R.).  The neurtoxin is most commonly produced when food is improperly processed or canned in the kitchen. However, according to the USDA website, C. botulinum cannot grow below a pH of 4.6, so acidic foods, such as most fruits, tomatoes, and pickles, can be safely processed in a water bath canner.  Unfortunately foods with a higher pH need to be canned using a pressure cooker to ensure that the temperature reaches high enough to cause the C. botulinum spores to die (USDA website).

Botulism itself is a paralyzing disease that produces skeletal muscle paralysis by producing a presynaptic blockade to the release of acetylcholine (Cherington).

The mortality rate of botulism is fairly low especially if supportive care and trivalent equine antitoxin (to be discussed in further blogs) is administered early.  Botulism outbreaks, though rare are a public health emergency that require rapid recognition to prevent additional cases (Shapiro).

I’m excited to travel along this path of learning more about this hazardous bacteria with you.  Knowing how to properly can your peaches might just save your life, but perhaps Clostridium Botulinum will be the next biological weapon used in future wars? In any case, it pays to learn more!

Cherington, M. (1998, December 07). Clinical spectrum of botulism. Retrieved September 24, 2017.

Shapiro, R. L., Hatheway, C., & Swerdlow, D. L. (1998, August 01). Botulism in the United States: A Clinical and Epidemiologic Review. Retrieved September 24, 2017.

Mycobacterium tuberculosis

  Mycobacterium tuberculosis is the causative agent of tuberculosis, spreads worldwide as one of the most successful obligate bacterial pathogen and is still continues to kill million of people every year. Human acts as the only reservoir of this bacteria. They are highly aerobic bacteria and easily transmitted through coughing , sneezing and speaking around the person who is infected with M.tuberculosis.

Image: M.tuberculosis colonies. Source: CDC/ Dr. George Kubica

 

Epithelial cell are the dominant cell type in the lungs. M.tuberculosis target alveolar macrophage in the lower airways to establish infection[1]. This means that epithelial cell are the first point for the M.tuberculosis to be contacted in the human host. Once the host develop the M.tuberculosis then it is very difficult to view them under compound microscope. Extensive chemical research have shown M.tuberculosis consisting of three component. Out of them the outer layer is composed of mycolic acid which provide mycobacteria with remarkable impermeability to external service. This make it hard to view the with gram staining as they’ll appear both gram positive and gram negative[2].

….To be continued in next week.

 

 

Reference

1. Reuschl, A. et al, 2017. “Innate activation of human primary epithelial cells broadens the host response to M. bacterium in the airways. PLOS Pathogens 13(9).
2. Martinez A, Torello S, Kolter R, 1999. Sliding motility in mycobacteria. Journal of bacteriology 181(23):731-8. [PubMed]

A Sinister Bacteria: Vibrio Cholerae

  An internationally-known disease is usually not a good concept when it comes to world-wide health centers; often because the terrible, lethal illness it brings. What could be the reason behind such a calamity? It’s simple, a mean little bacteria called Vibrio cholerae. According to the CDC (Centers for Disease Control and Prevention), Cholera, caused by the bacteria V. cholerae, is rare in the United States and other industrialized nations. However, globally, cholera cases have increased steadily since 2005 and the disease still occurs in many places including Africa, Southeast Asia, and Haiti.

  Looking a little deeper into this, infection due to V. cholerae begins with the ingestion of contaminated water or food. After passage through the acid barrier of the stomach, the organism colonizes the epithelium of the small intestine by means of the toxin-coregulated pili (Taylor et al., 1987). Toxin is then produced by V. cholerae and secreted into the surrounding intestinal epithelial tissue, where it disrupts ion transport. Severe diarrhea and vomiting follow, where the infected person experiences a catastrophic loss of water and electrolytes. 

https://microbewiki.kenyon.edu/index.php/Cholera

Figure 1. V. Cholerae seen with its single, sheathed, polar flagellum.

Glancing at the bacteria itself: V. cholerae, a member of the family Vibrionaceae, is a facultatively anaero-bic, Gram-negative, non-spore-forming curved rod, about 1.4–2.6mm long, capable of respiratory and fermentative metabolism; it is well defined on the basis of biochemical tests and DNA homology studies (Baumann, Furniss & Lee, 1984). Seen in the figure above, V. cholerae has a means of motility via flagellum.

 

• HAYDEN SWARTZ 9/22/17

 

 

 

Bibilography

Baumann P, Furniss AL, Lee JV (1984). Genus 1, Vibrio. In: Krieg PNR, Halt JG, eds. Bergey’s manual of systematic bacteriology. Vol. 1. Baltimore, Williams & Wilkins: 518–538.

Taylor RK et al. (1987). Use of phoA gene fusions to identify a pilus coloniza- tion factor co-ordinately regulated with cholera toxin. Proceedings of the National Academy of Sciences, 84:2833–2837.

First Incidences of Chikungunya Virus

Chikungunya Virus is a viral disease that is transmitted by a mosquito. Its transmission by a mosquito is the reason why I was not surprised when Robinson et al. first described its epidemic in Tanzania in 1955. Other African countries such as Mozambique, Angola, Botswana to name but a few also encountered this infection through antibody analysis of human sera (uncoagulated part of human blood). Symptoms of the disease are join (ankles, elbows, wrist etc.) pain and stiffness. Chikungunya means” he who walks bents up” in Swahili. Due to its severe pain, patients with this infection can’t walk without bending. Brighton et al. had 107 cases investigated which were divided into 4 groups based on the result of their symptoms. The study was intended to investigate the nature of residual symptoms in these patients after encountering the symptoms three years ago. Their result showed that 94 patients had no residual symptoms, 4 patients had mild discomfort, and 3 patients had persistent stiffness without feeling any pain while 6 patients had persistent pain and stiffness [1]. Since up to date, there is no vaccine or medicine to treat this infection, it is important to see your healthcare provider to help you recover from this infection [2]. This is particularly evident from the study as those who seek for doctor’s help had their symptoms eliminated [1]. This was the initial report on this virus. However, so many studies were done on this virus and they found interesting things about it such as other clinical symptoms, preventive measures as well as its association with other diseases like hepatitis, meningitis etc. [3] which I would expand on in my next blog post.

[1] Brighton, S. W., O. W. Prozesky, and A. L. De La Harpe. “Chikungunya virus infection-A retrospective study of 107 cases.” South African Medical Journal68.9 (1983): 313-315.

[2] https://www.cdc.gov/chikungunya/symptoms/index.html

[3] Economopoulou, A., et al. “Atypical Chikungunya virus infections: clinical manifestations, mortality and risk factors for severe disease during the 2005–2006 outbreak on Reunion.” Epidemiology & Infection 137.4 (2009): 534-541.