Acanthamoeba, and you can too!

Although we have not covered material on parasites yet in our class, I wanted to talk a little this week about the significance of Acanthamoeba species, a protozoan genus that can commonly cause several different complications affecting different parts of the body.

Acanthamoeba species can be found in the soil and freshwater environments in many places around the world, and typically feed on bacteria which also reside in these environments.  However, some opportunistic species can become a health risk to people.  Depending on the site or method of entry into the body, this can result in keratitis and encephalitis/meningitis.  Amoeboid Keratitis occurs when the amoeba comes into contact with the eye, and can lead to blindness in severe cases; in many cases this results from improper use of tap water to clean contact lenses.  Acanthamoeba granulomatous encephalitis occurs when the amoeba enters the nasal mucus membrane and migrates to the brain to feed.  Although very rare, this type of infection usually results in death.¹

Since these organisms can encyst, they are extremely difficult for the host’s immune system to rid itself, and many drugs are ineffective as well.

Acanthamoeba species are also carriers for many pathogenically significant bacteria and virus species, and therefore may operate as a vector for infection for these pathogens which include Legionella species, Staphylococcus aureus, and Campylobacter species.¹ 

So remember, never use tap water to clean your contacts or flush out your sinuses!

Reference

1.      Wikipedia contributors. "Acanthamoeba." Wikipedia, The Free Encyclopedia. Wikipedia, The Free Encyclopedia, 11 Jun. 2014. Web. 20 Jun. 2014.

Monitoring Sepsis through the Detection of latent Viruses

The topic of my entry this week will combine the subject matter of two previous posts: septic infections and viruses.

 It may sound strange, but some study has been done that suggests that it may be possible to monitor progression/severity of septic infections through the detection of previously latent viruses, indicating a clinically significant depressed immune system.  In order to accomplish this, several serially collected blood and/or plasma samples were obtained from hospitalized patients over a period of time and monitored for an increase in viral DNA from species that are capable of becoming latent, or hiding within the host’s DNA.  Examples of these which were used in the study included cytomegalovirus (CMV), Epstein-Barr (EBV), and herpes-simplex (HSV).¹

In theory, when the immune system is suppressed to a certain extent, these latent viruses would be reactivated and enter the patient’s blood.  For the purpose of this study, an increase in the viral DNA present in the patient’s blood was cross correlated to secondary infections such as bacteria and fungi to see if a relationship could be established, which could be used to indicate the underlying status of the corresponding person’s immune system.¹

It was determined that this method of serially monitoring the amount of virus present in a septic patient’s blood could be useful in determining the severity of the depression of the immune system.  The authors suggest that this could be best accomplished through monitoring a panel of common viruses such as CMV, EBV, HSV as well as others, and observed for a marked increase across the board which could indicate that an individual has entered the immunosuppressive stage of sepsis meaning that they would be almost incapable of fighting off infections from various opportunistic pathogens such as bacteria and fungi.¹

If you would like to read the full article and see the figures, here is the link:

http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0098819

Reference:

1.      Walton AH, Muenzer JT, Rasche D, Boomer JS, Sato B, et al. (2014) Reactivation of Multiple Viruses in Patients with Sepsis. PLoS ONE 9(6): e98819. doi:10.1371/journal.pone.0098819

"So what is a virus?"

Over the past week we have been learning about viruses in our lecture portion of the course.  We discussed their overall morphology and biochemical components, as well as laboratory diagnosis methods for a wide variety of clinically significant viruses.  With this week’s post, I wanted to briefly cover some of this information.

So you may ask:

“So what is a virus?”

“How do they infect us?”

“What kind of treatment can I receive for an infection?”

These are just some of the commonly asked questions about viruses.  Primarily, they are composed of a little protein and one type of genetic material; unlike other organisms which have both RNA and DNA.  This genetic material can be either single strand DNA, double stranded DNA, single strand RNA, or double stranded RNA and is one method of categorization.  Viruses, believe it or not, are considered by some scientist to not even really be alive, since they are incapable of reproducing/replicating without high jacking the cellular components of a host. 

Since there is such a wide array of virus types, there likewise are widely variable methods of infection that are utilized by these pathogens.  This can range from respiratory, skin to skin, body fluids, and even in some cases vectors such as mosquitoes.  Once inside the body, viruses look for specific chemical markers on cells that they have specialized to utilize for their replication.

Especially with viruses, the old proverb “An ounce of prevention is better than a pound of cure” is applicable.  The most effective method to prevent the majority of clinically significant viruses is vaccination, because some treatment methods are not effective against them.  Antibiotics work only on cellular pathogens, and are therefore useless.  For some viruses, there are anti-viral medications that can be helpful, but these are usually only developed for more severe diseases such as HIV, Hepatitis C, and influenza; not for every virus.  In many cases, symptoms are treated, and the individual’s immune system will eventually rid itself of the virus.

Diagnosis can be made through several ways, which are best classified as either direct or indirect.  Direct methods look for the virus itself by detecting proteins or genetic material, while indirect look for antibodies developed by the immune system which are specific to antigens of the virus in question.

 

Legionnaire’s Disease

As many of you may have heard, recently there have been several cases of Legionnaire’s Disease diagnosed at UAB Hospital in Downtown Birmingham, Alabama.  I thought that for this week’s topic, I would give some background information about this condition and the causative pathogen for this disease.

Legionnaire’s Disease is a type of pneumonia brought about by an infection of a bacterium from the Legionella genus.  These organisms can be found in virtually any source of water, and are likewise transferred through inhalation of water droplets that contain the pathogen, not person to person.  The disease has an incubation time of two to ten days and is characterized by symptoms that are similar to other types of bacterial pneumonia which may include fever, headache, and nonproductive cough.  The individuals at the highest risk of infection for this disease include the elderly, smokers, and those who are immunocompromised, while those with a healthy immune system either fight off the bacteria and never get Legionnaire’s Disease or only get a milder case.¹

When you combine the facts, it is clear how an outbreak can easily happen in a hospital environment.  Many of the individuals have a weakened immune system, and if exposed to the Legionella bacterium in the water supply, they can easily contract this disease. 

Diagnosis of this disease is accomplished through a variety of means such as special fluorescent stains, DNA detection, and even a urine antigen test.  Since this organism is difficult to grow and isolate on standard media, special media must be utilized that can aid in its culture.¹

Hopefully this information helped in the understanding of this disease.

References:

1.      Tillie, Patricia M (2014). Legionella. Bailey and Scott’s Diagnostic Microbiology 13^th Edition (pp. 424-430). St. Louis, Missouri: Elsevier Mosby.

Bacteremia and Blood Culture Part 2

The presence an infection in the blood is detected through the use of blood cultures.  For this procedure, blood is collected into sterile bottles containing a media which when metabolized by any present organism will result in the release of carbon dioxide.  This alters the pH of the substrate on the bottom of the container, causing a change in color which is generally measured by a sensor in an automated incubator, usually monitored up to a five day span.  Once this color change is detected, the medical technologist will receive an alarm indicating which bottle has tested positive for an increase of carbon dioxide so that further culture and identification of the pathogen can occur.

In order to achieve this, blood from the culture bottle is inoculated onto media for isolation/identification of the organism as well as Gram stained so that a preliminary identification can occur and general treatment can begin.  After 24 hours the resulting growth on the media can be observed and processed using rapid testing such as oxidase or catalase to obtain a final identification.  If a final identification cannot be determined at this step, identification systems can be utilized to identify the pathogen.  Upon final identification, antibiotic susceptibility testing can be initiated in order to provide a more precise antibiotic treatment that can be used to rid the patient of the infection.

This is a brief description of the lecture information and laboratory exercise we performed during the first week of our course.  I processed a blood culture bottle by using this method of isolation culture, rapid testing, and identification systems, and was able to determine that the patient in question had bacteremia resulting from Escherichia coli.  I found this exercise to be quite informative, and hopefully my description can aid in the understanding of how this process works in a medical laboratory setting.

Bacteremia and Blood Culture Part 1

For my first official entries, I thought it would be good to review over some of the information and activities we have covered so far in the course during the first couple of weeks, particularly bacteremia and blood cultures.  This will be a two part post, with the second half being posted next week.

Under normal circumstances and in healthy individuals, the blood system within your body should not contain organisms of any kind, and is considered to be a sterile body fluid.  Inevitably, due to incidences such as cuts, IV catheters, and infections of other body sites, pathogens such as bacteria or viruses can gain access into the blood stream.  The immune system is able to normally rid itself of these invasions in most healthy adults.  Unfortunately for individuals with a weak or compromised immune system, this can lead to a more serious complication.  Since the blood system is basically a highway throughout the body, if undiagnosed or untreated this can lead to systemic infections that can affect various organs and may lead to death. 

The terminology used to describe these conditions is based on the responsible organism and the severity of the infection.  Some of these include bacteremia, viremia, and fungemia which indicate the presence of bacteria, viruses, and fungi in the blood, respectively.  Septicemia is another term that is used to indicate that pathogens are present and reproducing within the blood stream. 

Welcome

Welcome to Infection of Knowledge!  This blog was created for the purpose of giving an inside view to the world of the Microbiology/Infectious Disease scientific discipline from the perspective of a graduate student throughout the course of an entire semester.  The subject matter posted here will cover various issues ranging from current events related to the field to interesting topics or information discussed in some of the coursework and laboratory exercises that I am currently undertaking. Hopefully, this information can help others to better understand the biological medical laboratory, and shed light on some of the lesser known facts related to this area of expertise.