Transfusion Reactions

This week in lab we combined elements of two of the classes we are taking this semester: Blood Bank and Infectious Disease.  I felt that the exercise also brought together several things we have learned since beginning the program.  We processed simulated samples from patients that were experiencing a transfusion reaction.  These reactions can occur for several reasons including factors with the recipient’s immune system and contamination of the blood product itself. 

The process of determining what could be responsible for a transfusion reaction began with reviewing the patient’s vital signs and symptoms, looking for clerical errors, processing several laboratory tests on the individual’s blood and urine, and finally setting up microbiological testing  from the donor material to see if a microbial organism was growing in the product itself.



The blood product that was being transfused in our case was a unit of platelets, which have the highest rate of contamination since they are incubated at room temperature up to five days.

The first step to analyzing the microbiological aspect of the laboratory was utilizing a Gram Stain to get an idea whether any organisms were present and a preliminary identification of those that were observed. The appropriate media for growth of the specimen included Sheep Blood Agar, MacConkey, Chocolate, and a time saving special plate that differentiates organisms by causing colonies of various species to appear specific colors thus saving time in the determination of the causative microbe.

When observing the Gram Stain of my specimen I noticed many Gram positive organisms with elongated protrusions growing out of their sides, which are known as germ tubes.  This led me to believe that the specimen had become contaminated by a Candida species yeast organism.  After 24 hours, I was able to observe the different media plates that were set up and determine that it was the Candida albicans species, based off its color on the specialty media that differentiated organisms of the Candida genus by the color of the colony growth.

As I stated before, I thought this laboratory exercise brought together several aspects of the program we have learned about so far, and was a good simulation of a real world circumstance.

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.