All posts by kdshives

Necrotizing fasciitis in the news

Necrotizing fasciitis. For many people this is one of the most terrifying, invasive infections imaginable, and for one unlucky woman in Georgia this is her current reality. Reports of this disease date back to Hippocrates in 500 BC, whose early description was that “diffused erysipelas caused by trivial accidents, [where] flesh, sinews, and bones fell away in large quantities, [leading to] death in many cases1.” Many people regard the disease as a medical monster, an invasive and lethal infection that progresses at a rate straight out of science fiction.

Photomicrograph of Streptococcus pyogenes bact...
Photomicrograph of Streptococcus pyogenes bacteria, 900x Mag. A pus specimen, viewed using Pappenheim’s stain. (Photo credit: Wikipedia)

For those of you not familiar with the story, a young Masters student named Aimee Copeland was injured while on a home-made zipline. When the line broke she fell and cut her leg on rocks in the river beneath her. What started as a small cut on her leg quickly grew into a life threatening infection that resulted in the amputation of her entire left leg and possibly her hands in order to limit the spread of the disease. How is it possible that a small injury so quickly became life threatening? To understand this we have to understand more about necrotizing fasciitis itself and the bacteria that cause it.

Continue reading Necrotizing fasciitis in the news

Ask A Microbiologist #1

Work. (1 of 2)
Work. (1 of 2) (Photo credit: musicalwds)

After writing for a month I’ve gotten my first reader question and I’m excited to share the answer with the rest of you. Here’s the question I got a week ago from a reader working in a tissue bank regarding their samples:

I work in a tissue bank and have some concerns in the practice we use for handling our tissue. When the tissue is ready for processing we receive it in a partially frozen state. To thaw, we have the tissue soak in sterile water for a period of 15 min. We process in rooms with air exchanges that are similar to a hospitals OR. We do have preventative measures after the process we take to protect the tissue. However, we recently have been trying to accommodate clients by processing aseptically. My question is, can the use of water create a harbor for bacterial growth considering the length of time the tissue will remain in the room throughout the duration of the process. (8 to 16 hours) and would there be any alternative means of a safer way in which to thaw the tissue?                                                                                                                -G

 This is a great question but a little bit outside of lab work that I’m personally familiar with. Thankfully though, aseptic technique works the same way everywhere, so here are some suggestions I came up with based on my experience. Continue reading Ask A Microbiologist #1

The Clap is Back!

Sexually transmitted disease
Sexually transmitted disease (Photo credit: Wikipedia)

With the presence of non-curable viral sexually transmitted disease (herpesvirus and HIV) at the forefront of public fear and awareness it is very easy to think of the bacterially induced STD’s as curable and less dangerous. However, one of the key challenges faced by the medical community today is the rapidly rising rates of antibiotic resistance in bacteria as diverse as M. tuberculosis to E. coli. This rising tide of antibiotic resistance is not restricted to certain species and has been more recently documented in Neisseria gonorrhoeae, the causative agent of gonorrhea, also colloquially known as “the clap.” Continue reading The Clap is Back!

Novel vaccines for an old disease

bananas
bananas (Photo credit: Fernando Stankuns)

In order to eradicate polio there must be a vaccine in use that is affordable, stable for delivery to undeveloped regions, safe for infants, and not result in the circulation of virus that can revert to a disease causing phenotype (see The Problem with Polio). One method creating this vaccine that could theoretically work is the introduction of recombinant polio capsid proteins being expressed in food items such as bananas instead of in a traditional vaccine1. For example, it may be possible to engineer bananas that express recombinant polio capsid proteins in such a way that antigenic epitopes of the three serotypes of polio are expressed and illicit an immune response at the gut mucosal level when ingested. These recombinant proteins could be engineered so that they are expressed at conserved levels in the banana and are heat-stable. This would facilitate the transport of the bananas, or even food products made with the antigenic bananas, to rural areas in hot climates where the virus is still endemic. Immunity could be built up in the individual by repeated ingestion of the engineered bananas, and subtyped bananas (serotype 1 antigen expressing, bivalent 1 and 2, etc) could be made for specific regions with only certain strains of the virus circulating. Another benefit would be that infants can ingest bananas and would be a much easier and safer route of inoculation than injection. This food-based vaccine may also be more well-accepted by communities distrustful of injections being given by unknown aid workers. This is very important because sensitivity and reassurance are very important in not alienating the very people that we are trying to help with vaccine campaigns. This approach using modified bananas would also result in a cheap and effective means to generate many doses of the vaccine that could potentially lower the price per dose of polio vaccination.

If this banana-based vaccine were developed it would be a great step forward in the fight against polio. Large amounts of bananas could be grown and given to children in areas with circulating polio that would result in significant herd immunity without concomitant circulation of vaccine virus. This would limit persistent shedding of virus and destruction of the only known reservoir for polio. Using this method it would be possible to follow the current WHO protocols for vaccination and National Immunization Days, certification of polio-free regions, and the eventual discontinuation of vaccination three years after WHO certification. However, much work must still be done before these modified foods are a reality and much will have to be done in order to convince the general public of the safety and efficacy of these genetically modified organisms.

 

1.        Goldstein, D.A. & Thomas, J.A. Biopharmaceuticals derived from genetically modified plants. QJM : monthly journal of the Association of Physicians 97, 705-16 (2004).

How do viruses move outside the cell?

In line with the recent article “Are viruses alive?” I would like to further explore the general nature of viruses. One question that I was recently asked was “does a virus move?” Being that viruses are not technically alive in the sense that we know it they also cannot move in a self-directed manner. This is in stark comparison to some other microbes such as Schistosoma cercariae, a parasitic worm, which is capable of burrowing through intact human skin and gaining access to the vascular system within 5 minutes (1). Thankfully viruses cannot do this, much to our benefit. Because of their very nature viruses cannot mechanically move in a self-directed manner and are subject to movement solely based upon environmental interactions. Essentially, they are not only hijackers who take over cellular processes for their own good, but environmental hitchhikers as well. Continue reading How do viruses move outside the cell?

The Importance of the Human Element: A review of The Immortal Life of Henrietta Lacks

Cover of "The Immortal Life of Henrietta ...As a young woman working in microbiology I often think about HPV (human papillomavirus) and its impact on women. Thanks to decades of research we have discovered that HPV is a causative agent of cervical cancer (and other cancers, but that’s another article). Even more impressive is that there is now a vaccine designed to protect against the types that most commonly cause cancer, serotypes 16 and 18. This is great news for a generation of young women who will not have to know the torture of cervical cancer and losing their ability to bear children that their mothers and grandmothers faced. Even my own family has been touched by this disease and I am very thankful that, thanks to modern diagnostics and surgery, my loved one is still here with me. Incredibly, all of these advances can be tracked to one woman who unwittingly changed the face of medicine: Henrietta Lacks, or HeLa, as she is now known.

Read on to find out more about this woman and the fascinating book that has been written about her impact on modern science. Continue reading The Importance of the Human Element: A review of The Immortal Life of Henrietta Lacks