The End

It's the end of of a long but fruitful semester Unfortunately, I probably won't be posting any longer. I hope this blog shared some useful information. It was fun reading about all the current (and not so current) events and research taking place right now. Soon I hope to use this knowledge to help others get well and prevent the spread of infectious diseases. For now, thanks for reading and goodbye!

Using Viruses Against Resistant Bacteria

   by  AJC1 

Bacteriophages (phages for short) are viruses that infect bacteria, usually only a certain species or strain. In the 1920s and 1930s phages were used to combat bacterial infections before the widespread use of antibiotics. The introduction of antibiotics pushed phage therapy out of use because phages were difficult to study and manipulate and antibiotics were easier to administer and could cure numerous infections. Phage therapy is still being used in some countries in the Baltic and Eastern Europe. Modern medicine has seen vast improvements in molecular biology, genetics, and biochemistry that could make bacteriophages the successor to antibiotics and a cure for antibiotic-resistant infections.

Bacteriophages are highly specific and can be modified to only infect a pathogenic microbe. Phages by nature only attack bacteria and can be safely administered to other organisms, including humans and livestock, with very little risk. There are no side effects and the body naturally eliminates the phages.  Antibiotics are chemicals designed to damage and destroy bacteria unrestrained, whether or not the affected microbes are virulent or normal body flora. The destruction of beneficial bacteria can lead to further infections by opportunistic pathogenic bacteria and could upset homeostasis. Phages are specifically modified to target a single microbe and can be selected to only attack one strain, so virulent forms of common beneficial bacteria can be eliminated without killing normal body flora.

Bacteriophages are better on-site antimicrobial agent compared to oral or injected antibiotics. Chemicals released into the body are absorbed, spread, and eliminated. The site of an infection (inflamed wound, lymph nodes, organ, etc.) might only get a diluted compound that may not be effective. One of the reasons antibiotics are prescribed for several days to weeks is to build up a concentration that is lethal to the pathogens. Missing a dose could lower the concentration in the body and allow resistant bacteria to survive.  Parts of the body that have nothing to do with the infection also get a lethal dose and normal bacteria die. A bacteriophage grows in the target bacteria, so it concentrates where the target is concentrated. The infected area quickly becomes saturated with the virus as it infects bacteria, multiplies, lyses the cell, and attacks other targets nearby. It is an exponential growth of the virus where it is needed most, and causes the pathogen numbers to exponentially decrease. The virus is not active where targets are not present and does no harm except to the specific species or strain for which it is designed for.

Bacteriophages can be modified to enhance their specificity and prolong their effectiveness. Genetic engineering and molecular biology have made it possible to alter viruses to make them more potent and more specific. A virus or family of viruses could be altered several times to attack bacterial species within the same genus. The benefits are “custom” treatments that will target only the microbes that are causing a disease.  Bacteria can eventually develop some immunity to a virus. 

To make treatments effective, it is usually necessary to combine several viruses into a cocktail that targets one to several species in several different ways. It makes it harder for bacteria to react and become resistant, and even kills already resistant strains because multiple different phages are present. Over time, it will probably be necessary to modify the virus as bacteria start to cope with it, and in some instances phase out phages that are ineffective. However, it is not known how many times a virus can be altered, and there are hundreds of bacteriophages to use. Once the knowledge and technology are established, it would be very easy and relatively inexpensive to quickly change the cocktail, and it could be changed many, many times.

A few problems with phages are present right now. The technology and research are not at a commercial state yet, so engineering viruses is still expensive. The viruses need to be in a cocktail of several types and an adjunct to make sure the virus stays in the body long enough to kill all the target cells. The easiest and least expensive way to culture large amounts of virus now is to grow host bacteria and let the virus replicate in the host. Certain highly specific bacteriophages to highly virulent species have to be grown in the cell, which means facilities growing large quantities of dangerous organisms. Phages are made primarily from proteins, so there is a risk that it will be viewed as an antigen and could illicit an immune response such as an allergic reaction. But there is another benefit viruses can have without actually using live phages.

Bacteriophages produce a class of enzymes called lysins that digest the cell wall of bacteria and kill the cell.  Lysins are used by the virus the break down the cell wall prior to bursting the cell and releasing copies. They can lyse cells from the outside as well, even when phages are not present.  The enzymes have been isolated and research is being done to find uses for it. Lysins could be administered just like antibiotics, but they are more specific. Some lysins will only kill one species of bacteria but will not harm other species from the same genus. There are many lysins already available, and there is no indication that bacteria can build a resistance to it.

Phage Renaissance 

Antimicrobial Nanoparticles and MRSA

   by  EMSL "Zinc Oxide Particles"

A study done last year shows that certain nanoparticles can kill bacteria, even MRSA and other resistant strains. The nanoparticles are made with zinc oxide (ZnO) and titanium dioxide (TiO2). The researchers believe one of the ways these resistant species are so hard to control is their ability to form biofilms. Biofilms are large aggregates of bacteria that produce a matrix. The matrix protects some of the bacteria by not allowing antibiotics to come in to contact with the bacterial cells. The study focuses on the effectiveness of nanoparticles on the bacterial biofilms of MRSA.

Several isolates of MRSA that were shown to produce biofilms were cultured and allowed to aggregate. Commercially produced TiO2 and ZnO nanoparticles were introduced and the effects were measured. The particles had much greater inhibitory effects than all the antibiotics tested with it. Even low doses were better than most antibiotics, and some doses even prevented biofilms from forming. The results show that nanoparticles can be valuable tools to combat resistant bacterial strains. Using the particles to coat medical devices where biofilms readily form, like catheters, may prevent the formation of biofilms. Other possibilities for drugs or use with antibiotics should be researched further.

Antimicrobial Activity of Zinc and Titanium Nanoparticles against Biofilm Producing MRSA

Ants and Disease Transmission

   by  tarotastic 

Entomology and Biology professor David Hughes from Penn State was given the lead to find out if ants can teach us about the spread of disease in certain environments, such as large communal groups and offices. The National Science Foundation and the National Institutes of Health granted Dr. Hughes and his team a $1.8 million grant under the Ecology and Evolution of Infectious Diseases research initiative. The initiative "supports efforts to understand the underlying ecological and biological mechanisms that govern relationships between human-induced environmental changes and the emergence and transmission of infectious diseases."

The researchers will introduce various agents to ants and track the transmission. By varying the colony size and complexity, they hope to produce a mathematical model to expain the spread of diseases in populations that can eventually be used to predict transmission routes of human pathogens and help manage outbreaks. The team believes that ants can provide a reliable interactive community which to base the model on. Ants can be manipulated and colony size and structure can easily be changed to fit the goals of the researchers, and they're behavior is similar to other social groups.

A positive side effect of the study is an in-depth look at ant colony interactions. The social structures and methods of carrying out tasks could lead to a better understanding of how colonies react to insecticides that could be used to create more effective means of controlling pest ant species. The mathematical model of transmission could also be applied to livestock and agricultural diseases, leading to better prevention strategies and healthier animals and crops.

Penn State Study
Ecology and Evolution of Infectious Diseases Initiative

Infections From Cats

This weekend some friends finally got me to watch the BBC show "Sherlock". I know it's in its 3rd season, but I'm usually behind on things like this. Anyways, I've made my way through the 1st season, and its pretty good, even if some of the lab tests he performs are wrong or impossible, but that's another topic. In the 3rd (or last) episode, a woman dies from what seems to be an infection, but they are unable to figure out how she was infected. Watson visits her home and believes it was cat scratch. I'm not going to give away any more, but this got me thinking about cats. My family has had our share of cats, and along with that cat scratches. So what are some things you can get from your overly playful cat?

Cat scratch fever (Bartonellosis) is a bacterial infection caused by Bartonella henselae. It is the most common bacterial disease acquired from cats. The bacteria are commonly found in cats and don't usually cause a disease until it enters into the bloodstream. Fleas can also transmit the bacteria. Kittens are the most prone to harboring the bacteria and causing an infection in people or spreading it to other cats. Cats can also carry Salmonella and can infect through a scratch.

Cats may also have dirt in the claws, which can have a lot of bacteria found in soil that are pathogenic. The genus Clostridium lives in the soil and can cause tetanus and botulism. Bacillus can cause serious infections, including anthrax. Listeria and Camplybactor may be found and can also be transmitted via cat scratches.

This is not a comprehensive list, but just some common infections that can be passed from cats to humans.

Cornell Veterinary College
Soil-Related Bacterial Infections

UPDATE: Chikungunya Virus

Over the last week four more cases of Chikungunya virus have been reported in Alabama, along with the Huntsville case last week. One of those cases was in Birmingham. So far, all the people infected were travelers to parts of the Caribbean and no cases of infection from Alabama mosquitoes have been reported. However, the disease can cause relatively mild symptoms that may seem like allergies and a bad week of arthritis, which may prompt some people to stay at home instead of going to the doctor, so the exact number of actual cases is unknown.

There is still worry that the virus will spread to mosquitoes in the Southeast and an outbreak will occur. The CDC recommends following mosquito bite prevention guidelines, which can be found on their website and in the previous post. The CDC also urges anyone who has a fever and joint pain to see a doctor. There is no treatment and symptoms go away in about a week, but it is important that clinicians correctly identify cases of the virus so the infection patterns and numbers can be used to gather information and monitor its spread.

Certain Caribbean regions have been assigned Precaution Level 1 because of Chikungunya virus outbreaks. Anyone traveling to the Caribbean or South America should look up the region on the CDC Traveler's Page, which has information on current outbreaks and how to best prepare for travel to those regions.

CDC Mosquito Bite Prevention Guidelines

• Use air conditioning or window/door screens to keep mosquitoes outside. If you are not able to protect yourself from mosquitoes inside your home or hotel, sleep under a mosquito bed net.
• Help reduce the number of mosquitoes outside your home or hotel room by emptying standing water from containers such as flowerpots or buckets.
• When weather permits, wear long-sleeved shirts and long pants.
• Use insect repellents.
• Repellents containing DEET, picaridin, IR3535, and oil of lemon eucalyptus and para-menthane-diol products provide long lasting protection.
• If you use both sunscreen and insect repellent, apply the sunscreen first and then the repellent. 
• Do not spray repellent on the skin under your clothing.
• Treat clothing with permethrin or purchase permethrin-treated clothing.
• Always follow the label instructions when using insect repellent or sunscreen.

AL.com 4 More Virus Cases
CDC Chikungunya Virus
CDC Traveler's Page

Chikungunya Virus in the Southeast

The virus is transmitted by the yellow fever mosquito, which also carries yellow fever and dengue fever. The virus can cause fever and joint pain that can be debilitating in severe cases. The virus cannot be transmitted between people, but only by mosquito bite. There is no vaccine against it. Chikungunya outbreaks have been reported in several Central American and Caribbean countries in the past two years. So far, all the reported cases in the U.S. have been by travelers to countries where the virus is established.

The virus can spread by a mosquito biting someone infected and then biting someone without the disease. The CDC is worried that the virus will spread to the United States from either infected mosquitoes from Caribbean countries or from infected individuals introducing the virus into the yellow fever mosquitoes already found in the United States, and possibly other mosquito species.

Symptoms develop within 3 to 7 days of infection. The fever usually lasts a few days to a week, but the joint pain may last more than a month. Anyone with a fever, headache, rash, and/or joint pain should go to a doctor.

The CDC gives guidelines to prevent mosquito bites and possible infection.

• Use air conditioning or window/door screens to keep mosquitoes outside. If you are not able to protect yourself from mosquitoes inside your home or hotel, sleep under a mosquito bed net.
• Help reduce the number of mosquitoes outside your home or hotel room by emptying standing water from containers such as flowerpots or buckets.
• When weather permits, wear long-sleeved shirts and long pants.
• Use insect repellents.
• Repellents containing DEET, picaridin, IR3535, and oil of lemon eucalyptus and para-menthane-diol products provide long lasting protection.
• If you use both sunscreen and insect repellent, apply the sunscreen first and then the repellent. 
• Do not spray repellent on the skin under your clothing.
• Treat clothing with permethrin or purchase permethrin-treated clothing.
• Always follow the label instructions when using insect repellent or sunscreen.

CDC Chikungunya virus
 AL.com First Alabama Virus Case