A Way Our of Our Antibiotic Crisis

August 28, 2015 by

July 24, 2015

By Medical Discovery News

A petri dish

Antibiotic resistance occurs when strains of bacteria that infect people – such as staph, tuberculosis, and gonorrhea – do not respond to antibiotic treatments. In America, 2 million people become infected with resistant bacteria every year and at least 23,000 die each year because of those infections. If nothing is done to stop or slow the resistance of bacteria to antibiotics, the World Health Organization (WHO) warns that we will find ourselves in a post-antibiotic world, in which minor injuries and common infections will be life-threatening once again.

The crisis arose primarily from three conditions. First, when people are given a weeks’ worth of antibiotics and stop taking them as soon as symptoms improve, they often expose the bacteria causing their infection to the medicine without killing it. This allows the bacteria to quickly mutate to further avoid the effects of the antibiotic. Second, antibiotics are over-prescribed. Most common illnesses like the cold, flu, sore throat, bronchitis, and ear infection are caused by viruses, not bacteria, so antibiotics are essentially useless against them. Yet they are prescribed 60-70 percent of the time for these infections. This once again provides bacteria in the body unnecessary contact with antibiotics. Third, tons of antibiotics are used every year in the agriculture industry. They are fed to livestock on a regular basis with feed to promote growth and theoretically for good health. But animals are also prone to bacterial infections, and now, to antibiotic-resistant bacteria, which spreads to humans who eat their meat or who eat crops that have been fertilized by the livestock. The good news is that the Food and Drug Administration (FDA) is working to focus antibiotic use on bacterial infections and regulate its use in livestock.

An easy solution to this problem might be to create new antibiotics, but it’s not that simple. It takes an average of 12 years and millions of dollars to research new antibiotics and make them available on the market, which is a huge investment considering they are normally only taken for up to 10 days. But there’s an even bigger challenge: microbiologists can only cultivate about 1 percent of all bacteria in the lab, including specimens that live in and on the human body. The ability to grow diverse bacteria is important because most antibiotics actually come from bacteria, produced as a defense against other microbes.

Slava Epstein, a professor of microbial ecology at Northeastern University, came up with an ingenious approach to solving this problem. He speculated that we are unable to grow these bacteria in the lab because we were not providing the essential nutrients they needed to grow. Working with soil bacteria, which are a huge source for developing antibiotics, he created the iChip. The iChip allows bacteria to grow directly in soil, which is their natural environment, while being monitored.

To date, about 24 potential antimicrobials have been identified from 50,000 bacteria that remain unable to grow in the lab. With possibly billions of bacteria left to grow and examine, the number of new drugs awaiting discovery is seemingly endless.

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Viruses Up to Bat

April 11, 2014 by

April 11, 2014

By Medical Discovery News

Bat

In tales, bats are feared because they could be blood-sucking vampires in disguise. Obviously, Dracula isn’t real, but science has recently uncovered a dark secret that bats have been keeping: viral reservoirs.

Reservoirs are bodies of collected water. Viral reservoirs are a collection of viruses carried by one species. Bats are an important source for a variety of viruses that can infect other animals and humans, such as deadly viruses SARS, Ebola, and MERS.

Bats are among the most abundant and diverse vertebrates on earth and are found on every continent except Antarctica. Their ability to maintain viruses may date back to ancient times. Viruses can cause persistent infections in bats or they can lay dormant. Since bats also have relatively long lifespans – up to 25 years – if they have a persistent virus they have a good chance of infecting others with it, especially since they can fly and travel long distances. Bats also live in close-knit communities, so they are likely to pass infections to other bats, thereby maintaining viruses in the population. Some viruses spread by direct contact, while others such as rabies can be spread by droplets of saliva, mucus, urine, or feces. 

While scientists have known for a while that bats are a source of the rabies virus, they have recently isolated almost 70 other viruses from bats. Most of these only infect fellow bats, not other animals or people, but they do carry some dangerous human pathogens like Japanese Encephalitis, Chikungunya, Rift Valley Fever, Nipah viruses, and Hendra viruses. 

Henipaviruses were first discovered as the cause of an outbreak of an acute respiratory illness in two humans and 22 horses in Hendra, a suburb of Brisbane, Australia, in 1994. The virus kills 75 percent of horses who are infected and 60 percent of people. That’s an especially deadly virus. Since then, there have been 39 Hendra outbreaks in horses, two of which spread to people. That virus was later found to be genetically related to another virus called the Nipah virus, which emerged in Malaysia in 1999. There have been nine more outbreaks of the Nipah virus since then, killing almost half of the people infected. Bats were probably responsible for many of these outbreaks.

In the latest study, 42 percent of the 2,000 Straw-coloured Fruit Bats from 12 African countries harbored Henipaviruses. About one-third of the bats also carried a rabies-like virus called Lagos bat virus. Since Henipaviruses can be easily transmitted, people living near bat populations could be at risk of infection.

Before mass bat hunts begin, it’s important to know that bats play essential roles in the ecosystem and cannot be eliminated without drastic consequences. Therefore people need to be cautious and vigilant about potential exposure to bat viruses. Ongoing research will hopefully create new antiviral vaccines that protect people. As humans continue to invade wildlife areas, so will the possibilities of contracting new viral infections. 

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Aging But Still Protected

June 14, 2013 by

June 14, 2013

By Medical Discovery News

The people who are at the highest risk of dying from common infections like pneumonia, influenza, and colds are 50 and older. Traditionally, scientists believed that as we age, our immune systems weaken, leaving us more vulnerable than ever to infections. But new research suggests that this isn’t completely true – certain parts of the immune system remain fully functional and robust longer.

It is true that older people make fewer antibodies, proteins that attach to viruses and cells infected with viruses to mark them for elimination by the immune system. This explains why some vaccines aren’t as effective in the elderly. The flu vaccine, for example, contains a “dead” virus that stimulates the body to make more protective antibodies against the flu.

However, other vaccines are well-received in older people, like the varicella zoster virus vaccine that prevents shingles. This vaccine does not involve antibodies, but T-cells, which kill infected cells, and memory T-cells, which recognize and respond to a reinfection.

White blood cells, formally called leukocytes, represent an army ready to defend the body from bacterial or viral attacks. T-cells are one type of soldier in this army, responsible for cellular immunity – killing infected cells to protect the body. The thymus, located between the breast bone and heart, produces T-cells. But as people age, the thymus does too.

The thymus shrinks by about 3 percent a year during middle age, and there is a corresponding fall in the production of T-cells. As humans age, their T-cells increasingly become memory cells. Therefore, it’s been assumed that the T-cell response to kill cells infected with a virus is impaired in older adults, making them more susceptible to viral infections.

To test that assumption, researchers at the McMaster Immunology Research Centre in Ontario isolated blood from people with one of three types of viral infections: West Nile Virus, Epstein-Barr Virus, and Cytomegalovirus. They divided the patients into three groups: those under 40, those middle-aged (41 – 59), and those over 60. They then measured the amount, type, and activity of the T-cells in each group. The older group did indeed have a shift toward the production of memory T-cells. But surprisingly, the amount of virus-specific T-cells did not decrease with age – the older group had roughly the same amount as the middle and younger groups.

These results suggest that the thymus continues to play an important role in producing T-cells that target viral infections as we age. It also indicates that vaccines designed to stimulate cellular immunity, instead of antibodies, would be more effective in older people. So the flu vaccine might prevent more flu cases in older people if the dead virus was replaced with a live but weakened virus, but currently that’s not approved in the U.S. for people over 50.

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