Anthrax in Cattle: The Risk to Humans

There are 3 main types of anthrax – cutaneous, gastrointestinal and respiratory. All three types of infection can occur in animals and humans. Spores are an important factor in transmitting infection, and animals usually become infected through grazing in areas where large numbers of spores are present in the surface of the soil (link to anthrax and cattle). Therefore natural infection in humans is not likely to occur unless they are in contact with infected animals or animal products.

Infection in animals is usually gastrointestinal, and the most likely route of infection in grazing animals is through ingestion of spores during dry periods following flooding. Spores are brought to the surface during periods of heavy rainfall and remain there and become concentrated during dry spells. Ingestion alone does not necessarily result in infection – the spores require a lesion of some sort to gain entry into the tissues. Gastrointetinal lesions may occur when grazing on dry, spiky, gritty grass that grows close to the soil – infection occurs where spores have also been deposited on the soil.

Grazing animals may also become infected through inhalation of spore-laden dust (pulmonary anthrax), although infection by this route is much less common than through ingestion. Animals that feed on the carcasses of dead animals can also become infected during outbreaks in grazing animals.

Humans become infected through contact with infected animals or animal products such as carcasses, hides, wool, hair and bone meal. Therefore, in areas where infection in livestock is uncommon, human infection is also rare.

The World Health Organization (WHO) reports higher incidence of infection in certain areas of Canada such as the MacKenzie Bison Range, North West Territory and Wood Buffalo National Park in northern Alberta, with sporadic outbreaks occurring in southern Alberta and Saskatchewan. In the U.S., sporadic cases occur in South Dakota, Nebraska and Oklahoma, with more persistent outbreaks in western Texas. In other areas of the world outbreaks occur more consistently – Central and South America, Mexico, South Africa, Middle East, Soviet Union, southern India, and south-east Asian countries (Vietnam, Cambodia, western China, Thailand).

The most common form of natural human infection is cutaneous anthrax, accounting for at least 95% of cases world-wide. Cutaneous anthrax is readily treated with penicillin and a number of other antibiotics. Without treatment, 10-20% of cutaneous infections may be life-threatening. Contact with the vegetative form of the bacteria in the fluids and tissues of sick or dying animals, or with spores in dead carcasses, meats, hides, hair, wool or bone does not guarantee infection. Infection requires a skin lesion (cut, scrape, etc.) in order to gain entry to the tissues. In 2-3 days (may occur as early as 9 hours or as long after as 7 days) a pimple-like red elevated area appears, followed 1-2 days later by a ring of blister-like, watery fluid-filled vesicles with swelling in the surrounding area. By 5-7 days, an ulcer forms (eschar) (see photo). By approximately 10 days, the eschar begins to heal and may take up to 6 weeks to resolve. Treatment at this stage does not speed healing. Without treatment a small number of cases may develop systemic infection.

Gastrointestinal and pulmonary anthrax have much higher mortality rates than cutaneous anthrax, often because they are more likely to go unrecognized and untreated. Treatment in the early stages of either infection is very effective; however, the disease progresses rapidly, and in the latter stages of infection treatment is often ineffective.

Gastrointestinal infection may occur following ingestion of raw or improperly cooked meat from sick or dead animals and symptoms are similar to other food-borne illnesses –

nausea, vomiting, fever, abdominal pain. Cases may be mild or severe – in severe cases the mortality rate is approximately 50% even with treatment.

Pulmonary anthrax is even more likely to be misdiagnosed as the initial stage of infection involves flu-like symptoms – mild fever, fatigue and malaise lasting one to several days. Without treatment at this stage, infection progresses rapidly to difficulty breathing, disorientation, toxemia and death. Naturally acquired pulmonary anthrax in humans is extremely rare.

Sea Turtles of Sipadan Island

A visitor to Sipadan Island (or Pulau Sipadan as it is locally known) is sure to see an abundance of marine life including whirling schools of barracuda, roaming sharks, and of course, plenty of sea turtles. Sipadan dive operators often boast that turtle sitings are guaranteed on their tours, and those boasts are not often wrong. Yet sea turtle populations throughout Malaysia continue to struggle, meaning Sipadan’s turtles must be studied and enjoyed with care.

Turtle Species of Pulau Sipadan

Malaysia is home to four species of turtle according to the WWF-Malaysia website (“What we do>Species>Turtles”). These include the Leatherback, Olive ridley, and Hawksbill turtles. The most abundant species however is the Green turtle – a creature which is actually black brown or greenish yellow in color. Regardless of its color this magnificent animal can grow to be four feet long and is quite an exciting find when visiting Sipadan dive sites.

It may be hard to recognize that all of Malaysia’s turtle species are endangered when visiting Sipadan. According to SCUBA diver and travel writer Jack Jackson in his book Diving with Giants as many as 30 turtles can be seen on a single dive in the month of August. This is peak egg laying season but each species of turtle uses Pulau Sipadan as a nesting site year round.

Sipadan Dive Sites and the Turtle Cavern

Sipadan Island is surrounded by beautiful dive sites most of which are home to large sea turtles. According to the online diver’s resource Asia Dive Site under its “Malaysia: Sipadan” entry, dive sites such as Coral Gardens, South Point, North Point, and Turtle Patch are all excellent places to go for turtle sitings. However, Sipadan’s most famous dive site is probably Turtle Cavern. A dark labyrinth of caves, Turtle Cavern was once thought to be the place where Sipadan turtles go to die. The cavern’s floor is littered with turtle skeletons and carcasses.

Unfortunately, the truth behind the cavern is quite chilling. According to Jack Jackson in Diving with Sharks and Other Adventure Dives, turtles use caves to rest in, but some turtles venture too far into the tunnels and, no longer able to see the light at the entrance become lost. Unable to find their way out, the turtles cannot surface to breathe, and thus drown within the cave system.

Visitors hoping to dive Sipadan will find a unique site at Turtle Cavern. However divers should approach the cave with caution so they do not meet the same fate as the unfortunate lost turtles.

Sea Turtle Conservation on Sipadan Island

Unfortunately, caves aren’t the greatest threats to turtles in Malaysia. Humans hunting turtles, developing resorts on their nesting sites, and accidentally catching them in fishing nets has driven all four species of Malaysia turtle onto the endangered species list. Recognizing this, the Malaysian government has taken steps to conserve turtles near Sipadan.

Asia Dive Site writes that, Sipadan has been declared a national park. All resorts that were on the island have left and the number of visitors to the island are restricted. These decisions seem to have helped Sipadan’s marine life writes the Borneo Post in “Marine Life Galore at Sipadan Island Marine Park”. The article writes how the Sipadan Island Marine Park Scientific Expedition found turtle populations increased since 2005 with 50-60 turtles seen in one day near their feeding area.

Neuroscience and the Neuronal Correlates of Consciousness

Neuroscience and the Brain

Even the most enthusiastic neuroscientist will concede that the human brain is not much to look at: a 1.5kg cauliflower of grey, spongy matter. But despite their modest outward appearance, our brains are the most complex objects known to man, and still represent the greatest problem in biology: how the timed firing of electrical signals from neurons, along with glial cells and neurotransmitters, can give rise to something as remarkably abstract as our own consciousness.

With recent advances in the field of neuroscience, the way we think about the way we think is changing, and the quest for the physical basis of consciousness promises to be a voyage of discovery as fascinating as the quest for the structure of DNA in the early 1950s. But what exactly are the problems facing neuroscientists, and how are these being solved today?

Defining Consciousness and Awareness

Perhaps the first issue is in defining consciousness itself. As human beings, we experience the world. When light of a certain wavelength hits the cone photoreceptors of our retina, we experience the sensation of seeing “red”, for instance, and we have feelings that correspond to this experience.

We are also probably not the only animals who experience the world in this way. Experimenting (humanely) with chimpanzees and dolphins has demonstrated that they are capable of complex, abstract tasks such as recognising themselves in mirrors (Gallup, 1970) and planning future actions (BBC), activities which should be impossible without some form of consciousness, or inner mental life.

Even the humble fruitfly has demonstrated that it is capable of complex behaviours involving choice (Heisenberg and Wolf, 1984). As such, Descarte’s idea of there being a “threshold of consciousness” over which only humanity has stepped has begun to sound as outdated as the concept of a geocentric universe.

Are Computers Conscious?

However, a neat sliding scale of consciousness also has its faults. Everyone has experienced what happens when a computer finds a fault in its hardware: you will likely receive a cryptic error message, or simply the “blue screen of death” as the damaged system struggles to function. But the idea that computers sense this line of code as analogous to pain, or that they experience the world on any level at all, can be discarded fairly quickly.

That is not to say that this suggestion does not have its proponents. Some scientists, like David Chalmers of the University of Arizona, postulate that all systems capable of processing information, even digital systems, are conscious in some sense, if only on a rudimentary level. Chalmers does concede, however, that it would probably not feel like much “to be a thermostat” (Koch & Krick).

Were this theory correct, it would suggest that our spinal columns, for instance, along with many parts of our brain and even the 100 million or so neurons found in the intestinal wall, could themselves be conscious. After all, they, too, process enormous amounts of information every second. If they are, of course, they are certainly not telling us about it!

Studying the Brain

One problem for scientists is that in-depth study of the brain is necessarily an invasive and life-threatening procedure. Much has been learnt from studies involving electrodes measuring the brain’s electrical field from outside the skull, but this is as problematic as trying to learn about the structure of the ocean by studying its waves.

As such, a vast majority of recent developments in the science of our own minds comes from what happens when they go wrong. Patients suffering massive epileptic seizures must undergo complicated surgery to have electrodes placed inside their brain in order to locate the troublesome tissue causing their seizures. This gives scientists a unique opportunity to study the way the brain works, and in particular how its workings give rise to consciousness.

The Clinton Neuron

One remarkable discovery has involved a specific neuron found in a seizure patient that fires whenever the subject sees a picture of former US president Bill Clinton. The patient was shown photographs of other white-haired men, other former presidents and hundreds of random control pictures, none of which elicited a response. Every time Mr. Clinton entered the subject’s field of view, the electrical readings from this single neuron spiked.

The implications of this are enormous, since it places the firing of neurons right at the start of the chain of mechanisms that create consciousness. When this neuron and the possibly hundreds of other “backup” duplicates fire, they somehow start a series of events that results in the patient recognising a face. But the question remains: how does this binary system of neurons either firing or remaining dormant create the almost infinite intricacies of our minds?

How Do Bacteria Make People Sick?: Bacterial Pathnogenicity, Virulence Factors and Infectious Disease

In order to cause disease, potentially harmful bacteria must first enter the body, usually through breaks in the skin, penetrating the mucous membrane or colonizing the gastrointestinal (GI) tract. This is considered infection, when bacteria breech the first line defenses of the body.

Bacterial disease starts with infection, but infection does not always result in disease. Many bacteria are beneficial. And even when pathogens infect the body, the immune system may be able to eliminate the infection before symptoms of disease occur.

Bacterial Pathogenicity and Virulence

To cause disease, bacteria must be present in sufficient numbers. But what is it about bacteria that make an infected person ill? Disease is not merely caused by the presence of microbes.

Pathogenicity (path-o-jen-ISS-ity) refers to a microbe’s ability to cause disease, and some microbes are more pathogenic—better able to cause disease—than others. The degree of a microbe’s pathogenicity is considered its “virulence.” For example, highly virulent bacteria frequently cause disease, whereas less virulent bacteria may only cause disease when present in large numbers or within hosts that have weakened immune systems.

Many pathogenic, or disease-causing bacteria have special weaponry, traits that enable them to infect and damage host tissue. These disease-causing traits are called “virulence factors”. The following sections describe different types of virulence factors.

Adhesion Factors, Glycocalyces and Biofilms

Once bacteria get into the body, they must be able to stick to the host’s cells in order to increase in number. Bacteria that are able to stick to host cells have special structures or chemicals, collectively called adhesion factors. These adhesins are found on bacterial cell extensions, such as fimbriae and flagella, and also on glycocalyces, a sticky layer surrounding some bacterial cells that enable bacteria to stick to surfaces and to each other in biofilms. For example, the inside of the mouth and teeth are covered with a sticky bacterial biofilm, particularly in the morning, before brushing, because bacteria have been multiplying in the mouth throughout the night.

Bacterial Extracellular Enzymes

Some pathogenic bacteria are able to produce and secrete enzymes that compromise cell structure of the host and enable the bacteria to work their way further into the body.

Bacterial Toxins

Bacteria may also produce toxins that cause damage to host cells either directly, by destroying tissue, or indirectly, by triggering an intense or prolonged host immune response. Bacterial toxins fall into two general categories based on their position relative to the cell that produces them; exotoxins, which are secreted by bacteria, and endotoxins, such as lipid-A, which are part of the Gram-negative bacterial cell.

Evading Host Immune System

The human immune system has special white blood cells called phagocytes, which search out, engulf and digest invading pathogens. The sooner a pathogen can be eliminated from the body, the less damage it will have the opportunity to cause. However, bacteria have developed means of evading phagocytes.

The bacterial capsule, a type of glycocalyx, can help a bacterium hide from the immune system. This coating is often made of chemicals that are found in the human body, and that don’t trigger an immune response.

Other bacteria produce chemicals that prevent them from being digested once engulfed by a phagocytic white blood cell, allowing the bacteria to live and reproduce inside the host cells designed to eliminate them. Other antiphagocytic chemicals can prevent bacteria from being engulfed by white blood cell, or can even destroy white blood cells.

Long Point Waterfowl A Leading Researcher: Ontario Organization Studies Waterfowl Issues

Based in Long Point, Ontario, Long Point Waterfowl is a non-profit, non-government organization dedicated to waterfowl and wetland-related research, conservation and training. Long Point Waterfowl also promotes Canada’s outdoor heritage.

Long Point Waterfowl was originally formed as Long Point Waterfowl and Wetlands Research Fund in the 1980s. Conservation-minded hunters at Bluff’s Club, a private hunting club on Long Point, were behind the efforts. Funding is still mainly from the Bluff’s Club members, but is also supported by Ducks Unlimited Canada, Waterfowl Research Foundation, Syndenham Conservation Foundation and the Ontario Federation of Anglers and Hunters.

The headquarters for Long Point Waterfowl is at Bird Studies Canada in Long Point, which is also the administrator.

The primary purpose of Long Point Waterfowl is to study the staging ecology and requirements of waterfowl on the lower Great Lakes. Long Point Waterfowl scientists also monitor trends in the distribution and abundance of waterfowl, research waterfowl habitat and provide information regarding waterfowl management.

Research results are published in scientific journals and presented at leading symposiums.

Long Point Waterfowl Research Centre

A former Ontario Youth Ranger Camp, Long Point Waterfowl leased this facility near Turkey Point as a place to host students and hold youth programs.

Youth Involvement In Conservation

One of the more unique events at Long Point Waterfowl is its young biologists workshop. This annual summer event is aimed at teenagers who are thinking of a future career as a biologist, conservation officers, wildlife technician or other related fields.

Participants learn about banding ducks, habitat, wildlife ecology, the role of hunting in conservation and a wide variety of other topics. The multi-day event includes meals and a stay at the Long Point Waterfowl Research Centre. Participants also learn about the educational requirements of future careers and hear from professionals in those fields.

Long Point Waterfowl also hosts a multi-day event where teenagers can stay at the centre and take all the training for their hunting certification.

Fund executive director Scott Petrie is also a teacher at the University of Western Ontario and sees that the students coming in don’t have the same background in the outdoors.

“Within our profession, people aren’t getting the training,” he said. “When I get a 22-year-old, they’re behind the eight-ball because they don’t have the passion.”

Research Projects at Long Point

Tundra swans are regular visitors to Long Point on their migration route from wintering grounds on the Atlantic seaboard to the high Arctic breeding grounds. Since little was known about these long-distant migrants, one of the first projects Petrie undertook was a satellite tracking study to learn more about tundra swan migration routes.

This was groundbreaking research, as such a study had never been undertaken with tundra swans in North America.

Resulting research has shown much about the swans, how much time they spent on migration, feeding habits along the way, when they arrive in the Arctic and much more. A map of the migration is available on Long Point Waterfowl’s web site

When a problem began to appear that numbers of lesser and greater scaup were declining relative to the health of other waterfowl species, Long Point Waterfowl again turned to satellite transmitters to learn more about the birds. This effort is still ongoing and is part of a cooperative venture between several research organizations investigating the problem.

Another major research initiative looked at the historical abundance and distribution of phragmites at Long Point. This tall grass with feather-like tops, an invasive species, was rapidly expanding at Long Point and displacing native vegetation. Research showed it is less preferable as waterfowl habitat than native vegetation. Other researchers have since identified it is a problem at other locations in Southwestern Ontario.

A current study is looking at the expanding population of Greater Sandhill Cranes in Ontario and the impact on agriculture.

Bruce Lipton’s The Biology of Belief: A Look at Unleashing the Power of Consciousness, Positive Thought

In the Biology of Belief, Bruce Lipton lays a scientific foundation that positive thoughts are a biological mandate for a happy, healthy life.

Bruce Lipton, Ph.D., is a cell biologist and his book The Biology of Belief: Unleashing the Power of Consciousness, Matter & Miracles is about how his work with cells led him to believe that genes and DNA do not control a person’s biology.

Rather, Lipton claims that signals from outside the cell, including the energy from positive and negative thoughts, control biology.

Lipton’s Theory on Cell Receptors

All cells have receptors that respond to their environment. For example, receptors detect estrogen, insulin, histamines, etc., which is how these substances affect the body’s cells. But not only do a cell’s receptors respond to physical substances, they also respond to vibrational energy fields such as light, sound, and radio frequencies.

Lipton’s research with cells led him to the conclusion that it is not the DNA in the cell’s nucleus that “programs” the cell, as traditionally believed, but the signals that come in through the cell’s receptors. That is, the physical and energetic environment controls the life of a cell.

Biology and Quantum Physics

According to quantum physics, physical atoms are made up of spinning, vibrating vortices of energy. Each atom has its own specific energy signature, and collections of atoms (molecules) have their own identifying energy patterns. All physical matter is made up of molecules, including human beings, and each piece of matter (or person) radiates its own unique energy signature.

Lipton points out that because Western biologists have ignored the energy component while focusing on the physical things that affect cells. Lipton claims that they have arrogantly dismissed 3,000 years of effective Eastern medicine as unscientific, even though it’s actually based on a deeper understanding of the universe. Lipton goes on to say that, “vibrational frequencies can alter the physical and chemical properties of an atom as surely as physical signals like histamine and estrogen.”

Thoughts and Perceptions

Lipton claims that cells respond to vibrational frequencies. Thoughts and perceptions are vibrational frequencies; therefore, cells respond to thoughts and perceptions. The problem is that not all a person’s thoughts and learned perceptions are accurate.

Biologically speaking, human brains have the ability to rapidly download “an unimaginable number of beliefs and behaviors into our memory.” The subconscious minds of young children become programmed with the fundamental behaviors, beliefs, and attitudes that are observed in their parents. These programs control a person’s biology for the rest of their lives, unless they consciously figure out a way to reprogram the mind.

A stimulus automatically engages the behavioral response that was learned when the signal was first experienced. Although the conscious mind can observe what is happening and step in and change the behavior, a person must be fully conscious. This can be difficult, which is why willpower so often fails.

Methods for Changing Perceptions

Although the Biology of Belief explains the science of why thoughts and perceptions are important, and even notes that a person can choose what to see, and choosing to look at negative rather than the positive aspects of life makes a person susceptible to disease,

Lipton doesn’t actually get into how to change thoughts and perceptions. However, many methods are available today to change beliefs, including Emotional Freedom Techniques (EFT), the Sedona Method or Abundance Course (also known as Lester Levenson’s Release Technique), Ho’oponopono, the Work of Byron Katie, and PSYCH-K.

Lipton concludes that because controlling perceptions equal beliefs, beliefs control biology. And that leads to the conclusions that learning to harness you mind to promote growth is the secret of life, and positive thoughts are a biological mandate for a happy, healthy life.

The Science of Autumn or Fall Leaves: Why Do Leaves Change Colour and Fall From the Trees?

Autumn’s beauty is clear for all to see, the myriad shades of red, yellow and brown lifting the heart on a cold but bright October morning. But the curious mind wonders “Why?” Why do the trees go through this process every year, only to grow fresh leaves every spring? And why such a variety of colours and shades – of which any artist would be proud?

Using Chlorophyll

The green leaves of summer contain chlorophyll, which drives photosynthesis – the molecular factory transforming carbon dioxide and light into glucose – which gives energy to the plant and cellulose for growth. When summer ends and autumn arrives, it is the short days which trigger the changes in deciduous trees. The chlorophyll is taken back from the leaves to be recycled, but the leaves become not just superfluous, but a liability.

Abscission Zones

In order to exert a force of suction, to draw water from the ground during the summer, leaves sweat through their high surface area. In winter these same leaves could cause the trees to dry out and die, so they must be removed. The scientific process of leaf-removal is known as abscission. When the shorter days of Autumn arrive, a number of chemical changes occur and the abscission zone at the base of the year begins to swell, cutting off the flow of nutrients from the tree to the leaf and vice-versa. The zone then begins to tear, the leaf falls off or is blown away, and a protective layer seals the wound, preventing water evaporation and entry of bugs.

Anthocyanins and Aphids

But why do the leaves go so many different colours? The removal of the chlorophyll reveals other colours in the leaf – yellow, orange and brown – but some leaves turn red or purple for another important reason. The shorter days which trigger the process of abscission, also initiate another process in the leaves of certain trees to produce a group of chemicals called anthocyanins, which are deep red or purple in colour. This is not, however, just vanity on behalf of the tree.

In fact, the red colours are used to conceal the shades of yellow which attract aphids. So, trees which are more susceptible to aphids, or are native to areas where aphids are more of a problem, are able to confuse their enemies and survive to grace another spring.

How Did Recombinant DNA Start? Cutting and Pasting of DNA Molecules in the Laboratory

A series of critical scientific discoveries were required before the manipulation and propagation of engineered DNA molecules could be undertaken.

The DNA molecule was discovered in the mid-1800s. It was not proven to be critical to the mechanisms of inheritance until the 1940s. Since the 1950s, and the seminal work of Watson and Crick to characterize the chemical structure of DNA and how it could be copied, the understanding of the biochemistry of DNA and the ability to manipulate it in the laboratory has grown exponentially. Breakthroughs studying DNA now come fast and furious, but several key discoveries are largely responsible for the development of modern recombinant DNA technology.

The Genetic Code

Knowing that DNA is the molecule of heredity is one thing. Knowing how it maintains and transmits crucial genetic information is something else entirely. In the early 1960s, Marshall Nirenberg and colleagues working at the US National Institutes of Health cracked the genetic code. Using synthetic RNA molecules and radioactively labeled amino acids they proved that DNA used a three letter code (three nucleotide bases made a “codon”) to specify individual amino acids, the codons in RNA molecules were contiguous, they did not overlap, and there were punctuation marks, places specifying “start” and “stop”.

Episomes and Plasmid DNA

In the 1950s and 1960s, numerous scientists were studying how DNA was handled in bacteria, viruses and yeast. From their combined work came the knowledge that bacteria could carry small, circular molecules of DNA that were not integrated as part of their chromosomal DNA. Most important of all, these “plasmids” or “episomes” could be isolated and more importantly they could be transferred back into other bacteria.

Restriction Endonucleases

One of the key factors in recombinant DNA technology is the ability to “cut” DNA molecules and to be able to “paste” pieces together, often in a new order. Werner Arber, a Swiss microbiologist, was the first to recognize that there were enzymes that would cut DNA molecules in specific ways. Shortly after this work was published studying the bacterium E. coli, Hamilton Smith and colleagues identified a “restriction endonuclease” from another bacterium, Haemophilusinfluenza, and then showed that it cut at a very specific sequence of DNA bases. Today there are hundreds of restriction enzymes known to cut DNA at specific occurrences of base sequences.

Recombinant DNA Molecules

In 1972, scientists Herbert Boyer and Stanley Cohen were in Hawaii attending a scientific meeting about plasmids when they met to discuss the work that they were each pursuing. What ultimately came from this meeting was the birth of recombinant DNA cloning, the start of the biotechnology industry and a new era in molecular biology. Collaborating on the use of newly identified restriction enzymes and DNA manipulation techniques, they published seminal papers showing that DNA from one source could be cut with restriction enzymes and then placed into the midst of cut DNA from another source, and these could be placed into bacteria and grow stably with the “recombined” DNA maintained in the newly arranged form.

Herbert Boyer went on to found the biotech company Genentech and the research world has never been the same. Recombinant DNA methods are now used to make things from insulin for diabetics to proteins that can make individual cells, or even whole organisms, glow green, blue or red under just the right light. Remarkable.

To read more about the cracking of the genetic code by Nirenberg and colleagues visit the history page at the US National Institutes of Health.

Antibiotic Susceptibility Tests – Types and Ways: Antibiotic Evaluation, Antimicrobial Effectiveness In Vitro In Vivo

Proper antibiotic susceptibility testing of microbial pathogens isolated from patients is critical. The use of an ineffective antibiotic could lead to a patient’s death

Today, if someone gets a bacterial infectious disease the first thought is “what antibiotic will help or work?” The doctor and the patient both desire the best and most effective antibiotic. This is what makes testing and analysis of antibiotics very interesting.

In the 1950’s and 60’s there were sufficient antibiotics on the medical scene to require a closer look at standardized testing of antibiotics. A better way was sought to accurately and precisely forecast which antibiotic would work and which would not.

Drs. Kirby, Bauer, and Sherris established a defined scientific approach to antibiotic testing (KBS technique) . This greatly improved the accuracy and results of testing. There are several important ways to determine antibiotic susceptibility.

Solid, Liquid and Animal Tests of Antibiotics

  • When chemicals and antibiotics were first tested they were added to nutrient agar petri dishes (circular glass, or plastic, with larger top glass cover overlapping a bottom reservoir) with bacteria streaked over the surface. The next day a zone of inhibition was looked for as shown in figures below (click to enlarge these figures).
  • Bacteria can also be tested in test tubes with nutrient broth. Sequential dilutions of the chemical or antibiotic are done first, followed by addition of a measured bacterial inoculum to each tube. After overnight incubation the tubes are analyzed: clear tubes indicate inhibition and cloudy tubes indicate bacteria not inhibited by that concentration or titer of antibiotic. In this way scientists can correlate later how much antibiotic yields what zone size on agar.
  • The zone sizes produced on plates by dropped antibiotic disks are plotted versus the amount in the disk. Simply, this is a regression analysis graph. It is possible to establish MIC (minimum inhibitory concentration) values in broth, blood or serum in this way. Typically, the more resistant a microbe is the smaller the zone. The more susceptible, the bigger the zone.
  • Finally, if an antibiotic looks promising, it can be tested in mice or rabbits for toxicity (harmful) and effectiveness.

Measurement of the amount of antibiotic injected, or ingested, is the dose. The antibiotic titer is the MIC = minimum inhibitory concentration ( an actual value attainable in blood or serum). MIC is measured in micrograms or units. MIC can be evaluated in blood and tissue fluids . The higher the MIC the more resistant the bacterium is to that antibiotic.

Standardized Antibiotic Testing

Antibiotic testing should always be done with a pure culture of the organism.

The KBS technique eliminates the variables that affect the zone size and could cause false positives or false negatives.

The agar used is Mueller-Hinton. The depth and pH of the agar,inoculum size and incubation temperature are standardized. The click-on photos below show several things:

  • different antibiotics have characteristic zone sizes for MIC
  • the same antibiotic at different concentrations will give different zone diameters
  • resistant bacteria cause zone size decreases. No zone = complete resistance
  • regression analyses enable microbiologists to determine MIC vs disk zones
  • populations of the same species vary from susceptible (S) to intermediate (I) to resistant R)

Recently, the valuable E-test (see photo) allows determination of MIC of a microbe with one disk that forms an antibiotic gradient. This permits rapid, clear medical evaluations of antibiotic effectiveness.

Review of the Primer of Conservation Biology: A Teaching Tool on the Topic of Conservation Biology

Learning about conservation biology is the first step to making a difference, and through the text by Richard B. Primack that becomes possible.

Conservation biology is the field that seeks to study and protect the living world and its biological diversity. So says Richard B. Primack at in the prefix of his book called A Primer of Conservation Biology. His intent with that statement is to provide a specific definition of what conservation biology is, and to lay the beginning framework of what the rest of his book is about.

What is Conservation Biology?

Conservation Biology is still a relatively new field, because there hasn’t always been a movement to save the Earth. Resources are burnt thorough quite quickly, and in doing so the environment is hurt in more ways than one. No matter what side of the “environmental argument” someone’s on, there is debate that the planet is being harmed more every day. What Primack hopes to do with this book, is to show what is happening, and what people interested in the field can do about it.

Thoughts on Conservation Biology

The first part of the book describes conservation, and why it is needed. Resource management is a huge step in the right direction and the methods to do it are explained with depth. This is a great section about exactly what is being done wrong, and where the mistakes can be fixed if subtle changes are made in the way that people do things. The text relates about extinctions that are taking place all the time, and the rates at which those extinctions are occurring.

From there he goes into discussions about the threats to biological diversity that are beginning to happen as more and more species are threatened. Those aren’t just limited to the larger animals that are in the news, but plants, bugs, and even microscopic creatures that depend on other species to keep living. He also gives examples of why these extinctions are happening.

Putting Conservation Biology into Practice

Conservation at the population and species level, and conserving biological communities are what Primack dives into as the book progresses. He shows how designing networks of protected areas, and managing them, along with ecological restoration of those areas that some of these problems can be slowed down. Conservation isn’t something that can be implemented right away, and it’s key to take the steps and put the procedures in place so that it can become something that everyone focuses on more.

Through the roles of agencies (both public and private) and through Government programs conservation is becoming something more center-stage to the public. The key here is to learn as much as possible about the field to get involved in helping conservation, and Primack’s book is a good stepping off point.

Primack explains the terms well, and the theories and facts of everything he talks about are phrased so even the most novice reader can understand. The entire book does a great job of telling the reader the basics of conservation, what has been implemented so far, and what still needs to be done for it to all work out. Conservation Biology is an important field that is slowly becoming more popular as people realize just how badly the environment is being treated.

Final Recommendation on the Primer of Conservation Biology

For those interested in anything to do with conservation, this is a great tool to provide knowledge that would be necessary to be active. The book comes in at 320 pages, is paper back, and can be found online or in most bookstores. It is highly recommend it to anyone wanting to read more about conservation biology.