Which prokaryotes cause disease

These bacteria are spread by skin-to-skin contact between an uninfected person and a skin lesion, called a chancre, on an infected person. Treponema pallidum replicate rapidly at the site of infection, producing a lesion called a canker. They enter the bloodstream and then spread to other tissues. Syphilis becomes deadly when it reaches the brain. Lyme disease—named for Lyme, Connecticut—is spread by tick bites, but caused by the spirochete, Borrelia burgdorferi. The bacteria that cause Lyme disease prefer to live in deer, but can also live in humans where they cause flu-like symptoms.

As Lyme disease develops further, it ultimately causes arthritis-like stiffness. The deer ticks that spread Lyme disease are called vectors , while deer are considered a reservoir for the bacterium.

Just like most reservoirs hold extra water, deer serve as a constant stockpile of source of Lyme-disease-causing bacteria. Check out the ring pattern that follows a bite by Lyme-disease-carrying tick as well as a microscope image of Borrelia burgdorferi.

Just like Borrellia burgdorferi bacteria normally live in deer, the bacteria that cause Legionnaires' disease, Legionella pneumophila , typically inhabit single-celled amoeba cells. Here is an amoeba cell grabbing a Legionella cell. You might remember it from the opening of the chapter.

Legionella bacteria enter the body through inhalation of small droplets in liquid called aerosols into the lungs. The disease was unknown until it first struck at an American Legion convention in Philadelphia in It was long thought that ulcers happened from stress or consuming spicy foods. Biologists in the 19th century had noticed some spiral-shaped bacteria in the stomachs of patients with ulcers, but were unable to show a link between the bacteria and the disease.

Marshall tried several different methods until he was able to culture enough of the bacteria, called Helicobacter pylori , to test if it caused ulcers. Think about that for a second. Marshall got his wish—and a Nobel Prize. Within a week, he began to develop stomach ulcers, and he saw an increase in the Helicobacter pylori in his stomach.

Happily, antibiotic consumption killed off the bacteria in his stomach as well as those of other patients with ulcers. These other patients got the ulcers by the old fashioned way, which is still unknown. Stress and poor health habits are general risk factors for disease susceptibility. This may be especially true in the case of ulcers, where many people believed that ulcers were only caused by stress, with no infectious disease component. So in this section, we talked about a few different kinds of bacterial infections, all of them are transmitted through different means.

To review:. Scientists are still investigating how Helicobacter pylori , which cause ulcers, are spread. Some scientists believe it is through saliva, while others believe it may be spread by flies. Understanding the cause of disease affects how they are treated. Rather than focusing on antibiotics, regions with high rates of cholera should probably focus on their water supply, while communities with incidence of Lyme disease might want to look towards controlling the deer or tick population.

He used it in the title of his epic poem, "Syphilis, or the French Disease" which tells the story of a young shepherd named Syphilus who insulted the sun god and was given the disease syphilis as punishment.

Find out more about this here. Parents Home Homeschool College Resources. Most E. All types of food can potentially be contaminated with bacteria. Recent outbreaks of Salmonella reported by the CDC occurred in foods as diverse as peanut butter, alfalfa sprouts, and eggs. A deadly outbreak in Germany in was caused by E. The strain that caused the outbreak was found to be a new serotype not previously involved in other outbreaks, which indicates that E.

Outbreaks of listeriosis, due to contamination of meats, raw cheeses, and frozen or fresh vegetables with Listeria monocytogenes , are becoming more frequent.

Recall that biofilms are microbial communities that are very difficult to destroy. They produce dental plaque and colonize catheters, prostheses, transcutaneous and orthopedic devices, contact lenses, and internal devices such as pacemakers.

They also form in open wounds and burned tissue. In healthcare environments, biofilms grow on hemodialysis machines, mechanical ventilators, shunts, and other medical equipment. In fact, 65 percent of all infections acquired in the hospital nosocomial infections are attributed to biofilms.

Biofilm infections develop gradually and may not cause immediate symptoms. They are rarely resolved by host defense mechanisms. Once an infection by a biofilm is established, it is very difficult to eradicate, because biofilms tend to be resistant to most methods used to control microbial growth, including antibiotics.

The matrix that attaches the cells to a substrate and to other another protects the cells from antibiotics or drugs. In addition, since biofilms grow slowly, they are less responsive to agents that interfere with cell growth. It has been reported that biofilms can resist up to 1, times the antibiotic concentrations used to kill the same bacteria when they are free-living or planktonic.

An antibiotic dose that large would harm the patient; therefore, scientists are working on new ways to get rid of biofilms. Are the antibiotics that easily treated bacterial infections in the past becoming obsolete?

Is this the beginning of the end of antibiotics? All these questions challenge the healthcare community. One of the main causes of antibiotic resistance in bacteria is overexposure to antibiotics. The imprudent and excessive use of antibiotics has resulted in the natural selection of resistant forms of bacteria. The antibiotic kills most of the infecting bacteria, and therefore only the resistant forms remain.

These resistant forms reproduce, resulting in an increase in the proportion of resistant forms over non-resistant ones. In addition to transmission of resistance genes to progeny, lateral transfer of resistance genes on plasmids can rapidly spread these genes through a bacterial population. A major misuse of antibiotics is in patients with viral infections like colds or the flu, against which antibiotics are useless. Another problem is the excessive use of antibiotics in livestock.

The routine use of antibiotics in animal feed promotes bacterial resistance as well. In the United States, 70 percent of the antibiotics produced are fed to animals. These antibiotics are given to livestock in low doses, which maximize the probability of resistance developing, and these resistant bacteria are readily transferred to humans. Watch a recent news report on the problem of routine antibiotic administration to livestock and antibiotic-resistant bacteria.

The imprudent use of antibiotics has paved the way for the expansion of resistant bacterial populations. However, a very dangerous strain, methicillin-resistant Staphylococcus aureus MRSA has made the news over the past few years Figure. This strain is resistant to many commonly used antibiotics, including methicillin, amoxicillin, penicillin, and oxacillin. MRSA can cause infections of the skin, but it can also infect the bloodstream, lungs, urinary tract, or sites of injury.

Researchers have expressed concern about the way this latter source of MRSA targets a much younger population than those residing in care facilities. Comparison of community- and health care-associated methicillin-resistant Staphylococcus aureus infection.

JAMA : —84, doi: In summary, the medical community is facing an antibiotic crisis. Some scientists believe that after years of being protected from bacterial infections by antibiotics, we may be returning to a time in which a simple bacterial infection could again devastate the human population.

Researchers are developing new antibiotics, but it takes many years of research and clinical trials, plus financial investments in the millions of dollars, to generate an effective and approved drug. Epidemiologist Epidemiology is the study of the occurrence, distribution, and determinants of health and disease in a population. It is, therefore, part of public health. An epidemiologist studies the frequency and distribution of diseases within human populations and environments.

Epidemiologists collect data about a particular disease and track its spread to identify the original mode of transmission.

They sometimes work in close collaboration with historians to try to understand the way a disease evolved geographically and over time, tracking the natural history of pathogens. They gather information from clinical records, patient interviews, surveillance, and any other available means. That information is used to develop strategies, such as vaccinations Figure , and design public health policies to reduce the incidence of a disease or to prevent its spread.

Epidemiologists also conduct rapid investigations in case of an outbreak to recommend immediate measures to control it. Many epidemiologists are also physicians and have an M. O degree , or they have a Ph.

Some prokaryotes are human pathogens. Devastating diseases and plagues have been among us since early times and remain among the leading causes of death worldwide. Emerging diseases are those rapidly increasing in incidence or geographic range. They can be new or re-emerging diseases previously under control. Many emerging diseases affecting humans originate in animals zoonoses , such as brucellosis.

A group of re-emerging bacterial diseases recently identified by WHO for monitoring include bubonic plague, diphtheria, and cholera. Foodborne diseases result from the consumption of food contaminated with food, pathogenic bacteria, viruses, or parasites. Biofilms can grow on human tissues, like dental plaque; colonize medical devices; and cause infection or produce foodborne disease by growing on the surfaces of food and food-processing equipment.

Biofilms are resistant to most of the methods used to control microbial growth. The excessive use of antibiotics has resulted in a major global problem, since resistant forms of bacteria have been selected over time. A very dangerous strain, methicillin-resistant Staphylococcus aureus MRSA , has wreaked havoc recently across the world.

A person in England arrives at a medical clinic with a fever and swollen lymph nodes shortly after returning from a visit to New Mexico. Outbreaks of bacterial infection related to food consumption are common. The characteristics of foodborne illnesses have changed over time. In the past, it was relatively common to hear about sporadic cases of botulism , the potentially fatal disease produced by a toxin from the anaerobic bacterium Clostridium botulinum.

A can, jar, or package created a suitable anaerobic environment where Clostridium could grow. Proper sterilization and canning procedures have reduced the incidence of this disease.

Most cases of foodborne illnesses are now linked to produce contaminated by animal waste. For example, there have been serious, produce-related outbreaks associated with raw spinach in the United States and with vegetable sprouts in Germany [Figure 7].

The raw spinach outbreak in was produced by the bacterium E. Most E. All types of food can potentially be contaminated with harmful bacteria of different species. Recent outbreaks of Salmonella reported by the CDC occurred in foods as diverse as peanut butter, alfalfa sprouts, and eggs. Epidemiologist Epidemiology is the study of the occurrence, distribution, and determinants of health and disease in a population.

It is, therefore, related to public health. An epidemiologist studies the frequency and distribution of diseases within human populations and environments. Epidemiologists collect data about a particular disease and track its spread to identify the original mode of transmission.

They sometimes work in close collaboration with historians to try to understand the way a disease evolved geographically and over time, tracking the natural history of pathogens.

They gather information from clinical records, patient interviews, and any other available means. That information is used to develop strategies and design public health policies to reduce the incidence of a disease or to prevent its spread.

Epidemiologists also conduct rapid investigations in case of an outbreak to recommend immediate measures to control it. Epidemiologists typically have a graduate-level education. Many epidemiologists are also physicians and have an MD or they have a PhD in an associated field, such as biology or epidemiology. Not all prokaryotes are pathogenic.

On the contrary, pathogens represent only a very small percentage of the diversity of the microbial world. In fact, our life and all life on this planet would not be possible without prokaryotes.

Genetic engineering, artificial selection, antibiotic production, and cell culture are current topics of study in biotechnology. However, humans have used prokaryotes to create products before the term biotechnology was even coined. And some of the goods and services are as simple as cheese, yogurt, sour cream, vinegar, cured sausage, sauerkraut, and fermented seafood that contains both bacteria and archaea [Figure 8]. Cheese production began around 4, years ago when humans started to breed animals and process their milk.

Evidence suggests that cultured milk products, like yogurt, have existed for at least 4, years. Microbial bioremediation is the use of prokaryotes or microbial metabolism to remove pollutants. Bioremediation has been used to remove agricultural chemicals pesticides and fertilizers that leach from soil into groundwater.

Certain toxic metals, such as selenium and arsenic compounds, can also be removed from water by bioremediation. Mercury is an example of a toxic metal that can be removed from an environment by bioremediation. Mercury is an active ingredient of some pesticides; it is used in industry and is also a byproduct of certain industries, such as battery production. Mercury is usually present in very low concentrations in natural environments but it is highly toxic because it accumulates in living tissues.

Several species of bacteria can carry out the biotransformation of toxic mercury into nontoxic forms. Probably one of the most useful and interesting examples of the use of prokaryotes for bioremediation purposes is the cleanup of oil spills. The importance of prokaryotes to petroleum bioremediation has been demonstrated in several oil spills in recent years, such as the Exxon Valdez spill in Alaska [Figure 9] , the Prestige oil spill in Spain , the spill into the Mediterranean from a Lebanon power plant , and more recently, the BP oil spill in the Gulf of Mexico To clean up these spills, bioremediation is promoted by adding inorganic nutrients that help bacteria already present in the environment to grow.

Hydrocarbon-degrading bacteria feed on the hydrocarbons in the oil droplet, breaking them into inorganic compounds. Some species, such as Alcanivorax borkumensis , produce surfactants that solubilize the oil, while other bacteria degrade the oil into carbon dioxide. In the case of oil spills in the ocean, ongoing, natural bioremediation tends to occur, inasmuch as there are oil-consuming bacteria in the ocean prior to the spill.

Under ideal conditions, it has been reported that up to 80 percent of the nonvolatile components in oil can be degraded within 1 year of the spill. Other oil fractions containing aromatic and highly branched hydrocarbon chains are more difficult to remove and remain in the environment for longer periods of time.

Researchers have genetically engineered other bacteria to consume petroleum products; indeed, the first patent application for a bioremediation application in the U. Humans are no exception when it comes to forming symbiotic relationships with prokaryotes. We are accustomed to thinking of ourselves as single organisms, but in reality, we are walking ecosystems. There are 10 to times as many bacterial and archaeal cells inhabiting our bodies as we have cells in our bodies.

Some of these are in mutually beneficial relationships with us, in which both the human host and the bacterium benefit, while some of the relationships are classified as commensalism , a type of relationship in which the bacterium benefits and the human host is neither benefited nor harmed. Human gut flora lives in the large intestine and consists of hundreds of species of bacteria and archaea, with different individuals containing different species mixes.

The primary functions of these prokaryotes for humans appear to be metabolism of food molecules that we cannot break down, assistance with the absorption of ions by the colon, synthesis of vitamin K, training of the infant immune system, maintenance of the adult immune system, maintenance of the epithelium of the large intestine, and formation of a protective barrier against pathogens.

The surface of the skin is also coated with prokaryotes. The different surfaces of the skin, such as the underarms, the head, and the hands, provide different habitats for different communities of prokaryotes. Unlike with gut flora, the possible beneficial roles of skin flora have not been well studied.

However, the few studies conducted so far have identified bacteria that produce antimicrobial compounds as probably responsible for preventing infections by pathogenic bacteria. Researchers are actively studying the relationships between various diseases and alterations to the composition of human microbial flora.

Prokaryotes existed for billions of years before plants and animals appeared. Microbial mats are thought to represent the earliest forms of life on Earth, and there is fossil evidence, called stromatolites, of their presence about 3. During the first 2 billion years, the atmosphere was anoxic and only anaerobic organisms were able to live. Cyanobacteria began the oxygenation of the atmosphere.

Prokaryotes domains Archaea and Bacteria are single-celled organisms lacking a nucleus. They have a single piece of circular DNA in the nucleoid area of the cell. Most prokaryotes have cell wall outside the plasma membrane. Bacteria and Archaea differ in the compositions of their cell membranes and the characteristics of their cell walls. Bacterial cell walls contain peptidoglycan. Archaean cell walls do not have peptidoglycan.

Bacteria can be divided into two major groups: Gram-positive and Gram-negative. Gram-positive organisms have a thick cell wall. Gram-negative organisms have a thin cell wall and an outer membrane. Prokaryotes use diverse sources of energy to assemble macromolecules from smaller molecules. Phototrophs obtain their energy from sunlight, whereas chemotrophs obtain it from chemical compounds.

Infectious diseases caused by bacteria remain among the leading causes of death worldwide. The excessive use of antibiotics to control bacterial infections has resulted in resistant forms of bacteria being selected.

Foodborne diseases result from the consumption of contaminated food, pathogenic bacteria, viruses, or parasites that contaminate food. Prokaryotes are used in human food products. Microbial bioremediation is the use of microbial metabolism to remove pollutants.

The human body contains a huge community of prokaryotes, many of which provide beneficial services such as the development and maintenance of the immune system, nutrition, and protection from pathogens. Explain the reason why the imprudent and excessive use of antibiotics has resulted in a major global problem.

Antibiotics kill bacteria that are sensitive to them; thus, only the resistant ones will survive. These resistant bacteria will reproduce, and therefore, after a while, there will be only resistant bacteria, making it more difficult to treat the diseases they may cause in humans. Your friend believes that prokaryotes are always detrimental and pathogenic.