File Name: types of pathogens and diseases they cause .zip
- A Guide to Different Types of Pathogens
- What to know about infections
- A Guide to Different Types of Pathogens
- What You Need to Know About Pathogens and the Spread of Disease
A Guide to Different Types of Pathogens
Pathogenic bacteria are bacteria that can cause disease. Although most bacteria are harmless or often beneficial, some are pathogenic , with the number of species estimated as fewer than a hundred that are seen to cause infectious diseases in humans. One of the bacterial diseases with the highest disease burden is tuberculosis , caused by Mycobacterium tuberculosis bacteria, which kills about 2 million people a year, mostly in sub-Saharan Africa.
Pathogenic bacteria contribute to other globally important diseases, such as pneumonia , which can be caused by bacteria such as Streptococcus and Pseudomonas , and foodborne illnesses , which can be caused by bacteria such as Shigella , Campylobacter , and Salmonella. Pathogenic bacteria also cause infections such as tetanus , typhoid fever , diphtheria , syphilis , and leprosy.
Pathogenic bacteria are also the cause of high infant mortality rates in developing countries. Koch's postulates are the standard to establish a causative relationship between a microbe and a disease. Each species has specific effect and causes symptoms in people who are infected. Some, if not most people who are infected with a pathogenic bacteria do not have symptoms.
Immunocompromised individuals are more susceptible to pathogenic bacteria. Some pathogenic bacteria cause disease under certain conditions, such as entry through the skin via a cut, through sexual activity or through a compromised immune function.
Streptococcus and Staphylococcus are part of the normal skin microbiota and typically reside on healthy skin or in the nasopharangeal region. Yet these species can potentially initiate skin infections. They are also able to cause sepsis , pneumonia or meningitis. These infections can become quite serious creating a systemic inflammatory response resulting in massive vasodilation, shock, and death. Other bacteria are opportunistic pathogens and cause disease mainly in people suffering from immunosuppression or cystic fibrosis.
Examples of these opportunistic pathogens include Pseudomonas aeruginosa , Burkholderia cenocepacia , and Mycobacterium avium. Obligate intracellular parasites e. Chlamydophila , Ehrlichia , Rickettsia have the ability to only grow and replicate inside other cells.
Even these intracellular infections may be asymptomatic , requiring an incubation period. An example of this is Rickettsia which causes typhus. Another causes Rocky Mountain spotted fever. Chlamydia is a phylum of intracellular parasites. These pathogens can cause pneumonia or urinary tract infection and may be involved in coronary heart disease.
Other groups of intracellular bacterial pathogens include Salmonella , Neisseria , Brucella , Mycobacterium , Nocardia , Listeria , Francisella , Legionella , and Yersinia pestis. These can exist intracellularly, but can exist outside of host cells. Bacterial pathogens often cause infection in specific areas of the body.
Others are generalists. The symptoms of disease appear as pathogenic bacteria damage host tissues or interfere with their function. The bacteria can damage host cells directly. They can also cause damage indirectly by provoking an immune response that inadvertently damages host cells.
Once pathogens attach to host cells, they can cause direct damage as the pathogens use the host cell for nutrients and produce waste products. The acid decalcifies the tooth surface to cause dental caries.
Endotoxins are the lipid portions of lipopolysaccharides that are part of the outer membrane of the cell wall of gram-negative bacteria. Endotoxins are released when the bacteria lyses , which is why after antibiotic treatment, symptoms can worsen at first as the bacteria are killed and they release their endotoxins. Exotoxins are secreted into the surrounding medium or released when the bacteria die and the cell wall breaks apart.
An excessive or inappropriate immune response triggered by an infection may damage host cells. Iron is required for humans, as well as the growth of most bacteria. To obtain free iron, some pathogens secrete proteins called siderophores , which take the iron away from iron-transport proteins by binding to the iron even more tightly.
Once the iron-siderophore complex is formed, it is taken up by siderophore receptors on the bacterial surface and then that iron is brought into the bacterium. Typically identification is done by growing the organism in a wide range of cultures which can take up to 48 hours.
The growth is then visually or genomically identified. The cultured organism is then subjected to various assays to observe reactions to help further identify species and strain. Bacterial infections may be treated with antibiotics , which are classified as bacteriocidal if they kill bacteria or bacteriostatic if they just prevent bacterial growth. There are many types of antibiotics and each class inhibits a process that is different in the pathogen from that found in the host.
For example, the antibiotics chloramphenicol and tetracyclin inhibit the bacterial ribosome but not the structurally different eukaryotic ribosome, so they exhibit selective toxicity. Both uses may be contributing to the rapid development of antibiotic resistance in bacterial populations. Infections can be prevented by antiseptic measures such as sterilizing the skin prior to piercing it with the needle of a syringe and by proper care of indwelling catheters.
Surgical and dental instruments are also sterilized to prevent infection by bacteria. Disinfectants such as bleach are used to kill bacteria or other pathogens on surfaces to prevent contamination and further reduce the risk of infection. Many genera contain pathogenic bacterial species. They often possess characteristics that help to classify and organize them into groups. The following is a partial listing.
This is description of the more common genera and species presented with their clinical characteristics and treatments. Contact with cattle, sheep, goats and horses  Spores enter through inhalation or through abrasions . Penicillin Doxycycline Ciprofloxacin Raxibacumab .
Anthrax vaccine  Autoclaving of equipment . Aspiration prevention . Contact with respiratory droplets expelled by infected human hosts. Whooping cough   Secondary bacterial pneumonia . Pertussis vaccine ,   such as in DPT vaccine  . Ixodes hard ticks Reservoir in mice, other small mammals, and birds . Lyme disease  . Doxycycline for adults, amoxicillin for children, ceftriaxone for neurological involvement .
Wearing clothing that limits skin exposure to ticks. Better access to washing facilities  Reduce crowding  Pesticides . Direct contact with infected animal  Oral, by ingestion of unpasteurized milk or milk products . Brucellosis : mainly fever , muscular pain and night sweats. Fecal-oral from animals mammals and fowl   Uncooked meat especially poultry   Contaminated water .
Treat symptoms  Fluoroquinolone  such as ciprofloxacin  in severe cases . Good hygiene  Avoiding contaminated water  Pasteurizing milk and milk products  Cooking meat especially poultry . Respiratory droplets  . Doxycycline   Erythromycin  . Trachoma   Neonatal conjunctivitis   Neonatal pneumonia   Nongonococcal urethritis NGU   Urethritis   Pelvic inflammatory disease   Epididymitis   Prostatitis   Lymphogranuloma venereum LGV  .
Erythromycin   adults  Doxycycline   infants and pregnant women . Erythromycin or silver nitrate in newborn 's eyes  Safe sex  Abstinence . Tetracycline  Doxycycline  Erythromycin . Botulism : Mainly muscle weakness and paralysis .
Antitoxin   Penicillin  Hyperbaric oxygen  Mechanical ventilation . Gut flora ,   overgrowing when other flora is depleted . Pseudomembranous colitis  . Discontinuing responsible antibiotic   Vancomycin or metronidazole if severe  .
Spores in soil   Vaginal flora and gut flora . Anaerobic cellulitis   Gas gangrene   Acute food poisoning  . Debridement or amputation   Hyperbaric medicine   High doses of doxycycline  or penicillin G   and clindamycin  Food poisoning: Supportive care is sufficient .
Spores in soil, skin penetration through wounds  . Tetanus : muscle spasms . Tetanus immune globulin   Sedatives  Muscle relaxants  Mechanical ventilation   Penicillin or metronidazole . Tetanus vaccine such as in the DPT vaccine . Diphtheria : Fever , sore throat and neck swelling, potentially narrowing airways.
Horse serum antitoxin Erythromycin Penicillin. Part of gut flora ,  opportunistic or entering through GI tract or urinary system wounds . Bacterial endocarditis ,  biliary tract infections,  urinary tract infections . Ampicillin combined with aminoglycoside in endocarditis  Vancomycin . No vaccine Hand washing and other nosocomial prevention. Meningitis: . Diarrhea: .
Heating water . Prevention of exposure .
What to know about infections
NCBI Bookshelf. New York: Garland Science; Infectious disease can be devastating, and sometimes fatal, to the host. In this part of the chapter we will briefly examine the stages of infection, and the various types of infectious agents. The process of infection can be broken down into stages, each of which can be blocked by different defense mechanisms.
Pathogenic bacteria are bacteria that can cause disease. Although most bacteria are harmless or often beneficial, some are pathogenic , with the number of species estimated as fewer than a hundred that are seen to cause infectious diseases in humans. One of the bacterial diseases with the highest disease burden is tuberculosis , caused by Mycobacterium tuberculosis bacteria, which kills about 2 million people a year, mostly in sub-Saharan Africa. Pathogenic bacteria contribute to other globally important diseases, such as pneumonia , which can be caused by bacteria such as Streptococcus and Pseudomonas , and foodborne illnesses , which can be caused by bacteria such as Shigella , Campylobacter , and Salmonella. Pathogenic bacteria also cause infections such as tetanus , typhoid fever , diphtheria , syphilis , and leprosy. Pathogenic bacteria are also the cause of high infant mortality rates in developing countries. Koch's postulates are the standard to establish a causative relationship between a microbe and a disease.
They inhabit virtually every environment on the planet A pathogen is defined as an organism causing disease to microbial species is a human pathogen.
A Guide to Different Types of Pathogens
A pathogen may also be referred to as an infectious agent , or simply a germ. The term pathogen came into use in the s. However, these animals are usually, in common parlance, referred to as parasites rather than pathogens.
Pathogens are microscopic organisms that cause or have the potential to cause disease. While these pathogens cause a variety of illness ranging from minor to life-threatening, it is important to note that not all microbes are pathogenic. They only cause problems when they colonize locations in the body that are typically kept germ-free or when the immune system is compromised. In contrast, truly pathogenic organisms have a single goal: survive and multiply at all cost. Pathogens are specially adapted to infect a host, bypass the host's immune responses, reproduce within the host, and escape its host for transmission to another host.
These infectious microscopic organisms are known as pathogens, and they can multiply quickly. Examples of pathogens include:. They can spread in several different ways, including through:.
What You Need to Know About Pathogens and the Spread of Disease
Your body is naturally full of microbes. However, these microbes only cause a problem if your immune system is weakened or if they manage to enter a normally sterile part of your body. All a pathogen needs to thrive and survive is a host. Pathogens can be transmitted a few ways depending on the type. They can be spread through skin contact, bodily fluids, airborne particles, contact with feces, and touching a surface touched by an infected person. They then use the components of the host cell to replicate, producing more viruses.
For most infectious diseases, the ability to accurately identify the causative pathogen is a critical step in finding or prescribing effective treatments. Koch made several assumptions that we now know are untrue in many cases. The first relates to postulate 1, which assumes that pathogens are only found in diseased, not healthy, individuals. This is not true for many pathogens. For example, H.
A variety of microorganisms can cause disease. Pathogenic organisms are of five main types: viruses, bacteria, fungi, protozoa, and worms. Some common.
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