Flashcards
Microbiology Exam Three Chapters 14, 15, 16, 17, and 18
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- 1Discuss the development of normal flora in humans.Normal flora in humans is a symbiotic relationship. Most resident microbes are established during the first few months of life. Rupture of the amniotic sac and passage through the birth canal and the first few breaths allowed microorganisms to enter through the mouth and nose and establish residence in the respiratory tract. The first meals allowed progenitors of microbiota to set up residence in the colon. Skin contact also allowed the transfer of microorganisms to the infant's skin.
- 2The ubiquitous flora is not always protective to humans. Discuss a few ways in which the flora can become opportunistic pathogens.Introduced to a new area of the body
if the immune system is suppressed - stress, disease, malnutrition, age, chemotherapy, radiation, or immunosuppression drugs
Changes in normal flora - this happens when there is a decline in lactobacillus that allows gardenrella to multiple - another example: when antibiotics affect the normal bacteria int he vagina allowing Candida albicans to grow - 3Describe three types of reservoirs using examples1. Animal reservoir - infectious diseases live in animals and can be transmitted to humans by direct contact with infected animals or their wastes, eating infected animals, or through blood sucking arthropods who fed off of infected animals that then bit a human. Once human is infected, the zoonose is a dead-end diseases.
Ex: Malaria: transmitted from a mosquito that fed off of a monkey
Ex: Lyme disease which is transmitted from a tick who has fed off of a deer
2. Human carrier - someone asymptomatic or healthy due to defensive system and unknowingly transmits pathogen to others.
Ex: Mary Mallon - asymptomatic carrier of typhoid in the 1900s - chef who transmitted through food
Ex: HIV virus - infected person doesn't know for first three months. Period of time allows a carrier to spread the disease unknowingly to others
3. Nonliving reservoir: soil, water and food that has been contaminated. Soil contaminated with feces can harbor Clostridium pathogens. Water contaminated with fecal mater and urine may contain parasitic worm eggs, protozoa, bacteria, and viruses - 4Compare and contrast the following terms: infection, disease, morbidity, pathogenicity and virulence.Infection: when an organism enters the body , multiplies, and establishes itself in the body. An infection may or may not result in a disease.
Disease: any internal condition in the body that is severe enough to interfere with normal function
Morbidity: another term for disease which is any change from a normal state of functioning.
Pathogenicity: a microbe's ability to cause disease
Virulence: the degree of pathogenicity, the ability of a pathogen to infect a host and cause a disease
If the pathogenicity of an organism is high, then there are virulence factors. Virulence factors means the pathogen in more virulent. The more virulent the pathogen, the higher the morbidity. - 5Infectionwhen an organism enters the body, multiples, and establishes itself in the body
May or may not result in a disease - 6Diseaseany internal condition in the body that is severe enough to interfere with normal function
- 7Morbidityanother term for disease which is any change from a normal state of functioning
- 8Pathogenicitya microbe's ability to cause disease
- 9Virulencethe degree of pathogenicity, the ability of a pathogen to infect a host and cause a disease
- 10Virulence factorsPresent when pathogenicity is high
Means the pathogen is more virulent
the more virulent the pathogen, the higher the morbidity - 11What is the difference between signs and symptoms? Provide three examples of each.Signs: manifestations of a disease that can be observed or measured
Ex: fever, blood pressure, pulse, liver enzymes
Symptoms: manifestations of a disease that are subjective (can not be measured)
Ex: fatigue, pain, or nausea - 12Compare and contrast exotoxins and endotoxins. Use examples.Endotoxins come from a gram- bacterium. The lipid A lipopolysaccharide is anchored to the outer membrane. When the bacterium dies, the lipid A is released. In large enough numbers, the endotoxin effects are damaging. It can send a person into shock which can lower blood pressure.
Ex: Haemophilus influenza, pseudomonas, and Vibrio cholerae.
Exotoxins are from gram+ and gram- bacteria. They are secreted by microorganisms and either kill the host cell or interrupt the metabolism of the host cell.
3 types of exotoxins: cytotoxins, neurotoxins, and enterotoxins.
Cytoxoxins kill the host or interrupt the metabolism.
Neurotoxins interfere with nerve cell function.
Enterotoxins affect the lining of the gastrointestinal tract.
Ex: Clostridia, E. coli, Shigella - 13Describe the mechanism by which capsules enhance the survival of pathogens.Capsules are made of many chemicals found in the human body such as polysaccharides. For this reason, capsules do not stimulate a response from the host. Additionally, many capsules are slippery which makes it hard for phagocytes to surround them.
- 14Contact transmissionIt is the spread of pathogens from one person to another by three methods: direct contact, indirect contact, and droplets.
Direct contact requires body contact between one host and another.
Ex: ringworm, sexually transmitted diseases, rabies
Indirect contact is when fomites spread the disease from one host to another.
Ex: HIB and hepatitis B
Droplet transmission is when a pathogen is spread from one host to another through droplets of mucus. This can happen during coughing and sneezing.
Ex: cold and flu viruses - 15Vehicle transmissionIt is the transmission of pathogens through air, water, or food.
Hantavirus and Streptococcus can be found on dust particles that float through the air.
Amebic dysentery and cholera can be spread through water.
Food that is incorrectly processed, undercooked, or improperly stored can contain botulism and E. coli. - 16Vector transmissionVector transmission happens when a pathogen is spread in animals from one host to another.
Biological vectors such as mosquitos and ticks can pass pathogens from an infected animal to a human.
Examples: Malaria which is spread from an infected monkey which is fed on by a mosquito that later bit a human.
Lyme disease which is spread from a deer which is fed on by a tick that later bit a human.
Mechanical vectors are when pathogens are passively carried to new hosts via parts of the body such as the feet.
Ex: Houseflies and cockroaches which may introduce pathogens such as Shigella and Salmonella into drinking water, food, or directly onto skin. - 17Contrast droplet transmission and airborne transmission. How do we prevent transmission of pathogens by these methods?Droplet transmission: when a pathogen is carried on a mucous droplet through the air no more than one meter
Airborne transmission: the spread of a pathogen greater than one meter.
This can be caused by sneezing, coughing, air conditioners, sweeping, mopping, or even changing household linens.
This can mostly be prevented by commonsense such as sneezing or coughing into your elbow instead of your hand, not making big sweeping motions when sweeping or mopping, and not flapping linens around when taking them off the bed. - 18EndemicWhen the incidence and prevalence of a disease is stable
- 19EpidemicWhen the incidence of a disease is greatly increased, therefore, making the prevalence of a disease increase
- 20PandemicWhen the disease has spread across continents
- 21There are several types of nosocomial infections, ie endogenous, iatrogenic, superinfections. How are they different? Examples.Endogenic is when the normal flora of a person is introduced to a new area of the body in a hospital setting and becomes opportunistic.
Ex: when normal flora from a person's gut is introduced into the urinary system
Iatrogenic is when a pathogen is introduced through a medical procedure such as the insertion of a catheter.
Superinfections result from the use of antimicrobial drugs that inhibit normal flora to grow. This allows other flora to grow unchecked since there is no competition.
Ex: antimicrobial therapy may allow C. difficile to grow unchecked and cause pseudomembranous colitis. - 22Symbiosis meansto live together
- 23Types of symbiosisMutualism
Commensalism
Parasitism - 24MutualismBoth benefit
Ex: E. coli in gut/makes vitamins/host absorbs
Ex: use of probiotics - 25CommensalismOne causes no harm, other may benefit
Ex: S. epidermidis on skin/protects against pathogenic microbes - 26ParasitismAnything that acts like a pathogen
Ex: pathogens - 27Normal Microbiota in HostsAlso termed normal flora and indigenous microbiota
Can be affected by diet, medication, hormones
Not identical between people - 28Two types of normal microbiota in hostsResident
Transient - 29Resident microbiota definitionpermanent
part of you
can't sterilize yourself - 30Transient microbiota definitionThings that you pick up
hospital, daycare, school, work, environment - 31axenicno natural microbiota
Ex: alveoli - 32Upper Respiratory tract Resident MicrobiotaHaemophilus, Lactobacillus, Moraxella, Staphylococcus, Fusobacterium
- 33Upper digestive tract Resident microbiotaActnomyces, Bacteroides, Haemophilus, Staphylococcus, Lactobacilllus, Neisseria
- 34Lower digestive tract resident microbiotaBacteroides, Clostridum, Enterococcus, Escherichia, Fusobacterium, Lactobacillus, Proteus, Shagilla
- 35Female Urinary and Reproductive Systems Resident MicrobiotaBacteroides, Clostridium, Lactobacillus, Staphylococcus, Streptococcus, Candida
- 36Male Urinary and Reproductive Systems Resident MicrobiotaBacteroides, Fusobacterium, Lactobacillus, Mycobacterium, Staphylococus, Streptococcus
- 37Eyes and Skin Resident MicrobiotaCorynebacterium, Micrococcus, Propionibacterium, Staphylococcus, Candida, Malassezia
- 38Transient microbiotaRemains in the body for a short period
Found in the same regions as resident microbiota
Cannot persist in the body (competition from other microorganisms, elimination by the body's defense cells, chemical or physical changes in the body) - 39Acquisition of normal microbiotadevelops first few months of life
as they go through stages - how they mold and shape their flora
all it takes is to be exposed to air
development in womb free of microorganisms - axenic
Microbiota begin to develop during the birthing process
Much of one's resident microbiota established during first months of life - 40opportunistic pathogensnormal microbiota that cause disease under certain circumstances
UTI, pneumonea - 41Conditions that provide opportunities for pathogensIntroduction of normal flora into a different site
Immune suppression
Changes in normal flora - 42Reservoirs (source) of infectious disease of humansmost pathogens cannot survive for long outside their host
reservoirs (vectors) of infection: sites where pathogens are maintained as a source of infection - 433 types of reservoirs (vectors)Animal reservoir
Human reservoir
Nonliving reservoir - 44Animal reservoirsZoonoses (dead-end diseases): diseases naturally spread from animal host to humans
Aquired zoonoses through various routes: direct contact with animal or its waste, eating animals, bloodsucking arthropods
Humans are usually dead-end host to zoonotic pathogens - 45Reservoirs of Zoonoses in Humans caused by ProtozoaEx: Malaria (Plasmodium) - monkey/bite of anopheles mosquito
Toxoplasmosis (Toxoplasma gondii) - cats/ingestion.inhalation of pathogen and contact - 46Reservoirs of Zoonoses in Humans causes by FungiEx: Ringworm (Trichophyton) - Domestic animals/direct contact
- 47Reservoirs of Zoonoses in Humans caused by BacteriaEx: Anthrax (Bacillus anthracis) - livestock
Lyme Disease (Borrelia burgdorferi) - Deer/tick bite
Salmonellosis (Salmonella) - Birds, rodents, reptiles, eating fecally contaminated foods - 48Reservoirs of Zoonoses in Humans caused by VirusesEx: Rabies (Lyssa virus) - Bats, foxes, skunks, dogs/bite
Hantavirus pulmonary syndrome (Hanta virus) - Mice/inhalation of dried urine and feces
Yellow Fever (Flavivirus) - Monkeys/bite of Aedus mosquito - 49Human Carriers Reservoirs of Infectious Disease of HumansAsymptomatic
Ex: HIV, STDs, Herpes, hepatitis B
Infected individuals who are asymptomatic but infective to others
Some individuals eventually develop illness while others never get sick
Healthy carriers may have defensive systems that protect them
They can transmit to someone else who might get sick - 50Nonliving Reservoirs Reservoirs of Infectious Disease of HumansSoil, water, and food can be reservoirs of infection
Soil (fungal, helminthic and bacterial pathogens) may contain fecal matter
Water can be contaminated with fecal matter and urine (may harbor parasitic worm eggs, pathogenic protozoan, bacteria, and viruses)
Food - 51What does helminthic mean?worms
- 52Exposure to Microbes: Contamination and InfectionContamination: the mere presence of microbes in or on the body
Infection: when organism evades body's external defenses, multiplies, and becomes established in the body
Can be contaminated but not sick - 53Portals of EntrySites through which pathogens enter the body
Four major pathways:
Skin, Mucous membranes, Placenta
Parenteral route (injected in - malaria, Lyme disease) - 54Portals of entry equalportals of exit
May leave same route or take new route - 55Mucous membranes Portals of EntryLine the body cavities that are open to the environment
Provide a moist, warm environment hospitable to pathogens
Entry is through the nose, mouth, or eyes
Gastrointestinal tract may be route of entry - must survive the acidic pH of the stomach - 56Placenta Portals of EntryTORCH
(Toxoplasmosis, Other - chicken pox, measles, Rubella, Cytomegalovirus, Herpes)
Typically forms effective barrier to pathogens
Pathogens may cross the placenta and infect the fetus
Can cause spontaneous abortion, birth defects, premature birth - 57Parenteral Route Portal of EntryNot a true portal of entry
Pathogens deposited directly into tissues beneath the skin or mucous membranes - 58So how do organisms attach once they get in?Adhesion
- 59AdhesionProcess by which microorganisms attach themselves to cells
Required to successfully establish colonies within the host
Adhesion factors
The specific interaction of adhesions/receptors determines the specificity of pathogens for particular hosts - 60Adhesion factorsFimbriae, glycocalyx
Able/more successful in causing infection
(Specialized structures, attachment proteins) - 61Nature of infectious diseaseInfection is the invasion of the host by a pathogen
Disease results if the invading pathogen alters
Disease is also referred to as morbidity - 62Mortality vs MorbidityMortality - death
Morbidity - illness - 63SymptomsManifestations that are subjective
Ex: pain, fatigue, chills, stomach ache, lethargy, headache, malaise, itching, abdominal cramps - 64SignsManifestations that are measured or observed
Ex: fever, BP, O2 stat, pulse, blood sugar, liver enzymes, rash, pus formation, anemia - 65SyndromeSymptoms and signs that characterize a disease or abnormal condition
Ex: AIDS, Metabolic syndrome, Down syndrome - 66Asymptomaticsubclinical
infections lack symptoms but may still have signs of infection - 67What is virulence?How pathogenic an organism is
degree of pathogenicity
slightly pathogenic, highly pathogenic, etc. - 68Pathogenicityability of a microorganism to cause disease
- 69Virulence factors contribute topathogenicity
*Adhesion factors, biofilms, extracellular enzymes, toxins, antiphagocytic factors (glycocalyxes, capsule, etc.)
The more virulence factors - the more virulent
The more virulent - the more morbidity - 70More virulent to less virulentFrancisella tularensis (rabit fever)
Yersinia pestis (plague)
Bordetella pertussis (whooping cough)
Pseudomonas aeruginosa (infection of burns - not an outright pathogen, opportunistic)
Clostridium difficile (antibiotic-induced colitis)
Candida albicans (vaginitis, thrush)
Lactobacilli, diptheroids - 71Extracellular EnzymesInvasive bacteria reach epithelial surface - bacteria produce hyaluronidase and collagenase - bacteria invade deeper tissues
Bacteria produce coagulase (formation of clots from fibrinogen - takes fibrinogen and turns it into fibrin) - bacteria later produce kinsase (dissolving of a clot that allows microorganism to break free) - 72Coagulase positive microorganismStaphylococcus aureus
- 73ToxinsChemicals that harm tissues or trigger host immune responses that cause damage
Toxemia refers to toxins in the blood stream that are carried beyond the site of infection
Exotoxins - released from inside of cell to outside of cell - 74Majority of gut flora isgram negative
- 75If there was a vaccine for gram- bacteria, we would....we would most likely be desensitized to it due to the majority of the flora in our gut is gram negative
- 76ExotoxinsSource: both gram- and gram+
Chemical nature: protein or short peptide
Relation to bacteria: metabolic product secreted from living cell
Toxicity: High
Heat Stability: Typically unstable at temperatures above 60 degrees
Effect on host: Variable depending on source; may be cytotoxin, neurotoxin, enterotoxin
Fever producing: no
Antigenicity: Strong: stimulates antitoxin (antibody) production
Toxoid formation for immunization?: By treatment with heat or formaldehyde
Representative diseases: Botulism, tetanus, gas gangrene, diphtheria, cholera, plague, staphylococcal food poisoning
Highly toxic (nano quantities) - 77EndotoxinsSource: gram-
Chemical nature: lipid portion of lipopolysaccharide (lipid A) of outer (cell wall) membrane
Heat stability: can autoclave for 1 hour till dead (121 degree Celsius)
Relation to bacteria: Portion of outer (cell wall) membrane released upon cell death
Toxicity: Low, but may be fatal in high doses
Effect on host: Fever, lethargy, malaise, shock, blood coagulation
Fever producing: yes
Antigenicity: Weak
Toxoid formation for immunization?: Not feasible
Representative diseases: Typhoid fever, tularemia, endotoxic shock, urinary tract infections, meningococcal meningitis
Low toxicity - takes a whole lot to kill - 78Antigenicityability of the host to see something as foreign
- 79Antiphagocytic factorsFactors prevent phagocytosis
Bacterial capsule: 1. composed of chemicals not recognized as foreign;
2. slippery
Antiphagocytic chemicals: 1. Ability to prevent fusion of lysosome and phagosome - phagocyte engulfs organism - lysosome fuses with an organism and digests it (ex: Neisseria gonorrhea, Legionella pneumophilia);
2. Production of factors that directly destroy phagocytes (Leukocidins/ Staphylococcus aureus)
3. Production of factors that resist phagocytosis (M protein/fimbriae of Streptococcus pyogenes)
Phagocytic cell can not wrap arms around M protein - 80The stages of infectious diseaseThe disease process occurs following infection
Many infectious diseases have five stages following infection - 815 stages of infectious disease following infection1. Incubation period - (hours, days to 3 months) organism gets into body - no symptoms
Ex: staphylococcus - potato salad - 4 hrs
HIV - 3 months
2. Prodromal period - When you first notice you are getting sick
3. Illness - when you say yea, I knew I was getting sick - here it is.
4. Decline
5. Convalescence - 82Incubation Periods of Selected Infectious DiseasesStaphylococcus foodborne infection: 4-6 hours
Influenza: About 1 day
Cholera: 2 to 3 days
Genital herpes: About 5 days
Tetanus: 5 to 15 days
Syphilis: 10 to 21 days
Hepatitis B: 70 to 100 days
AIDS: 1 to >8 years
Leprosy: 10 to >20 years - 83Portals of ExitPathogens leave host through portals of exit
Many portals of exit are the same as portals of entry
Pathogens often leave hosts in material the body secretes or excretes - 84—
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- Flashcards on Microbiology Exam Three Chapters 14, 15, 16, 17, and 18, created by Michelle Kimble on 30/03/2017.
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