Final Exam Study Deck:) Flashcards
What percent of human pathogens are viruses and prions
15%
What percent of human pathogens are bacteria
40%
What percent of human pathogens are fungi
20%
What percent of human pathogens are Protozoa
5%
What percent of human pathogens are Helminths
20%
What are the important structural componets of fungi
Have cell walls made of chitin (no peptidoglycan or cellulose)
Have a cell membrane made of a phospholipid bilayer with sterols in them (ergosterol)
What are the 2 forms of fungi
Yeasts and molds
Yeasts are unicellular
Molds are multicellular
What are the formations that yeasts are found in
Pseudohyphae (short chains)
How to yeasts reproduce
by budding
What are molds made of
Hyphae- long Strings of cells
Septate hyphae have walls between cells
Aseptate hyphae have no walls between cells
What types of infections (generally) do molds cause in humans
Fungal infections
Which organism was the original source of penicillin
Mold
Dimorphic fungi change between which two forms
Between mold and yeasts- They are molds when convenient (i.e. in soil) and change to yeast in lungs (i.e. to infect someone!)
What is the route of transmission for protozoal infections
Waterborne, foodborn, contact with farm animals, mice, birds and their feces, swimming or bathing in contaminated water
What are protozoa classified as (multi or unicellular, eukaryotes or prokaryotes?)
Unicellular eukaryotes
What stages of life cycle do protozoa usually have
Usually trophozoite and cyst forms
Trophozoite is active, feeding and reproducing. Cysts are tough dormant forms iwth a wall.
How are cysts from protozoa usually shed
In feces during a GI infection of the person
What are the common routes of transmission for Helminth infections
Transmitted through feces in soil, fecal- oral routes (ingest eggs in soil), Eat undercooked pork containing tapeworm or larvae in cysts, or by mosquitoes
What are the common characteristics of helminths
Multicellular eukaryotes with organs
Have 3 forms: Egg, Larvae, Adult worms
What is the life cycle of ascaris lumbricoides? Include transmission, eggs, larvae, and adult worm stages
-Transmission is fecal-oral through eggs in soil that are ingested by waterborne or foodborne routes.
-Eggs hatch into larvae in intestines
-Larvae penetrate host blood vessels and migrate to alveoli of lungs
-Larvae are coughed up and swallowed back into intestines where they grow into adult worms
What are the 6 steps required for a pathogen to infect its host
Exposure
Transmission/Entry
Adhesion
Invasion
Infection
Evasion of the Host immune System
“Every Tiny Ant is in Euphoria”
- I would like to be a tiny ant, they don’t study much, so they’re euphoric.
What is the difference between an active and passive carrier of a pathogen
Active carriers are infected with the disease and can transmit it to others
Passive carriers are NOT “infected” but are asymptomatic and can carry the pathogen on their skin or in their blood to transmit to others.
Active Carriers are always symptomatic- true or false?
False- They can be symptomatic or asymptomatic
Describe contact transmission
There is indirect, direct, droplet, and congenital contact transmission. The infected person or their fluids go directly to the susceptible person (or via a surface, etc)
What are the 4 subtypes of contact transmission
Direct- Infected person to susceptible person
Indirect: Infected person to object to susceptible person
Droplet: Infected person to a droplet touched by a susceptible person
Congenital: Mother to fetus
What are the 3 subtypes of vehicle transmission
Airborne, Waterborne, Foodborne
What are the 2 subtypes of vector transmission
Mechanical:
Body or feet of an arthropod or insect to susceptible person
Biological:
Bite, vomit, or defecation of arthropod to susceptible person
What are portals of entry
Ways that the pathogen can enter the host
Describe the portal of entry that pathogens in the air can use
They can enter our respiratory tract through ventilation
Describe the portal of entry that pathogens in our food and water can use
They can enter via our GI tract through our intake of food or water
Pathogens in water that we bathe in can enter our skin if it is broken
Describe the portals of entry that pathogens on our skin can use to enter our body
They can enter the urinary tract or reproductive tract
What are some common mechanisms of adhension that pathogens use
Fimbriae, pili, capsules, slime layers, biofilms, hooks, barbs, and spike proteins are adhesins
What is an adhesin?
A protein or glycoprotein on the surface of a pathogen that helps adhere to receptors on the host cell
Describe Invasion as a step of pathogen infection
Spread of the pathogen through tissues or the whole body
Pathogens might secrete exoenzymes or toxins to help them invade
Describe infection as a step of pathogen infection
Exotoxins are produced (proteins that are secreted by bacteria that cause damage to host cells)
Gram negative bacteria release LPS when they die, which stimulates an immune response. Which step in pathogen infection does this fall into?
It falls into infection- the pathogen secretes exotoxins that cause damage to the host cells.
What are some of the ways that organisms can evade the host immune system?
Some pathogens can survive phagocytosis and reproduce in host cells
Phagocytosis of a pathogen creates a phagolysosome
Some bacteria can prevent
fusion of phagosome and lysosome
DNAse breaks down NETs (Neutrophil extracellular traps)
Some pathogens can survive inside host cells to evade immune system
What is virulance
The ability of an organism to cause infection and damage to its host
What are virulence factors
Help the pathogen progress through any stage of infectious disease and determine the severity of the disease that the pathogen can cause
What is virulence an indication of
How dangerous the infection is, but not how well the pathogen will survive
Our bodies/Host bodies creates secretions in the respiratory tract and they have cillia that help to remove pathogens. What is a pathogen’s strategy to overcome this host defence?
Pathogens have adhesins and have firm attachments to epithelium
In host bodies, cilia beat rythymically to push microorganisms and parasites out of the trachea. What is a pathogen’s strategy to overcome this host defence?
Pathogens inhibit movement of cilia- i.e. cause paralysis of epithelial cells, which causes mucus to accumulate in lungs
Host cell membranes are a barrier to pathogens. What is a pathogen’s strategy to overcome this host defense? What are 2 pathogens that commonly do this?
Pathogens can traverse host cell membranes. They have a fusion protein in a viral envelope (HIV or Influenza)
Host immune systems have a complement activation system. What is a pathogen’s strategy to overcome this host defense?
Pathogen can interfere with complement components and produce an enzyme (elastase)
Pathogens can interfere with complement mediated phagocytosis, they can block complement access (Candida albicans)
Host cells have an immune system. What is a pathogen’s strategy to overcome this host defense? What are 2 pathogens that have this mecahnism?
Microbe can destroy antibody, bacteria can produce IgA protease (streptococci, neisseria meningitidis)
Which action leads to the greatest shedding of respiratory droplets
Sneezing
How many UTIs are there in the USA per year
12.5 million
How many UTIs are there worldwide every year
125 million
Which pathogen type is the most common cause of a UTI
Bacteria
What is the single most common cause of a UTI
E. Coli
Is E. Coli primary or opportunistic when infecting people to cause a UTI?
Can be either primary or opportunistic
Are women or men at greater risk of UTI, and why?
Women are much more at risk (14 times as much) because of their short (2.5 inch long) distance from urethra to anus compared with men (around 7.5 inches)
What are the 3 ways that pregnancy increases the risk of getting a UTI?
- Pregnancy increases the amount of glucose and protein in the urine and women are at a higher risk of a UTI since bacteria can grow in it.
- Progesterone is also higher in pregnancy, which decreases smooth muscle tone in ureters
3.Uterus can block flow through urinary tract from ureters to urethra
Which 2 factors increase the risk of a UTI in men
Uncircumcision (idk if thats a word) and Catheters that are inserted
Also, people in nursing homes are at a higher risk
Which bacteria is a normal and important member of the female vaginal microbiome
Lactobacillus- They are in normal vaginal secretions
What does Lactobacillus do in the vagina? (What does it secrete? What does this do?)
Lactobacillus ferments glycogen in the vagina and produces an acidic lactic acid, which lowers the pH in the vagina so that other pathogens cannot infect it
What does the vagina have in its secretions normally that attracts Lactobacillus?
Glycogen– Lactobacillus uses this to ferment and create lactic acid, which in turn lowers the vagina’s pH
What is Bacterial Vaginosis
Infection of the Vagina
How is Bacterial Vaginosis transmitted
May be transmitted via sexual contact, but transmission is controversial
Bacterial vaginosis is associated with a decrease in which resident vaginal pathogen
Lactobacillus
Why does a decrease in lactobacillus in the vagina cause BV?
Less lactobacillus leads to an increased pH, so other pathogens can infect the vagina.
Which pathogens enter the vagina when lactobacillus concentration decreases?
Gardenella vaginalis (opportunistic pathogen) increases and causes a biofilm in the vaginal epithelial cells.
What are signs and symptoms of BV
Vaginal discharge, fishy odor, vulvar irritation, vulvar burning
Asymptomatic in 85% of women
What does BV increase the risk of
BV increases the risk of getting HIV, HSV, and Gonorrhea, Chlamydia
How do you diagnose BV?
Thin and homogenous vaginal discharge, Fishy odor, pH >4.5, Wet wipe shows clue cells (must have ¾ of these)
What is the treatment for BV?
Topical or oral metronidazole
What is the most common route of transmission for Bloodborne pathogens
Through arthropods like mosquitoes, lice, ticks, and fleas
What is usually an essential part of the life cycle for the pathogen?
A vector- the pathogen can then be infected into the host
Which parasite transmits malaria?
anopheles mosquito
Which pathogen spreads plague?
Rat fleas
Which pathogen spreads typhus?
Lice
What pathogen causes bubonic plague
Yersinia pestis bacteria
How is the bubonic plague transmitted
Through the bite and vomitting of the rat flea
Aside from through an arthropod, what are 4 other ways that blood born pathogens can spread?
- From mom to fetus in infections like HIV, CMV, Hep B, syphillis
- IV drug use can spread HIV, Hep B, etc
- Shared syringes that hospitals do not steralize properly
- Transfusions of contaminated blood
The virulance of a pathogen is directly correlated with its ability to be transmitted to other hosts. True or false
False!
The ability of a pathogen to be transmitted varies indipendently of the pathogen’s ability to do damage
What is the most effective route of transmission worldwide of pathogens?
From person to person (can be respiratory, fecal-oral, or sexual)
Called Contact transmission
What are the 3 factors that determine if the transmission of a pathogen is successful or not
- The number of pathogens shed
- The stability of the pathogen in the environment
- The number of pathogens needed to infect the new host
Describe how the number of pathogens shed is tied into transmission from the pathogen to the host
The more bacteria or pathogens that are shed, the greater the chance of reaching a new host
Most shed organisms die
Describe how the stability of the pathogen in the environment is tied into transmission from the pathogen to the host
The ability to withstand dehydration and extremes of temperature are the major factors predicting the success of pathogen transmission
Microorganisms that resist drying spread more rapidly than those sensitive to drying
Describe how The number of pathogens needed to infect the new host is tied into transmission from the pathogen to the host
The number of pathogens needed to cause an infection is variable between pathogens (i.e. it only takes 10 shigella bacteria, but need 1x10^6 salmonella to cause food poisioning)
The tissue of the host that the pathogen is infecting matters (i.e. you only need 10 neisseria gonorrhoeae to cause a urethral infection, but thousands are needed to cause an infection in the rectum)
How do the host activities change the efficiency of transmission for a pathogen?
Sneezing and coughing benefit the pathogen
How do pathogens increase the activities of a host to benifit them in their transmission?
Sneezing and coughing benefit the pathogen
Pathogen strains that increase fluid secretions or irritate epithelium induce more coughing and sneezing, so are transmitted more effectively
GI pathogens that increase GI secretions or diarrhea spread more effectively
What is the primary factor that kills pathogens after they are shed from their host
Dehydration
Pathogens that are dehydrated are (MORE OR LESS) resistant to thermal inactivation?
More resistant- less water to freeze inside of them
Are pathogens infectious for a longer or shorter time if they are resistant to thermal inactivation
They are infectious for a longer period of time if they are resistant to thermal inactivation
How is sexual transmission of pathogens controlled
Difficult to control- education and access to protection
How are respiratory transmission routes controlled
difficult to control- education and masks
How is fecal-oral transmission controlled in pathogens?
Hand washing and public health measures
How are Arthropod-borne infections and zoonoses controlled for transmission?
can be controlled by controlling vectors and animal infection
What are the characteristics of Dermatophytes
MOLDS
Dermatophytes infect skin, nails, and hair.
Live in moist, dark areas
Diagnosed with PE, KOH or UV for fluorescence
What are some of the diseases caused by Dermatophytes
Cutaneous fungal infections of the skin are usually called tinea or mycoses
Tinea cruris- Jock itch
Tinea pedis- Athlete’s foot
Tinea Unguium- Nails
What is the transmission of Dermatophytes caused by
Contact with the pathogen
How are Dermatophytes’ infections treated
With Azoles
Characteristics of E. Coli
Gram - bacteria (cause LPS release if not careful when dying)
What are the diseases caused by E. Coli infection
UTIs, Diarrhoeal diseases, neonatal meningitis, Sepsis
Are E. Coli usually found in humans? If so, Where?
Yes- normal part of the gut of humans
What are 2 of the pathogeneses associated with E. Coli
Endotoxins and adhesions that are associated with UTIs
Enterobacteriacae Characteristics (And common types)
Most numerous facultative anaerobes in the human gut-
E. Coli, Klebsiella, Enterobacter, Salmonella, Shigella, Citrobacter, etc.
Characteristics of Clostridium difficil
Forms Spores
Can be part of normal microbiome
Often arises from long term antibiotic use that lets C diff overgrow
Diseases associated with C. Diff
Colitis
Colon infection (Fever, dehydration, watery diarrhea)
Treatment: Stop taking antibiotics, start vancomycin
Transmission of C. Diff
Normally found in gut flora, flourishes under antibiotic use
Can be transmitted via fecal-oral route
Pathogenesis of C. Diff
Produces Enterotoxin and cytotoxin
What are common diseases caused by Genus Clostridium
C. Difficile
Botulinum
Teatnus
Gas Gangrene
How do Botulinum toxin and Teatnus toxin infect the host
C. Botulinum makes Botulinum toxin and C. Tetani makes tetanus toxin- both are intracellular targeting toxins
What is the most common cause of death due to an infection in the world
TB
signs and symptoms of a Mycobacterium TB infection
Signs and symptoms are a bloody cough, weight loss, fever, ches pain.
Common Transmission for TB
Transmission from fine respiratory droplets
Coughing, Sneezing, Airborne transmission
Pathology of TB
In Alveoli, TB engulfed by Macrophages. TB prevent fusion of phagosome and lysosome
TB grows in the alveoli, escapes in the lungs and forms granulomas (ruptured alveoli)
Escapes the lungs and is spread
Genus mycobacterium characteristics
Widespread in the environment and in animals.
Tuberculosis and Leprosy are present in humans
More dangerous for people who are immunocompromised
What is the transmission of Plasmodium
Vector transmission with Anopheles mosquitoes
Trichomonas Vaginalis Characteristics and Fun facts
Causes Trichomoniasis STD
Flagellate living normally in urinary system of females and males
Trophozoite form only- NO cyst
Sexually Transmitted
Treated with Metronidazole (Toxic DNA metabolites)
Plasmodium characteristics
Protozoa
Live in Liver and RBCs
Diseases caused by Plasmodium
Malaria
Caused by P falciparum (most common and most dangerous)
Pathogenesis of Plasmodium
Liver and blood stages: sporozoites enter the liver and develop into merozoites, which then infect red blood cells (RBCs), causing cyclic fevers.
- MALERIA
Ascarias Lumbricoides pathogenesis
Larvae cause pneumonitis, adults can obstruct digestion and absorption of food, can migrate to pancreatic or bile ducts. See other specifics about coughing/Swallowing
Ascarias lumbricoides characteristics
Large Roundworms (Helminth)
Most common in tropical countries
Infection caused by ascarias lumbricoidses
Ascariasis
Transmission of Ascarias lumbricoides
Swallowing infective eggs in contaminated soil, food, or water
What types of a pathogen are genus pseudomonas pathogens
Opportunistic pathogens
Genus vibrio Characteristics
V. Cholerae is most important
Highly motile, capable of anaerobic respiration
Can cause Cholera
No animal Reservoire
Has Mucinase, adhesions, enterotoxins
Characteristics of V. Cholerae
Highly motile, capable of anaerobic respiration
Has mucinase, adhesions, enterotoxins
Diseases caused by V. Cholerae
Cholerae
Cause extreme amounts of fluid loss, very dangerous
How is V. Cholerae acquired
Acquired via contaiminated water or food
What is the pathogenesis of V. Cholerae
Produces mucinase, adhesions, enterotoxin.
Binds to intestinal epithelial cells, causes fluid loss and diarrhea
Pseudomonas aerginuosa characteristics
Part of normal gut flora, Opportuniistic in hospitalized patients
Aerobic and gram negative
Has endotoxins, capsule
Diseases caused by Pseudomonas aerginuosa
Cystic fibrosis
UTI
Endocarditis, septicemia
osteomyelitis
Transmission of Pseudomonas Aerguinosa
Contact: direct or indirect
Pathogenesis of Pseudomonas Aerguinosa
Opportunistic. Common in moist environments,
Is E. Coli Aerobic or anaerobic
Anaerobe
Trichomonas vaginalis transmission
Sexually transmitted- Venereal
What does tricohomonas vaginalis cause in females
vaginitis with discharge
What are the 3 main resistance mecahnisms of bacteria
A change in the target of the antimicrobial
A decrease in the uptake of the antimicrobial
Development of enzymes that inactivate the antimicrobial
What is antibiotic resistance spread by most commonly
Horizontal gene transfer from plasmid transfer between bacteria
Where does Mycobacterium TB live in the body (SPECIFICALLY) when infecting hosts?
In a macrophage
What type of pathogen is pneumocystic jirovecii?
Fungi
How is entamoeba histolytica, the cause of amoebic dysentery, transmitted from one person to the next?
Fecal-oral contaminated food and water
Plasmodium falciparum is the most common cause of malaria in tropical and subtropical regions. What human cells does plasmodium target?
Hepatocytes and RBC
What aquatic organism is an essential intermediate in the life cycle of schistosoma blood flukes?
Snails
Taeniasis is a disease caused by ingestion of taenia solium cysts in what type of food
Undercooked pork
Identify one common disease caused by one of the dermatophytes, Epidermophyton, Microsporum, and Trichophyton
Tinea pedia, tinea corporis, tinea capitis
Which population is most susceptible to aspergillosis?
People who are immunocompromized
Fungal cell walls are made of ___, which is one of many factors that make them difficult to phagocytose
Chitin
Human cell membranes rely on cholesterol for stability. Fungal membranes have a similar molecule called ___, which is the target of many of our anti-fungal drugs
Ergosterol
Which anatomical location is not generally a common target of protozoa?
Lungs
Identify one common route of transmission for protozoal infections
Fecal-oral
Which of the following is NOT a likely route of transmission of a helmnith?
Inhalation of aerolosized droplets containing eggs or larvae
Briefly describe one contributing factor to the tropical distribution of helminths
Tropical distribution depends on: wet/humid/moist environments and potential interim hosts (eg. snails), typically in poorer countries with less hygiene
How large can the roundword Ascaris lumbricoides grow in the human intestinal tract?
30 Cm
What human cell do mycobacterium tuberculosis, an intracelluar pathogen, infect and survive in?
Macrophages
How is mycobacterium usually transmitted?
Airborne droplets
What disease does C. Botulinum cause and how
Flaccid or limp paralysis
What disease does C. Tetani cause
Teatnus- Spastic, rigid paralysis
What disease does C. Perfringens cause
Gas Gangrene
What disease does C. Difficile cause
Diarrhea, often associated with long term antibiotic use
Which characteristics are common to all members of the genis clostridium?
Anaerobic, Gram positive, Spore-forming, Bacillus
Which of the following steps is not required for a successful infection?
Cause host damage
Attachment
Multiplication
Evade host defenses
Exit
Cause Host Damage
What are some ways that pathogens gain entry into hosts?
Through breaks in the skin, damaged mucosal membranes, insect/animal bites
True or false: The greater the virulence of a pathogen, the more likely it is to be successful
False
Identify the host defense that HIV and Influenza have a counter defense against
Host defense: Mechanical barrier (cell membrane)
Microbe adaptation: Fusion proteins in viral envelope allow it to traverse the membrane
True or false: For a given pathogen, the disease is the same for all people
False- The disease is NOT the same for all people
some have stronger or weaker responses
Approxamately how many species of pathogenic microbes are there?
1500
Which member of the vaginal microbiome ferments glycogen, produces lactic acid, lowers the pH of the vagina and protects the vagina from many pathogens?
Lactobacillus
Which activity leads to the greatest shedding of respiratory droplets
Sneezing
Why are UTIs more common in women than in men?
Women have a shorter urethra; the female urethra is close to the anus than that of the male
What is the most common route of transmission of bloodborne pathogens
Biting Arthropods
Does the length of time a pathogen has been in the first host impact the success of pathogen transmission?
No- The number of microbes shed by the first host, the stability of the pathogen in the environment, and the number of pathogens needed to infect the host are what matter
Most pathogens that are shed from a human host into the environment die. What is the primary factor that causes death?
Dehydration
Which antibiotic inserts and disrupts the cell membrane?
Lipopeptides and polymyxins
What types of organisms does TMP SMX treat
Bacteria, fungi, protozoa. Inhibits folic acid synthesis needed to make DNA. Inhibits metabolic pathways
Which antibiotic prevents topoisomerases and gyrases from seperating replication strands in DNA synthesis
Quinolones (Ciprofloxacin, levofloxacin)
Which antibiotic treats clostridium and Trichamonoas vaginalis?
Nitroimidazole- metronidazole (treats protozoa and bacteria)
Which antibiotic inhibits RNA synthesis, binding to RNA polymerase? What infection does this target?
Rifamycins- rifampicin
- TB treatment
Which antibiotics inhibit the 30s subunit for protein synthesis?
Tetracyclines, aminoglycosides
Which antibiotic inhibits DD bridge linking?
Beta- lactams–> Penicillins (amoxycycline) and cephlasporin, which inhibit cell wall synthesis
Which antibiotics bind to terminal D alanine at end of the bridge so that no new bridges can form?
Glycopeptides– Vancomycin (Cell wall synthesis inhibition)
Which antibiotic kills bacteria by creating toxic metabolites which causes DNA to be fragmented?
Nitroimadazoles (metronidazole)
- Inhibit nucleic acid synthesis or Damages DNA (this one damages DNA)
