Micro: Test 3

What is the difference between the epidermis and the dermis?

\-epidermis is stratified squamous epithelium. does not have a blood supply.

\
\-dermis is connective tissue. This is vascularized.

What is the difference between impetigo, cellulitis and gas gangrene?

What are the types of true skin infection?

\-Acne: follicle-associated lesions. Caused when pores are clogged by sebaceous gland secretions and dead cells

\-Impetigo: superficial bacterial infection causing the skin to flake (only epidermal)

\-Cellulitis: fast-spreading bacterial or fungal infection of the dermis and subcutaneous tissues (pain, swelling, warmth, fever)

\-Warts: viral infections which result in growths on the skin.

\-Gas gangrene: a specific type of cellulitis. Serious skin infection caused by Gram-positive endospore-forming bacteria.

\-Ringworm: fungal infections of the nonliving epidermal tissue (stratum corneum)

\-Skin mycoses: fungal infections of the skin at various layers

\*mycoses just means fungal infection\*

Where do staphylococci normally inhabit?

the skin and mucous membranes

(they are G+, lack spores, and are non-motile, may have capsules)

What virulence factors does S. aureus contain?

\-coagulase. (coagulates blood)

\-lipases

\-penicillinase (95% of staph aureus’s are resistant)

\-leukocidins

\-Exfoliative toxin (scalded skin syndrome)

\-toxic shock syndrome toxin (drop in blood pressure)

What types of localized and systemic diseases does S. aureus cause?

\-Localized: folliculitis, furuncle (boil), carbuncle (multiple boils together), impetigo. Presents as an abscess.

\-Systemic: osteomyelitis, pneumonia (low proportion, high fatality), bacteremia (endocarditis, arthritis, meningitis)

\*Usually invades the skin through wounds, follicles, or sweat glands\*

Do other species of S. aureus cause disease?

yes

How do you differentiate S. aureus from other staphs?

a coagulase test

What is the Staph-Ident System?

Series of biochemical tests in really small form. You look at the results, find a number, and look it up in a book to identify.

(can differentiate 19 different types)

What antibiotic are many staph strains resistant to?

penicillin

What is MRSA?

(Methicillin-Resistant S. Aureus)

\-a strain of staph aureus that is antibiotic resistant

\-vancomycin is the only treatment we have, but resistant strains are popping up over the last decade.

What bacteria genus is responsible for gas gangrene?

Clostridium

What type of environment must be present for this bacteria to grow?

Damaged tissue which supplies growth factors and an anaerobic environment (lack of blood flow)

How is gas gangrene treated?

\-cleaning and repair of wounds

\-debridement

\-cephalosporin or penicillin treatment

\-hyperbaric oxygen therapy

What virus has been eradicated from the earth through vaccination?

smallpox (1978)

Do other pox viruses (besides small pox) infect humans?

yes. cowpox, monkeypox, molluscipoxvirus.

What system does roseola affect?

integumentary

What virus causes chickenpox and shingles?

Varicella zoster-(it is herpes, not a pox!)

When is chickenpox most contagious?

2 days days before the rash. you’re no longer contagious after the blisters encrust.

What is the shingles?

When chickenpox resurfaces. Usually happens over the age of 60 (you’re more likely to be immunocompromised). Also most likely to be in the thoracic region or nerves.

What disease in humans is caused by a parvovirus?

“fifth disease” which is a mild rash that usually affects children

What are the typical symptoms of the measles?

\-full body rash

\-oral lesions. Red dots, in the middle, there are white or blue dots.

\-fever

\-serious secondary infections are also common

Why is a measles infection so serious?

\-The ID is so low

\-it is really aggressive

\-serious secondary infection is common

What vaccine is given for the measles?

MMR (measles, mumps, rubella)

(can’t give to children younger than 1 y.o.)

Which is generally more serious the measles or the German measles?

normal measles (unless you’re a fetus)

Why is it imperative that pregnant women don’t acquire the German measles?

(rubella) Congenital rubella syndrome: 15% of children with this syndrome die within the first year.

\-First trimester: miscarriage or serious neurological defects (deafness, blindness, etc.)

What is the insect vector for Leishmania?

phlebotomine flies (sand fly)

Where is Leishmania endemic?

equatorial regions (88 countries)

What forms does fungi exist in? What form is usually present in infections?

True and opportunistic pathogens. Most are opportunistic.

What is the difference between a true fungal pathogen and an opportunistic fungal pathogen?

True pathogens can infect normal people, opportunistic pathogens infect immunocompromised people

What characteristic do most fungal pathogens have which allow them to be pathogenic?

True pathogens:

systemic mycoses

subcutaneous mycoses

cutaneous mycoses (stratum basal)

superficial mycoses (stratum corneum)

Generally how do fungal infections occur?

Cutaneous:

\-hair and nails

\-usually known as ringworm (classified by region of the body you have it)

\-long incubation periods

Superficial:

\-usually don’t cause major problems or major inflammatory response

\-it can interfere with the melanocytes’ ability to produce melanin (patchy skin color)

What are the five fungi groups?

What are the five clinical fungal classifications?

1. chytridiomycota
2. zygomycota
3. ascomycota
4. basidiomycota
5. glomeromycota

Why are fungal diseases restricted to endemic regions?

they have specific habitat requirements

What are the types of subcutaneous mycosis?

1. sporotrichosis
2. chromoblastomycosis
3. phaeohyphomycosis
4. mycetoma

\-Transferred directly to traumatized skin.

\-Involves tissues within and below the skin.

\- Rarely spread bc they are inhibited by the temperature of blood

What type of mycosis does tinea/ringworm cause?

cutaneous

What is the difference between conjunctivitis and keratitis?

\-Conjuntivitis (pink eye): infection of the conjunctiva (covers all the white part of your eye)

\-Keratitis: infection of deeper layers of the cornea.

What makes up the CNS? The PNS?

CNS: brain and spinal cord

PNS: nerves emanating from the brain and spinal cord

How is the CNS protected from infection?

\-BBB (blood-brain barrier)

\-Meninges (dura mater, arachnoid mater, pia mater, CSF)

What is meningitis? What are the symptoms?

\-Infection/ inflammation of the meninges

\-h/a, painful neck, fever, large #WBC’s in the CSF

What is the gram reaction, morphology, and arrangement of Neisseriaceae?

Gram neg, diplo cocci

How is Neisseria meningitis transmitted?

\-When a carrier lives in close contact with a nonimmune individual. Secretions or droplets

\-(Once acquired, penetrates blood vessels, crosses the BBB and grows in the CSF)

Why are pregnant women advised not to eat sandwich meat and cheese?

To prevent Listeria Monocytogenes from causing neonatal meningitis (can cross placenta)

Name some of the microorganisms capable of causing meningitis?

\-respiratory droplets

\-living in close quarters

\-lunch meat

\-soft cheeses

Is bacterial or viral meningitis more serious?

Viral is more common, but bacterial is more serious

What is the most likely cause of neonatal meningitis?

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\-Strep agalactiae or E.coli

\-More likely in premature babies due to immature immune system

\-Can happen during birthing process

\-(caused by different microorganisms than in adults)

What is encephalitis?

Inflammation of the brain

(can occur in conjunction with meningitis)

What type of microorganisms cause encephalitis?

\-Herpes simplex virus

\-Varicella-zoster

\-JC virus

\-Arboviruses

Do patients recover from amoebic encephalitis?

No. They die

What are the vectors of arboviruses (generally, not specifically)?

Insects

How does toxoplasmosis spread?

\-can cross placenta

\-cat feces (part of their natural flora)

Sx of rabies

\-Incubation period: 1-2 months

\-Prodromal period: fever, N/V, H/A, fatigue

\-Furious period: neural sx, agitation, disorientation, seizures, pain on swallowing

\-Dumb period: loss of laterness and coherence

What animals carry rabies?

skunks, raccoon, fox, coyote, opossum, bat

What treatment is performed is someone is bitten by a potentially rabid animal?

4 vaccines over the course of 14 days

How does polio cause paralysis?

It infiltrates the motor neurons and destroys them

(infection of the spinal cord. Absorbed by the gut)

What causes tetanus?

Clostridium tetani (anaerobe!)

How is tetanus contracted?

\*anaerobe

\-found in soil and GI tracts of animals

\-spores enter the body through puncture wounds, burns, frostbite, and crush injuries

What causes botulism?

Clostridium botulinum (severe)

\*anaerobe

How is botulism contracted?

\-Soil, water, occasionally animal intestines

\-Usually occurs through eating contaminated canned food (spores on the meat or vegetables)

What is the vector for African sleeping sickness? Chagas disease?

\-AS sickness: Tsetse flies

\-Chagas: kissing bugs

Infection of what organ system ultimately causes death in ASS and Chagas disease?

Brain/ CNS

What is the function of the cardiovascular system?

Blood vessels:

\-arteries

\-veins

\-capillaries

Heart:

\-Epicardium

\-myocardium

\-endocardium (covers the valves)

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Function:

\-provide oxygen and nutrients

\-removes waste and carbon dioxide

What is the function of the lymphatic system?

Composed of:

\-bone marrow

\-thymus gland

\-lymph vessels

\-lymph nodes

\-spleen

Function:

\-source of immune cells and fluids

\-one way return of fluid from tissues to the CV system

What is endocarditis?

\-Inflammation of the endocardium (usually the valves, typically caused by an infection)

Acute:

\-bloodstream is challenged w/ high concentrations of bacterial cells.

\-bacterial colonization of valves:

-continued infection, systemic shock

-blockages

Subacute: slower onset

\-damage to heart valves encourages attachment of bacteria

\-oral cavity of the streptococcus genera

\-prophylactic therapy in advance is recommended

What is septicemia?

SX:

\-fever

\-AMS

\-GI distress

\-low bp (septic shock: leaky vessels, lack of volume, endotoxic shock: bacteria is producing toxins, G-)

Definition:

\-Blood poisoning, toxins, “going septic”

\-either bacterial or fungal (usually bacterial)

What is one of the major physiological results of septicemia that can result in death?

shock

Where can you find B. anthracis?

soil

How is B. anthracis transferred among livestock?

they eat from the soil

What are Koch’s Postulates?

1. the suspected organism must be present in every case of the disease but absent from healthy organisms
2. the suspected microorganism must be isolated and grown in a pure culture
3. the same disease must result when the microorganism is inoculated into a healthy host
4. the same microorganism must be isolated from the disease host

When can/can’t Koch’s Postulates be used?

\-when the microorganism won’t grow in another animal

\-if it won’t grow in the lab

What symptoms does B. anthracis cause?

\-cutaneous: necrosis of the skin where it entered (black scab)

\-ingestion or pulmonary: shock bc of the toxins

\-fever and inflammation

\-pulmonary: normal cold sx

What bacterium causes the black plague?

yersinia pestis (nonenteric yersinia)

What is the lifecycle of yersinia pestis?

it infects fleas and small rodents and humans.

Flea bite infects mammal and then bites you. you can spread lung to lung as well. direct contact with mammal

What diseases are caused by Borrelia species?

Lyme disease

\-carried by ticks

\-tick has two hosts, white footed mouse and deer

\-nonfatal disease that mimics neuromuscular and rheumatoid conditions

\-bulls eye rash at bite site

Relapsing fever

\-natural reservoirs are non human mammals

\-bacteria matures in the salivary glands of the tick

\-characterized by a fluctuating fever (due to immune response and the change in bacteria antigens)

Why does the fever fluctuate in relapsing fever?

the bacteria keeps mutating antigens, so your immune cells never keep up

How is Lyme disease transmitted?

ticks. The ticks have two hosts: white footed mouse and deer

\
What is the characteristic symptom of Lyme disease?

bulls eye rash (only in like 70% of cases tho)

What diseases are caused by the rickettsia family?

\-Typhus group

\-spotted fever group

What are the insect vectors for Typhus and Rocky Mountain Spotted Fever?

lice

body louse

What disease does Plasmodium cause?

malaria

What is the insect vector carrying Plasmodium?

female of several species of mosquitoes

(protozoan)

How does plasmodium replicate?

(equatorial)

through infected mosquitoes reproducing with other mosquitoes

What disease does Epstein Barr virus cause?

Mononucleosis

Herpesvirus

How is Epstein Barr virus spread?

direct oral contact

What chronic conditions can Epstein Barr cause?

\-Can cause some cancers (lymphoma and nasopharyngeal carcinoma)

\-Could be a trigger for multiple sclerosis

What type of virus is HIV?

retrovirus (RNA viruses which contain reverse transcriptase)

What tissues are infected with HIV?

White blood cells (specifically T cells)

What treatments are available for HIV?

drugs for targeting RNA production/ conversion

prophylactic drugs (prevention)

drug cocktails

What are the components of the upper respiratory system? Lower?

Upper:

\-nose

\-nasal cavity

\-sinuses

\-pharynx (throat)

\-epiglottis

Lower:

\-larynx (voicebox)

\-trachea (windpipe)

\-bronchi

\-bronchioles

\-Alveoli

How are streps categorized/classified?

\-Lancefield classification (group A, B, C, etc.)

\-hemolysis (alpha, beta, gamma)

Which strep species is the most serious pathogen?

streptococcus pyogenes (part of natural flora, but it is the most likely to grow out of control)

What virulence factors does S. pyogenes contain?

\-capsules

\-C5a protease (complement system)

\-hyaluronidase

\-streptodnase (DNAse)

What types of localized and systemic diseases does S. pyogenes cause?

Localized:

\-pyoderma (impetigo)

\-erysipelas (cellulitis)

\-pharyngitis (strep throat)

\-tonsillitis

\
Systemic:

\-scarlet fever

\-septicemia

\-pneumonia (only 5%, but very serious)

\-streptococcal toxic shock syndrome (30% mortality rate)

What long term complications can group A strep infections cause?

Rheumatic fever:

\-joint pain

\-heart damage

\-usually reversible

\
Acute glomerulonephritis

\-kidney damage

\-May be reversible, may result in kidney failure

What infections does S. pneumoniae cause?

\-intense inflammatory response results in fluid in the lungs

\-generally in immunocompromised people

\-meningitis

\-otitis media (infection of the middle ear)

\-lifetime memory

What type of microorganism causes diphtheria?

corynebacterium diphtheriae

What causes the symptoms of diphtheria?

\-fever

\-sore throat

\-difficulty breathing and/ or swallowing

\-swollen glands in your neck

\-pseudomembrane can develop on the pharynx (can cause suffocation)

\
\-Can happen one of two ways: respiratory or cutaneous (more common in homeless population)

What is the vaccine given for diphtheria?

DTap (mixed with tetanus and pertussis)

What disease does Bordetella pertussis cause?

Pertussis (whopping cough)

What causes the symptoms of pertussis?

\-infection leads to a buildup of mucus and blockage of airways

\-WAY more serious in infants