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92 Cards in this Set
- Front
- Back
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Results of microbe-human interactions
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a. Microbes acquired on exposed area of body
Infection = entry, establishment and multiplication of pathogenic organism in a host Disease—several outcomes |
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Normal flora
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resident flora, micro flora—are commensal organisms= benefit w/o harming host, sometimes host benefits as well
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Normal Flora Continued
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1. On body surfaces exposed to environment
2. Places to find normal flora= skin, mucous membrane, parts of digestive system, urinary tract, upper respiratory tract, reproductive tract 3. Colonization of normal flora—starts just before being born throughout life |
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Colonization of Normal Flora (ct)
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a. Inutero—germfree
b. Birth canal—lactobacillus (part of normal vaginal canal, becomes part of child’s intestinal floral c. 8-12 hours after birth: E.coli → large intestine and skin also staph bacteria that will colonize skin. Beneficial effects= produce vitamin K + B, aid in develop of immune system and GI sys |
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Some other human interactions
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ii. Some transients—on body for a short period of time
1. Cleaning 2. Immune system iii. Some→ allergy or hypersensitivities iv. Some with greater infectious potential evade host defense→ infection |
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Disease--Pathology
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the study of disease
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Pathogenesis
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creation/formation or how the disease develops
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Virulence
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the ability of a microbe to invade and damage host tissues
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True pathogen
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produce virulence factors that allow it to evade host defense cause damage
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Opportunistic pathogen
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not highly virulent (not normal/ not beneficial/ not normally harmful, but with the right opportunity of immune suppressed patients)
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Virulence factors
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Antipagocyte chemicals, enzymes, toxinsand endotoxins
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Antipagocytic chemicals
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Capsule
Leikocidins—kills WBC/poison |
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Enzymes
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Exoenzymes (digest host tissue→invasion)
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Toxins
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other chemicals that can cause damage to host
may affect local distain targets |
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Toxigenicity
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ability of a microbe to produce toxins at the cite where it grows/ is multiplying
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Toxemia
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toxins in the blood + spread
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Exotoxin
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protein secreted by bacteria w/powerful effects on a specific organ
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EX. Clostridium botulinum→ causes Botulism
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1. In soil—anaeroboic
2. Toxin= boulinum toxin a. Usually causes death b. Acts on CNS c. Blocks nerve conduction d. W/o nerve conduction= paralysis e. Includes all muscles (resp.) f. Block release of Ach from motor end plate g. Protein→ so denatured by heat |
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Endotoxin
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part of the lipopolysaccharide of G- outer membrane
1.Causes more generalized and weaker toxicity 2. Can cause pyrogenic response (fever) 3. Also—shock, inflammation, hemorrhage, diarrhea |
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Example of endotoxin
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E. coli, Salmonella
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Infection = entry, establishment and multiplication of pathogenic organism in a host
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1. Immune system can arrest infection before injury to tissue/organs
• 2. Infectious agent—not arrested o entrenched into tissue o pathologic effects cause damage |
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Disease—several outcomes
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• 1. Eventually—immune system arrest microbes and stop disease progression
• 2. Damaged tissues can lead to tissue/muscle/organ disfunction—morbidity • 3. Damage can be severe→ death (mortality) • 4. Microbe can be harbored inconspicuously (carrier state) |
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Mechanisms of Action of infection process
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entry, adherence, invasion, multiplication, disrupting of target tissues
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Entry- portal of entry
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= route by which microbe enters tissues
• Skin • GI tract • Respiratory tract • Urogenital tract • Placenta |
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Entry- Origin of Pathogens
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• Exogenous (outside of the body/from the environment)
• Endogenous (nf gone bad/ immunocompromised/ originate from normal flora) |
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Mechanism--what is also important
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size of infectious dose!
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Adherence
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o Microbes attach to host cell via:
• Fimbriae • Flagella • Capsule • Receptors |
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Classification of Infectious diseases
A. Based on transmission |
o 1. Contagious—easily spread from one host to another (cold/flu)
o 2. Route of transmission • a. Contact transmission direct—coughing, sneezing host→ host (w/o anything in between) indirect—intermediary (nonliving) is present; example= cup/ phone/ water cup, germs passed • b. Vehicle transmission water borne food borne air borne vectors (insects) |
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Based on the frequency
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o Epidemic= large # of people in restricted geographic area—get infected in short period of time
o Pandemic= like epidemic but world=wide o Endemic= not like big outburst, if you go to this country, it is always there; disease that is always present in a particular population |
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Disease based
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o Acute= rapid onset, relatively short duration
o Chronic = develops slowly, long onset, long duration |
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Stages of Infectious Disease Incubation Period
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period of initial contact with microbe→ appear of 1st symptoms
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Prodromium
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=period of initial, vague symptoms
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Period of Invasion
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variable period in which microbes multiply in high #’s, time of most severe symptoms
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Convalescent period
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period of recovery, decline of symptoms
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Botulism • 3 forms=
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o food borne botulism
o infant botulism o wound botulism |
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C. Botulism
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o G+ rod
o Anerobic o Soil o Makes 7 toxins A-G |
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Botulism In United States
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o ~145 cases/year
o 15% food o 65% infant o ~20% wound |
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Symptoms
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o Blurred vision
o Droopy eyelids o Slurred speech o Difficulty swallowing o Muscle Weakness→ paralysis onset (18-36 hours) 6 hours- 10 days (food) |
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Syphilis
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Treponema pallidum
o Human host o Sensitive pathogen • Can’t live outside host • Sensitive to: heat, drying, disinfectants, soap increased O2 levels, pH change o People in history who had disease • Bram Stoker • Henry VIII • Vincent Van Gogh |
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Pathogenesis
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• transported through: mucous membrane/abraded skin (STD)
• Spirochete w/hook Uses hook to bind to epithelial cells @ binding site→ multiply penetrate through the capillaries by dissolving junctions between the endothelial cells→ move into circulation and can get into blood vessels Once in blood vessels→ multiply more (body becomes incubator) Any tissue can be a potential target • Slow doubling/generation time→ slow, but progressive disease |
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Stages of infection (syphillis) Primary Lesion
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• microbe hooks cells
• inflmatory cells come to site—block circulation • treatment w/penicillin= EFFECTIVE • if untreated→ chancre site of inoculation (appears 9 days- 3months after coming into contact with 57 mic) small red bump that then breaks down and creates shallow crater @ base—swarming w/ microbes can have enlarged lymph nodes in affected region no head ache or fever • chancre heals 3-6 weakes when bacteria→ go to circulation (slowly b/c they double so slowly |
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Secondary Syphilis
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• between 3 weeks- 6 months
• depends on infectious dose • systemic→ many body systems invaded • HA/ fever/ soar throat/ lymph nodes swollen/ red & brown rash over all skin surface • Major complications→ bones, hair follicles, joints, liver, eyes, hair, kidneys • Symptoms usually disappear→ in few weeks can linger for months-years |
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Latent Syphilis
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• organism is still there, but no symptoms
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Tertiary Syphilis
a. cardiovascular syphilis |
die due to heart failure ~85%
damage to small aortic in aortic wall heart valves damaged heart failure |
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Summas
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painful, swollen syphilitic tumor
benign (NOT CANCER) center—necrotic tissue found in: skin/ bone/ liver/ cartilage |
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Neurosyphilis ~10%
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any part of the nervous system can be involved
usually blood vessels in brain: cranial nerves, & dorsal roots of spinal cord symptoms: HA/ convulsion/ atrophy of optic nerve (blindness)/ mental deterioration/ muscle wasting and loss of activity and coordination |
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The Tuskegge Syphilis experiment
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400 w and 200 w/o, injected told they were being treated, weren't CDC let it happen, able to pass it on to their families, 1932-1972
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**Cholera**
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• Caused by a bacteria—vibrio cholera
• Comma-shaped • Found commonly in soil and water –free living • Ingested in cont. food & water • Encounters acidic stomach→ penetrate tract mucous barriers, using flagella→ adheres to surface of epithelium of LI→ multiply (doesn’t penetrate further) |
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Virulence of Cholera microbe- virbrio cholera
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enterotoxin= cholera toxin (targets mucous membrane of intestinal cells)
o Toxin binds receptors on the intestinal cells → activates a signaling cascade→ cells send electrolytes into LI (not in cells or passed into tissues→ they are shed through the LI, water will follow) → diarrhea/ vomiting → dehydrated o Loss of blood volume K+ depletion→ bicarbonate loss→ acidosis/ coma/ shock = death |
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Treatment
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o *****Water***** and electrolyte replacement (Bananas)
o Tetracycline |
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Defenses of the Nervous System
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• Structural—boney structures
• CFS • Blood-brain barrier |
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Normal Flora of NS
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Any microbes in the peripheral or central indicate infection—NOT NORMAL TO BE THERE
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Meningitis
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• Inflammation of the meninges (covering around the brain)
• Can be caused by bacteria/virus • Diagnose: symptoms, spinal tap/CP, and Gram stain |
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Meningitis (s & s)
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o Head Ache
o Painful/stiff neck! o Light sensitivity! o Fever o Increase in # of WBV in CSF |
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Neisseria meningitis-Characteristics
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o Bacteria that can cause meningitis
• G- • Diplococcus • Memingococcus • Most often associated with outbreaks/epidemics of men. • Causes most serious form of meningitis |
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Transmission
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• doesn’t survive long in the environment
• respiratory droplets/ close contact or secretions |
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Virulence factors and infections
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• in the nasopharynx→ spread to the roof of nasal cavity→ boarders highly vascular area @ base of the brain (usually asymptomatic) → use polo to attach to mucosa (carriage state)—can last few days, several months (3-30% of adult population have this) –spreads when in close proximity—cause infection to non-immune individuals → enter blood stream → CSF→ penetrates meninges (fever, soar throat, HA, stiffness, convulsions, vomiting) → can lead to meningococcemia (in blood) → bacteria release an endotoxin into general circulation→ stimuli WBC → release cytokines (too much) → BV damage/hemorrhage/ intravascular clotting→ cardiac failure/ damage to adrenal glands (on kidneys—epinephrine)→ death
• also has IgA protease and capsule |
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Treatment
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• natural immunity via exposure early in life
• penicillin G (high dose, usually IV) • vaccine—trying to make one • if treated—15% mortality rate • Prophylaxis for anyone in close contact: tetracycline/ rifampin |
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Viral Form of meningitis
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o Similar symptoms
o No antibiotic cure unless infection caused by herpes • Supportive o More common than bacteria meningitis o Virus more readily cross blood-brain barrier o Spread: resp., drops, feces |
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Encephalitis
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• Inflammation of the brain
• Extremely sensitive to damage caused by the inflammatory process |
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Encephalitis Characteristics
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o Can be acute or sub-acute
o Almost always caused by virus→ especially acute o Viral infection→ insect borne o Can be caused by bacteria |
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Encephalitis Symptoms
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o Behavior changes (moody—severe)
o Confusion o Seizures o Similar symptoms of meningitis can be present |
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Arboviruses
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o Are all arthropod borne/ spread by insects
o Ticks/ mosquitos |
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Arboviruses types
A. Western equine encephalitis (WEE) |
In western US/ Canada
ssRNA virus enveloped mortality 5% normal host: wild birds also found in horses—able to infect humans-jump |
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West Nile Encephalitis (WNE)
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ssRNA
enveloped found on eastern coast of US/Canada/ Africa/ Uganda host: wild birds |
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Eastern equine encephalitis (EEE)
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Eastern Coast and Canada
ssRNA enveloped wild birds = host to horses to humans 50% mortality |
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Pathogenesis of EEE
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• Host= bird
• Mosquito acquires virus from bird • Mosquito bites a human (in saliva of mi) • Virus enters blood stream via mosquito’s saliva • Replicates in monocytes (WBC in circulation and nearby lymphatic tissue) o Enters endothelial cells (capillary) → prolonged viremia→ enters CNS (either direct or with viremia)→ damages perikaryon (cell body of nerve cells) & dendrites → brain→ with immune response (inflammation of the brain)→ damage (brain/nerve/meninges) o Crosses placental barrier and can infect fetus |
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Virulence Factors of Arboviruses
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• Not well understood
• Enveloped—pieces of this facilitate attachment in body to specific cells • Proteins in the env. that promote fusion w/host cell membrane |
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Symptoms/ Arboviruses
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• when virus is in lymphatic tissue
fevers/ chills/ weakness/ swollen lymph nodes/ HA • 4-10 days after bite severe memory deficits tremors loss of coordination personality changes, can be severe w/o reas. Convulsions Speech changes Coma/death |
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Treatment
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• supportive
• may try antiviral drugs • vaccine—lab workers/ vets/ ranchers/ horse handlers • live attenuated |
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Clostridium tetani
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• Tetanus—stiff neck, spasms, sweating
• Affects axon of the neuron and the spinal cord & brain (muscle spasms) • Treatment: clean wounds, bed rest, non-stimulating environment, tetanus immunoglobulin is also used. |
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Mycobacterium Tuberculosis
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• Tuberculosis
• Bacteria—alveoli of lungs, if stays there =pulmonary TB, if not exterior TB (obligate aerobe) • Treatment: Streptomycin—along with: isoniazid & ethambutol • Vaccine: Bacille Calmette- Guerin (BCG vaccine) |
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HIV—Human immunodeficiency Virus
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• Retrovirus—attacks and destroys the immune system (t-lymphocytes)
• Causes AIDS • No vaccine/ no cure only medications to slow process |
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Yersinia pestis
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• Bacteria –member of enterbacteriaceae family
• Causes: Black Death/ Plague (from rodent); fever, chills, red rash (ring around the rosy) 75 % mortality rate • Treatment: streptomycin/tetracycline, also gentamicin and chloramphenicol, for septicemic plague: isolation/antibiotics (doxycycline, supportive care) • Prophylactic treatment for suspected exposure, 7-10 day antibiotics |
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Hepatitis B
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causes Hep. B
• Virus-Hepadnavirus family • Affects liver cells • Fatigue, nausea, jaundice, liver cancer/ blood tests • Preventions: avoid used syringes, vaccination, safe sex • No treatment usually needed, but for chronic: interferon alfa-2b, and lamivudine |
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Variola Virus
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• Virus
• Causes smallpox • Transmitted through: inhalation of droplets or dried crusts, body fluids • Blood and lymph (spreads through the entire body) • No Treatment! Treat symptoms→ prevention! • Vaccine! Very contagious and very fatal! |
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Lassa Fever Virus
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• Virus
• Lassa Fever • Transmission: food contaminated through feces of rat/ air with rat feces/ bodily fluid • Works specifically on the blood vessels—capillary lesions • Rifampin |
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Streptococcus Pyogenes
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• Colonizes on the throat or skin, also heart valves and tissues
• Causes impetigo, strep throat, scarlet fever, pneumonia, necrotizing fasciitis, streptococcal toxic shock syndrome • Bacteria • Treatment: penicillin/ amoxicillin/erythromycin/ beta lactams • Oral cephalosporin |
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Varcella- Zoster Virus (human herpes virus 3)
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• Virus
• Chicken Pox/Shingles • Transmitted through: droplets/ lesion contact • Nerve cells • Treatment: applying lotions, not touching/scratching, antiviral meds. • 2 vaccines: varivax/ Zostavax |
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Clostridium botulinum
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• Botulism
• Bacteria • Not harmful to the host by itself • Endospores are the cause • Affect the nerve cells (neuromuscular junction bloakcage of AcH) • Treatment: supportive care, botulism immunoglobulin, mechanical ventilation, tube feeding, antibiotics are not used, because massive death of these cells, which would creates toxin |
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Haemophilus influenza
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• Bacteria
• Respiratory (alveoli) / organs/ inflammation of the meninges • Meningitis, pneumonia, bacteremia • Vaccines and boosters (1-year) • Treatment: combination of antibiotics |
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Aroboviruses (3 different families)—West Nile Virus (transmitted via arthropods)
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• Falviviruses
• West Nile Encephalitis • transmitted through birds by mosquito bite • cerebral capillary endothelial cells into CNS (dendrites, perikaryon, myelin sheaths) • Treatment: symptomatic treatment. No vaccines |
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Hantavirus
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• Virus
• Can only get it through rodent; through inhalation of feces, saliva • Hantavirus pulmonary syndrome—vessels and capillaries of lungs • Hemorrhagic Fever with Renal Syndrome—vascular endothelium • Treatment: manage fluid and electrolytes, Ribavirin |
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Human Papillova Virus
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HPV
Virus Epithelial cells Treatment: removal/surgery, medication |
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Poliovirus
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• Poloi Virus
• Motor neuron cells • Treatment: no cure, but to control symptoms (orthopedic braces) and iron lung (artificial respirator), 2 vaccines! |
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Nuclear polyhedrovirus
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• Virus
• Wilting/ Melting disease • Gastrointestinal cells • Treatment→ not finding treatment (used for insecticides) |
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Toxoplasam Gondi
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• Parasite
• Toxoplasmosis (in fetus and immunodifficient people) • Oocysts/ neurological • S/S—mental status changes, fever, muscle pain • Wash hands. Litter box clean, avoid raw food, wash all fruits |
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Neisseria Gonorrhoeae
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• Gonorrhea
• Bacteria • Epithelial tissue • Painful urination/ 50% of women asymptomatic (destroy fallopian tubes) • Treatment: inject mercury into the tip of the penis→ penicillin→ flouroquinilones→ sephlosporines |
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Staphylococcus aureus
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• MRSA
• Epithelial cells • Treatment with: lotion/topical, antibiotics (vancomycin) • Prevention: wash hands |
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Borrelia Burgdorferi
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• Lyme Disease
• Bacteria • Lymph • Treatments: antibiotics (doxycycline, amoxicillin, cefuroxime; ceftriaxone, penicillin) • Repellant and wash clothing |
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Bacillus anthracia
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• Anthrax
• Bacteria • Neutrophils/ Lungs • Treatment: vaccine, antibiotivs—ciproflaxicin and doxycycline |
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Rabies Virus
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• Nerve cells, all animal cells
• Treatment: seek medical care, vaccine, tetanus shot |
