Diseases Flashcards
Clostridium difficile
Etiologic agent:
- Gram +, rod shaped
- Flagella, fimbriae
- Vegetative and spore states
- Anaerobic
- Toxin A & Toxin B
Pathophysiology/symptoms
- Toxins → pseudomembranous colitis → pus pockets → diarrhea, colon rupture, death
- Diarrhea 10-15x a day, nausea, weight loss, fever, dehydration
Transmission
-Fecal-oral: touching contaminated surface then touching mouth; mouth, food
Diagnosis
- Stool test: PCR, enzyme immunoassay, cell cytotoxicity assay
- Colonoscopy, X-ray
Prevention and treatment
- Handwashing and sterile techniques
- Antibiotics (vancomycin and metronidazole)
- Surgery (colectomy)
- Fecal microbiota transplant
Gonorrhea vs Chlamydia
Etiologic agent
- G: Neisseria gonorrheae; non motile coccoid bacteria
- Obligate intracellular bacterium (lack metabolic pathways)
- C: chlamydia trachomatis; gonococcal pili
- Intracellular aerobic diplococcus
- Oxidase +
- Utilizes glucose
Pathophysiology/symptoms
- G: antigenic characteristics
- Antibody resistant genes (penicillin)
- Susceptibility to host re-infection
- C: epithelial columnar cells
- Biphasic life cycle
- Prevent phagosome-lysosome fusion & produce reticulate bodies
Transmission
- STD – oral and vaginal
- Vertical transmission: parent → newborn
- In fallopian tubes
- Super infection: chlamydia → gonorrhea
Diagnosis
- Cell cultures
- NAATS – non culture tests that amplify the sequence of nucleic acid (urethral or endourethral)
Prevention and treatment
- Antibiotics (doxycycline, azithromycin, erthyromycin, levoflaxin)
- Condoms and sex ed, STD testing
Lyme disease
Etiologic agent
- Borella burgdorferi (bacteria) – spirochetes – very motile (specialized endoflagella)
- Aerobic or microaerobic
- Slow growth, very fastidious
Pathophysiology/symptoms
- Lesions
- Stage 1 early localized – lesions, red rings around bite site; lymph nodes swollen and normal symptoms (nausea, fever, etc)
- Stage 2 early disseminated – bacteria spreads thru blood to inflame tissues
- Stage 3 later/chronic – muscle and joint conditions, neurological, skin conditions
Transmission
- Backlegged deer tick
- Egg → larva → nymph → adult nymph transmits more often
- Humans aren’t only host – become infected by the deer or mice that they feed on
Diagnosis
- Tick exposure and blood tests
- Enzyme-linked immune-sorbent assay (ELISA): reads antibodies; if positive →
- Western blot test: reads antigens; rules out false positives
Prevention and treatment
- Antibiotics – recovery time varies
- 10-15% of patients who take antibiotics experience Jarisch-Herxheimer reaction → presents worse symptoms due to death of bacteria
Norwalk Virus
Etiologic agent
- Single positive stranded RNA virus
- Hexagonal capsid, amorphous surface, 32 cup shaped depressions
- Icosahedral symmetry
Pathophysiology/symptoms
- Virus in small intestine → fat malabsorption → enzymatic dysfunction at brush border → leak flux and anion secretion → changes in gastric motility and delayed gastric emptying
- Nausea, vomiting, diarrhea, headaches, fever
Transmission
-Fecal-oral (contaminated vehicles); person to person; airborne
Diagnosis
- Electron microscopy
- ELISA immunoassay
- Nucleic acid amplification
Prevention and treatment
- Wash hands, food, sterile surfaces
- No vaccine, no treatment or medication
- Oral fluid and electrolyte replacement, antiemetics, analgesics, anti peristaltic agents
Polio
Etiologic agent
- Picornaviridae (family), enterovirus (genus)
- Single stranded RNA core, surrounded by protein capsid
- Non enveloped, icosahedral
Pathophysiology/symptoms
-Mouth → replicates at pharynx & GI tract → lymphoid tissue → bloodstream → infect cells of CNS → replicate in motor neurons of anterior horn and brain stem → cell destruction → manifestation of polio myelitis
Transmission
- Fecal oral (contaminated food or water, sewage)
- Person to person (droplets)
Diagnosis
- Throat specimen, fecal specimen
- Virus isolation, RT-PCR, partial genome sequencing, serologic testing
- CSF analysis
Prevention and treatment
- Vaccine (IPV or OPV)
- Research and education
- Monitor sewage and water supplies
Ebola
Etiologic agent
- Filoviridae (family), ebolavirus (genus)
- Linear strands of RNA
- Caused by 5 distinct viruses: ebola virus, Sudan virus, Tai’ Forest virus, Reston virus, Bundibugyo virus
Pathophysiology/symptoms
- Target immune cells, liver and adrenal glands
- Weakened immune system makes them susceptible to other diseases
- Liver overproduces coagulation proteins in blood → clots
- Adrenal gland raises BP & along w/weakened blood vessels → bleeding and swelling
Transmission
- Bodily fluids (sweat, vomit, urine, semen, mucus, diarrhea, etc)
- Can survive outside the body: several hrs in dry conditions, several days in fluids
- Zoonotic (bats)
Diagnosis
-ELISA, antigen capture detection tests, serum neutralization tests, RT-PCR assay, electron microscopy, virus isolation by cell culture
Prevention and treatment
- Reduce risk of wildlife to human contact
- Animals handled w/protective clothing and gloves
Tuberculosis
Etiologic agent
- Mycobacterium tuberculosae
- Non motile, aerobe, acid fast, filamentous, waxy cell wall
- Facultative intracellular parasite
- Slightly curved baccilus
Pathophysiology/symptoms
- Use immune system to form granulomas called tubercles → can be dormant or not → tubercles can enlarge → cause cavities in the lungs → leak bacteria → severe coughing and bloody sputum → granulomas can travel
- Severe coughing, bloody sputum, chest pain, weakness
Transmission
-Person to person (droplets) coughing, sneezing, speaking
Diagnosis
- Clinical: signs, symptoms, history
- Imaging: x ray, CT, MRI
- Skin test, blood test
- Bacteriology: acid fast, culture, PCR
Prevention and treatment
- Vaccination (BCG)
- Meds: take the entire course
- If infected: stay home, ventilate the room, cover mouth, wear mask
West Nile Virus
Etiologic agent
- Flaviviridae (family), flavivirus (genus)
- Spherical enveloped single stranded RNA virus
- Nonmotile, no staining
- Receptor mediated endocytosis
Pathophysiology/symptoms
- Bite → infection in keratinocytes → immune cells in epidermis → draining lymph nodes → peripheral organs
- Neuroinvasive mechanisms – disruption of BBB
Transmission
- Primary route: mosquitoes – feed on infected birds → feed on humans or animals → dead end hosts (humans, horses, dogs)
- Alternate routes: thru contact w/other infected animals, their blood or other tissues
Diagnosis
-IgG antibody sero-conversion, IgM antibody capture ELISA, MIA, PRN test, IFA, hemagluttination inhibition, RT-PCR assay, lumbar puncture, brain tests
Prevention and treatment
- Awareness – stay away from places w/a lot of mosquitoes; preventing infection in health care setting
- Treatment: no antiviral or adjunctive therapies approved or recommended
Zika virus
Etiologic agent
- Flaviviridae (family), flavivirus (genus)
- Non motile
Pathophysiology/symptoms
- Infects epidermal keratinocytes → skin fibroblasts → Langerhaans cells → thought to continue to the blood stream and lymph nodes
- Swollen lymph nodes on side of neck, joint pain, rash, body aches
Transmission
- Mosquitoes
- Sexual transmission, in utero, blood transfusion
Diagnosis
-Urine sample or blood test
Prevention and treatment
- Nonspecific meds or vaccine
- Rest and acetaminophen
- Sexual protection, bug repellents, avoid bites, postpone travel if pregnant
Giardia
Etiologic agent
- Giardia intestinalis
- Trophozoite form: rigid cytoskeleton, posterior flagella, 2 symmetrical nuclei, teardrop shape
- Cyst form: oval, smooth walled
Pathophysiology/symptoms
- Cyst ingested from water/food → exocystation occurs: in presence of acid or pancreatic enzymes → parasite passes into small bowel and multiply rapidly → pass into large bowel → cysts passed back into environment thru fecal matter → cycle repeats
- Diarrhea, gas
Transmission
-Fecal oral (contaminated food and water)
Diagnosis
- Symptoms: diarrhea, gas, abdominal cramps, nausea, weight loss
- Stool samples: identification of trophozoite and cysts in stool must be present
Prevention and treatment
- Good hygiene – avoid consuming contaminated food or water
- Multiple drugs: metronidazole, thinidazole, nitazoxanide
Ringworm
Etiologic agent
- Tinea – fungus
- Dermatophyte, produce keratinase
- Dermatophyte cell walls contain mannin which inhibits the body’s immune response
Pathophysiology/symptoms
- Warm moist environments
- Fungus grows down stratum corneum → invades keratin → keratinase enzyme released to invade deeper
- Hair becomes brittle and breaks, skin grows concentrically
Transmission
-Direct and indirect (some from soil, some from object to human, domestic animals, infected human to human)
Diagnosis
- Depends on symptoms and lesion location
- Scraping of lesions, collecting bits of hair, scrapings of underneath nails, specimens treated
- Microscope, Wood’s lamp
Prevention and treatment
- Don’t share towels, shoes or sports gear; wear shower shoes
- Topical fungal agent, ointments (help speed up loss of outer skin layer)
Chicken pox
Etiologic agent
-Varicella virus
Pathophysiology/symptoms
- Mucous membranes → host cells in nose surrounding lymph nodes → liver, spleen, sensory nerve tissues → skin cells
- Fever, fatigue, headache, itchiness, redness, blisters
Transmission
- Airborne
- Direct contact
Diagnosis
-Itchiness
Prevention and treatment
-Calamine lotion, colloidal oatmeal baths, short fingernails, no antibiotics, vaccine
