Infectious Disease Flashcards
Candidemia
fungus
- presence of Candida in blood- c. albicans most common cause (nosocomial)
- pathogenesis: through gastointestinal tract muscosal barrier, IV catheter, TPN, localized focus of infection
- clinical manifestations: minimal fever to sepsis, indistinguishable from severe bacterial infection, defined by hematogenous spread to multiple viscera (eye, skin, mm knots, multiorgan system failure)
- risk factors: patients in ICU (any invasive procedures) and immunocompromised
- diagnosis: blood culture is gold standard but results take time so beta-D-glucan assay and PCR may work… in meantime stop antibiotics and steroids as these depress IS and give antifungal
Blastomycosis
fungus
- reportable disease in MI
- spreads lympho-hematogenously to extrapulmonary sites
- symptoms: acute (self-limited) is flu-like or pulmonary (over 50% asymptomatic or minimally)
- incubation: 45 days
- risk factors: infected soil esp along waterways
- diagnosis: culture from sputum/lesion (not serologic tests or urine antigen test)
Coccidioidomycosis
fungus
- systemic infection, community acquired infection
- Valley fever
- found in soil of dry areas,
- incubation 1-4 weeks
- presentation: self-limited or subacute community-acquired pneumonia, cough, fever, chest pain, fatigue, rash/lesions
- diagnosis- IgM and IgG, fungal culture, CXR
- treatment: antifungal (“azoles”), antitussive, NSAIDs…follow up 2 weeks
- complications: meningitis, hemoptysis
Histoplasma capsulatum
fungus
- reportable disease in MI
- most asymptomatic/subclinical
- clinical presentation: (acute) fever, chills, chest pain, weakness, myalgia, (chronic pulmonary- anorexia, night sweats, productive cough)…disseminated: hepatosplenomegaly, mucosal ulcers, skin lesions
- diagnosis: confirmatory w/ rise in compliment fixation, culture, DNA probe, CXR
- treatment: self-limited, but if severe antifungals
Clostridium botulinum
- Endospore
- Blocks release of Ach from peripheral n.–>prevent contraction–> flaccid paralysis (no respiration)
- Causes: food borne infection- improperly prepared home-canned, low-acid foods, honey, leftover baked potatoes in aluminum foil
- Symptoms: onset 12-36 hours, lasts for several weeks…blurred vision, constipation/abdominal discomfort, mm weakness, death due to respiratory failure.
- Diagnosis- fecal material culture…lab tests presence of toxin in serum or stool (7 days for results), routine tests not very helpful, CSF testing to differentiate from Guillain-Barre syndrome, and normal tensilon test to differentiate from mysathenia gravis
- Treatment: antitoxin therapy (begin when waiting for results), mechanical ventilation
Vibrio cholera
bacteria
-spread through contaminated drinking water and unsanitary conditions
-gram -, facultative anaerobic, unipolar flagella
secretes cholera toxin causing watery diarrhea, dehydration
Salmonella
baceria
gram -, most pathogenic species in humans
-symptoms: gastroenteritis, bacteremia (rash), enteric fever, localized infection outside of GI tract, nausea, diarrhea, vomiting, headache
-ingested in contaminated food or water mostly
-symptoms usually occur 12-72 hours after ingestion and resolve within 4-10 days
-diagnosis- stool, CBC, blood cultures
-treatment: antibiotics if immunoincompetent with severe
-compliactions possible with meningitis and endocarditis (high mortality)
Shigella
bacteria
gram -, non-motile, bacilli, only 10-100 cause disease, human only reservior
-incubation 1-7 days
-self limited, transmitted from person to person, contaminated food and water, fecal-to-oral
-symptoms: NO NAUSEA OR VOMITING, fever, diarrhea with bloody stool but not significant fluid loss
-may lead to Reiter’s syndrome and chronic arthritis
-diagnosis- stool culture, PCR
-treatment- antibiotic
Clostridium tetani
bacteria
- Endospore- present in soil and dust; anaerobic
- 1-54 days incubation…shorter incubation=higher risk of death
- Exposure: injection of bacteria (non-oral route); tetanospasmin which is irreversibly bound to tissue, exotoxin tetanolysin (hemolysin)
- Mechanism of action: binds to Ach which causes activation
- Diagnosis- clinical signs and symptoms- Risus sardonicus (locked smile), opisthotonus (back spasms), autonomic instability (bp, cardiac, respiration, dehydration), trismus (lock jaw)
- Morality- 50-75%…treatment- wound management and immunoglobulin…prevention DTap (pediatrics), Tdap (older kids and adults), DT (pediatric but for kids who can’t handle acellular Pertussis component), Td (every 10 yrs older kids and adults)
Bacillus anthracis
bacteria
inoculation from direct contact with infected animals, carcasses or animal products, and contaminated soil.
Inhalation or ingestion of spores may occur
Clostridium difficile
bacteria
- Endospore; worse strain is NAP1
- Gram positive bacteria causing severe diarrhea; anaerobic, resistant to heat and alcohol and acid; viable for months on dry surface
- Low number of load to cause symptoms; Broad spectrum antibiotics may allow c.diff to flourish; Can lead to pseudomembranous colitis; nosocomial and iatrogenic
- Produces toxins responsible for diarrhea and inflammation (enterotoxin and cytotoxin); Virulence: A (entertoxin) and B (cytopathic); Antibiotic resistant
- Symptoms: watery diarrhea, fever, loss of appetite, nausea, abdominal pain/ tenderness, mild to sever toxic mega colon
- Treatment: discontinue antibiotics, fecal transplant,
Mycobacterium tuberculosis
mycobacteria
Acid-fast stain positive because of thick mycolic acid in cell wall…also means that organism grows slowly, is more resistant to chemical agents and lysosomal components of phagocytes, and has far fewer porins.
Pathogenic filamentous- tends to cause chronic disease
Obligate aerobe- requires O2
Latency-remains dormant for some time before causing disease at a later date
Malaria
parasite
- plasmodium falciparum; tropical and subtropical
- stage 1 shaking chills, stage 2 pyrexia and severe headache and stage 2 sweating stage, anemia, asthenia, splenomegaly
- treatment: malarial chemoprophylaxis (atovaquone, doxycycline, chloroquine, primaquine)
Ebstein Barr Virus/Human Herpes Virus 4
virus
typical presentation in young adults 15-25 yrs
classic triad of fever, pharyngitis, and lymphadenopathy
atypical presentation gastoenteritis
Influenzavirus
virus
- Orthomyxovirus- spherical or oval-shaped, RNA virus (A,B,C or H1N1 also affects GI)
- Acute, usually self-limited, febrile infection
- Antigenic shift- genes are interchanged among different stains= new strain
- Antigenic drift- small changes to one strain creates a new strain
- Risk factors: semiclosed environments, crowded, close environments
- Complications: infants, elderly, pregnancy, chronic pulmonary diseases, cardiovascular diseases, metabolic diseases (diabetes), hemoglobinopathies, malignancies, immunosuppression, neuromuscular disesaes (CF)
- Incubation 1-4 days, recovery is usually spontaneous and rapid 7-10 days
- Symptoms: higher fever, chills, malaise, myaligia, headache, rhinorrhea, sinusitis, sore throat, non-productive cough
- Lab diagnosis: RIDT- 15 min, CBC, PCR, ELISA
- Treatment: antivirals most effective within first 48 hours, decreases duration of symptoms
Lyssavirus
virus
Causes rabbies (RNA virus in family Rhabdoviridae).
Virus laden saliva via bite, scratch, or abrasion.
Causes 55,000 human deaths worldwide, mostly in Asia and Africa
1. Incubation period- 10 days to 1 year, with average of 20-60 days
2. Prodrome- 1-14 days with symptoms of pain or paresthesia at bite site and nonspecific flulike symptoms, including fever and headache
3. Acute neurologic period: 2-20 days…either furious rabies (hyperactivity for 5 min, hydrophobia, aerophobia, hyperventilation, hypersalvation, and autonomic instability) or paralytic rabies (paralysis, possibly ascending or differential)
4. Coma- lasts hours to days, may be sudden with respiratory arrest
5. Death usually occurs within 3 weeks of onset due to complications.
Bordetella pertussis
bacteria
- gram negative, aerobic coccobacillis
- filamentous hemataglutin attached to respiratory cilia
Borrelia burgdoferii
-Spiral- tends to cause systemic disease
Treponema pallidum
-Spiral-tends to cause systemic disease
Trichinella spiralis
helminthic zoonoses infection
intestinal nematode
transmitted by ingesting insufficiently cooked meat
Leishmaniasis
parasite
spread by the bite of the sandfly and found in most tropical countries
-diagnosed with needle aspirate, immunologic test
-no vaccine
-cutaneous forms: skin ulcers
-mucocutaneous forms: lesions in mucos membranes
-visceral (kala azar): high fever, weight loss, hepatosplenomegaly and anemia; fatal 100% w/in 2 yrs if untreated
-treatment: IV med liposomal amphotericin B
Rickettsia rickettsii
obligate intracellular
-causes rocky mountain spotted fever
Schistosoma
parasite
- snail fever…diseases of liver, GI tract and bladder caused by trematode worms
- endemic in developing countries
- flukeworms mate and lay eggs in hepatic portal blood vessels
- incubation 14-84 days
- symptoms: rash, itching, fever, rigor, coughing, mylagia
- diagnosis: stool/urine samples, serologic test for antischistosomal Ab
- treatment with Praziquantel single dose curative
- no vaccine available
Endogenous v exogenous pyrogens
Endogenous- cytokines (esp IL-1,IL-6, TNF, and prostaglandin E2)
-migrate to circumentricular organs of brain and
activates toll-like receptors on vascular
network supplying thermoregulatory center in
ant. hypothalamus
Exogenous- on bacteria for example LPS, gram negative, endotoxin
external characteristics of bacteria
slime layer (gelatinous polymer, grame -, glyocalyx
pili and fimbriae for adhesion
cilia and flagella for motility
Metabolic properties
aerobe (requires O2)
anaerboe (abscesses)
obligate aerobe (require O2 in some form) microaerphiles (require O2 in inorganic form like CO2)
Types of gene transfer
Conjugation (plasmid exchange)
Transformation (free floating or exogenous DNA via recombination)
Transduction (bacteriophages)
Transposition (interrupts gene when it is inserted)
Classification of viruses
- phenotypic characteristics
- ICTV (order, family, subfamily, genus, species)
- Baltimore (nucleic acid, strand, sense, method of replication)
What are some tests for fungal infections?
immunodiffusion, complement fixation
