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
