Infectious Disease Flashcards
fungal infections
opportunistic infections: attack weak immune systems (immunocompromised patients)
fungal infections - risk factors
neutropenia (cellular immunodeficiency) DM renal failure post-transplant IVDU chemotherapy, corticosteroids parenteral nutrition recent surgery broad spectrum ABX use ICU stay
candida, mucous membranes
fungal infection
oral: most common (angular cheilitis - corner of mouth, white plaque, red plaques w/ dentures)
GI tract/esophagus: odynophagia (pain w/ swallowing), GERD, biopsy to confirm (think immunocompromised)
GU: white, curd-like discharge, irritation and pruritus (balanitis in males)
- KOH: pseudo-hyphae (dx)
candida, skin infections
likes moist, dark, warm places
features: red, pruritic lesions, distinct borders, satellite lesions (pustules)
nails: onychomycosis, paronychia (chronic)
candida, disseminated
see in very sick people; often deadly
candidemia (in blood stream): from catheters or invasive instrumentation)
endocarditis: IVDU (large vegetations on eco)
chronic disseminated (aka hepatosplenic): occurs w/ leukemia pts (kids) undergoing aggressive chemo; see punched out lesions on liver via CT
dx: positive blood culture
candida treatment
remove cause (invasive instrument) and then tx underlying dz:
- most anti-fungals interfere with fungal cell membrane or wall formation
- fungus grow slowly and die slowly, so tx for long time
Azoles:
topical: clotrimazole, miconazole
systemic: fluconazole, itraconazole
Terbinafine: dermatophytes (paronychia, onychomycosis)
cryptococcus
encapsulated budding yeast
found in soil, pigeon feces
transported to immunocompromised people via inhalation:
- pulmonary infection (COPD, chronic steroid use, post-transplant)
- meningitis (very sick pts with CD4<50… AIDS pts)
cryptococcus: pulmonary
sxs: fever, cough, dyspnea, pneumonitis
dx: culture, staining (india ink or methenamine silver)
tx: fluconazole (10 wks)
cryptococcus: meningitis
sxs: H/A, N/V, confusion, fever, vision changes, see access on CT scan (cryptococcomas)
dx: CSF (inc. protien, WBC, dec. glucose); CT or MRI (cryptococcomas, hydrocephalus)
tx: fluconazole (mild dz), induction with amphotericin B than lifelong fluconazole
histoplasmosis
fungus
found in: soil, bird and bat droppings
transported to immunocompromised via inhalation
histoplasmosis - 3 types of disease
- chronic progressive pulmonary dz (elderly, COPD)
- patchy cavitations, calcified hilar nodes, pericarditis - progressive disseminated dz (HIV, CD4<300)
- fever, dyspnea, cough, ulcers, hepatosplenomegaly, adrenal insufficiency - disseminated dz (severe immunocompromised, AIDS, CD4<100)
- fever, septic shock, multiplee organ involvement, miliary pattern on CXR
histoplasma - labs, dx, tx
labs: anemia of chronic dz, bone marrow failure, inc. all phase, LDH, ferritin
Dx: bronchoalveolar lavage, serum antibody titers, blood culture
Tx: itraconazole (mild dz), amphotericin and lifelong itraconazole (severe)
pneumocystis
fungus, ubiquitous, airborne
effects premature or debilitates infants and immunodeficiency states
pneumocystis - sxs
sxs: abrupt onset, fever, tachypnea, dyspnea, cough (nonproductive), bibalilar crackles
pneumocystis - dx
CXR: diffuse interstitial infiltrates
PFT: dec. in vital capacity and total lung capacity; hypoxemia, hypocapnea
- HINT: rapid desaturation following removal of oxygen
Dx: get a sample (sputum or bronchoalveolar lavage) and stain
pneumocystis - tx
TMP-SMX (bactrim)
steroids: only in early tx
prophylaxis: TMP-SMX daily for pts w/ CD4<200 (very immunocompromised)
botulism (clostridium botulinum) - characteristics
gram-positive rod
found in soil, anaerobic, spore-forming
release toxin A, B
inhibits release of acetylcholine (neuro-muscular junction)
botulism - how contracted
food-borne (ingest toxin - home canning)
infant (honey - ingest spores)
wound (farmers, migrant workers; toxin produced in wound)
bioterror potential
botulism: manifestations
12-26 hrs after ingestion
- N/V
- vision changes (diplopia, loss of accommodation)
- dry mouth, dysphagia, dysphonia
- respiratory paralysis
baby: flaccid, weak
note: no sensory changes or fever
botulism: treatment
botulinum antitoxin (w.in 24 hrs)
manage respiratory failure
parenteral fluids
report to health department, CDC
cholera (vibria cholerae) - characteristics
gram-negative flagellated rod
ingested through fecal/oral route; contaminated water or food (epidemics, natural disasters)
activated adenylyl cyclase in intestinal epithelia = hyper secretion of water and chloride
cholera - manifestations
acute onset
“rice water” stool (gray turbid)
leads to dehydration and hypotension
diagnostics rarely indicated (usually clinical dx): can do stool culture
cholera - tx
fluid replacement - PO is best but IV if PO not tolerated
prevention: vaccine (short-lived for workers going into contaminated areas)
diphtheria (corynebacterium diphtheria) - characteristics
gram-positive bacillus
respiratory transmission
develops exotoxin that inhibits elongation factor required for protein synthesis
- see respiratory secretions
diphtheria - prevention
DTap: children < 7; 5 doses
Tdap: older children, adults
- booster every 10 yrs (usually Td but one Tdap)
diphtheria - 3 manifesations
- nasal: discharge (minor)
- laryngeal: obstruction (minor)
3: pharyngeal: gray membrane that continues to grow and block airway (serious)
- mild sore throat, lymphadenopathy, fever malaise
diphtheria - tx
reportable dz
antitoxin: give to anyone w/ possible exposure
remove membrane
ABX: erythromycin (tx until 3 consecutive negative cultures)
- contacts tx with erythromycin for 7 days
pertussis (bordetella pertussis) - characteristics
gram-negative aerobic coccobacillus
respiratory transmission
- incubation of 7-17 days
- most cases in kids <2 yrs (un-vaccinated)
- no lasting immunity (from getting dz or immunization)
- “whooping cough”
pertussis - dx
culture nasopharynx: Bordet-Gengou agar OR PCR
pertussis - prevention
DTap: children < 7; 5 doses
Tdap: older children, adults
- booster every 10 yrs (usually Td but one Tdap)
pertussis - manifestations
3 stages:
- catarrhal: sneezing, anorexia, malaise, hacking cough
- paroxysmal: bursts of rapid coughs follow by “whoop”
- convalescent: 4 wks after onset; dec. in frequency and severity of cough
non-specific lab finding: lymphocytosis (high WBC)
pertussis - tx
erythromycin x 7 days
alternatives: azithromycin, clarithromycin, TMP-SMX
contacts (any person in contact w/in 3 wks of start of cough): same tx
tetanus (clostridium tetani) - characteristics
gram-positive anaerobic rod
found in soil
local inoculation of wounds - spore germinate within wounds
neurotoxin - results in uncontrolled spasms
At risk: elderly, migrant workers, IVDUs
Most due to puncture wounds (stepping on nail)
tetanus - manifestations
progressive:
- pain and tingling at site
- muscle spasms
- stiff jaw, neck, dysphagia, irritability
- painful, toxic convulsions (trismus = lock jaw)
- remain conscious, no sensory deficits or fever
tetanus - treatment
tetanus immune globulin
PLUS: full course of immunization once recovered
tetanus - prophylaxis
includes Tdap or Td and/or immune globulin (TIG)
- depends on clean vs. dirty wound and vaccine hx
salmonella (S enterica) - characteristics
gram-negative facultative anaerobic rod
transmission though fecal-oral route
incubation: 8-48 hrs
sxs: fever, chills, N/V, crampy abd pain, diarrhea (+/- blood) for 3-5 days
salmonella - treatment
self-limited = typically symptomatic care
ABX for malnourished, severely ill, sickle-cell anemia pts
- TMP-SMX, ampicillin, ciprofloxacin
salmonella - bacteremia (population and treatment)
can cause blood infection in immunosuppressed
Sxs: prolonged or recurrent fever
- distal seeding in bones, joints, pleura, pericardium, endocardium, lungs
Tx: fluids and fluoroquinolone
salmonella (S typhi) - characteristics
gram-negative facultative anaerobic rod
transmission through fecal-oral route
sxs: malaise, H/A, cough, fever plateaus (7-10days) then become more ill
- abd pain, distention, constipation or diarrhea (“pea soup”)
- rash: rose spots
salmonella (S typhi) - treatment
fluids
fluoroquinolones
Note: if exposed, can become a carrier (tx: cipro)
shigella (S. sonnei, S. dysenteriae) - characteristics
gram-negative non-spore forming rod
trasmission through fecal-
shigella - manifestations
abrupts onset diarrhea with blood and mucous lower abd cramps tenesmus fever, chills, malaise, anorexia, H/A temporary reactive arthritis (Reiter's)
shigella - diagnosis
stool: WBC, RBC
blood: culture
sigmoidoscopy: inflamed mucosa with punctate lesions and ulcers
shigella - treatment
ABX: fluoroquinolones (Cipro), ceftriaxone, TMP-SMZ
rocky mountain spotted fever (rickettsia rickettsia) - characteristics
bacteria
found in middle/southern Atlantic, Mississippi Valley (not Rocky Mountains)
spread by wood tick, dog tick
late spring or summer
Prevent: avoid ticks
rocky mountain spotted fever - manifestations
progressive:
- fever, chills, H/A, N/V
- restless, insomnia, irritable
- rash (macules to papules): starts at wrists/ankles (includes palms and soles), spreads inward
severe dz: cough, pneumonitis, delirium, lethargy, seizure
rocky mountain spotted fever - labs
thrombocytopenia (low platelets) with hyponatremia (low Na)
- immunohistology and serology to confirm
rocky mountains spotted fever - treatment
doxycycline (ABX): all ages except pregnant
- continue 3 days after fever ends
Pregnant: chloramphenicol
Note: prognosis good with treatment
lyme disease (borrelia burgdorferi) - characteristics
spirochete bacteria
most common tick-borne illness in US (deer tick)
tick must feed for 24-36 hrs to transmit dz (KEY); drops off in 2-4 days
- best removal: fine tipped tweezer
- nymph tick most likely to transmit dz
lyme disease - clinical stages
stage 1: 3-30 days
- flu-like sxs
- erythema migrans (flat or raised), bull’s eye clearing, single or multiple
stage 2: days to weeks (early disseminated)
- fatigue, malaise
- smaller, multiple lesions
- H/A, neck pain
- migratory arthritis
stage 3: mos to yrs (late persistent infection)
- MSK: arthritis, synovitis
lyme - treatment
doxycycline (2-3 wks)
preg: penicillin IM
peds: amoxicillin
Prevention: chemoprophylaxis with doxycycline if met criteria
syphilis (treponema pallidum) - characteristics
spirochete bacteria
ONLY transmitted through sexual contact
syphilis - clinical manifestations
primary: painless chancre (ulcer) - clean lesions
secondary: fever, maculopapular rash (includes palms and soles)
- highly contagious
tertiary: inflammation of CNS (presents in bones, eyes, lungs, GI, etc.)
- neurosyphilis: + CSF, meningovascular, general paresis
- tabes dorsalis: slow degeneration of neural tracts in dorsal columns of spinal cord - loss of proprioception, reflexes, general tone
syphilis - treatment
penicillin (any stage)
syphilis - pregnancy
screen all pregnant patients, repeat in 3rd trimester
- any + serology = tx with penicillin
- goal: prevent congenital syphilis
congenital syphilis
first signs:
- maculopapular rash, mucous membrane patches
- “snuffles” - serious nasal d/c
- hepatosplenomegaly
If untreated:
- interstitial keratitis (blindness), Hutchinson teeth, saddle nose, saber shins, deafness, CNS defect
Treatment: penicillin
cytomegalovirus (CMV) - general info
common infection
most asymptomatic
- virus remains latent and can effect once host becomes immunocompromised
CMV - primary disease (perinatal and healthy host)
perinatal (in utro or breast milk):
- jaundice, hepatosplenomegaly
- microcephaly, CNS calcifications, mental retardation
- motor disability, hearing loss
immunocompetent host:
- fever, malaise
- myalgias, arthralgias
- complications: GI issues, encephalitis, pericarditis, myocarditis, Guillain Barre syndrome
CMV - reactive disease (immunocompromised host - CD4<100)
retinitis: neovascular lesions in back of eye
GI/biliary: esophagitis, IBD-like syndrome
pulmonary: pneumonitis, high mortality
neurologic: encephalitis
CMV - diagnosis
tissue confirmation: “owl’s eye” intracytoplasmic inclusions
atypical lymphs (like EBV)
CMV - treatment
ganciclovir IV +/- focscarnet
maintenance: ganciclovir + foscarnet daily
CMV - prevention
HIV: HAART, ganciclovir or valganciclovir
Post-transplant: antiviral agents and CMV immunoglobulin
epstein barr virus (EBV) - general information
human herpesvirus 4
any age (most common 10-35)
sporadic cases or epidemics (high schools)
transmission: likely saliva
NOTE: associated with many chronic dzs - Burkitt’s lymphoma, nasopharyngeal carcinoma, chronic fatigue, oral hairy leiloplakia, Hodgkin’s, SLE, MS, rheumatoid arthritis
EBV - clinical manifestations
most common: fever, sore throat, malaise, anorexia, myalgias
common: posterior lymphadenopathy, splenomegaly, maculopapular rash (NOTE: 90% if give ampicillin), exudative pharyngitis, soft palate petechiae
less common: hepatitis, gall bladder, mononeuropathy, meningitis, etc.
EBV - labs
heterophil antibodies (monospot)
EBV - treatment
symptomatic, supportive
acyclovir: decrease viral shedding (no effect on course of illness)
steroids: only if
- impending airway obstruction
- hemolytic anemia
- severe thrombocytopenia
EBV - prognosis
95% recover w/o specific tx
fever ends in 10 days; lymphadenopathy and splenomegaly ends in 4 weeks; debility may last 2-3 months
rabies - general information
transmitted from: raccoons, skunks, bats, foxes, coyotes (not bunnies)
incubation 3-7 wks
virus travels along nerves, multiplies in brain, migrates to salivary glands
rabies - manifestations
pain at site, fever, malaise, N/V
CNS stage: relentless progression
- “furious” encpehalitis: delirium, spasm, hydrophobia
- “dumb” paralytic”
- ascending paralysis (looks like guillain barre)
Note: fatal dz
rabies - prevention
immunization of domestic animals
local bite care
prophylaxis: rabies immune globulin and human diploid cell rabies vaccine
rabies - treatment
note: almost ALWAYS fatal - ICU, ventilation, multi-drug approach
HIV (human immunodeficiency virus) - general information
first recognized in 1981
human retrovirus (requires reverse transcriptase for replication)
targets all cells with T4 antigen, primarily CD4 helper lymphocyte
HIV/AIDS - transmission
sexual contact, parenteral exposure, perinatal transmission
HIV - diagnosis
screening:
- ELISA, confirmatory Western blot or HIV antigen assay
- Rapid HIV testing
viral load:
- measures actively replicating virus
CD4 count:
- how well body is fighting virus (CD4<200 = risk of poor outcome = opportunistic infections and malignancies)
Labs: pancytopenia
HIV - clinical manifestations
acute HIV: tough to identify
- flu or EBV-like illness
- persistent lymphadenopathy
HIV disease:
- fever, night swats, weight loss, dementia
- opportunistic infections, malignancies
AIDS - manifestations (indicator conditions)
there are many, including:
- recurrent bacterial pneumonia
- candidiasis of respiratory tract
- Kaposi sarcoma
- wasting syndrome (wt loss, diarrhea, fever > 1 month)
HIV/AIDS - prevention
primary: safe sex, harm reduction, drug rehab, screen blood products
secondary: screening at risk pts, prevent opportunistic infections and malignancies in those infected
post-exposure: counseling, testing now, 6wks, 3mos, 6mos; anti-viral therapy (3 drug combo) - begin w/in 72 hrs for best outcome (continue 4-6 wks)
perinatal: antivirals during pregnancy, L&D, and to newborn; avoid breast feeding
HIV/AIDS - treatment
HAART (antiretroviral therapy) - combo therapy preferred
tx or prevent opportunistic infections and malignancies
goal: suppress viral load
monitor: CD4, viral load, overall pt health status
obstacles: adherence, effectiveness, resistance, adverse effects
anti-HIV drugs - 6 categories and major side effects of each
NRTIs (nucleoside reverse transcriptase inhibitors)
- SEs: anemia, neutropenia, GI distress, hepatitis, pancreatitis
NNRTIs (non-nucleoside reverse transcriptase inhibitors)
- SEs: rash, near manifestations, anxiety
fusion inhibitor
- SEs: injection site pain, pruritis, allergic rx
CCR5 antagonist
- SEs: cough, fatigue, abdominal pain, dizziness
protease inhibitors
- SEs: H/A, GI upset, peripheral paresthesias, renal calculi, depression, arrhythmias, lipid abnormalities
INSTIs (integrase strand transfer inhibitors)
- SEs: H/A, dizziness, nausea, insomnia
combination drugs:
- preferred
helminths - general information (3 categories)
parasites, all hermaphroditic (have both male and female reproductive parts)
3 categories:
- nematodes (roundworms)
- trematodes (flukes)
- tapeworms
helminth infections - manifestations
intestinal infestations (mild to severe) malnutrition, growth disruption skin signs: red, pruritic (hookworm) try to get into blood or lymph systems (can cause lymph obstruction) renal dz, splenic infarction
absenteeism: miss work and school b/c of diarrhea
helminth infections - treatment
albendazole
deworming programs: STOP transmission
malaria - two types to know about
parasite
plasmodium vivax: most common
P falciparum: most deadly
malaria - characteristics
endemic in tropics
1 million deaths/year
most cases in US are imported
anopheles mosquito inoculates human –> sporozoites travel to liver and released into bloodstream and enter RBCs
malaria - clinical manifestations
attacks consist of shaking chill (cold stage), fever (hot stage), and diaphoresis (sweating stage)
- last 4-6 hrs, reoccur every other day or every 3rd day
P falciparum: CNS manifestations and renal insufficiency - poor prognosis
malaria - labs / diagnosis
peripheral smear - fresh blood (look for parasitemia - see them within RBCs)
malaria - treatment
chloroquine
- safe in pregnancy, well tolerated
malaria - prognosis
2-4 weeks uncomplicated, untreated
good prognosis (if treated)
P falciparum: 15% mortality rate despite tx
malaria prevention
chemoprophylaxis: chloroquine, malorone, mefloquine, doxycycline
education / mosquito control: bed nets, screens, clothing, DEET
toxoplasmosis (toxoplasma gondii) - characteristics
only in humans, cats, and birds
80% of primary infections are asymtomatic
cysts: latent form, press indefinately in muscle and nerve tissue
oocysts: passed in feces, remain infective for wks-yrs
toxoplasmosis - transmission
ingest cysts (raw or uncooked meat)
ingest oocysts (food, water, cat littler, soil)
transplacental transmission
toxoplasmosis - 4 clinical syndromes
healthy person: acute, mild, febrile, multi-system (mono-like)
congenital (maternal primary infection during pregnancy): still birth, eye (blindness) or brain damage (either at birth or within a week of birth)
immunocompromised: focal infection, encephalitis (brain), disseminated infection (multi-system)
toxoplasmosis - diagnosis
histology: look for cysts, trophozoites
serology: look for antibodies with ELISA, Western blot, PCR, IgG
CT: ring enhancing lesions (on periphery and multiple vs. lymphoma where lesions are central and single)
toxoplasmosis - treatment
immunocompetent: tx only if severe dz
immunocompromised: pyrimethamine PLUS folic acid
- treat 4-6 wks, then prophylaxis (TMP-SMX, dapsone)
toxoplasmosis - prevention
fully cook meat
protect from cat feces (clean litter box)
screen all pregnant women - if no antibodies, avoid cats
pinworms (enterobius vermicularis) - characteristics
humans only host
fecal-oral trasmission
adult worm in colon, eggs deposit in perianal area (night-time)
pinworms - diagnosis
see at night; scotch tape test (see eggs and worms)
pinworms - treatment
albendazole, mebendazole, pyrantel
treat all household members; repeat tx in 2 weeks
hygiene, linens, etc.
