Infectious Diseases Flashcards
Evaluation of suspected ventilator-associated pneumonia
- Suspect for Ventilator-associated pneumonia (VAP)
- abnormal chest X-ray - Lower respiratory endotracheal tube sample
- culture
- microscopy - Empiric antibiotics
- gram (+)
- antipseudomonal & gram (-)
- MARSA (methicillin-resistance Staph. aureus)
—-
3.1 negative culture:
- discontinue antibiotics + evaluate for other causes
3.2 positive culture & clinical improvement
- narrow antibiotics (according to the culture result)
3.3. Positive culture without clinical improvement:
- likely VAP
- Consider changing antibiotics
- assess for VAP complication ( abscess, empyema)
- consider evaluating for other causes
Ventilator-associated pneumonia
Feature:
- occurs after 48 hours of endotracheal tube incubation
- associated with:
1. Gram (-) bacilli ( pseudomonas, E.coli, Klebsiella)
2. Gram (+) cocci ( MRSA, Streptococcus)
Signs:
- fever
- leukocytosis ( increase WBC)
- purulent secretion
- difficulty with ventilation ( increase RR, decrease Tidal volume)
Meningococcal meningitis
Epidemiology:
- Neisseria Meningitis
- most common in young children & young adult
Feature:
- initially: non-specific fever, headache, vomiting, myalgia, sore throat
- within 12-24 hours: petechiae/purpura, meningeal signs (stiff neck), altered mental status
Diagnosis:
-blood culture (before starting antibiotics)
- lumbar puncture
Treatment:
- ceftriaxone ( ± vancomycin for coverage of PRSP)
-treatment should not be delayed for lumbar puncture
Complication:
- shock
- DIC
- adrenal hemorrhage
Prevention:
- droplet precautions
- chemoprophylaxis ( Rifampin, ciprofloxacin, or ceftriaxone) —> for close contacts
Tularemia ( rabbit fever, or deer fly fever )
- typically attacks the skin, eyes, lymph nodes and lungs
- infection with: Francisella Tularensis
LEAD TO:
- unilateral conjunctivitis with ipsilateral pre-auricular lymphadenopathy ( parinaud oculoglandular syndrome) —-> this is also seen with Bartonella henselae (catscratch), & herpes simplex virus
Epidemiology:
- transmission from:
1. Wild animals ( hare, rabbit) hunting
2. Tick/mosquito bite
3. Bioterrorism agent
Feature:
1. Nonspecific symptoms ( fever, malaise)
2. Ulcero-glandular disease ( tender lymphadenopathy)
3. Pneumonia
Microbiology:
- poorly staining, gram (-) coccobacillus
- most strains require cysteine for growth
- evade most immune defenses & replicate within macrophages/ neutrophils
Adenovirus
Lead to:
- pneumonia
-regional lymphadenopathy
-Conjunctivitis (minimal or no purulence)
Candida Albican
- seen in:
1. People with compromised immunity ( prolonged neutropenia)
2. Recent eye trauma or surgery
3. Indwelling central catheters
4. Not seen in healthy people
Yersinia Pestis
- transmitted by fleas from rodents & wild/domestic animals
- exposure can occur from hunting/trapping
- lead to very painful suppurative lymphadenitis
Entamoeba histolytica ( Protozoal infestation )
Risk factors:
- resource limited regions (contaminated food/water)
Clinical:
- prolonged blood/mucoid diarrhea
- RUQ pain + fever
- complication: pleural effusion + rupture to peritoneum/pleural space
—> dysentery: abdominal pain + diarrhea + bloody stools
Diagnosis:
- stool PCR antigen
Treatment:
- Metronidazole or tinidazole
PLUS
- intraluminal antibiotics (paramomycin)
Creutzfeldt-Jackob (Mad Cow disease) ( prion)
Hx:
- rapidly progressive dementia
- handling brain (autopsy)
PE:
- ataxia
- cerebellar dysfunction
- myoclonic jerks
Etiology:
- ingestion or contact of infected brain or cattle causes brain shrinkage & deterioration
- transmitted by: surgical instrument, EEG electrodes, corneal transplantation, dura mater graft, human pituitary hormones
Epidemiology:
- most common prion disease
- rare
- medical examiner
- forensic pathologist
- mortician
DX:
- diagnosis of exclusion
TX:
- death within 8 months
- supportive care
Cryptococcal
(Fungal disease)
(More neurological symptoms)
Hx:
- neurologic ( fever, headache)
- respiratory ( non-productive cough, pleuritic chest pain)
PE:
- neurologic ( papilledema, nuchal rigidity)
-respiratory ( rales )
- pustular rash
Etiology:
- inhaled spores of cryptococcus neoforman yeast In birds & bat feces
- causes meningitis (most common presentation )
- or pulmonary disorder
Epidemiology:
- immunocompromised
- farmers
- demotition Crew
- pacific coast (colonize in eucalyptus trees)
Dx:
- lumbar puncture (if neurologic)
- sputum culture (if respiratory)
- cryptococcal antibody titer
- lesion biopsy
Tx:
- oral antifungal ( Amphotericin B)
Histoplasmosis
(Fungal disease)
(More respiratory symptoms)
Hx:
- asymptomatic (90%) (if solve resolve within 4 weeks)
- night sweat
- mainly respiratory symptoms ( dyspnea, dry or productive cough, hemoptysis)
PE:
- maculopapular rash
Etiology:
- Histoplasma Capsulatum Fungus in soil with bird or bat feces
- is inhaled & grows into yeast
Epidemiology:
- ohio, Missouri, Mississippi River Valley
- ( ideal soil composition & moisture)
- immunocompromised
Dx:
- sputum + blood cultures
- antibody titer
- chest X-ray ( hilar masses)
Tx:
- most cases self resolve within 4 weeks
- if longer than 4 weeks, consider Amphotericin B
Pneumocystis Jirovecii Pneumonia (PJP)
(Fungal disease)
Hx:
- weight loss, dyspnea, severe dry cough (sputum is too thick to be expectorated)
PE:
- tachypnea, fever, decrease oxygen saturation (SPO2)
Etiology:
- fungal pneumocystitis jirovecii spores ( formerly called, Pneumocystitis Carinii, but this species was found to only infect rats)
Epidemiology:
- most common infection in AIDS & immunocompromised
Dx:
- sputum culture
- positive Beta -D- Glucan ( assay detects fungal cell wall)
- Chest X-ray: diffused perihilar infiltrates
- CT: ground glass
Tx:
- TMP/SMX (Bactrim)
- steroids
- mortality 20%
Pinworms (helminth)
(Helminthic/worm disease)
Hx:
- nocturnal perianal pruritus
PE:
- Anal excoriations
- less than 1 cm perianal white worms
Etiology:
- Enterobius Vermicularis
- fecal-oral route
- female lay eggs outside of anus at night & cause itching
Epidemiology:
- most common Helminth infection
- 30% of children ages (5-14)
- daycare
- crowded living situation
Dx:
- scotch tape test (over anus shows eggs or worms)
Tx:
- mebendazole (vermox)
- albendazole ( albenza)
- treat household contacts ( clean linens in hot water, frequent hand wash) —> highly contagious
Helminth intestinal infestation
Hookworm:
- Ancylostoma duodenale, Necator Americanus
- eggs in animal feces/soil absorbed through skin, walking barefoot
- reside in intestine
- lead to iron deficiency anemia
Tapeworm:
- raw or uncooked pork (Taenia Solium), Beef (Taenia Saginata), rarely fish (Taenia latem)
- reside in intestine
- cause weight loss & malnutrition
- treat with: praziquantel
Ascarids:
- Ascaris Lumbricoides
- Contaminated soil on food/hands, ingested
- roundworms grow & multiply in intestine
-cause malnutrition & intestinal obstruction
Flukes:
- Clonorchis sinensis, opisthorchis viverrini
- contaminated water —> burrow in skin
- undercooked seafood
- reside in intestine, blood, liver, lung
Trichinosis:
- Trichinella worms ( Trichinella spiralis)
- raw or undercooked pork
- encapsulates in muscle & brain tissue ( difficult to treat)
Helminth Infestation
Filariasis (Elephantiasis)
- Wuchereria Bancrofti (most common)
- Filariid worms transmitted by mosquitos
- reside in lymphatic system, skin
- causes lymphatic pooling, skin breakdown
Guina worm ( Dracunculiasis)
- Dracunculus medinensis
- contaminated water
- reside in skin, head will emerge
- removed small amount at a time, breakage can cause secondary infection
Loa loa worm (loiasis)
- filariid worm transmitted by bite of Chrysops Fly (mango or deer fly)
- migrates to and reside in eye
Tropical viral fevers ( Dengue, Yellow )
(Viral diseases)
Hx:
- 80% of Dengue fever are asymptomatic
- Myalgia + malaise + headache
PE:
- both have fever & petechial rash
1. Dengue: usually mild mucosal bleeding
2. Yellow: 15% develop jaundice (yellow), mucosal & GI bleed —> hypotension —> death
Etiology:
- both are spread by Aedes mosquito, incubation of 1 week
1. Dengue: dengue virus, 5% develop Hemorrhagic GI bleeding
2. Yellow: Flavivirus, 15% develop liver failure
Epidemiology:
- Latin America, Southeast Asia, Africa
Dx:
- CBC ( neutropenia, thrombocytopenia)
- PCR
- ELISA
TX:
- IV fluid
- Acetaminophen
- Fresh frozen plasma ( if bleed)
- prevent with vaccine
- Dengue: resolves in 10 days; Mortality with GI bleeding is 25%, without is 1%
- Yellow: resolves in 5 days. Mortality with Jaundice 20-50%, without is 7%
Ebola Virus ( viral hemorrhagic fever)
( viral disease)
Hx:
- headache, diarrhea, vomiting, abdominal pain, travel to endemic area
PE:
- High fever, rash, ciliary injection, internal & external bleeding.
- in lateral stages, liver & renal failure, bleeding in eyes, ears, nose
Etiology:
- infected primate ( hunting & eating)
- virus transmitted through any body fluid
- incubation 2-21 days
Epidemiology:
- Africa, healthcare worker
DX:
- CBC ( thrombocytopenia)
- coagulation panel ( prolonged PT, PTT, Bleeding time)
- PCR
- ELISA
TX:
- IV Fluid
- oxygen
- supportive
- 50-90% mortality within 6-16 days of symptoms onset
- Remdesivir is experimental
Zika virus
(Viral diseases)
Hx:
- 80% asymptomatic
- arthralgia, headache, travel to endemic area within 2 weeks
PE:
- rash, fever
Etiology:
- flavivirus transmitted by Aede mosquito
- sexually transmitted
Epidemiology:
- Africa, Southeast Asia, South America, Virgin Island, Puerto Rico
Dx:
- urine PCR
TX:
- self resolved (7 days)
- teratogenic if pregnant (microcephaly, eye deformity)
Hantavirus
(Viral disease)
Hx:
- prodrome (3-5 days of GI): vomiting, diarrhea, abdominal pain
- cardiopulmonary phase (1-2 days of respiratory): dyspnea, dry cough
PE:
- Rales, dehydration ( sunken eyes, decreased skin turgor, dry mucous membrane)
Etiology:
- inhaled Sin Nombre Virus in rodent waste
Epidemiology:
- arid, dusty climate (desert)
Dx:
- smear ( atypical lymphocytosis)
- PCR
- ELISA ( elevated IgM & IgG)
TX:
- supportive
- ventilation
Infectious Mononucleosis
(Viral disease)
Hx:
- extreme fatigue, pharyngitis, sharing drinks, kissing
PE:
- cervical lymphadenopathy, tonsillar exudates, splenomegaly, fever, jaundice, faint transient rash, petechiae on soft palate.
Etiology:
- Epstein- Barr Virus infection of B lymphocyte
Epidemiology:
- young adult
Dx:
- CBC (leukocytosis)
- smear (atypical lymphocytes)
- heterophiles (mono-spot)
- screening test
- elevated EBV IgM
Tx:
- NSAIDS & rest
- self resolve 10 days- 3 months
- no contact sport ( lead to splenic rupture)
- may get rash if given Penicillin antibiotics ( amoxicillin)
Cytomegalovirus
(Viral disease)
Hx:
- flu-like symptoms + sore throat
PE:
- fever, cervical lymphadenopathy
Etiology:
- HHV5 transmitted by bodily fluid
- in immunocompromised: can cause hepatitis, retinitis, colitis, pneumonitis, esophagitis, encephalitis
Epidemiology:
- 90% of human can get it during lifetime
Dx:
- smear ( Owl’s eye infected cells)
- PCR
-ELISA
TX:
- IVIG ( if severe)
- antiviral in immunocompromised (reduce mortality; ganciclovir; foscarnet)
- teratogenic if pregnant ( cognitive & motor defects)
HIV & AIDS
(Viral disease)
Hx:
- unprotected sex ( #1 receptive anal), multiple partners, other STDs, IV drug use, transfusion
- prodrome ( 2-4 weeks): flu-like illness, truncal rash, neuropathy, diarrhea
- clinical latency (3-20 years): fever, weight loss, lymphadenopathy
- If untreated, 50% will develop AIDS 10 years after exposure: opportunistic infection ( Kaposi sarcoma, Burkitt lymphoma, thrush, PJP, TB, toxoplasmosis, shingles, dementia).
Etiology:
- HIV-1 (common), HIV-2 (rare)
- blood borne ( mother to child, IV needle, needle stick, genital ulcers, rough sex)
Epidemiology:
- Sub-saharan Africa
- men have sex with men ( anal sex)
- IV drug users
Dx:
- PCR
-ELISA
- antibody test
- CD4 T cell count ( CD4 < 200 = AIDS)
TX:
- highly active antiretroviral therapy (HAART) = normal life expectancy ( without it = 10 years)
- condom use, antiviral vaginal gel
- pre-exposure prophylaxis: tenofovir/ emtricitabine
- post-exposure (48-72 hours): 3 antiviral drug combo
Rabies
( viral disease)
Hx:
- aggressive animal bite patient 1-3 months before symptoms.
- triads ( paresthesia, pain, intense itching at bite site)
- malaise, headache, fever, insomnia
PE:
- furious type (80%): agitation, delirium, hydrophobia & aerophobia ( attempting to drink or having air blown in the face cause pharyngeal spasms), excessive salivation, convulsion, autonomic dysfunction —> arrhythmia, hypotension —> death
- paralytic type (20%): priapism, anisocoria, facial palsy, progressive paralysis —> death
Etiology:
- CNS- acting Lyssavirus
- dog/cat, bat, skunk, coyote, wolf…
Epidemiology:
- 2 human death annually
Dx:
- nuchal skin biopsy of patient ( rabies virus in cutaneous nerve)
- test questionable animal
- salivary PCR
TX:
- debride wound,
- rabies vaccine at bite site
- IVIG
- 100% mortality due to respiratory failure within 1 week of emergence of neurologic symptoms —> prevent with vaccine
Influenza
( viral disease)
Hx:
- myalgia, fever/chills, headache, sinus pressure, fatigue, dry cough
- exposure to sick contact, no flu shot
PE:
- ill appearing, fever, clear fluid behind tympanic membrane, pharyngeal erythema ( post-nasal drip)
Etiology:
- Type A: severe, peak Nov/Dec
- type B: mild, peak Jan/Feb
- H1N1 ( swine flu): severe variant of type A
Epidemiology:
- highly contagious, common, may lead to pneumonia
Dx:
- nasopharyngeal swab rapid flu test
- PCR for H1N1
TX:
- flu vaccine ( prevent)
- inactivated (IM) shot for older than 6 months & pregnant women.
- live-attenuated for ages 2-49
- may cause flu-like symptoms & injection site reaction.
-Within 48 hours of symptoms onset: oseltamivir, zanamivir