ID Flashcards
Mycobacterium Avium Complex (MAC) definition, sx, dx, tx
Mycobacterium avium & intracellulare, etc.
Transmission: present in soil & water (not person to person)
Risk Factors:
*underlying pulmonary disease (bronchiectasis, COPD)
*HIV w/ CD4+ ≤50
*sxs rarely occur in immunocompetent pts w/o underlying lung disease
sx
Pulmonary: presents similar to TB
*cough, chest pain, fever, weight loss
*upper lobe infiltrates & cavities
Disseminated: MC seen w/ HIV
*fever of unknown origin (MC)
*sweating, weight loss, fatigue, diarrhea, dyspnea
*RUQ pain, hepatosplenomegaly
Lymphadenitis in children:
*cervical, submandibular, maxillary
dx
*acid fast bacillus staining
*culture
tx
*clarithromycin + ethambutol x12mo (+/- rifampin)
Prophylaxis in HIV pts:
*azithromycin or clarithromycin if CD4+ <50
Mycobacterium Kansasii
*causes TB-like disease
*tx w/ rifampin + ethambutol
Mycobacterium Marinum “Fish Tank Granuloma” definition, sx, dx, tx
Atypical Mycobacterium found in fresh & salt water
Transmission:
*inoculation of a break in the skin barrier w/ exposure to contaminated fresh or salt water, including aquariums, marine organisms, & swimming pools
*occupation hazard of aquarium handlers, marine workers, fisherman, & seafood handlers
sx
Localized cutaneous disease:
*erythematous bluish papule or nodule at the site of trauma that can ulcerate (hx of exposure to non-chlorinated water 2-3wks earlier)
Subsequent lesions may occur along the path of lymphatic drainage over a period of months
dx: culture
tx
*tetracyclines, FQs, macrolides, sulfonamides x4-6wks
Epstein-Barr Virus (Mononucleosis) – HHV4 definition, sx, dx, tx
Infection due to EBV characterized by fever, LAD, & tonsillar pharyngitis
PATHO: EBV infects B cells
Transmission: saliva (known as the kissing disease) esp. ages 15-25
sx
*fever, LAD (esp. posterior cervical)
*tonsillar pharyngitis (may be exudative)
+/- petechiae on hard palate
+/- fatigue, HA, malaise
PE:
*splenomegaly
*rash – seen in ~5% esp. if given ampicillin
dx
Heterophile antibody (Monospot)
Rapid viral capsid antigen test; ↑ LFTs
Peripheral smear: lymphocytosis >5% w/ >10% atypical lymphocytes
tx
Supportive
- rest
- analgesics (acetaminophen, NSAIDs)
- antipyretics
Steroids ONLY if:
- airway obstruction d/t LAD
- hemolytic anemia
- severe thrombocytopenia
AVOID TRAUMA & CONTACT SPORTS 3-4WKS IF SPLENOMEGALY TO PREVENT RUPTURE
Influenza definition, sx, dx, tx
A associated w/ more severe outbreaks than B
Transmission: primarily via airborne respiratory secretions (sneezing, coughing, talking, breathing), contaminated objects
Increased risk:
*age > 65yrs, pregnancy, immunocompromised
*MC seen in children, but >65yrs at highest risk for complications
Complications: pneumonia, respiratory failure, death, meningitis, myocarditis, encephalitis, rhabdomyolysis, kidney failure
sx
ABRUPT ONSET
*HA
*fever, chills
*malaise
*URI sxs
*pharyngitis
*pneumonia
*myalgias: legs & lumbosacral areas
dx
Rapid influenza nasal swab
Viral culture
tx
Mild disease, healthy:
- supportive: acetaminophen, rest, fluids
Oseltamivir
- >65yrs, CVD, pulmonary disease, immunosuppression, chronic liver disease, hemoglobinopathies
Prevention: influenza vaccine
- ADRs: fever, myalgia, irritability
- CI: anaphylaxis to the vaccine, GB within 6wks of a previous vaccine, high fever, infants <6mo
Pertussis (Whooping Cough) definition, sx, dx, tx
Bordetella pertussis (gram -)
Transmission: respiratory droplets
Vaccine: DTaP
*2, 4, 6mo
*15-18mo
*4-6yrs
sx
Catarrhal phase: URI sxs lasting 1-2wks (rhinorrhea, low-grade fevers, sneezing), poor feeding/sleeping
*most contagious
Paroxysmal phase: severe paroxysmal coughing fits w/ inspiratory whooping sound after cough fits
*may have post-tussive emesis; infants may present w/ apnea or cyanosis & often lack characteristic cough/whoop
*lasts 2-6wks
Convalescent phase: residual cough, can last weeks-months
dx
Clinical definition: cough lasting >2wks + ONE of the following (paroxysms of coughing, inspiratory whoop, post-tussive emesis, apnea in infants <1y)
PCR (nasopharyngeal swab)
Culture (gold standard)
CBC: leukocytosis w/ WBC >15,000 w/ absolute lymphocytosis
CXR: perihilar infiltrates, “shaggy right heart border”
tx
Supportive:
*oxygenation, nebulizers, mechanical ventilation
Antibiotics:
*azithromycin, erythromycin, clarithromycin
Infants <6mo: complicated by apnea in 2/3 of pts, superinfection w/ other bacterial pneumonia, seizures, encephalopathy, pulmonary HTN, & death (particularly in infants <2mo)
Enterobiasis *pinworm definition, sx, dx, tx
Enterobius vermicularis (pinworm)
MC helminthic infection in US
Transmission: fecal-oral (school-aged children)
sx
*perianal itching, esp. nocturnal
Severe 🡪 abdominal pain, N/V
dx
(+) Cellophane tape test or pinworm paddle test
*eggs under microscope
tx
*Albendazole, Mebendazole, or Pyrantel
*Pyrantel preferred in pregnancy
Toxoplasmosis *protozoa definition, sx, dx, tx
Toxoplasma gondii
Transmission: soil or cat litter contaminated w/ feline feces
sx
Primary infection: usually asymptomatic infection in immunocompromised pts
*may develop a mono-like illness w/ cervical LAD if symptomatic
Reactivation: triad of encephalitis, chorioretinitis, & intracranial calcification in an AIDS pt w/ CD4+ count <100
dx
ELISA 🡪 anti-toxoplasma IgG antibodies
Neuroimaging (MRI > CT): multiple ring-enhancing lesions
tx
*sulfadiazine + pyrimethamine (w/ folinic acid to prevent folic acid depletion)
Prophylaxis:
*TMP-SMX when CD4+ count ≤100
Lyme Disease definition, sx, dx, tx
Lyme Disease
Borrelia burgdoferi
Transmission: Ixodes scapularis (deer tick)
MC in northeast states
sx
Early localized (3-32d after bite): erythema migrans (red annular lesion w/ central clearing), fever, malaise, HA, myalgias, arthralgias
Early disseminated (3-10wks after bite): multiple erythema migrans lesions, CN palsies (esp. 7, lasts 2-8wks then resolves), fatigue, myalgia, HA, occasionally meningitis (stiff neck) or carditis (AV block)
Late disseminated (months-yrs after bite): monoarticular arthritis of large joint (knee in >90%), CNS involvement including chronic demyelinating encephalitis, polyneuritis, memory problems (rare in children)
dx
EIA, if ⊕ ⇢ western blot to confirm
⊕ = 2/3 IgM bands, 5/10 IgG bands
*IgM peaks @3-6wks, IgG weeks-months later
LP (meningitis): 10-150 WBC/mm3, <10% segmented neutrophils, ⇡ protein, normal glucose
EKG: heart block (pts w/ disseminated)
Joint aspiration: WBC 25,000-80,000/mm3 & ⊕ Lyme PCR of joint fluid
tx
Early localized: doxycycline x14-21d
Early disseminated: doxycycline x21d
*peds: cefuroxime (preferred), erythromycin
Carditis w/ severe/symptomatic AV block:
*ceftriaxone x14-21d
Late disseminated: doxycycline x21-28d
Arthritis unresponsive to PO therapy:
*IV ceftriaxone x28d
Jarisch-Herxheimer Reaction: transient fever, HA, myalgias after therapy is started
Rocky Mountain Spotted Fever definition, sx, dx, tx
Rickettsia rickettsia
Transmission: dog tick (Dermacentor variabilis), wood tick (Dermacentor andersonii), Lone star tick (A. americanum)
Incubation: 2-14d
Duration: typically 1-2wks
sx
Early: high fever, myalgia, HA (w/ photophobia), V/D, abdominal pain
RASH (2-6d after fever onset): begins on ankles/wrists 🡪 trunk (within hours) & palms/soles
*initially blanching, erythematous, macular
*becomes petechial then hemorrhagic
Other organ systems: vascular leak causing edema, hypovolemia, & hypotension; conjunctivitis, splenomegaly, pneumonitis, meningitis, confusion
dx
Clinical: fever + rash + hx of tick exposure
Labs (vasculitis): thrombocytopenia, ⇣ Na, mild leukopenia, proteinuria, mildly abnormal LFTs, hypoalbuminemia, hematuria
CSF pleocytosis common
Serology: indirect fluorescent or latex agglutination antibody (not ⊕ until 7-10d after onset); PCR from whole blood/skin biopsies (⊕ 1st week of illness)
tx
SUPPORTIVE; anticipate complications (hypotension, thrombocytopenia, DIC, hypoalbuminemia, hyponatremia)
DOXYCYCLINE x7-10d; alt – chloramphenicol
*continue until pt is afebrile x3d
TORCH syndrome definition, sx, dx, tx
TORCH SYNDROME: hemolytic anemia, thrombocytopenia, hepatosplenomegaly, & brain calcifications caused by a group of viruses when acquired during pregnancy
Hemolytic anemia results in extramedullary hematopoiesis (specifically of the liver & spleen) 🡪 hepatosplenomegaly & neonatal jaundice
Thrombocytopenia (↓ platelets) 🡪 petechiae (MC on face)
Brain: calcifications (can cause neonatal seizures), microcephaly
EXTREMELY RARE because mom must become exposed & infected for the first time during pregnancy, before 20wks gestation
Toxoplasmosis, Other = syphilis, Rubella, CMV, HSV
Congenital Toxoplasmosis definition, sx, dx, tx
Toxoplasma Gondii *protozoan
PATHO: *CAT LITTER, raw meat
↑ transmission risk w/ ↑ gestational age
sx
Mom: +/- flu-like sxs, LAD
Congenital Triad:
*hydrocephalus 🡪 macrocephaly
*chorioretinitis (MC)
*intracranial calcifications
dx
Mom: (+) Toxoplasma-IgG & IgM
Prenatal:
U/S: ventriculomegaly (hydrocephalus), intracranial calcifications (hyperechoic)
(+) DNA PCR of amniotic fluid
MRI (postnatal): ring-enhancing lesions
Confirmed DX:
(+) IgG w/ (+) IgM (>5do) &/or IgA (>10do)
(+) CSF PCR
(+) IgG >12mo
tx
*infants diagnosed prenatally treated postnatally
pyrimethamine + sulfadiazine
+ folinic acid (leucovorin)
Congenital Syphilis definition, sx, dx, tx
T. pallidum
*ALL PREGNANT PTS SCREENED @1ST VISIT
Highest risk of transmission in primary & secondary disease
sx
MC: hydrops fetalis 🡪 stillbirth
Early (<2yo): hepatosplenomegaly, LAD, syphilitic rhinitis (“snuffles”), maculopapular rash (+palms/soles), pseudoparalysis, thrombocytopenia, anemia, syphilitic leptomeningitis
Late (>2yo): frontal bossing, saddle nose, short maxilla, chorioretinitis, interstitial keratitis, sensorineural deafness, Hutchinson teeth, Saber shins (tibia bowing)
dx
Mom:
(+) nontreponemal: RPR, VDRL
(+) treponemal: FTA-ABS
Baby:
(+) RPR or VDRL of umbilical cord blood
(+) FTA-ABS of body fluids, placenta, or cord
Darkfield microscopy: spirochetes
tx
Mom: ALWAYS treated w/ PCN even if allergic
Baby: IV penicillin G x10d
Once RPR is (+), it will ALWAYS be (+)
*if LOW titer (1:2), previous tx adequate
*if HIGH titer (1:1100), mom treated AGAIN
Congenital Rubella Syndrome definition, sx, dx, tx
Rubella virus, togavirus family
Transmission: respiratory droplets
*most likely in 1st or 3rd TM
*TERATOGENIC, esp. in 1st TM
sx
Mom: fever + rash (starts on face, then trunk & limbs)
MC S/SXS: sensorineural deafness, cataracts, cardiac disease
*cardiac: PDA (machine murmur), peripheral pulmonary stenosis
S/SXS: meningoencephalitis, radiolucent bone disease, intellectual disability
dx
Mom: ELISA 🡪 rubella-specific IgG & IgM
*test within 7-10d of rash onset, repeat 2-3wks
Prenatal: PCR on chorionic villous sample
Confirmed DX:
(+) rubella-specific IgG or IgM
(+) viral culture of nasopharyngeal, blood
(+) rubella virus RNA by PCR
tx
*supportive; infant considered contagious for 1y
MMR vaccine = live attenuated
*CONTRAINDICATED IN PREGNANCY
Congenital Cytomegalovirus definition, sx, dx, tx
CMV, HHV-5
Transmission more likely in 3rd TM
sx
Mom: asymptomatic
S/SXS: microcephaly w/ periventricular calcifications
*leading cause of deafness (sensorineural loss) & learning disability
dx
Prenatal: viral culture, CMV DNA in amniotic fluid
*U/S: periventricular calcifications
0-3wks: (+) CMV via viral culture of urine or saliva
>3wks: (+) PCR of dried blood spot
tx
*IV ganciclovir OR PO valganciclovir
*TX NOT RECOMMENDED IF ASYMPTOMATIC
Congenital Herpes Simplex definition, sx, dx, tx
Congenital Herpes Simplex
HSV-2 (genital)
Majority of neonatal HSV infection are acquired perinatally, via an infected maternal genital tract
sx
*Congenital HSV divided into 3 classifications
Localized skin, eye, & mouth (SEM):
*characteristic vesicular lesions
*conjunctivitis, excessive tearing
*mouth, palate, & tongue ulcers
CNS w/ or w/o SEM: seizures, lethargy, irritability, tremors, poor feeding, +/- skin lesions
Disseminated: sepsis, hepatitis, respiratory distress, DIC, +/- skin lesions/CNS involvement
dx
*viral culture, HSV DNA via PCR
*viral antigens via DFA & EIA
(+) HSV Ab = past infection
tx
(+) HSV Ab, Ø genital HSV: normal pregnancy
h/o genital HSV: start acyclovir @36wks
Active genital HSV: CESAREAN!!
Active genital + Ø cesarean: IV acyclovir to BABY
SEM: IV acyclovir x14d
CNS or disseminated: IV acyclovir x21d
F/U: PO acyclovir TID x6mo
