ID Flashcards
Nocardia
gram positive, partially acid-fast, filamentous, branching rods
systemic sxs, lung nodules, brain abscess (seizures), skin findings
tx - bactrim
- add carbapenem when brain is involved
- 6-12 mo
can be confused for TB
- TB - acid fast rods that DONT gram stain
- isoniazid, rifampin, ethambutol
Actinomyces - another gram pos filamentous rod
- anaerobic
- sulfur granules
- cervicofacial infections
clinda
anaerobes and gram pos
pulmonary abscesses due to aspiration pneumonia
histoplasmosis
disseminated histoplasmosis - CD4 count < 100
- midwest and central US, soil (bat or bird droppings, cavingf), dose related, immunocompromised
sxs - systemic
- pulm - cough, dyspnea,
- mucocutaneous lesions
- reticuloendothelial - LAD, HSM
labs - pancytopenia (due to bone marrow infiltration), transaminitis, elevated LDH and ferritin
- CXR - reticulonodular or interstitial infiltrate (because lungs are the portal of entry), bilateral hilar LAD, granulomas with budding yeasts
get - urine Histoplasma antigen, serology, culture (4-6 wks)
tx
- most cases resolve spontaneously
- ampho B for 1-2 wks
- itraconazole for 1 yr thereafter
- AND consider all pts who develop this for antiretroviral therapy
hep C
chronic hep C - asx or non-specific sxs
- elevated tranaminases - but normal in 1/3 of pts
- 20% progress to cirrhosis
- HCC
extrahepatic manifestation - mixed cryoglobulinemia syndrome, membranoproliferative GN, porphyria cutanea tarda (recurrent blistering with trauma or sun exposure, blisters will scar), lichen planus
porphyria cutanea tarda - STRONGLY linked to HCV
- dx supported by plasma and urine porphyrins
- tx with serial phlebotomy or hydroxychloroquine
A1AT
emphysema, chronic hepatitis, cirrhosis, and panniculitis
panniculitis - painful, erythematous nodules and plaques on thighs or buttocks
S pneumo
most common cause of community acquired bacterial meningitis
- headache, fever, nuchal rigidity, AMS
- LP - high opening pressure (>350), neutrophilic leukocytosis (>1000)
- tx = cephalosporin (3), vanc, dexamethasone
- -> add amp for pts >50 or immunocompromised due to increased risk of Listeria
can have concurrent pneumococcal PNA
meningitis
S pneumo - 70%
N menin - 12%
others - H flu, listeria
N menin - esp in adolescents
- meningitis + myalgias, petechial/purpuric rash
- complications - DIC, adrenal hemorrhage, shock
- tx - ceftriaxone and vanc, glucocorticoids are NOT helpful
- mortality >15% even with appropriate tx
- ppx for contacts - rifampin, cipro, ceftriaxone
IV cef and vanc = empiric tx for bacterial meningitis
HIV
BRAIN
cryptococcal meningitis - subacute
- increased ICP sxs, elevated opening pressure on spinal tap
GI
odynophagia and dysphagia
- esophagitis, most pts will also have oral thrush - Candida, fluconazole, EGD if no improvement
- severe sxs –> EGD –> HSV, CMV
- -> white plaques - Candida - fluconazole
- -> linera ulcers - CMV (intranuclear and intracytoplasmic inclusions) - ganciclovir
- -> vesicles - HSV (ballooning degeneration, eosinophilic intranuclear inclusions) - acyclovir
- -> aphthous ulcers (non-infectious) - treat symptomatically, prednisone
LUNGS
MAC - occurs CD4 < 50, all pts with this level of CD4 count should receive azithro ppx
- fever, cough, diarrhea
- splenomegaly, elevated alk phos
PCP - CD4 < 200
- indolent (HIV), acute respiratory failure (immunocompromised)
- fever, dry cough, decreased PaO2
- elevated LDH, diffuse reticular infiltrates
- sputum culture and BAL to id org
- tx - bactrim and added prednisone if PaO2 is low
- ppx - bactrim (pentamidine if pt cant tolerate bactrim) and HAART
- -> organ tx pts have to also be prophylaxed - will be d/c 6-12 mo after transplant
SCREENING
- one time screen - age 15-65 regardless of sxs (and younger/older if at risk), tx for TB or other STD
- annual - IVDA, MSM, sex worker, partner habits, homeless/incarcerated
- additional screening - pregnancy, occupational exposure, new STD sxs, (suggested prior to any new sexual relationship)
post-exposure ppx - <0.5% risk after needlestick
- high risk contact - exposure of mucocutaneous surfaces to blood or bloody secretions or pt has risk factors for HIV
- low risk contact - exposure to secretions other secretions
- immediate HIV testing and f/u serology at 6 wks, 3 mo, and 6 mo
- urgent start 3 drug regimen for 1 mo - two NRTIs (tenofovir, emtricitabine) + other agent (raltegravir)
pyelonephritis
tx for 7-14d
uncomplicated
- healthy, not pregnant, E coli
- tx - oral FQ, bactrim
- IV abx if vomiting, elderly, or septic
complicated - DM, obstruction, renal failure, immunosuppression, hospital-acquired
- increased risk of abx failure
- tx - IV FQ, AG, extended-spectrum b-lactam
- after 48hrs of sx improvement - most pts can be switched to culture-guided oral abx
diabetic infections
FOOT
additional RFs - poor glycemic control, neuropathy, PAD
suspect deeper infection in pts with long-standing wound s (1-2 wks), systemic sxs, and ulcer > 2cm, elevated ESR
- polymicrobial infection that has spread by contiguous spread
- tx empirically - pip-tazo + vanc
MUCORMYCOSIS = fungus, hyphae
- risk factors - DM (DKA), heme malignancy, solid organ/stem cell transplant
- necrotic invasion of palate, orbit, and brain
- dx - sinus endoscopy with bx and culture
- tx - surgical debridement and ampho B
rabies
px - motor weakness, paresthesia, encephalitis –> coma and death
post-exposure ppx - spread by mammals
- high risk wild animal (bat, raccoon, skunk, fox, coyote) - start PEP if animal is rabies pos or if animal is unavailalbe
- low risk wild animal - nothing
- pet - quarantine and observe animal for 10d, no PEP if animal is healthy, start PEP if animal is not available
- livestock or unknown wild animal - contact public health dept
- summary - DONT treat unnecessarily (if you can figure out if the animal has rabies, do that first
- -> why? - because rabies incubation lasts several mo, PEP effective at any point during that time
HBV and serology
SEROLOGY:
acute
- window - anti-core IgM (window because it is the period where HBsAg has disappeared but HBsAb has not yet appeared)
- recovery - antibodies (IgG core, anti-HBs, anti-HBe)
chronic HBV carrier - pos HBsAg and IgG anti-core
- infected during perinatal period - 100% progression to chronic HBV
- kids age 1-5 - 30-50% will progress to chronic infection
- adults - only 5% progress to chronic infection
acute flare of chronic - will have DNA
vaccination - only anti-HBs
immune due to natural HBV infection - pos anti-HBs and IgG anti-HBc
HBe antigen is an indicator of infectivity
HBsAg present during active infection - early phase, chronic HBV carrier
SCREENING: blood transfusions before 1990s
- HBV transmitted by blood, boners, babies
(-HCV - blood)
disseminated gonococcal infection
monoarthritis and/or triad: tenosynovitis, dermatitis (pustules, papules), polyarthralgias (smaller joints, wrists, ankles)
dx - blood cultures (may be NEG, gonorrhea is very slow growing), synovial fluid ana lysis, NAAT of joint aspirate and urethra…
tx - IV ceftriaxone –> oral cefixime when clinically improved
- empiric azithro or doxy for concomitant chlamydial
infective endocarditis
Duke criteria - need 2 major or 1 major + 3 minor
major:
- pos blood culture - s viridans, s aureus, enterococcus
- echo showing a valvular vegetation
minor criteria: IVDA, temp, embolic, etc.
most common sx- fever and murmur
- IF r-sided disease (tricuspid valve involvement, IVDA) - will not have HF or murmur as it is a low pressure system
vascular sxs
- systemic septic embolic (esp to lung, can be cavitary in nature, sx will be pleuritic CP and dyspnea), mycotic aneurysm, Janeway lesions (non-tender)
immunologic phenomena
- Osler nodes (painful, fingertips and toes)
- Roth spots - hemorrhagic lesions in retina
- pos RF
- immune complex mediated GN - hematuria, red cell casts
get blood cultures and echo
Parvo B19
malar rash + flu-like sxs
syphilis
primary - painless chancre + mild inguinal LAD
secondary
- diffuse maculopapular lesions, LAD
tertiary - CV, gummas
latent - axs
tx - penicillin (first-line), doxy is alternate (desensitization is costly, time consuming, and not worth it when there is another alternative)
- same treatment regardless of stage of dz - increase doses/duration depending on dose
- RPR (non-treponemal titers) at time of tx –> repeat titers at 6-12 mo after tx initiation
TB
px
- fever, hemoptysis, weight loss
- disseminated - miliary TB
- reactivation dz - apical infiltrates
who to treat by PPD/IFN quantiferon
>5mm - HIGH RISK, HIV pos, recent contacts of known TB, CXR findings, organ transplant recipients and other immunosuppressed pts
>10 mm - immigrated 5 yrs ago, IVDA, residents/employees of high-risk setting, mycobacteria lab personnel, high risk for Tb reactivation (DM, prolonged corticosteroid, leukemia, ESRD, chronic malabsorption syndromes), kids < 4yo
>15mm healthy
- treat with isoniazid + pyridoxine
- pts with HIV and CD4 <200 may have false negative PPDs - retest these pts after starting HAART
TREATMENTS
latent - isoniazid - mild-severe hepatitis
- 10-20% of pts experience mild, subclinical hepatic injury, self-limited, continue INH
- risk of developing severe hepatotox is 2.6% for those who drink alcohol daily, have liver dz, or are 50+
- pyridoxine (B6) is added to prevent isoniazid-induced peripheral neuropathy (stocking-glove) - isoniazid binds pyridoxine and results in its renal excretion (most pts have sufficient stores but pts with malnourishment, pregnancy, or certain comorbid illness can develop deficiency)
- isoniazid tox - p. neuropathy, hepatotox, sideroblastic anemia
active
- RIPE for 2 mo
BCG vaccine - given in countries with high incidence, to prevent miliary disease and TB meningitis
hepatic cysts/lesions
hydatid cyst - Echinoccus, dogs
- unilocular (typically single) cystic lesions (in any organ, lung, muscle, bone)
- eggshell calcification
- surgical resection + albendazole
- risk of anaphylactic shock if contents of cyst spill
amebic liver abscess -will also have systemic sxs
- 1) intestinal amebiasis
- 2) fever, RUQ pain in 1-2 weeks
pyogenic liver abscess - generally follow surgery, GI infection, acute appendicitis
- extreme pain, high fevers, leukocytosis
simple hepatic cysts - congenital, mass lesion/obstructive sxs
cysticercosis
Taenia
cysts in brain or msucle
Legionella
Legionella - gram negative rod that stains poorly because it is intracellular
contaminated water - in hospital, travel (cruise, hotel)
px - high fever ~39, bradycardia (relative to high fever), GI upset and delayed pulm sxs
- can have hepatic dysfuntion and hematuria & proteinuria
dx - hyponatremia, lobar infiltrate, sputum stain will show PMNs (few-no orgs)
- urine legionella antigen
- tx - FQ (or macrolides)
augmentin
sinusitis, otitis media, human bite wounds
- note on human bites - debridement is often necessary, wounds left to heal by secondary intention
bugs - H flu and Moraxella
pneumonia
S pneumo
flu
- URI/LRI
- adults at high risk for flu complications (namely post-bacterial PNA or PNA due to direct viral injury) - 65+, pregnant, chronic illness, immunosuppression, morbid obesity, NA, nursing home residents
- for influenza PNA - will see bilateral, diffuse interstitial infiltrates, give supp O2 and osteltamivir
- post-viral bac PNA - S pneumo, S aureus, less commonly Pseudomonas
Mycoplasma pneumonia
- respiratory droplets, close quarters, fall or winter
- indolent, persistent dry cough, pharyngitis, macular/vesicular rash
- dx - normal WBC, hemolytic anemia (subclinical), interstitial infiltrate, pleural effusion
- tx - macrolide
Treatments:
- CAP - ceftriaxone + azithro
- HAP - vanc + pip-tazo
C diff colitis
consider even in a pt with unexplained leukocytosis (and no diarrhea)
abx implicated - clinda, FQs, penicillins, and cephalosporins
- PPIs change colonic microbiome - increases risk of C diff proliferation (note the spores are acid resistant)
- C diff carriage is 8-15% and extensive proliferation is required to reach exotoxin levels that are pathogenic
get stool studies (PCR for toxin) - high sensitivity and specificity
- pt with negative studies may require sigmoidoscopy or colonoscopy with bx
- bacterial toxins –> apoptosis of colonic cells, loss of tight junctions
tx with oral metro or vanc
mild-mod = WBC < 15K, Cr < 1.5x baseline
- metro
severe = WBC > 15K, Cr > 1.5x baseline, serum albumin <3 g/dl
- oral vanc - if pt has an ileus –> add IV metro and switch to rectal vanc
- if pt develops WBC > 20K, lactate >2.2, toxic megacolon, or severe ileus –> subtotal colectomy or diverting loop ileostomy with colonic lavage
fidaxomicin can also be used
note: IV vanc is not excreted into the colon (that is why it is not used)
neutropenic fever
neutropenia
- abs is <1500
- severe is <500
pts who are on chemo
- disruption of skin and mucosal barrier –> mucositis and bacterial translocation, usually by gram negative orgs like pseudomonas
- tx - pip-tazo (or cefepime, mero)
add an antifungal if pt has not responded to abx in 4-7d
Moraxella catarrhalis
otitis media (kids)
Guillain Barre
1) paresthesias of toes and fingertips
2) ascending motor weakness
hep A
fecal-oral, international travelers
fever, N&V, abd pain –> jaundice, pruritis
tender hepatomegaly and transaminitis in the 1000s
dx - anti-HAV IgM
tx - supportive, most pts COMPLETELY recover in 3-6 wks
- post-exposure ppx - HAV vaccine or HAV Ig for close contacts
schistosomiasis
Asia and Africa
fever, urticaria, angioedema, dry cough, eosinophilia
portal vein occlusion can occur due to chronic hepatosplenic schistosomiasis
yeasts in the US
blasto - great lakes, Mississippi
- disseminated disease may occur even in immunocompetent pts - hematogenous spread
- PNA, osteomyelitis, prostatitis, epididymo-orchitis
- skin - wart-like lesions, violaceous nodules, skin ulcers
dx - culture, microscopy, and antigen testing
tx
- mild pulmonary dz - dont have to treat
- mild-mod pulm dz, mild disseminated - oral itraconazole
- severe pulmonary disease, severe disseminated disease, immunocompromised - IV ampho B
coccidioidomycosis - SW and cali
- unilateral infiltrate, ispilateral hilar LAD
- spherules with endospores
histo - midwest, Mississippi, ohio
- asx mild pulmonary infection
Sporotrichosis
rose bushes - pustular ulcerated lesions
- localized to wound and associated lymphatic channels
HSV encephalitis
fever, AMS, seizures, coma
exam
- clinical signs of meningeal irritation are absent in pts with pure encephalitis
- focal neuro deficits (hemiparesis, CN palsies), hyperreflexia
labs/imaging
- CSF studies (increased RBC count), dx by viral DNA on PCR
- MRI - temporal lobe abnormalities
- tx - IV acyclovir
Lyme disease
early localized - erythema migrans (pathognomonic, no need for lab confirmation), myalgais/arthralgias, fatigue, headache
- serology NOT recommended - many will be seronegative
early disseminated
- bells palsy, meningtis, carditis (AV block), migratory arthralgias
- get serology
late - mo-yr
- arthritis, encephalitis, peripheral neuropathy
- get serology
tx - oral doxy (or amox)
diarrhea
B cereus - preformed toxin, rice
S aureus - vomiting (diarrhea is not typical), rapid onset (toxin is preformed)
C diff - abx
C perfringens - unrefrigerated food
Salmonella
Vibrio vulnificus - raw or undercooked shelfish
E coli, Shigella, Campy - BLOODY
- E coli - afebrile, watery –> bloody (if it is the Shiga-toxin producing strain, can look for Shiga toxin in stool), associated with undercooked beef, supportive tx (abx may INcrease the risk of HUS)
- Shigella - bloody diarrhea, fever, and bacteremia
- Campy - blood diarrhea, kids, raw/undercooked meats
rotavirus - gastroenteritis and vomiting
- kids
FQs
levo
cipro - gram neg (and some gram pos, NOT strep)
- GI and GU infections
trichinellosis
undercooked pork in Mexico, China–> gastric acid releases larva that invade SI and develop into worms –> worms release larvae that migrates and forms cysts in striated muscle
intestinal stage (1 week) - abd pain and GI upset
muscle stage (4 weeks) - myositis, fever, subungual splinter hemorrhage, periorbital edema, eosinophilia, elevated CK
Ascariasis
nonproductive cough, eosinophilia
worms can obstruct small bowel or bile ducts
Dengue fever
fever, headache, retro-orbital pain, myalgias
hemorrhagic fever - hemorrhage in skin or nose
typhoid fever
progressive manner: fever –> abd pain, salmon-colored rash –> HSM and abd perf/bleeding
STDs
urethritis in men
- gonorrhea - will see gram neg diplococci on gram stain
- Chlamydia - negative gram stain, culture negative
- tx - azithro or doxy + ceftriaxone for gonorrhea coverage
organ transplant
vaccines for pneumococci and hep B before transplant
inactivated IM flu vax annually (live vaccines are contraindicated after solid-organ transplant)
bactrim to ppx against PCP- can be d/ced in 6-12 mo
osteomyelitis
fever, back pain, focal spinal tenderness
- can also have increased muscle spasm in the area and decreased ROM of back
orgs - S aureus (50% of spinal cases)
dx - blood cultures, ESR/CRP, plain films
- WBC count may be normal (sometimes fever is not present either)
- get MRI if xrays are nl but ESR and CRP are elevated
- CT-guided needle aspiration/bx to confirm dx
note - alarm features for back pain
- fever, recent infection, focal tenderness, hx of cancer
ear infection
malignant (necrotizing) otitis externa - Pseudomonas, affects immunocompromised
- ….granulation tissue, elevated ESR
- consequences - osteomyelitis of skull base or TMJ (pain exacerbated by chewing)
- anti-pseudomonal abx - IV cipro
