ID Flashcards
(42 cards)
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
