infectious diseases for the medicine boards christopher hurt, md division of infectious diseases...
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Infectious Diseases for the Medicine
BoardsChristopher Hurt, MD
Division of Infectious DiseasesJune 2010
2
What is What is suresure to be on the boards to be on the boards
Topic Number of Questions
Epidemiology 5-9
Critical care ID 1-4
CNS infections 1-3
Endocarditis and intravascular infections 0-3
Lower respiratory tract infections 1-5
Enteric infections 1-4
AIDS and HIV infection 2-4
Infectious/septic arthritis 1-2
Procedure- and device-related infections 1-2
Prevention of infectious diseases 2-4
ABIM Exam Blueprint, http://www.abim.org/pdf/blueprint/im_cert.pdf
3
What What may may be on the boardsbe on the boards
Topic Topic
GI complications of HIV Heme/onc complications of HIV
Pulmonary complications of HIV Skin and soft tissue infections
Upper respiratory tract infections Lower respiratory tract infections
STDs and GU tract infections UTIs
Osteomyelitis Bacteremia/sepsis syndromes
Rheumatic fever Nosocomial infections
Immunization Specific causative organisms*
Miscellaneous ID disorders* ID in the elderly
ID in women*whatever the hell that means
ABIM Exam Blueprint, http://www.abim.org/pdf/blueprint/im_cert.pdf
4
What What won’t won’t be on the boardsbe on the boards• Dosages of antimicrobials• Emerging pathogens
» 2009 H1N1 unlikely, but oseltamivir-resistant flu A could be
• Topics that are controversial or which have no consensus guideline, such as…» Treatment of multidrug-resistant TB or HIV
• Probably won’t ask you for second- or third-line antimicrobial selections» (that’s special torture reserved for ID boards)
• Bioterrorism ± » (at least recognize wide mediastinum of inhalation anthrax)
04/18/23 5
Let’s go!Let’s go!
6
Critical care ID - 1Critical care ID - 1
• SIRS = 2 or more of: fever or hypotherm; tachycardia;
tachypnea/hypocarbia; leukocytosis or leukopenia
» NOT necessarily due to an infection
• Sepsis = SIRS plus micro-confirmed or observable infxn
• Severe sepsis = sepsis plus at least one sign of organ
hypoperfusion
» Mottled skin, delayed cap refill, decr UOP, lactatemia, AMS,
abnl EEG, thrombocyto, DIC, ALI/ARDS, cardiac dysfunction
• Septic shock = severe sepsis plus low MAP and/or
pressor requirement
04/18/23 7
Critical care ID - 2Critical care ID - 2
• Drotrecogin alpha (Xigris)
» PROWESS = 96h infusion w/in 24h of presenting
• 28d mortality rate lower with drotrecogin
• Increased bleeding with drotrecogin
» Post-hoc analysis = of greatest benefit to most
severely ill, with APACHE II scores ≥25 or MSOF
» Lower incidence of MSOF among treated patients,
and they also had more rapid recovery of
cardiopulm function
04/18/23 8
Critical care ID - 3Critical care ID - 3
• Who should NOT get drotrecogin alpha (Xigris)
» Preggers or breast-feeding
» Severe thrombocytopenia (<30K)
» ANY invasive procedure within 12h of starting drug
• Spinal epidural anaesthesia is a favorite trivia bit
» Head trauma, intracranial surg, or CVA w/in 3mos
» Known hypercoagulable condition
» Patient not expected to live 28d post-infusion
» Acute pancreatitis with no identified source of infxn
04/18/23 9
Critical care ID - 4Critical care ID - 4
• Lines and bloodstream infections (BSIs)
» Yank all intravascular catheters as soon as feasible
• Dirtiness: femoral > IJ (drool!) > SCL
» If the line is okay, leave the damn thing alone – no
evidence that scheduled (q3-5d) line changes
help reduce nosocomial BSIs
» For site prep, use chlorhexidine gluconate (CHG)
over povidone/iodine (Betadine), if given a choice
04/18/23 10
CNS Infections - 1CNS Infections - 1
• Meningitis = pain, headache, lethargy, function OK
» Aseptic (viral or non-infectious) or bacterial
• Encephalitis = brain abnormalities
» Hemiparesis, AMS, flaccid paralysis, paraesthesias
• Distinctions usu based on CSF – viral dzs have lower
WBC counts, only modest protein elev, near-normal
glucose
» Don’t hang your hat on lymphs vs PMNs to help! You can
see lymphs in early or partially tx’d bacterial meningitis
• Meningoencephalitis = elements of both syndromes
04/18/23 11
CNS Infections - 2CNS Infections - 2
• Encephalitis
» Viral ~ = neuronal involvement by MRI
• Measles, VZV, CMV, influenza, arboviruses
• HSV-1 is responsible for most deaths in encephalitis
• West Nile is like polio or Guillain-Barré – flaccid
ascending paralysis
» Post-infectious aka acute dissem. encephalomyelitis
(ADEM) = neuronal sparing, perivascular inflamm w/
demyelination (often an incidentaloma on MRI)
04/18/23 12
CNS Infections - 3CNS Infections - 3
Meningitis – Viral and Noninfectious
• Viral – enteroviruses, HSV, HIV, WNV, VZV, mumps
» PCR is diagnostic tool, esp for entero and HSV/VZV
» Acute HIV can present with mono-like illness + meningitis
» HSV more likely culprit if pt presenting with 1° genital lesion
• Recurrent HSV-2 associated meningitis episodes = Mollaret’s
• Other bugs = RMSF (Rickettsia), Ehrlichia, Lyme (Borrelia)
• Non-infectious causes
» Malignancy (breast, lung, melanoma, GI, unk primaries)
» Drug-induced (NSAIDs, TMP/SMX, IVIG, OKT3 – immsupp)
04/18/23 13
CNS Infections - 4CNS Infections - 4
Meningitis – Bacterial
• Access CNS either through contiguous spread (e.g.,
parameningeal focus, sinus/middle ear) or hematogenous
• Bugs in adult bacterial meningitis (up to age 60)
» Streptococcus pneumoniae – 60%
» Neisseria meningitidis – 20%
» Haemophilus influenzae – 10%
» Listeria monocytogenes – 6%
» Group B Streptococcus (agalactiae) – 4%
• Over age 60, 70% S.pneumo and 20% Listeria
04/18/23 14
CNS Infections - 5CNS Infections - 5
Meningitis – Bacterial
• Listeriosis has more seizures and focal neuro deficits,
presenting as rhomboencephalitis (ataxia, CN palsies,
nystagmus) – think this in an elderly meningitis vignette
• Gram stain buzzwords
» Gram-positive, lancet-shaped diplococci = S.pneumo
» Gram-negative diplococci = N.meningitidis (meningococcus)
» Gram-negative coccobacilli = H.flu
» Gram-positive rods or coccobacilli = Listeria
04/18/23 15
CNS Infections - 6CNS Infections - 6
Meningitis – Bacterial – TREATMENT
• DO NOT DELAY – if the Q frames pt languishing in ER for
hours before you see him, give abx before doing the LP
• Look for papilledema in lieu of getting a head CT
» If ß-lactam is an option, use it – cidal, penetrates the BBB
» Empirical therapy = hi-dose ceftriaxone + vancomycin
• Ceftriax 2gm q12 = meningococcus & PCN-sensitive S.pneumo
• Vancomycin = PCN-resistant S.pneumo
• IF OVER AGE 50, add ampicillin (±gent) for Listeria
» Only scenario for adjunctive dexamethasone is highly
suspected (or confirmed) pneumococcal meningitis
16
CNS Infections - 7CNS Infections - 7
• Rhinocerebral zygomycosis not “mucormycosis”
» Hyperglycemic diabetic patient in HHS/HONK or DKA
» Acute sinusitis with fever, purulent nasal d/c, HA
» Periorbital or facial swelling ± proptosis
» Invasion of cavernous sinus leads to CN palsies (6&3, 4/5)
» Rhizopus spp. are most common culprits
• Not everyone’s favorite go-to fungus, Aspergillus
» These fungi are vaso-invasive, so on PEx you may see black
mucosal patches – it’s not the mould you’re seeing, it’s
infarcted tissue
» Treatment is with surgery FIRST and adjunctive amphoB
17
Endocarditis - 1Endocarditis - 1• 2007 Modified Duke criteria: 1 major + 1 minor, or 3 minors
Major Minor
Two separate positive blood cxs with typical organism of IE
Viridans group streptococciStreptococcus bovis (COLON CA)
Staphylococcus aureusHACEK
Community-acquired Enterococcus
Vascular phenomena
Arterial emboliSeptic pulmonary infarcts
Mycotic aneurysmsIntracranial hemorrhage
Conjunctival hemorrhagesJaneway lesions
Persistently positive BCxs Fever (>38°C)
Single positive BCx for Coxiella burnetii (Q fever) or phase I IgG titer >1:800
Immunologic phenomena
GlomerulonephritisOsler nodesRoth spots
Rheumatoid factor
Echocardiogram positive for IE
TEE FIRST IF PROSTHETIC VALVES!
Other micro evidence (i.e., unexpected bug)
04/18/23 18
Endocarditis – 2Endocarditis – 2
• Indications for surgical intervention in IE
» Vegetations: persistent after systemic embolization, anterior
mitral leaflet veggies, ≥embolic events in first 2 weeks of
abx, increase in veggie size despite abx
» Valvular dysfunction: acute AI or MR with signs of ventricular
failure, CHF unresponsive to medical tx, valve rupture
» Perivalvular extension: valvular dehiscence/rupture/fistula,
new heart block, large abscess
04/18/23 19
Endocarditis – 3Endocarditis – 3
Native valves
• PCN-susceptible Viridans streptococci and S. bovis MIC≤0.12
» Penicillin G or ceftriaxone, or vanc x 4 wks
» PenG or ceftriaxone PLUS gentamicin x 2 wks (synergy)
1. PCN-intermediate Viridans strep and S. bovis MIC>0.12, ≤0.5
» PenG or ceftriaxone x 4 wks with gent for FIRST 2 wks
» Vanc x 4 wks
• Staphylococcus aureus
1. NafcillinOSSA, oxacillinOSSA, or vancomycinORSA x 6 wks
1. Enterococcus – gentamicin ENTIRE TIME
1. Amp + gent x 4-6 wks, vanc + gent x 4-6 wks
04/18/23 20
Endocarditis – 4Endocarditis – 4
Prosthetic valves
• PCN-susceptible Viridans streptococci and S. bovis MIC≤0.12
1. Penicillin G or ceftriaxone, x 6 wks, ± gent x FIRST 2
2. Vanc x 6 wks
• PCN-int or resistant Viridans strep and S. bovis MIC>0.12
1. PenG or ceftriaxone x 6 wks with gent for all 6 wks
2. Vanc x 6 wks
1. Staphylococcus aureus
» Naf/oxOSSA or vancORSA PLUS rifampin x ≥6 wks, w/gent FIRST 2
2. Enterococcus – gentamicin ENTIRE TIME
1. Amp + gent x 6 wks, vanc + gent x 6 wks
04/18/23 21
Endocarditis – 5Endocarditis – 5
TAKE-HOME MESSAGES FOR ENDOCARDITIS
• Don’t memorize the Duke criteria – it’s intuitive
• Gentamicin shortens the course for “weak” bugs (Low-
PCN MIC Viridans group strep and S.bovis)
• If Enterococcus is present, must use gent entire course
• Prosthetic valve treatment is always 6 wks, sometimes
with adjunctive abx (e.g., rifampin, gent) depending on bug
• Staphylococcus treatment is always 6 wks
04/18/23 22
Intravascular infections – 1Intravascular infections – 1
• Staphylococcus aureus and Salmonella are
associated with vascular (esp aortic) aneurysms
» Think about this dx if high-grade (persistent)
bacteremia in pt without endovascular material
• Syphilis (Treponema pallidum) was once a major
cause of aortitis – late presentation of dz
» Thoracic aortic dilatation with aortic regurgitation
04/18/23 23
Intravascular infections – 2Intravascular infections – 2
• Rocky Mountain spotted fever» Southeastern US (“tick belt” from Arkansas – NC – FL)
» Rickettsia ricketsii attach to vascular endothelium = leak
» Fever, severe HA, rash in 90% (beware pts of color!),
myalgias, focal neuro signs, thrombocyto, ARF, hypoNa
» Doxycycline ASAP – treat empirically; no good acute dx tool
04/18/23 24
Lower respiratory tract infections - 1Lower respiratory tract infections - 1
Community-Acquired Pneumonia
• Bugs: Strep pneumo, Mycoplasma pneumoniae, H.flu,
Chlamhydophila pneumoniae, respiratory viruses, Legionella
• Outpatient tx
» Previously healthy, no abx w/in 3 mos? Macrolide or doxy
» Comorbidities? Respiratory FQ OR [ß-lactam + macrolide]
• Inpatient, non-ICU – resp FQ OR [ß-lactam + macrolide]
• Inpatient, ICU – ß-lactam PLUS [resp FQ or azithro]
» ß-lactam choices: cefotaxime, ceftriaxone, amp/sulbactam
» Pseudomonas? pip/tazo, cefepime, imi/mero ± aminoglycoside
» MRSA/ORSA? ADD vancomycin or linezolid
25
Lower respiratory tract infections - 2Lower respiratory tract infections - 2
Healthcare and Ventilator-Acquired Pneumonias
• Bugs: Pseudomonas, E.coli, Klebsiella, Acinetobacter, S.aureus
• Increased risk for multidrug resistant (MDR) bugs?
» Abx w/in 90d, current hospitalization ≥5d, high-freq of abx resistance
in unit, risk factor for HCAP (hospitalization x2d in prior 90d, nursing
home resident, home infusion, dialysis, close contact)
• HAP/VAP if no known risk factors for MDR-bug (realistically, very rare)
» Ceftriaxone or levoflox/moxi or amp/sulbactam or ertapenem
• High risk for MDR-organisms or presenting with late-onset dz
» Antipseudomonal ß-lactam: cefepime, ceftaz, imi, mero, or pip/tazo
AND cipro, levo, amikacin, gent, or tobra
» If MRSA concern, ADD linezolid or vancomycin NOT daptomycin
26
Lower respiratory tract infections - 3Lower respiratory tract infections - 3
• BMT and SOT recipients
• Nocardia spp. – if in lung, think of brain, too!» Beaded, branching, filamentous bacteria, ± acid-fast
» Incidence has dropped due to TMP/SMX prophy use post-xp
» TMP/SMX or imipenem empirical tx, awaiting susceptibilities
» Get a CT of the head looking for ring-enhancing lesions
• Aspergillus spp.» Marijuana smoking post-xp is a risk factor
» “Crescent sign” on chest CT is buzzword
» Vasoinvasive and tissue destructive
» AmphoB, echinocandin (caspo/mica/anidula), or vori/posa
04/18/23 27
Lower respiratory tract infections - 4Lower respiratory tract infections - 4
• Pneumocystis jiroveci (still called PCP)
» CD4 ≤ 200-250
• HIV and transplant pts +
fludarabine (CD4-penic)
» Nonproductive cough,
fever, insidious SOB
» Steroids if PaO2 <70
» Tx = IV TMP/SMX or
IV pentamidine* *Inhaled only for prophy
28
Lower respiratory tract infections - 5Lower respiratory tract infections - 5
• Mycobacterium tuberculosis
» TST/PPD is a crappy test, but don’t use “anergy” panel
» KNOW THE THRESHOLDS FOR POSITIVE TST/PPD!!!
5 mm 10 mm
HIV-infected Recent immigrant from TB endemic country
Recent contact to case with active TB IDUs
Abnormal CXR c/w prior pulmonary TBResident/employee of high-risk congregate
setting (jail, shelter, nursing home)
Organ transplant recipients Mycobacteriology lab personnel
Other immune compromised (steroids, TNF-a antagonists)
Children < 4 yo
Young people exposed to high-risk adults
15 mm is for everyone else (i.e., no known TB risk factors)
29
Lower respiratory tract infections - 6Lower respiratory tract infections - 6
• Mycobacterium tuberculosis
» Treatment always initiated with four drug “RIPE” regimen, at
weight-based dosing
• Isoniazid – hepatotoxicity, anion gap acidosis (I in MUDPILES)
• Rifampin – inducer of metabolism of other drugs, orange body
fluids, hepatotoxicity
• Ethambutol – optic neuritis (color blindness)
• Pyrazinamide – hepatotoxicity, nausea-inducing
» Pulmonary TB: total of 6 months treatment ALL ON DOT
• First 8 weeks on RIPE – if fully susceptible and smear negative
at 2 month recheck, then OK to narrow to just INH + Rifampin
04/18/23 30
Lower respiratory tract infections - 7Lower respiratory tract infections - 7
• Histoplasma, Coccidioides, Cryptococcus
» All gain entry through inhalation, then disseminate
» Histoplasma – Mississippi-Ohio River Valley, interstitial
pneumonia, mucocutaneous ulcers, splenomegaly, marrow
suppression, fibrosing mediastinitis, “coin” lesion in HIV–
» Coccidioides – Desert SW (Mexican immigrants and eco-
tourists), hilar adenopathy, arthralgias, erythema nodosum
(can be mistaken for sarcoidosis)
» Cryptococcus – pneumonitis is usually subclinical, may have
cryptococcomas of lung, can be normal hosts but if
compromised (HIV, steroids, transplant) need LP
04/18/23 31
Enteric infections - 1Enteric infections - 1
• Norovirus
» Rapid-onset explosive outbreak with quick resolution
• Child exposures, cruise ships, congregate living facilities
» Low infectious inoculum, highly transmissible
» Vomiting precedes abd cramping, fever (<50%), watery
diarrhea, constitutional sxs (HA, chills, myalgias) x 2-3d
» Can cause deaths among the elderly
» Treatment = oral rehydration, supportive care
• Antimotility and antisecretory drugs are okay to use
32
Enteric infections - 2Enteric infections - 2
• Dysentery = bloody stools; 4 main causes in US…
» Shiga toxin-producing E.coli (60% are O157:H7)
• Watery diarrhea becomes bloody in 1-5d; abd cramps, no fever
• Causes hemolytic-uremic syndrome if toxin reaches kidneys
» Shigella (outbreaks uncommon; more in developing world)
» Campylobacter – poultry, unpasteurized milk; Guillain-Barré
» Non-typhoid Salmonella – poultry, pet reptiles and turtles
• Treatments
» Shiga toxin-producing E.coli – Abx not recommended
» Shigellosis, salmonellosis – ciproflox, levoflox, azithro
» Campylobacter jejuni – azithro
04/18/23 33
Enteric infections - 3Enteric infections - 3
• Clostridium difficile diarrhea
» Toxin assay for diagnosis, but don’t attempt test-of-cure
» Initial episode, mild-to-moderate
• Metronidazole 500mg PO (not IV) q8h x10-14d
» Initial episode, severe (WBC ≥15, Cr ≥1.5x premorbid level)
• Vancomycin 125mg PO (not IV) q6h x 10-14d
» Initial episode, severe and complicated by shock, megacolon
• Vancomycin 500mg PO or pNGT PLUS metronidazole 500 q8
• If complete ileus, consideration for intrarectal vancomycin
» First recurrence = same as initial episode
» Second recurrence = vancomycin taper
04/18/23 34
HIV and AIDS - 1HIV and AIDS - 1
• HIV-1 predominates
» HIV-2 limited to W. Africa
• ssRNA retrovirus
• AIDS is defined by:
» CD4 < 200 cells/µL
» CD4% < 14%
» Presence of AIDS-defining
illness at any CD4
04/18/23 35
HIV and AIDS - 2HIV and AIDS - 2
• ELISA = highly sensitive
» Better to have FP than miss a TP!
• Western blot = highly specific
» Indeterminate Western blots are
rare… but can be caused by:
• Neoplasms, dialysis, thyroid dz,
bilirubinemia, SLE, pregnancy,
immunizations (tetanus, HIV)
nephrotic-range proteinuria
36
HIV and AIDS - 3HIV and AIDS - 3
• Acute retroviral syndrome is
a mononucleosis-like illness
» Fever
» Maculopapular rashThink syphilis, too!
» Mucocutaneous ulcers
» Pharyngitis ± tonsillar
enlargement
» Lymphadenopathy
» Meningitis (infrequent)
• DIAGNOSIS OF ACUTE HIV IS BY RNA, NOT Ab!!!
37
HIV and AIDS - 4HIV and AIDS - 4
Initial mgm’t – Prophylaxis
• CD4 > 200, no prophylaxis necessary
• CD4 < 200
» Pneumocystis jiroveci and Toxoplasmosis
• TMP/SMX > dapsone > atovaquone
• Aerosolized pentamidine prevents ONLY Pneumocystis
» Do NOT need fluconazole for thrush “prophylaxis”
• CD4 < 50
» Mycobacterium avium complex (“MAI” doesn’t exist!)
• Azithromycin 1200mg once weekly
38
HIV and AIDS - 5HIV and AIDS - 5
Initial mgm’t – Antiretrovirals
• For CD4 < 200 or if AIDS-defining illness, everyone
should get on ARVs
» Recent (2009, so NOT on boards yet) evidence suggests
starting ARVs during some acute OIs reduces mortality
» For now, ABIM would say to start after stabilization, etc.
• Btw 200-350, recommended to start
• Over 350, decision btw pt and provider
39
HIV and AIDS - 6HIV and AIDS - 6
Initial mgm’t – Antiretrovirals
• Current testable recommendations are probably slightly
out-of-date (circa 2008); field moving rapidly
Dual NRTI (any one row) Companion (any one row)
+EfavirenzNNRTI
Truvada® (tenofovir/emtricitabine) Atazanavir + ritonavirPI
Epzicom® (abacavir/lamivudine) Fosamprenavir + ritonavirPI
Lopinavir/ritonavirPI
Alternatives
Combivir® (zidovudine/lamivudine)
didanosine + lamivudine
+NevirapineNNRTI
Atazanavir (“unboosted”) PI
Fosamprenavir (“unboosted”) PI
04/18/23 40
HIV and AIDS - 7HIV and AIDS - 7
• Cryptococcal meningitis
» Malaise, headache, N/V, low-grade fevers, without much
meningismus or AMS
» Think of dx also in ALL, Hodgkin’s, or recent steroid use
» Get serum crypto Ag – India ink is rarely used
» Morbidity/mortality comes from increased ICP, so
get opening pressure on LP and perform serial LPs
• Can also place lumbar drain or ventricular drain, if needed
» Amphotericin B + flucytosine x14d for CNS disease
• THEN switch to oral fluconazole and stay on it until CD4 > 200
41
HIV and AIDS - 8HIV and AIDS - 8
Antiretroviral side effects
• ddI, d4T/stavudine, AZT/zidovudineNRTIs - lactic acidosis
• TenofovirNRTI - Fanconi-like syndrome w/“creatinine creep”
• AbacavirNRTI – hypersensitivity rxn (if HLA B*5701 present)
• EfavirenzNNRTI - teratogenic, causes vivid dreams
• NevirapineNNRTI - hepatotoxic if started with high CD4s,
SO AVOID USING NEVIRAPINE IN PEP REGIMENS
• IndinavirPI - nephrolithiasis
• RitonavirPI - “booster” agent, tons of drug-drug interactions
• AtazanavirPI - Gilbert-like syndrome of hyperbili ± jaundice
42
Antimicrobial adverse effectsAntimicrobial adverse effects• Sulfa drugs – rash, AIN/ARF, kernicterus in neonates
• TMP – hyperkalemia (decr renal tubular excretion)
• ß-lactams – marrow, seizures, AIN/ARF
• Daptomycin – rhabdomyolysis
• Metronidazole – disulfiram-like reaction with EtOH
• Oxacillin – hepatitis/transaminitis
• Pentamidine – pancreatitis, hypoglycemia
• Amphotericin – renal failure, rigors (meperidine)
• Vancomycin – “red man” (histamine release), nephro/ototox (??)
• Aminoglycosides –ototoxicity, c/i in myasthenia gravis
• Linezolid – marrow toxicity, MAOI activity (serotonin syndrome)
04/18/23 43
Infectious/septic arthritis - 1Infectious/septic arthritis - 1
• Diagnosis
» Arthrocentesis to eval for crystalline arthropathy
» Generally >50K cells/µL as threshold for septic joint
» Look for Gram-positives… #1 cause is S.aureus,
followed by streptococci
Monoarticular joint presentations
• Late Lyme arthritis (Borrelia burgdorferi)
» Knee > shoulder > ankle > elbow >
TMJ > wrist > hip
» Effusion is greater than the pain
» Fluid can meet WBC criteria for septic joint, but uncommon
» Diagnosis relies on serologies
• Gonorrhea
» Triad of migratory polyarthralgia, dermatologic lesions
(macules, papules/pustules), tenosynovitis
» Dx is by confirming genital or extragenital GC infection44
Infectious/septic arthritis - 2Infectious/septic arthritis - 2
45
STIs and GU tract infections - 1STIs and GU tract infections - 1
• Gonorrhea (Neisseria gonorrhoeae)
» Gram-negative intracellular diplococcus
» Purulent urethritis or cervicitis
» Most cases resolve spontaneously – treat to prevent
disseminated gonococcal infection (DGI)
• Fevers, asymmetric mono/oligoarticular arthritis (knee, ankle) or
• Tenosynovitis - muscle pain; overlying papules w/hemorrhage
» Uncomplicated GU dz = IM ceftriaxone or PO cefixime, x1
» Extragenital dz or DGI = IM ceftriaxone, x1
» ALWAYS co-treat for Chlamydia with 1gm azithro, x1
» NEVER use a quinolone for an STI on the boards!
46
STIs and GU tract infections - 2STIs and GU tract infections - 2
• Chlamydia trachomatis (and the catch-all, NGU)
» Includes Ureaplasma urealyticum, Mycoplasma genitalium
» Incubation period is longer for CT (1-4wks) than GC (2-6d)
» Clear (non-purulent) discharge; Gm stain = WBC, no bugs
» Treat with 1gm azithromycin PO, x1 or doxy 100 q12 x7d
• Pelvic inflammatory disease
» Can be from GC or CT, sometimes vaginal anaerobes
» Fitz-Hugh-Curtis = purulent perihepatitis with mild LFT chgs
» If pregnant, must admit the patient
» Tx w/ceftriaxone x1, doxy and metronidazole x14d
04/18/23
STIs and GU tract infections - 3STIs and GU tract infections - 3
• Syphilis – RPRnon-treponemal, confirmtreponemal = MHA-TP, TP-PA
» 1° = painless chancre, ~21d after contact, lasting ~3-6 wks
» 2° = non-pruritic skin rash and mucous membrane lesions
• Rough, red or brownish spots on trunk, palms and soles
• Systemic symptoms with fever, LAD, sore throat, hair loss
• Syphilitic hepatitis (1° & 2°) = cholestatic, but alk phos >> bili
» Latent – seroreactivity without e/o disease
• Early latent – if acquired syphilis within the prior year
• Late latent – unknown acquisition date
» 3°/Late – evidence of end-organ damage – PCN x 3 wks
» Neurosyphilis – IV PCN x14d, desensitize in ICU if needed
PCN x1
PCN x1
PCN x1
PCN x3 wks
04/18/23 48
STIs and GU tract infections - 4STIs and GU tract infections - 4
• Herpes
» Painful ulcerations of genital mucosa, usually from HSV-2
» Remember primary genital lesion assoc w/ HSV meningitis
» First episode: ACV, famciclovir, or vACV x 7-10d
» Suppressive therapy does reduce viral shedding and
prevent recurrent episodes
• ACV 400 q12, famciclovir 250 q12, or vACV 500 q24
04/18/23 49
STIs and GU tract infections - 5STIs and GU tract infections - 5
Clue cells Normal
• Trichomoniasis
» If it’s moving fast on a wet prep, it’s Trichomonas vaginalis
» Frothy, thin, foul-smelling d/c for women; men often w/o sxs
» Kill it with metronidazole 2gm po, x1 unless pregnant, then
use metronidazole 500 q12h x7d. AVOID EtOH (disulfiram)
• Bacterial vaginosis – NOT an STI
» “Salt-and-pepper”
covered clue cell
» Fishy odor, pH > 5.0
» Metro 500 q12h x7d
04/18/23 50
Hepatic infections - 1Hepatic infections - 1
• Hepatitis B
» dsDNA virus
» Blood and body fluids
are source
» Majority (95%) of
normal hosts
will clear virus
» Strong assoc w/HCC,
esp among Asians who
were vertically infected
04/18/23 51
Diagnosis1
sAg
2
eAg
3
cAb
4
eAb
5
sAb
Acute hepatitis + + IgM – –
Window period* – +/ – IgM +/ – –
Recovery – – IgG +/ – +
Immunized – – – – +
Chronic replicative + + IgG – –
Chronic non-replicative + – IgG + –
*Order after acute infection: sAg+ sAg–,(anti)HBcIgM+ sAb+. Because sAg drops before sAb detectable,
only way to confirm HBV at that point is cIgM
04/18/23 52
Prevention of infectious diseases - 1Prevention of infectious diseases - 1
• Endocarditis prophylaxis
» 2007 ACC / IDSA guidelines changed this radically
» Cardiac abnormalities for which prophylaxis is reasonable
• Prosthetic valve or prosthetic material used for valve repair
• Prior history of infective endocarditis
• Congenital heart disease – repaired or unrepaired
• Cardiac transplant recipients with valvulopathy
» Dental – any manipulation of gingival tissue or periapical
region of teeth, or perforation of oral mucosa
• Amoxicillin 2gm 30-60 minutes before procedure
» GI and GU tract procedures don’t get prophylaxed for IE
04/18/23 53
Prevention of infectious diseases - 2Prevention of infectious diseases - 2
• Malaria prophylaxis
» Big question is, can chloroquine (CQ) be used or not?
• Sensitive = Mexico Costa Rica; Argentina; Turkey Iraq
• Resistant = All of Africa; all of Asia; Panama Argentina
» If CQ sensitive: Chloroquine or hydroxychloroquine
• Start 1-2 wks before travel, take once weekly and x4 wks after
» If CQ resistant (in general order of preference):
• Atovaquone/proguanil: 1-2d before travel, daily, x7d after home
• Doxycycline: 1-2d before travel, daily, x4 wks after home
• Mefloquine: 2 wks before travel, weekly, x4 wks after home
» Psychotic episodes, szs, mental status changes with mefloquine
04/18/23 54
Prevention of infectious diseases - 3Prevention of infectious diseases - 3
• Immunizations
» NEVER give live virus vaccine to pregnant women or
HIV-infected patients with CD4 < 200
• Live attenuated influenza, varicella, zoster, MMR,
yellow fever (can be given in pregnancy if @ risk)
» Tetanus toxoid (as Td) and inactivated influenza are
okay in pregnancy, preferably after 1st trimester
» HAV & HBV, pneumococcal & meningococcal
conjugate vaccines are prob safe in pregnancy;
no data
04/18/23 55
Prevention of infectious diseases - 4Prevention of infectious diseases - 4
• Hospital precautions
» Airborne – varicella (incl zoster/shingles), TB, measles
» Droplet – H.flu, meningococcus, diphtheria, pertussis,
Strep pharyngitis, adenovirus, influenza, RSV
» Contact – C.diff, norovirus, RSV, pediculosis (crabs),
scabies, ORSA/MRSA, VZV
» Shingles can come off airborne & contact once dry, crusted
• Handwashing is required for C.difficile infections –
alcohol-based sanitizers don’t kill the spores
Prevention of infectious diseases - 5Prevention of infectious diseases - 5
• Influenza remember drift = year-to-year; shift = pandemics
» Moving target; unlikely pandemic H1N1 will appear on ABIM
» Prophylaxing close contacts is appropriate; use OST or ZNV
based on what the question stem tells you about strain
Influenza strain Oseltamivir (OST) Zanamivir (ZNV) Adamantanes
A / H3N2(Seasonal) S S R
A / H1N1(Seasonal) R S S
A / 2009 H1N1(Pandemic) S* S R
B S S R
* Sporadic resistance to oseltamivir was reported during the 2009 H1N1 pandemic; all isolates remained sensitive to zanamivir
04/18/23 57
Prevention of infectious diseases - 6Prevention of infectious diseases - 6
• Meningococcus
» Vaccine covers serogroups A, C, Y, W-135 – but misses B,
the major cause in the US (not included in any vaccine)
» Everyone in the pt’s room will want treatment/prophylaxis
(and we often prophylax many more than need it)
» For the boards, it’s close contacts to respiratory droplets
• Anyone with prolonged exposure (8h or more) w/in 3 feet
» Dorm roommate, but not classmates or other casual contacts
• Anyone directly exposed to oral secretions w/in 1 wk of dx
» Boyfriend/girlfriend, anyone doing CPR or intubating pt
» Rifampin 600 q12 x2d, ciproflox 500 x1, ceftriax 250 x1
58
Prevention of infectious diseases - 7Prevention of infectious diseases - 7
• Prevention of VAP
» Use orotracheal intubation, vs nasotracheal/assisted
» Avoid NGTs – use OGTs
» Continuous aspiration of subglottic secretions, if available
» Maintain adequate ETT cuff pressure, to occlude trachea and
prevent leakage into the lower respiratory tract
» Extubate as early as possible (minimize vent time)
» Keep patient in semirecumbent position (30-45°),
esp when receiving an enteral feeding
» Oral decontamination with chlorhexidine gluconate (± data)
» Avoid sedation regimens that depress cough reflexes
04/18/23 59
Prevention of infectious diseases - 8Prevention of infectious diseases - 8
• HIV PEP
» Two different guidelines exist: occupational and non
» Start ARVs within 72h, ideally within first 20 mins
» Risk increases with the gauge of the needle
• Hollow-bore needle > scalpel > suture needle
» Data support using dual NRTI therapy by itself, but
recommendation is to give the patient HAART
• Combivir (zidovudine/lamivudine) or Truvada
(tenofovir/emtricitabine) PLUS Kaletra (lopinavir/ritonavir) or
efavirenz
• AVOID NEVIRAPINE DUE TO RISK OF HEPATOTOXICITY AT
HIGH CD4 COUNTS
04/18/23 60
Lightning round!Lightning round!
04/18/23 61
Streptococcus pneumoniae, an encapsulated (“halos”) Gram+ diplococcusStrep = pairs and chains Staph = clusters
04/18/23 62
Ramsay-Hunt syndrome = facial nerve paralysis, ear pain, and loss of taste sensation in anterior 2/3 of tongue,
from VZV reactivation in geniculate ganglion
Shingles from varicella-zoster virus
in a young male patient receiving chemotherapy
04/18/23 63
Proper technique for measuring TST/PPD (left)Scar from Bacille-Calmette Guerin (BCG) vaccine (right)
04/18/23 64
Purpuric skin lesions of disseminated meningococcemia
Waterhouse-Friderichsen syndrome is adrenal hemorrhage from N.meningitidis
65
Disseminated primary varicella in adults shows multiple stages of healing,sometimes pustular (left image) – smallpox has all lesions at same stage
04/18/23 66
Multiply parasitized RBCs with characteristic “headphone” form (arrow) of Plasmodium falciparum malaria
04/18/23 67
Nodular, hyperpigmented, sometimes violaceous lesions of Kaposi sarcoma,caused by human herpesvirus 8 (aka KS-HV)
04/18/23 68
Painless genital ulcer (chancre) of primary syphilis
04/18/23 69
Slightly umbilicated papules of molluscum contagiosum(a poxvirus) in an HIV-infected patient.
04/18/23 70
Cellulitis from Streptococcus pyogenes. Using adjunctive clindamycinfor the first 72h is reasonable, to shut of toxin production – if concern for TSS.
04/18/23 71
Plaques of thrush from Candida albicans in an HIV-infected patient.
04/18/23 72
Thin, frothy cervical discharge from Trichomonas vaginalis.
04/18/23 73
Lymphangitic spread of Sporothrix schenckii, a thermal dimorphic mould. Rose gardening is the buzzword.
If fresh or brackish water exposure, think Mycobacterium marinum.
04/18/23 74
Tinea versicolor from Malassezia furfur. Can also cause sepsis incritically ill patients receiving TPN.
04/18/23 75
Widened mediastinum from Bacillus anthracis inhalation. Ciprofloxacin.
04/18/23 76
Ring-enhancing lesions of cerebral toxoplasmosis in an AIDS patient.No reliable way to radiographically distinguish toxo from CNS lymphoma.
04/18/23 77
Pruritic skin lesions in webspaces, from the scabes mite (Sarcoptes scabei).
04/18/23 78
Vaginal candidiasis. Single dose of fluconazole 150 or 200.
04/18/23 79
Cryptococcus neoformans on India ink prep. Halos are the organism’s polysaccharide capsule.
04/18/23 80
Measles exanthem – but could also be a morbilliform (measles-like) drug eruption.
04/18/23 81
Epidemiology - 1Epidemiology - 1
Disease status
Test result + –
+ TP FP T+
– FN TN T–
D+ D– N
Sensitivity: probability of positive test in those with diseaseTP / (TP+FN) = TP / D+
Specificity: probability of negative test in those without disease TN / (TN+FP) = TN / D–
04/18/23 82
Epidemiology - 2Epidemiology - 2
Disease status
Test result + –
+ TP FP T+
– FN TN T–
D+ D– N
PPV: probability of having disease in those who test positiveTP / (TP+FP) = TP / T+
NPV: probability of not having disease in those who test negativeTN / (TN+FN) = TN / T–
04/18/23 83
Prevalence: what proportion has the disease right now?_____________# cases____________
all those with dz PLUS at risk for dz
04/18/23 84
Incidence: what proportion develop the disease over time?__________# new cases__________all those with dz PLUS at risk for dz
over time t
04/18/23 85
Epidemiology - 5Epidemiology - 5
PPV and NPV depend onprevalence•Tests perform better when used in a higher prevalence group•This is why we don’t test for influenza (usually) in the “off-season”
0% --------------------> 2%
Figure from Bill Miller