Infectious Diseases for the Medicine Boards Christopher Hurt, MD Division of Infectious Diseases...

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


• 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


• 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


• 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


• 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


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


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


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


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

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• 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

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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


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


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


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

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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

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• 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


• 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

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• 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)

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• 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


• 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

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• 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


• 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


• 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


• 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!!!

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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


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


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


• 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


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


• 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


• 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


• 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


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


• 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

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• 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

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• 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


• 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

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• 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

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• 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

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• 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

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Lightning round!Lightning round!

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Streptococcus pneumoniae, an encapsulated (“halos”) Gram+ diplococcusStrep = pairs and chains Staph = clusters

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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

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Proper technique for measuring TST/PPD (left)Scar from Bacille-Calmette Guerin (BCG) vaccine (right)

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Purpuric skin lesions of disseminated meningococcemia

Waterhouse-Friderichsen syndrome is adrenal hemorrhage from N.meningitidis

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Disseminated primary varicella in adults shows multiple stages of healing,sometimes pustular (left image) – smallpox has all lesions at same stage

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Multiply parasitized RBCs with characteristic “headphone” form (arrow) of Plasmodium falciparum malaria

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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

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Slightly umbilicated papules of molluscum contagiosum(a poxvirus) in an HIV-infected patient.

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Cellulitis from Streptococcus pyogenes. Using adjunctive clindamycinfor the first 72h is reasonable, to shut of toxin production – if concern for TSS.

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Plaques of thrush from Candida albicans in an HIV-infected patient.

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Thin, frothy cervical discharge from Trichomonas vaginalis.

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Lymphangitic spread of Sporothrix schenckii, a thermal dimorphic mould. Rose gardening is the buzzword.

If fresh or brackish water exposure, think Mycobacterium marinum.

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Tinea versicolor from Malassezia furfur. Can also cause sepsis incritically ill patients receiving TPN.

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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.

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Pruritic skin lesions in webspaces, from the scabes mite (Sarcoptes scabei).

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Vaginal candidiasis. Single dose of fluconazole 150 or 200.

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Cryptococcus neoformans on India ink prep. Halos are the organism’s polysaccharide capsule.

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Measles exanthem – but could also be a morbilliform (measles-like) drug eruption.

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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–

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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–

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Prevalence: what proportion has the disease right now?_____________# cases____________

all those with dz PLUS at risk for dz

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Incidence: what proportion develop the disease over time?__________# new cases__________all those with dz PLUS at risk for dz

over time t

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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

Infectious Diseases for the Medicine Boards Christopher Hurt, MD Division of Infectious Diseases...

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Transcript of Infectious Diseases for the Medicine Boards Christopher Hurt, MD Division of Infectious Diseases...