KJZ First Aid For The USMLE Step 2 CK: Infectious Disease – Flashcards
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Classic symptoms of pneumonia
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Sudden onset, fever, productive cough (purulent yellow-green sputum or hemoptysis), dyspnea, night sweats, pleuritic
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Atypical symptoms of pneumonia
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Gradual onset, dry cough, headaches, myalgias, sore throat
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Pts who may have minimal or atypical signs of pneumonia on PE
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Elderly, COPD, diabetes, immunocompromised
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PE of pneumonia
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? or bronchial breath sounds, rales wheezing, dullness to percussion, egophony, tactile fremitus
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Common causes of pneumonia: children (6 wks - 18 yrs)
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Viruses (RSV), Mycoplasma, Chlamydia pneumoniae, Streptococcus pneumoniae
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Common causes of pneumonia: adults (18 - 40 yrs)
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Mycoplasma, C. pneumoniae, S. pneumoniae
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Common causes of pneumonia: Adults (40 - 65 yrs)
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S. pneumoniae, H. influenzae, Anaerobes, Viruses, Mycoplasma
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Common causes of pneumonia: Elderly (66+)
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S. pneumoniae, Viruses, Anaerobes, H. influenze, Gram + rods
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Atypical causes of pneumonia
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Mycoplama, Legionella, Chlamydia
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Nosocomial (hospital acquired) causes of pneumonia
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Gram - rods (GNRs), Staphlococcus, anaerobes
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Causes of pneumonia in Immunocompromised
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Staphylococcus, Gram + rods, Fungi, Viruses, Pneumocystis jiroveci (w/ HIV), Mycobacteria
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Causes of aspiration pneumonia
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Anaerobes
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Causes of pneumonia in Alcoholics/IV drug users
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S. pneumonia, Klebsiella, Staphylococcus
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Causes of pneumonia in Cystic Fibrosis (CF)
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Pseudomonas, Burkholderia, S. aureus, Mycobacteria
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Causes of pneumonia in COPD
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H. influenzae, Moraxella catarrhalis, S. pneumoniae
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Causes of Postviral pneumonia
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Staphlyoccocus, H. influenzae
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Causes of pneumonia in Neonate
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Group B Streptococci (GBS), E. coli
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Causes of recurrent pneumonia
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Obstruction, Bronchogenic carcinoma, Lymphoma, Wegener's granulomatosis, immunodeficiency, unusual organisms (e.g. Nocardia, Coxiella burnetii, Aspergillus, Pseudomonas)
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Workup for pneumonia
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Physical exam, CXR, CBC, sputum Gram stain ; cx, nasopharygeal aspirate, blood cx, ABG
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Test for Legionella pneumonia
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Urine Legionlla antigen test (detects only serogroup 1), sputum staining w/ direct fluorescent antibody (DFA), Cx
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Test for Chlamydia pneumoniae
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Serologic testing, Cx, PCR
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Test for Mycoplasma pneumonia
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Usu clinical, Serum cold agglutinins ; serum Mycoplasma antigen may also be sued
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Test for Streptococcus pneumonia
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Urine pneumococcal antigen test, Culture
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Test for Viral pneumonia
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Nasopharyngeal aspirate, Rapid tests for pathogens (influenza, RSV), DFA, Viral culture
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What makes an adequate sputum Gram stain
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Many PMNs (;25 cells/hpf), few epithelial cells (;25 cells/hpf)
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Criteria that risk stratifies pts with pneumonia
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PORT criteria (pneumonia severity index), based on age, comorbidity, ; presentation (Do not apply to AIDS pts)
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When is in-hospital tx w/ IV antibiotics recommended for pts?
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;65 yrs of age, Comorbitidities (alcoholism, COPD, DM, malnutrition), Immunosuppression, Unstable vitals or signs of respiratory failure, AMS, and/or multilobar involvement
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Coverage to add for pts with obstructive dz (CF or bronchictasis)
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Pseudomonal, Staphylococcal, anaerobic coverage
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Likely pathogens ; tx for pt w/ OP community-acquired pneumonia, ?65 yo, otherwise healthy
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Suspected Pathogens: S. pneuoniae, Mycoplama pneumonia, C. pneumoniae, H. influenze, viral Empiric coverage: Macrolide (azithromycin), doxycycline, or fluoroquinolone
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Likely pathogens ; tx for pt ;65 yo or w/ comorbidity (COPD, heart failure, renal failure, DM, liver dz, EtOH abuse)
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Suspected Pathogens: S. pneumoniae, H. influenzae, aerobic GNRs (E. coli, Enterobacter, Klebsiella), S. aureus, Legionella, viruses Empiric coverage: Macrolide or fluoroquinolone; consider adding a second-generation cephalosporin or ?-lactam to the macrolide.
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Likely pathogens ; tx for pt w/ Community-acquired pneumonia requiring hospitalization
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Suspected Pathogens: S. pneumoniae, H. influenzae, anaerobes, aerobic GNRs, Legionella, Chlamydia Empiric coverage: Extended spectrum cepalosporin, ?-lactam/?-lacatamase inhibitor, or fluoroquinoloe; add a macrolide if atypical organisms are suspected
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Likely pathogens ; tx for pt w/ Community-acquired pneumonia requiring ICU care
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Suspected Pathogens: S. pneumoniae, H. influenzae, anaerobes, aerobic GNRs, Mycoplasma, Legionella, Pseudomonas Empiric coverage: Fluoroquinolone or extended-spectrum cephalosporin or ?-lacatam/?-lactamase inhibitor + macrolide
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Likely pathogens ; tx for pt w/ Institution-/hospital-acquired pneumonia (pts hospitalized ;48 hrs or in a long-term care facility ;14 days)
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Suspected Pathogens: GNRs (including Pseudomonas ; Acinetobacter), S. aureus, Legionella, mixed flora Empiric coverage: Extended-spectrum cephalosporin or ?-lactam w/ antipseudomonal activity or carbapenem. Consider adding an aminoglycoside or a fluoroquinolone for coverage of resistant organisms (Pseudomonas) until lab sensitivites identify the best single agent.
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Likely pathogens ; tx for pt who is critically ill or worsening over 24-48 hrs on initial antibiotic therapy
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Suspected Pathogens: MRSA Empiric coverage: Add vancomycin or linezolid; borader gram- coverage
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Cause of tuberculosis
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Mycobacterium tuberculosis
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Organ systems infected by TB
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Pulmonary most common, Can infect almost any including lungs, CNS, GU tract, bone, and GI tract
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Risk factors for active TB (reactivation)
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Immunosuppresion (HIV), Alcoholism, Preexisting lung dz, diabetes, Advancing ages
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Risk factors for TB exposure
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Homelessness, Crowded living conditions (prison), Immigration/travel from developing nations, Working in an allied health profession, Interacting with known TB contacts
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History/PE of pt w/ TB
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Cough, Hemoptysis, dyspnea, Weight loss, Fatigue, Night sweats, Fever (TB = common cause of fever of unknown origin), Cachexia, Hypoxia, Tachycardia, Lymphadenopathy, Abnormal lung exam, Prolonged (;3 wk) sx duration
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Type of pt who presents with atypical signs/sx ; has higher rates of extrapulmonary TB
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HIV
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Tests to diagnose active TB
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1. Mycobacterial culture of sputum = gold standard, takes weeks 2. Acid-fast stain = rapid, but lacks sensitivity
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CXR findings in TB
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Cavitary infiltrate in upper lobe, HIV pts or those with 1° TB may show lower lobe infiltrates w/ or w/o cavitation, Multiple fine nodular densities distributed throughout both lungs = miliary TB
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Miliary TB
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Hematologic or lymphatic dissemination of TB
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What to do if AFB stain is - but there is a high degree of clinical suspicion
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Bronchoscopy w/ bronchoalveolar lavage or bx (HIV pts have high rate of - sputum stains = -AFB smear accompanied by a + cx)
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Drugs for TB
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"RIPE" Rifampin, INH, Pyrazinamide, Ethambutol
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Test to diagnose Latent TB infection (LTBI, AKA previous exposure)
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+ PPD test, But immunocompromised individuals w/ LTBI may not mount a +LTBI (anergy) = interferon-? release assay, All cases of LTBI should be evaluated with CXR to r/o active dz
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Tx of Active TB
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All cases should be reported to local ; state health departments, Respiratory isolation should be instituted, Tx with 4 drug regimen (rifampin, INH, pyrazinamide, ethambutol) x 2 mos, followed by rifampin ; INH x 4 mos,
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SE of INH
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Peripheral neuritis (Administer vit B6 (pyridoxine)), Hepatitis
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Tx of LTBI
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+ PPD but no s/s of active dz = INH x 9 mos, Alternatively INH x 6 mos or Rifampin x 4 mos
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SE of Rifampin
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Turns body fluids orange
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SE of Ethambutol
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Optic neuritis
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Size of induration that indicates a + PPD test
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? 5 mm: HIV or risk factors, close TB contacts, CXR evidence of TB; ? 10 mm: Indigent/homeless, residents of developing nations, IV drug use, chronic illness, reidents of health ; correctional institutions, health care workers; ? 15 mm: everyone else, including those with no known risk factors
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PPD test with - reaction with - control
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Anergy from immunosuppression, old age, or malnutrition; Does not rule out TB
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How a PPD test is performed
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Injected intradermally on volar surface forearm, Diameter of induration measured at 48-72 hours, BCG vaccinnation usu = +PPD
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Causes of acute pharyngitis
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Viral (90% in adults): Rhinovirus, coronavirus, adenovirus, HSV, EBV, CMV, influenza, Coxsackievirus, acute HIV infection; Bacterial: Group A streptococci (GAS), Neisseria gonorrhoeae, Corynebacterium diptheriae, M. pneumoniae; Impt to identify group A ?-hemolytic Streptococcus pyogenes
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History/PE of typical streptoccocal pharyngitis
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Fever, sore throat, pharyngeal erythema, tonsillar exudate, cervical lymphdenopathy, soft palate petechiae, HA, vomiting, scarlatiniform rash (= scarlet fever)
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History/PE of atypical streptoccocal pharyngitis
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Coryza, hoarseness, rhinorrhea, cough, conjunctivitis, anterior stomatitis, ulcerative lesions, GI sx,
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Centor Criteria
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Used to ID streptococcal pharyngitis, need 3/4: 1. fever, 2. tonsillar exudate, 3. tender anterior cervical LAD, 4. lack of cough
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How to dx step throat
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Clinical evaluation, Rapid GAS antigen detection (w/ 3/4 Centor Criteria, sensitivity ;90%), Throat cx
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How to tx step throat
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PCN x 10 days; Alternative options = cephalosporins, amoxicillins, azithromycin, Symptomatic relief w/ fluids, rest, antyipyretics, ; salt-H2O gargles
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Nonsuppurative complications of strep throat
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Acute rheumatic fever, Poststreptococcal glomerulonephritis
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Suppurative complications of acute pharyngitis
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Cervical lymphadenitis, Mastoiditis, sinusitis, Otitis media, Retropharyngeal or peritonsillar abscess, and rarely Lemierre's syndrome (thrombophlebitis of jugular vein) d/t Fusobacterium
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Dx & tx of peritonsillar abscess
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Sx: odynophagia, trismus ("lockjaw"), muffled voice, unilateral tonsillar enlargement, erythema, w/ uvula & soft palate deviated away from affected side; Dx: localize abscess via intraoral US or CT, culture abscess fluid; Tx: antibiotics & surgical drainage
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Causes of acute sinusitis (sx <1 mo)
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MC associated w/ viruses S. pneumonia, H. influenzae, & M. catarrhalis; bacterial causes are rare and are characterized by sx lasting <1 week
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Causes of chronic sinusitis (sx > 3 mo)
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Represents a chronic inflammatory process, often d/t obstruction of sinus drainage & ongoing low-grade anaerobic infections; In diabetic pts, mucormycosis should be considered
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MC affected sinuses
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Maxillary
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History/PE of sinusitis
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Presents w/ fever, facial pain/pressure, HA, nasal congestion, & discharge; Exam = tenderness, erythema, & swelling over affected area; Bacterial = high fever, leukocytosis, & purulent nasal discharge
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How to dx sinusitis
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Clinical dx - cx & X-ray not required but may guide management of chronic cases; Transillumination shows opacification of sinuses; CT is test for sinus imaging, but only if sx persist after tx; MRI is useful for differentiating soft tissue from mucus; Bacterial cx by sinus tap = gold standard but not routinely performed b/c of discomfort
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Potential complications of sinusitis
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Meningitis, Frontal bone osteomyelitis, Cavernous sinus thrombosis, Abscess formation
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Tx for viral/self-limited aute sinusitis
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Symptomatic therapy (decongestants, antihistamines, pain relief)
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Tx for acute bacterial sinusitis (usu <7 days)
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Amoxicillin/clavulanate 500 mg PO TID x 10 days, Alternatively: clarithromycin, azithromycin, TMP-SMX, fluoroquinolone, or 2nd gen cephalosporin x 10 days
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Tx for chronic sinusitis (4-12 wks)
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Adjuvant tx w/ intranasal corticosteroids, decongestants, & antihistamines; ABs like acute dz (amox/clavulanate 500 mg PO TID) but longer course (3-6 weeks); Surgical intervention possibly
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Pts you would see w/ coccidiodomycosis
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HIV+, Filipino, AA, or pregnant pt from the SW US presenting with respiratory infection
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History/PE of coccidiomycosis
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Presents like acute or subacute pneumonia or flulike illness, may involve extrapulmonary sites including bone, CNS, and skin; FEVER, anorexia, HA, chest pain, COUGH, dyspnea, arthralgias, & NIGHT SWEATS; Disseminated infection can present w/ meningitis, bone lesions, and soft tissue abscesses
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How to dx a coccidiomycosis infection
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BAL w/ fungal cx of sputum, wound exudate, or other affected tissue; ID Coccidioides immitis spherules on H&E; Serology: antibodies: precipitin (IgM): 2 wks-2 mos; complement fixation (IgG) ? at 1-3 mos; titers > 1:16 ? disseminated infection
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CXR findings in coccidiomycosis
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Normal or may show infiltrates, nodules, cavity, mediastinal or hilar adenopathy or pleural effusion
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Location Coccidiomycosis is endemic to
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SW US (San Joaquin Valley, CA)
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Incubation period of Coccidiomycosis
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1-4 wks after exposure
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Tx for acute Coccidiomycosis
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Consider IV Amp B for severe or protracted 1° pulm infection & disseminated dz; PO fluconazole or itraconazole may be used for mild infection or continuation tx when pt stable
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Tx for chronic Coccidiomycosis
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No tx for asymptomatic chronic pulm nodules or cavities; Progressive cavitary or symptomatic dz usu requires surgery + long-term azole tx for 8-12 mos
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Antigenic drift
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Small, gradual ?s in surface proteins through pt mutations; allow virus to escape immune recognition
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Antigenic shift
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Acute, major ? in influenza A subtype (significant genetic reassortment) circulating among humas; leads to pandemics
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Who should get inactivated vaccine for the flu
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>50 yo, children 6 mo - 19 yo, pts any age w/ chronic medical problems (DM, heart dz, renal failure, HIV), pregnant women, Nursing home residents, & contacts of high-risk groups (e.g. health care workers)
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US typical influenza season
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Nov - Mar
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Influenza
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Highly contagious orthomyxovirus transmitted by droplet nuclei; 3 types: A,B,C; Subtypes of A are classified by glycoproteins (hemagglutinin & neuraminidase, eg H5N1)
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History/PE of Influenza
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Abrupt onset of fevers, myalgias, chills, cough, coryza, weakness; Elderly may have atypical presentations characterized only by confusion
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Dx of Influenza
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Often see leukopenia; Nasopharyngeal swab rapid influenza test available; Definitive dx can be made w/ DFA test or viral cx
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Tx of Influenza
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Symptomatic: analgesics & cough medicine; Antivirals (oseltamivir or zanamivir) should be used w/in 2 days of onset, may shorten course by 1-2 days
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Who can get live attenuated, nasally delivered, vaccine for the flu
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Healthy ppl 2-49 yo who are not pregnant or severely immunocompromised
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Complications of influenza
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Severe 1° viral pneumonia, 2° bacterail pneumonia, sinusitis, bronchitis, & exacerbation of COPD & asthma; Reye's syndrome or fatty liver encephalopathy, is associated w/ ASA use in children w/ viral infections
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Risk factors for meningitis
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Recent ear infection, Sinusitis, Immunodeficiencies, Recent neurosurgical procedures, ; sick contacts
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History/PE of Meningitis
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FEVER, malaise, HA, NECK STIFFNESS, PHOTOPHOBIA, AMS, N/V, seizures, or signs of meningeal irritation (+ Kernig's & Brudzinski's signs)
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How to dx meningitis
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Obtain blood cx, LP for CSF Gram stain ; cx (glucose, protein, WBC, RBC, opening pressure), Viral PCRs (HSV), Cryptococcal antigen (for HIV pts), CT or MRI to r/o other dx.
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Causes of Meningitis in newborns (0-6 mos)
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GBS, E. coli/GNRs, Listeria
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Causes of Meningitis in Children (6 mos- 6 yrs)
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S. pneumoniae, Neisseria meningitidis, H. influenzae type b, Enteroviruses
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Causes of Meningitis in 6-60 yo
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N. meningitidis, Enteroviruses, S. pneumoniae, HSV
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Causes of Meningitis in 60+ yo
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S. pneumoniae, GNRs, Listeria, N. meningitidis
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Causes of Meningitis in HIV pts
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Cryptococcus, CMV, HSV, VZV, TB, toxoplasmosis (brain abscess), ; JC virus (PML)
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Normal CSF Profile (RBCs, WBCs, Glucose, Protein, Opening pressure, Appearance, ?-globulin)
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;10 RBCs, ; 5 WBCs, ~2/3 serum Glucose, 15-45 Protein, 10-20 Opening pressure, Clear Appearance, 3-12 ?-globulin
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CSF Profile in Bacterial meningitis (RBCs, WBCs, Glucose, Protein, Opening pressure, Appearance, ?-globulin)
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? RBCs, ? (;1000 PMNs) WBCs, ? Glucose, ? Protein, ? Opening pressure, Cloudy Appearance, ? or ? ?-globulin
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CSF Profile in Viral meningitis (RBCs, WBCs, Glucose, Protein, Opening pressure, Appearance, ?-globulin)
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? RBCs, ? (monos/lymphs) WBCs, ? Glucose, ? or ? Protein, ? or ? Opening pressure, Most often clear Appearance, ? or ? ?-globulin
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CSF Profile in Aseptic meningitis (RBCs, WBCs, Glucose, Protein, Opening pressure, Appearance, ?-globulin)
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? RBCs, ? WBCs, ? Glucose, ? or ? Protein, ? Opening pressure, Clear Appearance, ? ?-globulin
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CSF Profile in SAH (RBCs, WBCs, Glucose, Protein, Opening pressure, Appearance, ?-globulin)
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?? RBCs, ? WBCs, ? Glucose, ? Protein, ? or ? Opening pressure, Yellow/red Appearance, ? or ? ?-globulin
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CSF Profile in Guillain-Barre (RBCs, WBCs, Glucose, Protein, Opening pressure, Appearance, ?-globulin)
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? RBCs, ? WBCs, ? or ? Glucose, ?? Protein, ? Opening pressure, Clear or Yellow (high protein) Appearance, ? ?-globulin
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CSF Profile in MS (RBCs, WBCs, Glucose, Protein, Opening pressure, Appearance, ?-globulin)
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? RBCs, ? or ? WBCs, ? Glucose, ? Protein, ? Opening pressure, Clear Appearance, ?? ?-globulin
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CSF Profile in Pseudotumor Cerebri (RBCs, WBCs, Glucose, Protein, Opening pressure, Appearance, ?-globulin)
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? RBCs, ? WBCs, ? Glucose, ? Protein, ??? Opening pressure, Clear Appearance, ? ?-globulin
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Tx for viral meningitis
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Supportive care, Close f/u
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Tx for close contacts of pts with meningococcal meningitis
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Rifampin, ciprofloxacin, or ceftriaxone prophylaxis
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Drug to be given 15-20 min before antibiotics to tx bacterial meningitis (esp S. pneumoniae)
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Dexamethasone
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Empiric tx of bacterial meningitis in pts ;1 mo
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Ampicillin + cefotaxime or gentamicin (GBS, E.coli/GNRs, Listeria)
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Empiric tx of bacterial meningitis in pts 1-3 mos
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Vancomycin IV + ceftriaxone or cefotaxime (Pneumococci, meningococci, H. influenzae)
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Empiric tx of bacterial meningitis in pts 3 mos - adulthood
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Vancomycin IV + ceftriaxone or cefotaxime (Pneumococci, meningococci)
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Empiric tx of bacterial meningitis in pts ;60 yrs/alcholism/chronic illness
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Ampicillin + Vancomycin IV + ceftriaxone or cefotaxime (Pneumococci, gram - bacilli, Listeria, meningococci)
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Complications of meningitis
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Cerebral edema, Subdural effusions, Ventriculitis/hydrocephalus, Seizures, Hyponatremia, Subdural empyema, Other (Cranial nerve palsies, sensorineural hearing loss, coma, death)
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Dx ; tx cerebral edema d/t meningitis
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Visible on CT/MRI, Presents w/ loss of oculocephalic reflex, Tx with IV mannitol
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Dx ; tx Subdural effusions d/t meningitis
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May see on CT, occurs in 50% infants w/ H. influenzae meningitis, no tx necessary
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Dx ; tx ventriculitis/hydrocephalus d/t meningitis
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Worsening clinical pic w/ improved CSF findings, Requires ventriculostomy ; possible IV antibiotics
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Tx seizures d/t meningitis
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Tx w/ benzodiazepines ; phenytoin
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Tx hyponatremia d/t meningitis
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Administer fluids ; monitor sodium concentration
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Dx ; tx Subdural Empyema d/t meningitis
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Presents w/ intractable seizures, Requires surgical evacuation
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Causes of Encephalitis
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MCC: HSV ; Arboviruses; Rarer etilogies: CMV, toxoplamosis, West Nile virus, VZV, Borrelia, Rickettsia, Legionella, enterovirus, Mycoplasma, ; cerebral malaria; (Children ; the elderly are the most vulnerable)
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History/PE of Encephalitis
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Altered consciousness, HA, fever, ; seizures; lethargy, confusion, coma, ; focal neurologic deficits (CN deficitis, accentuated DTRs) may also be present
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DDx for encephalitis
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Abscess or malignancy, toxic-metabolic encephalopathy, subdural hematoma, SAH
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Dx encephalitis
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CSF shows lymphocytic pleocytosis ; ? protein, RBCs w/o trauma suggests HSV encephalitis, glucose ? in TB, fungal, bacterial, ; amebic infections; CSF Gram stain (bacteria), acid-fast (mycobacteria), India ink (Cryptococcus), wet prep (free-living amebae), ; Giemsa (trypanosomes); PCR (highly sens/spec) for HSV, CMV, EBV, VZV, ; enterovirus
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MRI findings in HSV encephalitis
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Contrast-enhancing lesion in temporal lobe (HSV)
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Tx for encephalitis
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HSV (associated w/ high morbidity): IV acyclovir; CMV: IV ganciclovir +/- foscarnet, Rocky Mt spoted fever, Lyme dz, ehrlichiosis: doxycycline
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Classic clinical triad found in 50% cases of brain abscess
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Headache, Fever, Focal neurologic deficit
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Major ddx of brain mass when fever is absent
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1° ; metastatic brain tumors
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Focal, supurative infection of brain parenchyma, usu w/ "ring enhancing" appearance d/t fibrous capsule
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Brain abscess
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MC infective organisms in brain abscess
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Streptococci, Staphylococci, Anaerobes; Multiple organisms often implicated (80-90% cases are polymicrobial)
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Nonbacterial causes of abscess
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Toxoplasma, Aspergillus, Candida; Zygomycosis in immunocompromised host; Neurocysticercosis in relevant epidemiologic settings
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Modes of transition in brain abscess
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Direct spread, Direct inoculation, hematogenous spread
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Direct spread in brain abscess formation
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Paranasal sinusitis (10% cases, frequently affects young males, often d/t Strep milleri), Otitis media or mastoiditis (33%), or dental infection (2%)
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Direct inoculation in brain abscess formation
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Affects pt w/ h/o head trauma or neurosurgical procedures
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Hematogenous spread
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25% of cases; Often shows MCA distribution w/ multiple abscesses, Poorly encapsulated, Located at gray-white junction
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History/PE in brain abscess
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Early sx: HA (MC sx, dull, constant, refractory to tx), drowsiness, inattention, confusion, seizures; Late: signs of ?ICP ; then focal neurologic deficit (CN III ; VI)
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Dx brain abscess
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CT scan shows ring-enhancing lesion; MRI higher sensitivity for early abscesses ; posterior fossa lesions; CSF analysis not needed, may cause herniation syndrome; Lab values may show peripheral leukocytosis, ?ESR, ?CRP
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Tx brain abscess
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Initiate borad-spec IV antibiotics ; surgical drainage; Third-generation cephalosporin + metronidazole +/- vancomycin; IV therapy for 6-8 wks followed by 2-3 wks PO; Dexamethasone for severe cases to ? cerebral edema; IV mannitol to ?ICP
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Commonly tested AIDS-defining illnesses
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Oropharyngeal/esophageal candidiasis; CMV retinitis; Kaposi's sarcoma; CNS lymphoma, toxoplasmosis, or PM:; PJP or recurrent bacterial pneumonia; Disseminated mycobacterial or funal infection; Invasive cervical cancer
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HIV
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Retrovirus, Targets and destroys CD4+ T lymphocytes
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CD4+ count
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Indicates degree of immunosuppression; guides tx and prophylaxis & helps determine prognosis
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Viral load
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May predict the RATE of HIV dz progression; provides indications for tx & gauges response to antireroviral tx
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History/PE of HV infection
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Acute: often ASYMPTOMATIC, may have MONONUCLEOSIS-LIKE or FLULIKE sx (fever, LAD, maculopapular rash, pharyngitis, diarrhea, N/V, weight loss, HA) Later: night sweatrs, weight loss, thrush, recurent infections, opportunistic infections
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Tests to dx HIV
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ELISA test (high sens, mod spec) detects anti-HIV ABs in bloodstream (can take ? 6 mos to appear); Western blot (low sens, high spec) = confirmatory; Rapid HIV tests
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Baseline evaluation tests for HIV+ pt
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HIV RNA PCR (viral load), CD4+ cell count, CXR, PPD skin testing, Pap smear, VDRL/RPR, & serologies for CMV, hepatitis, toxoplasmosis, & VZV
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Mutation that confers resistance to HIV infection
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CCR5
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Drug to avoid in pregnant HIV+ pts
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Efavirenz
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Tx for pregnant HIV+ pts not on an antiretroviral tx at time of delivery
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Intrapartum Zidovudine (AZT); Infant should receive AZT for 6 wks after birth
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When to initiate antiretroviral tx for HIV+ pt
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1. Symptomatic pts (have AIDS-defining illness) regardless of CD4+ count or viral load; 2. Asymptomatic pts w/ CD4+ count < 350; 3. Pregnant pts; 4. Pts w/ specific HIV-related conditions (e.g., HIV-associated nephropathy)
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Initial HIV+ antiretroviral regimen
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Most importantly use multiple meds (usu ?3) to achieve durable response & limit resistance; Some combo of 2 nucleoside/nucleotide reverse transcriptase inhibitors (RTIs) plus either 1 non-nucleoside RTI (NNRTI) or 1 protease inhibitor
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Goal of HIV+ therapy
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viral suppression (<50 copies), which occurs more rapidly than immune reconstitution
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Only live vaccine that should be given to HIV pts
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MMR (Do not give oral polio vaccine to HIV+ pts or their contacts!)
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AIDS pathogens
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"The Major Pathogens Concerning Complete T-Cell Collapse" Toxoplasma gondii, Mycobacterium avium-intracellulare, Pneumocystis jiroveci, Candida albicans, Cryptococcus neoformans, Tuberculosis, CMV, Cryptosporidium parvum
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Indication & tx for PJP prophylaxis
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CD4+ 200 for ? 3 mos
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Indication & tx for MAC prophylaxis
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CD4+100 for >6 mos
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Indication & tx for Toxoplasma gondii prophylaxis
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CD4+< 100 & + IgG serologies; Tx: double-strength TMP-SMX
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Indication & tx for M. tuberculosis prophylaxis
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PPD > 5 mm or "high risk;" Tx: Sensitive: INH x 9 mos (+ pyridoxine) or rifampin +/- pyrazinamide x 2 mos; (Include pyridoxine w/ INH-containing regimens)
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Indication & tx for Candida prophylaxis
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Multiple recurrences; Tx esophagitis w/ Fluconazole, oral w/ Nystatin swish & swallow
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Indication & tx for HSV prophylaxis
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Multiple recurrences; Tx: Acyclovir, famciclovir, or valcyclovir
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Indication & tx for S. pneumoniae prophylaxis
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All HIV+ pts, give every 5 yrs or when CD4+ <200; Tx: pneumovax
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Indication & tx for Influenza prophylaxis
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All HIV+ pts; Tx: influenza vaccine annually
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Describe appearance of common opportunistic infections
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Candida: Pseudohyphae + budding yeasts, germ tubes @ 37°C; Aspergillus: 45° angle branching septate hyphae, rare fruiting bodies; Cryptococcus: 5-10 µm yeasts w/ wide capsular halo, narrow-based unequal budding; Mucor: irregular broad (empty looking) nonseptate hyphae, wide-angle branching
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Risk factors for Oropharyngeal candidiasis (thrush)
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Xerostomia, antibiotic use, denture use, immunocompromised states (HIV, leukemias, lymphomas, ca, DM, corticosteroid inhaler use, immunosuppressive tx)
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Hx/PE of oropharyngeal candidiasis
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Soft white plaquest that can be rubbed off; Erythematous base & possible mucosal burning; Odynophagia if candidal esophagitis; DDx: oral hairy leukoplakia (lateral borders tongue, not easily rubbed off)
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Dx oropharyngeal candidiasis
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Usu clinical; KOH or gram stain shows budding yeast and/or pseudohyphae
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Tx oropharyngeal candidiasis
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Thrush: Local therapy (Nystatin suspension or clotrimazole tabs, PO azole like fluconazole); Candidal esophagitis w/ PO azole
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Risk factors for Cryptococcal meningitis
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AIDS, exposure to PIGEON DROPPINGS
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Hx/PE of Cryptococcal meningitis, DDx
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HA, fever, impaired mentation, ABSENT MENINGISMUS, DDx: toxoplamosis, lymphoma, TB meningitis, AIDS dementia complex, PML, HSV encephalitis, other fungal dz
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Dx Cryptococcal meningitis
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LP (?CSF glucose, ?protein, ?leukocyte count w/ monocytic predominance, ?? opening pressure); + CSF cryptococcal antigen test; INDIA INK STAIN; fungal cx
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Tx Cryptococcal meningitis
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IV Amphotericin B + flucystosine x 2 wks, Then give fluconazole 400 mg x 8 wks; Lifelong maintenance tx w/ fluconazole 200 mg QD or until CD4+ > 200 for > 6 mos; ? opening pressure may require serial LPs or VP shunt for management
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Highly sensitive & specific test for Cryptococcal meningitis
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CSF antigen test
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Risk factors for Histoplasmosis
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AIDS, spelunking, exposure to bird & bat excrement, Esp in OHIO & MISSISSIPPI RIVER VALLEYS
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History/PE of Histoplasmosis
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1° exposure: asymptomatic or flulike; Presentation ranges from ø sx to fulminant dz w/ pulmonary or extrapulmonary manifestations; Fever, weight loss, hepatosplenomegaly, LAD, nonproductive cough, pancytopenia = disseminated infection (most often w/in 14 days)
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DDx of Histoplasmosis
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Atypical bacterial pneumonias, blastomycosis, coccidioidomycosis, TB, sarcoidosis, pneumoconiosis, & lymphoma
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Dx Histoplasmosis
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CXR: diffuse nodular densities, focal infiltrate, cavity (= chronic), or hilar lymphadenopathy; Urine & serum POLYSACCHARIDE ANTIGEN TEST = most sensitive; Cx diagnostic; Yeast form seen w/ SILVER STAIN on bx or BAL
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Tx of Histoplasmosis
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Mild pulmonary dz or stable nodules: supportively in immunocompromised host; Chronic cavitary lesions: itraconazole for > 1 yr; Severe acute pulmonary dz or disseminated: Amphotericin B x 3-10 days followed by itraconazole x 12 wks or longer, maintenance tx w/ daily itraconazole
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Risk factors for P. jiroveci pneumonia
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Impaired cellular immunity, AIDS
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History/PE of P. jiroveci pneumonia
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DYPSNEA ON EXERTION, NONPRODUCTIVE COUGH, tachypnea, weight loss, fatigue, and IMPAIRED OXYGENATION
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HIV pt w/ nonproductive cough & dyspnea
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Suspect P. jiroveci pneumonia
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DDx of P. jiroveci pneumonia
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TB, histoplasmosis, coccidioidomycosis (PJB can present as disseminated dz or local dz in other organ systems)
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Dx of P. jiroveci pneumonia
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Sputum cytology or bronch specimen w/ silver stain & immunofluorescence; ABG to check PaO2; CXR may show diffuse, BL interstitial infiltrates w/ ground-glass appearance, any presentation possible
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Tx of P. jiroveci pneumonia
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HIGH-DOSE TMP-SMX x 21 days; Clindamycin & primaquine for pts w/ sulfa allergy; Prednisone taper for pts w/ hypoxemia (PaO2 35)
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Transmission of CMV
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Sexual contact, Via breast milk, Respiratory droplets in nursery or day care facilities, Blood tranfusions
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Percent of adults in US infected with CMV
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70%
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Risk factors for CMV reactivation
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first 100 days s/p tissue or bone marrow transplant; HIV+ w/ CD4+ 10,000
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History/PE of CMV
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May resemble EBV mononucleosis; manifests w/ CMV retinitis, GI & hepatobiliary invlovement (bloddy diarrhea, AIDS cholangiopathy), CMV pneumonitis, or CNS involvement (polyradiculopathy, transverse myelitis, subacute encephalitis)
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CMV retinitis
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High rate retinal detachment ("pizza pie" retinopathy), presents w/ floaters & visual field ?s (CD4+ < 50)
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CMV pneumonitis
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Cough, fever, sparse sputum production; High mortality rate; Pts w/ hematologic malignancies/transplant pts > AIDS
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Dx CMV infection
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Virus isolation, cx, tissue examination, serum PCR
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Tx CMV infection
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Ganciclovir or foscarnet; Tx underlying dz if pt is immunocompromised
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Lady Windermere syndrome
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1° form of MAC infection, Occurs in apparently health non-smokers
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2° pulmonary form of MAC
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affects pts w/ preexisting pulmonary dz such as COPD, TB, or CF
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History/PE of Mycobacterium avium Complex (MAC)
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Disseminated infection occurs in AIDS pts w/ CD4+ <50, associated w/ fever, eakness, weight loss in pts who are not on HAART or chemoprophylaxis for MAC; Hepatosplenomegaly & LAD are occasionally seen; Adrenal insufficiency is possible if infiltrates adrenals
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Dx MAC
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Obtain mycobacterial blood cx (+ in 2-3 wks); Labs show anemia, hypoalbuminemia, ? serum alk phos & LDH; Bx of bone marrow, intestine or liver reveals foamy macrophages w/ acid fast bacilli
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Tx MAC
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Clarithromycin & ethambutol +/- rifabutin & HAART; Continue for >12 mos & until CD4+ >100 for >6 mos
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Prevention for MAC
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Weekly azithromycin for those w/ CD4+ <50 or AIDS defining opportunistic infection
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Risk factors for Toxoplasmosis
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Ingesting raw or undercooked meat; Changing cat liver; Exposure highest in France
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History/PE of Toxoplasmosis
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1° infection asymptomatic; Reactivated in immunosuppressed, may present in specific organs (brain, lung, eye > heart, skin, GI tract, liver); Encephalitis common in seropositive AIDS pts (fever, HA, AMS, seizures, focal neurologic deficits)
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Dx Toxoplasmosis
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Serology, PCR; With CNS involvement obtain CT (multiple isodense or hypodense, ring-enhancing mass lesions) or MRI (more sensitive for predilection for basal ganglia)
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Tx of Toxoplasmosis
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Induction w/ hgih-dose PO pyrimethamine + sulfadiazine & leukovorin x 4-8 wks; Maintenance w/ low-dose same until dz resolved clinically & radiographically; TMP-SMX or pyrimethamine + dapson can be used for prophylaxis in pts w/ CD4+ < 100 and a + toxoplasmosis IgG
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Two most likely differential diagnoses of ring-enhancing lesions in AIDS pts
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Toxoplasmosis CNS lymphoma
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MC bacterial STD in the US
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Chlamydia trachomatis
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Risk factors for Chlamydia
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Unprotected sexual intercourse, New or multiple partners, Frequent douching
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Common cause of nongonoccocal urethritis in men
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Chlamydia infection
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History/PE of Chlamydia
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Often asymptomatic, may present w/ URETHRITIS, MUCOPURULENT CERVICITIS, or PID; women: cervical/adnexal tenderness; men: penile d/c & testicular tenderness; May infect genital tract, urethra, anus, & eye
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Ddx of Chlamydia
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Gonorrhea, Endometriosis, PID, Orchitis, Vaginitis, UTI
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Lymphogranuloma venereum
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CAused by LGV serovars of Chlamydia; 1° form = painless, transient papule or shallow ulcer; 2° form = painful swelling of the inguinal nodes; 3° form = "anogenital syndrome" = anal pruritus w/ d/c, rectal strictures, rectovaginal fistula, & elephantitis
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Dx of Chlamydia
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Usu clinical; Cx = gold standard; Urine tests (PCR or ligase chain reaction) = rapid means of detection, DNA probes & immunofluorescence take 48-72 hrs; Gram stain = PMNs but no bacteria (intracellular)
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Complications of chlamydia
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Arthritis, Neonatal conjunctivitis, Pneumonia, Nongonococcal urethritis/PID (? ectopic pregnancy/infertility), lymphogranuloma venereum
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Tx of chlamydia
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Doxycyclin 100 mg PO BID x 7 days, Or Azithromycin 1 g PO x 1 day; Use Erythromycin in pregnant pts; Tx sexual partners & maintain low threshold to tx for N. gonorrhoeae; LGV serovars require prolonged tx for 21 days
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Reiter's syndrome
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urethritis, conjuncitivits, arthritis; Complication of Chlamydia infection
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Fitz-Hugh-Curtis syndrome
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Perihepatic inflammation ; fibrosis; Complication of Chlamydia infection
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Gram stain Gonorrhea
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Gram -, intracellular diplococcus
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History/PE of Gonorrhea infection
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Females: infect reproductive tract, GREENISH-YELLOW D/C, pelvic or ADNEXAL PAIN, swollen Bartholins glands; Males: limited to urethra, PURULENT URETHRAL D/C, dysuria, ; erythema of urethral meatus
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Ddx of Gonorrhea
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Chlamydia, Endometriosis, Pharyngitis, PID, Vaginitis, UTI, Salpingitis, Tubo-ovarian abscess
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Dx Gonorrhea
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Gram stain ; cx = gold standard; Nucleic acid amplification tests can be sent from penile/vaginal tissue or from urine
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Sx of disseminated Gonorrhea infection
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Monoarticular septic arthritis, Rash, Tenosynovitis
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Tx for Gonorrhea
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Ceftriaxone IM or cefepime PO x 1 dose; Also tx for presumptive chlamydia coinfection (doxycycline x 7 days or macrolide (azithromycin) x 1 dose); Disseminated dz requires IV Ceftriaxone ? 24 hrs
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Complications of Gonorrhea
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Persistent infection w/ pain; Infertility; Tubo-ovarian abscess w/ rupture; Disseminated gonococcal infection
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The "great imitator"
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Syphilis, b/c dermatologic findings resemble those of many other diseases
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Cause of syphilis
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Treponema pallidum, a spirochete
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History/PE of primary syphilis
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(10-90 days after infection): painless ulcer (chancre)
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History/PE of secondary syphilis
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(4-8 wks after chancre): low-grade fever, HA, malaise, LAD, diffuse, symmetric, nonpruritic MACULOPAPULAR RASH ON SOLES ; PALMS, condylomata lata (highly infectious)
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History/PE of latent syphilis
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Early latent: (period from resolution of 1° or 2° syphilis to end of FIRST YEAR of infection): no sx, + serology; Late latent: (period of asymptomatic infection ;1st yr)
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History/PE of tertiary syphilis
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(1-20 yrs after initial infection): GUMMAS, NEUROSYPHILIS, TABES DORSALIS (post column degeneration), meningitis, ARGYLL ROBERTSON PUPIL (constricts w/ accommodation but not reactive to light), CV findings (AORTIC ROOT ANEURYSMS)
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Dx syphilis
answer
Dark field micorscopy (motile spirochetes), VDRL/RPR (rapid, cheap, sens only 60-75% in 1°), FTA-ABS (sens ; specific, used as 2° dx test), T. pallidum particle agglutination test (TPPA, sens ; spec similar to FTA-ABS but easier to use)
