Rosen & Barkin's 5-Minute Emergency Medicine Consult (491 page)

• Occurs in HIV patients when the CD4 T-lymphocyte count falls below 200 cells/mm
  ³
  or <14% of the total lymphocyte count:
  
  • Pneumocystis jiroveci
    pneumonia (PCP)
    
  • Disseminated tuberculosis
    
  • Cryptosporidiosis
    
  • Microsporidiosis
    
  • Isosporiasis
    
  • Toxoplasmosis
    
  • Histoplasmosis
    
  • Cryptococcosis
    
  • Mycobacterium avium
    complex
    
  • Tuberculosis pericarditis or meningitis
    
  • Cytomegalovirus
    
  • Human herpesvirus-8 (Kaposi sarcoma)
    
  • JC virus (progressive multifocal leukoencephalopathy)
    
  • Hepatitis B virus
    
  • Penicilliosis marneffei
    
  • Bacterial species
    
• Cell-mediated deficiency:
  
  • Hematologic malignancies
    
  • Lymphoma
    
  • High-dose glucocorticoid therapy
    
  • Autoimmune disorders
    
  • Viral infections
    
  • Cytotoxic drugs/chemotherapy
    
  • Radiation therapy
    
  • Associated with:
    
    • Legionella
      
    • Nocardia
      
    • Salmonella
      
    • Mycobacteria
      
• Neutrophil impairment/depletion:
  
  • Cytotoxic drugs
    
  • Aplastic anemia
    
  • Drug reactions:
    
    • Dapsone
      
  • Neoplastic invasion of bone marrow
    
  • Arsenic
    
  • Penicillin
    
  • Chloramphenicol
    
  • Procainamide
    
  • Vitamin deficiencies
    
  • Associated with:
    
    • Staphylococcus
      and α-hemolytic
      Streptococcus
      
    • Enteric organisms and anaerobes
      
    • Invasive aspergillosis
      

DIAGNOSIS

• New or worsening fatigue
  
• Tachypnea
  
• Fever
  
• Chills
  
• Night sweats
  
• Pulmonary source of infection:
  
  • Cough
    
  • Congestion
    
  • Rales
    
• Genitourinary source of infection:
  
  • Dysuria
    
  • Increased frequency
    
  • Urinary retention
    
• GI source of infection:
  
  • Abdominal pain
    
  • Vomiting
    
  • Diarrhea
    
  • Bleeding
    
  • Jaundice
    
• CNS sources of infection:
  
  • Confusion
    
  • Focal neurologic deficits
    
  • Headache
    
  • Seizure
    

• History for HIV/AIDS (recent CD4 count)
  
• History of malignancy with active treatment
  
• History of organ transplant
  
• History of autoimmune disorder
  
• Use of cytotoxic drugs
  
• Use of high-dose glucocorticoid therapy
  

• Complete, detailed physical exam indicated as signs of infection in the immunocompromised patient may be subtle.
  
• Signs of systemic inflammatory response syndrome:
  
  • Temperature >38°C or <36°C
    
  • Heart rate >90 bpm
    
  • Respiratory rate >20 breaths per minute or PCO
    ₂
    <32 mm Hg
    
• Septic shock
  
• Focal neurologic deficits
  
• New murmur
  
• Ambulatory hypoxia in PCP pneumonia
  
• Rales and/or rhonchi in pneumonia
  
• Skin/mucosa defects as a portal of entry.
  
• Oropharyngeal candidiasis as an indicator of immune suppression
  

Full workup indicated owing to impaired immunity:

• Signs of infection in the immunocompromised patient may not be present
  
• Can present with subtle signs with rapid deterioration
  
• Signs such as fever must lead to a full evaluation of patient
  
• Thorough physical exam is critical to search for source of infection
  

• CBC with differential for neutropenia or leukocytosis:
  
  • WBC >12,000 or <4,000 are criteria for the systemic inflammatory response score
    
  • Neutropenia:
    
    • Absolute neutrophil count (ANC) <1,500/μL
      
    • ANC = WBC (cells/μL) × percent (PMNS + bands)/100
      
• Cultures (aerobic, anaerobic, fungal, viral as indicated):
  
  • Urine
    
  • Blood
    
  • Wound
    
  • Fecal
    
  • CD4 count:
    
    • Absolute lymphocyte count (ALC) <1,000/μL predicts CD4 <200 if CD4 unknown
      
    • ALC = WBC (cells/μL) × percent lymphocytes/100
      
• Urinalysis for presence of WBC, nitrite, leukocyte esterase
  
• Electrolytes, BUN/creatinine, glucose; anion gap acidosis suggests severe infection
  
• VBG for acidosis
  
• Lactate level; elevated value suggests serious infection
  
• PT/PTT for evidence of disseminated intravascular coagulation
  
• Lactate dehydrogenase (LDH); elevated in patients with PCP
  

• CXR:
  
  • Nonspecific for predicting a particular infectious etiology
    
  • Pneumonia:
    
    • Segmental or subsegmental infiltrate
      
    • Air bronchograms
      
    • Abscess
      
    • Cavitation
      
    • Empyema
      
    • Pleural effusion
      
  • PCP:
    
    • Classically reveals bilateral interstitial or central alveolar infiltrates
      
    • Radiograph normal in up to 25% of patients
      
• High-resolution chest CT:
  
  • Early studies show high sensitivity for PCP in HIV-positive patients
    
  • Reveals patchy ground-glass attenuation
    
  • Head CT: Contrast-enhancing lesions in
    Toxoplasma gondii
    encephalitis
    
• Abdominal and pelvic CT with contrast:
  
  • Indicated if a GI source of infection is suggested by the clinical exam
    

Lumbar puncture:

• CSF analysis if signs of CNS infection
  
• Diagnostic paracentesis:
  
• Immunocompromised liver patients for SBP
  

TREATMENT

• Check airway, breathing, and circulation
  
• Initiate 0.9% normal saline IV 500 mL bolus for hypotension
  
• Oxygen
  
• Cardiac monitor for unstable vital signs
  
• Early initiation of antibiotic therapy
  

• Strict isolation
  
• Antibiotics: Combination of expanded-spectrum penicillin (mezlocillin, ticarcillin, piperacillin) and aminoglycoside (amikacin, tobramycin):
  
  • Monotherapy with a 3rd-generation cephalosporin (ceftazidime, cefepime), fluoroquinones (levofloxacin, gatifloxacin), or other broad-spectrum antimicrobials (imipenem/cilastatin) may be considered if aminoglycosides contraindicated
    
  • Vancomycin if there is a high prevalence of methicillin-resistant organisms in the area
    
  • Antifungals (amphotericin B, fluconazole) if patient is on adequate antibiotics for 1 wk
    
  • Trimethoprim/sulfamethoxazole for suspected PCP (alternatives: Pentamidine, clindamycin + primaquine)
    
• Steroids: Prednisone in PCP with hypoxemia
  

• Amphotericin B: 0.25 mg/kg/d IV
  
• Cefepime: 1–2 q12h IV
  
• Ceftazidime:
  
  • Adults: 1–2 g IV q8–12h
    
  • Pediatric: 100–150 mg/kg/24h IV q8–12h
    
• Fluconazole: 400 mg 1st dose, then 200–400 mg/d IV (peds: 6–12 mg/kg/24h IV q12h)
  
• Gatifloxacin: 400 mg/d IV
  
• Imipenem/cilastatin: 500–1,000 mg IV q6–8h, max. 50 mg/kg/d or 4,000 mg/d
  
• Levofloxacin: 500 mg/d IV
  
• Vancomycin: 1–2 g IV q12h (peds: 10–50 mg/kg/24h IV q6h
  
• Trimethoprim: 15–20 mg/kg + sulfamethoxazole: 75 mg/kg PO or IV div. q8h
  
• Prednisone: 40 mg PO BID × 5 days, then 40 mg PO QD × 5 days, then 20 mg PO QD × 11 days
  

*start within 72 hr of antimicrobials for PCP

FOLLOW-UP

Suspected or confirmed systemic infection

Systemic infection excluded

Consider infectious disease consultation

Patients with systemic opportunistic infections should be admitted to the hospital

• Signs of infection in the immunocompromised patient may not be present
  
• Can present with subtle signs with rapid deterioration
  

• Fishman JA. Infection in solid-organ transplant recipients.
  N Engl J Med
  . 2007;357(25):2601–2614.
  
• Kaplan JE, Benson C, Holmes KK, et al. Guidelines for prevention and treatment of opportunistic infections in HIV-infected adults and adolescents: Recommendations from CDC, the National Institutes of Health, and the HIV Medicine Association of the Infectious Diseases Society of America.
  MMWR Recomm Rep
  . 2009;58(RR-4):1–207; quiz CE1–4.
  
• Rothman RE, Marco CA, Yang S. AIDS and HIV infection. In: Marx JA, ed.
  Rosen’s Emergency Medicine
  . 7th ed. Boston, MA: Elsevier; 2009:130.
  
• Shapiro NI, Karras DJ, Leech SH, et al. Absolute lymphocyte count as a predictor of CD4 count.
  Ann Emerg Med
  . 1998;32(3):323–328.
  
• Tan IL, Smith BR, von Geldern G, et al. HIV-associated opportunistic infections of the CNS.
  Lancet Neurol
  . 2012;11(7):605–617.