Immunocompromised Hosts (Kays) Flashcards

1
Q

Define “neutropenia”.

A

abnormal reduction in the number of neutrophils circulating in peripheral blood

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2
Q

What ANC count qualifies as neutropenic?

A

< 1000/mm3

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3
Q

How do you calculate ANC?

A

ANC = WBC x (% polys + % bands)

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4
Q

There is a high risk of infection in patients with ANC < ______ cells/mm3

A

500

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5
Q

Risk of infection and death are greatest in patients with ANC < ____ cells/mm3.

A

100

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6
Q

Patients with severe neutropenia for more than _________ days are at high risk for serious infections.

A

7-10

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7
Q

What bacteria are most common in neutropenia?

A
  • S. aureus
  • S. epidermidis
  • streptococci
  • enterococci
  • E. coli
  • K. pneumoniae
  • P. aeruginosa
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8
Q

What fungi are most common in neutropenia?

A
  • Candida
  • Aspergillus
  • Zygomycetes (Mucor, Rhizopus)
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9
Q

What virus is most common in neutropenia?

A

herpes simplex virus (HSV)

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10
Q

Defects in T-lymphocyte and macrophage function are related to what type of immunity?

A

cell-mediated immunity

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11
Q

What type of immunity is negatively impacted by underlying disease (Hodgkin’s lymphoma) or immunosuppressive drug therapy in transplant patients?

A

cell-mediated immunity

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12
Q

Defects in T-lymphocyte and macrophage function result in reduced ability of the host to defend against ____________ pathogens.

A

intracellular

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13
Q

What bacterial pathogens are implicated in defects in T-lymphocyte and macrophage function (cell-mediated immunity)?

A
  • Listeria
  • Nocardia
  • Legionella
  • Mycobacteria
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14
Q

What fungal pathogens are implicated in defects in T-lymphocyte and macrophage function (cell-mediated immunity)?

A
  • C. neoformans
  • Candida
  • Histoplasma capsulatum
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15
Q

What viral pathogens are implicated in defects in T-lymphocyte and macrophage function (cell-mediated immunity)?

A
  • CMV
  • VZV
  • HSV
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16
Q

What protozoal pathogen is implicated in defects in T-lymphocyte and macrophage function (cell-mediated immunity)?

A

Pneumocystis jiroveci

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17
Q

Defects in B-cell function are related to what type of immunity?

A

humoral immunity

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18
Q

Underlying disease (multiple myeloma, chronic lymphocytic leukemia), splenectomy, and immunosuppressive therapies (steroids, chemotherapy) can all lead to which defects?

A

defects in B-cell function (humoral immunity)

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19
Q

What bacterial pathogens (encapsulated) are implicated in defects in B-cell function (humoral immunity)?

A
  • S. pneumoniae
  • H. influenzae
  • N. meningitidis
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20
Q

What pathogens are implicated in destruction of the skin as a protective barrier?

A
  • S. aureus
  • S. epidermidis
  • Candida species
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21
Q

What bacterial pathogens are implicated in the destruction of mucus membranes of the oropharynx and GI tract as protective barriers?

A
  • S. aureus
  • S. epidermidis
  • Enterobacteriaceae
  • streptococci
  • P. aeruginosa
  • Bacteroides species
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22
Q

What fungal pathogens are implicated in the destruction of mucus membranes of the oropharynx and GI tract as protective barriers?

A

Candida species

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23
Q

What viral pathogen is implicated in the destruction of mucus membranes of the oropharynx and GI tract as protective barriers?

A

HSV

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24
Q

What bacterial pathogens are implicated in solid organ transplant?

A
  • S. aureus
  • S. epidermidis
  • Enterobacteriaceae
  • P. aeruginosa
  • Bacteroides species
25
Q

What fungal pathogens are implicated in solid organ transplant?

A

Candida species

26
Q

What viral pathogen is implicated in solid organ transplant?

A

HSV

27
Q

What is the most common colonization site for infection in cancer patients?

A

GI tract

28
Q

Bacteremias are caused predominantly by normal gut flora, and develop as a result of ____________________________.

A

microbial translocation across injured GI mucosa

29
Q

Oropharyngeal flora rapidly change to primarily ______________ in hospitalized patients.

A

Gram-negative bacilli

30
Q

Febrile episodes in neutropenic cancer patients are attributed to _____________ documented infection in only 30-40% of cases.

A

microbiologically

31
Q

45-70% of bacteremic episodes in cancer patients are due to ______________.

A

Gram-positive cocci

32
Q

Why are 45-70% of bacteremic episodes in cancer patients are due to gram-positive cocci?

A
  • use of indwelling central/peripheral IV catheters
  • use of broad spectrum antibiotics with poor gram-positive activity
  • higher rates of mucositis caused by aggressive cancer treatments
  • prophylaxis with Bactrim or fluoroquinolones
33
Q

What is the primary risk factor for invasive aspergillosis?

A

prolonged neutropenia

34
Q

Invasive Aspergillus infection is seen primarily in patients with ______________ and undergoing ________________.

A

hematologic malignancies; HSCT

35
Q

Aspergillus is acquired by inhalation of airborne _______.

A

spores

36
Q

What is the most important clinical finding of infection in neutropenic cancer patients?

A

fever

37
Q

In order for a neutropenic cancer patient to be considered low-risk for infection, what criteria must be met?

A
  • neutropenia for 7 days or less
  • no/few comorbidities
  • clinically stable at onset of fever
  • no identified focus of infection or simple infection (e.g., UTI)
38
Q

In order for a neutropenic cancer patient to be considered high-risk for infection, what criteria must be met?

A

profound (ANC ≤ 100 cells/mm3 ) AND prolonged neutropenia (> 7 days) and/or significant commodities (hypotension, pneumonia, new-onset abdominal pain, neurologic changes)

39
Q

What regimen should be given for initial management of febrile neutropenia in low-risk patients with adequate outpatient infrastructure who are candidates for an oral regimen?

A

oral FQ + Augmentin

40
Q

What regimen should be given for initial management of febrile neutropenia in low-risk patients with inadequate outpatient infrastructure who are not candidates for an oral regimen?

A

Inpatient IV antibiotics (monotherapy)

  • Zosyn
  • antispeudomonal carbapenem
  • cefepime
  • ceftazidime
41
Q

What regimen should be given for initial management of febrile neutropenia in high-risk patients?

A

Inpatient IV antibiotics (monotherapy)

  • Zosyn
  • pseudomonal carbaoenem
  • cefepime
  • ceftazidime
42
Q

What should be added to initial febrile neutropenia treatment in high-risk patients with cellulitis, pneumonia, severe sepsis/shock, gram-positive bacteremia, suspected IV catheter infection, known MRSA colonization, or resistant streptococci?

A

IV vancomycin

43
Q

What should be added to initial febrile neutropenia treatment in high-risk patients with septic shock, gram-negative bacteremia, or pneumonia?

A

aminoglycoside or antipseudonomal fluoroquinolone

44
Q

What are the options for beta-lactam monotherapy as an empiric antibiotic regimen for febrile neutropenia?

A
  • ceftazidime 2 g q8h
  • cefepime 2 g q8h
  • Zosyn 4.5 g q6h
  • imipenem 500 mg q6h
  • meropenem 1 g q8h
45
Q

Does the IDSA recommend vancomycin or other gram-positive agents as a standard part of the initial antibiotic regimen for febrile neutropenia?

A

no

46
Q

What are some situations that would warrant the addition of gram-positive agents to an empiric regimen for febrile neutropenia?

A
  • hemodynamic instability/other evidence of severe sepsis
  • radiographically documented pneumonia
  • positive blood cultures for gram-positive pathogen before final identification and susceptibility test results are known
  • clinically suspected serious catheter-related infection (e.g. cellulitis around the catheter entry/exit site)
  • skin/soft tissue infection at any site
  • colonization with MRSA, VRE, or PRSP
  • severe mucositis (if FQ prophylaxis has been given or if ceftazidime used as empiric therapy)
47
Q

What is the preferred empiric regimen for febrile neutropenia in penicillin-allergic patients?

A

ciprofloxacin + aztreonam + vancomycin

48
Q

In febrile neutropenia, we should re-evaluate the clinical status of the patient after _________ of empiric antimicrobial therapy.

A

48-72 hrs

49
Q

What therapy additions can be considered if a febrile neutropenia patient is found to have MRSA after empiric therapy?

A
  • vancomycin
  • linezolid
  • daptomycin
50
Q

What therapy additions can be considered if a febrile neutropenia patient is found to have VRE after initiation of empiric therapy?

A
  • linezolid
  • daptomycin
51
Q

What therapy additions can be considered if a febrile neutropenia patient is found to have an ESBL producer after initiation of empiric therapy?

A

carbapenem

52
Q

What therapy additions can be considered if a febrile neutropenia patient is found to have a KPC producer after initiation of empiric therapy?

A
  • ceftazidime/avibactam
  • meropenem/vaborbactam
  • imipenem/cilastatin/relebactam
53
Q

In febrile neutropenia, persistence of fever or development of new fever during broad-spectrum antibacterial therapy may indicate the presence of a __________ infection.

A

fungal

54
Q

What two viruses should be evaluated in neutropenic patients with vesicular or ulcerative skin or mucosal lesions?

A

HSV or VZV

55
Q

What drug should be initiated if a neutropenic patient is found to have HSV/VZV?

A

acyclovir

56
Q

What drug should be initiated in a neutropenic patient found to have CMV?

A

ganciclovir

57
Q

What is the most important determinant of patient outcomes in febrile neutropenia?

A

resolution of neutropenia

58
Q

Annual influenza vaccination with _________ vaccine is recommended for all neutropenic patients.

A

inactivated