Lecture 21: Infections in Immunocompromised

Question 1

For infections, why is there usually a delayed diagnosis in immunocompromised patients?

Answer 1

An impairment in the inflammatory response results in diminished symptoms and atypical presentation

Question 2

Name the 3 examples of humoral defense mechanisms.

Answer 2

Immunoglobulins
B lymphocytes
Complement system

Question 3

Infections associated with barrier injury: what are the organisms commonly seen with damaged skin?

Answer 3

Coagulase negative Staphylcocci
S. aureus

Central line related infex (Gram negative organisms; Candida sp.)

Question 4

What organisms are commonly seen in oral mucositis?

Answer 4

Streptococcus sp.; anaerobes

H influenze, N meningitidis

Question 5

What common organism are seen in GI mucosal barrier injury?

Answer 5

Gram negative rods, anerobes,

micro-aerophilic streptococci, enterococci

Question 6

What organisms are typically seen in patients with antibody defects?

Answer 6

Encapsulated Organisms: Strep pneumoniae, N meningitidis, H influenzae

Enterovirus

Giardia

Question 7

What organisms are typically seen in patients with complement defects?

Answer 7

Encapsulated organisms

Question 8

What infectious organisms are associated with defects macrophages?

Answer 8

Fungi: Cryptococcus, Histo, Pneumocystis

Protozoa: Toxoplasma

Bacteria: Legionella

Parasites: Strongyloides

Question 9

What infectious organisms are associated with defects in cytotoxic T-cells?

Answer 9

Viruses: CMV, HCV, EBV, HSV, VZV

Question 10

Define Neutropenic Fever

Answer 10

Fever: single temp >38.3 C or sustained temp >38 C for 1 hour or more.
Neutropenia: ANC less than 500

Question 11

What are the common gram positive organisms seen in neutropenic patients?

Answer 11

• Coag. Negative Staph (7-51%)
• Staph aureus
• Enterococcus species, like VRE
• Strep pneumoniae
• Strep pyogenes

(Mortality @ 5%)

Question 12

What are the common gram negative organisms seen in neutropenic patients?

Answer 12

• Enterobacteriaceae (8-50%)
• Psudomonas aerginosa (28%)
• Actinobacter
• Stenotrophomonas maltophilia

(Mortality @ 18%)

Question 13

What is the most important risk factor for infections in cancer patients?

Answer 13

Neurtropenia is the most important risk factor

Other RFs - Mucositis (infection w/oral flora or gut flora)
which predisposes to bloodstream infections

Question 14

What organisms are associated with Ecthyma Gangreonosum?

Answer 14

Psudomonas aerginosa
Staph aureus
Fungi: candida, Aspirgillus, zygomycosis

Question 15

When are anaerobes more likely an infectious cause in neutropenic patients?

Answer 15

Post abdominal sugery/ileus, GI abscesses

+ C. Diff associated with antibiotic use

Question 16

On a chest CT scan, you see what looks like ground class infiltration, so called a “Halo sign”; what is this a major concern for?

Answer 16

Fungal pneumonia

Question 17

What are the most common fungal infections in cancer patients?

Answer 17

Candida sp. (Central lines, mucositis, causes bacteremia)

Aspergillus sp. (seen in blood malignancies + neutropenia, respiratory infxs)

Pneumocystis jirovecii (pneumonia infxs)

aaaaand Cyptococcus, zygomycosis, Fusarium

Question 18

Describe patients w/ neutropenia that are high risk patients.

Answer 18

> 7 days + profound neutropenia ( less than 100)

Question 19

In high risk patients w/ neutropenic fever, what are the 3 steps of treatment?

Answer 19

1. ) Prompt anti-gram neg antibiotics by IV (antipseudomonal, cefepime, piperacillin, carbapenem)
2. ) Consider vanco - indwelling line, hypotension, pneumonia, skin infxs
3. ) Add anti-fungals if persistant fever (4-7 days) post therapy

Question 20

In low risk patients w/ neutropenic fever, what is the main treatment?

Answer 20

Oral antibiotics (cipro + amoxicillin/clavulante)

Question 21

Between 4 weeks and 6 months post organ transplant, what kinds of infections are patients at high risk for?

Answer 21

Opportunistic, relapsed, residual infections (cause it’s the period of most intensive immunosupporession)

Question 22

In the first 4 weeks post organ transplant, what infections are patients most at risk for?

Answer 22

Nosocomial infections (Hospital Associated Infxs)