M34: Opportunistic Infections Flashcards
Immunocompromise and opportunistic infection:
- An immunocompromised person is deficient in a mechanism(s) required for complete _
- An opportunistic pathogen is defined as one that exists in the _ and _.
a. can be (4).
b. Disease can be caused by _ or _ with an opportunistic pathogen
- protection against a pathogen
- environment (or even the host)
does not usually cause disease in a immunocompetent host
a. bacteria, parasites, fungi, or viruses
b. initial infection or reactivation of previous infection
Types of immunocompromised:
Barrier impairment/damaged integument
a. Normal barrier (_, _) is broken so microorganisms can enter (2)
b. Nosocomial infections are often the result of _ impairment (e.g. _-related infections)
c. Examples of infections associated with skin barrier impairment (e.g. intravenous catheter) (4)
a. skin, mucosa
i. burn wounds
ii. catheter
b. barrier
catheter
c.
- Coagulase negative staphylococci
- Pseudomonas aeruginosa
- Acinetobacter
- Candida
Types of immunocompromised:
Changes in ability to physically clear bacteria
a. An example is (bacteria) lung infections due to _ (lung cannot clear bacteria due to mucus production)
b. _: changes in complement components, antibodies, resulting in loss of _ function: susceptible to severed infections with (bacteria, bacteria)
a. Pseudomonas aeruginosa
cystic fibrosis
b. Splenectomy
phagocytic
Streptococcus pneumoniae, Haemophilus influenzae
Types of immunocompromised:
Loss of specific immune function due to inherited defect
a. Mutations are usually (dominant / recessive), several are _ linked. Most are in (innate / adaptive), not (innate / adaptive), immunity.
b. With a loss of B cells or helper T cells, _ are not made.
i. Infections with (intracellular / extracellular) bacteria are common
ii. Pyogenic bacteria and encapsulated bacteria cause infections in these immunocompromised patients. (3)
a. recessive
X-chromosome
adaptive
innate
b. antibodies
i. extracellular
ii.
- Streptococcus pneumoniae
- Staphylococccus
- Haemophilus influenzae
Types of immunocompromised:
Loss of specific immune function due to inherited defect
c. Loss of (B / T) cells (all or one subset) usually more severe immuno-compromise than loss of (B / T) cells. Infections with _, _, and _ are seen.
Herpes virus infections: • (4) • (1) • Respiratory viruses (2) (5)
c. T
B
bacteria, viruses, fungi
- HSV, zoster, Epstein Barr Virus, cytomegalovirus
- Adenovirus
- Respiratory viruses (RSV, influenza)
- Listeria monocytogenes
- Mycobacterial infections
- Pneumocystis
- Cryptococcus
- Histoplasma
Types of immunocompromised:
Loss of specific immune function due to inherited defect
d. Loss of _ cell function results in infections with microorganisms that are usually controlled by _ or _
i. Examples: bacteria: (2)
ii. Example: fungi: (1)
e. _ deficiency also a genetic
mutation. These patients are susceptible to _ infections.
d. phagocytic
macrophage or neutrophils
i. Staphylococcus aureus, Serratia marcescens
ii. Aspergillus
e. Complement (C5-9, membrane attack complex)
Neisseria
Types of immunocompromised:
Infection with another pathogen
a. Acute infection with some pathogens can cause (transient / long-lasting) and (mild / severe) immunosuppression, leading to _ infections (e.g. measles)
b. Treatment with antibiotics can result in increased _, e.g. yeast infections
c. Physical changes (chancre sores, viral respiratory infections) provide _ for other pathogens.
a. transient
mild
secondary
b. proliferation of other normal flora
c. entry sites
Types of immunocompromised:
Infection with another pathogen
d. _ infection eventually causes widespread immunosuppression
i. loss of _ cells, changes in _ regulation
ii. Infections are primarily those that are usually controlled by _
iii. Opportunistic and standard pathogens cause disease in _ patients.
Examples: (9)
d. HIV
i. CD4 T
cytokine
ii. CMI
iii. AIDS
- Mycobacterium tuberculosis
- Mycobacterium avium
- Candida
- Varicella zoster virus
- Pneumocystis (carinii) jiroveci
- Cryptococcus neoformans
- Cytomegalovirus
- Histoplasma capsulatum
- Toxoplasma gondii
Types of immunocompromised:
Treatment with immunosuppressive drugs or regimens predisposes patients to opportunistic infections (often granulocytopenia)
a. _ with chemotherapy or irradiation, causing granulocytopenia
b. _ drugs used in treatment of malignant diseases
c. The immunosuppressive regimen causes _ and diminished functioning of _ cells, in addition to diminished _-mediated immunity.
d. loss of function of _ can occur with treatment regimens
e. Granulocyte deficiency can result in (3)
f. most common pathogens associated with granulocytopenia (6)
a. Transplants (bone marrow and organ)
b. cytotoxic
c. neutropenia
phagocytic
cell
d. granulocytes
e. local infection, disseminated infection, sepsis
f.
- Staphylococcus aureus
- Coagulase negative staphylococci
- Streptococcus
- Enerococcus
- E. coli
- Aspergillus
Types of immunocompromised:
- Immunocompromise due to _ leads to an increase in susceptibility to opportunistic infections in the _ and _.
- Immunocompromise due to _ or _
- Eg stress-associated reactivation of _ = _ - Other factors
- _ (malignant lymphoma): impaired _ immunity
- age
elderly and infants - stress or malnutrition
varicella zoster virus = shingles - Hodgkin’s disease
cellular
Common opportunistic infections in immunocompromised patients:
Viral (2)
Bacterial (6)
Protozoal (3)
Fungal (6)
Herpes Simplex
Cytomegalovirus (CMV)
Pseudomonas sp. Staphylococcus aureus Streptococcal sp. Haemophilus influenzae Escherichia coli Mycobacterium sp.
Toxoplasma gondii
Cryptosporidium
Microsporidium
Aspergillus Candida Pneumocystis carinii Histoplasma capsulatum Coccidiodes immitis Cryptococcus
Opportunistic infections in immunocompromised patients:
Reactivation of latent infections can lead to disease (5)
a. Herpes simplex virus
b. Mycobacterium tuberculosis
c. Toxoplasma Gondii
d. Varicella zoster (shingles)
e. Cytomegalovirus (CMV)
Opportunistic infections in immunocompromised patients:
Common infections seen in HIV+ patients
a. Oral: (3)
b. Skin: (1)
c. Ocular: (3)
d. Pulmonary (numerous) (9)
e. Neurologic (2)
i. Candida albicans
ii. Oral Hairy Leukoplakia (EBV-related)
iii. HSV
i. Kaposi’s sarcoma (HHV8)
i. Cytomegalovirus (CMV)
ii. Varicella-zoster retinitis
iii. Toxoplasma gondii
i. Mycobacterium tuberculosis (also M. avium, M. kansasii)
ii. Streptococcus pneumoniae
iii. Staphylococcus aureus
iv. Haemophilus influenzae
v. Pneumocystis
vi. Cryptococcus neoformans
vii. Histoplasma capsulatum
viii. Coccidioides immitis
ix. CMV
i. Toxoplasma gondii
ii. CMV
A 37 year-old homosexual male comes to the emergency room complaining of fever and headache. Four years earlier, he tested positive for the human immunodeficiency virus (HIV), but his immune system was judged to be functioning well, and no therapy was prescribed. One year ago, he was admitted to a hospital with pneumonia-like symptoms, and was diagnosed with Pneumocystis carinii pneumonia. At this time, his T cell count was low (175/mm3). After successful therapy, he was started on zidovudine, lamuvidine and efavirenz for HIV and sulfamethoxazole/trimethoprim to prevent recurrence of Pneumocystis infection. He was in relatively good health until two weeks ago when intermittent, dull, generalized headache began. He was also confused and disoriented. One week ago, the headache became more severe andconstant. His fever was 38.1°C. Physical examination suggested the patient’s condition to be normal.
Computer tomography (CT) scan of the head shows two space-occupying lesions of 1.7 cm in diameter in the left parietal lobe and 1.0 cm in the posterior right frontal lobe. Both lesions show circumferential (“ring”) enhancement following injection of contrast medium. The CT scan is considered to be most consistent with a diagnosis of _. In addition, his serum is positive for IgG antibody to _. The patient is treated with sulfadiazine and pyramethamine, and responds favorably.
Cause: _
toxoplasmosis
Toxoplasma gondii
Toxoplasma encephalitis
Toxoplasma Gondii:
a. (Obligate / Facultative) (intracellular / extracellular) parasite
_ and _ are a source of infection
_ are natural hosts for T. gondii, and infection with the parasite can cause rats (or mice) to become _ to cats (and therefore _)—ensuring the parasite will be able to undergo the _ cycle in cats…the parasite modifies the brain and behavior of infected rodents…
b. : common latent infection in population of many countries. _ (acute infection during pregnancy) can lead to severe complications for fetus/newborn (chorioretinitis, CNS disease)
c. Reactivation of latent infection ( in brain) can occur in _ patients
d. Immune response to T. gondii is primarily _ mediated immunity characterized by _ and _ production by CD4 T cells and NK cells
e. _ live in macrophages but can be destroyed by immune responses (_ form in humans)
f. Latent (cyst) form in the _ can remain clinically dormant for _
a. Obligate
intracellular
Cat feces and uncooked meat
Rodents
attracted
eaten
sexual
b. Toxoplasma
Congenital toxoplasmosis
c. cysts
AIDS
d. cell
CD8 CTL and IFN-g
e. Tachyzoites
replicative
f. brain
lifetime of host
