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Host and Defense > Week 3 > Flashcards

Week 3 Flashcards

1
Q

Define bacteremia

A

Presence of bacteria in the blood

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2
Q

What is the difference between transient and continuous bacteremia?

A

Transient - clearance exceeds entry. Source is local Infection somewhere (skin, lungs, bone, etc.)

Continuous - Seeding exceeds clearance capacity. (Usually due to endovascular infections such as endocarditis. ) (can be caused by any bacterial species)

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3
Q

Define septicemia

A

(Sepsis syndrome)

Clearance mechanisms subverted

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4
Q

Name four examples of endovascular infections

A 
Infective endocarditis 
Infected thrombus (in the venous system, clotting involved)
Mycotic aneurysm (arterial wall infection (rare, but very dangerous))
Infections of intravascular devices such as catheters, pacemakers, arterial conduits, etc.
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5
Q

In blood culturing, blood must be removed ____. Why is this important? Then the blood sample is diluted into ____.

A

Aseptically. This is important because you dont want any of the skin flora bacteria getting in the sample. This will mess with your results.

Broth

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6
Q

Blood culturing is sensitive. What is the most important variable in culturing?

A

Important variable is volume

Side note: in regards to specificity, false positivity rate varies

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7
Q

True or false… in endocarditis, it doesn’t matter when you do blood culturing because the result will always be positive.

A

True

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8
Q

What are some things that predisposes a person for endocarditis?

A

Congenital heart disease (anatomical issues due to development)
Rheumatic heart disease (autoimmune disease)
Conditions leading to bacteremia such as dental, urological, gastrointestinal.
Intravenous drug abuse
Hospitalization

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9
Q

True or false… without antibiotics, the survival rate of endocarditis is 0%

A

True

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10
Q

Describe the pathogenesis of endocarditis

A

1) Turbulent blood flow within heart (abnormal flow)
2) endothelial cell activation
3) fibrin & platelet deposition
4) silent or clinical bacteremia seed sterile vegetations (bacteria sticks to platelet deposits)
5) bacteria grow within fibrin vegetation

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11
Q

Why is it that endocardium structures such as valves, chorda tendenaie, papillary muscle attachments, and atria are practically helpless at fighting infections?

A

These structures do not have any capillaries (thus receiving blood flow from diffusion), which are required for neutrophils to access the site of infection (margination). Thus the innate and acquired immune mechanisms are subverted.

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12
Q

True or false… bacteria imbedded within vegetations in the heart are easily eradicated by the immune system

A

False. These are nearly impossible to entirely eradicate

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13
Q

True or false… endocarditis is characterized by unrestricted microbial replication within vegetations leading to in-vivo bacterial colonies

A

True

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14
Q

What is the difference between major and minor bacteremia according to the Duke criteria?

A

Major - continuous bacteremia. Target lesion on valves or other heart structures

Minor - fever, predisposing heart condition, injection drug user, embolic phenomena, immunological phenomena.

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15
Q

People with endocarditis often form embolic lesions such as tender osler’s nodes and janeways lesions, roth spots. What are these embolic lesions?

A

Embolic lesions are due to clots/vegetations/colonies stuff that travels through the vasculature and gets stuck causing a lesion. Osler’s nodes = often found in palms, painful due to antibody-antigen complexes. Janeway lesions = found on the plantar surfaces of feet. Roth spot = lesion in fundus of stomach? Conjunctival petechiae - lesions in eyelids.

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16
Q

True or false.. every bacterial species has the potential to cause endocarditis

A

True

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17
Q

What are the three most common types of bacteria found to cause endocarditis?

A

Staphylococci (S. Aureus)
Streptococci (S. Mutans)
Enterococci (Eikienella corrodens)

Fungi - candida
Gram negative bacilli

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18
Q

If you find streptococcus mutans in the blood of a patient, there is a ____ chance that this patient already has endocarditis

A

93%

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19
Q

Endocarditis can result in…. (6 things)

A 
Congestive heart failure
Stroke
Infarcts
Glomerulonerphritis 
Mycotic aneurysms 
Abscesses 
 (Local = myocardium, distant = embolic seeding)
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20
Q

In order to prevent endocarditis it is important to give prophylactic antibiotics prior to treatment to patients who… (4 things)

A

Have prosthetic heart valves

Have had previous endocarditis

Have congenital heart diseases

Have had a heart transplant

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21
Q

Describe the treatment for endocarditis

A

IV therapy
Bactericidal regimen
Treatment can last from 2-8 weeks
Surgery

Must eliminate every single bacterium

Cures about 97% of cases

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22
Q

Define symbiosis

A

An close, long-term interaction between individuals of different species. Usually means mutualism (both species benefit) but may also refer to other interactions such as commensalism, inquilinism, and parasitism

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23
Q

What is the difference between commensalism and parasitism?

A

Commensalism - one benefits, the other is unaffected

Parasitism - one benefits, the other is harmed. These are organisms that gains its nourishment from and lives in or on another organism.

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24
Q

What is the difference between parasites and pathogens?

A

Pathogens are actually parasites

Pathogens: an agent that causes disease, especially a virus, bacterium, or fungus

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25
Q

What is the difference between obligatory parasite and facultative parasite?

A

Obligatory parasite: parasite that is unable to survive outside of its host.

Facultative parasite: parasite that is able to exist independent of its host. (However, i prefers to live with a host)

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26
Q

What is the difference between an endoparasite and an ectoparasite?

A

Endoparasite: parasite that is established inside the body

Ectoparasite: parasite that is established on the exterior surface of its host.

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27
Q

What is the difference between a definitive host and an intermediate host?

A

Definitive host: host in which the adult and/or sexual phase of a parasite occurs

Intermediate host: host in which the the larval and/or asexual phase of a parasite occurs

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28
Q

What is the difference between an accidental/incidental host and a reservoir host?

A

Accidental/incidental host: host other than the normal host that is harboring the parasite.

Reservoir host: host that harbors a parasite that is also parasitic for humans and from which humans may be infected. (Rodents were reservoir hosts for the bubonic plague)

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29
Q

True or false… parasites can go through more than one intermediate host

A

True

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30
Q

What is the difference between the infective stage and the diagnostic stage? (In regards to mode of transmission of parasites)

A

Infective stage: stage in the parasite life cycle that is capable of invading a definitive host

Diagnostic stage: stage in the parasitic life cycle that can be identified by examining appropriate specimens from the host.

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31
Q

Parasitic infections are often referred to as ____

A

Infestations

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32
Q

What are the five different types of protozoan parasites?

A

Amoebas, flagellates, ciliates, apicomplexans, sporozoans

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33
Q

What are the two types of helminths?

A

Platyhelminthes (flatworms)

Nematoda (roundworms, nematodes)

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34
Q

What are the organelles of locomotion and the method of replication for the following protozoa?

Amoebas
Ciliates
Flagellates 
Apicomplexans
Sporozoans
A

Amoebas: pseudopods, binary fission

Ciliates: cilia, binary fission

Flagellates: flagella, binary fission

Apicomplexans/sporozoans: flagella (or none), schizogony or sporogony

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35
Q

What are the two life stages in most parasitic amoebas and flagellates?

A

Trophozoites

Cysts

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36
Q

For each, trophozoites and cysts, describe where its likely to be found, its motility, feeding, sensitivity to environment, reproductive stage, infectousness, whether its found in diarrheal stools or formed stools

A

Trophozoites: found in host, motile, feeding, sensitive to environment, reproductive, non infectious, found in diarrheal stools

Cysts: found in environment, nonmotile, nonfeeding, resistant to environment, non-reproductive, infectious, found in formed stools

37
Q

True or false.. most amoebas are pathogenic

A

False. Most are nonpathogenic

38
Q

Trophozoites of amoebas move by ____

A

Pseudopodia

39
Q

When you looking at a slide through a microscope, you may identify intestinal amoebas by finding a ____ (a small object fairly constant size and location in each amoeba) and chromatin located ____. You may also find cytoplasmic inclusions such as a _____ which is a dark-stained bar. If you find _____ inside the cytoplasm of an amoeba, it is very likely to be entamoeba histolytica

A

Karyosome

Peripheral chromatin

Chromatid bar

RBCs

40
Q

Which amoeba is found to be pathogenic?

A

Entamoeba histolytica

41
Q

What two amoebas are likely to be pathogens?

A

Entamoeba moshkovskii

Entamoeba banglaeshi

42
Q

Name some amoebas that may show up with disease. These are “along for the ride”, they dont cause the disease, but appear when the disease arises. Entamoeba…

A 
Dispar
Hartmanni 
Coli 
Polecki
Gingivalis*
Buetschlii
43
Q

Describe the life cycle of entamoeba histolytica

A

Infective stage: cyst

Cysts are ingested, then cysts and trophozoites are passed in feces, repeat

44
Q

If you find RBCs in the cytoplasm of an amoeba, the amoeba is most likely ____

A

Entamoeba histolytica.

45
Q

True or false… in entamoeba histolytica, you are likely to find chromatoid bars in the cysts, not trophozoites

A

True

46
Q

Name some symptoms of entamoeba histolytica

A

Dysentery (bloody diarrhea) and ulcers in colon

Troph migrates to liver, brain, and lungs!!! So the amoeba may be coughed up in the sputum

47
Q

True or false… most people infected with entamoeba histolytica are asymptomatic

A

True. About 90%!

48
Q

Antigen detection of amoeba infections are especially useful for distinguishing between the nonpathogenic infections such as ___ and pathogenic ones such as ____

A

E. Dispar

E. Histolytica

Another way to tell these apart is that histolytica is likely to have RBC inclusions while dispar does not (occasionally bacteria)

E. Dispar is a commensal organism

49
Q

What amoeba can be part of the flora of the mouth but only is an opportunistic pathogen? No cyst stage is known for this amoeba.

A

Entamoeba gingivalis

Also note that RBCs are rarely found in cytoplasmic inclusions of this amoeba… another way to distinguish it from histolytica, because this may also appear in sputum

50
Q

Describe the following features of dientameoba fragilis… , type of protozoa, infective stage, cyst, disease symptoms

A

Amoeba

Infective stage: troph

Cyst: yes (recently confirmed)

Disease symptoms: intermittent diarrhea and abdominal pain

51
Q

The trophozoites of flagellates move by ____, they multiply by ___, and most are pathogenic or nonpathogenic?

A

Flagella

Binary fission

Nonpathogenic

52
Q

Some flagellates have axostyle. What does this mean?

A

Rodlike supporting structure in some flagellates that gives rigidity to the body

53
Q

The incubation time of giardiasis is ___. What are its symptoms?

A

1-14 days

Diarrhea
Cramping
Nausea and vomiting

54
Q

Giardia is transmitted through the ___ route. It is a diarrheal disorder that affects the intestines ____.

A

Fecal/oral

Directly

55
Q

What is the most common protozoan pathogen of humans in industrialized countries? How is it transmitted?

A

Trichomonas vaginalis

Transmitted sexually

Infects vagina or male urethra and prostate

56
Q

Describe the troph and cyst of trichomonas vaginalis

A

Trophozoites: pyriform. Five flagella four anterior, one posterior

No cysts

57
Q

Where is trichomonas tenax likely to be found? Describe its troph and cyst stage.

A

Opportunistic oral pathogen. Normally found in saliva.

Troph: pyriform

Cyst: none

58
Q

What is a common way in which leishmania is transmitted?

A

Bite of phlebotomine sand fly

59
Q

What are the three possible clinical syndromes of leishmaniasis?

A

Cutaneous
Visceral
Mucocutaneous

60
Q

What species of leishmania causes mucocutaneous leishmaniasis of the nose and mouth and is painful?

A

Leishmania braziliensis

61
Q

What is the only ciliate that causes GI problems in humans?

A

Balantidium coli

62
Q

What is the infective stage of balantidium coli? How is it transmitted?

A

Cyst

Through contaminated food and water

63
Q

What is the most common symptom of balantidiasis?

A

Most patients lack symptoms

Possible diarrhea

This organism can be invasive

64
Q

What is the infective stage of cryptosporidiosis? How is is spread?

A

Infective stage: thick walled (sporulated) oocyst

Transmitted through contaminated food and water and RECREATIONAL WATER* (pools, hot tubs, etc.)

65
Q

True or false… cryptosporidium parvum is resistant to chlorine and ozone treatment

A

True

66
Q

What is the infective stage of cyclospora cayetanesis? How is it transmitted?

A

Infective stage: sporulated oocyst

Dx stage: unsporulated oocyst

Transmission: contaminated produce and water (also resistant to chlorine*)

67
Q

In fresh samples of ____, the organisms autofluoresce

A

Cyclospora cayetanesis

68
Q

What are cestodes?

A

Tapeworms

69
Q

What is the infective stage of cestodes? What is the diagnostic stage? How are they transmitted?

A

Infective stage: cysticerus
Diagnostic stage: egg, gravid proglottid

Transmission: ingestion of raw or undercooked meat containing cysticerci

70
Q

Taeniid eggs may be mistaken for ____

A

Pollen

71
Q

What is the greatest concern of cysticercosis?

A

Cerebral cysticercosis - seizures, mental disturbances, focal neurological deficits

72
Q

What is the most common cause of all cestode infections?

A

Hymenolepis nana

73
Q

What are trematodes?

A

Flukes

74
Q

What are nematodes?

A

Roundworms

75
Q

Arthropoda have bilateral symmetry, have an exoskeleton composed of ____, and have segmented bodies called ___

A

Chitin

Tagmosis

76
Q

In order for Arthropoda to grow, they shed their cuticle by a process called ___

A

Ecdysis

77
Q

What is the difference between anoplura and mallophaga?

A

Anoplura - sucking lice

Mallophaga - chewing lice

78
Q

What is pediculus humanis?

A

Human head and body louse.

79
Q

What are diptera?

A

True flies

80
Q

What are siphonaptera?

A

Fleas

81
Q

What are ixodidae?

A

Hard ticks

82
Q

What are argasidae?

A

Soft ticks (mites)

83
Q

What is eosinophilia? What causes it?

A

Increase in number of eosinophils. Usually due to presence of helminths

84
Q

True or false… tapeworms, flukes, and round worms can be coughed up in sputum

A

True

85
Q

How can ectoparasites cause problems?

A

They cause problems indirectly by allergy or transmitting diseases

86
Q

Name the parasites of the mouth.

A

Entamoeba gingivalis
Leishmania braziliensis
Trichomonas tenax (opportunistic)

87
Q

True or false… blastocystis hominis may be a pathogen

A

True

88
Q

Name the three coccidia species

A

Ispora belli
Sarcocystis species
Cryptosporidium species

Host and Defense (17 decks)

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