Micro Flashcards

1
Q

what bug is this

A

Neisseria gonorrhea

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

How does the presentation and epidemiology of pneumonia from mycoplasma pneumoniae differ from that of legionella pneumophila?

A

In common, they both do not show up well or at all on Gram stain.

Mycoplasma pneumoniae infection causes tracheobronchitis or walking pneumonia. However, symptoms of infection are typically subacute and mild. The presence of high fever and confusion makes an alternate diagnosis far more likely.

Legionella pneumophila infection is typically marked by high fever and fatigue followed by significant gastrointestinal, pulmonary, and constitutional symptoms.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

T/F: B cell deficiencies result in recurrent Bacterial infections whereas deficient T cells result in recurrent viral and fungal infections

A

TRUE

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what is cholera toxin

A

Cholera toxin stimulates adenylate cyclase via activation of Gs → increased cyclic AMP → increased ion (mainly chloride) and water secretion into the intestinal lumen → profuse liquid stools

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what is shiga toxin

A

A toxin produced by Shigella spp., which inhibits the 60S subunit of ribosomes by cleavage of adenine in rRNA (ribosomal RNA). Causes enterocyte damage and bloody diarrhea. Similar to the Shiga-like toxin produced by EHEC (enterohemorrhagic E. coli)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what is an endotoxin

A

A lipopolysaccharide found in the outer cell membrane of several gram-negative bacteria. Consists of O antigen, a core polysaccharide, and lipid A. Released by living bacteria through membrane blebbing and upon bacterial cell death, inducing host release of IL-1, IL-6, and TNF-α, which cause fever and hypotension leading to septic shock. Can also trigger the coagulation cascade, leading to disseminated intravascular coagulation (DIC).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

pertussis toxin

A

pertussis toxin binds to and activates adenylate cyclase by permanently inhibiting Gi

impairs phagocytosis, allowing the bacteria to survive

Pertussis toxin is responsible for most of the systemic manifestations associated with whooping cough (e.g. hypoglycemia, lymphocytosis, modulation of host immune response).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

in what population does Group B strep mostly occur

A

babies (pneumonia, meningitis, sepsis) mn: B for Babies

it is otherwise a common bacteria of the vagina, so pregnant pts are screened at 35-37 weeks gestation to make sure they don’t have it.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

anthrax toxin

A

an exotoxin consisting of protective antigen,lethal factor,and edema factor

lethal factor mechanism: inactivation of protein kinase signals macrophages to release TNF-alpha –>

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

tetanus toxin vs botulinum toxin

A

both tetanus and botulinum toxins (both from clostridium spp) are proteases that cleave the SNARE proteins, a component of the N-ethylmaleimide-sensitive factor attachment protein receptor complex, —> impairs vesicular fusion –> no neurotransmitter released

Tetanospasmin spreads by retrograde axonal transport CNS and blocks release of GABA and glycine in spinal cord –> tetanic paralysis

botulinum toxin inibits ACh release at NMJ

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what toxin does C perfringens produce

A

α-toxin, which is a phospholipase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what’s the pathogen and what infections does it cause

A

Listeria monocytogenes

Amnionitis, septicemia, and spontaneous abortion in pregnant patients;granulomatosis infantiseptica;meningitis immunocompromised patients,neonates,and older adults;mild,self-limiting gastroenteritis in healthy individuals.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what’s the pathogen and what infections does it cause

A

Nocardia

pulmonary infections in immunecompromised (pulmonary nocardiosis), cutaneous infections, can spread to CNS causing cerebral abscess

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what’s the pathogen and what infections does it cause

A

actinomyces

oral facial abscesses (a/w cavities or oromaxillary trauma), and PID with IUD use

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what’s the pathogen and what infections does it cause

A

mycobacteria

causes TB

induces release of TNF-alpha and produces sulfatides (prevent phagolysosome fusion)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

young pt with fever, severe sore throat, lymphadenopathy, and purulent tonsillar exudates.

what’s the dx?

A

streptococcal pharyngitis

note the LACK of cough

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

M protein is found on the surface of what pathogen

A

Group A Streptococci such as S pyogenes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

diptheria toxin

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

what is the pathogen and what infection(s) does it cause

A

diphtheria (club shaped gram positive rods)

Diphtheria presents with pharyngitis, cervical adenopathy, low-grade fever, and a characteristic gray-white pseudomembrane. Cardiac involvement can be seen 1 to 2 weeks after the onset of symptoms and can result in potentially life-threatening myocarditis and cardiomyopathy

mn: “i’m gonna dip into the club”

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Immunosuppressed patient with ring-enhancing brain lesion and the attached histopath, what’s the dx

A

Toxoplasma gondii

Toxoplasma is an intracellular protozoan parasite in humans.

Approximately 70% of the population of the United States is seropositive, so reactivation of cysts held in latency by a normal immune response becomes commonplace as the immune response declines.

Cats act as the definitive host of the parasite and shed infectious forms in their feces.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Epstein-Barr virus (EBV). It is characterized by

A

a positive heterophile test (monospot), fever, pharyngitis, and lymphadenopathy.

Importantly, a monospot would be negative in a patient with CMV infectious mononucleosis. EBV serology can be assessed with tests for the viral capsid antigen (VCA),

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

which pathogens exhibit Retroviral infection of T cells what what dzs are assoc.

A

HIV and human T-cell leukemia-lymphoma virus (HTLV), which are associated with non-Hodgkin lymphoma and adult T-cell leukemia/lymphoma, respectively.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

which virus is most commonly implicated in myocarditis in an otherwise healthy pt

A

cocksackie B (mn: the heart (Cardio) is like a Sack (sack-)

this is also responsible for pericarditis which is even more so like a sack

24
Q

what’s the pathogen

A

branching septate hyphae at a narrow angle –> Aspergillus (fungi)

opportunistic fungal infection a/w immunocompromised individuals, those with chronic ganulomatous dz (neutrophil dysfunction)

25
Q

positive heterophile antibody test indicates what pathogen

A

EBV

26
Q

“eosinophilic intranuclear inclusion bodies and multinucleated giant cells visible on Tzanck smear of epithelial cells”. what type of infection does this describe

A

HSV type 1

27
Q

______________ is the only pathogenic fungus that has a polysaccharide capsule. The capsule appears red on mucicarmine stain and as a clear unstained zone with India ink

A

Cryptococcus neoformans is the only pathogenic fungus that has a polysaccharide capsule. The capsule appears red on mucicarmine stain and as a clear unstained zone with India ink

28
Q

__________________ is the most common etiologic agent in subacute bacterial endocarditis following dental work.

A

S viridans

29
Q

__________ is part of the normal flora of the colon, and bacteremia or endocarditis caused by it is associated with colonic cancer in ~25% of cases.

A

S gallolyticus (formerly S. Bovis)

30
Q

what’s the pathogen?

A

roundworm (ascaris lumbricoides)

31
Q

what are the cephalosporin resistant organisms (mn: LAME)

A

Listereria Monocytogenes

Atypicals (mycoplasma, Chlamydia) (b/c no cell wall)

MRSA

Enterococci

32
Q

what’s the pathogen

A

Coccidioides Immitis

mn: the shape of the particples inside are like a bunch of little Cs and there’s 3 Cs in Coccidiodes

33
Q

what’s the pathogen

A

aspergillus (branching at 45 degrees pathognomonic)

commonly causes pulmonary dz in immunocompromised pts

has only one form (mold) as pictured

34
Q

what’s the pathogen

A
35
Q

what’s the pathogen

A

blastomyces dermatitidis

“round yeast with broad-based budding. These yeasts have thick, doubly refractive walls.”

36
Q

what’s the pathogen

A

cryptococcus neoformans

“yeast with a thick capsule and clear halo on india ink”

a/w meningitis among immunocompromised

mn: thick capsule = deep within the crypt

37
Q

what’s the pathogen

A

CMV

“prominent intranuclear inclusions surrounded by a clear halo”

38
Q

what’s the pathogen

A

histoplasmosis capsulatum

“small oval yeast within macrophages”

n.b differentiated from coccidiodes (bottom photo) by the fact that they are NOT spheres

39
Q

what’s the pathogen

A

Rhizopus (mucormycosis)

typically cause rhino-orbito-cerebral mucormycosis but can cause lung disease in immunocompromised patients

40
Q

what’s the pathogen

A

This peripheral blood smear comes from a patient with malaria. This infection happens to be with Plasmodium vivax. At the arrow is a RBC with a malarial parasite in the shape of a ring. Three other RBC’s in this smear are also infected with a ring trophozoite.

41
Q

T or F: you don’t get postherpetic neuralgia with HSV

A

TRUE, only with VZV (ch/by painful vesicular rash in dermatomal pattern

42
Q

What’s the pathogen

A

acute phase of Trypanosoma cruzi from the triatomine bug (endemic in latin america) –> causes Chagas dz

Chagas disease is divided into 2 phases:

The acute phase (8-12 weeks after transmission) is characterized by circulating trypomastigotes that are detectable on blood microscopy. Most patients are asymptomatic, but a minority develop nonspecific symptoms (eg, fever, malaise, anorexia) and inflammation/swelling at the site of inoculation (eg, eye swelling following conjunctival inoculation).

The chronic phase begins when the immune system eliminates circulating parasitemia, leading to resolution of acute symptoms. Patients subsequently develop a prolonged asymptomatic phase (“indeterminate form”), whereby serology is positive for T cruzi, but there are no symptoms, signs, detectable parasitemia, or indications of end-organ damage. After 1-3 decades, a minority of those with asymptomatic chronic infection develop end-organ disease of the heart or gastrointestinal system.

Chronic Chagas cardiomyopathy is the most common complication of Chagas disease. It is thought to be caused by chronic, low-grade, parasite-mediated myocarditis, which leads to the progressive destruction of cardiac fibers and subsequent cardiac fibrosis. Common complications include biventricular heart failure, cardiac arrhythmias (particularly ventricular arrhythmias), and ventricular aneurysm with intracardiac thrombus (leads to thromboembolic disease/stroke).

43
Q

what is the MOA of Shiga toxin

A

Shiga-like toxins inhibit 28S on the 60S ribosome subunit and disrupt cellular protein synthesis. –> effacement of enterocyte microvilli and apoptosis of enterocytes

This is the type of ecoli in EHEC (bloody diarrhea)

44
Q

what is the pathogenicity of uropathogenic E. Coli

A

Uropathogenic E coli (UPEC) use a special kind of fimbriae called P pili to attach to the urinary tract and create a biofilm to evade immunologic recognition and eradication. In addition, they use hemolysin to invade tissues and move up the urinary tract to cause anything from cystitis to pyelonephritis as the bacteria advance.

45
Q

what is the mechanism of pathogenicity of the type of E. Coli that causes neonatal meningitis

A

The most common gram-negative bacteria to cause neonatal meningitis is E coli. Strains with the K1 capsule cause the majority of the infections, and this is due to their ability to bind to neuroreceptors that have higher affinities for the K1 capsule. This allows the E coli to penetrate the blood-brain barrier, resulting in colonization and infections such as meningitis.

They inhibit phagocytosis and complement mediated lysis

46
Q

what is the mechanism of pathogenicity of ETEC (travelers diarrhea

A

Enterotoxigenic E coli (ETEC) use fimbriae to attach to the brush border of the small intestines, causing what is commonly known as traveler’s diarrhea. Once attached, ETEC release two types of enterotoxins: heat labile (cAMP-inducing toxin) and heat-stable (cGMP-inducing toxin). Both alter the enzyme cascades in intestinal cells, resulting in increased cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP). This results in hypermotility of the small intestine and the increased release of water and electrolytes, leading to diarrhea (Figure 5). ETEC do not invade intestinal cells and cause noninflammatory diarrhea.

47
Q

oval, budding yeast with pseudohyphae and branching at right angles describes what pathogen

A

candida

vs mucor/rhizopus which also branch at right angles, but do not have budding and are stained with color.

48
Q

pt with pneumonia sx and this lung biopsy stain

what’s the pathogen

A

pneomocystis jirovecii causing causes Pneumocystis pneumonia

49
Q

which pathogens are a/w dental carries

A

strep mutans and strep mitis (viridans sp)

mn: d for dental and Dextrans (which facilitates binding to tooth enamel and formation of fibrin-plt deposits on heart valves

50
Q

what pathogens are a/w keratitis from contact lens use

A

Pseudomonas aeruginosa is the most common cause of bacterial keratitis in contact lens users (> 60% of cases)

but also, staph

51
Q

which pathogens produce IgA protease (virulence factor)

A

S. pneumoniae, H. influenzae, and Neisseria spp

52
Q

which pathogen is most a/w sepsis and circulatory collapse (e.g. DIC) in previoulsy healthy young individuals

A

N. Meningitidis (d/t lipo-oligosacharride in cell wall = virulence factor)

53
Q

which one is amebiasis

which one is giardia

A

top = Entamoeba histolytica (amebiasis) –> bloody diarrhea with incubation period of 1-4 weeks

bottom = giardia –> non-bloody diarrhea, with incubation period of 1-2 weeks

54
Q

bloody diarrhea in absence of fecal leukocytes is suggestive of what etiology

A

amebiasis (because these organisms destroy leukocytes)

55
Q

chief sx in infection with Entamoeba histolytica

A

Entamoeba histolytica is an amoeba that causes colitis characterized by trophozoites and flask-shaped ulcers on biopsy. It can occasionally (~1%) invade the colonic wall and disseminate through the blood to the liver, brain, or lungs. A single amebic liver abscess is the most common extraintestinal manifestation.