Micro 1 Flashcards

1
Q

Route of entry for S. aureus meningitis

A

direct inoculation of surgical procedure or postoperatively through the wound - common in neurosurgical pts

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2
Q

Facultatively intracellular, motile, gram-positive rod that is the 3rd most common cause of meningitis in neonates

A

Listeria monocytogenes

also causes meningitis in IC pts and elderly

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3
Q

What are the CSF findings in bacterial meningitis?

A
  • increased neutrophils
  • increased protein
  • decreased glucose
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4
Q

Lancet-shaped gram-positive cocci in pairs

A

Streptococcus pneumoniae

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5
Q

Leading cause of CAP, otitis media, and meningitis in adults

A

S. pneumo

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6
Q

What food poisoning is most commonly associated with mayonnaise-containing food like potato or macaroni salad?

A

S. aureus staphyloenterotoxemia containing highly heat-stable preformed enterotoxin

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7
Q

What are 4 strains of bacteria that result from exotoxin formed after ingestion of the contaminated food?

A
  • ETEC and V. cholera: watery diarrhea

- EHEC and shigella: bloody diarrhea

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8
Q

What are 5 bacteria that invade the gut mucosa?

A
  1. Salmonella spp
  2. Shigella
  3. Yersinia enterocolitica
  4. EIEC
  5. C. jejuni
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9
Q

What is the mode of transmission for staphylococcal food poisoning?

A

food handler innoculating food with S. aureus and allowing food to incubate at room temperature

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10
Q

Multinulcated giant cells with some intranuclear inclusions + a clinical Hx of vesiculoulcerative gingivitis/lesions of oral mucous membranes and cervical lymphadenopathy in children ages 1-3

A

HSV1: herpetic gingivostomatitis

may be VZV, but HSV-1 more likely

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11
Q

Reactivation of what virus produces interstitial pneumonitis, retinitis, hepatitis, colitis, and/or generalized disease?

A

CMV

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12
Q

What could a chronic, transforming latent EBV virus resultin?

A

B-cell lymphoma

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13
Q

What are two examples of slow viruses that are degenerative disorders of the CNS?

A

SSPE nd progressive multifocal leukoencephalopathy

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14
Q

Neutropenia associated with leukemias and lymphomas are associated with what monomorphic mold?

A

Invasive aspergillosis

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15
Q

What is the mode of transmission of invasive aspergillosis?

A

hematogenous spread - tissue infarcts in skin, paranasal sinuses, kidneys, endocardium, and brain

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16
Q

Oval budding yeast with pseudohyphae (elongated yeast cells)

A

Candida albicans

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17
Q

Oval budding yeast with a thick capsule and india ink stain of CSF revealing wide clear zone around nucleus

A

Cryptococcus neoformans

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18
Q

What leads to the autoimmune response of rheumatic fever?

A

molecular mimicry between bacterial antigens and self antigens

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19
Q

What are the early and late findings of rheumatic fever?

A

early: migratory arthritis, pancarditis, subQ nodules, erythema multiforme, and sydenham chorea
late: mitral stenosis with rare involvement of aortic valve

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20
Q

Prevention of rheumatic fever complications

A

prompt Tx of streptococcal pharyngitis with penicillin

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21
Q

Do all strains of S. pyogenes have the ability to result in PSGN?

A

No, only the nephritogenic strains

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22
Q

What is the recommended treatment for methicillin-resistant S. epidermidis?

A

Vancomycin combined with rifampin or gentamicin or both

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23
Q

What are the complications of S. epidermidis endocarditis after valve replacement if untreated?

A

intracardiac abscess formation, dehiscence of the prosthetic valve from the heart, and septic embolization

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24
Q

What are 3 B-lactamase resistant penicillins?

A

methicillin, oxacillin, and nafcillin

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25
Q

Why is the anaerobic environment within a can conducive to C. botulism?

A

It allows spore germination and organism growth

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26
Q

is the botulism toxin actively secreted by the bacteria?

A

NO!!!!!!!!!!
The botulinum toxin produced by the vegetative bacteria remains intracellular until autolysis releases the potent neurotoxin into the food

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27
Q

What are the clinical manifestations of the 3Ds associated with botulism?

A

diplopia, dysphagia, and dysphonia

12-46h after consumption

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28
Q

What are the Tx strategies for botulism?

A

antitoxin for circulating toxin and

supportive measures like intubation and mechanical ventilation for diaphragmatic paralysis

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29
Q

What kind of infection is B. fragilis found in?

A

intraabdominal abscess - often polymicrobial with B. fragilis and E. coli being the most prominent
-B. fragilis is an anaerobic, gram negative bacillus

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30
Q

What kind of S. pneumo vaccine is given to children <2yo?

A

7-valent conjugated vaccine which contains polysaccharide antigens that are protein-coupled in order to stimulate the T cell immune response

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31
Q

6 live, attenuated vaccines?

A

MMR, rotavirus, VZV, and Sabin polio vaccine

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32
Q

Recombinant surface protein vaccine?

A

HBV

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33
Q

4 killed bacteria vaccines?

A

anthrax, cholera, pertussis, and plague

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34
Q

4 killed viral vaccines?

A

HAV, influenza, rabies, and Salk polio

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35
Q

2 inactivated toxin vaccines?

A

diptheria and tetanus

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36
Q

unconjugated polysaccharide vaccine that does not stimulate a helper T response

A

pneumococcal vaccine

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37
Q

Pt with COPD presents with high fever with relative bradycardia, headache and confusion, and watery diarrhea. Labs show hyponatremia, gram stain with many neutrophils but few or no organisms. What is the Dx and Tx

A

Legionella - respiratory FQs or newer macrolides

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38
Q

San Joaquin Valley Fever

A

Coccidioidomycosis

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39
Q

Why is mycoplasma pneumoniae often accompanied with a mild anemia?

A

Mycoplasma can cause hemolysis d/t antigenic similarity between itself and cell membranes of RBCs. When the immune system ounts a response against M. pneumoniae antigens, it also destroys some RBCs. After the infection has been eliminated and the immune system is no longer activated (faded), anemia resolves.

40
Q

What are 4 notable intracellular organisms?

A

Salmonella, N. gonorrhoeae, Chlamydia (obligate), and Rickettsia (obligate)

41
Q

What is the Tx for obligate intracellular protozoan that commonly infects HIV pts and shows spherical lesions in brain on MRI?

A

Toxo - Pyrimethamine and Sulfadiazine

-TMP-SMX for prophylaxis

42
Q

How are the presentations different for oral candidiasis and oral hairy leukoplakia?

A

Oral thrush is found in denture wearers, diabetics, and IC pts. It can be scraped off.
Tocacco use can cause leukoplakia, a precancerous lesion that manifests as white patches that cannot be scraped off.

43
Q

What are 4 naturally competent bacteria that undergo direct uptake of naked DNA from the environment via transformation?

A
  • S. pneumo
  • H. flu
  • N. gonorrhoeae & meningitidis
44
Q

How do nonvirulent, non-capsule-forming strains of S. pneumo acquire genes that code for capsule?

A

transformation

45
Q

A 25yo female presents to clinic with lower abdominal pain and scant bloody vaginal discharge. She als has a fever, rebound ab tenderness, purulent endocervical discharge, and cerivcal motion and adnexal tenderness on bimanual exam. She has been sexually active with multiple partners without using condoms. She has orthostatic hypotension and has a positive pregnancy test. What is most likely Dx and causitive agent? What is she most at risk for?

A

PID - either N. gonorrhoeae or C. trachomatis

-She is at risk for ectopic pregnancy

46
Q

What is the most likely route of entry of Neisseria meningococci into the blood and what virulence factors does it use?

A

Meningococci have pili which mediate adherence and penetration of mucosal epithelium and pharyngeal colonization. IgA protease facilitates survival or organisms in mucosa by destroying IgA Abs.

47
Q

How do meningogoccal pili play a role in the route of entry into the body?

A

They are responsible for epithelial attachment to the nasopharynx.

48
Q

Cell receptor for CMV

A

cellular integrins

49
Q

Cell receptor for EBV

A

CR2 (CD21)

50
Q

Cell receptor for HIV

A

CD4 and CXCR4/CCR5

51
Q

Cell receptor for Rabies

A

nAChR

52
Q

Cell receptor for Rhinovirus

A

ICAM1 (CD54)

53
Q

Single-stranded RNA viruses enveloped by a bullet-shaped capsule studded by glycoprotein spikes that bind to nicotinic ACh receptors

A

Rabies

54
Q

The vaccine that provides protection against H. flu contains PRP capsular polysaccharide of H. flu type b as well as diptheria toxoid. The conjugated diptheria toxoid to the polysaccharide in this faction functions to:

A

increase immunogenicity - the additional protection form the protein-PRP polysaccharide conjugate vaccine results from T-cell dependent stimulation of B-lymphocytes to undergo class switching from IgM –> IgG

55
Q

What is the MOA of doxycycline, tetracycline, and minocycline?

A

antibiotics that inhibit the bacterial 30S ribosomal subunit

56
Q

What is the MOA of chloramphenicol?

A

It is an anti-ribosomal antibiotic that acts to inhibit the 50S bacterial ribosomal subunit

57
Q

What are the only classes of antibiotics that diminish the ability of gram positive and gram negative bacteria to survive in osmotic stress?

A

Penicillins, cephalosporins, and vancomycin - disrupts peptidoglycan cell wall

58
Q

How do picornaviridae replicate?

A

They produce a polyprotein product that is cleaved by a specific viral protease which converts their polycistronic mRNA into monocistronic mRNA

59
Q

Classic triad for congenital toxoplasmosis

A

hydrocephalus, intracranial calcifications, and chorioretinitis

60
Q

How is congenital toxoplasmosis transmitted?

A

Transplacentally (in utero) - the fetus is affected only if the mother is infected during the first 6 mo. of pregnancy

61
Q

What are the functions of the two toxins in C. diff?

A
  • Toxin A (enterotoxin): acts as a neutrophil chemoattractant leading to mucosal inflammation, loss of water into the gut lumen (producing diarrhea), and mucosal death
  • Toxin B (cytotoxin): causes actin depolymerization, loss of cellular cytoskeleton integrity, cell death, and mucosal necrosis
62
Q

How do the toxins of Shigella (Shiga toxin) and EHEC (Shiga-like toxin) cause bloody diarrhea?

A

They inhibit ribosomal protein synthesis

63
Q

What are the main functions of Group A strep M Protein?

A

It inhibits phagocytosis and complement activation, mediates bacterial adherence, and is the target of type-specific humoral immunity to S. pyogenes

64
Q

Walking pneumonia with CXR that looks much worse than clinical presentation and organism requires cholesterol to grow

A

Mycoplasma - cell membrane is composed of single cholesterol-rich phospholipid bilayer

65
Q

What are the 5 important steps to prevent central venous catheter infections?

A
  • proper hand washing
  • full barrier precautions during insertion of central line
  • chlorhexidine for skin disinfection
  • avoidance of femoral insertion site
  • removal of catheter(s) when no longer needed
66
Q

MOA of alcohol (isopropanol, ethanol) disinfectant

A

disruption of cell membranes and denaturation of proteins

67
Q

MOA of Chlorhexidine disinfectant

A

disruption of cell membranes and coagulation of cytoplasm

-antiseptic of choice for many surgical and percutaneous procedures

68
Q

MOA of hydrogen peroxide disinfectant

A

produces destructive free radicals that oxidize cellular components; sporicidal
-excellent for fomites

69
Q

MOA of iodine disinfectant

A

halogenation of proteins and nucleic acids; sporicidal

70
Q

What infection is strongly associated with AIDS-related primary CNS lymphoma

A

latent EBV infection composed of B-lymphocytes

71
Q

How is listeria transmitted to cause neonatal meningitis?

A

transplacentally or via vaginal contact

72
Q

gram positive rod with V or L formations with tumbling motility

A

listeria monocytogenes

73
Q

What is the most common cause of acute bacterial arthritis in sexually active young adults?

A

N. gonorrHOeae

dem bitches be hos

74
Q

What is the most common cause of septic arthritis in children and non-sexually active adults?

A

S. aureus

75
Q

Broad-based budding encapsulated yeast endemic to Great Lakes, OH, and MS River valey present in soil and rotten organic matter

A

Blastomyces

76
Q

What is the best method to Dx C. diff colitis?

A

PCR detection of toxin A and B genes in the stool

77
Q

What things besides syphilis does VDRL test positive for?

A
V: viruses (mono and hepatitis)
D: drugs
R: rheumatic fever
L: lupus and leprosy
-requires mixture of cardiolipin, lecithin, and cholesterol
78
Q

What are the 3 components of LPS and which one is responsible for the toxic properties of LPS that leads to gram-negative septic shock?

A

O antigen, core polysaccharide, and Lipid A

*Lipid A is responsible

79
Q

How does Lipid A induce shcock?

A

It activates macrophages and granuloctes and production of endogenous pyrogens and inflammatory mediators like IL-1, TNF-a, and IFN

80
Q

What E. coli virulence factor is important for neonatal meningitis?

A

K-1 capsule antigen

81
Q

What are clue cells?

A

vaginal squamous epithelial cells covered in small dark particles (G. vaginalis) in BV

82
Q

What is the Tx for BV?

A

oral metronidazole

83
Q

How does S. typhi invade the gut mucosa?

A

S. typhi penetrate the gut mucosa via transporters on enterocytes and via phagocytosis by M cells in Peyer patches

84
Q

What are the clinical manifestations of S. typhi?

A

mild abdominal cramping with low grade fever and diarrhea OR constipation initially; subsequently pt can develop rose spots on abdomen, HSmegaly and recolonization of the gut leading to hemorrhagic diarrhea and sepsis with bowel perforation

85
Q

How does TSST-1 activate a widespread T cell response?

A

It interacts with the MHC molecules on APCs and the variable region of the T lymphocyte receptor which leads to release of IL-2 from T cells and IL-1 NAD tnf FROM MACROPAHGES

86
Q

How do the causative factors of PSGN and Rheumatic Fever differ?

A

PSGN can be caused by GAS impetigo or streptococcal pharyngitis, whereas rheumatic fever is only associated with streptococcal pharyngitis

87
Q

4 autoimmune disorders associated with HLA-B27

A
PAIR
P: psoriatic arthritis
A: ankylosing spondylitis
I: IBD
R: reactive arthritis
88
Q

alpha-hemolytic, optochin-resistant

A

Viridans strep

89
Q

beta-hemolytic, bacitracin-resistant

A

Strep agalactiae

90
Q

gamma-hemolytic, growth in bile AND 6.5% NaCl

A

Enterococci

91
Q

gamma -hemolytic, growth in bile but NOT 6.5% NaCl

A

Nonenterococci S. bovis

92
Q

What is the classic triad for congenital rubella?

A
congenital cataracts (white pupils), sensory-neural deafness, and PDA
-can also present with microcephaly and MR
93
Q

Why is a live, attenuated vaccine frequently more effective than a viral component or killed vaccine?

A

Viral component/killed vaccine induce only humoral immunity, whereas live-attenuated vaccines induce both humoral and CMI

94
Q

What is leukocyte IFN-a currently approved to treat? How does it work?

A

HBV, HCV, hairy cell leukemia, condyloma acuminatum, and KS

-it inhibits various stages of viral RNA and DNA synthesis

95
Q

What kind of viruses can be destroyed by ether?

A

enveloped viruces (nonenveloped - resistant to ether)