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CPR Part II > Microbiology > Flashcards

Microbiology Flashcards

1
Q

Common URIs

nasopharynx =

A

viruses! rhinovirus

coronavirus, coxsackie A/B, influenza C

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2
Q

Common URIs

oropharynx =

A

streptococcus pyogenes (“GpA Strep”)
corynebacterium diptheria
EBV, adenovirus, enterovirus

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3
Q

Common URIs

middle ear/parasinuses =

A

streptococcus pneumonia
haemophilus influenzae (non-encapsulated)
(think how pneumonia can cause otitis media)
also - moraxella catarrhalis, GpA strep

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4
Q

Common URIs

epiglottis =

A

haemophilus influenzae type b

(think how pneumonia can cause epiglottitis

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5
Q

Streptococcus Pyogenes/GpA Strep

ID/Diagnosis

A

Gm+ cocci in chains
catalase negative (=streptococci, not staphylococcus)
beta-hemolytic (clear hemolysis)
bacitracin sensitive (= streptococcus pyogenes)
ASO+ (anti-streptolysin O Ab is present)
confirm via commercial test w/ latex beads
*even if rapid test (RADT) is –ve, perform a GAS culture

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6
Q

Streptococcus Pyogenes/GpA Strep

Clinical Presentation

A

pharyngitis = inflammation of oropharynx, petechiae on soft palate; possibly nausea, vomiting, abdominal pain
*Suppurative
pharyngitis (rarely w/ scarlet fever)
pyoderma - impetigo, erysipelas, cellulitis
necrotizing fasciitis (toxin mediated)
streptococcal toxic shock syndrome (toxin mediated)
*Nonsuppurative
rheumatic fever (M proteins, molecular mimicry)
glomerulonephritis (immune mediated)

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7
Q

Streptococcus Pyogenes/GpA Strep

Virulence

A

M Protein - anti-phagocytic, molecular mimicry
Streptokinase (ASO+) - converts plasminogen to plasmin
Hyaluronidase - breaks down connective tissue
DNase - digests DNA

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8
Q

Streptococcus Pyogenes/GpA Strep

Treatment

A

Penicillin G

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9
Q

Haemophilus Influenzae

ID/Diagnosis

A

Gm– coccobacilli (= haemophilus)
oxidase +
chocolate agar + hemin (X factor) + NAD+ (V factor)
5-10% CO2
*slide agglutination test - determine type a-f

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10
Q

Haemophilus Influenzae

Clinical Presentation

A 
Encapsulated (type b)
bacterial meningitis (most common cause)
epiglottitis
pneumonia - kids, adults w/ COPD etc
Unencapsulated (normal flora)
otitis media + sinusitis, conjunctivitis
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11
Q

Haemophilus Influenzae

Virulence

A

6 capsular types, type a-f
type b capsule = polyribose-ribitol-phosphate (PRP, Hib)
PRP is anti-phagocytic
also - adhesive pili, factor that dysregulated ciliary beating, protease that degrade IgA

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12
Q

Haemophilus Influenzae

Treatment

A

vaccination = Hib polysaccharide protein coupled to diptheria toxoid
tx - 3rd generation cephalosporin or ampicillin

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13
Q

Corynebacterium Diphtheriae

ID/Diagnosis

A

Gm+ bacilli - “Chinese letters”
catalase +, non-motile, non-spore forming
black colonies on potassium tellurite
*diphtheroids are normal flora; differentiate pathogenic corynebacterium via PCR

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14
Q

Corynebacterium Diphtheriae

Clinical Presentation

A

any mucus membrane
pseudomembrane + airway obstruction
myocarditis, polyneuritis (nerve palsy)

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15
Q

Corynebacterium Diphtheriae

Virulence

A

diphtheria toxin, toxin AB
prevents protein synthesis in all cells
ADP-ribosylates and inactivates EF-2

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16
Q

Corynebacterium Diphtheriae

Treatment

A

antibiotics, antitoxin (horse, potential for serum sickness)

vaccination - DTaP, contains inactivated toxoid AB

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17
Q

Rhinovirus - Transmission

A

respiratory droplets
direct contact
starts with R, transmitted via Respiratory droplets

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18
Q

RSV - Transmission

A

respiratory droplets
direct contact
“respiratory” SV, transmitted via “respiratory” droplets

19
Q

Adenovirus - Transmission

A 
respiratory droplets
direct contact
\+ fecal-oral
\+ contaminated water
(ADenovirus has ADditional methods of transmission)
20
Q

EBV - Transmission

A

saliva, the “kissing disease”

21
Q

Rhinovirus - Target Cells

A

respiratory epithelial cells of nose (lower temp, 88-90F)

22
Q

RSV - Target Cells

A

epithelial cells of URT

23
Q

Adenovirus - Target Cells

A

mucoepithelial cells, “adeno”id cells

24
Q

EBV - Target Cells

A

epithelial and “B” cells

25
Q

Rhinovirus - Clinical Presentation

A

Common Cold - incubation (2-4 days), self-limiting

rarely, bronchopneumonia (kids) or chronic lung injury (COPD, asthmatics, immunocompromised)

26
Q

RSV - Clinical Presentation

A

URT, Croup, Bronchiolitis
Croup = cold + tachypnea, wheezing, cyanosis
self-limiting (7-10 days)
*immunity is not long-lived, can have repeated infections

27
Q

Adenovirus - Clinical Presentation

A

Pharyngitis, Acute Respiratory Disease (*military recruits)
self-limiting (7-10 days)
Conjuntivitis, Pneumonia

28
Q

EBV - Clinical Presentation

A

Pharyngitis, Mononucleosis- self-limiting (2-3 weeks)

swelling, redness and white patches on tonsils; swelling of lymph nodes (Cervical Lymphadenopathy)

29
Q

Rhinovirus, RSV, Adenovirus, EBV

Diagnosis and Treatment

A

Ddx - symptoms, viral culture, PCR, ELISA, DFA (direct fluorescent antibody), serology. EBV can be detected via atypical lymphocytes (CD8 CTL) and agglutination tests for heterophile antibody.

*Vaccines
rhinovirus - none due to >100 serotypes
RSV - none, limited success treatment with ribavirin or RespiGam (passive immunity)
adenovirus - none, live tablet now available in military
EBV - none

30
Q

Rhinovirus, RSV, Adenovirus, EBV

Structure

A

Rhinovirus: +ssRNA, icosahedral, nonenveloped
RSV: –ssRNA, helical, enveloped
Adenovirus: dsDNA, icosahedral, nonenveloped
EBV: dsDNA, icosahedral, enveloped
RSV has F (fusion) and G (attachment) proteins.

*RNA viruses start w/ R; RSV is only helical virus; viruses with 3 letter abbreviation are enveloped

31
Q

Rhinovirus, RSV, Adenovirus, EBV

Replication and Cell Cycle

A

RNA viruses (rhinovirus and RSV) replicate in cytoplasm; DNA viruses (adenovirus, EBV) replicate in nucleus.

Rhinovirus - released via cytolysis.
RSV - released via exocytosis, forms syncytium.
Adenovirus - lytic (mucoepithelial cells) or latent (adenoids).
EBV - released via exocytosis or lysis.

32
Q

Influenza Viruses

Orthomyxoviruses - Characteristics

A

–RNA, 8 segments, enveloped
HA (haemagglutinin) and NA (neuraminidase) spikes
type A - antigenic shift and drift, most disease
type B - antigenic drift
type C - stable, cause of cold-like symptoms

33
Q

Influenza Viruses - Replication

A
  1. HA binds sialic acid moiety, enters cell.
  2. Acidic pH (via M2 ion channel) facilitates particle disassembly and envelop fusion.
  3. Replication and protein synthesis.
  4. NA cleaves HA-sialic acid bond, facilitation virus release.
34
Q

Influenza Viruses - Pathogenesis

A
  1. Short incubation (1-4 days).
  2. Replicates in respiratory epithelium; no viremia.
  3. Damage to respiratory epithelium renders susceptible to secondary infections (pneumonias).
  4. Interferons and cytokines produce symptoms of disease.
  5. Immunity via IgA in respiratory tract (can still infect others).
35
Q

Influenza Viruses - Clinical Presentation

A

Primary Infection - HIGH fever (IL-1), etc.
Complications - secondary bacterial pneumonia, viral pneumonia (severe disease -> ARDS), myositis, cardiac involvement, neurologic symtoms.

36
Q

Influenza Viruses - Vaccines

A

QIV - Quadrivalent Inactivated Vaccine
2 type A, 2 type B
intramuscular injection
healthy persons > 6 mo.

LAIV - Live Attenuated Influenza Vaccine
2 type A, 2 type B
nasal spray (Flumist)
healthy persons btw 2 and 49 years

H1N1 Monovalent Vaccine (Swine Flu)
pregnant women, caregivers of children < 6mo., kids 6 mo.-24 years, persons 24-64 with health conditions that put them at risk

37
Q

Influenza Viruses - Treatments

A

NA Inhibitors = OseltaMIVIR (Tamiflu) and ZanaMIVIR (Relenza) - inhibits viral shedding, type A and B

M2 Inhibitors = AMANTIDINE, RiMANTIDINE - give early, blocks M2 channel, increases pH in endosome, prevents viral disassembly; type A ONLY

38
Q

Mycobacterium TB - Epidemiology

A

Exposed? 30% are infected.
Infected? 5% develop disease w/in 2 years.
Latent infection? 5% develop disease w/in lifetime.
Active infection? 10-20% develop non-infectious extra-pulmonary disseminated disease.

39
Q

Mycobacterium TB - Clinical Presentation

A

fever/night sweats, cough/hemoptysis, weight loss, fatigue, chest pain

40
Q

Mycobacterium TB - Risk Groups

A

Exposure - close contacts, foreigners, healthcare workers, low socio-economic class

Development of Dz - HIV/AID, IV drug users, immunocompromised, other medical conditions (type 1 diabetes, renal impairment, cancer, etc)

41
Q

Mycobacterium TB - Pathogenesis

A

Primary TB - caseating granulomas, Ghon Complex = primary lesion (TB w/in macrophage) + infected adjoining lymph node -> calcify.

Reactivation TB - rupture of granuloma, cavitation on CXR, usually in apices of lung.

Miliary TB - small lesions in multiple organs.

also…lymphadenitis (associated with M. bovis and milk), meningitis, Pott’s disease (vertebrae, posts m.)

42
Q

Mycobacterium TB - Diagnosis

A

PPD Test (purified protein derivative)

Interferon Gamma Release Assays - more sensitive, can be used in persons vaccinated with M. bovis-derived vaccine

CXR - latent (Ghon) v. active (cavitary lesion)
Culture for acid-fast bacilli! Gold-Standard

43
Q

Mycobacterium TB - Treatment

A

Latent - 9 mo. isoniazid

Active - 9 mo. RIPE = rifampin, isoniazid, pyrazinamide, ethambutol; consider DOT (direct observed therapy)

44
Q

Mycobacterium TB - Vaccine

A

BCG Vaccine - live attenuated M bovis

not used in US due to adverse reactions, waning of immunity @ 10 years, false + PPD

CPR Part II (5 decks)

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