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Flashcards in Respiratory Pathogens Deck (52):
1

Three respiratory bugs (focused in this packet)

Mycobacteria

Mycoplasma

Corynebacteria

2

Mycobacteria shape and growth

Acid Fast Rods

SLOW growth (from one pole only)

3

Mycobacterium cell wall contains...

Mycolic acids

arabinogalactan

PG

4

3 characteristics of mycolic acids

  1. acid fastness
  2. protect from lysozyme + complement
  3. anchored to PG directly or by arabinogalactan

5

What is cord factor?

Trehalose Dymycolate + something else

6

Mycobacterium product that stimulates cytokine production?

 

What cytokines?

Lipoarabinomannan (LAM)

TNF and IL-6 (which stimulate replication of HIV long terminal repeats)

7

Mycobacterium Tuberculosis major symptoms

fatigue, unexplained weight loss, hemoptysis

8

Clinical pathway for TB infection

  1. primary infection = exudative lesion
  2. either Heals, Necrotizes lung, or makes granuloma
  3. Granuloma is either encased or spreads via lymph and blood

9

What is miliary TB?

a widely-disseminated TB infection

Also hits lungs

10

1. Cells in center of granuloma include...

2. What eventually forms upon tissue death?

1. MQ, BC'sDC's

2. Caseum forms from necrotic tissue that is damaged by inflammatory response and lack of blood supply

11

How many new TB cases per year?

10 million

(results in 1.5 million deaths)

12

High TB risk populations? (5)

  1. Minorities, Immigrants
  2. HIV patients
  3. Homeless
  4. Young/old
  5. Travelers

13

TB is always spread....

person to person via respiratory droplets

14

Tb attaches to _______ to invade.

What 3 cellular consequences does this have

Alveolar MQ

  1. Prevents phagolysosome fusion
  2. cytotoxicity from cord factor
  3. Cytokine mediated inflammation

15

Long term TB latency establishes in...

granulomas and bone marrow cells

16

Detection of TB is dependent on...

presence of T memory cells

17

Two ways to detect TB? Explain them?

Mantoux test

QuantiFERON-Gold assay (IGRA): tests for release of IFN-g when peripheral lymphocytes are stimulated by TB antigen

(more IGN-gamma is made when effector Tmem cells are present)

18

TB control?

Culture takes too long (6-8 weeks) and acid fast sputum stain needs a massive infection to be able to detect.

 

PCR is best!  Use Tb-specific primers

--98% detection

--takes 90 minutes

19

Qualifications for latent TB? Treat or let it resolve?

IGRA+ or PPD+ without symptoms, and with normal Xray

 

ALWAYS treat (Isoniazid, Rifampin, or combination of both)

20

Treatment regimens for TB

Chemotherapy = long term with 4 drugs (INH, P, R, E)  =  (4HREZ)

DOTS important!! (observe them taking medicine) 

 

21

BCG vaccine is used where? What is a pertinent fact regarding its use?

Everywhere but here

It will cause PPD+

22

Treatment for XDR-TB

NO = Beta lactams or carbapenems

YES =

  • Meropenem+clavulanate
  • Linezolid (but adverse reaction... neuropathy)

Other:

  • Delaminid (inhibits MA synthesis)
  • Bedaquiline (inhibits ATP synthase)

23

M. leprae initial presentation

whitened, anaesthetized skin area

 

progresses to either Tuberculoid (paucibacillary) or Lepromatous (multibacillary)

24

tuberculoid leprosy Sx

macular lesions

(usually) unilateral nerve involvement (sometimes bilateral)

25

Lepromatous leprosy Sx

Progressive nodular lesions

bilateral nerve death >> bone resorption and loss of extremities

26

M. Leprae tranmission and reservoirs?

transmitted by long-term contact

 

Humans and armidillos

27

M. leprae pathogenesis

inflammatory reaction damages nerve endings

hyposensitivity = soft tissue damage

28

M. Leprae treatment

Dapsone (sulfone) and Rifampin  ...(6-9 months)

Double treatment reduces sulfone resistance

29

Other Mycobacteria?

M. avium

  • Most common nosocomial infctn in AIDS
  • disseminated bacteremia
  • Treat with clarithromycin and ethambutol for life

M. Kansasii

  • TB like symptoms, noncommunicable

30

Mycoplasma types?

Mycoplasma pneumoniae

Mycoplasma genitalium

Ureaplasma urealyticum

31

Mycoplasma organism

really, really smalll. 380 genes.

 

like really small.

32

Mycoplasma cell wall

No cell wall!

 

Only a membrane, which has sterols that it steals from host

33

Mycoplasma appearance on agar?

fried-egg appearance

34

Mycoplasma presentation

(Walking) Atypical PNA (20%)

Tracheobronchitis (70%)

insidious onset, mild fever, lasts about 4 weeks

 

35

Mycoplasma can trigger...

Autoimmune encephalomyelitis

(due to immune mimicry)

36

Difference in breath sounds between typical and atypical PNA

Typical = bronchial breathing

Atypical = Wheeze (musical, high pitched, fine crackle)

37

Mycoplasma is transmitted via

respiratory droplets

38

Mycoplasma is common among...

school kids

 

highest in winter

39

Mycoplasma major pathogenic factors?

Proline-rich adhesion protein = forms elongated tip to adhere to epithelial cells

Protein M covers Fab region of antibody to block it

Cytotoxic effects = H2O2, O2 radical, competition for nutrients

40

Mycoplasma treatment

Can treat with Tetracycline or Erythromycin (macrolides)

(Azith is more common for treating lung infections right now, but resistance may become a problem)

 

**often do NOT treat if mild

41

Other Mycoplasmas typically present as ____. What are the three we covered?

STD's

  1. M. genitalium (normal flora, NGU)
  2. M. hominis (salpingitis and post-partum)
  3. Ureaplasma urealyticum: Produces urease because it requires 10% urea for growth. Cause of nongonococcal urethritis in males (bladder stone)

42

Corynebacterium diptheriae shape / structure

(hint: what is weird about this organism's structure?)

  • Club shaped, pleomorphic
  • Gram +
  • Aerobic
    • *contains outer membrane with mycolic acid

43

Corynebacterium culturing medium? (related to cell metabolism)

It will show up as black colonies on tellurite blood agar

b/c it reduces potassium tellurite to tellurium metal

44

Corynebacterium clinical presentation

  • Throat infection
  • Fever
  • Swollen lymph nodes --> Bull neck
  • PSEUDOMEMBRANE

45

How are toxigenic strains of Corynebacterium ID'd?

Elek immunodiffusion test

  • filter paper with antitoxin placed at right angles to streaks of bacteria
  • toxin and antitoxin form a precipitate

46

Corynebacterium spread via...

aerosolized droplets

47

Corynebacterium pathogenicity

AB toxin from beta phage conversion

  • B binds to EGF-like receptor
  • Partially denatures toxin in vesicle, hydrolysis occurs
  • A binds to NAD--> ADP Ribosylates EF-2 transcription factor (STOPS protein synthesis)

48

How are Corynebacterium pathogenic factors controlled by the cell?

"tox" genes are controlled by the DtxR repressor

  • Iron is a co-repressor
  • The ToxAB operon gets shut off at iron concentrations above 10uM
  • (Iron is normally kept low in the body by lactoferrin/transferrin

49

Clinically, why is the Corynebacterium toxin bad?

It causes cardiac damage, often resulting in heart failure and death

50

Do infants have passive immunity to Corynebacterium?

Yes!

Lasts for about two months

51

Corynebacterium vaccine type/dosing

Formalin-treated toxoid vaccine (DTaP)

Booster given every 10 years

***important for travelers to areas of high prevalence

52

Post infection control of Corynebacterium?

Quarantine

equine anti-toxin

PEN / ERYTH  (despite intoxication, not infection... it's to keep the number of bacteria low)