Mycobacteria/ Mollicutes

Question 1

mycobacteria- o2, motile?, spore?, intra/extracellular, shape

Answer 1

o2- obligate aerobes
motile- non motile
spore- no
Faculative intracellular (in and out)
Rod shaped

Question 2

Gram of mycobacteria and what stain is it best seen in

Answer 2

Neither G+ or - it is acid fast (thick layer of mycolic acids)

-Ziehl-Meelsen stain (will be bright red)

Question 3

steps of ziehl meelsan stain

Answer 3

1. application of primary stain
2. application of heat
3. application of acid (releases stain from non acid ones
4. counter stain applied

Question 4

3 myobacterium spp

Answer 4

1. Mycobacterium tuberculosis
2. Mycobacterium lapraee
3. Mac complex (m avium/m intracellulare)

Question 5

Where is the transmission of tuberculosis

Answer 5

Inhalation of aerosolized infectious particles or respiratory droplets generated by coughing/sneezing

Question 6

What are the risk factors of Tb infection

Answer 6

HIV
Close contact
immune supression
overcrowding
malnutrition

Question 7

What is the general pathology of TB and how does it evade immune

Answer 7

tb multiply in alvelolar spaces/withing macrophages

• survive in macrophage by producing urease
• after multiplying they egress from cell killing it in process (inflammation/necrosis)

Question 8

How does the immune system contain TB

Answer 8

triggering Th1 cells and forming granulomas around infected tissues (infected macrophage surrounded by t cells)

Question 9

What is active vs latent tb

Answer 9

active TB occurs when protectibe mechanisms disapear allowing contained bacteria to spread/overgrow

Latent TB not known to cause symtoms

Question 10

Pulmonary tb symptoms

Answer 10

lung tissue progressivly famaged causing systemic symptoms like fever, productive cough, chest pain, weight loss, night sweats

Question 11

Extrapulmonary tb symptoms + % of time

Answer 11

20% of time

• CNS- menengitis
• lymph nodes- scrofula
• miliary tb
• bones, liverm kidney, gi

Question 12

What is potts disease of the spine

Answer 12

Tuberculous spondylitis

-rare complication of tb that spreads to spine (infect intervetebral disk/vert)

Question 13

How to diagnose TB

Answer 13

s/s present for 2 w
-positive culture, acid fast bacilli noted
chest xrays (opacities in upper lobes)

Question 14

Does TB have a vaccine

Answer 14

preventable (does not prevent infection but usually prevents serious)
-live attenuated

Question 15

What are the antibitics required for tb tx (4)

Answer 15

1. Isoniazid (inhitis mycoloc acid synthesis)
2. Rifampin (inhibits bac RNA polymerase)
3. Pyrazinamide
4. Ethambutol

Question 16

myobacterium laprae- what does it cause, intra/extra cellular, o2, shape

Answer 16

Leprosy

• Obligate intracellular
• Aerobic
• bacilli

Question 17

How is leprosy transmitted + mc age

Answer 17

Spread thru cough or contact with respiratory secretions
-soom zoonic transmission as well

mc- 10-19 years of age, 30+)

Question 18

pathogenisis of leprosy (2 things it infects +symptoms)

Answer 18

Bacilli infect and replicate in skin cells leading to characteristic lesions of hyperpigmentation souroneded by red border

-infect schwann cells leading to demyleination in peripheral nerves (Sensory deficits)

Question 19

What are the 2 forms of leprosy and which is more severe

Answer 19

1. Tuberculoid- milder, small # of skin lesions, well formed granulomas (th1)
2. Lepromatous- severe, more skin lesions, poorly formed granulomas (th2)

Question 20

what is the tx of leprosy

Answer 20

multidrug therapy- 6-24 m regimen of 2-3 antibiotics

Question 21

How is the MAC complex transmited

Answer 21

due to inhalation or ingestion

Question 22

What are the 2 major diseases in humans caused by MAC

Answer 22

1. Pulmonary disease- presents like pulmonary tb

2. Disseminated disease- Common in GI, liver, lymphoid tissues

Question 23

What are the 2 spp related to mollicutes

Answer 23

1. Mycoplasma pneumoniae

2. Gentital mollicute

Question 24

What are mollicutes resistent to

Answer 24

b lactams (as they have no cell wall)

Question 25

what are the virulence factors of mycoplasma pneumoniae

Answer 25

Makes cytotoxin that damages respiratory epithelium and cillary activity

Question 26

Who does myocplama pneumoniae usually affect and symptoms

Answer 26

children/adolescents (upper respiratory tract infection)

Atypical pneumonia- gradual onset of low fever, malaise, headache, cough
-skin infections (small, target shaped)

Question 27

is myocplasma pneumoniae vaccine preventable

Answer 27

not vaccine preventable

Question 28

How is genital mollicute infections transmitted and what does it cause

Answer 28

Exposure is comon, possibly thru sex

Urethritis- discharge, painful burning urination