Micro-Mycobacterium & Other G- Rods

Front 1

What are the general characteristics of the genus Mycobacterium?

Back 1

Related to G+ but don't Gstain well
Acid Fast
Produce Niacin & heat-stable catalse
High GC content DNA
Thicy waxy cell wall, with mycolic acids

Front 2

What are the general characteristics of Mycobacterium tuberculosis?

Back 2

Cord factor in cell wall helps evade immune syst & form granulomas
Slow grower, fastidious obligate aerobe

Front 3

What are non-human resevoirs for mycobacterium?

Back 3

Many live in soil or water & aren't human pathogens.
M. bovis - ruminants
M. microti - voles
M. leprae - armadillos
M. tb - NONE

Front 4

Which bacteria are responsible for Human TB? What is the 4th bacteria in the "TB complex" that doesn't cause human TB?

Back 4

M. tb
M. bovis
M. africanum

Last one in complex: M. microti - not human TB agent

Front 5

TB: How much of the world is infected? How many die per year? New Cases per year?
Which regions are most cases found?

Back 5

1/3 world infected
Kills 2 million/year
Most cases in south-east Asia or sub-Saharan Africa

Front 6

What vaccine is used for TB? Derived from what? Efficacy?

Back 6

BCG (Gacille Calmette Guerin) vaccine from M.bovis. Different strains used for vaccine production in different countries, so efficacy widely varies (from 0-90%). Most not very effective. Not used in US

Front 7

What's Miliary TB?

Back 7

"Millet seeds" of tb infection spread throughout the body

Front 8

How is TB transmitted?

Back 8

By inhaling aerosolized microdroplets of bacteria expelled by a person with ACTIVE TB.
If the droplets are large, they won't reach the alveoli, thus will not cause infection.
Fomites do not transmit TB infection.

Front 9

5 stages to TB infection:
What happens in the first 3 stages?

Back 9

1) inhaled droplet with bacilli reaches alveoli
2) Bacilli grow or are killed (halting infection
3)Granuloma forms with macrophages & Tcells. May completely contain infection & calcify with age

Front 10

5 stages to TB infection:
What happens in the last 2 stages?

Back 10

4) If granuloma inhibit or kill bacilli, infection halted. Otherwise a caseous necrotic center devolps due to weak cell med immunity & bacilli multiply
5)Granuloma degenerates, liquifies & liquid leaks out (leaving cavity "shell"). Active, contagious TB infection

Front 11

What percentage of People with close-contact exposure to TB will be infected? Of those, what percent will have Active TB?

Back 11

Only 30% infected
Of those infected, only 40% will immediately have Active TB. The other 60% will be latent infection until TB is either reactivated (2-23% per lifetime) or HIV infection (then additional 5-10% chance/year)

Front 12

Are children who are infected with TB contagious? Are adults?

Back 12

CDC doesn't consider kids infectious due to lack of granuloma formation (different cell mediated immunity).
Adults are infectious ONLY if TB is active (cavities in lungs are leaking liquid with bacilli)

Front 13

What are the risk factors for Active TB disease?

Back 13

-Immunosuppresion
-Senescence (old age)
-Poor nutrition
-Chronic medical conditions (diabetes, CA, renal failure)

Front 14

How is TB infection tested for?
(Skin Test)

Back 14

PPD (purified protien derivative) skil test looks for cell-mediated immune rxn by checking size changes of the "area on induration" (site where ppd injection subcutaneously) after 72 hrs. HIV+ pts may not have immune response even with TB infection

Front 15

How is TB infection tested for?
(blood test)

Back 15

QuantiFERON-TB test uses whole blood to measure levels of INF-gamma (produced in response to TB antigens) Immediate results, no

Front 16

How is TB infection tested for?
(Sputum test)

Back 16

Sputum digested to isolate bacilli
Acid fast or auramine-rhodamine stain
Grown usually on Lowenstein-Jensen media with malachite green indicator
Usually active disease will be smear+ but neg in 10-15%

Front 17

How is TB infection tested for?
(X-ray)

Back 17

Chest X-ray will show abnormalities in almost all active cases
CT more sensitive

Front 18

Problem with PPD test?

Back 18

False + if vaccinated with BCG or exposed to non-TB mycobacteria
False neg in 10-15% of active cases, often due to low cell mediated immune response to infection
Biased interpretation/human error
"reading" results - what is considered + changes with patient risk factors (Pt may not reveal all)
Unchanged since 1941!

Front 19

How is TB Controled?

Back 19

Isolation wards with HEPA filters & UV lights for active TB
6-9 months of antibiotics for active disease - many areas use Directly Observed Therapy to ensure compliance

Front 20

Now after all those flashcards: what are the 3 key points to remember about TB?

Back 20

1) Infections doesn't equal disease
2) Latent infection can last a lifetime without becoming active
3) BCG vaccine isn't effective

Front 21

What bacteria causes Leprosy? Characteristics of the bacteria?

Back 21

Mycobacterium leprae -acid-fact bacilli, obligate parasite (can't be cultured)also found in Armadillos
Grows at lower that 37 C, so affects extremities that at cooler that body temp

Front 22

Describe Tuberculoid Leprosy

Back 22

-Granulomas formed by strong cell meciated immunity (like in TB). If near nerve, can damage dermal & autonomic nerve fibers
-Incubation 2-5 yrs
-Not associated with skin or upper respitory tract symptoms

Front 23

Describe Lepromatous/multibacillary Leprosy

Back 23

-Poor or no cell mediated immunity so any granulomas formed are ineffective
-Bacilli muliply in cool ares of body & attackis skin, peripheral nerves & upper resp. tract
-Incubation 8-12 yrs

Front 24

Describe Mycobacterium ulcerans

Back 24

-Acid fast bacilli that causes progressive ulceration of the skin with dermal nerve damage - "buruli ulcer"
Endemic to parts of Afric & Australia in water sourves

Front 25

How are MOTTs (Mycobaterium Other Than Tuberculosis) classified? Name 3 species

Back 25

The Runyon classification system, by speed of growth - I-IV
(we don't have to know details of the classes)
M. avium, M. kansasii, and M. marinum (model for TB study, causes swimmer's nodule)

Front 26

What is Lady Windemere syndrome?
What other populations contract the same infection?

Back 26

Infection of M. avium in "little old ladies" causing pulmonary disease, adenitis and disseminated disease.

Also seen in immunocompromised pts, CA, lung disease/COPD & chronic bronchitis

Front 27

Vaccine for Leprosy?

Back 27

Some countries use BCG but not very effective, not used in US
Those at very high rish (long-term close contact exposure) may use prophyactic antibiotics

Front 28

Describe the order Actinomycetales. Name 5 genuses within that Actinomycetales.

Back 28

Most abundant bacteria in soil, many with mold-like appearance, break down organic matter

Nocardia, Streptomyces & Actinomyces were all mistaken as fungi originally
Also in this order: Mycobacterium & Corynebaterium

Front 29

Describe Haemophilus influenzae

Back 29

G-, pleomorphic bacili found only in Humans & spread via air
6 encapsulated (smooth) types
- Type 'b' most important (95% of H. flu infections) causing septicemia, meningitis, epiglotitis, cellulitis & arthritis

Front 30

Vaccine for Haemophilus influenzae?

Back 30

Composed of PRP (polyribool phosphate) from capsule congugated to protein, given in 3 doses before 6 months old.

Front 31

Can H. influenzae be cultured?

Back 31

Yes, only on chocolate agar (heated blood agar) or agar supplemented with X and V factors

Front 32

Describe Legionella pneumophila

Back 32

Fastidious G- bacilli with LPS found in water supplies & is difficult to kill. Can be aerosolized (ie dental water pik/shower)
Need cystine for growth
Causes atypical pneumonia (Legionnaires disease) from inflammation --> capillary leakage, cell lysis. Can lead to Multi-organ disease & death.

Front 33

Pneumonic: The three sisters 'ella in the Cystine chapel

Back 33

3 bacteria that require cystine in environment for growth:
Brucella, Legionella & Francicella

Front 34

Gram negative rods that are bioterrorism concerns:

Back 34

Category A pathogens: Yersinia Pestis & Francicella tularensis

Category B: Brucella & Yersinia entercolitica

Front 35

Describe Yersinia Pestis

Back 35

G- rod, grow on normal media, facultative anaerobe (enerobacteriaceae), safety pin shape when stained

Causes Sylvatic ("wild") and Urban plague

Front 36

Describe Fransisella Tularensis

Back 36

G- rod in rodent & arthropod resevoirs, in humans causes Tularemia/Rabbit Fever (can be fatal - Ulcers, "bubos" respitory disease

Front 37

Describe Brucella

Back 37

Genus of Zoonoses. G- rod vauses Undulant fever/MaltaFever/Brcellosis - fever & nonspecific symtoms ("flu-like")

Front 38

Describe Bartonella

Back 38

Genus of G- fastidious bacilli causing Trench fever & Cat Scratch Disease

Front 39

Describe Bordetella Pertussis

Back 39

Very fastidious G- rod found only in Humans, causing "Whooping cough" & spread through close contact/aerosols

Front 40

what are the two growth factors (specifically) required for culturing of H.influenzae? where are these factors present?

Back 40

X (hematin or hemin)
V (NAD or NADPH)

they are found in lysed blood, so chocolate agar is an appropriate medium.

Front 41

what is the mechanism of legionella pneumophila?

Back 41

it is first engulfed by a macrophage;
then it inhibits phagolysosome fusion and produces proteolytic enzymes which lyse the vacuole and kill the macrophage.

Front 42

how is pneumonic plague transmitted? what is the mortality rate?

Back 42

inter-human transmission. 90% mortality.

Front 43

what is the function of the 'bubo' in yersinia pestis?

Back 43

the organism is protected within mononuclear cells (also replicates) and upon lysis, the bacilli released are fairly resistant to phag. they cause an inflammatory response in the bubo.

Front 44

which group A terrorism threat pathogen is related to "lawn-mowing" danger? how does this work?

Back 44

francicella tularensis can cause 'respiratory disease' via contamination of grass with rodent urine/feces.

Front 45

what sort of tissue does brucella have a predilection for? what can this lead to?

Back 45

brucella has a predilection for erythritol, found in animal breast, uterus, placenta and epididymus. growth in these tissues can lead to abortion sterility or asymptomatic carriage.

Front 46

describe the pathogenesis of b.pertussis.

Back 46

b.pertussis attach to ciliated epithelium of the bronchial tree and multiply. it is NOT invasive, but produces an AB toxin which causes altered signal transduction.

Front 47

what are the three disease stages of b.pertussis?

Back 47

1. catarrhal (cold-like)
2. paroxysmal (cough)
3. convalescent (non-infectious, 2ndary complications present)