MICROBIOLOGY PPT LECTURE NOTES | Karya Tulis Ilmiah

(1)

Mycobacterium

(2)

MYCOBACTERIUM

THIS GENUS IS COMPOSED OF:

Strictly aerobic, acid-fast rods, does not Stain well (gram stain indeterminant),

DNA has high g+c content, unique cell wall, Mycolic acid carbon chain length > c60

Relatively slow growth (two groups)

A. RAPID GROWERS (Visible colonies in <5 days)

B. SLOW GROWERS (Visible colonies in > 5 days)

(3)

THE GENUS MYCOBACTERIUM CAN BE DIVIDED INTO FOUR BROAD GROUPS

THE GENUS MYCOBACTERIUM CAN BE DIVIDED

INTO FOUR BROAD GROUPS

1. THE TUBERCULOSIS COMPLEX

2. SLOW GROWING MYCOBACTERIA

OTHER THAN TUBERCULOSIS (MOTT) 3. RAPIDLY GROWING MYCOBACTERIA

(4)

Acid Fastness Stain

(Ziehl-Neelsen stain)

 flood the slide with basic

fuchsin (a red dye) in 5% phenol as a mordant.

 heat gently for few minutes to

melt the wax.

 wash with 3% HCl in ethanol.  counter-stain with methylene

blue.

Mycobacterium stains red and other bacteria and the background are blue. The mycolic acid and its derivatives are responsible for the acid f

(5)

THE TUBERCULOSIS COMPLEX

(Organisms that resemble M. tuberculosis;

Causing a similar type of disease in humans)

1. M. tuberculosis 2. M. bovis

(6)

Mycobacterium tuberculosis

(7)

M. . tuberculosistuberculosis

General Features

 It is a causative agent for human

tuberculosis.

 It grows very slow with a

generation time of 12-15 hours.

 On solid media the colonies are

raised and rough with a wrinkled surface.

 M. tuberculosis cells grow either

as discrete rods or as aggregates. Virulent strains tend to grow as an aggregated long arrangement called serpentine cord. Cord

factor is a derivative of mycolic acids, trehalose 6'-dimycolate.

(8)

Resistance

Resistance::

UV Malachite

green(1:13000)

Alcohol (to nonspore-forming bacteria) 3%HCL, 6%H2SO4,

4%NaOH (15min)

Heat(62-63℃,15min) Chemical disinfectants (more) Wet Dry (highly) Sensitive Not sensitive

EUGONIC GROWTH 14 DAYS DYSGONIC GROWTH 14 DAYS

Mycobacterium tuberculosis Mycobacterium bovis

COLONIAL MORPHOLOGY OF THE

TUBERCULOSIS COMPLEX MYCOBACTERIA

COLONIAL MORPHOLOGY OF THE COLONIAL MORPHOLOGY OF THE

TUBERCULOSIS COMPLEX MYCOBACTERIA TUBERCULOSIS COMPLEX MYCOBACTERIA

(9)

Transmission

Through

respiratory tract, alimentary

tract, injured skin

。

TB in the lungs or throat can be infectious.

This means that the bacteria can be spread

to other people. TB in other parts of the

body, such as the kidney or spine, is usually

not infectious.

(10)

Who is at risk:

Primary infection: children

Secondary infection: age>25

(11)

Virulence factors

No spore, no flagellum, no exotoxin,no endotoxin, no invasive enzyme

Capsule:polysaccharide;CR3;enzyme;

protect

Lipid/Lipo arabinomannan

Heat-shock protein/Tuberculin

protein: antigenicity, old tuberculin;

associate with wax D can cause

(12)

Lipid

Lipid: closely related to virulence

a. Phospholipid

monocytes proliferate,cause tubercles b. Wax D

adjuvent(not only to TB), delayed-type hypersensitivity

c. Sulfatide 硫酸脑苷脂

suppress phagosome combine with lysosome

d. Cord factor (trehalose-6,6-dimycolate)

destroy mitochondria, cause chronic

(13)

Pathogenesis

primary infection

1) lung infection

secondary infection

2) Out lung infection

(14)

Clinical syndromes

a.

fatigue, weakness, weight loss and fever

b. pulmonary involvement: chronic

cough,spit blood

c. meningitis or urinary tract involvement

d. bloodstream dissemination: miliary

tuberculosis with lesions in many organs

and a

high mortality rate

.

(15)

Primary Tuberculosis

 The organisms are transmitted

among human via aerosol.

 TB bacilli lodge in the alveoli

or lung alveolar ducts and most of bacilli are

phagocytosed by alveolar macrophages.

 _{Macrophages migrate to the}

hylar lymph node and generate T cell-mediated immune response.

(can be monitored by tuberculin test)

(16)

Tuberculin Skin Test

 Tuberculin is a mixture known as purified

protein derivatives (PPD) from TB bacilli.

 It is a test for delayed type hypersensitivity.

Positive reaction, reddening and thickening (> 5mm) at the site of injection after 2-3

days, indicates cellular immunity to tubercle

(17)

 Macrophages containing TB bacilli clump together and begin to form tubercles. (granulomatous response)  With time, the centers of the

tubercles become necrotic and form cheesy acellular masses of caseous materials. (caseous lesion)

Symptoms:

Activation of macrophages -> cytokine secretion, IL-1: fever, TNF: lipid metabolism, weight loss, tissue necrosis. Oxygen radicals: tissue damages

Tissue necrosis -> inflammation -> mucous secretion, destruction of

blood vessels -> frequent cough and bloody sputum PULMONARY TUBERCULOSIS

PULMONARY TUBERCULOSIS

Large caseating tubercle Miliary tubercles

HUMAN LUNG

HUMAN LUNG HUMAN LUNGHUMAN LUNG

TUBERCULOSIS TUBERCULOSIS

(18)

MYCOBACTERIUM TUBERCULOSIS

Can infect (disseminate) and cause disease in many different body locations such as: 1. Meninges

2. Brain 3. Bone 4. Kidney

(19)

Bacteria coughed up in sputum

Inhalation of bacteria

Bacteria reach lungs, enter macrophages

Bacteria reproduce in macrophages

Lesion begins to form (caseous necrosis)

Activated macrophages Bacteria cease to grow; lesion calcifies Immune suppression Reactivation Lesion liquefies Dead phagocytes, necrosis M. tuberculosis Phagocytes, T cells, and B cells trying to kill bacteria Death Spread to blood organs

(20)

(21)

Immunity

High rate of infection, but low morbidity.

 Nonspecific immune

AIDS, immunosuppressive agents, endocrine disease, etc.

(22)

Immunity-Immunity-

cellular Immunity

First time: TB invade→proliferate on the spot →invade local lymph node

Macrophage engulf TB →TH cell

→IL-1 → TH proliferate →bloodstream

Then TH meet TB again

→MCF →macrophages congregate to focus →MAF →macrophages become more active →MIF →macrophages stay at the focus

Then if it is successful granulomatosis forms,prevent TB

diffusing;If it is not successful,macrophage can not kill TB, patients deteriorate.

(23)

Immunity

Cellular immunity

3-6 weeks, T cell VS macrophage

1. CD4+T_H : INF-γ→macrophage→epithelioid cell

granulomatosis

2. CD8 +T_S: granule dependent, dissolve infected

macrophage,kill TB

3. CD4- CD8 –t(γδ-T):Fas dependent, dissolve

infected macrophage,but not kill TB, cause caseous focus in the center of granulomatosis;

(24)

Immunity

IV hypersensitivity

Koch phenomenon;

wax D+tuberculin protein;

wax D →macrophage→epithelioid

cell→tubercles→protect TB being

phagocytized

(25)

Immunity

Humoral immunity

A lot of Ab comes out, but meaningless

TB active patient:

immune complex more

(26)

Diagnosis

The steps to diagnose TB infection and

disease include:



A medical evaluation that includes

history and risk assessment



The tuberculin skin test



A chest x-ray

(27)

Diagnosis

1. Specimen: sputum, pus, CSF, urine, etc.

2. Microscopic examination: Ziehl-Neelsen stain

3. Concentration: 4%NaOH-3%HCL; 6% H2SO4

4. Culture:

solid culture (2-4 weeks 37℃) ; liquid culture (1-2 weeks)

5. Animal inoculation: guinea pig

(28)

Skin test

PPD-C

BCG-PPD

>5mm +

>15mm + +

(29)

Mantoux method

When the Mantoux skin test is performed, a

needle is injected into the upper skin layer of the patient's arm. The arm is examined 48 to 72 hours after the tuberculin injection in

order to evaluate the reaction on the patient's skin. Any swelling that can be felt around the site of the injection, also known as

induration, is measured. The diagnosis of TB infection depends on the size of the measured induration and the patient's individual risk factors.

(30)

Prevention

BCG vaccination for new infants Freeze-drying vaccine

rRNA vaccine

eg:south India Chingleput’s failure of BCG

(31)

Treatment for Tuberculosis



Treated with a combination of multiple

drugs for a long period of time: rifampin,

isoniazid (INH), pyrazinamide, ethambutol,

and streptomycin.



Emergence of multi-drug resistant M.

(32)

Mycobacterium avium

and

_and

AIDS

(33)

•

M. avium _{M. avium}is much less virulent than is much less virulent than M. tuberculosisM. tuberculosis

– _{does not infect healthy people}_{does not infect healthy people} – _{infects AIDS patients}_{infects AIDS patients}

• _{M. avium}_{M. avium}_infects_infects

– _{when CD4 count greatly decreased}_{when CD4 count greatly decreased}

• _{M. tuberculosis}_{M. tuberculosis}_infection_infection – infects healthy people_{infects healthy people}

– _{infects AIDS patients}_{infects AIDS patients}

* earlier stage of disease_{earlier stage of disease}

* _{more systemic}_{more systemic}

Mycobacteria and AIDS

(34)

• _{systemic disease (versus pulmonary)}

–

_{greater in AIDS}

• _{lesions often lepromatous}

Clinical features with AIDS

Antibiotic therapy

• _{selected primarily for}

_{M. tuberculosis}

(35)

Mycobacterium

avium-intracelluare

intracelluare

complex

_complex

 causes tb like disease in birds, opportunistic

 pathogen in humans. Very prominent cause of  disease in aids patients has been decreased

 following haart. Not easily transmitted.

 (Runyon group III). Difficult to treat ( drug of  choice is rifabutin)

(36)

Mycobacterium

Mycobacterium fortuitumfortuitum

complex

Causes chronic abscesses (often wound

associated)

Can be confused with M. tuberculosis Often drug resistant

 rapidly growing (Runyon group IV)

Mycobacterium

Mycobacterium kansasiikansasii

Pulmonary and disseminated disease similar

to tuberculosis (organisms do not produce niacin)

does not respond well to antimicrobials, (no

response to anti-tuberculosis therapy)

Opportunistic pathogen

Runyon group I (photochromogen)

Mycobacterium

Mycobacterium marinummarinum

Extrapulmonary ulcerative lesions Growth of organism restricted to 34oc

Disease called “swimming pool granuloma” Does not respond well to therapy

Mycobacterium

Mycobacterium ulcerannsulceranns

Does not grow above 33oc

Causes burui ulcer, emerging infectious

disease

Infection limited to fatty tissue beneath

(37)

Mycobacterium leprae

(38)

HANSEN’S DISEASE (Leprosy)

caused by

M. leprae

_{M. leprae}

 Hansen’s disease is a chronic, slowly progressive

 granulomatous disease involving ectodermally

derived

 tissue such as the skin and peripheral nerves. The

disease is usually limited to the cooler parts of the body such as the skin, nose and upper respiratory tract. It rarely affects internal organs such as the brain, liver, spleen, kidneys, and bones.

(39)

4 forms of forms of Leprosy: Leprosy: LepromatousLepromatous Tuberculoid

Tuberculoid

Borderline

indeterminate

(1)

• _{systemic disease (versus pulmonary)}

–

_{greater in AIDS}

• _{lesions often lepromatous}

Clinical features with AIDS

Antibiotic therapy

• _{selected primarily for}

_{M. tuberculosis}

(2)

Mycobacterium

avium-intracelluare

intracelluare

complex

_complex



causes tb like disease in birds, opportunistic



pathogen in humans. Very prominent cause of



disease in aids patients has been decreased



following haart. Not easily transmitted.



(Runyon group III). Difficult to treat ( drug of



choice is rifabutin)

(3)

Mycobacterium

fortuitum

complex

Causes chronic abscesses (often wound

associated)

Can be confused with M. tuberculosis Often drug resistant

 rapidly growing (Runyon group IV)

Mycobacterium

kansasii

Pulmonary and disseminated disease similar

to tuberculosis (organisms do not produce niacin)

does not respond well to antimicrobials, (no

response to anti-tuberculosis therapy)

Opportunistic pathogen

Runyon group I (photochromogen)

Mycobacterium

marinum

Extrapulmonary ulcerative lesions Growth of organism restricted to 34oc

Disease called “swimming pool granuloma” Does not respond well to therapy