بسم الله الرحمن الرحيمبسم الله الرحمن الرحيم

GENUS: MYCOBACTERIUMProf. Khalifa Sifaw Ghenghesh

Obligate aerobe, Gram-positive rods Acid fast Complex cell wall lipids

– include mycolic acids– protects vs. phagolysosomal components

Peptidoglycan, glycolipids – acid-fastness

Two major groups: – Slow growers:– Rapid growers:

Mycrobacterium tuberculosis Mycrobacterium tuberculosis

Non-motile, Non-sporing, non-capsulate rods

Grows on several enriched culture media:– Lowenstein-Jensen medium:

Whole egg, Glycerol, Asparagine, Mineral salts, Malachite green

Mycobacterium bovis:

Lowenstein-Jensen Plate Culture Inoculated with 15 Strains of Mycobacterium Species

Lowenstein-Jensen Plate Culture Inoculated with 15 Strains of Mycobacterium Species

CULTURE CHARACTERISTICS CULTURE CHARACTERISTICS

On primary isolation: – visible growth after up to 8 weeks

Colonies: – Buff colour, dry bread crumb-like appearance – Growth is eugonic (M. bovis = dysgonic)

Growth temperature:– 35-37oC

Obligate aerobe--------------------------------------------------------------------------- Heat-sensitive Susceptible to alcohol, glutaraldehyde and

formaldehyde.

Some differential characteristics of tuberculle bacilli causing human disease

Some differential characteristics of tuberculle bacilli causing human disease____________________________________________________

Species Atmospheric

preference Nitratase TCH Pyrazinamide

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M. tuberculosis Aerobic + S S

M. bovis Microaerophilic -- R R

_______________________________________TCH = thiophen-2-carboxylic acid hydrazide

S = sensitive, R = resistant

THE DISEASE THE DISEASE

Not highly contagious:– transmission with prolonged contact

between susceptible and active case–usually transmitted by airborne droplets,

must penetrate deep into respiratory tree

– infection can be via other routes:ingestion => infection through cervical

or mesenteric LN

Virulence– Ability to Survive within Macrophages

Primary TuberculosisPost-Primary Tuberculosis

Stages of Primary Tuberculosis in Childhood

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Stage Time (from onset) Characteristics

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1. 3-8 weeks Primary complex (PC) develops and tuberculin conversion occurs

2. 2-6 months Progressive healing of PC, possibility of pleural

effusion

3 6-12 months Possibility of miliary or meningeal tuberculosis

4 1-3 years Possibility of bone or joint tuberculosis

5 3-5 years Possibilty of genito-urinary or chronic skin tuberculosis

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Main differences between primary and post-primary

tuberculosis in the non-immunocompromised patients---------------------------------------------------------------------------------

Characteristics Primary Post-primary

---------------------------------------------------------------------------------Local lesion Small Large

Lymphatic involvement Yes Minimal

Cavity formation Rare Frequent

Tuberculin reactivity Negative (initially) Positive

Infectivity Uncommon Usual

(pulmonary cases)

Site Any part of lung Apical region

Local spread Uncommon Frequent

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TUBERCULIN TESTTUBERCULIN TEST

Tuberculin: a heat-concentrated filtrate of a broth in which tubercle bacilli had been grown.

Injection of tuberculin into the skin >>– Large, indurated reactions >>Post-Primary

Tuberculosis.– No induration >> Protective immunity

Purified Protein Derivatives (PPD):– Mantoux Method (Intracutaneous)– Heaf Method (Spring-loaded gun)– Tine Tests (Disposable single tests)

Mycobacteria-Positive PPDMycobacteria-Positive PPD

LABORATOY DIAGNOSIS LABORATOY DIAGNOSIS

1. Specimen:– Pulmonary tuberculosis: > Sputum, Bronchial

washings, Laryngeal swabs, and Early-morning gastric aspirates.

– Homogenized tissue biopsies.

– Examine after centrifugation: Deposits of CSF, Pleural fluid, Urine and other fluids

2. Microscopy:– Ziehl-Neelsen Stain– Fluorescent dyes

3. Culture:– Decontamination: – Lowenstein Jensen medium

4. Nucleic Acid Methods:

Mycobacterium tuberculosis sputum smear (Ziehl-Neelsen

stain)

Mycobacterium tuberculosis sputum smear (Ziehl-Neelsen

stain)

Mycobacterium tuberculosis in a sputum smear (Ziehl-

Neelsen stain)

Mycobacterium tuberculosis in a sputum smear (Ziehl-

Neelsen stain)

Mycobacteria - Auramine Stained and Viewed with Fluorescence Microscopy.

Acid Fast Bacilli Appear as Glowing Yellow Rods.

Mycobacteria - Auramine Stained and Viewed with Fluorescence Microscopy.

Acid Fast Bacilli Appear as Glowing Yellow Rods.

Histopathology of Tuberculosis, Endometrium. Ziehl-Neelsen Stain.

Histopathology of Tuberculosis, Endometrium. Ziehl-Neelsen Stain.

An anteroposterior X-ray of a patient diagnosed with advanced bilateral pulmonary

tuberculosis.

An anteroposterior X-ray of a patient diagnosed with advanced bilateral pulmonary

tuberculosis.

TREATMENT TREATMENT

Chemotherapy Recommended by International Union againstTuberculosis and Lung Disease (examples)----------------------------------------------------------------------------------------------------------Intial phase Continuation Regimen(2 months) phase (4 months)Drug Drug----------------------------------------------------------------------------------------------------------HRZ HR StandardHRZ H3R3 Intermittent/ whenHRZ H2R2 supervision is indicatedHRZE HR When there is a highHRZS HR incidence of initial drug

resistance----------------------------------------------------------------------------------------------------------H=isoniazid, R=rifampicin, Z=pyrazinamide, E=ethambutol, S=streptomycin -

EPIDEMIOLOGY EPIDEMIOLOGYTransmission:

– Open Pulmonary Tuberculosis

– Crowdness in homes and workplaces

Tuberculosis and AIDS

Tuberculosis in Developing Countries:

–Africa

CONTROL CONTROL

Early Detection and Treatment of Open Cases

Reducing Overcrowding

Vaccination:– Bacille Calmette-Guerin (BCG)

– Not effective as control measure

Mycobacterium leprae Mycobacterium lepraeLeprosy (Hansen's disease)

– A chronic intracellular infectious disease unique to man (with few exceptions). Usually not fatal.

Never been cultivated in vitroArmadillos:

– 1010 bacilli/gram of diseased tissue

M. leprae can be grown in mouse foot pads or the nine-banded armadillo (picture).

M. leprae can be grown in mouse foot pads or the nine-banded armadillo (picture).

PATHOGENESIS PATHOGENESIS

Schwan cell >> Nerve damage >> Anaesthesia and Muscle paralysis >> Gradual destruction of extremities

> Nasal bones and eyes

Immune reactions >>

–Severe and permanent nerve damage

THE DISEASETHE DISEASE Manifestations of the disease depend on the

resistance of the host.

1. Tuberculoid: host is highly resistant, clinical abnormalities limited to a few peripheral nerves and adjacent skin areas, tuberculoid granuloma

2. Lepromatous: host lacks resistance, all tissues affected, foam cell granuloma

3. Borderline:

The feet become subject to bone damage and deformity through

unnoticed wounds and infection. Serious infections can lead to

amputations.

The feet become subject to bone damage and deformity through

unnoticed wounds and infection. Serious infections can lead to

amputations.

Victims of leprosy often suffer amputations of fingertips and toes due to unfelt trauma.

X-rays of different stages.

Victims of leprosy often suffer amputations of fingertips and toes due to unfelt trauma.

X-rays of different stages.

Leprosy affects facial nerves > loss of blinking reflex of the eye > dryness, ulceration, and

blindness.

Leprosy affects facial nerves > loss of blinking reflex of the eye > dryness, ulceration, and

blindness.

Lepromatous lesions on human backLepromatous lesions on human back

LABORATORY DIAGNOSISLABORATORY DIAGNOSIS Histological Examination of Skin Biopsies Detection of Acid-Fast Bacilli:

– In Nasal Discharges

– Scrapings from Nasal Mucosa

– Slit-Skin SmearsSuperficial incisions in skin >>

Bacillary Index (BI):

Bacillary Index (BI) 1+ 1-10 bacilli/100 fields 2+ 1-10 bacilli/10 fields 3+ 1-10 bacilli/ field 4+ 10-100 bacilli/ field 5+ 100-1000 bacilli/ field 6+ >1000 bacilli/ field

Morphological Index (MI):

TREATMENTTREATMENT

WHO Recommendations for Multidrug Therapy-----------------------------------------------------------------------------------------------Type of Drug Dose Frequency TotalLeprosy (mg) Duration-----------------------------------------------------------------------------------------------Paucibacillary Rifampicin 600 Monthly, Superv. 6 months

Dapsone 100 Daily, unsuperv.

Multibacillary Rifampicin 600 Monthly, Superv. >2 yearsDapsone 100 Daily, Unsuperv.

300 Mothly, Superv.

Clofazimine {+50 Daily, Unsuperv.

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EPIDEMIOLOGYEPIDEMIOLOGY Transmission:

– Nasal secretions of patients with lepromatous leprosy.

Skin Test: Limited diagnostic value– Lepromins > boiled-bacilli rich lepromatous lesions– Leprosins > ultrasonicates of tissue-free bacilli from

lesions.

Two Types of Reaction:– Fernandez Reaction: sensitized individuals > 48h

(leprosin)

– Mitsuda Reaction: granulomatous swelling > ~3 weeks (lepromin)

بسم الله الرحمن الرحيمبسم الله الرحمن الرحيمبسم الله الرحمن الرحيمبسم الله الرحمن الرحيم

ACTINOMYCETESACTINOMYCETES

Gram +ve, Filaments that Break Up Into Bacillary and Coccoid Forms.

Non-Motile, Non-Sporing, Non-Capsulated.

Free Living >> Soil

1. ACTINOMYCES SPECIES 1. ACTINOMYCES SPECIES

A. israelii– Actinomycosis >>

Chronic Granulomatous Infection.– Formation of Sulphur granules:

3 Forms: i. Cervicofacialii. Thoraciciii. Abdominal

Predisposing Factors: Trauma, Poor Oral Hygiene.

A. israeliiGram stain showing diphtheroidal

rods and short branching filaments.

A. israeliiGram stain showing diphtheroidal

rods and short branching filaments.

Actinomycosis-organisms aspirated from the lung. Long, tortuous and branching organisms can easily be visualized using silver stain. Sulfur granules not seen in aspirations.

Actinomycosis-organisms aspirated from the lung. Long, tortuous and branching organisms can easily be visualized using silver stain. Sulfur granules not seen in aspirations.

LABORATORY DIAGNOSISLABORATORY DIAGNOSIS

i. Direct Examination:

Sputum, Pus, etc.. >> Examined for Granules

ii. Culture: Brain Heart Infusion Agar

TREATMENT– Penicillin >> Several Weeks

Sulfur granule from human actinomycosis tissue section (hematoxylin and eosin stain).

Sulfur granule from human actinomycosis tissue section (hematoxylin and eosin stain).

2. NOCARDIA SPECIES2. NOCARDIA SPECIES

N. asteroides– Nocardiosis.

Aerobic. Disease Begins as Pulmonary Infection > > 50% of Patients are Immunocompromised. Fatality Rate >>

LABORATORY DIAGNOSISLABORATORY DIAGNOSIS

i. Direct Examination: Sputum, Skin Lesions, Tissue Biopsies or Surgical Material

>> Microscopically. Observe: G+ve, Multiple Branched and Beaded Filaments. > Partially Acid-Fast. ii. Culture: iii. Identification: Biochemically.

TREATMENT Sulphonamides, NA, TMP-SMX.

Nocardia asteroidesSilver stain showing the twisted

masses of long filamentous organisms

Nocardia asteroidesSilver stain showing the twisted

masses of long filamentous organisms

Nocardia asteroidesAcid fast stain shows the pale red staining organisms in an area of

necrosis

Nocardia asteroidesAcid fast stain shows the pale red staining organisms in an area of

necrosis

Differences between the genera

Actinomyces and Nocardia

------------------------------------------------------------------Actinomyces species Nocardia species

------------------------------------------------------------------Facultative anaerobes Strict aerobes

Grow at 35-37oC Wide temp range of growth

Oral commensals Environmental saprophytes

Non-acid-fast mycelia Usually weakly acid-fast

Endogenous cause of Exogenous cause of disease

Disease

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