1. Mycobacteria Stained by Ziehl Neelsen stain
Mycobacteria is a genus within the order Actinomycetales
The main cause of human Tuberculosis (TB)
1- M. tuberculosis
2-M.bovis
Mycobacteria are Gram-positive, although they do not take gram staining well due high lipid contents of their cell wall .
Stained by Ziehl Neelsen stain
Acid fast bacilli ( resistance to decolorization by acids during staining procedures)
Mycobacterial cell walls are unusual in that they are approximately 60% lipid, including a unique class of very long-chain, hydroxylated fatty acids (mycolic acids).

2. Mycobacteria Aerobic bacilli-non spore forming Non motile ,rod shape
Intracellular parasite
Mycobacteria are also resistant to drying, but not to heat or ultraviolet irradiation
non capsulated
Very slow growing and grow well on media containing egg proteins
( Lowenstein-Jensen medium (L-J)
Cultures must be incubated for three to six or eight weeks at 37 oC.

3. Lowenstein-Jensen medium

4. Epidemiology
Patients with active pulmonary tuberculosis shed large numbers of organisms by coughing
Because of resistance to desiccation, the organisms can remain viable for a long time.
Transmission by inhalation of the aerosol,
repeated or prolonged contact is usually required for transmission
M.bovis can be transmitted through ingestion of unpasteurized milk

5. Tuberculosis Transmission
When people suffering from active pulmonaryTB can transmitt it through droplet infect coughs, sneeze, speak, or spit

6. Pathogenicity
After being inhaled, mycobacteria reach the alveoli, where they multiply in the pulmonary epithelium or macrophages.
Within 2-4weeks, many bacilli are destroyed by the immune system, but some survive and are spread by the blood to extrapulmonary sites.
when the organism engulfed by macrophages, bacterial sulfolipids inhibit the fusion of phagocytic vesicles with lysosomes.

7. Clinical significance
Tuberculosis
There are two major patterns of the disease:
1-Primary tuberculosis
Occurs in a person who has first contact with the organism
usually acquired via the respiratory tract
In majority of cases the infection becomes arrested
and the tubercle undergoes fibrosis and calcification
Alternatively, if the lesion breaks down, the caseous material is discharged, and the infection spread to other organs
active tubercles may develop throughout the body
( miliary tuberculosis)

8. Clinical significance (cont’d)
2-Secondary tuberculosis: seen mostly in adults as a reactivation of previous infection (or reinfection)
This is usually caused by M. tuberculosis that has survived in a dormant primary tubercle lesion
pulmonary sites are most common, particularly the lung apices where high oxygen tension favors mycobacterial growth.
Bacterial populations in such lesions often become quite large and many organisms are shed (for example, in sputum).
Reactivation is apparently caused by an impairment in immune status
AIDS common preconditions.

9. Clinical significance (cont’d))
Extra-pulmonary TB
It is tuberculosis of organs other than the
lungs, such as lymph nodes, abdomen,
genitourinary tract, skin, joints and
bones, meninges .

10. Tuberculosis Symptoms
Coughing up blood
Excessive sweating, especially at
night
3-Fatigue
4-Fever especially at night
5-Weight loss
6-Breathing difficulty

11. Laboratory diagnosis 1-Specimen . sputum , urine ..etc
2-Microscopic exam
ZN stain –acid fast bacilli
3-Culture
on LJ medium. .It should be
followed for 4-8 weeks
before discard .

12. Acid fast bacilli (M.tuberculosis) isolated from a patient sputum

13. M.tuberculosis , isolated from a patient sputumon LJ medium

14. Laboratory diagnosis of Mycobacterium
4- DNA probes.
5-chest X-ray
6-Tuberculin test.

15. Tuberculin Test (Montoux test )
It is a delayed-type hypersensitivity (DTH) to tuberculoprotein.
Performed by intradermal injection with PPD that is read 48 to 72 hours later.
Positive test appears as indurations of 10 mm or more accompanied by erythema
No indurations indicates a negative reaction.

16. Tuberculin test

17. Tuberculin test

18. Treatment
Always involve a combination of many drugs (usually four drugs)
The most commonly used drugs include:
Isonizid
Rifampin
Pyrazinamide
Para-aminosalicylic acid
Streptomycin

19. Prevention
Public health measures such as tuberculin tests, chest radiographs, case registries, and contact tracing have done much to control tuberculosis at the population level.
Latent TB chemotherapy: For individuals who are tuberculin-positive but asymptomatic, chemotherapy is indicated in several situations
A vaccine against tuberculosis (BCG),

20. Mycobacterium leprae
Leprosy is a chronic granulomatous condition of peripheral nerves and mucocutaneous tissues , particularly the nasal mucosa
Leprosy caused by Mycobacterium leprae
Pathogenicity:
M. leprae is transmitted from human to human through prolonged contact; for example, between exudates of a leprosy patient's skin lesions and the abraded skin of another individual

21. Clinical significance
Leprosy : occurs as a continuum between two clinical extremes:
Tuberculoid
Lepromatous leprosy
In tuberculoid leprosy, the lesions occur as large maculae (spots) in cooler body tissues such as skin (especially the nose, outer ears, and testicles), and in superficial nerve endings.
Neuritis leads to patches of anesthesia in the skin.
The patient mounts a strong cell-mediated immune response and develops delayed hypersensitivity
lepromatous leprosy: is slow but progressive Large numbers of organisms are present in the lesions and reticuloendothelial system, and immunity is severely depressed

22. Diagnosis M. leprae is an acid-fast bacillus
-Acid-fast stained scrapings or skin biopsy

23. Treatment and prevention
Several drugs are effective in the treatment of leprosy, including sulfones such as dapsone, rifampin, and clofazamine
combined therapy is necessary to ensure the suppression of resistant mutants.
vaccination with BCG

24. Spirochetes

25. Spirochetes
Spirochetes are long, slender, motile, flexible, undulating, gram-negative bacilli that have a characteristic corkscrew or helical shape
Have a unique structure that is responsible for motility
Spirochetes that are important human pathogens are confined to three genera
1- Genus Treponema
2- Genus Borellia
3-Genus Leptospira

26. Structural Features of Spirochetes

27. Treponema
T.pallidum that cause a disease known Syphilis is extremely fastidious and fragile. cannot be cultured routinely in the laboratory, and is sensitive to disinfectants, heat, and drying. T. pallidum is so thin that it cannot be observed by light microscopy, but requires immunofluorescent or dark-field techniques Secrete hyaluronidase, an enzyme that disrupts ground substance, and probably facilitates dissemination of the organism.

28. Pathogenesis Transmission of T. pallidum by Sexual contact
Transplacentally (congenital syphilis).
A break in the skin,

29. Clinical significance
Syphilis: Syphilis occurs in three stages
Primary stage
Secondary stage
A tertiary stage
1-Primary stage:
The first symptom is a hard genital or oral ulcer (chancre) that develops at the site of inoculation. This primary lesion heals spontaneously, but the organism continues to spread throughout the body via the lymph and blood. followed by the

30. Clinical significance ( cont’d)
2-Secondary stage.
This stage is characterized by the appearance of a red, maculopapular rash on almost any part of the body,
Also present are pale, moist, flat papules seen primarily in the anogenital region (condylomata lata), armpits, and mouth.
Both primary and secondary lesions are extremely infectious.
secondary stage may be accompanied by, hepatitis, meningitis, nephritis, or chorioretinitis.
Upon healing of the secondary lesions, the disease enters a latent period that can last for many years

31. Maculopapular rash on almost any part of the body,

32. Flat papules

33. Clinical significance ( cont’d)
3-A tertiary stage, In approximately 40% of infected individuals, the disease progresses to a tertiary stage, characterized by degeneration of the nervous system, cardiovascular lesions such as aneurysms, and granulomatous lesions (gummas) in the liver, skin, and bones.

34. Congenital syphilis
T. pallidum can be transmitted through the placenta to a fetus after the first 10-15wks of pregnancy.
Infection can cause death and spontaneous abortion of the fetus or cause it to be stillborn.
Infected infants who live develop a condition similar to secondary syphilis, including a variety of central nervous system (CNS) and structural abnormalities.
Treatment of the pregnant mother with appropriate antibiotics prevents congenital syphilis

35. Laboratory identification
Although treponemal spirochetes from primary and secondary lesions can be detected microscopically using immunofluorescent stain or dark-field illumination
syphilis is usually diagnosed serologically

36. Treatment and prevention
One single treatment with penicillin is curative for primary and secondary syphilis
In cases of patient sensitivity to penicillin, erythromycin or tetracyclines may also be effective
There is no vaccine against T. pallidum
prevention depends on safe sexual practices

37. Borrelia B. burgdorferi causes Lyme disease
B. recurrentis causes relapsing fever
Members of the genus Borrelia are relatively large spirochetes that, like Treponema, have endoflagella that make them highly motile
Borrelia species are unusual among bacteria in that they have linear rather than circular plasmid and chromosomal DNA.

38. Pathogenesis Lyme disease is caused by the spirochete B. burgdorferi
Transmitted by the bite of a small tick
Mice and other small rodents serve as primary reservoirs for the spirochete
Deer and other mammals serve as hosts for the ticks.

39. Clinical significance
Lyme disease occurs in three stages
The first stage: begins 3 to 32 days after a tick bite, when characteristic red, circular lesion with a clear center appears at the site of the of the bite
Flulike symptoms
The organism spreads
via the lymph or blood

40. Clinical significance ( cont’d)
Second stage
begins, Weeks to months after the onset of the disease with symptoms such as arthritis, arthralgia, cardiac complications, and neurologic complications such as meningitis.
Third stage
begins months to years later (2nd stage) with the appearance of chronic arthritis and, in a small number of patients, progressive CNS disease

41. Borrelia recurrentis B. recurrentis Causes relapsing fever
characterized by several cycles of apparent recovery, each followed by a relapse.
B. recurrentis able to change its surface protein antigens.
This ability accounts for the relapsing nature of the disease because with each relapse a new antigenic variant arises.

42. Pathogenesis & Clinical significance
Relapsing fever, is transmitted body lice
symptoms :
abrupt onset of high fever, headache, muscle pain, and general malaise.
Abundant spirochetes are present in the blood, during febrile period, .
The fever abates along with the number of spirochetes.
Apparent recovery ,followed by a recurrence of the initial symptoms.
There are many recurrences, generally with decreasing severity.
In fatal cases, the spirochete invades many organs of the body (heart, spleen, liver, kidney), with death generally due to myocarditis

43. Diagnosis and treatment
Diagnosis is usually based on the appearance of Giemsa
Tetracyclines, erythromycin, and penicillin have proven effective treatments
No vaccines are available, and prevention is best accomplished by protecting against lice.

44. Leptospira Interrogans
L. interrogans infection causes the disease leptospirosis
leptospirosis occurs worldwide (under various local names, such as infectious jaundice, marsh fever, Weil disease, and swineherd's disease),
Leptospirosis is essentially an animal disease that is coincidentally transmitted to humans:
primarily by water or food contaminated with animal urine
via small skin abrasions or the conjunctiva

45. Diagnosis and treatment
diagnosis is usually based on serologic agglutination tests and visual demonstration of the spirochetes in urine, blood, or cerebrospinal fluid.
Penicillin or doxycycline is useful if administered during the first stage of the disease, but both are ineffective later
No vaccine is currently available.
Prevention of exposure to potentially contaminated water and food helps control the transmission of L. interrogans.