what are bacteria?
bacteria are single-celled organisms, microscopic that exist there as independent or free-living organisms.
bacteria also called germs, bacteria that are everywhere, that can live in water, environment, body e.t.c some bacteria are good for and some are harmful that means some can not cause diseases.
Classification of bacteria
Bacteria are classified according to:
1. Biological classification- Observable characters like physiological, immunological and
Ecological.
2. Morphological classification:
-Higher bacteria are sub-classified into two major groups:
- Vegetative mycelium fragments include: Anaerobic, acid-fast, Anaerobic non- acid-fast
- Vegetative mycelium which does not fragment into a bacillary or coccoid form
- Lower or true bacteria
Are unicellular and never form mycelium.
They are grouped based on their shape:
- Cocci – spherical
- Bacilli – rod-shaped
- Vibrio – comma-shaped
- Spirilla – spiral twisted non-flexuous rods
- Spirochaetes- thin spirally twisted, flexuous rods
Mycobacteria
Bacteria which are acid-fast bacilli based on staining reaction to Ziehl – Neelsen stain
They are also weak Gram-positive bacilli.
Escherichia
Are Gram-negative rods usually motile
Morphological features of Mycobacterium species and Escherichia coli
1. Mycobacterium tuberculosis
-Mycobacterium is slender, rod-shaped, non-spore-forming, nonmotile, and non-capsulated straight or slightly curved measuring 1 – 4 by 0.2 – 0.5 µm containing waxy material (mycolic acid) in its wall.
2. Mycobacterium leprae
-Is a non-motile, non-sporing, straight or slightly curved rod measuring 0.2 – 0.5 x 5 –8 µm
- The organisms can be found singly and in groups called globe
Mycobacterium species in a ZN- Stained smear
3. Escherichia coli
-A gram-negative, non-capsulated, short, bacillus (rod) 2-4 µ x 0.4 to 0.7 µm in
diameter, appear singly or clustered
- Motile, non-spore-forming bacterium
Common species of medical importance
(a) Mycobacterium Species
- Mycobacterium tuberculosis
- Mycobacterium leprae
(b) Escherichia species
- Escherichia coli
Modes of transmission of mycobacterium species and Escherichia coli
(a) Mycobacterium tuberculosis
-Transmitted through inhalation of air droplets from an infected individual by coughing,
sneezing or talking.
- A cough or 5 minutes of talking can produce 3000 droplets
(b) Mycobacterium leprae
-Leprae bacilli are obligate parasites of man
-Portal of entry is most probably skin and nasal mucosa
-It needs close and prolonged contact with infective patients for contact
(c) Escherichia coli
-Contaminated water
-Contamination of body sites(urinary, wound, blood)
Diseases caused by Mycobacterium species and Escherichia coli
(a) Mycobacterium specie
-Tuberculosis (Pulmonary and extra-pulmonary)
-Leprosy
(b) Escherichia coli
-Urinary Tract Infections (UTI)
-Wound infections
-Bacteraemia & Meningitis especially of the newborn
-The diarrhoeal disease is especially in infants, but also in adults
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