Common Bacteria causing high Infectious Diseases (Staphylococci, Streptococci, and Treponema species.)
Bacteria.
• Microscopic, single-celled organisms that thrive in diverse
environments.
• They can live in soil, the ocean, the air, and inside the
human gut.
• They are classified into five groups according to their
basic shapes.
• They include spherical (cocci), rod (bacilli), spiral (spiral),
comma (vibrio’s), or corkscrew (spirochetes).
• They can exist as single cells, in pairs, chains, or
clusters
Picture of bacteria
A bacterial cell
includes:
• Capsule: Layer found on the outside of the cell wall in
some bacteria.
• Cell wall: a layer made of peptidoglycan, gives the
bacteria its shape, located outside the plasma membrane, it is thicker in some
bacteria, called Gram-positive bacteria.
• Plasma membrane: Found within the cell wall, generates
energy & transports chemicals, it is permeable (substances can pass through
it).
• Cytoplasm: A gelatinous substance inside the plasma
membrane, contains genetic material & ribosomes.
• DNA: contains all the genetic instructions used in the development & function of the bacterium, located inside the cytoplasm.
• Ribosomes: Synthesizes proteins.
• Flagellum: used for movement, to propel some types of
bacteria.
• Pili: hair-like appendages on the outside of the cell, allow
it to stick to surfaces and transfer genetic material to other cells, contributing
to the spread of illness in humans.
Examples of bacteria
include:
- Staphylococcus species
- Streptococcus species
- Clostridium species,
- Mycobacterium species,
- Bacillus species,
- Salmonella species,
- Neisseria species
Classification of
Staphylococci, Streptococci, and Treponema
Staphylococci are in the group of cocci (spherical) appear
in groups called clusters
Streptococci are also the group of cocci (spherical)
arranged in chains
Treponema species are spirochetes group that appear thin spirally twisted, flexuous rods
Morphological
features of Staphylococcus, streptococcus, and Treponema Species
(a) Staphylococci
a spherical organism
which is nonmotile, non-encapsulated, gram-positive coccus, about
1µm in diameter.
Staphylococci appear in groups called clusters.
b) Streptococci
Streptococci are spherical 0.5 – 1.0 µm and divided by
fission, but they remain attached
and so grow in beadlike chains.
Streptococci are gram-positive, non-motile, and non-sparing.
(c) Treponema
Small, delicate, tightly coiled spirochetes, measuring 6 x
15 x 0.2µ Cannot be observed by transmitted light (ordinary), Can be observed
by dark-field microscope, or fluorescence microscope only
Common Pathogenic
Species of Staphylococcus, Streptococcus, and Treponema species
- Staphylococcus aureus
- Streptococcus pyogenes, and Streptococcus pneumonia
- Treponema pallidum
Modes of Transmission
of Staphylococcus, Streptococcus, and Treponema species
(a) Staphylococcus aureus
- Direct or Indirect contact with an infected person
- Ingestion of contaminated food (poisoning from Staphylococci toxins)
- Carried on the hands of healthcare personnel
- Contaminated surfaces and medical equipment
(b) Streptococcus pygenes and streptococcus pneumonia
- Inhalation of droplets
- Inhalation of organisms as neonate passes down the birth canal
(C) Treponema pallidum
- Sexual
- Congenital
Diseases caused by
Staphylococci species
(a)Staphylococci
- Abscesses
- Skin disorders- impetigo, boils, Styes
- Conjunctivitis, especially in newborns
- Systemic, cross-infection in hospitals, septicemia, endocarditis, pneumonia, empyema,
- osteomyelitis, mastitis
- Food poisoning
- Scalded skin syndrome in young children
(b) Streptococcus species
(i) In newborn
- Pneumonia
- Meningitis
- Respiratory diseases
- Skin infection
(ii) In adult
- Endocarditic
- Septicemia
- Meningitis
- Arthritis
- Wound sepsis
(c)Treponema-The causative agents of syphilis and yaws
Key Point here, There are Bacteria Medical Importance that is
Mycobacterium Species, Staphylococcus species, Klebsiella, Haemophilus Influenzae, Salmonella species, Streptococcus
species,, e.t.c
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