Imagine that someone picking up roses in a garden gets a scratch from a thorn. Some bacteria (Staphyloccocus aureus and Streptococcus pyogenes) take advantage of the wound to gain access to the deeper layers of the skin and attempt to cause an infection. Describe the different stages of the host response (in particular the types of cells and receptors involved) and how the bacteria will be recognized and eliminated. Solution The superficial staphylococcal and streptococcal infections are very common in skin. The physiological condition of the skin is much suitable to these bacteria. Both these bacteria are potent toxin and enzyme producing strains. S.auresus infection on the skin immediately stimulates the inflammatory response and macrophages and neutrophils are proliferated at the site of infection. The organism can enter the body through openings in the skin barrier like hair follicles and can cause infections like folliculitis, pimples, furuncle which is type of abscess. The furuncles also damage the neighboring tissue by invading deep in to the tissue. This is known as carbuncle. Staphylococci cause a highly contagious skin infection in children known as impetigo. The impetigo is two types-nonbullous impetigo is caused by both S.aureus and S.pyogenes; bullous impetigo is caused by staphylococcal toxin. It is also known as staphylococcal scalded skin syndrome. At later stages of toxic shock syndrome the scalded skin syndrome is the characteristic feature. Streptococci also secrete toxin and enzymes. The toxins are called hemolysins that lyse the red blood cells. Various hemolysins like alpha, beta and gamma are produced by various streptococcus strains. S.pyogenes is an important beta hemolytic streptococcus. Streptococcus skin infections are generally superficial but some times may reach the deeper tissues also. S.pyogenes infects the dermis of the skin and also causes a disease known as erysipelas in which the skin erupts in to reddish patches. The skin scraping is cultured and stained to observe the bacteria under microscope. Staphylococci and streptococci both are gram positive and round shaped bacteria. The staphylococci occur as grape-like clusters (Staphylococci name indicates bunch of grapes in Greek). The streptococci are arranged in chains or pairs. Topical antibiotics like Mupirocin and oral antibiotics like first generation cephalosporins and erythromycin are used to eliminate the bacteria..

1. Imagine that someone picking up roses in a garden gets a scratch from a thorn. Some bacteria
(Staphyloccocus aureus and Streptococcus pyogenes) take advantage of the wound to gain access
to the deeper layers of the skin and attempt to cause an infection. Describe the different stages of
the host response (in particular the types of cells and receptors involved) and how the bacteria
will be recognized and eliminated.
Solution
The superficial staphylococcal and streptococcal infections are very common in skin. The
physiological condition of the skin is much suitable to these bacteria. Both these bacteria are
potent toxin and enzyme producing strains.
S.auresus infection on the skin immediately stimulates the inflammatory response and
macrophages and neutrophils are proliferated at the site of infection. The organism can enter the
body through openings in the skin barrier like hair follicles and can cause infections like
folliculitis, pimples, furuncle which is type of abscess. The furuncles also damage the
neighboring tissue by invading deep in to the tissue. This is known as carbuncle. Staphylococci
cause a highly contagious skin infection in children known as impetigo. The impetigo is two
types-nonbullous impetigo is caused by both S.aureus and S.pyogenes; bullous impetigo is
caused by staphylococcal toxin. It is also known as staphylococcal scalded skin syndrome. At
later stages of toxic shock syndrome the scalded skin syndrome is the characteristic feature.
Streptococci also secrete toxin and enzymes. The toxins are called hemolysins that lyse the red
blood cells. Various hemolysins like alpha, beta and gamma are produced by various
streptococcus strains. S.pyogenes is an important beta hemolytic streptococcus. Streptococcus
skin infections are generally superficial but some times may reach the deeper tissues also.
S.pyogenes infects the dermis of the skin and also causes a disease known as erysipelas in which
the skin erupts in to reddish patches.
The skin scraping is cultured and stained to observe the bacteria under microscope.
Staphylococci and streptococci both are gram positive and round shaped bacteria. The
staphylococci occur as grape-like clusters (Staphylococci name indicates bunch of grapes in
Greek). The streptococci are arranged in chains or pairs. Topical antibiotics like Mupirocin and
oral antibiotics like first generation cephalosporins and erythromycin are used to eliminate the
bacteria.