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HMB202H1 Chapter Notes -Acne Vulgaris, Nephron, Radiography

Human Biology
Course Code
Jane Mitchell

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Gram Positive
Staphylokinase: dissolves fibrin threads in blood clots
Lipases: digest lipids allowing staphylococci to grow on the surface of the skin
Staphylococcus aureus: several toxins that contribute to their pathogenicity
o Cytolytic toxins: alpha, beta, gamma and delta toxins are proteins
o Exfoliative toxins: two distinct proteins cause the dissolution of epidermal
o Toxic Shock syndrome (TSS) toxin the protein causes toxic shock
o Enterotoxins: have 5 proteins stimulate the intestinal muscle
contractions, nausea, and intense vomiting
Staphylococcus epidermidis: on human skin
Bacteria can be transferred from skin
Staphylococcus causes medical problems depending on the site of infections,
immune state of its host and toxins and enzyme a particular species
Noninvasive Disease
Staphylococcus aureus: more common causes of food poisoning
Commonly affected meats, custard pastries, potato salad and ice cream
Symptoms include nausea, severe vomiting, diarrhea, headache, sweating and
abdominal pain that can last for hours
Cutaneous Disease
Staphylococcus aureus causes locailized pyogenic
Staphlococcal scalded skin syndrome: is reddening of the skin at the mouth
then spreads throughout the body
There are the large blood cells consistence with the disease
The affected layer peals the skin away
Impetigo: small, flattened red patched on the face and limbs particular children
who’s immune system are not developed
Folliculitis: is an infection of a hair follicle in which the base becomes red,
swollen and pus
Sty: condition at the eyelid
Furuncle: boil is a large painful raised nodules extention of follicu;it is into
surrounding tissue
Carbuncle: form deeper in tissues
Systemic Diseases
Can cause potentially fatal events
Staphylococcal Toxic Shock Syndrome
When strains produce TSS toxin
Fever, vomiting, red rash, low pressure and loss of sheets of skin
S. aureus is the common cause of bacteremia
Blood from a site can cause infections to the body
S. aureus may attack the lining of the heart
Typically patients can have flu-like systems
Pneumonia and Empyema

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Staphylococcus in the blood can invade the lungs causing pneumonia
Empyema: patients with pneumonia with pus
Osteomyelitis: staphylococcus invades the bone
Characterized by bone development
Latter half 20th century: genes for B-lactamase which covey resistance to natural
Methicillin-resistance Staphylococcus aureus (MRSA): major problem in health
care settings
Gram-positive bacteria
Known as S. pygenes
Streptococcus pyogenes have a number of structures, enzymes and toxins
Two main structural features allow S. pyogenes to phagocytose
o M protein: a membrane protein that interferes with oponization and lysis
o Hyaluronic acid capsule: normally found in cells -> white blood cells may
ignore bacteria “camouflage”
Researchers have identified two streptokinases that break through blood clots
Moves to infected areas
Group A: streptococcus secretes 3 pyrogenetic toxins helps stimulate
These toxins cause the blood to dilate
S. pyogenes can produce 2 different membrane bound proteins called stretolysins
which lyse red blood cells, white blood cells and palettes
Group A streptococcus infects pharynx or skin
Usually temporary lasting only adaptive immune responses
Streptococcus pyogene causes normal competing microbiota are depleted
Group A Streptococcal Diseases
Group A Streptococcus: causes a number of diseases
A sore throat can be caused by streptococcus inflammation of the pharynx
Accompanied by fever, malaise and headache
Appears red and swollen lymph nodes and purulent
There are two form of contagious and non-contagious forms
Scarlet Fever
Also known as scarlatina usually accompanies streptococcal pharyngitis
After one or two days of pharyngitis: pyrogenic toxins released by streptococci
triggered a rash on the tongue then appears on the skin
Pyoderma and Erysipelas
Pyoderma: confined, pus producing lesion that usually appears on the face, arms
or legs
Direct contact with an infected person can spread the disease
Pus-filled lesion breaks open it forms a yellowish crust
Ersipelas: streptococcal infection involves surrounding lymph nodes and triggers
pain and inflammation
Toxic-shock-like syndrome
Group A streptococci can spread rarely

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Spread leads to bacteremia and severe multisystem infections producing toxic
shock-like syndrome (TSLS)
Patients experience inflammation at the sites of infection, fever, chills, malaise,
nausea, vomiting and diarrhea
Necrotizing Fasciitis
Serious disease caused by S. pyogene
“Flesh eating bacteria”
Streptococci enter the body the skin and secretes enzymes and toxins that destroy
tissues and will destroy muscle and fat tissue
It can spread deep into the connective tissue
Involves toxins in the blood
Rheumatic Fever
Inflammation leads to damage of heart valves and muscle
The exact cause of the damage in unknown
It is an autoimmune response to S. pyogenes
Antigen of some strains of Streptococcus are not removed from circulation,
accumulation in the glomeruli of the kidney’s nephrons
Inflammation of the
Diagnosis, treatment and prevention
Streptococcus: normal in the pharynx
Use penicillin effective against S. pyogene
Group B: streptococcus: Streptococcus agalactiae
S. agalactiae forms capsules against antibodies
Produce enzymes called proteases
Colonize the lower GI tract, genital and urinary tract
Infections less than a week in newborns, 3 months
Bacteria is associated with neonatal bacteremia, meningitis and pneumonia
Diagnosis, treatment and prevention
Penicillin G is used to treat
Other Beta: Hemolytic Streptococci
Streptococcus equisimilis causes pharyngitis
Streptococcus anginoso causes pus containing abscesses
Pencillin can be used to treat both
Alpha-Hemolytic Streptococci: The Viridan Group
Lack group specific carbohydrate
Viridans streptococci produce green pigments
Normally inhabits the mouth, pharynx, GI tract and urinary tract of humans
They are opportunists that produce abdominal infections
Large quantities can create biofilm -> dangerous to teeth
Streptococcus Pneumoniae
Discovered by Lousis Pasteur in 1881
Gram positive
He classified the bacteria as diplococcus
Normal member of pharyngeal microbitia can colonize in lungs, sinuses and
middle ear
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