Case 6 Flashcards
skin
The skin is the body’s largest organ • The skin has three main layers o Epidermis o Dermis o Hypodermis
epidermis
o Outermost and thinnest layer
o Acts as a protective barrier against mechanical injury
o Prevents loss of moisture
o Provides skin color
o Responsible for vitamin D production
o Four main types of cells
§ Keratinocytes – produce keratin
§ Melanocytes – produce melanin
§ Langerhans cells – tissue-resident macrophages
§ Merkel Cells – function as mechanoreceptors
o Composed of five layers
skin layers
o Stratum Corneum – Contain corneocytes, which are dead keratinocytes.
o Stratum Lucidum – Contains dead keratinocytes. Only present in the palms and soles.
o Stratum Granulosum – Keratinocytes secrete lamellar bodies to form a water barrier.
o Stratum Spinosum – contains desmosomes for strength and Langerhans cells for
immunity.
o Stratum Basale – Where stem cells proliferate to keratinocytes. Also where Merkel cells
for light touch sensation, and melanocytes for melanin synthesis are held.
*come lets get sun burned
dermis
Thickest layer
o Made up of two layers
§ Thin upper layer called the papillary dermis
§ Thick lower layer called the reticular dermis
§ The papillary dermis contains loose connective tissue,
collagen, and elastin fibers
§ The reticular dermis contains dense connective tissue, hair
follicles, and nerve endings
o Regulates body temperature and provides blood to the
epidermis
hypodermis
(subcutaneous tissue) o Innermost layer of skin o Contains fibroblasts, adipose cells, and connective tissue o Insulates the body o Stores energy o Protects the inner organs o Connects skin to muscle
cellulitis
+ types
Cellulitis is an acute bacterial infection of the dermis and
subcutaneous tissue
o In more serious cases, the muscle can also be affected
• Bacteria usually enters the body through a skin break
o Cellulitis can affect normal skin too if bacteria enters
through pores or hair follicles
• There are different types of cellulitis which are designated
by the location of the infection
o Facial cellulitis – occurs on the facial tissues such as the
cheeks
o Orbital cellulitis – occurs in the eye and the structures in the orbit
o Periorbital cellulitis – occurs in the eyelid and tissues surrounding the eye
purulent or non purulent
Cellulitis can be purulent or non-purulent
o Cellulitis is considered purulent when there is
presence of a pustule or abscess
• A pustule is a patch of skin that is filled with pus
• An abscess is similar to a pustule, but is generally
larger and occurs deeper in the skin
cellulitis clinical presentation + symptoms
Cellulitis can occur anywhere on the body but is most common in the lower limbs, especially near the shins and ankles
• Cellulitis is rarely bilateral
• Presents as poorly demarcated erythema
• Skin redness does not have a well-defined border
• Purulent cellulitis will have exudate and presence of an abscess
• Symptoms
• Pain and swelling in the affected area
• Fever
• Chills
• Warm skin
diagnosis
There is no medical test that can diagnose cellulitis
• Diagnosis is mostly based on physical exam and
medical history
• Skin cultures rarely identify the correct bacteria that
is causing cellulitis, so they are usually not
recommend
Group A beta-hemolytic streptococcus causative agent
o Causes beta-hemolysis which is the complete lysis of red
blood cells that are in the vicinity of the bacterial colony
o Commonly found in the nose, throat, and on the skin
o More likely to cause non-purulent cellulitis
o Gram-positive
o The most common example is Streptococcus pyogenes
risk factors
Break in the skin
Lymphedema
•Lymph vessels are not able to drain lymph fluid
•Causes tissue swelling
•The body is not able to effectively fight infections
•Diabetes •Cancer •Autoimmune disease Obesity History of cellulitis
complications
necrotizing fascitis
- More serious infection of the subcutaneous
tissue
• Can lead to gangrene which is extensive tissue
damage and tissue death
• Can lead to sepsis
• About 25% of cases are fatal
sepsis
- Occurs when the body’s response to infection
gets out of control
• Infection enters the bloodstream (septicemia)
and triggers inflammation throughout the body
• Can lead to organ failure and death
biological process
After the entry of bacteria, cytokines and
neutrophils are recruited to the area which
initiates an inflammatory response and causes
the redness and swelling
• If the body’s immune response is absent or not
sufficient, the infection can spread to adjacent
tissues and the bloodstream
medical treatments
Penicillin-based antibiotics
o Structure of the bacterial cell wall
§ The major structural polymer is peptidoglycan
§ Through the enzyme DD-transpeptidase, a single
peptidoglycan chain can be cross linked to another
§ This process forms the rigid cell wall
o Penicillin contains a four membered beta-lactam ring
that binds to DD-transpeptidase
§ Inhibits the cross linking of peptidoglycan chains
§ Weakens the cell wall and causes bacterial cell death
o Can treat most cases of cellulitis
o 5-6 days of antibiotic therapy for uncomplicated cellulitis is usually sufficient
§ Many symptoms may disappear within 48 hours, but it is still important to finish the prescribed antibiotics
penicilin antibiotics with gram negativ e stuff
Penicillin-based antibiotics
o Effective for infections caused by gram-positive
bacteria due to the thick peptidoglycan layer in the cell wall
o Gram negative bacteria are more resistant to betalactams due to the presence of a lipopolysaccharide
layer which prevents the entry of antibiotics
non beta lactams
Other types of antibiotics (non-beta-lactams)
o Used to treat cellulitis caused by methicillin-resistant Staphylococcus aureus
(MRSA)
§ Treatment usually lasts 7-14 days
o Examples include clindamycin and tetracyclines
o Stop growth of bacteria
Abscess drainage
oUsed to treat purulent cellulitis
o Abscess is drained through a needle or by making an incision
Compression therapy
o Helps manage edema which is a predisposing condition
o Should not be done during active infection
o Can be used to prevent cellulitis from recurring
abscess
An abscess is a pocket of liquid called pus that collects
in tissues, organs, or spaces within the body.
• They occur when an area of the body is infected, causing
the body’s immune system to react.
• The immune system sends white blood cells to fight the infection. These cells combine with damaged and
infected cells in the body, forming liquid pus.
where can u get an abscess
Skin - when bacteria get under the surface of the
skin. Can occur anywhere in the body
• Common in the underarms, hands/feet,
genitals, and buttock
• Internal – Develops inside the abdomen. Caused by an infection reaching deeper tissues.
• Brain – a bacterial or fungal infection reaching
the brain, causing the collection of pus.
• Dental – bacterial infection that reaches the pulp of the tooth, resulting in an infection near the root of the tooth.
dental abscess
More specifically, a dental abscess is a pocket of pus that develops in the mouth. • They typically occur at the tip of a tooth root. This is called a periapical abscess. • This type of abscess typically occurs due to an untreated dental cavity that has reached the pulp of an infected tooth. • Can also occur due to an injury
symptoms
• Persistent throbbing in the area of the abscess • Sensitivity to hot and cold temperatures • Sensitivity to pressure • Fever • Swelling in your face and cheek • Foul-smelling/foul-tasting salty fluid
health risks of abscess
Potential infection that spreads from the abscess throughout the body • Blood poisoning • Tissue death surrounding the abscess • Methicillin-resistant Staphylococcus aureus (MRSA) infection • Strain of bacteria that is resistant to many antibiotic drugs
types of leukocytes
Five main leukocytes:
• Neutrophils – most common type of leukocyte and act as phagocytes in the innate immune system. Usually the first leukocyte at the site of an invasion.
• Lymphocytes – Include B cells, T cells, and Natural killer cells which are part of the adaptive immune system.
•Macrophages/monocytes – Phagocytes in the innate immune reactions. Monocytes are the immature form found in blood vessels and macrophages are the mature form found in the tissues.
• Eosinophils – contain granules that can be released to kill pathogens.
• Basophils – The least numerous leukocyte which contains granules with histamine (causes vasodilatation), and heparin (an anticoagulant).
innate immune response
The first line of defense which generates a nonspecific immune response
• Physical barriers of the innate immune system include the skin, cilia and mucous membranes
• Steps of the Inflammatory response:
1. Mast cells release histamine
2. Histamine dilates blood vessels and makes them more permeable to let in immune cells.
3. Phagocytes engulf pathogens and damaged cells
4. Basophils aid in engulfing foreign cells and release histamine, causing an inflammatory response.
5. Symptoms such as redness, fever and swelling typically occur
development of abcsess
Due to an opening or cut in the skin or mouth, bacterial cells enter the open wound and multiply.
• In response, the immune system initiates the inflammatory reaction of the innate immune system
• Call white blood cells to the site of injury and dilate blood vessels, bringing more blood to the area
• The first white blood cells that get to the scene are neutrophils
• Kill bacteria and dissolve dead cells
• Leads to suppurative inflammation: pus is created in the process
• Immune cells eventually die and join the pool of liquid pus
• A wall of fibrinogen eventually forms around the pus, creating a barrier. This leads to the formation of
the abscess
common bacteria species in abscess
Staphylococcus aureus – the most common in abscesses dealing with the skin. • Including methicillinresistant S. aureus (MRSA) • Gram - positive • Releases Coagulase – speeds up the process of fibrinogen wall formation.
diagnosis
Skin • Palpation • may feel the fluid moving around - fluctuance • Ultrasound • MRI scans • Teeth • Palpation • Percussion • Identifies sensitivity • Periapical X-ray
treatments
Apply warm compressions to the infected area
for about 30 minutes, 4x a day
• Have a dentist incise and drain the abscess
• Allows the puss to drain out
• Wash the area with saline solution after the incision
• Perform a root canal on the infected tooth
• May eliminate the infection while still saving the
tooth
• Pull the infected tooth
• Incision is made to drain the abscess after the
extraction
• Prescribe antibiotics
• Recommended if the infection has spread to
other parts of the body or if the patient has a
weakened immune system.
• Helps ensure any living bacteria is eliminated
Antibiotics
Penicillin based antibiotics
• contains a four membered beta-lactam ring that binds to DDtranspeptidase, which is the enzyme that links peptidoglycan chains
• Ultimately inhibits the linking of peptidoglycan chains and destroys
the cell wall
• Highly effective against gram-positive bacteria because of the think
peptidoglycan layer in the cell wall
• Not very effective against gram-negative bacteria due to the
lipopolysaccharide layer.
Staphylococcus aureus
including methicillin-resistant S. aureus (MRSA)
o More likely to cause abscesses
o Gram-positive
• Gram-negative bacteria are less likely to cause cellulitis
