Internal Tissues

Infections of Internal Tissues
Chapter 30
Microbiology for Surgical Technologists
Breast Tissue
Infections of the breast are termed mastitis
It can be generalized or localized
Typically associated mostly in lactating mothers
Pregnancy, lactation and breastfeeding are the indications for infection
Lactational mastitis
Occurs with breastfeeding
It is a generalized infection of the breast
Nipples tend to chafe and crack from breastfeeding
Bacteria from the babies mouth enter the milk ducts through the cracks
What kind of bacteria?
Women who choose not to breast feed have to let the milk ducts reabsorb the colostrum
This makes the breasts hard, hot and painful
Milk ducts can clog and if microbes are present infection can occur
Including abscesses that need to be corrected with an I&D
Lactational mastitis (continued)
Warm compresses, massage, and antibiotics are used to unblock the duct and relieve the infection
Some cases will require surgical I&D
Nonlactational Mastitis
Usually a localized infection associated with cellulitis, folliculitis, or other skin infection
Can occur following breast bx (lumpectomy)
Treatment is the same as for lactational mastitis
Chronic Subareolar Abscess
Occurs when sebaceous glands around the nipple become infected
Pus and fluid accumulate
Treatment involves surgical I&D
Fascia and Tendons
Infection of the fascia is called fasciitis
Tendonitis is an infection of tendons, the tissue that connects muscles to bone
Bacterial infections of the tendon itself are very rare
Infections usually involve the covering called the tendon sheath
Infections of the tendon sheath, tenosynovitis
Usually the result of a traumatic injury
The infection can travel along the tendon sheath compromising the tendon and causing necrosis
Bone and Joint Infections
Infections of the bone are called osteomyelitis
Primary infections in children usually occur at the growth point of the long bones
Primary infections in adults is usually from traumatic injury
Chronic infections often are a secondary infection from a pulmonary infection
Septic arthritis is from bacterial invasion of the joint either from the bloodstream or traumatic injury
The usual culprit is S. aureus
Usually only involves one joint
Rare infections from gonorrhea cause infections in multiple joints called polyarthritis
Lymph Nodes
Lymph nodes are specialized tissues that filter bacteria, viruses and other abnormal cells from the body
The nodes can be overwhelmed by invading microbes and cancer cells causing sepsis or metastasis (?)
Lymphadenitis is the inflammation of the lymph node
Can affect a single node or group of nodes
Lymphangitis, inflammation of the lymphatic vessels, is a sign of septicemia
Is characterized by red steaks running along under the skin from the site of infection toward the heart
Lymphatic System
Septicemia
Surgical Implications
The ST can introduce bacteria into internal tissues very easily, resulting in serous infections.
It can be deadly for immunocomprimised pts
Strict aseptic principles must be applied by the ST for every procedure
Lymph node bx is a common procedure and is used to indicate metastasis from a primary cancer site to other parts of the body, or to diagnose other diseases
It is the ST’s responsibility to obtain the exact location that the specimen was taken from and keep multiple specimens separate
As the specimen is passed to the circulator, the ST informs them as to the location that the specimen is from
If the information is incorrect, it could have serious consequences to the pts treatment
If the specimen is to go for frozen section it should be kept moist, but not immersed in liquid, and placed on some sort of material that can be passed off the field
Usually a telfa
Never use a counted sponge
Introduction to Viruses
Chapter 31
Microbiology for Surgical Technologists
Characteristics of Viruses
Viruses are distinguished from other living cells by the following characteristics:
Replication of the virus is directed by the host cell, they do not replicate by binary fission or mitosis
Contain either DNA or RNA, never both
Do not have the enzymes needed to produce energy, depend on protein production of the host cell
Viruses are intracellular parasites
The genetic component (RNA or DNA) is surrounded and protected by a protein covering called a capsid
The individual protein molecules of the capsid are called capsomere
The capsid has components for attachment to the host cell
Some viral particles (virions) have a nucleocapsid surrounded by an outer membrane borrowed from the host cell membrane, this is called an envelope
Infection by Viruses
Viruses can enter the body by respiratory droplets, through an exchange of body fluid, ingestion of contaminated food or water, or by bites from vectors
The virus first attach themselves to the host cell with the aid of receptors on the capsomere
They then enter the cell either by direct penetration of the cytoplasmic membrane or through receptor-mediated endocytosis
The nucleic acid is then uncovered and viral replication begins
The Infectious Process of a Rhinovirus
The Common Cold
An infected person sneezes in an area near you, ejecting thousands of viral particles into the air
You inhale some of the virus particles
The virus binds to the cells lining your nasal sinuses
They then replicate within the cell
The host cells lyse and new viral particles begin to move into your lungs
The virus triggers your infected sinus cells to release fluid that flows into your throat.
The virus in the fluid attack the cells lining your throat, making it sore
Your immune system kicks in to fight the infection, releasing pyrogens that cause your body temp to rise
The rise in temp slows the rate of viral replication
Your symptoms start to deminish and you slowly start to get well
A cold is self limiting and will go away on it’s own
Question:
Can you use antibiotics to stop a virus?
They are only used to stop bacterial infections
Lysogenic and Lytic Cycles
Once inside the host cell, some viruses, such as herpes or HIV, do not reproduce right away
After infecting the host cell, they mix their genetic material and instructions for replication into the host cell’s genetic material
When the host cell reproduces, the viral genetic instructions get copied into the host’s daughter cell
This latent period continues until some environmental or predetermined genetic signal causes the viruses to begin rapid replication and to begin infecting other cells
This is the lysogenic cycle

When the genetic material of the virus takes over the metabolic machinery of the host cell and begins producing virions, it has entered the lytic cycle
The virion releases its genetic instructions into the host cell’s genetic instructions and has the cell’s enzymes construct new virus particles

The host cell then lyses releasing the virus particles to infect other cells
Sometimes the virions are released from the host cell in a budding process
Capsids are formed as they pass through the cytoplasmic membrane of the host cell
Hep B is released this way
Viruses can sometimes disrupt a host cell to the point of transforming it into a malignant cell
The cells become invasive and develop into tumors
Example: Hep C can cause liver cancer
Interferons
INFs are glycoproteins that interrupt replication of viruses
They are produced by the host cell as a defense mechanism
Humans produce two types
Type I
TypeII
Type I – produced by:
Leukocytes (INF α)
Fibroblasts (INF β)
Type II – produced by:
Lymphocytes (INF γ)
Bacteriophages
They are viruses that invade bacteria and are called complex viruses
They connect to the bacterial host by either binding to a receptor site on the cell wall or to its fimbriae or flagella
They have a capsid with additional structures attached
Latent Infections
Some viruses remain in the host for a lifetime and emerge sporadically when conditions are right, these are called latent infections
Herpes Simplex virus is an example
Lives in the nerve cells
Produce cold sores
Heat, ultraviolet rays, or stress can reactivate the virus and cause recurrence of the disease
Antibiotics are ineffective against viruses
They may be given to a pt that has a secondary bacterial infection
Research has primarily focused on prevention using vaccination
Because of rapid mutation of viruses, many vaccines are updated each year
Surgical Implications
The ST is often exposed to viruses such as Hep B and HIV in the OR
Pts are not required, in fact it is against the law, to pre-screen for these diseases
Universal Precautions should be used on all pts
Words of Wisdom
Life is not easy for any of us. But what of that? We must have perseverance and above all self confidence in ourselves. We must believe that we are gifted for something, and that this thing, at whatever cost, must be attained.
Marie Curie
(1867 – 1934)