Respiratory System
Chapter 25
Microbiology for Surgical Technologists
Respiratory Tract
Is a common site for infection due to exposure to airborne pathogens
The upper tract is populated with indigenous microflora, but the lower tract is considered sterile
Diseases may be viral, bacterial, or fungal and may be mild to life threatening
Anatomy Review
Anatomy
Takes in oxygen and expels carbon dioxide
Divided into upper and lower tracts
Upper tract: nose and sinuses, pharynx (naso, oro, and laryngeal), middle ear and eustachian tubes
Lower tract: Larynx (voice box), trachea, bronchial tubes, and alveoli
As air enters the nose and pharynx, it passes the epiglottis (a small piece of cartilage that covers the larynx), the larynx and moves into the trachea
The trachea is a cylindrical pipe composed of smooth muscle with C-shaped rings of cartilage
It divides into the right and left bronchi
The bronchi divide again into bronchioles
The bronchioles terminate into alveolar ducts
Around each duct are round structures called alveoli
The alveoli are responsible for transferring oxygen from the alveolar ducts to the blood in exchange for carbon dioxide
When particles and microorganisms enter the lower respiratory tract are trapped in mucus produced by goblet cells
They are moved upward for expulsion by cilia
Upper Respiratory Tract
The normal flora of the URT contain potentially pathogenic microorganisms that are kept in check by the friendly ones that compete with the opportunistic pathogens for growth resources in the environment
Normal flora consists of Staphylococcus, Streptococcus, Haemophilus, Micrococcus, and Veillonella species.
Some spirochetes and viruses are also present
Infections of the URT are pharyngitis, laryngitis, sinusitis, and tonsillitis
They tend to be bacterial or viral, and less often fungal
Sinuses tend to be infected with S. Pneumoniae or Haemophilus influenzae
Bacterial infections tend to be Streptococcus pyogenes (strep throat)
Otitis Media is commonly caused by Streptococcus pneumoniae
Causes pus to build up and compress the tympanic membrane
Lower Respiratory Tract
Tuberculosis is caused by Mycobacterium tuberculosis
Diptheria is caused by Corynebacterium diphtheriae
Viral Infections
The Common Cold
About half of all colds are caused by the rhinovirus
The rhinovirus has 113 strains, rendering a vaccine impractical
Another 15% to 20% are caused by the coronavirus
We get fewer colds as we age due to our mature immune systems
It is spread by aerosol droplets from sneezing
The virus is also on the hands of the infected person and can spread to others during physical contact
The virus takes hold of the host cells or cilia
This prevents them from being washed away by the secretions that they trigger
If the infection reaches the middle ear, it will cause Otitis media
If the infection invades the sinuses from the pharynx, it will cause sinusitis
Common fallacies of the common cold
It is not produced by cold weather, the weather causes people to stay indoors where transmission is more likely
Antibiotics do not kill viruses and are of no use unless the pt acquires a secondary bacterial infection
How to tell the difference
Influenza
Commonly called the “flu”
Is a common illness but it can be dangerous
Symptoms include: fever, chills, cough, headache, and muscular pains
As many as 20,000 Americans die each year from the flu
Viral Infections (continued)
There are three types of influenza
A – responsible for epidemics and are transmitted through animals, usually birds
B – cause epidemics but are never transmitted through animals
C – only cause minor respiratory illnesses and never epidemics
Transmission is by aerosol droplets
Bacteria attach to epithelial cells
Within three days, cytokines expel from damaged cells and leukocytes cause fever and muscle aches
Most people recover in a few days
Secondary Staphylococcus aureus infections can be a dangerous aspect
There is no cure for the flu
There is a yearly vaccine produced for the strain most likely to occur
Experts don’t know for sure which stain will be predominant, so they take a calculated chance on the recommended vaccine
Fungal Infections of the Respiratory Tract
Fungal infections are acquired by breathing in the airborne spores
Histoplasmosis is a fungal disease that resembles TB
It is caused by Histoplasma capsulatum
Transmitted by bird and bat droppings
Coccidioidomycosis is caused by Coccidioides immitis
A pulmonary fungal disease endemic in the American Southwest and northern Mexico
The spores from the soil are carries on the wind
Symptoms resemble TB
Blastomycosis is caused by Blastomyces dermatitidis
Seen primarily in the Mississippi Valley
Most infections are asymptomatic, some deaths do occur
The pulmonary infection spreads to the skin causing cutaneous ulcers
Pneumonia
An acute infection of the lung tissues and alveolar spaces
Pathogens can be bacteria, fungi, protozoa, and viruses
Is often a secondary bacterial infection from a primary viral infection
Symptoms include fever, cough, acute chest pain, and respiratory distress
Bacterial pneumonia is most often caused by Streptococcus pneumoniae
It forms cells in pairs that prevent phagocytosis
This type of pneumonia is called pneumococcal pneumonia
Pts often develop pleurisy (inflammation of the pleura)
This type of pneumonia causes many deaths of elderly pts
Pts who do not have secondary infection, and are not compromised will recover with the use of antibiotics and their own immune system
Approx 6 – 10 days into the illness the pt heavily sweats and the fever is “broken”. This happens at the same time as an anticapsular antibody appears
The anticapsular antibody serves as a bridge between the bacteria and phagocyte, it aids in phagocytosis
The phagocytes then eliminate the pneumococci and the macrophages migrate to the lung to clear away any debris
This type of pneumonia usually does not cause permanent damage, if the pt recovers, unlike other types of pneumonia
The spleen also plays a role in the recovery process
It filters the pneumococci from the blood, and produces a type specific antibody to destroy them
People that have had a spleenectomy are susceptible to pneumococcal sepsis
Pneumococcal Sepsis
The following is an actual case that happened at Seton Northwest in March of 2005
The patient is a 39 yr old male that had a previous spleenectomy
He acquired a pneumococcal infection and because he could not fight the disease, (because of the previous spleenectomy) he became septic and this is what happened
Pneumococcal Sepsis
He became septic
What does that mean?
The infection attacked the peripheral sections of his body
What does that mean?
Pneumococcal Sepsis
The infection lodged in his left hand causing necrosis of the fingers
Notice the advancement of the infection up the arm
Pneumococcal Sepsis
This is a closer view of the hand
The fingers are contracted due to the infection and necrosis of the digits
Pneumococcal Sepsis
In this picture you can see the some of the damage to his toes
Pneumococcal Sepsis
This is a closer view of the left foot
The toes look as if they have been mummified
The line across the foot are the markings from the surgeon, with a skin marker, for the incision
Pneumococcal Sepsis
This demonstrates the infection of his nose
It shows the necrosis on the bridge and tip
Not shown is the auricular portion of the ear that is missing
Pneumococcal Sepsis
This demonstrates the incision made into the foot in order to amputate
They began with a 10 blade and continued with the bovie as shown
Pneumonia (continued)
Mycoplasmal pneumonia is caused by Mycoplasma pneumoniae
It does not have a cell wall
It is called “walking pneumonia” because of the mild symptoms it causes
Sometimes will be mistaken for a viral infection
Eye, Ear, Nose, and Throat
Chapter 26
Microbiology for Surgical Technologists
Anatomy of the Eye
The most complicated of the sensory organs
It is a hollow globe made up of three layers of tissue
The sclera is the outermost layer and is continuous with the
Cornea, the clear transparent anterior covering of the eye
The choroid is the inner layer of the sclera
Other parts of the eye are
The ciliary body, which consists of smooth muscles that hold the
Biconvex transparent lens in place
The pupil is the clear opening over the lens
The iris is the colored part of the eye that surrounds the pupil and regulates the amount of light the enters
The retina is the innermost layer that contains light sensitive cells called rods and cones
The interior of the eye is divided into two chambers
The anterior chamber is in front of the eye under the cornea
Contains a fluid called aqueous humor
The posterior chamber, the inside of the globe contains vitreous humor
It helps to maintain intraocular pressure and refract light
The accessory organs of the eye include:
The eyelids with lashes
The conjunctiva, which covers the inner surface of the the eyelids
The lacrimal gland which secretes lubricating tears
Tears are drained from the eye by the nasolacrimal duct into the nose
That is why your nose runs when you cry
Anatomy of the Ear
Used for hearing and to maintain equilibrium (balance)
The external ear is the visible portion outside of the ear, ear canal to the external portion of the tympanic membrane (ear drum)
The middle ear is an air-filled cavity responsible for amplifying the sound waves from the eardrum
It contains three auditory ossicles (bones)
The malleus (hammer)
The incus (anvil)
Stapes (stirrup)
It also contains the Eustachian tube
The malleus is connected to the inner surface of the tympanic membrane and transmits sound waves to the other two ossicles
The stapes is in contact with the oval window that connect the middle ear to the inner ear
The inner ear contains
The cochlea, which handles hearing
The vestibule and the semicircular canals, which handle balance
Anatomy of the Nose
The outer portion is composed of cartilage and bone covered by skin
The inner portion is lined with mucous membranes that keep air moist as it enters
The two openings are called external nares (nostrils)
It is divided into left and right by the nasal septum
The area just inside the nose is called the vestibules
There are four sinuses that empty into the nasal cavity; frontal, maxillary, sphenoid and ethmoid
The pharynx is divided into three parts
The nasopharynx is the uppermost part, contains the pharyngeal tonsils (adenoids)
Oropharynx, the common path for food and air contains the lingual tonsils
Layrgopharynx connects with the esophagus and larynx
Anatomy of the Nose (continued)
EENT Microbial Diseases
Otitis media
“Swimmer’s ear” is a painful pseudomonal infection of the external canal
Conjunctivitis (pink eye) is an infalmmation of the conjunctiva
Can spread to the lacrimal glands (dacryocystitis) and to the eyelids (blepharitis)
EENT Microbial Diseases (continued)
EENT Microbial Diseases (continued)
Sinusitis is an infection of the sinuses
Sinuses become inflamed and a heavy discharge of mucous ensues
Usually a dark yellow or green mucous in bacterial infections
Can be treated with antibiotics and may need I&D
Can spread to the brain
Surgical Implications
Myringotomy for Otitis media
Tonsillectomy and adnoidectomy (T&A)
Sinus irrigation
Sinusoscopy
Craniotomy for I&D of infection
Having once decided to achieve a certain task, achieve it at all costs of tedium and distaste. The gain of self-confidence of having accomplished a tiresome labor is immense.
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