CSF & Blood

Pathogens of Body fluids
Microbiology for the Surgical Technologist
Chapter 23
Central Nervous System
CNS
Anatomy of the Spinal Cord
Three protective membranes cover the brain and the spinal cord called the meninges.
The thickest outer layer called the dura mater.
The middle layer that looks like a cobweb is called the arachnoid mater.
The innermost layer called the pia mater.
Cerebrospinal fluid
Also known as the CNF
Is located in the subarachnoid space
Infections of the CNS
An infection or inflammation of the meninges is called meningitis
Inflammation of the brain parenchyma is called encephalitis
What is the parenchyma of an organ?
Then there are brain abscesses
What is an abscess?
The majority of CNS infections are viral,
But can be caused by bacteria, fungi, parasites, etc.
To diagnose a CNS infection fluid is drawn through a lumbar puncture
What is this known as?
Most infections enter through the bloodstream by way of a penetrating wound or surgical procedure
Or abscesses can spread from the sinuses and infect the CNS
Bacterial Meningitis
Acute bacterial meningitis is an infection of the pia and arachnoid layers
It is life threatening and requires immediate medical treatment
Primary agents are
Haemophilus influenzae
Streptococcus pneumoniae
Neisseria miningitidis
These are normal flora of the nose and upper respiratory system and often infect the CNS when the immune system is distressed
Can also occur as a complication of other diseases such as
Endocarditis
Pneumonia
Otis media (middle ear infection)
Occurs most frequently in small children
Ages 1 month to 2 years
Symptoms include
Headache, stiff neck, sore throat
People will sometimes misdiagnose themselves as having just a cold
Treatment includes intravenous antibiotics
Outbreaks can occur where groups of people reside
College dormitories, military camps, communes
Vaccines
N. meningitidis is used mainly during epidemics
H. influenzae type B
This is a required vaccine in US
Given to all children over 2
Has reduced the incidence of this type of meningitis by 95%
Chronic Meningitis
Certain fungal infections, especially Cryptococcus, develop slowly and can result in chronic meningitis
Cytomegalovirus and AIDS can cause it
Some cancers, the drugs to treat cancer and to prevent tissue rejection can cause this disease
Treatment depends on the causative agent
Viral Meningitis
Not as dangerous and occurs more frequently than bacterial meningitis
It is seasonal
Spring – begins as mumps
Summer and early fall – begins as enteroviruses
Winter – lymphocytic choriomeningitis
From mice that move indoors in the winter months
Major agents are enteroviruses
Mumps, herpes simplex type I, HIV, and arboviruses
Arboviruses are transmitted by ticks and mosquitoes
Recovery takes weeks
No mortality
Pts don’t die unless there are secondary infections and the pt is immuno-comprimised
Brain Abscess
Usually found within the frontal or temporal lobe of the cerebrum
Pus may be encapsulated or free flowing
Causes subdural empyema – collection of pus just beneath the dura of the brain
It is usually secondary to an infection in another area of the body
Otitis media, sinusitis, mastoiditis, tooth infection, etc.
Encephalitis
Inflammation of the brain parenchyma
More dangerous than viral meningitis
Herpes simplex encephalitis is the most common type in the US
If untreated fatality rate is 70%
Treated with Acyclovir
And other anti-viral agents
Very effective if administered early in the infection
Rabies
More of a problem in canine populations of developing countries
A problem in wild animals in US
Including skunk, fox, raccoon, and bats
Transmitted to humans through bites by infected animal
If the vaccination is not administered before clinical symptoms manifest, death is imminent
Prions
Prion are “proteinaceous infectious particles”
Prion diseases are subacute spongiform encephalopathies
Caused by a protein that acts as an infectious agent
Literally punches holes in the brain tissue
First though to be viruses they lacked RNA and DNA
Consist mostly of protein
Can be inherited or transmitted communicably
Through contaminated instruments or the injection of human growth hormone derived from the pituitary gland of cadavers
About 10% of human prion disease is familial (inherited), while the other 90% is contracted
Most common form in animals is “scrapie”
Found in sheep and goats
Develop an unbearable itch that causes them to “scrape” off their coat
Animal develops ataxia (loss of all motor control)
Eventually unable to stand
Transferred to cows (mad cow disease) through food supplements that are made from meat and bone meal from dead sheep
Human prion disease has been traced to tribal natives of Papua New Guinea
Called the “laughing death”
Causes ataxia, dementia, and eventual death
The disease was caught from eating human brains
A sign of respect for the dead in their culture
Once the practice was stopped the disease was eradicated
They cannot be destroyed by conventional sterilization methods
Instruments known to be contaminated must be destroyed
* There are new technologies that can kill Prions that have been developed to destroy the pathogens
It has been discovered that just raising the temperature and extending the time in autoclaves the prion can be killed
Parasitic Infections
Acute infections
Typically caused by free-swimming amoebas and trichinosis
Result in meningitis or encephalitis
Chronic infections
African trypanosomiasis (sleeping sickness)
Caused by Schistosoma japonicum
Creates cerebral granulomas
Chronic infections (continued)
Chronic parasitic encephalopathies
Caused by Toxoplasma gondii
Creates brain abscesses
Cysticercosis
Most common of the parasites
Caused from the larvae form of Taenia solium
Pathology includes arachnoiditis and parasitic cysts
Result in seizures and hydrocephalus
Cysticercosis
Other Body Fluids
Amniotic
Pericardial
Pleural
Peritoneal
Synovial
Blood
Amniotic Fluid
The fluid found within the amniotic sac
Outer layer of amniotic sac is the amnion
Inner layer of the amniotic sac is the Chorion
Amnionitis
An infection of the amnion
Can result from prolonged labor, premature rupture of membranes, cervical cerclage, amniocenteses
Chorioamnionitis
Infection of the chorion and amniotic fluid
Pericardial Fluid
Fluid contained within the pericardial sac that surrounds the heart, the infection is called pericarditis
Endocarditis
Inflammation of the endocardium, the layer that lines the heart muscle and covers the heart valves
Two types:
Subacute bacterial endocarditis – slow to develop
Acute bacterial endocarditis – sudden onset
Subacute bacterial endocarditis
Usually caused by hemolytic streptococci
Typically found in the oral cavity
Result from infections of the teeth or tonsils and other parts of the body
Acute bacterial endocarditis
Typically caused by Staphylococcus aureus
Cause damage to the heart valves and results in death if untreated
Pericarditis
Inflammation of the pericardium (heart sac)
Typically secondary to other infections in the body
Example: lung abscess, pnuenomia
Can be caused by a post surgical wound infection from another site
Mostly caused by streptococci
Nonspecific pericarditis
Caused by viral infections
Chronic pericarditis
Causes the pericardium to adhere to the heart
The origin is usually unknown
Surgery may be required to take down the adhesions
Pleural Fluid
Fluid found in the plural space (lungs)
If the fluid is purulent it is known as empyema
Pleurisy – the inflammation of the pleura
Can result from infection, trauma, or tumor
Typically the complication of respiratory disease

Peritoneal Fluid
The fluid in the peritoneum
Inflammation of the peritoneum is peritonitis
Acute peritonitis can result from spillage from GI tract, biliary tract, ruptured cysts or trauma
Synovial Fluid
Synovial fluid is the viscous fluid that is secreted by the synovial membrane within joint cavities, bursae and tendon sheaths
Non inflammatory disease includes:
Osteoarthritis and traumatic arthritis
Inflammatory disease includes:
Rheumatoid arthritis, gout
Septic Arthritis
Typically bacterial in origin
Blood
Bacteremia – the presence of bacteria in the bloodstream
Most cases caused by
Staphylococcus aureus – from the respiratory tract
coagulase negative staphylococci – from the geniturinary tract
Escherichia coli – from the intestinal tract
Septicemia - when bacteria enter the bloodstream and multiply faster than the immune system can destroy them.
Serology
The study of blood serum and the immune responses within the serum
Serum
The liquid that is left after the fibrogen and blood cells are removed
Serology
Can determine if the blood contains antibodies or antigens

Slide agglutination test
Bacteria are mixed with an antiserum
If the bacteria agglutinate (clump) in the antiserum it is a positive result
Enzyme-linked immunosorbent assay (ELISA) test
Used to identify lyme disease, also to identify AIDS
Western blot test
Can identify bacterium within serum
Protein is blotted onto filter
Dye tagged antibodies are washed over the filter
Positive test indicated by a colored band left on filter
Serology procedures can be used to :
Diagnose diseases, determine blood type, select blood for transfusion, type tissue for potential transplantation, detect allergy, detect hypersensitivity
Reminder
Students must provide documentation as to having a physical examination stating that they have the ability to perform their job duties as a Surgical Technician, TB test, Tetanus vaccine, and have started the HBV immunization series by midterm of the course.
Homework
Case study 2
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Questions for further study
All
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