Microbiology an Introduction: Microbiology Chapter 22 Flashcards
Inflammation of the meninges
Inflammation of the brain
Which is more common and mild, bacterial meningitis or viral meningitis?
What types of pathogens can cause meningitis?
Viruses, bacteria, fungi, and protozoa.
What organisms can cause meningitis and convulsions?
Haemophilus influenzae, Neisseria meningitidis, Streptococcus pneumoniae, Listeria monocytogenes.
Why are bacterial encephalitis and meningitis difficult to treat?
Many antibiotics cannot penetrate the blood-brain barrier.
What organism causes Tetanus?
Gram-positive, endospore-forming, obligate anaerobe.
The symptoms of tetanus are caused by which neurotoxin?
How does tetanospasmin work?
It is released from dead cells. It enters the CNS. It then blocks the relaxation pathway in muscles, causing muscle spasms.
How does death occur with tetanus?
From spasms of respiratory muscles.
What are some symptoms of tetanus?
Lockjaw, stiffness of neck muscles, difficulty swallowing, painful body spasms.
What organism causes botulism?
Gram-positive, endospore-forming, obligate anaerobe.
What does the botulinal exotoxin do?
Since it is specific for the synaptic end of the nerve, it blocks the release of the neurotransmitter acetylcholine, causing flaccid paralysis.
How does death usually occur with botulism?
Respiratory or cardiac failure.
What are some common symptoms of botulism?
Nausea, double or blurred vision, difficulty swallowing, general weakness.
What is poliomyelitis and what is it caused from?
Polio, caused by the poliovirus.
How is it transmitted and what are the initial symptoms?
Transmitted by the ingestion of water containing feces containing the virus.
Sore throat and nausea.
If viremia occurs with Polio, what happens?
The virus enters the CNS where it targets and destroys motor cells.
How does death normally occur from Polio?
What are the two vaccines for Polio?
Salk and Sabin vaccine.
Which vaccine contains the inactive virus and how is it administered?
Salk vaccine; injectable.
Which vaccine is more effective?
Sabin vaccine which is thought to give lifelong immunity.
Which disease almost always results in fatal encephalitis?
What is the causative agent of rabies?
Rabies virus, from the genus Lyssavirus.
What shape is the Lyssavirus?
What are some characteristics of the Lyssavirus?
Single-stranded RNA; easily develops mutants.
How is rabies virus normally transmitted?
By the saliva or an animal bite.
It can also cross mucous membranes.
What are the most common cause of rabies in the United States?
What is unique about the incubation time of rabies?
It is usually long enough to allow immunity to develop from postexposure vaccination.
Why is the natural immune response ineffective against rabies?
The viruses are introduced into the wound in numbers too low to provoke it; also, they do not travel through the bloodstream or lymphatic system, where the immune system could best respond.
What are the initial symptoms of rabies?
Muscle spasms of the mouth and pharynx; hydrophobia.
When the rabies virus enters through the PNS to the brain cells, what does it cause?
What is the average incubation period for rabies?
30 to 50 days.
How is rabies diagnosed?
In the laboratory by detection of the viral antigen using the direct fluorescent-antibody test.
Who is routinely vaccinated against rabies?
High-risk individuals, such as lab workers, animal control professionals, and veterinarians.
If a person is bitten and the animal is tested positive for rabies, what does the person undergo?
Postexposure prophylaxis (PEP), the vaccine plus immune globulin injections.
Once the symptoms of rabies appear, which is the most effective treatment?
There is very little by way of effective treatment and only a handful of survivors have been reported.
Where does rabies occur?
All over the world, mostly as a result of dog bites.
How many cases of rabies occur in the United States annually?
1 to 6
What are arboviruses and what are they caused by?
Arthropod-borne viruses, caused by mosquito-borne viruses.
What diseases are caused by arboviruses?
Eastern equine encephalitis (EEE), Western equine encephalitis (WEE), St. Louis encephalitis (SLE), California encephalitis (CE), West Nile virus (WNV), Japanese encephalitis.
When are arboviruses more common?
During summer months.
What is the most effective preventative measure against arboviruses?
Local control of mosquitoes.
What does Naegleria fowleri cause?
Primary amebic meningoencephalitis (PAM)
What does N. fowleri infect?
The nasal mucosa and then it penetrates the brain and feeds on brain tissue.
Who usually contacts N. fowleri?
Children who swim in warm ponds or streams.
What is the fatality rate of N. fowleri?
Nearly 100% fatal.
What diseases are caused by prions?
Sheep scrapie, chronic wasting disease, Creutzfeldt-Jakob disease, Kuru, Bovine spongiform encephalopathy (mad cow disease).
What is Chronic Fatigue Syndrome?
Unexplained fatigue that lasts at least 6 months plus other flulike symptoms.
Also called myalgic encephalomyelitis (ME), it is linked to the immune system and possible genetic components.
What may trigger Chronic Fatigue Syndrome?
How many people are affected by CFS?
.52% of women and .29% of men.
What is the approved treatment for CFS?
None, but there is an experimental drug.