Microbiology Chapter 17

What are the two main components of the nervous system?

Central nervous system (CNS) and Peripheral nervous system (PNS)

What are the three important functions of the nervous system?

Sensory, integrative, and motor functions

What is the role of cerebrospinal fluid (CSF)?

Provides nutrition to the CNS and acts as a liquid cushion for the brain and spinal cord

What is the blood-brain barrier?

A vascular interface that restricts most microorganisms and antibiotics from entering the nervous system

What is meant by the CNS being 'immunologically privileged'?

The CNS can only mount a partial immune response to immunologic challenges

What is the significance of microglia and brain macrophages?

They have phagocytic capabilities but are less active than phagocytic cells in other body parts

Is there normal biota in the CNS or PNS?

No, finding microorganisms in these tissues indicates a deviation from a healthy state

What are the common symptoms of meningitis?

Severe headache, painful or stiff neck, fever, nausea, vomiting, photophobia, and possible skin rashes

What is the most serious form of acute meningitis caused by?

Bacteria, particularly Neisseria meningitidis

How does Neisseria meningitidis enter the body?

Via the upper respiratory tract, moving into the blood and penetrating the meninges

What are the signs and symptoms of Neisseria meningitidis infection?

Sudden onset of fever, sore throat, chills, delirium, widespread bleeding under the skin, shock, and coma

What is the primary method for diagnosing meningitis?

Lumbar puncture (spinal tap) and analysis of cerebrospinal fluid

What is the treatment for suspected bacterial meningitis?

Immediate broad-spectrum antibiotics are administered

What is the common causative agent of community-acquired meningitis?

Streptococcus pneumoniae

What is the role of the polysaccharide capsule in Streptococcus pneumoniae?

It protects the bacterium against phagocytosis

What vaccines are available for Streptococcus pneumoniae?

Prevnar for children and Pneumovax for adults

What is aseptic meningitis?

A type of meningitis where no bacteria or fungi are found in the CSF, typically caused by viruses

What is the typical treatment for pneumococcal meningitis?

Initial treatment with vancomycin and ceftriaxone, switching to penicillin if sensitive

What is the significance of the subarachnoid space?

It is filled with cerebrospinal fluid, providing cushioning for the brain and spinal cord

What are ganglia in the peripheral nervous system?

Swelling in the nerve where cell bodies of neurons aggregate

What can cause the entrance of bacteria into the CNS?

Coinfection or previous infection with respiratory viruses

What is the mortality rate for treated meningococcemia?

15%

What are the highest risk groups for Neisseria meningitidis infection?

Young children, older children, and young adults

What is the role of neurotransmitters in the nervous system?

They are released from one neuron and act on the next neuron across a synapse

What is the function of the dura mater?

It is the outermost layer of the meninges that protects the brain and spinal cord

What are the symptoms of increased lymphocytes in the CSF?

Indicates infection or inflammation, commonly seen in meningitis

What is the relationship between the gut microbiome and the nervous system?

The gut microbiome influences brain development, blood-brain barrier integrity, and peripheral nerve construction

What is the primary causative agent of viral meningitis?

Enteroviruses, accounting for 90% of cases.

How does viral meningitis generally compare to bacterial or fungal meningitis?

Viral meningitis is generally milder and usually resolves within 2 weeks.

What is the mortality rate associated with viral meningitis?

Less than 1%.

What diagnostic method confirms viral meningitis?

Diagnosis is confirmed by viral culture or specific antigen tests after failure to find bacteria, fungi, or protozoa in the CSF.

What is the primary disease associated with the Zika virus?

Zika Virus Disease, which can cause microcephaly in babies.

What are common symptoms of Zika virus infection in adults?

Symptoms range from none to skin rash, conjunctivitis, and muscle and joint pain.

What serious condition can Zika virus trigger in adults?

Guillain-Barré syndrome, which can lead to paralysis.

How is Zika virus primarily transmitted?

By the bite of the Aedes mosquito, sexual intercourse, and vertically in utero.

What is the current status of Zika virus vaccination?

No vaccine is currently available, though dozens of candidates have been proposed.

What is poliomyelitis commonly known as?

Infantile paralysis.

What are the initial symptoms of poliomyelitis?

Short-term mild viremia with fever, headache, nausea, sore throat, and myalgia.

What can occur if viremia persists in poliomyelitis?

The virus can invade the CNS, leading to paralysis.

What is the causative agent of poliomyelitis?

Poliovirus, a nonenveloped RNA virus from the Picornaviridae family.

How is poliovirus transmitted?

Through the oral-fecal route via contaminated food, water, and surfaces.

What is the primary prevention method for poliomyelitis?

Vaccination, typically starting at 2 months of age.

What are the two forms of poliovirus vaccine?

Inactivated poliovirus vaccine (IPV) and oral poliovirus vaccine (OPV).

What is Naegleria fowleri commonly referred to as?

The 'brain-eating amoeba.'

How does Naegleria fowleri infect humans?

It burrows into the nasal mucosa after being forced into the nose while swimming.

What is the typical outcome of Naegleria fowleri infection?

Massive destruction of brain tissue leading to hemorrhage and coma, often resulting in death within a week.

What is granulomatous amoebic meningoencephalitis (GAM) caused by?

Acanthamoeba.

What are common symptoms of acute encephalitis?

Behavior changes, confusion, decreased consciousness, seizures, and symptoms of meningitis.

What is the primary treatment for herpesvirus encephalitis?

Empiric treatment with acyclovir.

What are arboviruses?

Viruses transmitted by arthropod vectors, often causing acute fever and encephalitis.

What is a characteristic of subacute encephalitis?

Symptoms take longer to appear and are less striking than acute encephalitis.

What organism can cause subacute sclerosing panencephalitis?

Persistent measles virus.

What can prions cause in the brain?

Spongiform encephalopathy.

What is Toxoplasma gondii known for in immunodeficient individuals?

Infection is severe and often fatal.

How does Toxoplasma gondii affect healthy individuals?

It can lead to thrill-seeking behaviors and slower reaction times.

What are common mild symptoms of Toxoplasma gondii infection?

Sore throat, lymph node enlargement, and low-grade fever.

What is the primary source of Toxoplasma gondii infection in humans?

Raw or undercooked meat and unhygienic handling of cat feces.

What percentage of the population has had prior exposure to Toxoplasma gondii?

90%.

What is Subacute Sclerosing Panencephalitis (SSPE) associated with?

It is a complication of a previous measles infection.

What are the characteristics of prions?

They are proteinaceous infectious particles that contain no genetic material.

What diseases are caused by prions?

Transmissible spongiform encephalopathies (TSEs) such as Creutzfeldt-Jakob disease (CJD).

What are the signs and symptoms of Creutzfeldt-Jakob disease (CJD)?

Altered behavior, dementia, memory loss, and uncontrollable muscle contractions.

How does the prion cause damage in CJD?

It transforms normal proteins into abnormal forms, leading to brain damage.

What is the primary transmission route for rabies?

Bites from infected animals, primarily bats.

What are the initial symptoms of rabies?

Fever, nausea, vomiting, headache, and fatigue.

What is the incubation period for rabies?

1 to 2 months or even years, depending on the wound site.

What is the causative agent of tetanus?

Clostridium tetani.

What is the primary symptom of tetanus?

Lockjaw (tetanospasmin causing muscle contractions).

How does the botulinum toxin affect the body?

It prevents the release of acetylcholine, leading to flaccid paralysis.

What are the early symptoms of botulism?

Double vision, difficulty swallowing, and dizziness.

What is the usual time frame for symptoms to appear after botulinum toxin exposure?

12 to 72 hours.

What are the main reservoirs for rabies virus?

Wild mammals such as bats, raccoons, and skunks.

What is the recommended treatment after a potential rabies exposure?

A combination of passive and active postexposure immunization.

What is the global incidence of rabies cases estimated to be annually?

About 35,000 to 50,000 cases.

What is the primary method of preventing tetanus?

Vaccination and proper wound care.

What is the effect of the tetanospasmin toxin?

It blocks the inhibition of muscle contraction, causing uncontrollable muscle spasms.

What is the primary cause of botulism?

An exotoxin produced by Clostridium botulinum.

What are the common transmission routes for Toxoplasma gondii?

Ingestion of contaminated food, especially undercooked meat, and contact with infected cat feces.

What is the significance of prions in infectious diseases?

They cause neurodegenerative diseases with long incubation periods but rapid progression.

What is the typical outcome of untreated rabies?

It is almost always fatal.

What are the common sources of botulism outbreaks?

Poorly preserved foods and home-canned goods.

What is the role of hygiene in controlling Toxoplasma gondii?

Adequate cooking and hand washing after handling cats or cat feces are crucial.