Nervous system infections

Question 1

Meningitis characteristics?

Answer 1

Inflammation of the meninges (tissues surrounding the brain)
- anatomical syndrome: many different microorganisms can cause infection of meninges and all produce a similar set of symptoms
- can be caused by bacteria,viruses, or fungi
- more serious forms of meningitis are caused by bacteria
- meningitis in neonates is most often caused by different microorganisms than those that cause disease in children and adults

Question 2

Meningitis diagnosis?

Answer 2

• lumbar puncture/ spinal tap
• gram stain and or culture of CSF are performed
• treatment with broad-spectrum antibiotics started immediately

Question 3

Meningitis signs and symptoms?

Answer 3

• severe headache
• painful or stiff neck
• fever
• nausea and vomiting
• photophobia (sensitivity to light)
• skin rashes may be present in specific types of meningitis
• increased # of lymphocytes in CSF

Question 4

Bacterial meningitis causative agent?

Answer 4

Neisseria meningitidis
- gram-negative diplococci commonly known as meningococcus
- associated with epidemic forms of meningitis
- causes the most serious form of acute meningitis (15-20% of all cases)
- most cases occur in young children bc vaccination is not recommended until 11
- infection rate in most populations is 1% indicating well developed natural immunity
- treated meningococcemial disease has a 15% mortality rate

Question 5

Neisseria meningitidis transmission and epidemiology?

Answer 5

• bacteria don’t survive long in the environment
• usually acquired through close contact w/ secretions or droplets
• sporadic or epidemic incidence in late winter/early spring
• reservoir = humans harboring pathogen in the nasopharynx
• carriers living in close quarters w/ susceptible individuals more readily transmit diseased
• high risk groups = young and older children, and young adults

Question 6

Neisseria meningitidis Diagnosis?

Answer 6

• differential diagnosis must be done quickly
• meningococcal meningitis must be confirmed or ruled out because it can be rapidly fatal
• treatment is begun with this organism in mind until it is ruled out
• bacterial meningitis is considered a medical emergency

Question 7

Neisseria meningitidis diagnosis?

Answer 7

CSF, blood, or nasopharyngeal samples are stained and observed for characteristics of diplococci
- specific rapid tests are available for detecting capsular polysaccharides or cells directly from specimens without culturing
- Modified Thayer-Martin or chocolate agar is used for culture and incubated in a high CO2 atmosphere
- Presumptive indication of the genus obtained through gram stain and oxidase test

Question 8

Neisseria meningitidis treatment?

Answer 8

• vital that antibiotic therapy begins ASAP
• high dose of penicillin G given intravenously
• treatment for shock and intravascular clotting may also be required

Question 9

Neisseria meningitidis prevention?

Answer 9

individuals in close contact with w/ infected patients should receive preventative therapy with rifampin or tetracycline

Question 10

Meningoencephalitis characteristics?

Answer 10

inflammation of the brain and its protective membranes
caused by: naegleria fowleri and Acanthamoeba (amoebas)
accidental parasites that invade the body only under unusual circumstances

Question 11

Meningoencephalitis via Naegleria fowleri characteristics?

Answer 11

• usually aquired by people who have been swimming in warm, natural bodies of fresh water
• amoeba is forced into nasal passages as a result of swimming, diving, or other aquatic activities
• amoeba burrows into the nasal mucosa, multiplies, and migrates to the brain and surrounding structures
  results in PAM: primary amoebic meningoencephalitis
• causes massive destruction of brain and spinal tissue that results in hemorrhage and coma
• death occurs within a week

Question 12

Meningoencephalitis via Naegleria fowleri transmission and epidemiology?

Answer 12

• wide distribution in fresh bodies of water
• very common; children carry the amoeba as harmless biota, especially during summer months
• series of events leading to infection is rare

Question 13

Meningoencephalitis via Naegleria fowleri prevention and treatment?

Answer 13

• this meningoencephalitis advances so rapidly that treatment is usually futile
  
  • Early therapy with amphotericin B, sulfadiazine, or
    tetracycline in some combination can have some
    benefit
    Because of the wide distribution of the amoeba and its hardiness, no general method of control exists
    public swimming pools and baths must be adequately chlorinated and checked periodically for the amoeba

Question 14

Prion characteristics?

Answer 14

Proteinaceous infection particles that contain no genetic material
Causes Transmissible spongiform encephalopathies (TSEs)
- neurodegenerative diseases w/ long incubation but rapid progression
- Human TSEs = Creutzfeildt-Jkob disease (CJD); Genstmann-Strussler-Scheinker disease, and fatal familial insomnia
Animal TSEs = scrapie (sheep and goats), transmissible mink encephalopathy, bovine spongiform encephalopathy (BSE/mad cow disease)

Question 15

Prion CJD causative agent?

Answer 15

Prions cause transformation of normal host protein PrP that functions in normal brain development
- mutation causes a structural change in the protein, making PrP catalytic and able to convert other normal PrP proteins into the abnormal form
- self-propagating chain reaction leads to accumulation of altered PrP, plaques, and spongiform damage (holes in brian)

Question 16

Prion CJD signs and symptoms?

Answer 16

• altered behavior, dementia, memory loss, impaired senses, delirium, and premature senility
• Uncontrollable muscle contractions continue until death, usually within a year of diagnosis

Question 17

Prions transmissibility?

Answer 17

considered transmissible agents
- PrP proteins can be acquired through transmission
- genetic mutations of the PrP gene can also be passed on as heritable traits
- Prions are hardy; resistant to chemicals, radiation, heat, and prolonged autoclaving

Question 18

Prions CJD epidemiology?

Answer 18

• in late 90s, humans contracted vCJD after injecting meat from cattle infected with BSE
• cases of transmission of CJD via contaminated surgical instruments have been found
• normal disinfection and sterilization are not sufficient to eliminate prions from instruments and surfaces

Question 19

Rabies characteristics?

Answer 19

slow progressive zoonotic disease
- characterized by fatal encephalitis
- distinct pathogenesis and symptoms
Distributed almost worldwide

Question 20

Rabies signs and symptoms?

Answer 20

Incubation period of 1-2 months or more (depends on wound site, severity, and inoculation dose)
- shorter incubation with facial, scalp, or neck wounds (closer to the brian = less incubation)
Prodromal phase:
- fever, nausea, vomiting, headache, fatigue, and other nonspecific symptoms
Handful of patients have recovered in recent years from long term treatment but usually fatal

Question 21

Rabies Transmission?

Answer 21

Primary reservoirs are wild animals but both wild and domestic animals spread disease through bites, scratches, and inhalation of droplets
- majority transmitted to humans from bats
- majority US cases occur in rabies occur in wild animals

Question 22

Rabies epidemiology?

Answer 22

Animal reservoirs vary in the US (usually raccoons, bats and skunks)
- regional differences in the dominant reservoirs
- Skunks = California
- raccoons = East
- Foxes = Texas

Question 23

Rabies Diagnosis?

Answer 23

• Reverse transcription PCR used (saliva sample)
• Must be accompanied by the detection of antibodies to the virus in serum or spinal fluid
• skin biopsies are also used

Question 24

Rabies prevention and treatment?

Answer 24

BIte from wild or stray animal means animal must be assessed, meticulous wound care, and combination of passive and active postexposure immunization
- wound is infused with human rabies immune globulin (HRIG) to impede the speed of the virus
- Globulin also injected intramuscularly to provide immediate systemic protection
- full vaccination course is started

High-risk groups such as vets, animal handles, lab personnel, and travelers receive 3 doses of vaccine to protect

Question 25

Tetanus characteristics and causative agent?

Answer 25

Neuromuscular disease (also known as “lockjaw”)
- caused by Clostridium Tetani
- common resident of cultivated soil and
gastrointestinal tract of animals
- Gram-positive, endospore-forming bacillus
- endospores often swell in vegetative cells
- spores only produced under anaerobic conditions

Question 25

Tetanus characteristics and causative agent?

Answer 25

Neuromuscular disease (also known as “lockjaw”)
- caused by Clostridium Tetani
- common resident of cultivated soil and
gastrointestinal tract of animals
- Gram-positive, endospore-forming bacillus
- endospores often swell in vegetative cells
- spores only produced under anaerobic conditions

Question 26

Tetanus signs and symptoms?

Answer 26

First symptoms are clenching of jaw, followed by arching of back, flexion of arms, and extension of legs
- caused by Tetanospasmin (neurotoxin released by bacteria) that binds to target sites on peripheral motor neurons, spinal cord and brain, and in sympathetic nervous system
- toxin blocks the inhibition of muscle contraction, causing muscles to contract uncontrollably

Risis sardonicus: AKA “sardonic grin” conferred by lockjaw (looks like smiling)
- death most often occurs due to paralysis of the respiratory muscles

Question 27

Tetanus pathogenesis and virulence factors?

Answer 27

• presence of endospores in a wound is not sufficient to initiate infection
  
  • unable to invade damaged tissues readily
  • organism is anaerobic and endospores cannot
    become established unless tissue is necrotic/has
    poor blood supply
    As vegetative cells grow tetanospasmin is released into the infection site and spread

Question 28

Tetanus transmission and epidemiology?

Answer 28

Endospores enter the body through puncture wounds, burns, umbilical stumps, frostbite, crushed body part
- most cases of tetanus occur among geriatric patients and IV drug users
- Historically maternal & neonatal tetanus cases high but was improvised with more hygienic delivery practices and vaccination

Question 29

Tetanus treatment?

Answer 29

• patient w/ clinical appearance should receive immediate antitoxin therapy w human tetanus immune globulin (TIG) and penicillin G

Question 30

Tetanus prevention?

Answer 30

Recommended vaccination series:
* 1- to 3-month-old babies consists of three injections given 2 months apart, followed by boosters at 1 and 4 years
* Protection lasts 10 years
* Pregnant women should be vaccinated
* Toxoid with TIG should be given to injured persons who have never been immunized or whose last booster was received more than 10 years previously

Question 31

Botulism characteristics?

Answer 31

intoxication caused by an exotoxin associated with eating poorly preserved foods
- can also occur as a true infection
- modern techniques of food preservation and medical treatment reduce the incidence and mortality rate

Question 32

What are the 3 forms of botulism?

Answer 32

infant
food-borne
wound

Question 33

Botulism signs and symptoms?

Answer 33

Botulinum (neurotoxin produced by C. botulinum) results in flaccid paralysis, a loss of ability to contract muscles

Early symptoms:
- double vision, difficulty swallowing, dizziness, no sensory or mental lapse
Later symptoms:
- descending muscular paralysis, respiratory compromise
- death usually results from respiratory arrest ( mechanical respirators have reduced fatality to 10%)

Question 34

Botulism causative agent?

Answer 34

Clostridium botulinum
- endospore-forming anaerobe
- does damage through the release of an exotoxin
- species has 7 types that vary in distributions among animals, regions, and types of exotoxin

Question 35

Botulism culture and diagnosis?

Answer 35

• Diagnostic standards are different for 3 presentations
• CDC and state health department need to be notified if a case is suspected

Question 36

Botulism prevention and treatment?

Answer 36

• Antitoxin provided by CDC soon after diagnosis can prevent worst outcomes of disease
• patients are managed w/ respiratory and cardiac support systems
• hospitalization required in all cases
• recovery takes weeks (5% mortality rate)