chapter22 Flashcards
define meningitis
inflammation of meninges
define encephalitis
inflammation of the brain
define meningoencephalitis
inflammation of both meninges and the brain
initial symptoms of meningitis include?
fever, headache and stiff neck
nausea and vomiting usually follow
what are the types of pathogens that could cause meningitis
viruses, bacteria, protozoa and fungi
most common cause of meningitis?
viruses
the mild type of meningitis is?
viral meningitis
haemophilus influenzae is gram…
negative
does haemophilus influenzae require oxygen?
yes its aerobic
name a bacteria of the normal throat microbiota
haemophilus influenzae
pathogenicity of haemophilus influenzae is due to
capsule antigen type B
H. influenzae meningitis is prevented by
the Hib vaccine
whats the most prevalent type of bacterial meningitis ?
Haemophilus influenzae meningitis
most people affected with H. influenzae meningitis are of age….
6 months to 4 years
does Neisseria meningitidis require oxygen?
yes its aerobic
Neisseria meningitidis is gram…
negative
describe the shape of Neisseria meningitidis
diplococcus with a capsule
how many serotypes associated with meningitis does Neisseria meningitidis have?
6 serotypes
Neisseria meningitidis meningitis is also called?
meningococcal meningitis
vaccination for Neisseria meningitidis meningitis protects from all serotypes except
Serotype X
Neisseria meningitidis meningitis initial symptoms include
rash, bacteremia and throat infection
Streptococcus pneumoniae Meningitis is also called
pneumococcal meningitis
S. pneumoniae is gram…
positive
describe the shape of S. pneumoniae
encapsulated diplocooccus
S. pneumoniae causes other diseases including
otits media
pneumonia
S. pneumoniae Meningitis is prevented by
conjugated vaccine
70% of people with S. pneumoniae are
healthy nasopharyngeal carriers
how do you diagnose a case of bacterial meningitis?
by taking a sample of CSF obtained by a spinal tap or lumbar puncture
how do you stain a sample of CSF
a single gram stain is often useful to identify the pathogen with considerable reliability
when is chemotherapy of suspected cases of bacterial meningitis usually initiated?
before identification of the pathogen is complete
whats the first choice of antibiotics for bacterial meningitis?
Broad-spectrum third-generation cephalosporins
Listeriosis is caused by the bacterium…
Listeria monocytogenes
Listeria monocytogenes is gram…
positive
describe the shape of L. monocytogenes
rod shaped (bacilli)
the method of transmission of L. monocytogenes is usually
foodborne
how is the effect of Listeria monocytogenes different in healthy humans than compromised ones?
in healthy individuals: mild and often symptomless
compromised immunity individuals: invades the CNS causing meningitis
presence of Listeria monocytogenes in the blood causes…
sepsis
Listeria monocytogenes is usually shed through…
feces
what are the important factors of virulence in Listeria monocytogenes?
- it proliferates inside phagocytes in the liver instead of being destroyed
- it has the ability to move from one phagocyte to another
whats the effect of Listeria monocytogenes on pregnant women and their fetus?
- on the pregnant woman: no more than mild flulike symptoms
- on the fetus: infected via the placenta, leads to abortion or stillborn infant
the bacterium that causes tetanus is called
Clostridium tetani
C. tetani is gram…
positive
Does C. tetani require oxygen?
no its an obligate anaerobe that grows in deep wounds with anaerobic conditions
the toxin released from dead cells in tetanus is known as
tetanospasmin neurotoxin
how does tetanospasmin neurotoxin cause tetanus?
it enters CNS and blocks the relaxation pathway of muscles causing spasms
death of tetanus is usually due to
spasms iof respiratory muscles
tetanus is prevented by
vaccination with a tetanus toxoid (DTaP)
how does DTaP work to prevent tetanus
stimulates production of antibodies that neutralize the tetanospasmin neurotoxin
treatment of tetanus
tetanus immune globulin TIG
the process of removal of tissue affected with tetanus is called
debridement
botulism is caused by the bacterium
Clostridium botulinum
Clostridium botulinum is gram…
positive
does Clostridium botulinum require oxygen
no its an obligate anaerobe
name two endospore forming bacteria
Clostridium botulinum
Clostridium tetani
intoxication in botulism comes from
ingesting the botulinal exotoxin
what part of the nerve does the botulinal exotoxin attack
the synaptic end
the botulinal exotoxin blocks release of…
the neurotransmitter acetylcholine
causing flaccid paralysis
death of botulism usually comes from
cardiac or respiratory failure
infant botulism can be caused by…
ingestion of soil or endospore contaminated materials
but mostly because of ingestion of honey
growth of C. botulinum in wounds is called
wound botulism
the treatment of botulism relies heavily on..
supportive care
antitoxins of A, B and E botulism toxins are aimed at…
neutralizing the different types of the toxin
the antitoxin derived from horses and used for adults can cause serious side effects, including:
serum sickness
anaphylaxis
immune complexes formed by reaction with antigens in the antitoxin, is the definition of?
serum sickness
how can we prevent botulism?
- proper canning of foods
- the use of nitrites to inhibit spore germination
nitrites also inhibit C. botulinum growth after endospore germination
Hansen’s disease is another name for
leprosy (الجُذام)
leprosy is caused by
mycobacterium leprae
describe Mycobacterium leprae
acid fast rod (bacilli)
grows best at 30°C
mycobacterium leprae usually gorws in…
peripheral nerves
skin cells
mycobacterium leprae can cause leprosy by…
invading the myelin sheaths of peripheral nerves
one virulence factor of M. leprae is…
that it survives macrophages
what are the methods of transmission of leprosy?
- prolonged contact with an infected person
- inhalation of secretions
what are the two types of leprosy?
- tuberculoid form (neural)
- lepromatous form (progressive)
loss of sensation of the skin is a characteristic of …. leprosy
tuberculoid from
effect on mucos membranes and disfiguring nodules all over the body are characteristics of ….. leprosy
lepromatous form
how do you diagnose leprosy?
skin biopsy
skin smear and a blood test
…. are usually used for treatment of leprosy
antibiotics
poliomyelitis (شلل الاطفال) is caused by
poliovirus
initial symptoms of poliomyelitis include
sore throat and nausea
what effects does poliovirus leave if it enters the CNS?
destruction of motor nerve cells
death of poliomyelitis is due to
respiratory failure
rabies is caused by
rabies virus
rabies virus belongs to the genus…
lyssavirus (bullet shaped)
the genetic material of rabies virus contains …
single stranded RNA
why do mutant strains of rabies virus develop easily?
because it has no proofreading capability
how is rabies transmitted
- mostly by the saliva of an animal bite
- rarely can cross mucos membranes
the most common cause of rabies is
silver haired bats
what are the initial symptoms of rabies?
muscle spasms of the mouth and pharynx
hydrophobia
rabies virus multiples in…
skeletal muscles
rabies virus travels through … to the brain to cause encephalitis
the PNS
average incubation period for rabies virus?
30-50 days
viral inclusions into host cells are called
negri bodies
rabies virus usually forms negri bodies in the…
brain stem
diagnosis of rabies in laboratory is usually done by
direct fluorescent-antibody (DFA): detection of viral antigen
what’s postexposure prophylaxis (PEP)?
vaccine: human diploid cell vaccine (HDCV)
passive immunization: human rabies immue globulin (RIG)
when are we supposed to use PEP?
right after the person gets bit by a rabid animal
before the end of incubation period of rabies virus
whats an arbovirus?
arthropod borne virus
arboviral encephalitis are caused by
mosquito borne viruses
name 3 examples of arboviral encephalitis?
- Eastern equine encephalitis EEE
- Western equine encephalitis WEE
- Japanese encephalitis
symptoms of WEE and EEE include?
deafness
neurological damage
brain damage
give an example of arboviruses?
West Nile virus (WNV)
virus maintained in the bird-mosquito-bird cycle?
west nile virus
results of infection with WNV include:
poliolike paralysis
fatal encephalitis
japanese encephalitis is diagnosed by..l
ELISA test to identify igM antibodies
ZIka virus is primarily transmitted by
the bite of infected Aedes spp. mosquitoes
other ways of transmission of zika virus include
sexual transmission
mother to child
blood transfusions
zika virus infection during pregnancy increases the risk of…
microcephaly in infants
how can you possibly diagnose zika virus disease (ZVD)?
by reverse transcriptase PCR
name 4 viral infections of nervous system?
poliomyelitis
rabies
arboviral encephalitis
zika virus disease
name 5 bacterial diseases that affect the nervous system?
tetanus
botulism
meningitis (H. influenzae, N. meningitidis, S. pneumoniae)
listeriosis
leprosy
Cryptococcosis is another name for…
Cryptococcus neoformans meningitis (fungal disease)
what type ot fungus is C. neoformans?
soil fungus associated with chicken and pigeon droppings
C. neoformans is usually transmitted via…
respiratory route through dried contaminated droppings
whats the effect of C. neoformans in immunocompromised patients?
it spreads through blood to the CNS
African trypanosomiasis is a …. disease that affects the …. system
protozoan
nervous
sleeping sickness is another name for?
african trypanosomiasis
what are the two types of brucei that affect humans?
trypanosoma brucei gambiense
trypanosoma brucei rhodesiense
…. is a trypanosoma that the only reservoir of is human.
trypanosoma brucei gambiense
whats the reservoir of trypanosoma brucei rhodesiense?
wild animals and livestock
brucei rhodesiense is transmitted from animals to humans by…
tsetse fly
why is it difficult to develop a vaccine for african trypanosomiasis?
because the parasite evades antibodies through antigenic variations
what are the three parasites that cause amebic meningoencephalitis?
- Naegleria fowleri
- Acanthamoeba spp.
- Balamuthia mandrillaris
the parasite that causes primary amebic meningoencephalitis is called…
Naegleria fowleri
name 2 parasites that could possibly cause granulomatous amebic encephalitis (GAE)?
Acanthamoeba spp.
Balamuthia mandrillaris
signs of primary amebic meningoencephalitis (PAM) include?
N. fowleri infects nasal mucosa from swimming water
penetrates the brain
feeds on brain tissue
multiple lesions around the brain, called granulomas are a sign of?
granulmatous amebic encephalitis
