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Microbiology Ch. 22: Microbial Diseases of the Nervous System

Tortora; Microbiology 265 Ch. 22: Microbial Diseases of the Nervous System
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Central Nervous System (CNS)
consists of the brain and spinal cord
Peripheral Nervous System (PNS)
consists of all the nerves that branch off from the brain and spinal cord
meningitis
general term for the inflammation of the meninges

*The meninges are the dura mater, arachnoid mater, and the pia mater.
encephalitis
general term for the inflammation of the brain itself
meningoencephalitis
general term for the inflammation of the brain and the meninges
Meningitis and Encephalitis
BACTERIAL DISEASES:
Haemophilus influenzae meningitis
Meningococcal meningitis
Pneumococcal meningitis
Listeriosis

FUNGAL DISEASE:
Cryptococcosis

PROTOZOAN DISEASES:
Primary amebic meningoencephalitis
Granulomatous amebic encephalitis
BACTERIAL Diseases that can cause meningitis and/or encephalitis
Haemophilus influenzae meningitis
Meningococcal meningitis
Pneumococcal meningitis
Listeriosis

*Diagnosis of bacterial meningitis requires a sample of cerebrospinal fluid obtained by a spinal tap. A Gram stain is often useful.
FUNGAL Diseases that can cause meningitis and/or encephalitis
Cryptococcosis
PROTOZOAN Diseases that can cause meningitis and/or encephalitis
Primary amebic meningoencephalitis
Granulomatous amebic encephalitis
Haemophilus influenzae meningitis
PATHOGEN: Haemophilus influenzae
MORPHOLOGY: Gram-negative rod

PORTAL OF ENTRY: Respiratory tract
METHOD OF TRANSMISSION: Endogenous infection; aerosols

TREATMENT: Cephalosporin
Prevention: Capsular Hib vaccine
Meningococcal meningitis
PATHOGEN: Neisseria meningitidis
MORPHOLOGY: Gram-negative diplococcus

PORTAL OF ENTRY: Respiratory tract
METHOD OF TRANSMISSION: Aerosols

TREATMENT: Cephalosporin
Prevention: Capsular vaccine against serotypes A, C, Y W- 135
Pneumococcal meningitis
PATHOGEN: Streptococcus pneumoniae
MORPHOLOGY: Gram-positive cocci

PORTAL OF ENTRY: Respiratory tract
METHOD OF TRANSMISSION: Aerosols

TREATMENT: Cephalosporin
Prevention: Polysaccharide vaccine
Listeriosis
PATHOGEN: Listeria monocytogenes
MORPHOLOGY: Gram-positive facultative anaerobe

PORTAL OF ENTRY: Mouth
METHOD OF TRANSMISSION: Foodborne infection

TREATMENT: Penicillin G
Prevention: Pasteurizing and cooking food
Cryptococcosis
PATHOGEN: Cryptococcus neoformans
C. grubii
C. gattii

PORTAL OF ENTRY: Respiratory tract
METHOD OF TRANSMISSION: Inhaling soil contaminated with spores

TREATMENT: Amphotericin B, flucytosine

*The disease is transmitted mainly by the inhalation of dried, contaminated droppings - esp. of pigeons.
Primary amebic meningoencephalitis
PATHOGEN: Naegleria fowleri
PORTAL OF ENTRY: Mucous membrane

METHOD OF TRANSMISSION: Swimming

TREATMENT: Amphotericin B

These protozoa are found in freshwater. The most common victims are children who swim in ponds or streams.
Granulomatous amebic encephalitis
PATHOGEN: Acanthamoeba spp;
Balamuthia mandrillaris

PORTAL OF ENTRY: Mucous membranes
METHOD OF TRANSMISSION: Swimming

TREATMENT: Amphotericin B

These protozoa are found in freshwater. The most common victims are children who swim in ponds or streams.
Microbial Diseases with Neurological Symptoms or Paralysis
BACTERIAL DISEASES:
Tetanus
Botulism
Leprosy

VIRAL DISEASES:
Poliomyelitis
Rabies

PROTOZOAN DISEASE:
African trypanosomiasis

PRION DISEASES:
Creutzfeldt-Jakob Disease
Kuru
BACTERIAL Diseases with Neurological Symptoms or Paralysis
Tetanus
Botulism
Leprosy
VIRAL Diseases with Neurological Symptoms or Paralysis
Poliomyelitis
Rabies
PROTOZOAN Disease with Neurological Symptoms or Paralysis
African trypanosomiasis
PRION Diseases with Neurological Symptoms or Paralysis
Creutzfeldt-Jakob Disease
Kuru
Tetanus
PATHOGEN: Clostridium tetani
MORPHOLOGY: Gram-positive rod

SYMPTOMS: Lockjaw; muscle spasms
METHOD OF TRANSMISSION: Puncture wound

TREATMENT: Tetanus immune globulin (TIG); antibiotics
Prevention: Toxoid vaccine (DTaP, Td)
Botulism
PATHOGEN: Clostridium botulinum
MORPHOLOGY: Gram-positive rod

SYMPTOMS: Flaccid paralysis
METHOD OF TRANSMISSION: foodborne intoxication

TREATMENT: Antitoxin
Prevention: Proper canning of foods; infants should not have honey
Leprosy
PATHOGEN: Mycobacterium leprae
MORPHOLOGY: Acid-fast rod. Aerobic, intracellular bacterium

SYMPTOMS: Loss of sensation in skin; disfiguring nodules
METHOD OF TRANSMISSION: Probably prolonged contact with contaminated secretions

TREATMENT: Dapsone, rifampin, clofaximine
Prevention: Possibly BCG vaccine
Poliomyelitis
PATHOGEN: Poliovirus
SYMPTOMS: Headache, sore throat, stiff neck; paralysis if motor nerves infected

METHOD OF TRANSMISSION: Ingesting contaminated water (fecal-oral route)

TREATMENT: Mechanical breathing aid (iron lung)
Prevention: Inactivated polio vaccine (E-IPV)
Rabies
PATHOGEN: Lyssavirus, including rabies virus
SYMPTOMS: Fatal infection; early symptoms include agitation, muscle spasms, difficulty swallowing

METHOD OF TRANSMISSION: Animal bite

TREATMENT: Postexposure treatment: rabies immunoglobulin plus vaccine (RIG)
Prevention: Human diploid cell vaccine for high-risk individuals; vaccination of domestic animals
African trypanosomiasis
PATHOGEN: Trypanosoma brucei rhodiense,
T. b. gambiense

SYMPTOMS: Fatal infection; early symptoms (headache, fever) progress to coma
METHOD OF TRANSMISSION: Tsetse fly

TREATMENT: Suramin; pentamidine
Prevention: Vector control

AKA "African sleeping sickness"
Creutzfeldt-Jakob disease
PATHOGEN: Prion

SYMPTOMS: Fatal infection; neurologic symptoms include trembling
METHOD OF TRANSMISSION: Inherited; ingested; transplants

TREATMENT: none
Prevention: none

*Mad cow disease
Kuru
PATHOGEN: Prion

SYMPTOMS: Fatal infection; neurologic symptoms include trembling
METHOD OF TRANSMISSION: Contact or ingestion

TREATMENT: none
Prevention: none
Practice Test Questions
...
A 30-yr old female was hospitalized after she experienced convulsions. On examination she was alert and oriented and complained of a fever, headache, and stiff neck. Her symptoms could be due to all of the following except...

A) Clostridium botulinum
B) Listeria monocytogenes
C) Naegleria fowleri
D) Streptococcus pneumoniae
E) None of the above
A) Clostridium botulinum




The prodromal symptoms of meningitis are: fever, headache, and stiff neck.
Also, meningitis is a general term for the inflammation of the meninges.
A 30-yr old female was hospitalized after she experienced convulsions. On examination she was alert and oriented and complained of a fever, headached, and stiff neck. Which of the following is most likely to provide rapid identification of the cause of her symptoms?

A) Gram stain of cerebrospinal fluid
B) Gram stain of throat culture
C) Biopsy of brain tissue
D) Check serum antibodies
E) None of the above; it can't be diagnosed
A) Gram stain of cerebrospinal fluid



Suspicion: bacterial meningitis
The quickest way to determine the causative agent of the bacterial meningitis is with a gram stain of the CSF.
All of the following are true about the lepromin test except...

A) It consists of human tissue extract
B) It detects the presence of anti-M. leprae antibodies
C) It is negative in the lepromatous form
D) It consists of M. leprae
E) None of the above
A) It consists of human tissue extract
A 1-yr old female was hospitalized with fever, lethargy, and rash. Gram-negative, oxidase-positive cocci were cultured from her cerebrospinal fluid. Her symptoms were caused by...

A) A prion
B) Clostridium tetani
C) Mycobacterium leprae
D) Neisseria meningitidis
E) Rabies
D) Neisseria meningitidis


Gram-negative cocci
Which of the following vaccines is a cause of the disease it is designed to prevent?

A) Tetanus toxoid vaccine
B) Oral polio vaccine
C) Inactivated polio vaccine
D) Haemophilus influenzae capsule vaccine
B) Oral polio vaccine



On rare occasions, the attenuated strain used in the vaccine may revert to a virulent strain and transmit the disease.