Chapter 20: Objectives Flashcards
List three structural features of Neisseria that contribute to its pathogenicity.
- Fimbriae
- Capsules
- Variable cell wall antigens composed of lipooligosaccharide
Compare and contrast the symptoms of gonorrhea in men and women.
Gonorrhea in men:
- Painful urination and pus filled discharge
Gonorrhea in women:
- Often asymptomatic
- Can trigger pelvic inflammatory disease, proctitis, gingivitis, pharyngitis
Infection of children can result during childbirth (ophthalmia neonatorum)
Gonorrhea in men
- Painful urination
- Pus filled charge
Gonorrhea in women
- Often asymptomatic
- Can trigger pelvic inflammatory disease, proctitis, gingivitis, pharyngitis
Discuss the difficulties researchers face in developing an effective vaccine
against Neisseria gonorrhoeae
- Treatment is complicated due to resistant strains
- Broad spectrum antimicrobial drugs like cephalosporins
- Long term immunity does not develop due to variable surface antigens
What is cultured in Thayer-Martin agar
Neisseria gonorrhoeae
Diagnosis of Neisseria gonorrhoeae
- Asymptomatic cases identified with genetic probes
- Gram negative diplococci in pus
- Can be cultured in Thayer-Martin agar
Describe how meningococci: Neisseria meningitidis survive and thrive in humans
- 13 antigenic strains cause disease; A, B, C, and W135
- Can survive in neutrophils and macrophages
- Polysaccharide capsules resists lytic enzymes of phagocytes
- Neisseria meningitidis causes blebbing - a process of shedding outer membrane
What is blebbing
- A process in which the bacterium sheds extrusions of outer membrane
- Much of the damage caused by N. meningitidis results from blebbing
How is meningococcus: Neisseria meningitis transmitted?
- By respiratory droplets
- Bacteria transmitted among people living in close contact
- Most common cause of meningitis in individuals under 20 years
Meningococcal meningitis
Can cause death within 6 hours of symptoms:
- Abrupt sore throat
- Fever
- Headache
- Stiff neck
- Vomiting
- Convulsions
Petechiae
- Minute hemorrhagic skin lesions on the trunk and lower extremities, can combine together to form large black lesions
- Caused by Meningococcal
Meningococcal septicemia
- Also known as blood poisoning can also be life threatening
- LOS may trigger shock
- Petechiae - minute hemorrhagic skin lesions on the trunk and lower extremities, can combine together to form large black lesions
Discuss the epidemiology of meningococcal diseases
- Most common cause of meningitis in individuals under 20 years
- Respiratory droplets transmit the bacteria among people living in close contact, especially families, soldiers living in barracks, prisoners, and college students living in dormitories
Diagnosis of Neisseria meningitidis
- Gram negative diplococci in phagocytes of the cerebrospinal fluid
- Physician obtain a sample of cerebrospinal fluid using a needle inserted into the lower spinal canal; spinal tap
How to distinguish between Neisseria gonorrhoeae and N meningitidis
- N. gonorrhoeae is cultured on Thayer-Martin agar
- N. meningitidis can oxidize maltose in laboratory culture
Neisseria meningitidis treatment
- Intravenous antibiotics like ceftraxone, a cephalosporin
Prevention of Neisseria meningitidis
- Asymptomatic carriers are common which make eradication of meningococcal disease is unlikely
- Vaccination against strains A, C, Y, and W135
Describe how members of the family Enterobacteriaceae are distinguished from
members of the family Pasteurellaceae.
- Distinguish between members of the two families by preforming an oxidase test;
- Enterobacteriaceae are oxidase negative
- Pasteurellaceae are oxidase positive
Discuss how to distinguish between members of the family Enterobacteriaceae in the laboratory
- Biochemical tests
- Motility
- Colonial characteristics on a variety of selective and non-selective media (EX. MacConkey agar and blood agar)
All enterobacteriaceae bacteria are:
- Also known as enteric bacteria
- Gram negative
- Oxidase negative
- Able to metabolize nitrate to nitrite
Outer membrane that contains lipopolysaccharide:
- A core polysaccharide (common antigen)
- O polysaccharide
- Lipid A
Six virulence factors found in members of the family Enterobacteriaceae
- Fimbria
- Exotoxin
- Adhesin
- Plasmid (virulence genes)
- Iron-binding protein
- Hemolysin
Enterobacteriaceae virulence factor: Exotoxin
Exotoxins that cause a variety of symptoms such as diarrhea frequently located on plasmids, which increases the likelihood that they will be transferred among bacteria
Enterobacteriaceae virulence factor: Adhesin
Fimbriae and proteins called adhesins enable the bacteria to attach tightly to human cells
