Neisseria, Haemophilus and Bordetella Flashcards Preview

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Flashcards in Neisseria, Haemophilus and Bordetella Deck (50):
1

What Gram are Neisseria?

Gram Negative

2

What part of N. meningitidis results in septic shock?

The lipopolysaccharide (endotoxin) of Neisseria meningitidis is a potent stimulator of inflammation resulting in the septic shock syndrome.

3

What are the 4 general characteristics of Neisseria?

1. Gram-negative "kidney bean" diplococci
2. Endotoxic lipopolysaccharide complexed with protein in outer membrane
3. Growth enhanced in CO2
4. Fastidious species require enriched media (chocolate agar)

4

Are Neisseria oxidase positive or negative?

OXIDASE POSITIVE

5

What is the only sugar N. gonorrhea oxidizes?

Glucose

6

What sugars does N. meningitidis oxidize?

Glucose and Maltose

7

What immune component is required to fight Neisseria?

Complement

8

What 2 structures confer virulence to Neisseria menigitidis?

Pili - attachment
Capsule - bloodstream invasion and survival and possibly CNS penetration

9

What is the pathogenesis of Neisseria meningitidis?

1. Attachment - microvilli of nonciliated nasopharyngeal cells via pili
2. Traverse cell in vesicle to submucosa
3. Damage ciliated cells
4. Bloodstream survival enhanced by antiphagocytic
polysaccharide capsule
5. Endotoxin mediated activation of complement leading to shock and hemorrhage
6. CNS inflammation generated by cell wall peptidoglycan, LPS, other bacterial products and is mediated by IL-1 and TNF

10

What are the clinical manifestations of N. meningitidis infection?

1. Respiratory colonization followed by overt disease or transient carrier state
2. Meningitis
3. Skin: petechiae → purpura
4. Meningococcemia: shock, hemorrhage and purpura,
destruction of adrenals

11

What are the identifying features of N. meningitidis in the lab?

1. Gram smear- Cerebrospinal fluid (CSF)
2. Cultures- CSF, blood, skin
3. Cultures – Oxidase positive, oxidize glucose and maltose
4. Nonselective media (blood or chocolate agar)

12

What is the main treatment for N meningitides?

Penicillin - resistance uncommon

13

What serotype is not used in N. meningitides vaccines?

Serogroup B cannot be used in the vaccine as it is non-immunogenic

14

What is PorB of N. gonorrhea?

PorB - Outer membrane protein I (Por proteins) – Porin
a. Pores (channels) in organism
b. Facilitates epithelial cell invasion

15

What is Opa of N. gonorrhea?

Opa - adherence proteins confer opaque appearance to colony which results from Opa-mediated adherence between cells

Opaque associated with localized
Transparent disseminated

16

What 2 things contribute to the antigenic diversity of N. gonorrhea?

Pili - Antigenic variation
Opa – Phase variation

17

How does pili antigen variation occur in N. gonorrhea?

Genetic recombination by transfer of variable sequences form unexpressed (silent) loci, pilS to expression locus, pilE

18

How does Opa phase variation occur in N gonorrhea?

Can switch on and off as many as 11 different Opa
genes throughout the genome creating variation

19

What is the transmission of N. gonorrhea?

Mucosal transmission (genital, mouth, anus, eye) by direct contact

20

What is the pathogenesis of N. gonorrhea?

1. Attachment via pili and Opa
Genetic variation of ligands evades immune responses

2. Invasion and damage
a. Epithelial cell invasion involves PorB and other outer membrane proteins
b. Epithelial cell invasion has been demonstrated in salpingitis, but role in uncomplicated mucosal infection not demonstrated
c. Lipopolysaccharide and peptidoglycan fragments incite inflammatory response

3. Spread
a. Prostate, epididymis and paracervical glands by direct
extension
b. Possibly carried by sperm to fallopian tubes
c. Serum resistant strains invade the bloodstream and
disseminate to skin, joints

21

What are the clinical manifestations of N. gonorrhea?

Urethritis
Cervicitis
Prostatitis and pharyngitis - often asymptomatic
Conjunctivitis

22

How does N. gonorrhea evade the immune system?

a. Antigenic and phase variation evade immune response
b. Resist phagocytosis (Opa and pili)
c. IgA 1 protease
d. Evade serum antibody and complement mediated killing
e. Bind "blocking antibodies" to Rmp – Reduction Modifiable Protein

23

What are the methods for the identification of N. gonorrhea?

Gram Stain (95% sensitive in men; less in women)
Culture
Gene Amplification

24

What is the treatment for N. gonorrhea?

Ceftriaxone PLUS azithromycin

Antibiotic resistance is a BIG problem with N. gonorrhea

25

What are the characteristics of Haemophilus influenzae?

It is a small Gram-negative coccobacilli
Grows on chocolate agar (lysed blood)

26

What factors does H. influenzae require to grow?

X factor (hematin)
Y factor (NAD)

27

What is the main virulence factor of H. influenzae?

Type B capsule - polyribitol phosphate (PRP)

28

What led to the drastic decrease in the rate of H. influenzae infection?

Type B decreased the rate of it by 94%

29

What is the transmission of H. influenzae?

Respiratory droplets

30

What is the transmission of N. meningtidis?

Respiratory droplets

31

What is the pathogenesis of H. influenzae?

• Adhere - Pili, OMPs
• Transcytose like Neisseria
• Encapsulated strains invade bloodstream
• Endotoxin - local and systemic inflammation

32

What are the clinical manifestations of Type B H. influenzae?

a) Meningitis - children

33

What are the manifestations of unencapsulated H. influenzae?

a) Otitis media
b) Acute and chronic sinusitis
c) Bronchitis

34

What is the treatment for H. influenzae?

Ampicillin
Cephalosporins

Vaccine as preventative measure

35

H. parainfluenzae Disease

Respiratory

36

H. aegyptius Disease

Conjunctivitis

37

H. (Aggregatibacter) aphrophilus Disease

Endocarditis

38

H. ducreyi Disease

Chancroid (STD)

39

What are the characteristics of Bordella pertussis?

Aerobic
Gram-negative coccobacilli

40

What are the main virulence factors of B. pertussis?

• Adhesins
• Pertussis Toxin
• Tracheal cytotoxin - peptidoglycan fragment

41

What is the function of Pertussis Toxin?

AB subunit - A - S1 enzymatic, B – S2-S5 binding Subunits

A catalyzes ADP (from NADP) ribosylation of a
cellular regulatory protein (G- protein) which prevents inactivation of activated adenylate cyclase

B subunits bind to receptors on ciliated respiratory cells and phagocytic cells

Biologic effects of PT include: Increased respiratory secretions, mucus production and lymphocytosis

42

What is the function of Tracheal cytotoxin?

Tracheal cytotoxin – fragment of peptidoglycan that binds to and causes extrusion of ciliated respiratory epithelial cells. The toxin also stimulates IL-1 release (fever)

43

What is the function of Dermonecrotic toxin?

Dermonecrotic toxin – causes ischemic necrosis

44

What is B. pertussis transmitted by?

Spread by airborne droplets, highly infectious

45

What is the reservoir of B. pertussis?

Sub-clinical adults

46

What is the pathogenesis of B. pertussis?

1. B. pertussis attaches to ciliated epithelial cells by adhesins
2. Tracheal cytotoxin and possibly other toxins destroy ciliated
cells, extrude them from border
3. Adenylate cyclase exerts inhibitory effects on phagocytic cells
4. Pertussis toxin produces systemic manifestations including enhanced respiratory secretions and mucus production
contributing to cough as well as lymphocytosis
5. Lipopolysaccharide – stimulates cytokine release

47

What are the clinical manifestations of B. pertussis?

Catarrhal stage - rhinorrhea, fever, sneezing, anorexia

Paroxysmal cough - up to 50 times a day for 2-4 weeks.
Inspiratory whoop, vomiting, mucoid secretions, marked
lymphocytosis

Convalescent stage - cough gradually fades

48

What is required for B. pertussis culture?

Specialized media – Regan-Lowe charcoal medium

49

What is the treatment for B. pertussis?

Azithromycin, clarithromycin, erythromycin

50

What are the vaccines available for B. pertussis?

DTaP, which contains one of the acellular pertussis vaccines, made from purified, detoxified pertussis toxin (PT), filamentous hemagglutinin (Fha), and Pertactin (Pn).

A dose of vaccine containing a reduced amount of pertussis antigens, Tdap, is recommended for all adults in place of a routine.

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