Neisseria, Haemophilus and Bordetella Flashcards
Describe morphology and major identifying cellular characteristics of Neisseria spp.
- Is it gram neg or pos?
- Gram negative “kidney bean” diplococci
- Endotoxin LPS complexed with protein in outer membrane
- Capsules and pili
Is Neisseria catalase pos or neg?
Oxidase pos or neg?
What’s its growth enhanced by?
- Catalase positive
- Oxidase positive
- CO2
N. gonorrhoeae vs. N. meningiditis.
- Which are blood agar +/-?
- Which are oxidase +/-?
- Which are glucose +/-?
- Which are maltose +/-?
- Blood agar: gonor is -, mening is +
- Oxidase: both are +
- Glucose: both are +
- Maltose: gonor is -, mening is +
List two important virulence characteristics of Neisseria meningitidis.
- Capsule
- LOS (like LPS; cell damage and systemic inflammation)
List two important virulence characteristics of Neisseria gonorrhoeae.
Pili and OMPs
People who have ____________ deficiencies are more susceptible to Neisseria infection.
C5-C8 Complement
How is meningococcal disease spread?
Through respiratory droplets
What demo in the US is most susceptible to N. meningiditis?
Children under 5, teens, and young adults
- Also gay men (sexually transmitted)
What are the 2 major manifestations of N. meningiditis infection?
Which is more important?
What are some other, less common associated conditions?
- Meningococcemia (most important)
- Meningitis
- Others: pneumonia, arthritis, pericarditis, urethritis
What are the sx of meningococcemia?
- Sudden onset very high fever and chills
- Shock
- Hemorrhage
- Purpura
- Adrenal hemorrhage
What are the sx of meningitis?
- Headache
- Mental status changes
- Neurological signs
- Skin: petecheae purpura
In testing for N. meningiditis, what would you want to obtain for a gram stain?
What could you culture?
Would you use blood or chocolate agar, or either?
- CSF
- CSF, blood skin
- Chocolate
What is the most common antimicrobial used to treat N. meningiditis?
Ceftriaxone
can use PCN G if sensitive as well
What are the most important serogroups of N meningiditis (polysaccharide capulse) that might be worth knowing?
Which one is not immunogenic?
13 serogroups. A, B, C, Y, W-135
- Immunogenic except Group B
Who should get the vaccine for N meningiditis?
What’s it conjugated to?
All kids at age 11, college kids, at-risk adults
- Conjugated to diphtheria
Why is the capsule considered a virulence factor for N. meningiditis?
- Enhances bloodstream invasion and survival
- Enhances CNS penetration
- Avoids phagocytosis until opsonized
How does the N. meningiditis get to its target body site? (very general)
Adheres by pili, crosses cell, bloodstream, BBB
Does N. Meningiditis tend to have small or pandemic outbreaks?
Small outbreaks (e.g. gay men)
What 4 antigenic structures are important for N. gonorrhoeae?
- Pili
- PorB
- Opa
- Rmp
How does PorB act as a virulence factor for N. gonorrhoeae?
Promotes intracellular survival by preventing phagolysosome fusion
- Allows for epithelial cell invasion
What is Opa in N. gonorrhoeae and what does it do when expressed?
- What do each of its 2 forms mean in terms of dz spread?
Adherence proteins confer opaque appearance to colony when expressed
- Opaque: localized disease
- Transparent: disseminated disease
How does Rmp act as a virulence factor for N. gonorrhoeae?
Stimulate blocking ABs
**Differentiate antigenic variation occurring in pili from phase variation occurring in Opa. (obvious test question)
- Pili: DNA recombination involving transfer of variable sequences from unexpressed (silent) loci, pilS, to expression locus, pilE
- Up to 11 different Opa genes switch on and off Opa genes by varying number of 5 nucleotide (CTCTT)n repeats in the leader sequence encoding the Opa gene
- Alteration in number or repeats turns on or off expression of the gene
How is N. gonorrhoeae spread?
What demo’s have high rates?
Transmission across mucosal surfaces by direct contact
- High rates amongst adolescents and young adults
What 2 proteins help N. gonorrhoeae attach and resist phagocytosis?
Pili + Opa
What does LOS do during N. gonorrhoeae?
Inflammatory response and damage
What are 2 mechs N. gonorrhoeae uses to evade serum antibody and complement mediated killing?
- LOS sialylation (coats it)
- Rmp stimulates “blocking antibodies” to protect other surface antigens (Por protein, LOS)
List important clinical conditions caused by Neisseria gonorrhoeae
- Urethritis
- Cervicitis
- Skin lesions (distal extremities)
- Polyarticular tenosynovitis
- Septic arthritis
List the methods of laboratory diagnosis of infection caused by Neisseria
gonorrhoeae. (3, in order)
(some review from earlier)
- Gram stain: urethra, cervix, joint (95% sensitive in men, 50-70% in women)
- Culture (Require chocolate agar and CO2
o Martin Lewis - antibiotics select for N. gonorrhoeae
o Oxidase positive. Oxidize glucose, NOT maltose - Nucleic acid amplification (PCR)
- Cannot test antibiotic susceptibility
What is the only currently effective tx for N gonorrhoeae?
What is it often combined w/ and why?
Ceftriaxone
- There is often concurrent chlamydia, so give either azithromycin or dixycycline as well
N. gonorrhoeae often starts at the cervix or urethra, but where can if often spread to? (3)
- What if it becomes disseminated?
Prostate, epididymis, fallopian tube
- joints, skin
Identify the major reason that development of vaccines against N. gonorrhoeae have been unsuccessful.
(not sure)
Is Haemophilus influenzae gram pos or neg?
What shape is it?
- Gram negative
- Coccobacillus
What are the different serotype classifications of H. influenzae?
- Which is responsible for the serious invasive dz?
Serotypes a-f (polysaccharide capsule)
- b most important (polyribitol phosphate)
What is the virulence of H influenzae’s capsule?
Besides the polysaccharide capsule for serotyping, what are two other important virulence factors for H. influenzae?
Antiphagocytic
- Pili
- Endotoxin
There has been a 94% decline in H. flu type b due to universal vaccination of children. What other bacterial dz has been on the decline due to this result?
Bacterial meningitis (conjugated vaccine, only for type b capsule)
How is H influenzae transmitted?
- Describe it’s general method of infection
Respiratory droplets
- Transcytose like Neisseria
- Encapsulated strains invade bloodstream
- Endotoxin: cell damage and local and systemic inflammation
List the 4 main clinical manifestations of H. influenzae Type b. (and slightly describe their sx)
- Meningitis
- Epiglottitis (fever, sore throat, stridor, cherry red)
- Cellulitis (purple erythema on cheek and periorbital)
- Septic arthritis (less common)
(Most of these occur in children 2-4, meningitis in children less than 2)
List the 3 main clinical manifestations on non-typable H. influenzae.
What’s the major difference w/this type of H influenzae vs. type b?
- Otitis media
- Sinusitis (chronic and acute)
- Bronchitis/COPD (chronic or acute)
- Has no capsule
What type of fluid would you want to obtain for a gram stain for H. influenzae?
CSF or joint fluid
What type of culture do you use for H influenzae? (chocolate or blood)
Chocolate
What 2 growth factors from blood does H. influenzae require?
X factor (Hematin) V factor (NAD)
Both supplied by lysed but not whole blood.
(Therefore, org doesn’t grow on blood agar)
What does bacilli mean?
Therefore, what does coccobacilli mean?
- Bacilli: rod-shaped
- Coccobacilli: intermediate b/w sphere and rod-shaped
What test would you use to prove it’s H influenzae rather than another type of hemophaelis?
Factor X and V strips.
What’s the current treatment for H. influenzae in its severe form?
Broad spectrum cephalosporins (2nd and *3rd)
Ampicillin used to work
What is the H influenzae vaccine conjugated to?
Diphtheria toxoid
For what 2 bacteria is rifampin used for prophylactic treatment of close contacts?
- H. influenzae
- N. meningitidis
What does bortadella cause?
Pertussis, or whooping cough
Is bortadella gram pos or neg?
What shape is it?
- Gram-negative
- Coccobacillis
What toxins are a/w bortadella? (4)
Does it have a capsule?
- Pertussis toxin (PT)
- Tracheal cytotoxin (PG fragment)
- Dermonectrotic toxin
- LPS endotoxin
No capsule
What does the tracheal cytotoxin of bortadella cause?
Causes extrusion of ciliated tracheal epithelial cells
What does the dermonectrotic cytotoxin of bortadella cause?
Ischemic necrosis
List the adhesins that bortadella has a/w it.
- Pertactin (surface ptn)
- Filamentous hemagglutinin (Fha) (promotes intracellular survival)
- Pertussis toxin AB toxin (B is adhesin)
- Pili
Recall: how does the AB subunit of Bortadella pertussis toxin work?
- What are the biologic effects?
- AB subunit: A-S1 enzymatic, B-S2-S5 binding
- A - ADP-ribosylation of regulatory G protein.
Prevents inactivation of adenylate cyclase + increase in cAMP - Biologic effects: increased respiratory secretions and mucus production; lymphocytosis
B – Subunits – adhesion to cell membrane
How is bortadella pertussis transmitted?
What is the reservoir?
Respiratory droplets
- Adults
How was bortadella affected by immunization changes?
Decreased immunization = increased infections recently
Diagnose pertussis from a clinical description.
- 7-10 day incubation period
- 1-2 weeks of runny nose, malaise, fever, anorexia (catarrhal phase, flu-like sx)
- 2-4 weeks of whooping cough, vomiting, leukocytosis (paroxysmal phase)
- 3-4 weeks+ of diminished cough, 2ndary complications (PNA, seizures, encephalopathy) -convalescent phase
What lab abnormality is seen in bortadella pertussis?
Where do you get the sample from?
What type of blood agar does it grow in?
What’s the best way to ID it?
- Leukocytosis
- Nasopharyngeal aspirate
- Chocolate
- PCR
What’s the best antimicrobial to treat bortadella with?
Azithromycin
- Eliminates nasopharyngeal organisms and prevents spread
What’s the name of the vaccine for pertussis for children?
Adults?
DTaP Vaccines
- Tdap recommended for all adults (replace every 10 years)
