L3 MHD: Niesseria/Hemophillus/Bordetella Flashcards
Neisseria, Haemophilus and Bordetella are all gram ____________
Gram Negative
Neisseria – Key Characteristics
- Gram Negative ____________ (shape)
- Oxidase +/-?
- Differentiated by their _____________ reactions
- Gonorrhae oxidizes __________
- Mening oxidizes _________ & __________ - Increased susceptibility if ____________ deficiency
Two key virulence factors (VFs) of N. Meningitidis: _________ & _________
Two key VFs of N. Gonorrhoeae: _________ & ____________
- Gram Negative Diplococci
- Oxidase +
- Differentiated by their oxidation reactions
- Gonorrhae oxidizes glucose
- Mening oxidizes glucose & maltose - Increased susceptibility if complement C5-C8 deficiency (genetic deficiency)
Two key VFs of N. Meningitidis: LPS & Capsule
Two key VFs of N. Gonorrhoeae: Pili & OMPs (gonorrhea- OMPs- think “ow my penis”)
both have capsules & LPS, it’s just more important for N. meningitidis’s virulence
Neisseria meningitidis - Key Virulence Factors
- Pili- ____________
- A post-translational modification of pili helps meningitis do what? - Polysaccharide Capsule
- How many serogroups?
- Which ones are relevant to humans (5 groups)?
- Which one is not immunogenic?
Polysaccharide capsule is an especially important virulence factor for
a. ____________ invasion & __________
b. __________ penetration
- LPS
Helps cause cell _________ and systemic __________ which produces _______-like symptoms
- Pili- attachement (usually to nasopharynx cavity)
- Post translational modification of type 4 pilus helps with dispersement of virus - Polysaccharide Capsule
- 13 Serogroups
- A,B,C,Y,W-135 are important to humans
- Group B is non-immunogenic (does not produce an immune response)
Polysaccharide capsule:
- Bloodstream invasion and survival- prevents phagocytosis
- CNS penetration- important cause of meningitis- has tendency to cross BBB
- LPS
Helps cause cell damage and systemic inflammation- septic like symptoms
Pathogenesis of N. Meningitidis
- Enters thru _________
- Attaches to ciliated or non-ciliated cells of the _____________
- Multiples and alters ___________
- Transcytosis to _________ space
- Enters ____________ to cause __________ infection
Enters through nasal cavity
Attaches to cells of the respiratory tract
Multiplies and alters pilus which allows for dispersement (to environment to infect other people and to the submucosal space)
Transcytosis to submucosal space
Enters bloodstream to cause disseminated infection
Epidemiology of Meningococcal Disease
Developed world:
- Who is most at risk for the disease?
- Cases are most likely…?
- Men who have sex with men or a college campus outbreak is an example of an outbreak in ________ populations- what group of meningitis usually causes this?
Developing World:
-Usually outbreaks of Group _____ or ________
Disease is spread by ______________ _____________ & there is a 1,000 fold increase in attack rates in _________ contacts
Developed world:
- Children under 5 or teens/young adults are most at risk
- Most cases are sporadic and isolated
- MSM & College campuses may have a closed population outbreak- Group B Meningitidis causes this
- Rarely community outbreak of group A
Developing World:
-Usually community outbreaks caused by Group A or W-135
(Examples of this are the meningitis belt in Sub-Sahara Africa that affects infants or people on a pilgrimage to the Mecca)
Transmitted by Respiratory droplets; household contacts are 1000 times more likely to get the disease
Clinical Manifestations of Neisseria meningitidis Infection
Respiratory _________ followed by overt disease or transient carrier state
Symptoms of Meningococcemia: 1. 2. 3. 4. Key skin symptom is \_\_\_\_\_\_\_\_\_\_\_\_
Meningitis Symptoms: 1. 2. 3. 4. Key skin symptom is \_\_\_\_\_\_\_\_\_\_\_\_\_
Another clinical manifestation is urethritis, which is typically seen in which patient population?
Respiratory colonization (usually in nasopharynx)
Symptoms of Meningococcemia:
- Shock
- Hemorrhage
- Adrenal Hemorrhage- unable to respond to inflammatory stimulus (WATER-HOUSE Friedrickson)
- Purpura (serious symptom- patients who present with this usually do not survive)
Meningitis Symptoms:
- Headache
- Change in mental status
- Neurological symptoms
- Petecheae–>Purpura
Urethritis is typically seen in MSM
Laboratory Diagnosis: Neisseria meningitidis
Cultures can be taken from:
1.
2.
3.
Cultures are…
- Oxidase +/-?
- Able to oxidize what sugars?
- What media do they grow best on?
- Their growth is enhanced by what?
Gram stain- CSF
Cultures can be taken from:
- CSF
- Blood (toxic granulation- seen when magnitude of bacteremia is tremendous- specimen may look like a basophil under the microscope- it is really an immature neutrophil that has phagocytosed a bacteria particle)
- Skin (usually not likely to recover it from skin)
Cultures are…
- Oxidase +
- Oxidize glucose and maltose
- Nonselective growth on blood or chocolate agar
- Growth is enhanced by CO2
What is the best way to treat Neisseria Meningitidis?
What other drugs can be used?
What antibiotics are given as a prophylactic measure to household contacts?
Penicillin – resistance is uncommon
- Ceftriaxone- DRUG OF CHOICE because it penetrates the BBB better than penicillin G
- Can use penicillin G if sensitive
- Other cephalosporins can be used
Treat Household contacts with:
- Rifampin
- Ciprofloxacin
- Ceftriaxone (1 dose)
N. Meningitidis Vaccination
Vaccine – polysaccharide containing Groups \_\_\_\_, \_\_\_\_, \_\_\_\_, and \_\_\_\_\_\_\_ conjugated to diphtheria toxoid Vaccine Recommended For: 1.\_\_\_\_\_\_\_\_\_\_\_ 2.\_\_\_\_\_\_\_\_\_\_\_ 3.\_\_\_\_\_\_\_\_\_\_\_ 4. \_\_\_\_\_\_\_\_\_\_\_ 5.\_\_\_\_\_\_\_\_\_\_\_ 6.\_\_\_\_\_\_\_\_\_\_\_ 7.\_\_\_\_\_\_\_\_\_\_\_
New Serogroup ____ Vaccine
-Recombinant protein vaccine that is recommended to who?
-Vaccine contains Groups A, C, Y, W-135
Vaccine Given to/Recommended for:
- All Adolescents age 11-12
- College Freshmen living in dorms
- Microbiologists who are routinely exposed
- Populations in which an outbreak occurs (MSM)
- Military recruits
- Persons with increased susceptibility (asplenia, terminal complement deficiency)
- Travelers in hyperendemic regions (sub-sahara, saudi arabia)
New Serogroup B vaccines (MenB-FHbp, MenB-4C)
- Recommended for very high risk only
- i.e. patients who have had splenectomies
The two main disease states Meningoccus causes are what?
- Severe sepsis
- meningitis
Polysaccharide capsule and LPS are most important in causing these disease states
Key Characteristics of Neisseria gonorrhoeae
- What are the two main adhesins?
- What two factors contribute to antigenic diversity?
- What is the most common way gonorrhoeae is spread? Is it symptomatic or asymptomatic?
- What areas of the body are most commonly infected in men? Women?
- Where is the disease most commonly disseminated to?
- What is the most common lab test(s) for diagnosis?
- What is the most effective treatment for gonorrohaea? How is it administered?
- Adhesins: pili, Opa
- Antigenic diversity: pili(recombination ability), Opa(on-off switch)
- Intimate sexual contact, asymptomatic reservoir
- Urethra (men), cervix (women), other exposed sites (throat or anus); there’s local spread to prostate, epididiymis, fallopian tube
- Joints & skin
- Gram stain (90+% from male urethra), culture, PCR
- Ceftriaxone- injected; no oral therapy
What are 4 virulent factors of Neisseria gonorrhoeae that are found on the outer membrane? What do they do? 1. 2. 3. 4.
- Pili – stacked units of repeating protein (MW 19 kD)
- PorB– Porin
Pores (channels) that facilitate epithelial cell invasion - Opa – adherence proteins confer opaque appearance to colony
-Opaque: localized disease
-Transparent: disseminated disease - Rmp proteins – stimulate blocking antibodies
Antigenic Variation in Pili and Opa in Neisseria gonorrhoeae
Pili: use DNA ________ involving transfer of variable sequences form ______ to _______
Opa:
How many different Opa genes in genome?
How is the gene turned on?
Pili
-DNA recombination involving transfer of variable sequences from unexpressed (silent) loci, pilS, to expression locus, pilE
Opa – Up to 11 different Opa genes in genome
- Switch on an off Opa genes by varying length of 5 nucleotide (CTCTT)n repeats in the leader sequence encoding the Opa gene
- Alteration in number or repeats turns on or off expression
Epidemiology of Gonorrhea
Transmission occurs by what type of contact?
What age group is most at risk?
What percent of women are asymptomatic? What percentage of men?
What is the likelihood a man who has sex with an infected woman will get the disease? A woman who has sex with an infected man?
- Transmission across mucosal surfaces by direct contact
- High rate among adolescents and young adults
Asymptomatic: 50% women, 5+% men
Risk
Men 20% per contact with infected woman
Women 50% per contact with infected man
Pathogenesis of Gonorrhea- Invasion & Damage
- Adherence
What structures do pili attach to? Opa? - Epithelial cell invasion involves what outer membrane protein?
- LOS & Peptidoglycan fragments promote what response in the host?
- What deeper male/female structures does the disease spread to?
- Attachment:
- Pili - urethral, vaginal, fallopian tube, sperm, neutrophils
- Opa – cervical, urethral and other gonococcal cells (mediates adherence to various tissues of the genital tract) - Epithelial cell invasion involves Por B, other proteins
- LOS & Peptidoglycan promote inflammatory response and damage
- Deeper male structures affected: epididymus, prostate
- Female structures: paracervical glands, fallopian tubes (carried here by sperm) which may cause pelvic inflammatory disorder
- -Serum resistant strains invade bloodstream and disseminate
What 5 ways does Neisseria Gonorrhoeae evade the immune system?
- Antigenic and phase variation
- Resists phagocytosis (opa & pili)
- Binds host transferrin, lactoferrin–>iron; increases iron acquisition which is a growth factor
- IgA protease- prevents immune response at mucosal surfaces
- Evades serum antibody and complement system via LOS sialylation and Rmp stimulating blocking antibodies (protects other surface antigens- Por, LOS)
Gonorrhea can present as a primary (localized) or secondary disease (local invasion/disseminated)
What are the 5 signs of primary disease?
What are the 4 signs of secondary disease?
Primary disease:
- Cervicitis (females)
- Urethritis (males)- purulent discharge/burning urination
- Proctitis (MSM)
- Pharyngitis (sore throat from oral)
- Conjunctivitis (newborns born to infected mothers/sexual contact)
Secondary:
- Epididymitis/Prostatitis
- Endometritis/salpingitis (PID)
- Arthritis (seen in joints)
- Tenosynovitis- seen on the dorsal side of the wrist
- Septic Arthritis- example: one knee affected- drain knee to find purulent fluid with gonorrhea present - Dermatitis (skin lesions- usually on lower extremities)
Lab Diagnosis of Neisseria gonorrhoeae
Gram Stain- get sample from where?
Why is it less sensitive in women?
Culture: gonorrhoeae is ____________, and therefore requires _____________ and _____ for growth
- Oxidase +/-?
- What sugar does it oxidize?
What test is done that can directly detect gonorrhea from clinical specimens, including genital, oral, anal AND urine?
What is a problem with this test?
Gram stain: urethra, cervix, joints
-95% sensitive from male urethra, only 50-70% sensitive from uterine cervix due to competing vaginal flora that can make it hard to identify
Culture: gonorrhea is fastidious, requires chocolate agar and CO2 for growth
- Oxidase +
- ONLY oxidizes glucose
Nucleic acid amplification is a way to directly detect disease from clinical specimens (including urine)
-Downfall: does not test for abx susceptibility
What is the best treatment for gonorrhea?
How is it administered?
What drug is given in conjunction to gonorrhea abx?
What other drugs can be used?
Is the drug sensitive or resistant to penicillin? (Two reasons why)
Ceftriaxone is the best treatment- there is no oral treatment (usually give pt an injection)
-Given with azithromycin (for C. trachomatis)
Patient can also be given Doxycycline for C. Trachomatis but the course of course of treatment is longer (7 days vs. one dose)
Penicillin Resistant
- Decreased affinity of Pen for PBP (low level)
- Plasmid mediated TEM type Beta Lactamase (high level)
Haemophilus influenzae Characteristics
- Gram (-) _________
- Serotypes: grouped _____ by ___________
Which type is most important? - Biotypes: using three biochemical reactions- used epidemiologically or clinically?
- What is an example of an H. influenzae biogroup?
- Gram-negative coccobacilli
- Serotypes: a-f by polysaccharide capsule (similar to the polysaccharide capsule of N. meningitidis and gonorrhoeae)
- Type B serotype is most important - Biotyping is for epidemiological studies only
- Biogroup Ex: H. influenzae biogroup aegyptius causes Brazilian purpuric fever
Haemophilus influenzae: What are the 3 main Antigenic Structures?
- Polysaccharide capsule
- 6 types: a - f
- Type B - polyribitol phosphate-
- Antibody protective - Pili (adherence)
- Endotoxin (LPS)
Haemophilus influenzae Type B: Epidemiology
- What group is most at risk?
- What has caused a 94% decline in this disease in the developed world?
- Where is H. influenzae still a problem?
- What is the risk of a child under the age of 4 getting this disease in an unimmunized household?
- Children 6 months to 2 years
- Meningitis, septicemia, cellulitis
Haemophilus influenzae: Pathogenesis
Transmitted by rep. droplets
Adheres by pili and OMPs
Transcytose like Neisseria
Encapsulated strains invade bloodstream- not phagocytosed until specific Ab formed
Endotoxin causes local and systemic inflammation
Haemophilus influenzae type B: Clinical Manifestations
- How do children under 2 typically present?
- Children 2-4 have what 3 symptoms? What is unique about them?
Children
Nontypable Haemophilus influenzae causes what three things?
Otitis media
Sinusitis - acute and chronic
Bronchitis - esp. COPD- increases purulent secretions, and lower resp. tract infections
Strep pneumo is #1 cause of otitis media & sinusitis, nontypable haemophilus influenzae is the second most common cause
Diagnosis: Haemophilus influenzae
Gram stain- where do you take sample from?
Culture -
-Agar?
Require growth factors from blood:
1.
2.
Gram stain: CSF, joint fluid
Agar: chocolate agar, Nonmotile, non-sporeforming
Req. GFs from blood:
1. X factor (Hematin)
2. V factor (NAD)
Both supplied by lysed but not whole blood
X & V strips used to test, need both V AND X factor to grow! Chocolate agar provide these!
Treatment: Haemophilus influenzae
Antibiotic therapy: What is the preferred antibiotic for severe disease?
What do you give for less severe disease? (Sinusitis, otititis)?
What is the chemoprophylaxis treatment of household contacts?
Abx therapy:
Severe disease
Broad spectrum cephalosporins (2nd and 3rd) are used since 25-50% of strains produce beta-lactamases (ampicillin resistant)
Less severe: oral abx
- Amoxicillin/clavulanate
- Trimethoprim-sulfamethoxazole
- Fluoroquinolones
Give household contacts Rifampin
Prevention: Haemophilus influenzae
What is the vaccine made up of?
When and to whom is the vaccine given?
Vaccine: PRP-protein conjugate vaccines
-T-cell dependent antigens- present in very young babies
Universal vaccination of children
-Age 2 months- 4 doses
Endocarditis is associated with what two haemophilus species?
Chancroid, an STD, is caused by what species?
Endocarditis:
- H. (Aggregatibacter) aphrophilus
- H. parainfluenzae
Chancroid :
- H. ducreyi
Bordetella pertussis
Morphology?
What are the two most important species?
Gram-negative coccobacilli
0.5-1.0um
Two most important species:
- B. Pertussis (causes pertussis)
- B. Parapertussis (causes a milder form of pertussis)
Bordetella pertussis Key Characteristics
-Capsule?
-Adhensins?
-What are the 5 toxins it produces? What is the major virulent toxin?
(HINT: Dat PE makes me cough)
No Capsule
Has many adhesins
5 Toxins:
- D- Dermonecrotic Toxin
- A- Adenylate Cyclase Toxin
- T- Tracheal Cytotoxin (peptidoglycan fragment)
- P- Pertussis Toxin- MAJOR virulence toxin
- E- Endotoxin (LPS)
Bordetella pertussis: Adhesins
Pertactin (surface protein) and Filamentous hemagglutinin (Fha ) both bind to:
- ________ on membranes of ciliated respiratory cells
- _______ glycoprotein on macrophages, which promotes intracellular survival
Pertussis Toxin-
What does the S2 subunit bind?
What does the S3 subunit bind?
Pili (promote adhesion)
Pertactin and Fha
- Both bind to integrins (both have the Arg-Gly-Asp sequence that promotes binding to Integrins) on membranes of ciliated respiratory cells
- Both bind to CR3 – glycoprotein on macrophages that promotes phagocytosis without respiratory burst
Pertussis toxin
- S2 (binding) subunit binds to glycolipid on ciliated cells
- S3 binds to receptors on phagocytic cells–>expression of CR3 on surface
What is the major virulence factor in pertussis?
What is the main function of its A-S1 Subunit? Its B-S2-S5 subunits?
Pertussis Toxin - PT
AB subunit: A-S1 enzymatic, B-S2-S5 binding
A Subunit A-S1:
- ADP-ribosylation of regulatory G protein
- Prevents inactivation of adenylate cyclase (increased cAMP)
- Biologic effects of increased cAMP: increased respiratory secretions and mucus production; lymphocytosis
-B Subunits S2-S5: previously discussed adhesions
What do the following toxins do to promote pathogenesis of Bordetella pertussis?
Adenylate Cyclase Toxin ?
Tracheal cytotoxin?
Dermonecrotic toxin?
Adenylate Cyclase Toxin:
- increase cAMP levels in cells
- affects leukocyte fxns- chemotaxis/superoxide production
Tracheal cytotoxin:
- Peptidoglycan fragment that causes extrusion of ciliated tracheal epithelial cells
- Stimulates IL-1 release
Dermonecrotic Toxin:
-Causes ischemic necrosis
Bordetella pertussis: Epidemiology
How is it spread?
How does the disease present in adults?
What has the immunization trend been regarding this disease?
VERY CONTAGIOUS!
Spreads by airborne droplets
Disease is unrecognized in adults- they’re reservoirs (don’t get whooping cough symptoms children get)
-There has been decreased immunization leading to increased incidence (thanks Jenny McCarthy)
Describe the Pathogenesis of Pertussis… does it invade respiratory tract cells?
What is the pathogenesis of symptoms?
- Attach to ciliated cells by adhesins
- Tracheal cytotoxin and others destroy ciliated cells
- Pertussis Toxin causes systemic manifestations, mucus production, cough, lymphocytosis
B. pertussis DOES NOT invade respiratory tract cells
Symptoms:
Flu-like–>COUGH–>(complications) pneumonia, CNS
Described as 100 day cough
Bordetella pertussis: Laboratory Diagnosis
What is the standard test?
What type of sample is used?
What medium does pertussis grow on?
- Aerobic or anaerobic?
- Motile or non-motile?
- Easy or hard to grow?
- Time sensitivity?
What are two other tests that can be used to detect pertussis? Which is performed in LUMC lab & state labs?
PCR is standard test
-Sample - nasopharyngeal aspirate
Medium: Charcoal blood agar
- Strict aerobe, non-motile
- Difficult and slow to grow
- Early- higher yield of growth
Tests to Detect:
- Antigen detection - direct immunofluorescence
- PCR – performed in LUMC lab and state laboratories
What antibiotic is used to treat pertussis?
Alternatives?
When is it effective?
What does it eliminate?
Main Abx: Azithromycin (other macrolides)
Alternate -Trimethoprim/sulfamethoxazole
Azithromycin is effective in catarrhal stage (1-2 weeks) only
-Abx eliminates nasopharyngeal organisms and prevents spread
Bordetella pertussis: Prevention
DTaP:
Who is it recommended for?
Tdap:
Who is it recommended for?
DTaP Vaccines:
- Purified, detoxified PT, Fha, Pn and Fim types 2 and 3
- Recommended for all children
- Replace killed whole cell vaccines
Tdap:
- Recommended for all adults
- Takes place of one routine (every 10 years) Td
Subunit vaccine: DTaP (infant), Tdap (adolescent adult)
