Gram Negative Pyogens (Neisseria, H. Influenzae, Bordatella)

Question 1

What are the four fastidious gram negative pyogens?

Answer 1

1) Neisseria gonorrheae
2) Neisseria meningitidis
3) Haemophilus influenzae
4) Bordetella pertussis

Question 2

What are the two pathogenic species of Neisseria?

Answer 2

1) N. gonorrhoeae
2) N. meningitides

Question 3

Gram negative organisms cause disease primarily through their production of _____ and the resulting host _____

Answer 3

Gram negative organisms cause disease primarily through their production of ENDOTOXINS and the resulting host IMMUNE RESPONSE

Question 4

Species of Neisseria are differentiated by their ability to _______

Answer 4

Use specific sugars for energy

Question 5

What sugars and pH indicator are placed into a broth to help differentiate N. gonorrheae and N. meningitidis in the lab?

Answer 5

Sugars: Glucose, maltose, sucrose, and lactose

pH indicator: Phenol red

Question 6

What sugars do N. gonorrheae and N. meningitidis ferment (use for energy)?

Answer 6

N. gonorrheae: ONLY glucose

N. meningitidis: Glucose AND maltose

Question 7

What are the two main structural differences between N. gonorrheae and N. meningitidis?

Answer 7

Encapsulation and amount of pili

N. gonorrheae: NO capsule, A LOT of pili

N. meningitidis: Thick CAPSULE, some pili (not as many as gonorrheae)

Question 8

How does Neisseria appear upon gram staining?

Answer 8

Gram negative

Non-motile

Diplococci

Usually in pairs

Question 9

T/F: Neisseria is capable of surviving for long periods in the external environment

Answer 9

FALSE

This is why it must be transmitted by close or intimate contact. It dries out in the environment

Question 10

Neisseria attach to _____ of mucosal surfaces via their pili and outer membrane surface proteins

Answer 10

Non-ciliated columnar epithelium

Question 11

T/F Both pathogenic species of Neisseria are phagocytosed as a part of their life cycle inside the host

Answer 11

FALSE

N. gonorrheae: Actively phagocytosed by PMNs → Remains localized → Generates pus

N. meningitidis: EVADES phagocytosis (capsule) → Enters blood stream → Sepsis

Question 12

What is the lab test that differentiates Neisseria for other organisms? How does it work?

Answer 12

Oxidase Test

1) Oxidase reagent placed on filter paper
2) Bacteria rubbed on top
3) Oxidase positive → Purple-blue (Neisseria!)
4) Oxidase negative → no color change

Question 13

What species of Neisseria is responsible for the STI gonorrhea?

Answer 13

N. gonorrheae

Duh

Question 14

What virulence factor of N. gonorrheae mediates attachment to other cells (sticking to a spermatozoa and moving up the female reproductive tract, e.g.)?

Answer 14

Pilin and Opa protein

Question 15

N. gonorrheae has 3 proteins that strip _____ from transferrin, lactoferrin, and hemoglobin that is used for survival of the organism

Answer 15

Iron

Question 16

What virulence factor of N. gonorrheae is an endotoxin with high activity that generates the pus characteristic of infection?

Answer 16

LipoOLIGOsaccharide

Question 17

What virulence factor of N. gonorrheae is found on mucosal surfaces and protects the organism?

Answer 17

IgA1 Protease

Question 18

What virulence factor of N. gonorrheae lends it its resistance to penicillin or other Beta-lactams?

Answer 18

Beta-lactamase

Question 19

Neisseria gonorrheae forms micro-colonies by attaching their pilito the microvilli of epithelial cells. After formation of the micro-colony, they exhibit _____, where the pili actively extend, grab another cell, and retract, moving the micro-colony across the cell surface.

Answer 19

Twitching motility

Question 20

T/F Women have a higher incidence of acquiring N. gonorrheae infectioTns from sexual contact

Answer 20

TRUE

The vagina and cervix have an 80% chance of infection after exposure, while the male urethra has only a 20% risk of infection after exposure

Question 21

The majority of N. gonorrheae cases occur in 15-29 year olds, and is associated with _____ and _____

Answer 21

Sexual activity

Lack of condom use

Question 22

What are the non-genital sites of N. gonorrheae infection?

Answer 22

Oropharynx, rectum, conjunctiva

Question 23

T/F N. gonorrheae in non-genital and genital sites of juveniles/childres is a sign of sexual abuse.

Answer 23

TRUE

Question 24

When infected with N. gonorrheae, males present with _____ 2 to 3 days after the sexual encounter with _____ and _____

Answer 24

Acute urethritis w/ severe dysuria and purulent dischagre

Question 25

T/F: Most females infected with N. gonorrheae present with a cervicitis and/or urethritis.

Answer 25

FALSE Most females infected with N. gonorrheae are asymptomatic Females presenting with symptoms typically do have cervicitis and/or urethritis though

Question 26

Why is there no effective vaccine against N. gonorrheae?

Answer 26

N. gonorrheae undergoes antigenic drift, changing their pili and outer membrane proteins (Opa) to avoid immune eradication

Question 27

Neonates who acquire gonorrhea from infected mothers often present with \_\_\_\_\_. Tx?

Answer 27

Neonatal ophthalmia Tx: Abx eye drops

Question 28

A very small percentage of N. gonorrheae infections lead to bacteremia. What are the two characteristic features of the disseminated infection?

Answer 28

1) Painful hemorrhagic lesions on the hands 2) Septic arthritis (usually knees - can culture from pus of infected joints)

Question 29

How can N. gonorrheae cause an ectopic pregnancy (a life threatening condition)?

Answer 29

Untreated → ascends female GU → to fallopian tubes → Inflammation damages tubal cilia → Egg isn't pushed along normally → Egg trapped and fertilized ectopically

Question 30

What are the symptoms of Gonorrhea?

Answer 30

2-7 Days after exposure: Burning/itching during urination w/ thick yellowish discharge from penis or vagina Polyuria/Increased frequency Swelling/redness of urethral opening Vulvar itching/burning/pain Etc

Question 31

What is the special agar used to culture N. gonorrheae? What components of the agar select against other organisms?

Answer 31

Thayer-Martin VCN Agar (Chocolate agar) * Vancomycin selects against G(+) organisms * Colistin selects against G(-) organisms * Nystatin selects against fungi After other organisms are selected against, oxidase reagent is added to see if N. gonorrheae is there

Question 32

What test that is not a culture looks for the presence of both N. gonorrheae and Chlamydia DNA? It has largely replaced VCN/Chocolate agar

Answer 32

Nucleic acid amplification test (NAAT)

Question 33

What is the treatment of N. gonorrheae infxn? What organism is treated at the same time?

Answer 33

IM Ceftriaxone + Oral azithromycin or oral doxycycline Azithromycin treats Chlamydia also

Question 34

What is the morphologic feature of N. meningitidis that distinguishes it from N. gonorrheae?

Answer 34

Presence of polysaccharide capsule. Virtually indistinguishable on media/Gram staining

Question 35

What serogroup of N. meningitidis causes the majority of meningococcal disease? What forms the basis of meningococcal serogrouping in addition to group specific immunity?

Answer 35

Group D Polysaccharide capsule tested for serogrouping and is the basis for group specific immunity

Question 36

What is the exception to the rule that meningococcal capsule serogroups confer specific immunity? Why?

Answer 36

Group B Its sialic acid polymer is recognized as "self", resulting in little immunity to Group B meningococci and little autoimmune damage

Question 37

There is an inverse correlation between _____ and meningococcal disease

Answer 37

Humoral immunity High incidence in kids \< 2 y/o: Immature immune systems Decreases in incidence as they acquire antibodies thru vaccination Small increase in incidence at about 20 y/o: Need booster/in close proximity to those without vaccination

Question 38

T/F: N. meningitidis only causes disease in a specific age group

Answer 38

FALSE N. meningitidis causes can seriously infect humans of all ages

Question 39

How is N. meningitidis transmitted?

Answer 39

Respiratory droplets or direct contact with nasopharyngeal secretions

Question 40

After colonizing the \_\_\_\_\_, N. meningitidis invades the \_\_\_\_\_. If the patient does not have protective antibodies (not vaccinated), the organism may then get into the _____ and disseminate

Answer 40

1) Colonization of nasopharynx 2) Invasion of epithelial lining 3) No vaccination/Abs: Gets into the bloodstreat and disseminates to tissues (Meninges)

Question 41

N. meningitidis can shed its outer membrane, releasing blebs/vesicles that are rich in \_\_\_\_\_. What are the consequences of this?

Answer 41

Rich in LOS (endotoxin) If released throughout the body, the endotoxins generate a huge cytokine response that cause a lot of problems (micro-clots, shock, e.g.)

Question 42

Meningococcemia presents as ______ that develop within 1-2 days

Answer 42

Flu-like symptoms (fatigue, vomiting, cold hands/feet, chills, severe myalgia, joint pain, pain in chest/abdomen, rapid breathing, diarrhea)

Question 43

What is the characteristic physical findings in late stage disseminated meningococcemia?

Answer 43

* DARK PURPLE RASH that may be seen all over the body (vs. GC's rash appearing only on the hands) * Appears as a trasient macular/papular rash on upper chest and face * Purpura from EARLY DIC COAGULATION due to septicemia forming grey-black areas on *infarction* * Progression leads rapid enlargement of lesions → ISCHEMIC NECROSIS AND GANGRENE * Ischemia can be focal or within entire extremity (amputate)

Question 44

Bilateral infection by N. meningitidis and necrosis of adrenal glands causing a lethal adrenal insufficiency (5-15% of pts with meningococcemia) is known as \_\_\_\_\_

Answer 44

Waterhouse-Friedrichsen Syndrome

Question 45

\_\_\_\_\_ is a medical emergency characterized by the *sudden* onset of fever, headdace, stiff neck, nausea, vomiting, photophobia, altered mental status due to N. meningitidis infection. How is diagnosis accomplished?

Answer 45

Meningitis Diagnosed by lumbar puncture of purulent CSF for gram staining

Question 46

Which polyvalent meningitis vaccine is very effective in young adults, is non-conjugated, and is a freeze dried mixture?

Answer 46

MENOMUNE - MPSV4

Question 47

Which polyvalent meningitis vaccine is administered to patients who can't make antibodies to N. meningitidis capsule, and is composed of 4 serogroups conjugated to diphtheria toxoid?

Answer 47

MENACTRA - MCV4

Question 48

Exposure prophylaxis of meningococcal meningitis is administered within 24 hours of close contact w/ infected individuals and includes _____ + _____ +/- \_\_\_\_\_

Answer 48

Oral rifampin and ciprofloxacin + parenteral ceftriaxone +/- booster shot

Question 49

The presence/absence of a _____ determines the spectrum of disease caused by H. influenzae

Answer 49

Capsule

Question 50

What diseases are caused by encapsulated/non-encapsulated H. influenzae?

Answer 50

* _Encapsulated_: *Meningitis*, epiglottitis, cellulitis, conjunctivitis (aegyptius) * _Non-encapsulated_: Otitis media, bronchitis/bronchopneumonia

Question 51

How is H. influenzae transmitted?

Answer 51

Respiratory/droplet inhalation

Question 52

How is infection by H. influenzae prevented?

Answer 52

* PRP conjugate vaccine * Rifampicin prophylaxis

Question 53

What two factors are required to grow H. influenzae in the lab? What agar has these factors?

Answer 53

* Hemin (Factor X) + NADH (Factor Y) * Chocolate agar contains RBC that, when lysed, release both of these factors.

Question 54

What is the major pathogenic serotype of H. influenzae? What diseases can it cause?

Answer 54

* Encapsulated HiB * *Meningitis -* Requires dissemination into bloodstream * Sx similar to those of other meningitides but with fewer petechial lesions * Cellulitis - local invasion of skin * Epiglottitis - obstructs air flow, may need cricothyrotomy

Question 55

Post infectious sequelae of HiB occur in 1/10 infected infants. What are some of them?

Answer 55

* Blindness * Deafness * Obstructive hydrocephalus * Mental retardation * Poor reading/language skills

Question 56

What drug is used as to prevent HiB infection in immune & non-immune household members?

Answer 56

Rifampicin

Question 57

What H. influenzae biotype causes conjunctivitis?

Answer 57

Aegyptius

Question 58

If trapped in specific locations, nonencapsulated H. influenzae causes local disease such as _____ and \_\_\_\_\_

Answer 58

* Otitis media * Bronchopneumonia/Bronchitis

Question 59

What is the major virulence factor of H. influenzae?

Answer 59

Capsule

Question 60

What virulence factor of H. influenzae functions in attachment?

Answer 60

Outer membrane proteins/Pili

Question 61

What virulence factor of H. influenzae is an endotoxin that causes ciliary stasis in respiratory epithelium and endotoxin shock?

Answer 61

Lipo-oligosaccharide

Question 62

What virulence factor of H. influenzae protects the organism at mucosal sites?

Answer 62

IgA-ase

Question 63

The PRP vaccine most effective against HiB is a Type B capsular antigen containing what three components?

Answer 63

* Pentose sugars * Ribose * Ribitol phosphate

Question 64

What gram negative pyogenic organism causes whooping cough?

Answer 64

Bordatella pertussis

Question 65

What vaccine is administered to provide immunity against Whooping Cough (B. pertussis)

Answer 65

DTaP aP = acellular pertussis

Question 66

Attachment of B. pertussis to cilia of respiratory epithelium is mediated by \_\_\_\_\_, \_\_\_\_\_, and \_\_\_\_\_

Answer 66

* Pili * Filamentous hemagluttinin * Pertactin

Question 67

After attachment of B. pertussis to respiratory epithelium cilia, what two chemicals are made that injure the ciliated epithelium? Additional injury is from the peptidoglycan fragments of what toxin?

Answer 67

* Pertussis toxin * Adenylate cyclase * Additional injury: Tracheal cytotoxin (TCT)

Question 68

After damage from the toxins and adenylate cyclase of B. pertussis, the mucosa is _____ and pertussis toxin \_\_\_\_\_

Answer 68

* Mucosa is denuded without protective cilia * Pertussis toxin enters the bloodstream to act systemically

Question 69

The first stage of B. pertussis infection is characterized by _____ and \_\_\_\_\_.

Answer 69

* Attachment to respiratory epithelium * Cold like symptoms (slight cough, runny nose, low grade fever)

Question 70

In the first stage of B. pertussis infection, the organism is slightly \_\_\_\_\_, and is responsive to \_\_\_\_\_

Answer 70

* Slightly infectious * Responsive to abx (azithromycin)

Question 71

What stage of B. pertussis infection is highly infectious, with the bacteria being expelled to the environment via a productive cough that produces thick mucus?

Answer 71

Second (Catarrhal/Commuicable) stage

Question 72

The death of epithelial cells in the second/catarrhal stage of B. pertussis infection increases risk of \_\_\_\_\_

Answer 72

Secondary infection

Question 73

What stage of B. pertussis infection produces the characteristic "whooping" cough?

Answer 73

Third / Paroxysmal Stage

Question 74

T/F The second stage of B. pertussis infection is susceptible to abx (azithromycin)

Answer 74

TRUE

Question 75

What are the caracteristic features of the third stage of B. pertussis infection?

Answer 75

* Whooping cough * Leukocytosis * Hypoglycemia * Unresponsive to abx * Danger to infant posed by inability to clear secretions and maintain nutrition

Question 76

What stage of B. pertussis infection is characterized by a diminished cough, a hypoglycemic state, and a lymphocyte count that returns to normal?

Answer 76

Fourth/Convalescent stage

Question 77

What are the consequences of the Fourth/Convalescent stage of B. pertussis infection?

Answer 77

* Secondary bronchopneumonia * Acute encephalopathy * Convulsions/Brain damage * Generation of protective immunity