Gram- Rods Causing Respiratory Disease, Zoonotic, Opportunisitc

Question 1

what is the morphology of Haemophilus influenzae and what are its special growth requirements?

Answer 1

slender, pleiomorphic Gram- rods

grow on chocolate agar only - require NAD and hemin (found in RBC)

Question 2

where does Haemophilus influenzae (Gram- rod) colonize, how does it spread, and what are its virulence factors (3)?

Answer 2

only infects humans
unencapsulated/non pathogenic colonizes upper respiratory tract

pathogenic spread via respiratory route, contain:
1. capsule
2. IgA protease
3. iron acquisition mechanisms

may spread locally from URT to middle ear (otitis media), sinuses (sinusitis), and lungs (pneumonia)… can also cause epiglottitis, meningitis, septic arthritis

Question 3

what is the vaccine for Haemophilus influenzae? (Gram- rod)

Answer 3

Hib conjugate vaccine: capsular polysaccharide conjugated to diphtheria toxin

given to children beginning 2 months of age

Question 4

25% of Haemophilus influenzae (Gram- rod) produce beta-lactamase and therefore are resistant to ampicillin, but essentially all isolates are susceptible to 3rd generation ______

Answer 4

cephalosporins (cefotaxime)

Question 5

what bacteria does this describe?
- Gram- rod
- causes respiratory infection
- only colonizes/infects humans
- can only survive in environment for short periods
- produces small colonies on blood agar
- best diagnosed with NAAT (PCR)

Answer 5

Bordetella pertussis

Question 6

how does Bordetella pertussis (Gram- rod) spread, and what illness does it cause?

Answer 6

spreads via respiratory route (2 week incubation), highly infectious

causes cold-like prodrome followed by “whooping” cough

convalescence is slow (4-6 weeks)

Question 7

what are 3 adhesins important for Bordetella pertussis (Gram- rod) infection?

Answer 7

adhesins promote attachment and prevent phagocytic clearance

1. filamentous hemagglutinin: binds integrins on ciliated epithelial cells
2. fimbriae: undergo phase variation
3. BrkA protein: complement resistance

Question 8

what are 3 important toxins for virulence of Bordetella pertussis (Gram- rod)?

Answer 8

1. tracheal cytotoxin: stimulates IL-1 mediates killing of ciliated epithelial cells (which it binds to)
2. adenylate cyclase toxin: inhibits phagocyte function
3. pertussis toxin: systemic effects (lymphocytosis, sensitization to histamine, enhanced insulin secretion)

Question 9

which bacterial toxin causes lymphocytosis, which is an atypical finding for bacterial infection?
(typically bacterial infections cause granulocytosis)

Answer 9

Pertussis toxin (of Bordetella pertussis, Gram- rod): causes systemic effects - lymphocytosis, sensitization to histamine, insulin secretion

[remember that Bordetella pertussis also produces tracheal cytotoxin and adneylate cyclase toxin]

Question 10

what vaccine is available for Bordetella pertussis (Gram- rod)?

Answer 10

DTwP: Diptheria, Tetanus, whole cell Pertussis (3 component vaccine)

replaced by DTaP: Diptheria, Tetanus, acellular Pertussis

acellular component includes virulence factors (pertussis toxin)

Question 11

what bacteria does this describe?
- Gram- rod
- highly fastidious
- causes respiratory infection
- acquired from environmental source (water)
- mild form of disease is termed Pontiac fever

Answer 11

Legionella pneumophila

requires BCYE agar: buffer, charcoal, yeast extract, iron, cysteine, antibiotics

Question 12

what is the primary diagnostic tool for Legionella pneumophila (Gram- rod) infection?

Answer 12

urine antigen test (Serotype 1 infection)

Question 13

explain why it makes sense that Legionella pneumophila (Gram- rod) is very fastidious?

Answer 13

natural habitat is water, multiplies in amoebae (protozoan) host —> typically, intracelular bacteria are fastidious because they require host nutrients

in humans, multiples in macrophages and blacks phagosome/lysosome fusion

Question 14

all zoonotic bacteria are Gram ____ and shaped as ____ or ____

Answer 14

all zoonotic bacteria are small Gram- rods or coccobacilli

little or no human to human transmission

may require non-standard antibiotics, some are highly virulent, risk for bioterrorism

Question 15

describe the source of Brucella spp. (species) and the illness it causes

Answer 15

small Gram- coccobacillus (zoonotic), from livestock/unpasteurized dairy

—> systemic febrile illness

*significant threat to laboratory workers

Question 16

describe the source of Pasteurella multocida and the illness it causes

Answer 16

small Gram- coccobacillus (zoonotic), normal oral flora of domestic animals - infection associated with animal bites

—> rapidly progressive soft tissue infection, can disseminate widely

Question 17

describe the source of Francisella tularensis and the illness it causes

Answer 17

small Gram- coccobacillus (zoonotic), transmitted from wild animals (rabbits) via direct contact or insect vector

low infectious dose (3 organisms), high risk to lab workers, but little to no human to human contact

—> ulceroglandular (ulcer and lymphadenopathy), oculoglandular, oral/pharyngeal (contaminated food/water), respiratory infection (aerosol inhalation)

Question 18

what was the cause of bubonic plague? how is this bacteria transmitted?

Answer 18

Yersinia pestis: zoonotic Gram- rod

transmitted from rodent to human via flea bite

—> causes enlarged, ulcerated lymph nodes (effacement of lymph node, architecture destroyed)

Question 19

what special stain is used for Yersinia pestis (zoonotic Gram-)?

Answer 19

Wayson stain - causes “safety pin” appearance due to bipolar staining of bacteria

Question 20

what kind of bacteria is Pseudomonas aeruginosa?

Answer 20

Gram- rod with polar flagella, opportunistic

ubiquitous in environment, creates biofilms

Question 21

what bacteria does this describe?
- Gram- rod with polar flagella
- opportunistic and ubiquitous
- obligate oxidizer
- no acids from sugars on test media
- many isolates produces siderophores (pyoverdin)

Answer 21

Pseudomonas aeruginosa - produces biofilms

has many virulence factors: extracellular polysaccharide, pili, LPS, extracellular enzymes, Exotoxin A, Type III secretion system

Question 22

what kind of disease does Pseudomonas aeruginosa cause?

Answer 22

Gram- rod with polar flagella, opportunistic and ubiquitous

—> nosocomial infections (burn patients, intubated patients), otitis externa, hot tub foliculitis, chronic respiratory infection in cystic fibrosis patients

Question 23

which of these is most likely to infect blood products, given that it grows at low temperature?
a. Campylobacter jejuni
b. Yersinia enterocolitica
c. Shigella boydii
d. enteropathogenic E. coli

Answer 23

b. Yersinia enterocolitica: type of enteropathogenic Yersinia (as is Y. pseudotuberculosis)

travels from intestine to local lymph nodes
uses Type III system to inhibit phagocytosis, causes painful inflammation of lymph nodes

Question 24

which of these is a halophile that can cause diarrhea from eating raw fish or shellfish?
a. Vibrios vulnificus
b. Vibrio cholerae
c. Enterotoxigenic E. coli
d. Enteropathogenic E. coli

Answer 24

a. Vibrios vulnificus (also V. parahaemolytics): non-cholera Vibrios, common in natural waters, cause wound/soft tissue infections

remember that halophile = requires NaCl for culture

grows on TCBS medium (thiosulfate-citrate-bile salts)

Question 25

Which of these zoonotic bacteria is most likely to be found in unpasteurized dairy?
a. Pasteurella multocida
b. Brucella spp. (species)
c. Francisella tularensis
d. Yersinia pestis

Answer 25

b. Brucella spp. —> systemic febrile illness

Question 26

Which of these zoonotic bacteria is most to be acquired from domestic animals?
a. Pasteurella multocida
b. Brucella spp. (species)
c. Francisella tularensis
d. Yersinia pestis

Answer 26

a. Pasteurella multocida —> rapidly progressive soft tissue infection

Question 27

Which of these zoonotic bacteria is most likely to be transmitted via an insect vector?
a. Pasteurella multocida
b. Brucella spp. (species)
c. Francisella tularensis

Answer 27

c. Francisella tularensis - transmitted from wild animals (esp. rabbits) to humans via direct contact or insect vector

—> ulceroglandular, oculoglandular, oral/pharyngeal, repository illness