Gram Negative Bacilli

Question 1

Major gram negative group oxidase negative

Answer 1

Enterobacteriaceae

Question 2

Risk factors for typical pneumonia caused by pseudomonas aeruginosa

Answer 2

Chronic granulomatous disease

Cystic fibrosis

Question 3

Virulence factors of pseudomonas aeruginosa

Answer 3

Endotoxin ▶️ shock in septicemia
Pseudomonas exotoxin A ADP ribosylates eEF-2 ▶️ (-) elongation in protein synthesis
Capsule/slime layer ▶️ pulmonary microcolonies ▶️ hard to phagocyte

Question 4

Principal mechanisms of pseudomonas aeruginosa antibiotic resistant

Answer 4

Intrinsic resistance ▶️ loss affinity by porin (drug entry)
Plasmid-mediated B-lactamases
Acetylating enzymes

Question 5

Triad clinically seen in legionnaires disease. Important virulence factor of the microorganism and other disease caused by it.

Answer 5

Atypical pneumonia
Hyponatremia
Diarrhea

Facultative intracellular
Endotoxin

Pontiac fever

Question 6

Different presentations of tularemia and how is transmitted each one?

Answer 6

Ulceroglandular disease ▶️ tick bite (dermacentor), traumatic implantation skinning rabbits
Pneumonia ▶️ skinning rabbit (aerosols)
GI disease ▶️ “typhoidal tularemia”: undercooked or infected meat, contaminated water

Question 7

Toxins of bordetella pertussis

Answer 7

Adenylate cyclase toxin
Pertussis toxin
Endotoxin
Tracheal toxin

Question 8

Complication of whooping cough

Answer 8

Seizures
Encephalopathy
Pneumonia

Question 9

What do you use to diagnose brucellosis?

Answer 9

Serum agglutination test ▶️ fourfold increase in titer

Antibodies against brucella ▶️ >1:160 to be (+)

Question 10

Primary source of transmission of campylobacter jejuni, and serotype associated with is major complication and what is it?

Answer 10

Fecal-oral poultry

Guillain-Barré syndrome ▶️ serotype O:19

Question 11

Toxins of vibrio cholerae. What do you use to diagnose?

Answer 11

Cholerae toxin ▶️ ADP ribosylation Gs alpha ▶️ (+) adenylate cyclase ▶️ ⬆️ cAMP ▶️ efflux Cl, H2O
Motility, mucinase, toxin coregulated pili (TCP)
Dx: culture stool on TBCS, Oxidase (+)

Question 12

Diagnose of Gastroenteritis by ETEC. Pathogenesis.

Answer 12

Identify LT (Heat labile toxin) ▶️ immunoassay, bioassay, DNA probe

• LT ▶️ ADP ribosylation of Gs ▶️ (+) adenylate cyclase
• ST ▶️ (+) guanylate cyclase

Question 13

Type of E. Coli that causes inflammatory diarrhea. Closely related with which microorganism?

Answer 13

E. Coli Enteroinvasive (EIEC) ▶️ unique of all types to cause inflammatory diarrhea
Closely related with shigella

Question 14

Pathogenic mechanism and diagnose of EHEC gastroenteritis. What is particular in its clinical presentation?

Answer 14

Verotoxin ▶️ shigella-like toxins 1 and 2 ▶️ block 60S subunit ▶️ ⬇️ protein synthesis.
Dx: no fermentation of sorbitol
bloody diarrhea but NO INVASIVE

Question 15

How do you focus the treatment of EHEC gastroenteritis?

Answer 15

Avoid antibiotics ▶️ ⬆️ risk of HUS

Question 16

What medium do you culture klebsiella pneumoniae, how do you identify? Why does it have that presentation?

Answer 16

McConkey agar

Pink colonies ▶️ lactose fermentation

Question 17

How do expect the culture report of a shigellosis?

Answer 17

Gram (-) bacilli, lactose fermenter (-) [colorless in McConkey of EMB], produce H2S (-), nonmotile

Question 18

Important toxins of shigella. Most severe strain.

Answer 18

M cells invasion ▶️ shallow ulcers
Endotoxin
Shiga toxin ▶️ clipping 60S subunit ▶️ (-) protein synthesis [produced by S. dysenteriae type 1 strain ▶️ most severe]

Question 19

Diagnosis of yersinia pestis infection

Answer 19

Serodiagnosis or Direct immunofluorescence

Question 20

Triad in clinical presentation of bubonic plague. How can you get bubonic and pneumonic plague?

Answer 20

• Bubonic plague: fever, regional buboes, conjunctivitis. Transmitted by flea bite.
• Pneumonic plague: highly contagious, human-human by respiratory droplets and biowarfare (aerosol)

Question 21

Why does proteus mirabilis induce formation of struvite stones? Diseases that can cause.

Answer 21

Urease (+)

UTI, septicemia

Question 22

Predisposing factors to salmonella infections

Answer 22

Decreased stomach acid

Impairment mononuclear cells (sickle cell disease)

Question 23

What is the use of the widal test?

Answer 23

Antibodies to O, Vi, and H Ag by agglutination ▶️ Dx salmonella subspecies other than typhi

Question 24

Complications of typhoid fever if untreated

Answer 24

Necrosis of Peter patches ▶️ perforation 
Thrombophlebitis 
Cholecystitis 
Pneumonia
Abscess

Question 25

What does haemophilus influenzae need to grow in a culture of blood agar? Most vulnerable group to get meningitis?

Answer 25

Factor X (hemin), V (NAD) ▶️ chocolate agar 
Unvaccinated children 3 mo to 2 years (also pneumonia, epiglotitis)

Question 26

Disease caused by pasteurella multocida, how is it transmitted? Treatment.

Answer 26

Cellulitis + lymphadenitis
Cat bites
Amoxicillin/clavulanate

Question 27

Most common gran negative associated with sepsis

Answer 27

Nowadays E. coli

*previously bacteroides, decreased because prophylaxis

Question 28

Disease caused by bacteroides, and I which situations do you expect it causes them?

Answer 28

• sepsis, abdominal abscess, peritonitis

- bowel defect (cytotoxic drug for cancer), abdominal trauma or surgery

Question 29

Region where yersinia pestis is endemic in US?

Answer 29

Desert southwest

Question 30

What other bacteria besides EHEC can lead to hemolytic uremic syndrome? Why?

Answer 30

Shigella

Verotoxin of EHEC is a shigella like toxin

Question 31

What suggest an endoscopic finding of “red cherry” and x-ray “thumbprint sign” in a child? Etiology.

Answer 31

Epiglotitis

Haemophilus influenzae

Question 32

What contribute to produce chronic pneumonia by pseudomonas aeruginosa in cystic fibrosis patients?

Answer 32

Mucoid polysaccharide capsule ▶️ biofilm formation