FERMENTATIVE GRAM-NEGATIVE (-) BACILLI (ENTEROBACTERIACEAE)

Question 2

General characteristics of Enterobacteriaceae:

Answer 2

1. Gram-negative rods; either motile with peritrichous flagella or non-motile (“SKY”)
2. Facultative anaerobes that grow well on artificial media
3. Catalase positive, oxidase negative, reduce nitrate to nitrite
4. Fermenters (produce acid in presence or absence of oxygen); All are glucose fermenters with or without gas production

Question 3

Antigens of Enterobacteriaceae:

Answer 3

• O antigen
• H antigen
• K antigen

Question 4

O antigen other name:

Answer 4

Somatic antigen

Question 5

H antigen other name:

Answer 5

Flagellar antigen

Question 6

K antigen other name:

Answer 6

Capsular antigen

Question 7

location of O antigen

Answer 7

Cell wall

Question 8

location of H antigen:

Answer 8

Flagella

Question 9

location of K antigen:

Answer 9

Capsule

Question 10

Enterobacteriaceae antigen used for serological grouping of Salmonella & Shigella

Answer 10

O antigen

Question 11

Enterobacteriaceae antigen used to serotype Salmonella

Answer 11

H antigen

Question 12

Enterobacteriaceae antigen role in preventing phagocytosis

Answer 12

K antigen

Question 13

Predominant aerobe in the GIT; colonic normal flora (nonpathogenic strains) of human and animals

Answer 13

Escherichia coli (Colon bacillus)

Question 14

Diseases caused by E. coli:

Answer 14

• Diarrhea
• UTI (most common cause)
• Neonatal meningitis
• Gram (-) sepsis

Mnemonic: DUNG

Question 15

Also known as Shiga toxin-producing (STEC) or verotoxin-producing (VTEC); Diarrhea, hemorrhagic colitis, hemolytic uremic syndrome (HUS)

Answer 15

Enterohemorrhagic (EHEC)

Question 16

Transmission of EHEC:

Answer 16

Undercooked, raw milk, apple cider

Question 17

Most common isolate of group & pathogen most often isolated from bloody stools:

Answer 17

E. coli O157:H7

Question 18

Culture media for E. coli O157:H7

Answer 18

Sorbitol-MacConkey Agar

Note: E. coli O157:H7 does not ferment sorbitol; colonies are colorless

Question 19

Causes “Traveler’s diarrhea” (aka Montezuma’s revenge Turista), diarrhea in infants

Answer 19

Enterotoxigenic (ETEC)

Question 20

Transmission of ETEC:

Answer 20

Contaminated food or water

Question 21

Diarrhea in infants (Pediatric diarrhea); major pathogen in infants in developing countries

Answer 21

Enteropathogenic (EPEC)

Question 22

Transmission of EPEC:

Answer 22

Formula & food contaminated with fecal material

Question 23

Diarrhea in developing countries; chronic diarrhea in HIV-infected patients

Answer 23

Enteroaggregative (EAEC)

Question 24

Diarrhea & UTI; Most common in children in developing countries:

Answer 24

Diffusely adherent (DAEC)

Question 25

Common ventilator-associated pneumonia and is also associated with alcoholism (pneumococcus is still more common) and aspiration

Answer 25

KLebsiella pneumoniae

Question 26

"Currant jelly" sputum is described in the infection of __________.

Answer 26

K. pneumonaie

Question 27

The only indole positive Klebsiella; IMVIC: +-++

Answer 27

Klebsiella oxytoca

Question 28

two (2) general types of Salmonella:

Answer 28

1. Salmonella typhi 2. Non-typhoid strains

Question 29

Bacteria that causes typhoid fever:

Answer 29

Salmonella typhi

Question 30

Non-typhoid strains:

Answer 30

S. enterica S. enteritidis

Question 31

Diseases caused by Salmonella:

Answer 31

- Endotoxin - Entercolitis - Septicemic (estraintestinal) disease - Enteric fever (typhoid)

Question 32

Salmonella stain that causes less severe typhoid fever:

Answer 32

Salmonella paratyphi

Question 33

Salmonella strain that causes serious and recurring problems for patients with sickle cell disease

Answer 33

Salmonella osteomylitis

Question 34

Signs and symptoms of typhoid fever:

Answer 34

- Abdominal pain - Fever - "Rose spots" may appear on the trunk of the patient in the second and third weeks - Pulse-temperature dissociation (high fever with slow pulse)

Question 35

Diagnosis for typhoid fever:

Answer 35

Culture (stool, blood) (Gold standard)

Question 36

Most communicable of bacterial diarrhea (<200 bacilli needed to infect a person)

Answer 36

Shigella

Question 37

Shigella strain that causes the most severe disease:

Answer 37

Shigella dysenteriae

Question 38

Only Shigella strain that is ONPG (late lactose fermenter) positive:

Answer 38

Shigella sonnie

Question 39

Only Shigella strain that is Catalase test, ONPG, Mannitol test negative

Answer 39

Shigella dysenteriae

Question 40

Shigella strains that is positive for Catalase test and Mannitol test and negative for ONPG:

Answer 40

Shigella flexneri Shigella boydii

Question 41

Bacteria that produces swarming on agar

Answer 41

Proteus

Question 42

Most common proteus strain that is indole (-)

Answer 42

Proteus mirabilis

Question 43

Differentiate P. mirabilis and P. vulgaris:

Answer 43

P. mirabilis - Indole (-) - TSI = K/A P. vulgaris - Indole (+) - TSI = A/A

Question 44

Diseases caused by Proteus:

Answer 44

- UTI - Wound infections - Septicemia

Question 45

Kidney stone associated with Proteus:

Answer 45

- Struvite kidney stones (then to urinary obstruction); (Proetus produces a powerful urease that hydrolyzes urea to ammonia and CO2, leading to struvite kidney stone [alkaline])

Question 46

Slow lactose fermenters, not dominant pathogen for any clinical condition; often resistant to many antibiotics

Answer 46

Citrobacter and Serratia marcescens

Question 47

Classified as BSL I; produce distinctive red colonies (red pigment); catalase (+), DNase (+)

Answer 47

Serratia marcescens

Question 48

Bacteria that mimics Crohn's disease or appendicitis; can cause inflammation around appendix or in mesenteric lymph nodes (mesenteric adenitis)

Answer 48

Yersinia enterocolitica

Question 49

Cause of bubonic plague ('"black death");

Answer 49

Yersinia pestis

Question 50

Humans get disease from what rat flea?

Answer 50

Xenopsylla cheopsis

Question 51

Signs and symptoms of bubonic plague:

Answer 51

Fever, chills, headache; intense pain/swelling of a lymph node area (bubo)

Question 52

Chief reservoir are reptiles & freshwater fish; Infections often involve aquatic environments; Opportunistic; H2S (+); Indole (+) differentiates from Salmonella:

Answer 52

Edwardsiella tarda

Question 53

Only oxidase (+) Enterobacteriaceae; pleomorphic gram-negative rods in singles, pairs, short chains, or long filaments' Biochemical & antigenic similarities to Shigella; Motile

Answer 53

Plesiomonas shigelloides (now included in Enterobacteriaceae)