Gram Negative Rods 2

Question 1

State the antigenic structure of salmonella ?

Answer 1

O antigen somatic o
H antigen flagellar
Vi antigen virulance capsular like

Question 2

Serotype of salmonella paratyphi ?

Answer 2

Group A,B,C based on o antigen

Question 3

Serotype of salmonella typhi ?

Answer 3

Group D

Question 4

State the test of indole and ureas for salmonella ?

Answer 4

Negative

Question 5

Triple sugar iron test TSI slant for salmonella typhi ?

Answer 5

Partial fermentation with H2s production

Question 6

Intra cellular persistence in macrophage ?

Answer 6

Salmonella typhi by the presence of Vi antigen capsule

Question 7

Feco-oral route after ingestion of contaminated food or drinks e.g. raw vegetables, fruits, raw shell fish and milk products. The primary site of infection is the small intestine

Answer 7

Enteric fever typhoid

Question 8

Clinical manifestations of typhoid enteric fever start with ?
fever, headache, malaise,
tender abdomen, constipation.

Answer 8

Secondry bacterimia

Question 9

Incubation period of salmonella typhi ?

Answer 9

1-2 weeks

Question 10

tube agglutination test designed to
detect anti-salmonella antibodies titre in the
patient’s serum.

Answer 10

Widal test

Question 11

Serologic diagnosis of enteric fever typhiod can be done with

Answer 11

Elisa , widal and immunoblot assay

Question 12

intestinal Infection(enteritis) with no blood invasion caused
by

Answer 12

Salmonella typhimurium and Salmonella enteritidis.

Question 13

Blood culture and serological tests is of no value (no blood invasion). In which case ?

Answer 13

Salmonella food poisoning

Question 14

Gram negative bacilli, non-motile, non-capsulated. Causing bacillary
dysentery(bloody diarrhea).

Answer 14

Shigella

Question 15

It is heat labile.
The toxin has enterotoxic, cytotoxic and neurotoxic effects:
o causes watery diarrhea.
o causes necrosis and ulceration of mucosa with formation of a
pseudomembrane.
o It is similar to EHEC E. coli verotoxin .

Answer 15

Shiga toxin (Shigella dysenteriae type I)

Question 16

acid resistance which allows it to survive passage through the stomach to reach the intestine.

Answer 16

Bacillary dysentery shiglosis

Question 17

The organisms grow on simple and enriched media, and may
produce concentric wavy “swarming” growth, due to their
high motility.

Answer 17

Proteus

Question 18

Urease hydrolyzes the urea in urine to form ammonia, which raises the pH,
producing an alkaline urine.
Cause urinary tract infection

Answer 18

Proteus

Question 19

Your patient is a 6-year-old boy with bloody diarrhea for the past 2 days accompanied by fever to 40°C and vomiting. He has a pet corn snake. Blood culture and stool culture from the boy and stool culture from the snake (taken very carefully!) revealed the same organism. The cultures grew a gram-negative rod that formed colorless colonies on EMB agar. Which one of the following bacteria is the most likely cause of this infection?
(A) Helicobacter pylori
(B) Proteus mirabilis
(C) Salmonella enterica
(D) Shigella dysenteriae
(E) Vibrio cholerae

Answer 19

Salmonella enterica

Question 20

Your patient is a 25-year-old woman with pain on urination and cloudy urine but no fever or flank pain. She has not been hospi-talized. You think she probably has cystitis, an infection of the urinary bladder. A Gram stain of the urine reveals gram-negative rods. Culture of the urine on EMB agar shows colorless colonies, and a urease test was positive. Swarming motility was noted on the blood agar plate. Which one of the following bacteria is the most likely cause of this infection?

(A) Escherichia coli

(B) Helicobacter pylori

(C) Proteus mirabilis

(D) Pseudomonas aeruginosa

Answer 20

Proteus mirabilis

Question 21

Medical physicians, working in a refugee camp in central Africa, are concerned with the number of young children presenting with high fever, bloody diarrhea, and dehydration. The crowded living conditions of the camp suggest person-to-person contact. laboratory studies are available. The suspected organism is nonmotile, Gram-negative bacilli
What is the causative organism

Answer 21

Shigellae

Question 22

Medical physicians, working in a refugee camp in central Africa, are concerned with the number of young children presenting with high fever, bloody diarrhea, and dehydration. The crowded living conditions of the camp suggest person-to-person contact. laboratory studies are available. The suspected organism is nonmotile, Gram-negative bacilli

1- Describe the appearance of the microbial colonies on macConkeys medium.

Answer 22

Shigellea , pale yellow on maconcky agar

Question 23

78-year-old hospitalized male with an indwelling catheter develops a new onset of fever. The urine sample has an alkaline pH. The bacterium isolated from the urine is a urease-producing, highly motile, Gram- negative bacillus. Giving the following appearance on MaCconkeys medium
1-Write the name of the organism

Answer 23

Proteus

Question 24

78-year-old hospitalized male with an indwelling catheter develops a new onset of fever. The urine sample has an alkaline pH. The bacterium isolated from the urine is a urease-producing, highly motile, Gram- negative bacillus. Giving the following appearance on MaCconkeys medium

2-Is this organism lactose fermenter or non lactose fermenter

Answer 24

Non lactose