Salmonella Typhi

Salmonella Typhi

Q. 1

An increased frequency of infections due to which of the following organism has been reported among patients with achlorhydria?

 A

Salmonella

 B

Shigella

 C

Entamoeba

 D

Vibrio cholera

Q. 1

An increased frequency of infections due to which of the following organism has been reported among patients with achlorhydria?

 A

Salmonella

 B

Shigella

 C

Entamoeba

 D

Vibrio cholera

Ans. A

Explanation:

The acidic pH of the stomach is an important barrier to some enteric pathogens. An increased frequency of infections due to Salmonella, G. lamblia, is seen in patients who have undergone gastric surgery or are achlorhydric for some other reason.


Reference:
Harrisons Principles of Internal Medicine, 18th Edition, Page1085


Q. 2

Salmonella typhi is the causative agent of typhoid fever. What is the infective dose of S. typhi?

 A

One bacillus

 B

10 8- 10 10 bacilli

 C

10 3-10 6 bacilli

 D

1-10 bacilli

Q. 2

Salmonella typhi is the causative agent of typhoid fever. What is the infective dose of S. typhi?

 A

One bacillus

 B

10 8- 10 10 bacilli

 C

10 3-10 6 bacilli

 D

1-10 bacilli

Ans. C

Explanation:

The infectious dose of Salmonella typhi causing typhoid fever is 10 3 – 10 6 colony forming units. Any conditions which decrease either the stomach acidity or intestinal integrity increases the susceptibility to Salmonella infection.

 
Salmonella typhi and S. paratyphi is known to cause enteric fever.
Salmonellae are gram-negative, non-spore-forming, facultatively anaerobic bacilli.
They produce acid on glucose fermentation, reduce nitrates, and do not produce cytochrome oxidase.
Salmonella infection begins with the ingestion of contaminated water.
They causes enteric fever which  is a systemic disease characterized by fever and abdominal pain. 
 
Ref: Harrison’s Principles of Internal Medicine, 18e chapter 153, By David A. Pegues; Samuel I. Miller.

Q. 3

All of the following organisms are known to survive intracellularly except –

 A

Neisseria meningitides

 B

Salmonella typhi.

 C

Streptococcus pyogenes

 D

Legionella pneumophila

Q. 3

All of the following organisms are known to survive intracellularly except –

 A

Neisseria meningitides

 B

Salmonella typhi.

 C

Streptococcus pyogenes

 D

Legionella pneumophila

Ans. C

Explanation:

Ans. is ‘c’ i.e., Streptococcus pyogenes

Facultative intracellular organisms

.  Besides obligate intracellular organisms, some other organisms can live intracellularly —> Facultative intracellular organisms.

.  These bacteria also have capability of synthesis their own ATP, So they usually live extracellularly (in contrast obligate intracellular organisms).

.  These bacteria are phagocytosed by the host’s macrophages and neutrophils yet survived within these WBCs by inhibiting phagosome – lysosome fusion, thus escaping host’s toxic H2O2 and superoxide radicals.

. Important examples :‑

Listeria monocytogenes          – Yersinia                               – Brucella               – Mycobacterium

– Neisseria                             – Salmonella typhi                  – Legionella            – Francisella tularensis


Q. 4

Selenite F broth is an enrichment media for ‑

 A

Salmonella

 B

Shigella

 C

E. coil

 D

a and b

Q. 4

Selenite F broth is an enrichment media for ‑

 A

Salmonella

 B

Shigella

 C

E. coil

 D

a and b

Ans. D

Explanation:

Ans. is ‘a’ i.e., Salmonella; ‘b’ i.e., Shigella


Q. 5

The following are gas producing salmonella except-

 A

S. typhi

 B

S. enteritidis

 C

S. cholera

 D

S. typhimurium

Q. 5

The following are gas producing salmonella except-

 A

S. typhi

 B

S. enteritidis

 C

S. cholera

 D

S. typhimurium

Ans. A

Explanation:

Ans. is ‘a’ i.e., S. typhi 

Salmonella

.    Salmonellae are

–  Gram negative bacilli

–  Motile with peritrichate flagella except for one type S. gallinarum-pullorum which is always non motile.

.  Salmonellae ferment glucose, mannitol and maltose, forming acid and gas. An important exception is S.typhi which does not form gas.

S. typhi need tryptophan as the growth factor.

.  S. typhi produces H2S but S paratyphi A does not.


Q. 6

Salmonella typhi is the causative agent of typhoid fever. The infective does of S.typhi 

 A

One bacillus

 B

108-1010 bacilli

 C

102-105 bacilli

 D

1-10 bacilli

Q. 6

Salmonella typhi is the causative agent of typhoid fever. The infective does of S.typhi 

 A

One bacillus

 B

108-1010 bacilli

 C

102-105 bacilli

 D

1-10 bacilli

Ans. C

Explanation:

Ans. is ‘c’ i.e., 102-105 bacilli 

In human volunteer experiments, the infective dose was found to be 103-106 bacilli.

Organism                                                  Infective dose

. ETEC . EIEC . EHEC

.  Shigella

.  Campylobactor jejuni

. Yersinia enterocolitica

. Vibrio

 

106-101°

108-10m

10-100(

104

108-109

1010 (if source of infection is water) 102-104 (if source of infection is food)


Q. 7

Incubation period of salmonella typhi –

 A

2-5 days

 B

3-21 days

 C

14-25 days

 D

0-60 days

Q. 7

Incubation period of salmonella typhi –

 A

2-5 days

 B

3-21 days

 C

14-25 days

 D

0-60 days

Ans. B

Explanation:

Ans. is ‘b’ i.e., 3-21 days 

Enteric fever

.   The term enteric fever includes typhoid fever caused by S.typhi and paratyphoid fever caused by S. paratyphi A, B and C.

.  The ability to resist intracellular killing and to multiply with in these cells is a measure of virulence of salmonella.

.  The incubation period for S. typhi ranges from 3 to 21 days.

.  Most prominant symptom of this systemic infection is prolonged fever. (Step-ladder pyrexia).

.  Early physical findings are —> Rash (rose spot), Relative bradycardia, Hepatosplenomegaly, Epistaxis.

Complications occur in 3′ and41  weeks –> Intestinal perforation and GI hemorrhage are the two most common complications. 


Q. 8

Which of the following is true regarding Salmonella infection –

 A

Urine culture is + ve in 1″ week

 B

Stool culture is + ve in 1″ week

 C

Blood culture is + ve in 3-7 days

 D

Widal test is +ve in 1″ week

Q. 8

Which of the following is true regarding Salmonella infection –

 A

Urine culture is + ve in 1″ week

 B

Stool culture is + ve in 1″ week

 C

Blood culture is + ve in 3-7 days

 D

Widal test is +ve in 1″ week

Ans. C

Explanation:

Blood culture is + ve in 3-7 days


Q. 9

Vi antigen found in –

 A

Salmonella paratyphi ‘C’

 B

Salmonella Typhi

 C

Salmonella dublin

 D

All

Q. 9

Vi antigen found in –

 A

Salmonella paratyphi ‘C’

 B

Salmonella Typhi

 C

Salmonella dublin

 D

All

Ans. D

Explanation:

Ans :D.)All

The Vi antigen, is a capsular polysaccharide found mainly in Salmonella typhi and S. paratyphi C, as well as in a few strains of S. dublin and Citrobacter freundii


Q. 10

Microorganisms that enter freshly laid eggs are

 A

Salmonella

 B

Brucella

 C

Shigella

 D

Vibrio cholerae

Q. 10

Microorganisms that enter freshly laid eggs are

 A

Salmonella

 B

Brucella

 C

Shigella

 D

Vibrio cholerae

Ans. A

Explanation:

Ans. is ‘a’ i.e., Salmonella 

.      Salmonella can enter through the shell if eggs are left on contaminated chicken feed or feces and grow inside.


Q. 11

Growth factor needed for salmonella – 

 A

Tryptophan

 B

Niacin

 C

B-12

 D

Citrate

Q. 11

Growth factor needed for salmonella – 

 A

Tryptophan

 B

Niacin

 C

B-12

 D

Citrate

Ans. A

Explanation:

Ans. is ‘a’ i.e., Tryptophan 


Q. 12

Which of the following organism requires tryptophan for growth –

 A

H. influenza

 B

Vibrio

 C

Gonococci

 D

Salmonella typhi

Q. 12

Which of the following organism requires tryptophan for growth –

 A

H. influenza

 B

Vibrio

 C

Gonococci

 D

Salmonella typhi

Ans. D

Explanation:

Ans. is ‘d’ i.e., Salmonella typhi 


Q. 13

Which of the following does not have non-human reservoir –

 A

Salmonella typhi

 B

N. Gonorrhoea

 C

E. coli

 D

a and b

Q. 13

Which of the following does not have non-human reservoir –

 A

Salmonella typhi

 B

N. Gonorrhoea

 C

E. coli

 D

a and b

Ans. D

Explanation:

Ans. is ‘a’ i.e., Salmonella typhi; ‘b’ i.e., N. Gonorrhoea

  • Reservoir of infection may be :‑

1)       Human reservoir

2)       Non – Human reservoir

i)         Animal or bird

ii)       Non – living things (e.g. – soil)

  • Most important reservoir or source of infection for human is man itself. However, most of the infections have non­human reservoir also.
  • There are some infections, which have only human reservoir, i.e. they do not have non-human reservoir. Such infections are Measles, Typhoid (S. typhi), Syphilis (T. pallidum), Gonorrhoea (gonococci), Loose borne relapsing fever (Borrelia recurrents), cholera (V cholerae).

Q. 14

Which of the following is least likely to cause infective endocarditis :

 A

Staphylococcus albus

 B

Streptococcus faecalis

 C

Salmonella typhi

 D

Pseudomonas aeruginosa

Q. 14

Which of the following is least likely to cause infective endocarditis :

 A

Staphylococcus albus

 B

Streptococcus faecalis

 C

Salmonella typhi

 D

Pseudomonas aeruginosa

Ans. C

Explanation:

Answer is C (Salmonella Typhi)

Endocarditis is common with staphylococcus albus,.streptococcus fecalis and pseadontonas aeruginosa. Endocarditis has only been mentioned as rare complication of salmonella typhi infection. —

The least likely organism to infective endocarditis amongst the options provided is salmonella typhi. Other options

 

Staphylococcus albus (Staph. epidermis) (Coagulase Negative staph.)

 treptococcus fecalis (Enterococci)

Pseudomonas Aeroginosa Gram negative bacilli

•   S. epidermis (albus) is the most

•   Streptococci fecalis is the most

•  Common agent in endocarditis among

Common coagulase negative

common cause of enterococcal

infection drug users

staphylococii

infective endocarditis

•   P. aerug inosa infects the native heart

•   Coagulase negative staph (S.

•   These organism account for 10 – 20%

valves of intravenous drug users as

epidermidis/alba) are the most common cause of ‘Prosthetic  valve endocarditis’

of cases of bacterial endocarditis

well as prosthetic heart valves


Q. 15

Which of the following is non-lactose fermenting bacteria ‑

 A

E. coli

 B

Klebsiellla

 C

Citrobacter

 D

Salmonella

Q. 15

Which of the following is non-lactose fermenting bacteria ‑

 A

E. coli

 B

Klebsiellla

 C

Citrobacter

 D

Salmonella

Ans. D

Explanation:

Ans. is ‘d’ i.e., Salmonella

Lactose fermentation by Enterobacteriacae members

Initially Enterobacteriacea was classifed on the bases of their lactose fermenting ability on MacConkey’s medium, the most popular medium for the isolation of fecal bacilli.

Lactose fermenters produce pink/bright red colonies on MacConkey’s agar , while lactose non-fermenters produce pale colonies :

i) Lactose fermenters (rapid) : These are Coliforms, e.g. Escherichia, Klebsiella and Enterobacter aerogenes.

ii) Late lactose fermenters (slow) : These are Shigella Sonnei, Serratia, Citrobacter, Arizona, Providencia and Ervinia.

iii) Non-lactose fermenters : Shigella except Shigella Sonnei, Salmonella, Proteus.


Q. 16

DCA media used in differentiation of which infection‑

 A

Salmonella

 B

Staph aureus

 C

H. influenzae

 D

Bordetella

Q. 16

DCA media used in differentiation of which infection‑

 A

Salmonella

 B

Staph aureus

 C

H. influenzae

 D

Bordetella

Ans. A

Explanation:

Ans. is ‘a’ i.e., Salmonella

Deoxycholate citrate agar (DCA) medium is a selective medium for Salmonella and Shigella.

It is also used as a differential medium to differentiate lactose fermenter from non-lactose fermenting enteric pathogens. Salmonella and Shigella (except Shigella Sonnei) are non-lactose fermenters.


Q. 17

Salmonella infection is most commonly caused by‑

 A

Infected water

 B

Infected vegetable

 C

Aerosol infection

 D

a and b both

Q. 17

Salmonella infection is most commonly caused by‑

 A

Infected water

 B

Infected vegetable

 C

Aerosol infection

 D

a and b both

Ans. D

Explanation:

Ans. is ‘a & b’ i.e., Infected water & Infected vegetable

Transmission of salmonella tvphi

Typhoid fever is transmitted via the faecal-oral route or urine-oral routes. This may take place directly through soiled hands contaminated with faeces or urine of cases or carriers, or indirectly by the ingestion of contaminated water, milk and/or food, or through files.


Q. 18

Infective dose of salmonella typhi ‑

 A

10 bacilli

 B

1000 bacilli

 C

103-106 bacilli

 D

1010 – 1012 bacilli

Q. 18

Infective dose of salmonella typhi ‑

 A

10 bacilli

 B

1000 bacilli

 C

103-106 bacilli

 D

1010 – 1012 bacilli

Ans. C

Explanation:

Ans. is ‘c’ i.e., 103-106 bacilli

In human volunteer experiments, the infective dose was found to be 103-106 bacilli.



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