Page 1 of 1: Microbiology:C.diptheriae like organisms

cingulate_gyrus2006 · Credits: 22760 My Scrapbook

this is an AIIMS nov 2004 ques.
In a completely immunized child against Diptheria, the throat swab was collected, It showed the presence of coranebacterium diptheriae like organisms on Albert staining. These organisms can have one of the following properties on further laboratory processing-
a) It can grow in potassium tellurate medium.
b) It would show a positive Eleck’s precipitation test.
c) It can be pathogenic to experimental guinea pigs.
d) It can produce cytotoxicity in tissue cultures.

drsmita_s · Credits: 18609 My Scrapbook

i read the answer from amit aashish. the answer is probably right but i'm not convinced with the explaination given, so i searched extensively on the net and this is my opinion:
guide says that this child is a carrier of diphtheria, but i disagree with them, i feel that this question is talking about diphtheroids ( ques clearly says C.diphtheriae like organisms) which are normal commensals in our throat. but these will not produce toxins responsible for pathogenecity. if the organism was C.diphtheriae, it would produce toxins and hence will show positive tests for toxin ,but ofcourse , will not produce disease in the child since the child will have antitoxins present after vaccination.

now what i got from net search is that diphtheroids can grow in potassium tellurite agar but the colonies will be dark brown without halos, whereas with C.diphtheriae colonies will be black in colour with halos.
this means option a ) is correct and is the answer . the rest three options are virulence tests for toxin presence which will be given by C.diphtheriae and not by diphtheroids.
more opinions are welcome.

spaw12345 · Credits: 3814 My Scrapbook

i agree with drsmita

aap · Credits: 2289 My Scrapbook

yes the answer is a bec if it were C.dip it wud have to be proved to be pathogenic by the remaining three options so as to cause a disease. besides it clearly says the chid was immunised for dip

cingulate_gyrus2006 · Credits: 22760 My Scrapbook

In both ways answer is correct.

It can be C. Ditheria It can be diptheroids.
Explanation in Amith seems to be logic .
Immunization against diphtheria wont eradicate the carriers.

drsmita_s · Credits: 18609 My Scrapbook

well, i believe that diphtheroids can only cause option a) , cannot cause option b, c, d.
amit aashish is correct in saying that Immunization against diphtheria wont eradicate the carrier state , but when such a C.diphtheriae organism is cultured from throat swab, it will cause option a, b, c, as well as d, since it produces toxins. diphtheroids do not produce toxins.

kk05 · Credits: 240 My Scrapbook

option ais correct

vivek_patel · Credits: 2230 My Scrapbook

In a completely immunized child against Diptheria, the throat swab was collected, It showed the presence of coranebacterium diptheriae like organisms on Albert staining. These organisms can have one of the following properties on further laboratory processing-
a) It can grow in potassium tellurate medium.
b) It would show a positive Eleck’s precipitation test.
c) It can be pathogenic to experimental guinea pigs.
d) It can produce cytotoxicity in tissue cultures.
ans....A

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