Question

1. What are positive tests for mycobacterium smegmatis and negative tests for mycobacterium smegmatis?

2. Provide a flow chart dichotomous key for the determination of mycobacteria smegmatis. Use the above tests provided to question 1.

3.Make a second dichotomous key using the following and in the following order for determining M.Smegmatis

-2 staining techniques

-morphology

-Aerotolerance

- 1 of the following ( Mannitol Salt Agar, MacConkey agar, Eosin methylene blue)

-2 tests of the following (Catalase test,Oxidase test, Nitrate reduction test, Citrate test, Decarboxylation test, Glucose Oxidation-Fermentation test, Phenol Red broth, Methyl red & voges proskauer test

-3 test of the following (Phenylalanine Deaminase test, starch hydrolysis (amylase test), DNA hydrolysis (Dnase test), Lipid hydrolysis, Casein hydrolysis, Gelatin hydrolysis, Urea hydrolysis, Bile esculin test, SIM test.

-Antibiotic succeptibility

Answer 1

1. positive tests are

Gram- stain positive, acid fast staining test positive, fermentation test:(glucose and catalase,) positive,

negative tests are

motility test negative at 25 degree celcius, lactose test negative, gelatinase test negative,phenylalanone aminotransferase test negative, citrate test negative, horse blood haemolysis test negative.

2. Gram Staining(+)--> acid fastening test (+) --> motility test (-) --> citrate test (-)-->fermentation test( Glucose (+)And Lactose (-)) --> Enzyme test( Catalase Test (+), Gelatinase test(-) and phenylalanone aminotransferase test (-).

3. Gram Staining (+), Acid fast Stain (+)-->rough white(yellowish) irregular colonies --> Citrate and horse blood haemolysis test negative (aerobic)-->macConkey agar growth (in absence of crystal violet)--> Catalase Test (+)--> fermentation test( Glucose (+))--> Gelatine hydrolase test (-)--> Starch hydrolysis test (-)--> Urea hydrolysis (+)--> suseptible to ethambutol, streptomycin,chloramphenicol, norfloxacin, tetracyclin,