You are reading culture plates today and identifying pathogens that grow from patient samples.
Which two pieces of information are absolutely critical in determining which additional tests must be done to identify the pathogen?
a) Appearance on charcoal agar
b) Endospore Stain
c) Gram Stain
d) Oxygen sensitivity
A 10 year old has a wound on the arm that the physician suspects is infected.
Upon culture, you see small white colonies growing on blood agar as well as chocolate agar.
You gram stain the colonies to find that they are gram positive cocci.
Which test will you perform first?
c) lactose fermentation
You have isolated catalase positive gram positive cocci from a wound culture.
Which test will you perform next?
b) P disc, containing optichin
c) A disc, containing bacitracin
You are working on a sputum culture.
You see mucoid alpha hemolytic colonies that number many more than the normal flora present.
The gram stain of the colonies shows gram positive cocci that are in lancet shaped pairs.
Which test will you do?
a) P disc, containing optichin
b) A disc, containing bacitracin
d) acid fast staining
You are working up a throat culture.
Standard procedure in plating throat cultures in your lab includes dropping an A disc near the initial inoculum in the first quandrant when streaking the specimen.
You examine the blood agar plate and see moderate normal flora and many beta hemolytic colonies that do not grow up to the A disc.
The beta hemolytic colonies are catalase negative gram positive cocci.
Which pathogen is in this throat culture?
b) Staphylococcus aureus
c) Streptococcus pyogenes
d) Staphylococcus epidermidis
You are working up a male genital culture.
You see no growth on the blood agar plate but small colonies growing on the chocolate agar plate. The gram stain shows gram negative cocci in pairs.
Which test will you do next?
You are working up a cerebrospinal fluid culture.
You find colonies growing on blood agar as well as chocolate agar.
The colonies are oxidase positive gram negative cocci.
The colonies ferment glucose and maltose but not sucrose or lactose.
You identify the pathogen as
a) Neisseria meningitidis
b) Haemophilus influenzae
c) Streptococcus pneumoniae
d) Neisseria gonorrhoeae
You are working up a urine culture.
You see >100 colonies that are gray and flat on the blood agar plate and >100 colonies that are bright pink on the MacConkey agar.
The IMViC results are Indole positive, Methyl Red positive, Vogues-Proskauer negative, Citrate negative.
You have identified the pathogen as
a) Citrobacter freundii
b) Escherichia coli
c) Enterobacter aerogenes
d) Proteus vulgaris
You are working up a stool culture.
On MacConkey agar you see many bright pink colonies and many clear colonies.
Which colonies are potential pathogens that require further testing?
a) Clear colonies, non lactose fermenters
b) Bright pink colonies, non lactose fermenters
c) Bright pink colonies, lactose fermenters
d) Clear colonies, lactose fermenters
DNA technology is useful in the identification of :
a) pathogens that are unable to be grown readily on artificial lab media.
b) pathogens that are no longer alive in the patient sample,
c) species that cannot be differentiated by conventional testing.
d) All of the above.