A microbiologist is reading plates from a cerebrospinal fluid (CSF) culture.She notices that there is growth on chocolate agar (CHOC), but no growth on sheep blood agar (SBA) or MacConkey (MAC) agar.The Gram stain showed a gram-negative bacillus.What organism should be suspected?
A)Streptococcus pneumoniae
B)Staphylococcus aureus
C)Haemophilus influenzae
D)Escherichia coli

Question

Quizplus · Accepted Answer

H.influenzae is a tiny, gram-negative rod that is very fastidious.It will not grow on MAC and will not grow on SBA.It will grow on CHOC because additional nutritional growth requirements are added to the media.Streptococcus pneumoniae and Staphylococcus aureus are gram-positive cocci that grow well on BAP but do not grow on MAC.E.coli is a gram-negative rod that grows well on SBA, CHOC, and MAC.

A Microbiologist Is Reading Plates from a Cerebrospinal Fluid (CSF)