WBR0053

Author	PageAuthor::William J Gibson
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Microbiology, MainCategory::Pathology
Sub Category	SubCategory::General Principles, SubCategory::Infectious Disease
Prompt	Prompt::A microbiologist has been given a number of unknown clinical samples and is attempting to visualize organisms by gram stain. Which of the following organisms will he be unable to visualize with this method?
Answer A	AnswerA::Strep Pyogenes
Answer A Explanation	AnswerAExp::Incorrect - Strep Pyogenes is a gram positive coccus.
Answer B	AnswerB::H. Influenza
Answer B Explanation	AnswerBExp::Incorrect - H. Influenza is a gram negative rod.
Answer C	AnswerC::Bacteriodes Fragilis
Answer C Explanation	AnswerCExp::Incorrect - Bacteriodes Fragilis is a gram negative rod.
Answer D	AnswerD::Legionella Pneumophila
Answer D Explanation	AnswerDExp::Correct - See Explanation
Answer E	AnswerE::Corynebacterium Diptheria
Answer E Explanation	AnswerEExp::Incorrect - Corynebacterium Diptheria is a gram positive rod.
Right Answer	RightAnswer::D
Explanation	[[Explanation::Legionella Pneumophila is a primarily intracellular organism which gram stains poorly. The stain of choice for Legionella is a silver stain. Legionella infections cause atypical pneumonia and are associated with aerosols from contaminated water, such as certain air conditioning systems. The treatment of choice is a macrolide (eg erythromycin). Educational Objective: Legionella Pneumophila is a primarily intracellular organism which gram stains poorly. The stain of choice for Legionella is a silver stain. References :First Aid 2012 page 162 Tags :#Microbiology #Biochemistry Educational Objective: References: ]]
Approved	Approved::Yes
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