Question

Case Study #1

Clinical history: An HIV positive male presented in clinic with confusion and disorientation. He had a fever 38.5°C and photophobia. His CD4 T cell count was 80/ul. An MRI and lumbar puncture were performed. The MRI showed various small lesions within the brain. CSF analysis indicated 32 White Blood Cells/ul with 89% lymphocytes, and 6% monocytes, glucose of 22mg/dl, and protein of 89mg/dl. Gram stain showed yeast and India ink negative stain showed a thick capsule.

Image Gallery:  

India Ink stain of CSF

MRI of patient's brain - arrows indicate lesions Alcian Blue stain of CSF

Which of the following is the most likely pathogen?

1. Cryptococcus neoformans
2. Aspergillus fumigatus
3. Candida albicans
4. Histoplasma capsulatum
5. Pneumocystis jiroveci

What would be the appropriate therapy?

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Case Study #2

Clinical history: A 33-year-old female dairy farmer develops a severe headache unrelieved by medication and neck stiffness. On physical examination, her temperature is 38.2°C. She has no papilledema. (Papilledema is a condition in which increased pressure in or around the brain causes the part of the optic nerve inside the eye to swell. Symptoms may be fleeting disturbances in vision, headache, vomiting, or a combination of these.) A lumbar puncture is performed, and a Gram stain of the CSF obtained shows many short, gram-positive rods and also a proliferation of segmented neutrophils.

Read the clinical history CAREFULLY. That is all the information you need to suggest a diagnosis. Of course, a complete diagnosis will depend on laboratory findings after culture and sensitivity. But, just based on the information here, the patient can be started on a regimen of treatment.  

What would be that regimen of treatment?

Venture a guess as to the name of this organism.  

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Case Study #3

Clinical History: A 67-year-old male had rheumatic heart disease for thirty years. Three months prior to death he began to have episodes of fever and chills accompanied by signs of worsening congestive heart failure. Splinter hemorrhages and purpuric skin rashes were noted three weeks before death.

Laboratory Findings: Blood cultures grew alpha-hemolytic streptococci. Gram stain shows gram positive cocci in chains. Autopsy revealed thickening of the mitral valve. Many friable calcified pink-gray granular lesions were present on the valve.

   Growth on blood agar Splinter hemorrages

Most cases that present with these findings are caused by?

1. Chlamydiae
2. Rickettsiae
3. Fungi
4. Bacteria
5. Viruses

In this particular patient the MOST LIKELY causative organism was?

1. Group A Streptococci
2. Viridans Streptococci
3. Streptococcus pyogenes
4. Group B Streptococci

The heart valve MOST OFTEN affected by infective endocarditis in IV drug abusers is the:

1. Aortic valve
2. Mitral valve
3. Pulmonary valve
4. Tricuspid valve

Be careful with your answer!

Which of these organisms are normal flora of the throat and are associated with dental caries, brain abscesses, and the case study presented here?

1. Streptococcus pyogenes
2. Streptococcus viridans
3. Streptococcus pneumoniae
4. Peptostreptococcus species

A throat culture grows normal oropharyngeal microbiota. The coagulase test for the organism is positive. What is the genus and species of the organism?

A. Staphylococcus aureus
B. Streptococcus agalactiae
C. Streptococcus pyogenes
D. Staphylococcus epidermidis

Answer 1

1)The clinical features of meningitis , the gram stain showing yeast form, India ink staining showing the presence of capsules indicate cryptococcus neoformans.

2)A dairy farmer develops features of meningitis. The gram stain of CSF shows gram positive rods .

So it is probably due to listeria monocytogenes.

The treatment regimen will be ampicillin and gentamicin.

3)The presenceof gram positive cocci in chains indicate streptococcus. The symptoms and signs along with green colored alpha hemolytic colonies point to the streptococcus viridans. (A bacteria)

Most cases are caused by bacteria.

The most likely causative organism is viridans streptococcus.

The most commonly affected valve in endocarditis in IV drug abusers is the tricuspid valve.

Streptococcus viridans are Normal flora and cause dental caries.

Coagulase positive normal oropharyngeal microorganism is Staphylococcus aureus.