Micro

Question 1

Pneumonia causing agents:

1. gram negative, oxidase positive bacillus
2. Gram negative pleomorphic bacillus requiring factors X and V
3. Gram positive, catalase negative coccus
4. Gram positive, catalase positive coccus

Answer 1

1. gram negative, oxidase positive bacillus: psuedomonas aeruginosa - buzzwords: cystic fibrosis, blue green fruity smelling sputum
2. Gram negative pleomorphic bacillus requiring factors X and V: haemophilus influenza: pneumonia, pharyngitis, bronchitis, and otitis media
3. Gram positive, catalase negative coccus
   Streptococcus genus, especially S. pneumoniae - most common cause of typical pneumonia in adults. Sputum is rusty, tinged with brown blood
4. Gram positive, catalase positive coccus - staph aureus
   - aspiration pneumonia, salmon colored sputum

Question 2

Bright red, gelatinous sputum
alcoholic
pneumonia in alcoholic
Treatment?

Answer 2

Klebsiella pneumoniae

Gram negative, oxidase negative bacillus, lactose fermenting

Third generation cephalosporin with or without an aminoglycoside

Question 3

Several days after the flu, she develops high fever, dyspnea, productive cough and mental status changes. Cavitary lesion in her left lung.
Sputum is salmon colored

Answer 3

S.aureus - gram positive, catalase-positive, coagulase positive coccus

Question 4

2-to-5 um yeast with a thin cell wall but no true capsule

Answer 4

Histoplasma capsulatum

• central US, ohio, Mississippi, and Missouri river valleys.
• cavitary pulmonary lung disease, calcified lymph nodes

Question 5

4-10 um yeast with a broad, prominent capsule

Answer 5

Cryptococcus

-most common cause of fungal meningitis in immunosuppressed.

Question 6

10-60 um yeast with multiple budding surrounding the mother cell

Answer 6

Paracoccidioides - pulmonary disease in patients from South and Central America. Dissemination of infection can cause lymphadenopathy, hepatosplenomegaly and bone marrow dysfunction.

Question 7

20 to 60 um nonbudding spherules filled with endospores

Answer 7

Coccidoides immits = skin lesion of pulmonary disease in the desert southwest and far west of the united States. Dimorphic fungus with spherules with endospores. Which microscopically appear as 20 to 60 um nonbudding spherules filled with endospores

Question 8

Hyphae branching dichotomously at acute angles

Answer 8

Aspergillus fumigatus, an opportunistic fungus that can invade cavitary lesions in the lung and cause aspergilloma or fungus ball. It is a monomorphic filamentous fungus with dichotomous branching at acute angles. An early and transient finding on CT includes the presence of a nodular lesion with a surrounding halo.

Question 9

Gram negative bacillus- gram stain of sputum shows abundant neutrophils, aerobic cultures are blue/green.
How to treat?

Answer 9

Pseudomonas
characterized by antibiotic resistance and high mortality.
Double coverage - anti-pseudomonal beta lactam (piperacillin, tazobactam, cefepime, ceftazidime or for beta lactam allergic patients, aztreonam.
-a respiratory fluoroquinolone (levofloxacin, moxifloxacin, and gemifloxacin)
-aminoglycoside (gentamicin, tobramycin)

Question 10

23 yr old IV drug user has sudden high fever, severe dyspnea and malaise. One hour later he develops progressive respiratory distress and supplemntal oxygen is provided. His CD4 cell count is 188/microliter. Examination of fluid shows a predominant organism when stained with methenamine

Answer 10

Pneumocystis jirovecii

buzzwords
CD4 <200/microliter
-atypical fungus 
-dry cough 
-bilateral, interstitial infiltrates 
-CYSTS that are crushed tennis ball 
-methenmaine silver staining in BAL 
-TMP/SMZ - trimethoprim/sulfamethoxazole is prophylaxis and treatment.

Question 11

Patient is involved in near fatal fire. He develops pneumonia and progressive shortness of breath. Gram stain of sputum shows a gram negative, encapsulated, oxidase positive, aerobic rod. Resistance to aminoglycosides. What is allowing this resistance

Answer 11

Enzymatic inactivation

Pseudomonas aeruginosa - very common opportunist in burn patients.

Buzzwords, aminoglycoside resistance
-efflux systems that pump out antibiotics.

Question 12

Which of following organisms is unencapsulated? A. S. pneumoniae B. H. influenza type B C. N. meningitidis D. E. coli E. Salmonella sp F. K. pneumoniae G. S. agalactiae (GBS) H. Viridans streptococci I. P. aeruginosa

Answer 12

Viridans streptococci is not encapsulated. ALL other are encapsulated. Group A and Group B strep are encapsulated and slimy, allow it to colonize easier. The first three are very troublesome. Pseudomonas - the slimiest of slimy

SHINE my SKiS Please

Question 13

16 yr old girl has painful, enlarged lymph node in right axilla for week. Intermittent chills and subjective fevers for about 2 weeks. No other enlarged lymph nodes. Histologic examination shows granulomas filled with necrotic debris. What is the likely organism

Answer 13

Bartonella henselae - gram negative rod

-cats and dogs are reservvoirs that transmit through bites or scratches. This causes cat scratch fever which appears as regional lymphadenopathy with or without low grade fever and headaches.
-shows necrotizing/suppurative granulomatous response with foci of microabscesses.
=can cause bacillary angiomatosis - proliferative vascular form in immunocompromised and affect any organ system, usually skin and subcutaneous tissue
-treatment is azithromycin and doxycycline

Question 14

What are the five syndromes of Parvovirus

Answer 14

1. Erythema infectiosum (fifth disease) - slapped cheek rash
2. Aplastic crisis in individuals with chronic hemolytic disease (sickle cell, thalassemia)
3. Arthropathy
4. Pure red blood cell aplasia - immunocompromised individuals
5. Congenital infections - stillbirth, hydrops fetalis, severe anemia