Microbiology

Question 1

How are the plasmodium organisms transmitted?

Answer 1

Anopheles Mosquito

Question 2

Classic Presentations of Plasmodium

Answer 2

Malair, fever, headache, anemia, splenomegaly

Question 3

What are the fever cycles of the different plasmodium?

Answer 3

Falciparum: irregular
Vivax/Ovale: 48h cycle
Malariae: 72h cycle

Question 4

How are plasmodium vivax/ovale and falciparum presented differently?

Answer 4

P. falciparum: severe; irregular fever patterns; parasitized RBCs occlude capillaries in brain (cerebral malaria), kidneys, lungs
P. vivax/ovale: 48 hr cycle; dormant form in liver

Question 5

What are the diagnosis findings of plasmodium?

Answer 5

Blood smear, trophozoite ring form. RBC schizont with merozoites

Question 6

Treatment for plasmodium (first line and resistant)

Answer 6

Chloroquine (blocks plasmodium heme polymerase)
Resistant, use mefloquine
Vivax/ovale: add primaquine for dormant form in liver (hypnozoite)

Question 7

Babesia. Transmission, Presentation, Diagnosis and Treatment

Answer 7

Ixodes Tick (NE US). Fever and hemolytic anemia. Asplenia increase risk of severe disease.
Blood smear, ring form, “Maltese cross”
Quinine, clindamycin

Question 8

Lyme disease. Pathogen. Transmission. Presentation (Stages). Treatment

Answer 8

Borrelia burgdorferi (Ixodes tick, mice/deer, NE US). Large, microaerophilic spirochete. 
 Stage 1: erythema chronicum migrans (bull's eye red rash with central clearing), flulike symptoms. Stage 2: Bell's palsy, cardiac (AV nodal block). Stage 3: chronic monoarthritis, migratory polyarthritis. Doxycycline, ceftriaxone

Question 9

Ehrlichiosis. Pathogen/Transmission. Presentation.

Answer 9

Lone Star tick. Granulocytes with berry cluster organisms. No Rash

Question 10

Wuchereria bancrofti. Transmission, Presentation, Treatment

Answer 10

Mosquito. Blockage of lymphatic vessels (elephantiasis). 9mo-1y after bite for symptoms. Diethylcarbamazine

Question 11

Rocky Mountain Spotted Fever. Pathogen, Transmission, Presentation

Answer 11

Dermacentor tick (east coast). Rickettsia rickettsii (obligate intracellular). Classic triad of headache, fever and rash (vasculitis). Starts on palms and soles.

Question 12

Tularemia. Pathogen, Transmission, Presentation

Answer 12

Francisella tularensis (intracellular Gram negative bacterial rod). Dermacenter tick/deer fly, rabbits.

Question 13

Plague. Pathogen, Transmission

Answer 13

Yersinia pestis (intracellular Gram negative enterics). Flea bite, rodents, prairie dogs.

Question 14

What is genetic shift (reassortment)?

Answer 14

Viruses with segmented genoms (e.g. influenza virus) exchange segments. Cause of worldwide influenza pandemics.

Question 15

What is viral complementation?

Answer 15

When 1 of 2 viruses that infect the same cell has defect. The nonmutated one “complements” the mutated one by making a functional protein that serves both viruses.

Question 16

What is genetic drift?

Answer 16

Random mutational changes; can change surface of organism affecting host immune response. Changes more gradual than shift (e.g. HIV)

Question 17

What is viral phenotypic mixing?

Answer 17

2 related viruses infect same cell and capsid produced is a mixture of both parents. Since genomic RNA is not reassorted, progeny has only one coat from parent.

Question 18

What is phenotypic masking?

Answer 18

2 related viruses infect single cell. Capsid produced is created from genome of other virus, but genome is different.

Question 19

What are the picoRNAviruses?

Answer 19

PEECoRnA viruses
Polio, Entero, Echo, Coxsachie, Rhino, hep A

Question 20

What are the positive-sense RNA viruses?

Answer 20

Calicivirus, Hepevirus, Picornavirus, Flavivirus, Togavirus, Coronavirus, Retrovirus

Question 21

Hand-foot-mouth disease. Agent and presentation

Answer 21

Cosackievirus type A (picornavirus), vesicular rash on palms and soles; ulcers in oral mucosa.

Question 22

What viruses have double stranded DNA?

Answer 22

Herpesviruses (linear), hepadnavirus (partial circular), adenovirus (linear)

Question 23

What viruses are single stranded DNA?

Answer 23

Parvovirus (linear), Papillomavirus (circular), Polyomavirus (circular), Poxvirus (linear, largest)

Question 24

Which viruses are negative-stranded RNA?

Answer 24

Arenaviruses, Bunyaviruses, Paramyxoviruses, Orthoyxoviruses, Filoviruses, Rhabdoviruses

Question 25

What is floppy-baby syndrome?

Answer 25

Infant botlusim (clostridium botulinum). honey to infants; toxin ingestion from spores, generated in intestine and carried by blood to CNS
 Flaccid paralysis - blocking ACh release at cholinergic synapses. oxin encoded in genome of temperate phage (lysogeny)

Question 26

Botulism Toxin. Pathogen, Presentations

Answer 26

Clostridium botulinum (G+, spore-forming, obligate anaerobic bacilli). Produces preformed, heat-labile toxin (bacteriophage) that inhibits ACh release at NMJ, causing botulism. In adult - disease caused by ingestion of preformed toxin. Babies, ingestions of bacterial spores in honey causes disease - reversible floppy baby syndrome)

Question 27

What is the mechanism of vancomycin resistance?

Answer 27

Vancomycin: inhibits cell wall mucopeptide formation by binding D-ala D-ala portion of cell wall precursors (bacteriocidal). Used for G+
Resistance from enterococci using D-lactic acid instead. (plasmid mediated)

Question 28

What are some drugs that are susceptible to:
enzymatic (acetylation) deactivation, altered drug-binding protein, beta-lactamase, decreased ribosomal binding, formation o f novel cell-wall peptide?

Answer 28

a. aminoglycosides, chloramphenicol, sulfonamides; b. penicillin; c. penicillins and cephalosporins; d. protein synthesis-inhibiting antibiotics-tetracycline, minocycline, doxycycline, macrolide antibiotics; e. vancomycin

Question 29

What infection has the classic pseudomembrane on oral and nasal mucosa

Answer 29

Corynebacterium diphtheriae (inhibits eEF-2, inhibiting protein synthesis); extremely contagious; also cause laryngeal palsy and lower limb polyneuritis