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Flashcards in Microbiology Deck (16):
1

Which cocci are gram positive and which are negative?

Which basili are gram positive and which are negative?

Most cocci are gram positive EXCEPT 

  • n meningiditis
  • n gonorrhoea
  • m catarhalis

Most bacili gram negative EXCEPT

  • clostridium spp
  • bacillus spp
  • listeria
  • corynebacertium diptheriae
  • proprionibacterium
  • mycobacterium

2

What cell type is this?

Eosinophil

3

What cell type is this?

Basophil

4

What cell type is this?

Lymphocyte

5

What cell type is this?

Neutrophil

6

What cell type is this?

Monocyte

7

Which of the following vaccines is least likely to induce long term immunologic memory?
A) Bacille Calmette-Guérin (BCG).
B) Diphtheria-tetanus-pertussis.
C) Haemophilus influenzae type B conjugate.
D) Hepatitis B.
E) Pneumococcal polysaccharide.

Pneumococcal polysaccharide
Pneumococcal polysaccharide vaccine is available for children aged 2 years and older as younger children are unable to mount an appropriate immune response to the non-conjugated vaccine (or actual pneumococcal disease).
Most healthy older people respond well to the vaccine, but those in groups at high risk of invasive pneumococcal disease may exhibit a poor immune response. It is unclear how long the antibody response lasts and most people will require a second vaccination after 3-5 years depending on age.
High risk children less than 5 years of age would generally be given both the polysaccharide and the conjugated vaccine for maximum protection.

8

What organism is most likely to cause purulent otitis media?

Strep Pneumoniae

9

MOA aminoglycosides

Aminoglycasides - binding to the 30S ribosomal subunit – bacteriocidal to Gram Negatives – peak concentration killing.

10

MOA macrolides

Macrolides - bind to the 50S subunit of bacterial ribosomes – Resistance (i) alteration in ribosomal proteins (ii) macrolide efflux pump

11

MOA Quinolones

Quinolones - direct inhibitors of bacterial DNA synthesis (Fluoroquinolones inhibit DNA gyrases). Resistance - mutation in chromosomal genes

12

MOA tetracyclines

Tetracyclines – binds 30S ribosomal subunit - bacteriostatic effect.

13

MOA Vancomycin

Vancomycin - Inhibits bacterial cell wall synthesis by blocking glycopeptide polymerization – VRE Vancomycin resistance gene cluster – ALTERS vanc binding site to low affinity site.

14

MOA Trimethoprim-sulfamethoxazole

Trimethoprim-sulfamethoxazole: Folate synthesis inhibition (Reduced availability of THF inhibits thymidine synthesis and subsequently DNA synthesis) Resitance – decreased perm and efflux.

15

MOA Linezolid

Linezolid: Inhibits bacterial protein synthesis by binding to bacterial 23S ribosomal RNA of the 50S subunit.

16

MOA Penicillins/Beta lactams

Penicillins/Beta Lactams – inactivating enzymes located in the bacterial cell membrane, which are involved in the third stage of cell wall synthesis.

Enzymes = penicillin binding proteins (PBPs).

Bactericidal by autolytic enzymes.

Resistance:  

  • Alterations in PBPs (Pneumococcus, MRSA, gonococci, enterococci, and Haemophilus influenzae)  
  • Production of beta-lactamase (Chromosomal: Gram negatives, Plasmid: Cephalosporin cleavage) 

Carbapenems (ß-lactam, ie meropenem) – resist beta-lactamases; Beta-Lactamase Inhibitors