Folate Antagonist

Question 1

Lower urinary tract infection

Answer 1

Cystitis

Question 2

Symptoms of Cystitis

Answer 2

Painful + frequent urination

Question 3

Upper urinary tract infection

Answer 3

Pyelonephritis

Question 4

What microorganism causes both lower+ upper UTI?

Answer 4

Escherchia coli

Question 5

Why is UTI common in females?

Answer 5

Women’s urethra is shorter making them prone to infection

Question 6

What does E coli cause?

Answer 6

UTI (entry from GIT to UT)

GASTROENTERITIS (eating infected food contaminated with pathogenic strains)

Question 7

What is Escherchia coli?

Answer 7

Gram-negative, Coliform (any bacteria found in large intestines), rod-shaped, enteric bacteria
It forms natural flora of mammalian GI tract

Question 8

What is the pathogenicity mediated by?

Answer 8

O-polysaccharide
Polysaccharide shell
Lipid A - causes Toxic shock

Question 9

Virulence Factors

Answer 9

Outer membrane - protection from phagocytosis
Fimbriae/Adhesins - attach to epithelial cells
Exotoxins
Iron-binding proteins - acquire Fe needed for growth
Haemolysins - release Fe from blood cells
Type III secretion system builds an insertion (needle) to inject proteins into host cells

Question 10

What is the first line treatment for simple UTI?

Answer 10

Trimethoprim

Question 11

What is the second line for UTI?

Answer 11

Nitrofurantoin

Question 12

What is the treatment for Urosepsis/Pyelonephritis?

Answer 12

IV Co-amoxiclav / Cefuroxime

Gentamicin

Question 13

What to use for folate metabolism?

Answer 13

Sulphonamides, Trimethoprim, Pyrimethamine

Question 14

What makes up folate?

Answer 14

Folic acid + Vit B9

Co-factor for all living cells

Question 15

What is the use of folate?

Answer 15

In mammals, it is used during phases of rapid cell division e.g. pregnancy + infancy

Question 16

Function of reduced form ‘Tetrahydrofolate’

Answer 16

A carrier of single fragments used to make adenine, guanine, thymine and methionine

Question 17

How to make folate?

Answer 17

One molecule of pteridine + p-ABA (p-aminobenzoic acid) + glutamic acid = dihydropteric acid.
Dihydropteric acid reduce to tetrahydrofolate by dihydrofolate reductase

Question 18

What are Sulphonamides + function?

Answer 18

Structural analogue p-ABA
Inhibit addition of pABA into the folate (dihydropteric acid)
Clinical use decreased due to bacterial resistance

Question 19

Examples of drugs in Sulphonamides class

Answer 19

Sulfamethoxazole, Sulfadiazine

Question 20

What drug can you have with sulfamethoxazole + why?

Answer 20

Trimethoprim because they exhibit synergistic activity
Sulfamethoxazole + Trimethoprim = Co-trimoxazole
Prescribed to treat urinary and respiratory infections

Question 21

What is Trimethoprim?

Answer 21

Selective inhibitor of bacterial DHFR
Structural analogue of Dihydropteric acid + fits into DHFR active site normally by DHF forming hydrogen bonds with amino acid + water lining active site

Question 22

How does trimethoprim resistance occur?

Answer 22

Occurs as a result of overproduction of DHFR by bacteria

Acquire dfr gene encodes resistant form of enzyme - commonly DHFR I, II, III amongst enterobacteria

Question 23

Can mammals make DHF?

Answer 23

No so it needs to be supplied through diet and then reduced in liver

Question 24

Symptoms of pyelonephritis

Answer 24

Fever
Lower back pain
Painful + frequent urination

Question 25

Folate

Answer 25

Folic acid + Vitamin B9

Question 26

What organism can make folate?

Answer 26

Bacteria