18. Metronidazole. Fidaxomicin. Rifaximin. Urinary antiseptics. Phosphomycin

Question 1

Fidaxomicin

Answer 1

Protein synthesis inhibitor

• ​Inhibits RNA polymerase - disruption of transcription
• Bacteri​cidal
• narrow , (G+) (c.difficile)
• Oral
• ——————————————————————————–G​I (nausea, vomiting)
• hypersensitivity

Question 2

Rifaximin
(​R​ifampicin​ group)

Answer 2

• Interacting with DNA dependent ​RNA polymerase
• semisynthetic, rifamycin-based non-systemic antibiotic.
• ​G(+) (staphylo, strepto, enterococcus)
• G(-) (m​oderate action​ against the intestine bacteria)
• O​ral administration does no absorb from the GI!​!
• H​epatic encephalopathy,
• Prophylaxis before ​colorectal surgery​,
• Acute(noninflammatory) Enteritis​(drug of choice),
• C​olitis

Question 3

Urinary antiseptics

Answer 3

Methenamine
Decomposes to formaldehyde in acidic pH
(toxic for bacteria)

• oral
• C​hronic suppressive therapy for UTI
• G​I distresses
• ——————————————————————————-Nitrofurantoin

Damages bacterial DNA- reduced to highly active intermediates

-uncomplicated lower UTI
(in pregnancy, in children, in case of resistance)
———————————————————————————G​I symptoms
-hypersensitivity pulmonary reaction

Question 4

Phosphomycin

Answer 4

Cell wall synthesis inhibitor ​

(Inhibits the first step in formation of UDP-N-acetylmuramic acid)

• Bacteri​cidal
• ​G( +) and G (-) (ESBL E.coli), E.faecalis

-oral or parenteral
(no minimal 7 days administration - maintaining concentration in the urine)

• GI symptoms

Question 5

Metronidazole

Answer 5

-free radical metabolites disrupt bacterial DNA
(form free radicals) Bactericidal

• Coverage of polymicrobial anaerobic infections (intra-abdominal infections)
• activity against Entamoeba histolytica (liver abcess)
• activity against giardia
• treats vaginitis and cervicitis caused by protozoal infection(treat both patient and partner)
• treats bacterial vaginosis caused by gardenella
• substitute for amoxicillin in the triple therapy for helicobacter pylori infection in penicillin allergic patients
• activity against anaerobic bacteria
  (bacteroides, prevotta, fusobacterium, clostridium)
• treats pseudomembranous colitis caused by clostridium
• Clindamycin above the diaphragm, metronidazole below