Flashcards in L78 – Drugs used in urinary tract infection Deck (63):
Name the infection of bladder, urethra, prostate and upper urinary tract?
Urethra = Urethritis
Prostate = Prostatitis
Upper urinary tract = Pyelonephritis
Most common causative agent of Catheter-associated UTI?
Most common pathogens for urethritis?
Klebsiella pneumoniae is 100% resistant to ?
Proteus mirabilis is 100% resistant to ?
Quantitative cultures may be optional before treatment of what UTI?
typical acute uncomplicated cystitis
Culture urine in patients with which UTI?
upper UTI / complicated UTI / treatment failure
What testing is done in all recurrent or complicated UTI?
What is the guideline for FIRST LINE antibiotic use in acute Uncomplicated UTI in female adults?
nitrofurantoin (7 days, oral)
amoxicillin-clavulanate (7 days, oral)
Why is nitrodurantoin used for acute Uncomplicated UTI in female adults?
Low local resistance rate
Less likely to select drug-resistant organisms
What is the guideline for SECOND LINE antibiotic use in acute Uncomplicated UTI in female adults?
Bacteria that cause Acute cystitis?
Group B streptococcus
What is the guideline for FIRST LINE antibiotic use in uncomplicated UTI in children?
1st-line: cefuroxime / co-trimoxazole
Which drugs are not recommended for infants under 3 months old with UTI?
co-trimoxazole, nitrofurantoin, nalidixic acid
What precaution is taken when treating children younger than 3 with UTI?
igher chance of recurrent infection
>> consider antibiotics prophylaxis after
What is the guideline for Asymptomatic Candiduria UTI due to Candida spp?
Eliminate predisposing factors, e.g. remove bladder catheters
DO NOT treat with local / systemic antifungal agents unless patient belongs to high-risk group for
dissemination (e.g. Neutropenic patients)
What is the guideline for Symptomatic Candiduria UTI due to Candida spp?
For fluconazole-susceptible organisms: oral fluconazole
For fluconazole-resistant species: AmB deoxycholate, Oral flucytosine
What is the guideline for Symptomatic ascending Candida pyelonephritis due to Candida spp?
fluconazole-susceptible organisms: oral fluconazole
AmB deoxycholate, oral flucytosine
What do Azoles inhibit?
inhibit synthesis of
ergosterol from lanosterol >> inhibit formation of cell membrane
What do Polyenes (e.g. amphotericin B) inhibit?
to ergosterol = cannot form
membrane (impaired integrity)
What does Flucytosine inhibit?
inhibits DNA/RNA synthesis
Treatment of Candida UTI associated with Fungus Ball?
Adults: surgical intervention
Cystitis / pyelonephritis: anifungal treatment
What are the 2 Chlamydial infections?
What is the empirical treatment for Chlamydial infections?
Azithromycin (oral daily)
Doxycycline (orally twice daily for 7 days)
What is the empirical treatment for Chlamydial infections if the patient is pregnant??
use azithromycin instead of Doxycycline
WHat are alternative drugs for Chlamydial infections?
tetracycline / erythromycin / ofloxacin
WHat are adverse drug reactions from Chlamydial infection drugs?
mostly gastrointestinal (mild to moderate)
What is Gonococcal infections?
urethritis (purulent discharge), cervicitis
What bacteria causes Gonocaccal infections?
Could be penicillin- and tetracycline-resistant strains
What is the empirical therapy for penicillin- and tetracycline-resistant strains of Neisseria gonorrhoeae?
1) Single IM injection of ceftriaxone
2) Single oral dose of azithromycin
Which drugs are no longer the first line for gonococcal infections and why?
Increased resistance to oral cephalosporins / fluoroquinolones = no longer 1st-line
Always treat for what infection when treating gonococcal infection?
Always treat also for Chlamydia when treating for gonorrheae (usually infected by both)
What is caused by unsuccessful treatment of gonococcal infections?
Unsuccessful treatment can cause pelvic inflammatory disease
What is the preferred drug for treating prostatitis? Why?
quinolones (e.g. ciprofloxacin, levofloxacin)
- high tissue penetration,
mainly excreted into urine
Alternative drugs to quinolones for treating prostatitis?
clarithromycin, azithromycin, doxycycline
What additional therapeutic effects arise from drugs treating prostatitis?
anti-inflammatory and/or anti-neuropathic effect
How do Non-beta-lactams inhibit cell wall synthesis? (e.g. Vancomycin, Bacitracin?
inhibit early steps of
peptidoglycan synthesis (not cross-linkage)
Extended spectrum penicillins are effective against which bacteria? Sensitive to what?
Effective vs. many Gram
–ve bacilli in UTI, bacteremia, skin infections.. etc
Sensitive to Beta-lactamase, acid labile
What is the drug combo used to counter act B-lactamase produced by bacteria?
ß-lactamase inhibitors (prevent hydrolysis of β-lactam ring, irreversible)
What are the 4 preparations of B-lactam + B-lactamase inhibitors?
Augmentin® (amoxicillin +
Unasyn® (ampicillin +
Timentin® (ticarcillin +
Tazocin® (piperacillin +
Apart from Beta-lactamase, name another mechanism of resistance against Beta-lactams?
Change in structure of transpeptidase to bind less effectively to B-lactam antibiotics
MoA of Macrolides and Tetracyclines?
Tetracyclines: blocks tRNA binding to ribosome (30S)
Macrolides: bind to P site >> inhibit polypeptide chain to be translocated from A to P site
What does Aminoglycosides interfere with in bacteria?
binds to 30S ribosome >> disrupt protein synthesis
Apart from macrolides, name some other 50s inhibitors?
Name 2 antibiotics that inhibit folate synthesis in bacteria?
Both structurally similar to folate intermediates of DNA synthesis
MoA of sulfamethoxazole?
structural analog of para-aminobenzoic acid (PABA)):
synthesis of dihydrofolic acid from PABA
MoA of Trimethoprim?
structural analog of a potion of dihydrofolic acid):
competitively inhibits synthesis of
tetrahydrofolic acid (precursor of DNA, RNA and proteins)
Are folate inhibitors bacteriostatic or cidal?
What is the synergistic ratio for inhibiton of folate synthesis? Why?
Cotrimoxazole: Trimethoprim/ Sulmethoxazole ratio
>> sequential blockade in folic acid synthesis
Adverse effects of folate synthesis inhibitors?
Skin rash, Megaloblastic anaermia, Haemolytic anaemia (in patients with G6PD deficiency)
Name antibiotics that inhibit DNA and RNA synthesis?
RNA = Rifampin/ Riframpicin
DNA = Metronidazole, Quinolones
Metabolized to unstable molecule with DNA
>> DNA breaks > inhibit DNA synthesis
MoA of quinolones?
bind to gyrase- / topoisomerase IV-DNA complex
>> inhibit DNA unwinding during replication >> block DNA synthesis
Name some 1st and 2nd gen quinolones?
1st = nalidixic acid
2nd = ciprofloxacin, ofloxacin
Name some 3rd and 4th gen quinolones?
3 = Levofloxacin
4 = Gemifloxacin
When is Nitrofurantoin taken and not taken?
Taken: For uncomplicated UTI, prophylaxis for recurrent UTI
Not taken: for pyelonephritis due to low tissue penetration
Resistance, serum and urine levels of Nitrofurantoin?
Low rate of resistance (due to many mechanisms of action)
Serum level low
Concentrated in urine
Harmless side effect of Nitrofurantoin?
Brown urine, but harmless
MoA of Nitrofurantoin?
Nitrofuran reductase activates nitrofurantoin
produce reactive intermediates (free radicals) to attack:
What is Fosfomycin? MoA?
>> irreversibly inhibits enolpyruvate transferase (MurA) to prevent formation of NAM for cell wall
WHat is the gold standard for bacteria?
antibiotic susceptibility testing:
agar diffusion test >> zone of inhibition
What is the new method of identifying bacteria?
sequence bacterial DNA >> identify a few fingerprint region of bacteria >> compare with database to assess susceptibility