Pharmacology of Renal Infections Flashcards
What are some characteristics associated with cases of complicated UTI?
Urinary obstruction
Urinary retention caused by neurologic disease
Immunosuppression
Renal failure
Renal transplant
Pregnancy
Foreign bodies (calculi, indwelling catheters)
—Indwelling catheters may be most common cause of complicated UTI
MCC of uncomplicated vs. complicated UTI
Uropathogenic E.coli causes majority of uncomplicated AND complicated UTI cases (but slightly less prevalent in complicated cases)
Other possibilities: K.pneumoniae S.saprophyticus Enterococcus spp. GBS P.mirabilis P.aeruginosa S.aureus Candida spp.
Components of biofilm formed by UPEC
Type 1 pili (essential!)
Antigen 43
Curli
What urea-producing organism forms crystalline biofilms associated with calcium and magnesium ammonium phosphate precipitates?
P.mirabilis
P.aeruginosa exhibits microcolony formation by changing hydrophobicity of its surface. What are the 2 main components of its biofilm?
Lectins
Rhamnolipids
What must be present for E.faecalis to cause catheter-associated UTI?
Fibrinogen — so UTI cannot be formed in vitro — need inflammatory response because fibrinogen acts as scaffold for bacteria to colonize
Tx for asymptomatic bacteriuria
Usually none is warrented
3 tx options for simple cystitis (first, second, and third line)
- Nitrofurantoin, TMP-SMX, fosfomycin
- Oral beta lactams (amoxicillin, cefpodoxime, cefdinir, cefadroxil)
- Fluoroquinolones (ciprofloxacin, levofloxacin, ofloxacin)
Nitrofurantoin is bactericidal for what bacterial species? What 2 are known to be resistant?
Nitrofurantoin is bactericidal for gram positive AND gram negative bacteria
P.aeruginosa and strains of Proteus are resistant
MOA of nitrofurantoin
Not fully understood
Conversion of nitrofurantoin into highly reactive intermediates by bacterial reductases — toxic intermediates react nonspecifically with many ribosomal proteins and disrupt synthesis of proteins, RNA, DNA, and metabolic processes
Nitrofurantoin is metabolized and excreted so quickly that no systemic antibacterial action is achieved, which is good because then it concentrates in the bladder. What are some AE’s, drug interactions, and contraindications associated with this drug?
AEs: anorexia, N/V
Interactions: antagonizes nalidixic acid (synthetic quinolone antibiotic)
Contraindicated in pts with G6PD deficiency (—> hemolysis)
What bacterial species is fosfomycin active against?
Gram positives AND gram negatives
MOA of fosfomycin
What causes resistance to this drug?
Cell wall synthesis inhibitor
Inhibits cytoplasmic enzyme enolpyruvate transferase by covalently binding to the cysteine residue fo the active site and blocking the addition of phosphoenolpyruvate to UDP-N-acetylglucosamine
Resistance is d/t inadequate transport of drug into cell
Fosfomycin is only available in oral form in the US. Its oral bioavailability is 40%, which is good because we don’t need systemic effects when treating cystitis. What are some adverse effects? Is it safe to use in pregnancy?
Limited AEs — HA and diarrhea
It is safe to use in pregnancy
T/F: nitrofurantoin and fosfomycin may be used in cases of suspicion for early pyelonephritis, as long as it is early case
False — if there is suspicion of early pyelonephritis must use something else because these drugs do not achieve adequate renal tissue levels
TMP-SMX is considered a first-line option for simple cystitis, however what is a situation in which you would avoid using it?
Avoid if prevalence if resistance is known to exceed 20%
Oral beta lactams are considered second line for simple cystitis. What drugs are used and what families do they fall into?
Amoxicillin — aminopenicillin
Cefpodoxime — 3rd gen cephalosporin
Cefdinir — 3rd gen cephalosporin
Cefadroxil — 1st gen cephalosporin
Oral beta lactams are ____ effective than fluoroquinolones and TMP-SMX
Less
[they are used before fluoroquinolones anyway because of the AEs associated with fluoroquinolones]
Fluoroquinolones utilized for cystitis include ciprofloxacin, levofloxacin, and ofloxacin. Which fluoroquinolone is NOT recommended, and why?
Moxifloxacin — attains lower urinary levels than the other fluoroquinolones
The FDA states that disabling and potentially irreversible AEs of systemic fluoroquinolones outweigh their benefits in treating uncomplicated cystitis. What are these AEs?
Tendonitis and tendon rupture
Peripheral neuropathy
CNS effects
Which drugs should NOT be used to empirically treat uncomplicated cystitis d/t possibility of drug resistance?
Ampicillin
Amoxicillin
If drug resistance is identified while treating uncomplicated cystitis, what drug is used, and what organisms is it effective/not effective against?
Ertapenem (a carbapenem)
As a class, the carbapenems have wide spectrum with good activity against gram negatives, gram positives, and anaerobes
However, ERTAPENEM specifically is NOT effective against P.aeruginosa
First and second line tx for pyelonephritis
- Fluoroquinolones (ciprofloxacin, levofloxacin)
2. TMP-SMX, oral beta lactam, aztreonam
First line defense for pyelonephritis is fluoroquinolones. If the case of pyelonephritis is severe, or if there are risk factors for drug resistance, they are administered with parenteral broad spectrum antibiotics like _____ or an aminoglycoside until susceptibility data is available
What 2 aminoglycosides are typically used?
Ceftriaxone
Aminoglycosides used are gentamycin and tobramycin