UTIs Flashcards
What causes UTIs?
Infection is most often due to bacteria from the patient’s own bowel flora
E. coli
What is an uncomplicated UTI?
Functionally normal urinary tracts (with normal renal imaging).
Here, persistent or recurrent infection seldom results in serious kidney damage
What is a complicated UTI?
Abnormal urinary tracts. Tracts with stones, or associated diseases such as diabetes mellitus which themselves cause kidney damage, may be made worse with infection
What are the signs of acute pyelonephritis?
The combination of fever, loin pain with tenderness and significant bacteriuria
Macroscopically, what can be seen on the kidney in pyelonephritis?
Small renal cortical abscesses and streaks of pus in the renal medulla are often present
Histologically, what can be seen in the kidney in pyelonephritis?
Focal infiltration by polymorphonuclear leucocytes and many polymorphs in tubular lumina
What is reflux nephropathy?
This was called chronic pyelonephritis or atrophic pyelonephritis, and it results from a combination of:
- vesicoureteric reflux, and
- infection acquired in infancy or early childhood.
In reflux nephropathy, what does the kidney look like?
Typically, there is papillary damage, tubulointerstitial nephritis and cortical scarring in areas adjacent to ‘clubbed calyces’
Diagnosis is based on CT scans
How is a UTI diagnosed?
This is based on quantitative culture of a clean-catch mid- stream specimen of urine and the presence or absence of pyuria
Dipstick tests positive for both nitrite and leucocyte esterase are highly predictive of acute infection
If you do a dipstick in a suspected UTI, what findings would confirm your diagnosis?
nitrite and leucocyte esterase
How would you manage a UTI?
3-5 day course
- amoxicillin (250 mg three times daily)
- nitrofurantoin (50 mg three times daily)
- trimethoprim (200 mg twice daily) or an oral cephalosporin.
What different antibiotics can be used for a UTI?
amoxicillin
nitrofurantoin
trimethoprim
What is the mechanism of action of amoxicillin?
Inhibition of cell wall biosynthesis and consequential cell death
What bacteria does amoxicillin work on?
Both gram pos and gram neg
What family of antibiotics is amoxicillin?
beta-lactam
What is a common side effect of amoxicillin?
Nonallergic rash
Maculopapular and starts at the trunk (72 hours after taking medication)
If someone develops a rash after taking amoxicillin, what do you suspect?
- Nonallergic rash
2. Infectious mononucleosis
What is the mechanism of action of nitrofurantoin?
Nitrofurantoin is broken down inside the bacterial cell, and the its intermediates attack ribosomal bacterial DNA, leading to cell death
What is the mechanism of action of trimethoprim?
Trimethoprim binds to dihydrofolate reductase and inhibits the reduction of dihydrofolic acid (DHF) to tetrahydrofolic acid (THF). THF is an essential precursor in the thymidine synthesis pathway and interference with this pathway inhibits bacterial DNA synthesis
How would you manage a patient with acute pyelonephritis?
Aztreonam, cefuroxime, ciprofloxacin or gentamicin
What class of antibiotics is Aztreonam?
Monobactam
What type of bacteria does Aztreonam mainly target?
Gram neg
What is the mechanism of action for Aztreonam?
It inhibits synthesis of the bacterial cell wall, by blocking peptidoglycan crosslinking
(penicillin like)
What sort of bacterium is E. coli?
gram-negative, rod-shaped bacterium
What class of antibiotics is cefuroxime?
Cephalosporin
What is the mechanism of action for cefuroxime?
Cephalosporins disrupt the synthesis of the peptidoglycan layer forming the bacterial cell wall
What type of antibiotic is ciprofloxacin?
fluoroquinolone
What is the mechanism of action for ciprofloxacin?
It functions by inhibiting a type II topoisomerase (DNA gyrase) and topoisomerase IV, necessary to separate bacterial DNA, thereby inhibiting cell division.
What bacteria does ciprofloxacin work against?
Gram positive and gram negative
What type of antibiotic is gentamicin?
Aminoglycoside antibiotic
What is the mechanism of action for gentamicin?
Gentamicin is a bactericidal antibiotic that works by binding the 30S subunit of the bacterial ribosome, negatively impacting protein synthesis
The primary mechanism of action is generally accepted to work through ablating the ability of the ribosome to discriminate on proper transfer RNA and messenger RNA interactions
