Urinary Tract Infections Flashcards
Cystitis vs pyelonephritis
Cystitis
- lower UTI or inflammation of the bladder
- presents with: hematuria, frequency/urgency, dysuria, pyuria, suprapubic pain
- DOESN’T usually present with systemic signs
- WBCs, nitrates and leukocyte esterase are all-found in the urine as well , but the CBC will look normal
Pyelonephritis
- upper UTI or inflammation of the kidney itself
- presents with: all cystitis symptoms + fever/chills, lower flank pain (CVA junction), N/V, hypotension
- infection counts in urine are present but WBCs are also elevated in the CBC (different from cystitis)
- also may show hyaline or WBC casts
**both are 10x more common in females
Risk factors for both cystitis and pyelonephritis
Being a women
- have shorter urethras and also receive urethral Trauma during sex
Frequent sexual intercourse (cystitis only)
- “honeymoon” cystitis in women and is usually staph saph
Kidney procedures
Catheterization (#1 risk factor)
Enlarged prostate
Obstruction of the tract
Pregnancy
- causes higher pH
Diabetes
- causes higher pH
Congenital defects
Frequent Post-void residuals
Having urethra bypass or indwelling catheter
What are the major UTI-causing pathogens?
E. Coli (#1)
Serratus marcescens
Proteus mirabilis
Pseudomonas aeruginosa
Klebsiella pneumoniae
Enterococcus species
**staphylococcus saprophyticus is only in women, but accounts for (5-15%)
ORENUC phenotype classification
**you give the UTI one of these letters based on the patient **
O: No risk factors
- patient is healthy and premenopausal
R: risk of recurrent UTIs
- patient has risky sexual behavior/uses spermicide, hormonal deficiencies (postmenopausal), well controlled diabetes
E: extra-urogenital risk factors are present
- premature new born, currently pregnant, male gender, poorly controlled DM, is immunosupressed
N: nephropathic diseases present with likely severe outcomes
- renal insufficiency, polycystic kidney disease, interstitial nephritis
U: resolvable/urological risk factors are present
- ureteral obstruction, asymptomatic bacteria, short-term external urinary catheter present, asymptomatic bacteremia
C: permanent external catheter is present or in resolvable urological risk factors
- irreversible neurogenic bladder
How are symptomatic UTIs classified?
By severity
The most severe = febrile UTI (urosepsis syndrome)
Guidelines for catheter care
note that because catheterization is the #1 risk factor for UTIs, it is essential to keep a patient on a catheter as little as possible
also bacteria that infect a catheter often produce biofilms which make antiseptic techniques not work as well
Avoid catheterization when possible
Keep duration to minimum
- each day on a catheter = Increases 3-10% chance
Use intermittent catheter rather than permanent whenever possible
Maintain a gravity drain
Use topical antiseptics around the meatus in women
Must use closed drain systems whenever possible
Common Bacterial virulence factors amoung UTIs
Fimbria/pill
- allow for adherence and increased hemolysin
- **bacteria that possess P fimbriae are far more likely to cause pyelonephritis
- **very common in e. Coli
# Capsular polysaccharide - K antigens and other antigens allows for anti-phagocytic properties
Ureases
- almost all have them and increases risks of kidney stones
- also allows them to live since urine is often toxic
IgA protease
Flagella
Endotoxins
- used to decrease ureteral peristalsis which allows easier time to retrograde migrate into the kidney
= most important and common virulence factors in UTIs
Acute lower UTI’s
Poorly understood immune response
- IgA and IgG are present but unknown why
- low serological response
Acute onset of dysuria/urgency and frequency will be present, usually no flank pain though and not severe suprapubic pain (but does show suprapubic pain)
- **elderly patients can be asymptomatic
Almost always shows pyuria and bacteriuria
- (+/-) hematuria
- usually labs dont show increased WBCs, but the urine dipstick will suggest UTI
Recurrent often causes fibrosis and metaplasia in the bladder
What are the two most common bacteria that can cause a UTI but NOT show up on UA cultures initially?
TB and chylamida
- both are rare causes of UTIs, but these two specifically dont show up well on UA cultures
also gonorrhoeae can cause this but is more rare
Acute upper UTIs
Difficult to distinguish from UTIs
- lower UTI symptoms + fever/chills and flank pain is the msot common method
- CBC = elevated WBC
- dipstick = signs of infection
Recurrent = loss of renal function
- leads to HTN and **chronic interstital nephritis (most dangerous)
Staph is more common in Upper UTIs, but still e.coli is #1
What populations are at risk for asymptomatic UTIs
Pregnant women
Young children
Elderly
Diabetics
will show hematuria with no symptoms
What is the cutoff for significant bacteriuria based on bacterial counts
10^5 (100,000 CFUs) or greater = significant bacteriuria
10^3 = not infected
In between = could have been contaminated but unknown
What is the cutoff for normal amounts of WBCs in urine?
<10mL
Common oral antibacterials used for UTIs
1) Trimethoprim
- good to use but has elevated resistance in some strains
- because of this often combined with sulphamethoxazole which combats the resistance
- TMP-SMX = often #1 used (CANT USE IN SULFA DRUG ALLERGIES THOUGH)
2) nitrofurantoin
- used in uncomplicated UTIs caused by E.coli add staph
- DONT use for urease positive organisms, it doesnt work (if the patients urine is alkaline = dont use)
3) fluroquinolones
- very broad spectrum and often a first line treatment
- doesnt work well against enterococcus however (use TMP-SMX if can)
usually use best guess until culture is obtained for specific organism
Most important pseudomonas aeruginosa virulence factors pertaining to UTIs
Exotoxins A:
- MOA = ADP-ribosylation of EF-2
- inhibits host cell protein synthesis
Phospholipases
- MOA = hydrolysis of phospholipids and Eukaroytic membranes
- casues tissue damage
Alginate
- MOA = adherence and protection from immune system and dehydration
Lipopolysacchrides
- MOA = protects against complement and allow induces sepsis via (O and lipid A antigens)
