id: uti Flashcards
Enterobacteriacae
gut gram -ve bacilli:
- E.coli
- Klebsiella
- Proteus
pathogenesis - 2 routes of infection
- ascending: colonic/fecal flora colonise periurethra area/urethra > ascend to bladder and kidney
- higher risk in females (shorter urethra), use of spermicides, diaphgrams as contraceptives
- gut bacteria - hematogenous (descending): organism at distant primary site eg. heart valve, bone > travels to bloodstream (bacteremia) > urinary tract > UTI
- S.aureus, Mycobacterium tuberculosis
host defense mech
- bacteria in bladder stimulates micturition with incr diuresis > emptying of bladder
- antibacterial properties of urine and prostatic secretion
- anti-adherance mechanisms of bladder, prevent attachment
- inflammatory response with PMNs > phagocytosis
risk factors for UTI
- female>male
- sexual intercourse
- abnormalities of the urinary tract eg. prostatic hypertrophy, kidney stones, urethral strictures, vesicoureteral reflux
- neurologic dysfunctions eg stroke, dm, spinal core injuries
- anticholinergic drugs
- catheterisation and other mechanical instrumentation
- pregnancy
- use of diaphragms and spermicides
- genetic association (pos fhx)
- previous uti
non-pharmaco for prevention of uti
- drink lots of fluid, flush the bacteria: 6-8 glasses a day
- urinate frequently and go when you first feel the urge, bacteria can grow when urine stays in the bladder too long
- urinate shortly after sex, flush away bacteria that might have entered the urethra during sex
- for women, after using the toilet, alw wipe from front to back esp after bowel movement
- wear cotton underwear and loose-fitting clothes so that air can keep the area dry, avoid tight-fitting jeans and nylon underwear which trap moisture and can help bacteria grow
- modify birth control method: stay away from diaphgram or spermicide, unlubricated condoms or spermicidal condoms incr irritation which may help bacteria grow
presence of complicating factors
- men
- children, pregnant
- functional and structural abnormalities of urinary tract
- genitourinary instrumentation
- dm
- immunocompromised host
lower UTI subj sx
- dysuria: pain
- urgency
- frequency
- nocturia
- suprapubic heaviness or pain
- gross hematuria
upper UTI subj sx
- fevers
- rigors
- headache
- n/v
- malaise
- flank pain
- costovertebral tenderness (renal punch)
- or abdominal pain
when to obtain cultures
- pregnant women
- recurrent uti (relapse within 2 weeks or freq)
- pyelonephritis
- catheter-associated uti
- all men with uti
not necessary in uncomplicated cystitis
objective signs (UFEME)
- WBC>10/mm3: pyuria, signifies presence of inflammation but may or may not be due to infection
- RBC, presence: hematuria: non-specific
- microorg: identify bacteria or yeast strain using gram stain
- WBC casts: masses of cells and proteins that form in the renal tubules in kidneys, indicate upper tract infection or disease
objective signs (chemical urinalysis/dipstick)
- nitrite: gram neg, reduces nitrate to nitrite
(false neg results due to presence of gram pos org and P.aeruginosa, low urinary pH, freq voiding and dilute urine) - leukocyte esterase: presence of leukocytes in urine, correlates with significant pyuria
likely pathogen for uncomplicated uti
85%: E.coli
5-15%: Staphylococcus saprophyticus, common coloniser of urinary tract
Others: Enterococcus faecalis (+ve), klebsiella, proteus
likely pathogen for complicated or healthcare-associated uti
50% E.coli
Enterococci (+)
Proteus, klebsiella, enterobacter (-v), p.aeruginosa
healthcare-assoc risk factors
- hospitalisation in the last 90 days
- current hospitalisation >= 2 days
- residence in nursing home
- antimicrobial use in last 90 days
- home infusion therapy
S.aureus
commonly due to bacteremia, consider other primary site of infection
Yeast or candida
possible contaminant, consider other primary site of infection
need to treat UTI?
yes if symptomatic
no if asymptomatic, except for:
- pregnant women: treatment reduces development of pyelonephritis and risk of preterm labour and low birth weight infant
- patients going for invasive urologic procedures with mucosal trauma eg. TURP cystoscopy with bipsy: abx given as prophylaxis to prevent postoperative bacteremia and sepsis > obtain culture then start abx based on culture and sensitivity 12-24hrs before procedure
empiric abx for cystitis
first line:
PO co-trimoxazole 800/160mg BD x3d
PO nitrofurantoin 50mg QDS x5d
PO fosfomycin 3g ONCE
alt:
beta lactams x3-7d
PO cefuroxime 250mg BD
PO cephalexin 500mg BD
PO augmentin 625mg BD
FQ x3d
PO cpiro 250mg BD
PO levo 250mg OD
complicated - 7-14d, fosfo 3g EOD x 3 doses
empiric abx for pyelonephritis
first line:
PO cipro 500mg BD x7d
PO levo 750mg OD x5d
alt:
PO co-trimox 800/160 BD x14d
PO cephalexin 500mg BD x10-14d
PO amoxi-clav 625mg TDS x10-14d
empiric abx for pyelonephritis, severely ill pt
IV cipro 400mg BD or IV cephazolin 1g q8h or IV amoxi-clav 1.2g q8h
AND/OR
IV gentamicin 5mg/kg (ESBL)
- switch to oral when pt improved or able to take orally
empiric abx for uti in men
treat as per complicated cystits in women
but if cystitis w concern of prostatitis or pyelonephritis:
- PO cipro 500mg BD x10-14d
- PO co-trimoxazole 800/160 BD x10-14d
treat for longer duration if prostatitis is confirmed: 6 weeks
nosocomial
onset of uti > 48hrs post adm
healthcare associated
pt who have been hospitalised or underwent invasive urological procedures in the last 6 months, has an indwelling urine catheter, etc.
empiric abx for nosocomia/healthcare-associated pyelonephritis
possibility of P.aeruginosa and other resistant bacteria (ESBL-producing E.coli and Klebsiella):
- IV cefepime 2g q12h +/- IV amikacin 15mg/kg/d
- IV imipenem 500mg q6h or mero 1g q8h
- PO levo 750mg OD
- PO cipro 500mg BD
x7-14d
risk factors for development of catheter-associated uti
- duration of catheterisation
- colonisation of drainage bag, catheter and periurethral segment
- dm
- female
- renal function impairment
- poor quality of catheter care, including insertion
empiric abx for catheter-associated UTI
IV imipenem 500mg q6h or mero 1g q8h
IV cefepime 2g q12h +/- iv amikacin 15mg/kg (1dose)
PO/IV levo 750mg x5d (for mild ca-uti)
PO co-trimoxazole 960mg BD x3d (women =< 65yo, without upper uti sx, after an indwelling catheter has been removed)
x7d (prompt resolution of sx, in 72hrs) and 10-14d for those with delayed response
prevention of catheter-associated uti
- avoid unnecessary catheter use
- use for minimal duration
- long-term indwelling catheters changed before blockage is likely to occur
- use of closed system
- ensure aseptic insertion technique
- topical antiseptic or antibiotics not recommended
- prophylactic abx and antiseptic not recommended
- chronic suppressive abx not recommended
abx choices for uti in pregnancy
avoid cipro
avoid co-trimoxazole in 1st and 3rd trimester
avoid nitrofurantoin near term (38-42wks)
use aminoglycosides with caution
why do we have to avoid cipro during pregnancy?
reports of fetal cartilage damage and arthropathies in animal studies and occasional human case reports in children
why do we have to avoid co-trimox during pregnancy?
1st as folate antagonsim of tmp can cause neural tube defects, close term due to theoretical risk of kernicterus (hyperbilirubinemia) in newborns from competitive binding btw bilirubin and sulfonamides to plasma albumin
- concern for fetus being g6pd-deficient
why must avoid nitro in pregnancy?
concerns for fetus being g6pd-deficient
why must use AO w caution in pregnancy?
8th cranial nerve toxicity in fetus reported with older AO: kanamycin, streptomycin
not reported with newer AO so far
how long to treat uti in pregnancy?
7d for asymptomatic
14d for pyelonephritis
which abx to avoid in pt w altered cardiac conduction?
cipro (FQ, QTc prolongation)
which abx to use in caution for pt at risk of seizures
cipro
which abx might cause crystalluria
co-trimoxazole, adequate hydration - hence avoid use in CrCl<15ml/min
which abx causes dark-coloured urine
nitrofurantoin
urogesic
phenazopyridine 100-200mg TDS
- azo dye, exerts a topical analgesic effect on the urinary tract mucosa to provide symptomatic relief
- tx limited to duration of sx
- do not use in g6pd deficiency
- adr: n/v, orange-red discolouration of urine and stool
urine alkalinisation
relief discomfort in mild uti, unproven benefit
cranberry juice
cranberry proanthocyanidine
- inhibits adherence of E.coli to urinary tract epithelial cells
- clinical data suggestive of efficacy in decr incidence of uti
- but many limitations to existing studies, need more reliable evidence
Intravaginal estrogen cream
remains controversial
- decr incidence of uti in postmenopausal women
- restores vaginal flora, prevents colonization with E. coli
lactobacillus probiotics
- restore normal vaginal flora and have protective effect against E.coli colonisation
- recent small controlled trial showed intravaginal lactobacillus reduced recurrence uncomplicated cystitis
- promising but more reliable evidence needed
