UTI- Micro Flashcards
T/F Most UTI’s are caused by enteric bacteria
True
First line Ab in uncomplicated UTI’s
Nitrofurantoin or TMP-SMX for women
Fluroquinolone of TMP-SMX for men
Nitrofurantoin
Uncomplicated UTI’s and recurrent UTI’s
* NOT effective for Kidney infections*
Damages bacterial DNA by reactive intermediates
TMP-SMX (Bactrim)
UTI’s M/F, kidney infections
Stops the metabolism of folate- DHFR
Fluroquinolones
Broad coverage- gram + and gram -
First line for acute pyelonephritis or prostatitis (inpatient)
tendon rupture
Selective inhibition of topoisomerase II and IV- preventing unwinding and replication of DNA
UTI facts
More common in adults 20-50 yo
50x more likely in women
Factors that keep urinary tract free of infections
Acidity of urine
Urination- flushing
IHO and physical barriers to infection- mucosal lining of the tract and urethral sphincter
90% of UTI’s occur when…
bacteria ascends the urethra to the bladder or ureter to the kidney
** remainder are hematogenous in origin**
Complicated UTI’s
Underlying factors that predispose and individual to an ascending bacterial infection
- catheters, anatomic abnormalities, obstruction of flow or poor emptying (calculi, tumors, neurogenic, pregnancy, prostate, uterine prolapse and cystocele)
Uncomplicated UTI’s
Occurs without an underlying abnormality or impairment of flow
- unprotected intercourse, uncircumcised, diaphragm, spermicide, Ab use, history of recurrent UTI’s
Most common organism causing uncomplicated UTI’s
E.coli- 75%
Staph. saprophyticus 5-15% younger women
(Klebsiella, Proteus, Enterococcus, Citrobacter= 5-10%)
3 factors that lead to UTI’s
- Environment: urinary stasis, stones, catheters, vaginal ecology, anatomy, tissue-specific receptors
- Host: familial disposition, behavioral, receptors
- Microorganism: presence and expression of VF’s
Virulence Factors of E. coli
Surface adhesions which facilitate binding to epithelial cells to initiate colonization= P. fimbriae; Type 1 pilus is possessed but not always expressed in E. coli
Diagnosis of UTI
Analysis and culture of urine- can take up to 24 hours
Symptoms + bacteria, WBC’s and inflammatory cytokines
Asymptomatic bacteriuria ABU
Absence of symptoms but with presence of bacteria in the urine
E. coli
Gram -, bacilli, catalase +, oxidase -
Reduces nitrates to nitrites
Green metallic sheen on EMB agar
VF’s= pili, immune evasion with capsular Ag’s and flagella
Staph saprophyticus
Young, sexually active Females
gram + cocci
VF: adhesins and urease
Klebsiella pneumoniae
gram - rod, encapsulated, lactose-fermenting, facultative anaerobe
Produces urease
VF: pili, adhesins, immune evasion with capsule and flagella
Proteus mirabilis
???
Enterococcus faecalis
Gram + rod, catalase - facultative anaerobe GI tract Nosocomial & drug resistant VF: pili, adhesins, EPA
Pyelonephritis
E. coli= 90% of cases
Klebsiella
Enterococcus
ASB
ASB during pregnancy is associated with preterm birth and perinatal death of the fetus and with pyelonephritis in the mother
Males
75% have an anatomical abnormality- usually prostatic hypertrophy
Lack of circumcision is also associated with an increased risk of UTI because E. coli is more likely to colonize the glans and prepuce and subsequently migrate into the urinary tract.
Females and UTI’s
2-3 fold rate higher in diabetics for ABU and UTI- especially with insulin use
May have impaired cytokines