Nejm 2003;349:259; Jags 1996;44:1235 (elderly)
Cause:(K. Holmes—Nejm 1980;303:409): 70% due to coliforms at >105/cc in urine; 11%, coliforms at <105/cc in urine; 5%, Chlamydia trachomatis;1%, Staph. saprophyticus(often misread as Staph. epidermidisor albusby labs); 4% (Jama 1999;281:736), gc;H. simplex;MRSA emerging as a significant pathogen, especially in those institutionalized and with h/o catheter use (Urolo 2009;181:1694)
Pathophys:Recurrent disease, due to a possible inherent defect in epithelial cell membrane leading to easier adherence by bacteria (Nejm 1986;314:1208; 1981;304:1062)
Incidence, up to perhaps 20% of all women get each year; increased with catheters, mostly from perimeatal invasions of urethra along outside of catheter (Nejm 1980;303:316); increased with sexual activity, history of previous episodes, and spermicides + diaphragm use (Nejm 2000;343:992; 1996;335:468), also in pregnancy; not prevented by various hygiene habits except voiding after sex (Ann IM 1987;107:816)
Sx:
Dysuria, frequency; stuttering onset over days with chlamydia type
OTC home kits specific but quite insens, many false negs
Many resolve without rx and many are subclinical (asx) (Nejm 2000;343:992); catheter-induced UTIs have 2-4 times the mortality of non-catheter-induced UTIs (Nejm 1982;307:637) and only 1/3 resolve after removal without rx, 90% will with single dose or 10 d rx (Ann IM 1991;114:713)
r/o vaginitis, herpes, and subclinical pyelo, which can dx when it relapses eventually; reflux nephropathy in children w renal US + VCUG debatably w 1st documented UTI; chronic interstitial (idiopathic) cystitis (Med Let 1997;39:56)
Lab:
Bact:Culture of midstream urine (clean catch unnecessary—Nejm 1993;328:289), >105 organisms in only 50% of truly infected women with sx; 102 a better criterion when sx (Ann IM 1993;119:454; Holmes—Nejm 1982;307:463)
Urine:UA shows pyuria, >5-6 wbc/hpf (10% false neg, 50% false pos when have sx—Nejm 1982;307:463); hematuria (often not with chlamydia); dipstick nitrite tests have high false-pos rates so cultures much better (Ped Infect Dis J 1991;10:651). Sens/specif of all such tests vary greatly by pretest likelihood, eg, w <5 wbc’s/hpf, sens/specif both = 60%, if >5 wbc, sens is 100%, specif 22% (Ann IM 1992;117:135)
Xray:IVP and cystoscopy of no value to workup recurrent UTIs in adult women (Nejm 1981;304:462)
Rx:
Prevent in postmenopausal women w recurrent UTIs w estriol 0.5-mg cream (Ovestin) qd × 2 wk then biw, helps without significant estrogen absorption (Nejm 1993;329:753)
Prevent in pregnancy, elderly with cranberry juice qd (Urolo 2008;180:1522)
Prophylaxis w Tm/S 1/2 a single strength (40/200) pill qd hs (Nejm 1974;291:597), or postintercourse; is cost effective if 
3 UTIs/yr (Ann IM 1981;94:250)
Antibiotics (Med Let 1999;41:98):
- Regular rx of a UTI: Tm/S single strength bid, ciprofloxacin 250 mg po bid or other fluoroquinolone, or amoxicillin 250-500 mg po tid × 7-10 d, if no gonorrhea, chlamydia, or vaginitis (Nejm 1981;304:956). 20% resistance to cephalothin, sulfa, amoxicillin (Jama 1999;281:736)
- 3-day regimens in uncomplicated patients also reasonable (Ann IM 1989;111:906), eg, Tm/S DS bid × 3 d gives 82% cure vs 67% cure for amoxicillin 500 mg po bid × 3 d (Jama 1995;273:41); or a fluoroquinolone
- Single-dose regimens: Tm/S 160/800 (DS), 1-2 pills (1st choice—Ann IM 1988;108:350), as good when take prn at home as prophylactic use (Ann IM 1985;102:302); amoxicillin 2-3 gm po; or sulfasoxazole 1-2 gm po
Bladder anesthetics: phenazopyridine (Pyridium) 200 mg po tid × 2 d; stains urine dark orange
of asx bacteriuria, no rx indicated, although it correlates w worse prognosis; rx does not improve (Ann IM 1994;120:827)
of catheter-associated UTI: d/c catheter if can, rx if sx; can’t clear UTI if catheter still in place