The uri­nary tract com­pris­es the kid­neys, ureters, blad­der, and ure­thra. A uri­nary tract in­fec­tion (UTI) is an in­fec­tion caused by bac­te­ria, fun­gi or par­a­sites in any of the struc­tures that com­prise the uri­nary tract. UTIs are com­mon, more com­mon in women than men, lead­ing to ap­prox­i­mate­ly 8.3 mil­lion doc­tor vis­its per year. Al­though some in­fec­tions go un­no­ticed, UTIs can cause prob­lems that range from dy­suria (pain and/or burn­ing when uri­nat­ing) to or­gan dam­age and even death.

The kid­neys are the ac­tive or­gans that, dur­ing their av­er­age pro­duc­tion of about 1.5 quarts of urine per day, func­tion to help keep elec­trolytes and flu­ids (for ex­am­ple, potas­si­um, sodi­um, wa­ter) in bal­ance, as­sist re­moval of waste prod­ucts (urea), and pro­duce a hor­mone that aids to form red blood cells. If kid­neys are in­jured or de­stroyed by in­fec­tion, these vi­tal func­tions can be dam­aged or lost. While some in­ves­ti­ga­tors state that UTIs are not trans­mit­ted from per­son to per­son, oth­er in­ves­ti­ga­tors dis­pute this and say UTIs may be con­ta­gious and rec­om­mend that sex part­ners avoid re­la­tions un­til the UTI has cleared. There is no dis­pute about UTIs caused by sex­u­al­ly trans­mit­ted dis­ease (STD) or­gan­isms; these in­fec­tions (gon­or­rhea, chlamy­dia) are eas­i­ly trans­mit­ted be­tween sex part­ners and are very con­ta­gious.

UTI caus­es and risk fac­tors

The most com­mon caus­es of UTI in­fec­tions are Es­cherichia coli bac­te­r­i­al strains that usu­al­ly in­hab­it the colon. How­ev­er, many oth­er bac­te­ria can oc­ca­sion­al­ly cause an in­fec­tion. There are many risk fac­tors for UTIs. In gen­er­al, any in­ter­rup­tion of the usu­al flow of urine is a risk fac­tor for a UTI. For ex­am­ple, kid­ney stones, ure­thral stric­tures, en­larged prostate. This is due in part to the flush­ing or wash-out ef­fect of flow­ing urine

Peo­ple who re­quire catheters have an in­creased risk (about 30 per cent of pa­tients with in­dwelling catheters get UTIs) as the catheter has none of the pro­tec­tive im­mune sys­tems to elim­i­nate bac­te­ria and of­fers a di­rect con­nec­tion to the blad­der.

There are re­ports that sug­gest that women who use a di­aphragm or who have part­ners that use con­doms with sper­mi­ci­dal foam are at in­creased risk for UTIs. In ad­di­tion, fe­males who be­come sex­u­al­ly ac­tive seem to have a high­er risk of UTI; some in­ves­ti­ga­tors term these UTIs as "hon­ey­moon cys­ti­tis." Men over 60 have a high­er risk for UTIs be­cause many men at or above that age de­vel­op en­larged prostates that may cause slow and in­com­plete blad­der emp­ty­ing. Oc­ca­sion­al­ly, peo­ple with bac­te­ria in the blood­stream have the in­fect­ing bac­te­ria lodge in the kid­ney. Sim­i­lar­ly, peo­ple with in­fect­ed ar­eas that are con­nect­ed to the uri­nary tract are more like­ly to get a UTI. Ad­di­tion­al­ly, pa­tients who un­der­go uro­log­ic surgery al­so have an in­creased risk of UTIs. Preg­nan­cy does not ap­par­ent­ly in­crease the risk of UTIs ac­cord­ing to some clin­i­cians; oth­ers think there is an in­creased risk be­tween weeks six through 26 of the preg­nan­cy. Pa­tients with chron­ic dis­eases such as di­a­bet­ics or those who are im­muno­sup­pressed (HIV or can­cer pa­tients) al­so are at high­er risk.

What are UTI symp­toms and signs?

The UTI symp­toms and signs may vary ac­cord­ing to age, sex, and lo­ca­tion of the in­fec­tion in the tract. Some in­di­vid­u­als will have no symp­toms or mild symp­toms and may clear the in­fec­tion in about two to five days. Many peo­ple will not spon­ta­neous­ly clear the in­fec­tion; some of the most fre­quent signs and symp­toms ex­pe­ri­enced by most pa­tients is a fre­quent urge to uri­nate, ac­com­pa­nied by pain or burn­ing on uri­na­tion. The urine of­ten ap­pears cloudy and oc­ca­sion­al­ly red­dish if blood is present. The urine may de­vel­op an un­pleas­ant odour. Women of­ten have low­er ab­dom­i­nal dis­com­fort or feel bloat­ed and ex­pe­ri­ence sen­sa­tions like their blad­der is full. Women may al­so com­plain of a vagi­nal dis­charge, es­pe­cial­ly if their ure­thra is in­fect­ed, or if they have an STD. Al­though men may com­plain of dy­suria, fre­quen­cy, and ur­gency, oth­er symp­toms may in­clude rec­tal, tes­tic­u­lar, pe­nile, or ab­dom­i­nal pain. Tod­dlers and chil­dren with UTIs of­ten show blood in the urine, ab­dom­i­nal pain, fever, and vom­it­ing along with pain and ur­gency with uri­na­tion. (med­i­cinenet.com)