*1.2.1. Recurrent urinary tract infections*

Urinary tract infections (UTIs) are the second most common infections in humans (Foxman 2002). A UTI is the presence of microorganisms in the urine (not due to contamination) which can invade the urinary tract or adjacent structures. It is well established the route of infection is ascending in most cases of infections with enteric bacteria which explains why UTIs are more common in females. The development of a UTI is determined by the balance between bacterial virulence, size of the inoculum, local defence mechanisms and anatomical or functional alterations of the urinary tract (Andreu, Cacho et al. 2011).

It is estimated that the prevalence of UTIs in sexually active young women is 0.5-0.7 episodes per year. One fourth of these will recur. Eighteen out 10000 of these women will develop pyelonephritis and 7% will require hospitalization (Andreu, Cacho et al. 2011). This is despite the fact that most young women with UTI have normal urinary tracts (Hooton 2001). The development of infection is determined by the balance between bacterial virulence, size of the inoculum, local defence mechanisms and anatomical or functional alterations of the urinary tract.

Recurrent UTIs are defined as 3 or more culture-documented infections in 1 year or 2 or more in 6 months in women without structural or functional abnormalities. (Grabe, Bjerklund-Johansen et al. 2011).

Risk factors that predispose to UTIs abnormalities of the urinary tract (such as urinary incontinence or obstruction), sexual behaviour, use of contraceptives, postmenopausal hormonal deficiency, asymptomatic bacteriuria and past urinary tract surgery (Grabe, Bjerklund-Johansen et al. 2011). Risk factors for recurrent UTIs in postmenopausal institution‐ alised women include atrophic vaginitis, incontinence, cystocele and post-voiding residual urine and a history of UTI before menopause (Nicolle 1997). Collagen diseases represent another extra-urogenital risk factor.

Systemic diseases, mainly diabetes mellitus and chronic renal failure are also important risk factors (Sharifi, Geckler et al. 1996). Women with diabetes mellitus are prone to UTIs. UTI in both diabetic men and women is more likely to progress to pyelonephritis. Patients with type 1 diabetes and UTIs can develop renal damage with time. This is more likely in the presence of proteinuria and peripheral neuropathy. Risk factors for renal damage in women with type 2 diabetes mellitus and recurrent UTIs include old age, proteinuria and low body mass index (Geerlings, Stolk et al. 2000 ). In addition, autonomic neuropathy may cause bladder dysfunc‐ tion(Korzeniowski 1991).

In the presence of risk factors, bacterial strains of low virulence can cause UTIs. These risk factors predispose to recurrence but do not affect outcome.

Prevention of recurrent UTIs should avoid the use antibiotics given the alarming rise in antibiotic resistance observed worldwide (Fihn 2003; Grabe, Bjerklund-Johansen et al. 2011).Antibiotic prophylaxis should only be used after counselling and behaviour modifica‐ tion has been attempted (Grabe, Bjerklund-Johansen et al. 2011). Other measures to prevent recurrences include immune active prophylaxis (Lorenzo-Gómez, MF et al. 2013), probiotics and cranberry juice.
