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Urinary Tract Infection- Adults

A urinary tract infection is defined by a combination of clinical features and the presence of bacteria in the urine ( NICE 2014 )

Bacteriuria –bacteria present in urine- shown by culture or microscopy

Asymptomatic bacteriuria ( ABU ) –bacteria present in urine- shown by culture or microscopy

UTI -significant bacteriuria and characteristic symptoms and signs of UTI ie dysuria , frequency , suprapubic tenderness , urgency ,polyuria , haematuria

Lower UTI Infection of bladder Cystitis – used synonym for lower UTI
( technically inflammation of bladder and can be non- infectious )

Upper UTI –Includes pyelitis – infection of proximal part of ureters and
Pyelonephritis – infection of kidneys and the proximal part of ureters

Recurrent UTIs- Repeated UTI due to 
Relapse ( same strain within a short period eg 2 weeks ) or 
Reinfection ( different strain or species more than 2 weeks after treatment )

Uncomplicated UTI- UTI by usual pathogen with a normal urinary tract and normal kidney function-further differentiated as lower UTIs ( cystitis ) and 
upper UTIs ( pyelonephritis )

Complicated UTI –UTIs associated with factors that compromise the UrTr or host defense ( these include urinary obstruction , urinary retention due to neurological disease , immunosuppression , renal failure, renal transplantation , pregnancy and FB presence as calculi , indwelling catheters or other drainage devices )

Epidemiology –UTIs are the most common bacterial infections affecting 150 million people each year worldwide Incidence is highest among young women , about 10-20 % of women experience a symptomatic UTI at some time One of the commonest acute reason why adult females seek healthcare In adult men- most infections are complicated and related to abnormalities of the urinary tract – although some can happen without any obvious reason in otherwise healthy young men Incidence of UTI increases with age ( in both sexes ) Incidence is higher in older adults with diabetes and in very frail Studies ( three ) of care home residents has shown that UTI account for 29 % , 47 % and 6 6 % of all antibiotic preparations Asymptomatic bacteriuria is common in people over 65 ( about 10 % of men and 20 % women ) Significant economic burden – in USA estimated overall cost of UTI is about $ 3.5 Billion/year-hospital admission for UTIs it appears are increasing in the US and UK A large population base study ( of nearly 1 million older adults ) has shown an increase in the incidence of clinically diagnosed UTI between 2004-2014, we need further studies to understand why this happened and measures for prevention and improved diagnostic .

Pathogenesis –Uropathogens have specialized characteristics like production of adhesins , siderophores and toxins which enable them to colonize and invade the UrTr Important events in UTI pathogenesis are
- periurethral colonization
- progression to the urethra and migration to the bladder
- in the bladder the host-pathogen interactions eventually decide if the uropathogen is successfully eliminated or leads to colonization Escherichia Coli are the most common pathogen in uncomplicated UTI ( often labeled uropathogenic E Coli -UPEC ) Other common pathogens include Klebsiella pneumoniaea , Proteus mirabilis , Enterococcus faecalis and Staphylococcus saprophyticus Sepsis happens if the pathogen crosses the tubular epithelium barrier in the kidney


Risk factors- Sexual behaviour and contraceptive devices Hormonal deficiency in post menopause Secretory type of certain blood groups Controlled diabetes mellitus Pregnancy Male gender Badly controlled diabetes Relevant immunosuppression Connective tissue diseases Prematurity , new-born Relevant renal insufficiency Polycystic nephropathy Urethral obstruction
stone , stricture Transient short term catheterization Asymptomatic bacteriuria Controlled neurogenic bladder dysfunction Urological surgery Long term urinary catheter treatment Non resolvable urinary obstruction Badly controlled neurogenic bladder

Differential diagnosis- Overactive bladder Herpes genitalis ( HSV ) N.Gonorrhoeae Chlamydia Cancer of bladder and upper urinary tract Vaginitis Prostatitis Nephrolithiasis Trauma Urinary tract tuberculosis Urinary tract neoplasm Intra-abdominal abscess Sepsis- other than GU system Foreign body in bladder Asymptomatic bacteriuria.

Reuesting MSU –Asymptomatic elderly with positive dipsticks – do not send MSU routinely
 Two or more signs of infection – particularly dysuria , fever > 38° C or new incontinence –> send MSU
 Asymptomatic bacteriuria- common in elderly do not treat.

Men and women with catheter –Indwelling catheter and asymptomatic bacteriuria – very common do not treat Only send MSU for culture in catheterized if features of systemic infection – however always
○ exclude other sources of infection
○ check if catheter functioning properly
○ consider need for continued catheterisation
○ if catheter in place > 7 Days consider changing ir before / when starting antibiotic

When else should you request MSU –Pregnancy – see UTI in pregnancy topic Suspected pyelonephritis Suspected UTI in men Failed treatment or persistent symptoms
○ E coli with ESBL and CPE enzymes are increasing in community
ESBL- extended-spectrum beta-lactamase
CPE- carbapenemase producing enterobacteriaceae
ESBLs are multi-resistant but usually remain sensitive to nitrofurantoin or fosfomycin Recurrent UTIs , abnormalities of GU tract or renal impairment –> more likely to have resistant strains

Discussion-BJGP paper reports that only about 2/3rd of females said they actually took the antibiotics as prescribed The same paper reports that between 34-60 % of those receiving antibiotics have negative urine culture Serious complications of UTI includes recurrence ,pyelonephritis with sepsis , renal damage in young children , pre-term birth and antibiotic resistance Studies have shown that in UK trimethoprim was consistently the most commonly prescribed antibiotic for community acquired UTI accounting for about 50 % of all antibiotic scripts Resistance to UPEC is rising Empirical evidence for optimal antibiotic duration in older men is limited A study in US has shown that most elderly women receive antibiotic for longer ( > 3 days ) despite no difference in outcome shown in trials High rate of recurrent UTIs indicate that antibiotics are not an effective therapy for all UTIs ( other treatment for e.g FimH vaccines are being studies )


  1. SIGN 88. Management of suspected urinary tract infection in adults July 2012
  2. Guidelines on Urological Infections
    M. Grabe (Chair), R. Bartoletti, T.E. Bjerklund Johansen,
    T. Cai (Guidelines Associate), M. Çek,
    B. Köves (Guidelines Associate), K.G. Naber,
    R.S. Pickard, P. Tenke, F. Wagenlehner, B. Wullt European Association of Urology
  3. Diagnosis of urinary tract infections ( UTIs ) Public Health England Quick reference guide for primary care : For consultation and local adaption June 2017 via
  4. Which treatment strategy for women with symptoms of urinary tract infection ? BMJ 2015 ; 351:h 6888
  5. NICE CKS Urinary tract infection ( lower )- women July 2015
  6. Urinary Tract Infection ( UTI ) and Cystitis ( Bladder Infection ) in Females – eMedicine June 2017
  7. Adult UTI accessed via
  8. BMJ Best Practice Urinary Tract Infection in Women
  9. Urinary tract infections in adults NICE quality standard
    Draft for consultation
    November 2014
  10. Flores-Mireles, A. L., Walker, J. N., Caparon, M., & Hultgren, S. J. (2015). Urinary tract infections: epidemiology, mechanisms of infection and treatment options. Nature reviews. Microbiology, 13(5), 269–284.
  11. Foxman, B. The epidemiology of urinary tract infection. Nat Rev Urol 7, 653–660 (2010). Abstract
  12. Incidence, severity, help seeking, and management of uncomplicated urinary tract infection: a population-based survey
    Chris C Butler, Meredith KD Hawking, Anna Quigley, Cliodna AM McNulty
  13. Incidence and antibiotic prescribing for clinically diagnosed urinary tract infection in older adults in UK primary care, 2004-2014 Haroon Ahmed, Daniel Farewell, Hywel M. Jones, Nick A. Francis, Shantini Paranjothy, Christopher C. Butler Published: January 5, 2018
  14. Epidemiology of Antibiotic Use for Urinary Tract Infection in Nursing Home Residents Thompson, Nicola D. et al. Journal of the American Medical Directors Association, Volume 21, Issue 1, 91 – 96


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