Page 270 - Medicine and Surgery
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                   266 Chapter 6: Genitourinary system


                     in cell membranes. E. coli also inhibits phagocytosis.     Urinary stones for example, Proteus, through the pro-
                     Urease is produced by some organisms (e.g. Proteus),  duction of urease, causes the alkalinisation of urine, so
                     it hydrolyses urea and increases ammonia, which fa-  that phosphate, carbonate and magnesium are more
                     cilitates bacterial adherence.               likely to precipitate to form struvite stones.
                     Host predisposing factors include any functional or  Bacteraemia can lead to septicaemia and in vulnerable

                     anatomical abnormality of the urinary tract such  hosts, infective endocarditis.
                     as urinary stasis, reflux or stones. Other important
                     risk factors include sexual intercourse, diabetes melli-
                                                                Investigations
                     tus, immunosuppression, instrumentation (including
                                                                Mid-stream urine for urinalysis (dipstick testing), mi-
                     catheterisation) and pregnancy.
                                                                croscopy, culture and sensitivity. A culture is regarded as
                     Urine itself is inhibitory to the growth of normal uri-  5

                                                                positive if >10 of a single organism per mL.
                     nary flora (non-haemolytic Streptococcus corynebacte-
                                                                  Patients with systemic symptoms should have a blood
                     ria, Staphylococcus) through its pH and chemical con-
                                                                culture, FBC and differential, U&Es and creatinine to
                     tent.
                                                                look for dehydration and any evidence of renal impair-
                                                                ment. Further investigations are required in children
                   Clinical features
                                                                (see page 268), males and females with recurrent infect-
                   Acute cystitis typically presents with dysuria (a burning
                                                                ions.
                   pain on passing urine), urgency and frequency. Fever
                   and other systemic features are variable. Macroscopic
                   haematuria is not uncommon, although this should  Management
                   prompt further investigation for any other underlying  Empirical antibiotic therapy is used in symptomatic pa-
                   disease such as urinary stones or a bladder malignancy.  tients, until culture and sensitivity results are available.
                   Pyelonephritis may present with few lower urinary tract  Uncomplicated cystitis in a woman usually only requires
                   symptoms, but more commonly causes systemic upset  3daysoforal antibiotics, whereas longer courses are re-
                   withfever,rigors,chills,andloinpainortenderness.Pro-  quired in complicated cases, e.g. those with urinary sta-
                   statitis causes fever, malaise and pain in the perineum  sis, indwelling catheters, pyelonephritis and prostatitis.
                   and lower back as well as dysuria and frequency. Both  Intravenous antibiotics should be used in those who are
                   pyelonephritis and prostatitis may be due to ascending  systemically unwell or those who are vomiting.
                   or haematogenous infection (usually ascending).     Commonlyuseddrugsincludetrimethoprim,amoxy-
                     UTIs in pregnancy, the elderly and those with in-  cillin and co-amoxiclav (as many infections are

                     dwelling catheters may be asymptomatic, or may  caused by β-lactamase producers). Quinolones such
                     present nonspecifically with fever, falls, vomiting, or  as ciprofloxacin are useful as resistant E. coli and Pro-
                     confusion etc.                               teus are uncommon, but they do not adequately cover
                                                                  gram-positive organisms.
                   Macroscopy                                       Intravenoustherapyisoftenwithacephalosporinwith
                   The urine is cloudy due to the pyuria (pus cells) and  or without gentamicin.
                   bacteriuria, and may contain visible amounts of blood  Oral fluids should be encouraged where possible to pre-
                   (macroscopichaematuria).Sterilepyuria(puscellswith-  vent dehydration and relieve symptoms. Cranberry juice
                   out a positive culture) may be caused by antibiotic treat-  may also have a role in reducing symptoms, but has not
                   ment, stones, drugs such as NSAIDs and occasionally  been shown to be effective in treatment or prevention of
                   tuberculosis.                                UTIs.
                                                                  Recurrent UTIs may be reduced, e.g. by passing urine
                   Complications                                after intercourse, treatment of stones and in some cases
                     Recurrent infections which may be relapses or a re-  prophylactic antibiotics. These may cause microbial re-

                     infection. Over time, recurrences can cause chronic  sistance, and some centres advise a ‘cycling regime’, e.g.
                     inflammatory changes in the urinary tract (bladder,  of three different antibiotics, each used for 1 month to
                     prostate).                                 prevent this.
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