Urinary tract infection (UTI) is a common and
painful human illness that, fortunately, is rapidly
responsive to modern antibiotic therapy.
Epidemiology and risk factors
Between 1 year and 50 years of age, UTI and recurrent
UTI are predominantly diseases of females.
recent use of a diaphragm with spermicide
frequent sexual intercourse,
a new sexual partner,
a UTI in the previous 12 months
a maternal history of UTI
anatomic abnormalities affecting bladder
emptying, such as cystoceles, prostatic
hypertrophy, urinary incontinence, and residual urine
lack of circumcision
In acute uncomplicated cystitis
E. coli accounts for 75–90% of isolates;
Staphylococcus saprophyticus for 5–15% (with particularly
frequent isolation from younger women);
Klebsiella species, Proteus species, Enterococcus species,
Citrobacter species, and other organisms for 5–10%
In complicated UTI
E. coli (predominant organism)
Other aerobic gram-negative rods (such as Klebsiella species,
Proteus species, Citrobacter species, Acinetobacter species,
Morganella species, and Pseudomonas aeruginosa)
Gram-positive bacteria (e.g., enterococci and Staphylococcus
In the majority of UTIs, bacteria establish infection by
ascending from the urethra to the bladder.
Continuing ascent up the ureter to the kidney is the
pathway for most renal parenchymal infections.
Any foreign body in the urinary tract, such as a urinary
catheter or stone, provides an inert surface for bacterial
colonization. Abnormal micturition and/or significant
residual urine volume promotes true infection.
Hematogenous spread accounts for <2% of
documented UTIs (caused by relatively virulent
organisms, such as Salmonella and S. aureus.)
Pathogenesis of urinary tract infection. The relationship between
specific host, pathogen, and environmental factors determines the clinical
No local or systemic symptoms referable to
urinary tract but bacteriuria found incidentally
Dysuria, urinary frequency, urgency
Also nocturia, hesitancy, suprapubic
discomfort, gross hematuria may be present.
Unilateral flank or back pain indicates upper
urinary tract involvement
Fever indicates involvement of kidney / prostate.
High rise, spiking fever with
rigor, nausea, vomiting, flank and/or loin pain
[Low grade fever in mild cases ]
Rapid rise in creatinine may indicate papillary
Intraparenchymal abscess to be suspected
when patient has continued fever and/or
bacteremia despite antibacterial therapy
associated with production of gas in renal and
perinephric tissues in diabetics.
suppurative destruction of renal tissue from chronic
urinary obstruction [e.g. – by staghorn calculi] with
Emphysematous pyelonephritis. Infection of the right kidney of a diabetic man
by Escherichia coli, a gas-forming, facultative anaerobic uropathogen, has led to
destruction of the renal parenchyma (arrow) and tracking of gas through the
retroperitoneal space (arrowhead).
Xanthogranulomatous pyelonephritis.A. This photograph shows extensive destruction of
renal parenchyma due to long-standing suppurative inflammation. The precipitating factor was
obstruction by a staghorn calculus, which has been removed, leaving a depression (arrow). The
mass effect of xanthogranulomatous pyelonephritis can mimic renal malignancy. B. A large
staghorn calculus (arrow) is seen obstructing the renal pelvis and calyceal system. The lower
pole of the kidney shows areas of hemorrhage and necrosis with collapse of cortical areas.
Acute bacterial prostatitis presents with
dysuria, frequency, pain in the prostatic, pelvic or
perineal area,fever with chill and features of
bladder outlet obstruction
Chronic bacterial prostatitis presents with
recurrent episodes of cystitis
Symptomatic cystitis or pyelonephritis in a man or a
pregnant woman or a non-pregnant woman with an
anatomic predisposition to infection, with a foreign
body in the urinary tract, or with factors
predisposing to a delayed response to therapy.
In otherwise healthy non-pregnant women diagnosis
of cystitis and pyelonephritis can be done on the
basis of clinical presentation only!
Otherwise suggestive investigation findings are
positive dipstick test [detects nitrite]
positive leukocyte esterase test
pyuria in routine urine examination
hematuria (in 30% cases)
Urine culture is the diagnostic "gold standard" for UTI
Identifying specific organism(s) can require time
A colony count threshold of >102 bacteria/mL is very
much sensitive (95%) and specific (85%) for the diagnosis of
acute cystitis in women.
In men, the minimal level indicating infection appears to
To diagnose asymptomatic bacteriuria the cutoff is
usually 105 bacterial cfu/mL, except in catheter-
associated disease, in which case 102 cfu/mL is the cutoff.
Mixed bacterial growth may be due to
(i)contamination, (ii) long-term catheterization, (iii)
chronic urinary retention, or (iv) the presence of a fistula
between urinary tract and gastrointestinal/ genital tract.
Uncomplicated cystitis in women
The theme is to treat the infection with minimal
collateral damage [i.e. adverse ecologic effects of
antimicrobial therapy, including killing of the normal
flora and selection of drug-resistant organisms.]
Antibiotics that can be used are-
Fluoroquinolones [eg- ofloxacin, ciprofloxacin, levofloxacin etc]
Other drugs that may be added
urinary analgesics eg- phenazopyridine
Combination analgesics containing urinary antiseptics
(methenamine, methylene blue)
urine-acidifying agent (sodium phosphate),
antispasmodic agent (hyoscyamine)
Oral ciprofloxacin 500 mg twice daily for 7 days, (with or
without an initial IV 400-mg dose)
Oral TMP-SMX one double-strength tablet twice daily for 14
days (with an initial IV 1-g dose of ceftriaxone if susceptibility
Combinations of a beta-lactam and a beta-lactamase
inhibitor (e.g., ampicillin-sulbactam, ticarcillin-clavulanate
and piperacillin-tazobactam) or imipenem-cilastatin in
UTI in pregnancy
Ampicillin, cephalosporins and
nitrofurantoin are considered relatively safe.
UTI in men
7- to 14-day course of a fluoroquinolone or
TMP-SMX is recommended.
In chronic prostatitis, often warrant a 12-week
course of treatment.
Therapy to be individualised according to culture
Early percutaneous drainage and later elective
nephrectomy as needed
Asymptomatic bacteriuria to be treated in
persons undergoing urologic surgery
renal transplant recipients.
Catheter associated UTI (CAUTI)
7 to 14 days of antibiotic according to culture report
along with removal/ change of the catheter
“Avoidance is better than cure”
Removal of catheter if any
Drugs that may be used are
oral fluconazole (200–400 mg/d for 14 days)
oral flucytosine and/or parenteral amphotericin B