Diversity and Complexity of Urinary Tract Infection in Diabetes Mellitus

Anatomical Spectrum of Infection

UTIs invariably enter via the ascending route. Asymptomatic bacteriuria has been reported to be commoner in women with diabetes, although data are less convincing for men.^[4,5] Many studies have also shown that bacteriuria in diabetic women involves the upper urinary tract more frequently.^[6,7] However most authors believe that asymptomatic bacteriuria in patients with diabetes does not lead to complications and therefore screening and treatment is not warranted, except perhaps in pregnant women.^[8,9,10]

Acute pyelonephritis is a common presentation of UTI in diabetes. In one study by Nicolle et al.^[11] diabetes increased the probability of acute pyelonephritis requiring hospital admission by 20–30-fold in those under 44 years of age and by three to five-fold in men and women aged 45 years and over. Not only do patients with diabetes have an increased incidence of acute pyelonephritis compared with non-diabetic controls, but bilateral pyelonephritis is also commoner and predisposes to more severe infection of the upper urinary tract with substantially greater complications.

Bacteraemia is four times more likely to occur from UTIs in patients with diabetes than in non-diabetic controls. Acute renal failure is twice as likely to develop in bacteraemic patients.^[4,12] This may be related to the additional presence of diabetic nephropathy. Metastatic Gram-negative infections are also commonly reported. Endophthalmitis, osteomyelitis, particularly of the vertebrae, septic arthritis, abscesses and bacteraemic Gram-negative pneumonia are the commonest metastatic complications arising from UTI.^[13,14,15] Figures 1a and 1b illustrate a case of Gram-negative pneumonia as a complication of urinary sepsis in diabetes. The primary burden of acute pyelonephritis, however, occurs within the kidney itself with the commonest complications being acute papillary necrosis, emphysematous pyelonephritis and renal abscesses.^[4,16,17]

(Enlarge Image)

Figure 1.

(a) Chest X-ray (CXR) showing bilateral extensive consolidation in a 47-year-old woman with type 1 diabetes presenting with right-sided pyelonephritis. Admission CXR showed clear lung fields. Blood cultures and mid-stream urine isolated E. coli. Despite receiving piperacillin/tazobactam 4.5 g three times daily the patient deteriorated 3 days after admission when E. coli pneumonia due to metastatic spread of organisms was diagnosed. Gentamicin was added to the antibiotic regime and the patient improved after a brief period in the intensive care unit (b) CT scan showing bilateral consolidation and pleural effusion more marked on the left side

Emphysematous pyelonephritis is a gas-forming infection of the renal parenchyma, perinephric tissues, and collecting system. It is almost exclusively an infection of diabetic patients and carries a grave prognosis. Papillary necrosis complicates 21% of cases.^[18,19] Intra-renal and perinephric abscesses are a collection of suppurative material that can pose a great diagnostic challenge, as the presentation is often insidious (figure 2). In one series of patients with perinephric abscess, 36% had diabetes.^[20]

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Table 1. Causative organisms and treatment of urinary tract infection in patients with diabetes
Infection	Common Organisms	Antimicrobial Therapy	Further Management and Comments
Acute bacterial cystitis	E. coli, Proteus species	Trimethoprim 200 mg ^2x Ciprofloxacin 500 mg ^2x 7–14-day course	Early surgical intervention in emphysematous infection Consider ESBL if no clinical improvement
Acute pyelonephritis	E. coli, Proteus species	Ciprofloxacin 500 mg/400 mg ^2x or third generation cephalosporins or piperacillin/tazobactam 4.5 g^3x 7–14-day course If ESBL suspected meropenem 500 mg/1 g^3x	Emphysematous infection should be considered
Emphysematous pyelonephritis	E. coli, K. pneumoniae	As above	Emergency nephrectomy often required
Perinephric and intra-renal abscess	E. coli and other Gram-negative bacilli (associated with pyelonephritis) S. aureus (associated with bacteraemia)	As above but consider adding flucloxacillin 1 g/2 g i.v. if S. aureus suspected	Surgical drainage
Fungal cystitis	Candida species (C. albicans, C. glabrata, C. tropicalis)	Fluconazole 100 mg^2x 7–14 days (Amphotericin B bladder irrigation or single dose i.v. amphotericin)	Removal of urinary catheter
Fungal pyelonephritis and abscesses	Candida species (C. albicans, C. glabrata, C. tropicalis)	Fluconazole 6 mg/kg/day prolonged therapy (2–6 weeks ) or i.v. amphotericin	Surgical drainage Removal of stents and relieve obstruction if any