Overview · Diabetes mellitus (DM) · Chronic kidney

Overview

Urinary tract
infections (UTIs) are a common condition seen both in hospital and the
community setting. They are predominantly caused by Gram-negative bacilli
(70%), and Escherichia coli is the most common pathogen. Certain conditions associated
with a higher risk of UTIs are shown in Table 1. These conditions may
deteriorate the host defensive mechanism or allow a bypass route for pathogens
in the urinary tract.1

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Table
1: Conditions associated with risk of UTI

Conditions
associated with higher risk of UTI

UTI
within the past 12 month

Underlying
urologic abnormalities

Diabetes
mellitus

Sexual
activity in women

Age

Urinary
interventions

Urinary
catheters

 

The most common
acquired conditions causing deterioration in host defence mechanisms are:1

·        
Diabetes mellitus (DM)

·        
Chronic kidney diseases

·        
End stage renal disease

·        
Solid organ transplantation
(specifically kidney transplantation).

Urine conditions that increase
susceptibility to urinary pathogens are as mentioned below:1

·        
Urinary pH between 6 and 7

·        
Glucosuria

·        
Idiopathic hypercalcuria

·        
Elevated urinary iron

Females are prone to
UTIs due to the shortness of the urethra, which is close to the vagina and
anus; the lack of prostatic fluid, which has antibacterial activity; or the use
of spermicides and/or diaphragms.2

Chronic kidney disease
(CKD) may result from recurrent UTIs and retrospective infection to the
kidneys. Chronic kidney disease (CKD) has already become a burden of global
health. With advances in hemodialysis and medical care, patients sustaining CKD
have had prolonged survival. Even so, these patients may have some medical
problems that cause CKD, such as diabetes mellitus (DM), uncontrolled high
blood pressure, primary kidney diseases, or drug toxicities, which may result
in chronic medical problems. They may have complications of reduced kidney
function, such as hypertension, malnutrition, anaemia, bone disease, and
decreased quality of life. In addition, due to prolonged hemodialysis that may
compromise their immune system, they are vulnerable to infection, including UTIs.2

The underlying reasons
for the higher risk of UTI in patients with chronic kidney disease are thought
to be an altered host reaction and anatomic and functional disorders of the urinary
tract. The alteration in host protective functions is thought to be due to:1

·        
Loss of antibacterial properties of the
urine.

·        
Mild immunosuppression in uraemia.

·        
Inhibition of protective mucosa
production in the urothelium.

Evidence of a
correlation between chronic kidney disease and higher UTI risk is most solid
for autosomal dominant polycystic kidney disease (ADPKD) and chronic kidney disease
associated with stone disease.1

Patients with
type 2 diabetes mellitus are at increased risk of infections, with the urinary
tract being the most frequent infection site. Various impairments in the immune
system, in addition to poor metabolic control of diabetes, and incomplete
bladder emptying due to autonomic neuropathy may all contribute in the pathogenesis
of UTIs in diabetic patients. Factors that were found to enhance the risk for
UTI in diabetics include age, metabolic control, and long term complications,
primarily diabetic nephropathy and cystopathy.3

 

Diabetes is also
associated with worse outcomes of UTI, including longer hospitalizations and
increased mortality.3

 

The most common
pathogens isolated from urine of diabetic patients with UTI are Escherichia
coli, other Enterobacteriaceae such as Klebsiella spp., Proteus spp.,
Enterobacter spp., and Enterococci. Patients with diabetes are more prone to
have resistant pathogens as the cause of their UTI, including extended-spectrum
?-lactamase-positive Enterobacteriaceae, fluoroquinolone-resistant
uropathogens, carbapenem resistant Enterobacteriaceae, and vancomycin-resistant
Enterococci. This might be due to several factors, including multiple courses
of antibiotic therapy that are administered to these patients, frequently for
asymptomatic or only mildly symptomatic UTI, and increased incidence of
hospital-acquired

and
catheter-associated UTI, which are both associated with resistant pathogens.
Type 2 diabetes is also a risk factor for fungal UTI.3

 

Epidemiology

The frequency of
UTI in patients with chronic renal insufficiency is not known to be different from
that in the general population. On the one hand, the chronic disease that
causes the renal insufficiency could reduce the risk for UTI as a result of
reduction of risk factors such as sexual activity. Alternatively, the risk
might be increased by disease factors (e.g., papillary necrosis,
nephrolithiasis, neurogenic bladder) and the management of comorbidities with Foley
catheters and intravenous lines.4

 

Diabetes
mellitus (DM) has been identified as an independent risk factor for UTI.1 Type 2 diabetes is not
only a risk factor for community acquired UTI but also for health care
associated UTI, catheter associated UTI, and post renal transplant recurrent
UTI.3   Not only are
UTIs more prevalent in patients with DM, but the clinical manifestations and
impact of infections are also more intense. The factors that further increase
the risk of more severe UTI in patients with type 2 diabetes aged >45 yr
are: chronic antibiotic consumption, renal disease, urinary incontinence, and
age >60 yr.1

 

 

Clinical
Presentation

 

The characteristic
symptoms of UTI in the adult are primarily dysuria with irritating voiding
symptoms like urinary urgency, frequency, nocturia, painful voiding, bladder
discomfort or stranguria which greatly distress the patient. A sensation of
bladder fullness or lower abdominal discomfort is usually present.5

 

The spectrum of
UTI in diabetes patients ranges from asymptomatic bacteriuria (ASB) to lower
UTI (cystitis), pyelonephritis, and severe urosepsis. Serious complications of
UTI, such as emphysematous cystitis and pyelonephritis, renal abscesses and
renal papillary necrosis, are all encountered more frequently in type 2
diabetes than in the general population.3

 

The clinical
presentation and severity grading of UTIs are shown in Table 2.1