Urinary Tract Infection Flashcards
Urinary tract infections (UTIs) refer to an infection of any part of the urinary system from .. to the ..
Urinary tract infections (UTIs) refer to an infection of any part of the urinary system from kidney to the urethra.
UTIs are generally defined as the presence of characteristic symptoms (e.g. dysuria, frequency) and significant bacteriuria (presence of bacteria in urine). Significant bacteriuria is defined as > … colony forming units (CFU)/ml. In the absence of symptoms, this level of bacteriuria is termed asymptomatic bacteriuria.
UTIs are generally defined as the presence of characteristic symptoms (e.g. dysuria, frequency) and significant bacteriuria (presence of bacteria in urine). Significant bacteriuria is defined as > 10^5 colony forming units (CFU)/ml. In the absence of symptoms, this level of bacteriuria is termed asymptomatic bacteriuria.
UTIs can be further categorised depending on the location of infection (e.g. upper or lower) or the presence of co-morbidities (e.g. complicated or uncomplicated).
Upper UTI: infection of the kidney (pyelonephritis)
Lower UTI: infection of the bladder (cystitis) and urethra (urethritis)
Uncomplicated UTI: if occurring in healthy non-pregnant adult women
Complicated UTI: the presence of factors that increase the risk of treatment failure (e.g diabetes, structural abnormalities, catheter and other devices and all UTIs in men)
UTIs occurring in men are generally considered ‘…’ as many occur in children and the elderly in association with urological abnormalities, malignancy or immunosuppression.
UTIs occurring in men are generally considered ‘complicated’ as many occur in children and the elderly in association with urological abnormalities, malignancy or immunosuppression.
UTIs are caused by the organism… in 75-90% of cases.
UTIs are caused by the organism Escherichia coli in 75-90% of cases.
Gram negative bacillus
Escherichia coli (E. coli) is a … bacillus that is a facultative inhabitant of the large intestines. E. coli may cause a wide range of infections including, respiratory infections, intra-abdominal infections, enteric infections and urinary infections.
Uropathogenic strains of E. coli infect the urinary tract leading to a wide range of problems including urethritis, prostatitis, cystitis, pyelonephritis and urosepsis.
Escherichia coli (E. coli) is a gram-negative bacillus that is a facultative inhabitant of the large intestines. E. coli may cause a wide range of infections including, respiratory infections, intra-abdominal infections, enteric infections and urinary infections.
Uropathogenic strains of E. coli infect the urinary tract leading to a wide range of problems including urethritis, prostatitis, cystitis, pyelonephritis and urosepsis.
Other common microorganisms associated with UTIs include: (aside from E.coli)
Proteus mirabilis
Klebsiella pneumoniae
Staphylococcus saprophyticus
A growing number of UTIs are secondary to … (ESBL) producing E. coli.
A growing number of UTIs are secondary to extended-spectrum beta-lactamase (ESBL) producing E. coli.
ESBL
A growing number of UTIs are secondary to extended-spectrum beta-lactamase (ESBL) producing E. coli.
What are they highly resistant to?
These organisms are highly resistant to most beta-lactam antibiotics, which includes penicillins and cephalosporins. Beta-lactamases are enzymes which open the beta-lactam ring of beta-lactam antibiotics rendering them inactive.
ESBL infections are a growing cause of hospital-acquired infections associated with poor outcomes. The risk of developing ESBL infections is linked to the prior administration of antibiotics, the length of ITU stay and the presence of a urinary catheter, among others. Treatment often requires …
ESBL infections are a growing cause of hospital-acquired infections associated with poor outcomes. The risk of developing ESBL infections is linked to the prior administration of antibiotics, the length of ITU stay and the presence of a urinary catheter, among others. Treatment often requires potent, broad-spectrum antibiotics (e.g. Carbapenems).
Pathophysiology of UTI - overview
The normal urinary tract is a sterile environment.
The development of UTIs results from colonisation and ascending spread of microorganisms from the urethra into the bladder (lower) and kidney (upper), or by haematogenous spread via the blood. Many pathogens have adaptions that allow them to breach host defences.
Microorganism spread - UTI
In women, infections start with the colonisation of the vaginal introitus (entrance to the vaginal canal) and periurethral area. It then ascends the urethra to cause infection of the bladder. Infections are uncommon in men for a number of reasons. They have a longer urethra, prostatic secretions have some antimicrobial properties and their periurethral area is generally drier.
Why are UTIs less common in men?
Infections are uncommon in men for a number of reasons. They have a longer urethra, prostatic secretions have some antimicrobial properties and their periurethral area is generally drier.
UTIs may also develop from the haematogenous spread of microorganisms. However, common gram-negative bacilli (e.g. E. coli) are unlikely to cause infection by this route. Haematogenous spread is more often seen with uncommon urinary microorganisms such as …
UTIs may also develop from the haematogenous spread of microorganisms. However, common gram-negative bacilli (e.g. E. coli) are unlikely to cause infection by this route. Haematogenous spread is more often seen with uncommon urinary microorganisms such as Staphylococcus aureus, Candida albicans and Mycobacterium tuberculosis.
Host and pathogen - UTI
The ability of microorganisms to infect the urinary system is dependent on both the host and pathogen. Host factors such as intercurrent illness, immunosuppression (e.g. steroid use) or co-morbidities (e.g. diabetes) can increase the risk of developing a UTI.
Some pathogens are particularly well suited to infecting the urinary tract. For example, uropathogenic strains of E. coli contain fimbriae, these are hair-like protein polymers that project from the bacterial surface. They allow strong adherence to the urothelium. Fimbriae play a crucial role in the pathogenesis of UTIs and have been shown to increase bacterial survival.
Risk factors for UTI
UTIs are extremely common especially among young, sexually active females.
Risk factors for the development of UTIs include:
Recent sexual intercourse Diabetes History of UTIs Spermicide use Catheters
… are one of the major risk factors for developing a UTI in secondary care.
Urinary catheters are one of the major risk factors for developing a UTI in secondary care. UTIs associated with catheters are a leading cause of hospital-associated bacteraemia.
Typical clinical features of UTIs include (2)
Typical clinical features of UTIs include dysuria (often described as burning) and increased frequency.
Symptoms in UTI
Dysuria Frequency Urgency Incontinence Suprapubic pain Haematuria N&V
Dysuria is commonly described, women who suffer with recurrent UTIs will often identify the symptoms early. Clinicians should be alert for signs of … which include kidney pain, myalgia, fevers, rigors and nausea/vomiting.
Dysuria is commonly described, women who suffer with recurrent UTIs will often identify the symptoms early. Clinicians should be alert for signs of pyelonephritis which include kidney pain, myalgia, fevers, rigors and nausea/vomiting.
Signs of UTI
Fever Rigors Flank pain Confusion Costovertebral angle tenderness
Signs and symptoms of…
UTI
Urosepsis - define
Urosepsis refers to a sepsis that originates from a urinary infection. Sepsis can be thought of as a dysregulated host response to infection leading to life-threatening organ dysfunction. Features include haemodynamic instability, tachypnea, changes to mental status, reduced urine ouput and pyrexia.
There are a number of scoring systems that can be used to assess risk and prognosis, each has their own limitations. An example is qSOFA (quick Sepsis Related Failure Assessment) that aims to identify patients at increased risk of poor outcomes outside the ITU environment. It consists of three components:
Mental status (score 1 if altered mental status) Respiratory rate (score 1 if ≥ 22) Systolic BP (score 1 if ≤ 100)