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Urinary tract infections Flashcards

1
Q

What is a urinary tract infection (UTI)?

A

A UTI is defined as the inflammatory response of the urothelium to bacterial invasion.

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2
Q

What are the common causes of UTIs?

A

UTIs are usually caused by reduced host defenses or micro-organism pathogenicity, or a combination of these factors.

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3
Q

How do UTIs typically develop?

A

UTIs usually develop as a result of the ascent of bowel organisms via the urethra, allowing bacteria to enter the urinary tract.

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4
Q

How can micro-organisms cause UTIs less commonly?

A

Less commonly, micro-organisms can result in UTI by hematogenous spread or direct transmission from adjacent infected organs.

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5
Q

What is the prevalence of UTIs in adults?

A

UTIs in adults are one of the most prevalent infectious diseases worldwide and impose a substantial financial burden on society.

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6
Q

What percentage of hospital-acquired infections are UTIs, and what is the main cause?

A

At least 20% of all hospital-acquired infections are UTIs, with the majority of cases (80%) being catheter-associated.

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7
Q

How can UTIs be classified?

A

UTIs can be broadly divided into uncomplicated, occurring in a patient with a structurally and functionally normal urinary tract, and complicated.

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8
Q

What is bacteriuria?

A

Bacteriuria refers to the presence of bacteria in the urine.

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9
Q

What is pyuria?

A

Pyuria indicates the presence of white blood cells in the urine.

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10
Q

What is sterile pyuria?

A

Sterile pyuria is the presence of white blood cells in the urine without the presence of bacteria.

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11
Q

What is asymptomatic bacteriuria?

A

Asymptomatic bacteriuria refers to the presence of bacteria in two consecutive urine cultures without any symptoms of upper or lower UTI.

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12
Q

What is an uncomplicated UTI?

A

An uncomplicated UTI occurs in patients with a structurally and functionally normal urinary tract without comorbidities that may lead to serious complications.

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13
Q

What is a complicated UTI?

A

A complicated UTI occurs in the presence of another condition, such as a structural or functional urinary tract abnormality or medical comorbidity, that increases the risk of persistent infection, recurrent infection, or treatment failure.

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14
Q

What is required for a UTI to be classified as complicated?

A

A positive urine culture along with a risk factor is required for a UTI to be classified as a complicated UTI.

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15
Q

What is recurrent UTI?

A

Recurrent UTI refers to an episode of UTI that occurs after documented successful resolution of a previous episode, with a frequency of at least twice in the previous 6 months or three times in the last 12 months.

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16
Q

What are the two classifications of recurrent UTI?

A

Recurrent UTI can be classified as either persistent or re-infection.

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17
Q

What does persistence indicate in recurrent UTI?

A

Persistence refers to recurrent UTI caused by the same organisms, indicating a focus of infection in the urinary tract, such as stones or fistulas.

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18
Q

What does re-infection indicate in recurrent UTI?

A

Re-infection refers to recurrent UTI caused by different organisms, indicating susceptibility to UTI, which can be influenced by genetic factors.

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19
Q

What are some factors associated with re-infection in recurrent UTIs?

A

Re-infection in recurrent UTIs is associated with poor hygiene, sexual intercourse, and post-menopause.

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20
Q

What percentage of female UTIs are due to re-infection?

A

Approximately 95% of female UTIs are due to re-infection.

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21
Q

What are uncomplicated UTIs?

A

Uncomplicated UTIs refer to acute, sporadic, or recurrent lower (uncomplicated cystitis) and/or upper (uncomplicated pyelonephritis) UTIs that are limited to non-pregnant women with no known relevant anatomical and functional abnormalities within the urinary tract or comorbidities.

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22
Q

What are complicated UTIs?

A

Complicated UTIs encompass all UTIs that are not defined as uncomplicated. In a narrower sense, they refer to UTIs in patients with an increased chance of a complicated course, such as men, pregnant women, patients with relevant anatomical or functional abnormalities of the urinary tract, indwelling urinary catheters, renal diseases, and/or other concomitant immunocompromising diseases like diabetes.

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23
Q

What are recurrent UTIs?

A

Recurrent UTIs are defined as the recurrences of uncomplicated and/or complicated UTIs, with a frequency of at least three UTIs per year or two UTIs in the last six months.

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24
Q

What is the epidemiology of UTI?

A

UTIs are common, accounting for 1-3% of all GP consultations and being the second most common cause of morbidity after respiratory infections. Up to 50% of females will experience at least one UTI in their lifetime, while the prevalence in infants is around 1-2%. UTIs occur in approximately 20% of men, with a low prevalence in younger men but significantly increasing with age, affecting 6-7% of those over 65. Additionally, about 20% of the elderly population has asymptomatic bacteriuria.

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25
Q

Why are women more susceptible to UTIs compared to men?

A

Women are more susceptible to UTIs due to factors such as having a shorter and straighter urethra, which facilitates bacterial access to the bladder.

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26
Q

What may predispose postmenopausal women to UTIs?

A

Postmenopausal women may be predisposed to UTIs due to oestrogen deficiency, which can lead to increased colonization with E. coli.

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27
Q

What is a common association of UTIs in men?

A

UTIs in men are often associated with urinary obstruction, such as bladder outlet obstruction due to prostate enlargement.

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28
Q

What is a common cause of UTIs in both men and women?

A

The use of indwelling catheters can cause UTIs in both men and women.

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29
Q

How does the anatomy of the male and female urethra differ?

A

The female urethra is shorter and straighter compared to the male urethra.

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30
Q

What is the aetiology of UTI?

A

The aetiology of UTI refers to the causative agents or microorganisms responsible for UTI.

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31
Q

What are the anatomical sites commonly affected by UTIs?

A

UTIs can occur in the urethra (urethritis), bladder (cystitis/lower UTI), prostate (bacterial prostatitis), kidneys and ureters (pyelonephritis/upper UTI), blood stream (urosepsis), and testes and epididymis (epididymo-orchitis).

32
Q

What are the risk factors for complicated UTIs?

A

Risk factors for complicated UTIs include conditions such as structural or functional abnormalities of the urinary tract, presence of indwelling catheters, renal diseases, immunocompromising diseases, and relevant comorbidities.

33
Q

What is acute cystitis?

A

Acute cystitis is defined as the infection and inflammation of the bladder urothelium. It is often associated with lower urinary tract symptoms (LUTS) including dysuria, frequency, urgency, suprapubic pain, and offensive urine.

34
Q

How common is UTI in females?

A

At least 50% of all females will experience one episode of UTI during their lifetime, making it one of the most common reasons for females to consult healthcare professionals.

35
Q

How does the prevalence of acute cystitis differ between men and women?

A

Acute cystitis is much more prevalent in women than only a small proportion of men aged 15-50.

36
Q

What are the indicative symptoms for the presence of UTI in acute cystitis?

A

If dysuria (painful urination) and frequency are both present, the probability of UTI is increased to over 90%, indicating the need for empirical treatment with antibiotics.

37
Q

Why is antibiotic therapy recommended for acute cystitis in women?

A

Antibiotic therapy is recommended because clinical success is significantly more likely in women treated with antibiotics compared to those who receive a placebo.

38
Q

How is acute pyelonephritis suspected?

A

Acute pyelonephritis is suspected in the presence of flank pain, nausea, vomiting, and pyrexia (fever).

39
Q

Why is it important to differentiate between acute, uncomplicated pyelonephritis and obstructive pyelonephritis?

A

It is essential to differentiate between these two conditions as acute pyelonephritis can result in significant urosepsis, and obstructive pyelonephritis may require different management approaches.

40
Q

What is the key evaluation method for identifying obstruction or renal stone disease in cases of acute pyelonephritis?

A

Imaging of the upper urinary tract is essential in evaluating for obstruction or renal stone disease in cases of acute pyelonephritis.

41
Q

What is the association between catheters and bacterial biofilm formation?

A

Catheters provide a focus for bacterial biofilm formation, which contributes to the colonization of two or more organisms in long-term indwelling catheters.

42
Q

How does the duration of catheterization affect the risk of infection?

A

The longer a catheter remains in place, the greater the likelihood of infection. Duration of catheterization is strongly associated with the risk of catheter-associated urinary tract infection (CAUTI).

43
Q

What is the prevalence of UTIs as hospital-acquired infections in the UK?

A

UTIs account for 23% of all hospital-acquired infections in the UK, making it a common healthcare-associated infection.

44
Q

What is the source of hospital-acquired bacteremia in a percentage of cases?

A

Catheter-associated UTI serves as the source for 8% of hospital-acquired bacteremia cases.

45
Q

What are some symptoms that may suggest UTI in patients with catheters?

A

Symptoms that may suggest UTI in patients with catheters include fever, flank or suprapubic discomfort, change in voiding patterns, nausea, vomiting, malaise, or confusion.

46
Q

When is antibiotic treatment recommended for UTI in catheterized patients?

A

Antibiotic treatment would be recommended for symptomatic UTI in catheterized patients. However, it would not be indicated in patients who are asymptomatic but have colonization of their catheters.

47
Q

What is the recommended approach regarding antibiotic prophylaxis prior to any instrumentation of the urinary tract?

A

Prior to any instrumentation of the urinary tract, patients would be given antibiotic prophylaxis to reduce the risk of infection.

48
Q

What is the typical setup for catheter-associated UTI?

A

A catheter is inserted with the balloon resting at the bladder neck, and a bag is attached to the catheter to drain urine.

49
Q

What is epididymo-orchitis?

A

Epididymo-orchitis refers to inflammation of the epididymis and/or testicle, causing pain and swelling. In young, sexually active men, the causative agent is usually Chlamydia trachomatis, so antimicrobials should be selected empirically based on this.

50
Q

What are the common uropathogens involved in epididymo-orchitis in older men with benign prostatic hyperplasia or micturition disturbances?

A

In older men with benign prostatic hyperplasia (BPH) or other micturition disturbances, the most common uropathogens involved include gram-negative organisms such as E. coli.

51
Q

What is the pathogenesis of UTIs?

A

The pathogenesis of UTIs involves the colonization of perineal flora, mainly gram-negative organisms, which can ascend retrogradely from the urethra. Bacteria adhere to the urothelium, release toxins, and stimulate urothelial cells to release chemokines, leading to an inflammatory response.

52
Q

How does the degree of virulence of uropathogens impact the severity of infection?

A

The degree of virulence of uropathogens varies, and the more virulent factors they express, the more severe the infection tends to be.

53
Q

How does compromised host natural defenses increase the risk of infection?

A

When the host’s natural defenses are compromised (e.g., due to obstruction or catheterization), fewer virulent factors need to be expressed by uropathogens to cause infection, which is particularly relevant in conditions like HIV infection.

54
Q

What are the stages involved in the pathogenesis of UTIs?

A

Contamination of the periurethral area with a uropathogen from the gut.
Colonization of the urethra and migration to the bladder.
Colonization and invasion of the bladder mediated by type 1 pili adhesin expressed by UPEC (E. coli).
Neutrophil infiltration.
Bacterial multiplication.
Biofilm formation.
Epithelial damage by bacterial toxins and proteases.
Ascension to the kidneys.
Colonization of the kidneys.
Host tissue damage by bacterial toxins.
Bacteremia.

55
Q

What are the clinical presentations of UTI?

A

Frequency
Urgency
Nocturia
Dysuria
Suprapubic or costovertebral angle pain or tenderness is usually indicative of cystitis or pyelonephritis, respectively.
Fever usually indicates a systemic response, possibly due to pyelonephritis.
Hypotension and altered mental status may indicate sepsis in the setting of urinary tract infection.

56
Q

What are the clinical presentations of pyelonephritis?

A

Clinical presentations of pyelonephritis include fever, rigors, loin pain, renal angle tenderness, and often lower UTI symptoms in addition. If pain radiates to the groin, it may indicate the presence of a stone. There is also a risk of bacteraemia.

57
Q

What is the role of the urothelium in UTIs?

A

The urothelium refers to the internal lining of the bladder wall. Bacteria can adhere to the urothelium and release toxins, contributing to UTIs.

58
Q

What is the significance of UPEC strains of E. coli in UTIs?

A

UPEC strains of E. coli can divert from their commensal status as intestinal flora and grow and persist in the urinary tract. They exhibit a diverse array of virulence factors and strategies, allowing them to infect and cause diseases in the urinary tract.

59
Q

What are some common symptoms associated with UTIs?

A

Common symptoms associated with UTIs include frequency, urgency, nocturia, and dysuria.

60
Q

What are some parameters measured in urine dipstick tests?

A

Urine dipstick tests can measure urinary pH, leukocyte esterase, nitrite, blood, and protein. These parameters provide information about the presence of certain organisms, inflammatory cells, and other urinary abnormalities.

61
Q

What does the presence of leukocytes in urine microscopy indicate?

A

The presence of more than 5 leukocytes per high-power field in urine microscopy denotes pyuria, which is indicative of inflammation or infection.

62
Q

What can cause sterile pyuria?

A

Sterile pyuria, which is pyuria with a negative midstream urine (MSU) culture, can occur with conditions such as bacterial infections (renal abscesses) or partially treated UTIs.

63
Q

What is the procedure for performing a urine culture from a midstream urine (MSU) sample?

A

In a urine culture from an MSU sample, 0.1ml of urine is delivered onto each half of a split-agar plate. One half of the plate contains blood agar for gram-positive organisms, while the other half contains eosin-methylene blue (EMB) agar for gram-negative organisms. The number of colonies is estimated after overnight incubation. This method is considered the gold standard for diagnosing UTIs.

64
Q

What is the colony count cutoff point for diagnosing a UTI?

A

A colony count of 105 is considered the cutoff point for diagnosing a UTI. However, it’s important to note that 50% of symptomatic women may have a lower colony count, and even 100 colonies may signal infection in a woman who has symptoms.

65
Q

What are some common gram-negative uropathogens?

A

Escherichia coli (gram-negative) accounts for approximately 65-75% of all UTIs. Other gram-negative uropathogens include Klebsiella, Proteus, and Pseudomonas species.

66
Q

What are some common gram-positive uropathogens?

A

Gram-positive organisms include Enterococcus faecalis and Staphylococcus.

67
Q

What imaging modalities can be used for renal imaging?

A

Renal imaging can be done using ultrasound or computed tomography (CT scan). Ultrasound may be obtained in patients who are systemically ill, especially those with a history of kidney stones, to rule out “pus under pressure” - an infection behind an obstruction that mimics an abscess.

68
Q

What is the recommended approach for managing uncomplicated cystitis in women?

A

In healthy, non-pregnant women with classic symptoms of acute UTI without evidence of pyelonephritis, empiric treatment or a urinary dipstick test is an appropriate approach. If the dipstick is negative or the patient has pelvic pain or abnormal vaginal discharge, a pelvic examination and urine culture are indicated.

69
Q

What is the recommended approach for managing uncomplicated cystitis in men?

A

A urine dipstick and culture are generally performed before therapy in men with uncomplicated cystitis.

70
Q

How can uncomplicated pyelonephritis be diagnosed?

A

Uncomplicated pyelonephritis is often diagnosed based on positive findings on the urinary dipstick, and a urine culture is sent for definitive diagnosis and to determine antimicrobial sensitivities.

71
Q

When is a complicated UTI suspected, and what is the recommended approach for management?

A

A complicated UTI is suspected in patients whose conditions relapse or do not improve with therapy. In these cases, a urine culture is always recommended. Complicated UTIs result from anatomical or functional abnormalities of the urinary tract or resistant infections. Catheter-associated UTI is considered a complicated UTI.

72
Q

When is screening for asymptomatic bacteriuria recommended?

A

Screening for asymptomatic bacteriuria is generally unnecessary unless the patient is pregnant (with a bacterial count of 10,000 CFU/mL or more to decrease the risk of pyelonephritis) or undergoing renal or urologic procedures.

73
Q

What factors should be considered when choosing antibiotic treatment for UTIs?

A

Factors to consider for antibiotic treatment include target organisms, route of administration, side effects, and resistance. It is important to check local guidelines for specific recommendations.

74
Q

How long is the typical duration of treatment for uncomplicated UTIs?

A

Uncomplicated UTIs usually require treatment for 5 days.

75
Q

What is the recommended empiric antibiotic therapy for UTI when the urine dipstick test is positive?

A

Empiric therapy is generally appropriate in such cases. Common options include:

Nitrofurantoin: 50mg, 4 times a day for 5-7 days.
Trimethoprim: 200mg, administered orally twice daily for 3 days.
A longer course of therapy (e.g., 7 days) may be appropriate in higher-risk patients, such as those with diabetes or older adults.
Men should be treated for 7 days. Nitrofurantoin should be given for at least 5 days, while fosfomycin can be given as a one-time single dose.

76
Q

What are some preventive measures for recurrent UTIs?

A

Some preventive measures for recurrent UTIs include correcting any underlying host causes (such as diabetes mellitus), antibiotic prophylaxis (temporary, between 6 months and 2 years), behavioral changes (e.g., high fluid intake, voiding after sex, double voiding), and non-antibiotic over-the-counter treatments such as cranberry, d-mannose, and hiprex. Oestrogen replacement therapy can be considered for postmenopausal women.

77
Q

How can catheter-acquired UTIs be prevented?

A

To prevent catheter-acquired UTIs, catheters should only be used for a valid reason, such as measurement of urine output in acutely unwell patients, management of acute retention or obstruction, or selected surgical procedures. Other preventive measures include aseptic insertion of the catheter, the use of a closed drainage system, and prompt removal of the catheter when it is no longer indicated.

NME (49 decks)

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