UTIs

Question 1

Routes of Infection UTIs

Answer 1

Ascending: Bacterial pathogens enter the urinary tract from the bowel reservoir via ascent through the urethra into the bladder

Haematogenous: Infection of the urinary tract, especially the kidneys, by organisms originating in the bloodstream

Lymphatic: Direct extention of bacteria from the adjacent organs via lymphatics. Usually rare, but can occur in unusual circumstances, such as severe bowel infection/abscesses

Question 2

Uncomplicated UTI

Answer 2

– Infection in a healthy patient with a structurally and functionally normal urinary tract

– Majority of patients are women with cystitis, or those with acute pyelonephritis

– Organisms are usually susceptible to antimicrobial therapies

Question 3

Recurrent UTIs

Answer 3

Infection that occurs after documented successful resolution of an infection

1. Bacterial persistence(relapse):UTI caused by the same bacteria that reemerge from a focus within the urinary tract (from an infectious stone [calculus/calculi], or prostate infection). Infections usually occur at close intervals
2. Reinfection: Recurrent infections caused by new (different) bacteria and occur at varying and sometimes long intervals

Question 4

Complicated UTIs

Answer 4

– Associated with factors that increase the chances of acquiring bacteria and decrease the efficacy of antimicrobial therapies. In this case, the urinary tract is functionally and structurally abnormal

– Majority of cases are men

– Organisms are usually resistant to one or more antimicrobial therapies

Question 5

Risk factors for UTIs

Answer 5

1. Reduced Urine Flow

• Outflow obstruction, prostatic hyperplasia, prostatic carcinoma, urethral stricture, foreign body (calculus)
• Neurogenic bladder
• Inadequate fluid uptake (dehydration)

2. Promote Colonisation

• Sexual activity – increased inoculation Spermicide – increased binding
• Estrogen depletion – increased binding
• Antimicrobial agents – decreased indigenous flora

Facilitate Ascent

• *Catheterisation
• Urinary incontinence
• Faecal incontinence
• Residual urine with ischemia of bladder wall

Question 6

Factors suggesting complicated UTIs

Answer 6

• Functional or anatomic abnormality of urinary tract Male gender
• *Pregnancy
• Elderly patient
• *Diabetes
• Immunosuppression
• Childhood UTI
• Recent antimicrobial agent use
• *Indwelling urinary catheter
• Urinary tract instrumentation
• Hospital-acquired infection
• Symptoms for more than 7 days at presentation

Question 7

Types of lower urinary tract infections

Answer 7

• Urethritis
• Cystitis
• Prostatitis

Question 8

Types of upper urinary tract infections

Answer 8

• Ureteritis
• Pyelonephritis

Question 9

Cystitis

Answer 9

Superficial infection of the bladder mucosa

Question 10

Cystitis symptoms

Answer 10

• Dysuria
• Frequency and/or urgency » Suprapubic tenderness
• Haematuria
• Nocturia
• Cloudy,foul-smellingurine
• Fever and chills are not usually present

Question 11

Cystitis diagnosis

Answer 11

Microscopic urinalysis, which usually indicates pyuria, bacteriuria, and haematuria

*Urine culture remains definitive test; presence of ≥ 108 bacteria/L usually indicates infection

Question 12

Cystitis ddx

Answer 12

• Volvovaginitis
• Urethritis

Question 13

Volvovaginitis

Answer 13

• Dysuria subacute in onset;
• Vaginal discharge or odor; fluid shows presence of inflammatory cells
• Frequency, urgency, haematuria, and suprapubic pain are usually not present
• History reveals new or multiple sexual partners
• Common microbial causes include, Chlamydia, Gonorrhoeae, Trichomoniasis, and yeast infections

Question 14

Urethritis

Answer 14

• Dysuria is subacute in onset and is associated with urethral discharge with inflammatory cells
• History reveals new or multiple sexual partners
• Common microbial causes of urethritis include, Neisseria gonorrhoeae, Chlamydia, Herpes Simplex Virus (HSV), and Trichomoniasis
• Less pronounced frequency/urgency than that associated with acute cystitis

Question 15

Pyelonephritis

Answer 15

Inflammation of the kidney and renal pelvis

Question 16

Pyelonephritis symptoms

Answer 16

• Abrupt onset of chills
• Accompanied by dysuria frequency, and urgency
• Fever (≥ 38oC)
• Nausea and vomiting
• Unilateral/bilateral flank (costovertebral angle) pain

Question 17

Laboratory diagnosis of pyelonephritis and further investigations

Answer 17

Urinalysis reveals

• Bacteriuria
• Numerous WBCs often in ‘casts’

Blood cultures should be performed in both mena nd women with systemic toxicity (i.e. in the clinical setting of SIRS). If blood cultures remain positive in the presence of persistent high fever and toxicity, urological evaluation is needed to exclude urinary obstruction/intrarenal abscess (consider: ultrasound, MRI, CT scan)

Question 18

Prostatitis clinical syndromes

Answer 18

1. Acute bacterial prostatitis
2. Chronic bacterial prostatitis
3. Represents a complicated UTI

Question 19

Symptoms of acute prostatitis

Answer 19

• Perineal pain
• Dysuria, frequency, urgency
• Fever
• Prostatic tenderness

Question 20

Laboratory diagnosis prostatitis and further investigations.

Answer 20

Urine analysis reveals pyuria and bacteriuria.

Exclude complications

• Bacteraemia
• Abscess formation (ultrasound)

Question 21

Specimen collection

Answer 21

• Female patients should be encouraged to clean the urethral opening prior to collection of specimen.
• Multiple specifimens may be required for an accurate diagnosis to be made
• The doubling time of bacteria at RT can be <60 minutes
  
  • Specimens must be delivered to the lab promptly
  • If unable to deliver immediately, specimens should be refrigerated

Question 22

Causative organisms of UTIs in community.

Answer 22

1. E. coli (80%)
2. Coagulase negative staph (10%)
3. Other gram positives

Question 23

Caustive organisms hospital acquired UTIs

Answer 23

1. E. coli (40%)
2. Other gram negatives (25%): e.g. Klebsiella, Enterobacter
3. Othe gram positives (16%)

Question 24

E. coli UTIs

Answer 24

• Normal flora in the gut
• 80% of community acquired UTIs
• 40% of nosocomial UTIs
• Gut –> peruneum –> vagina –> urethra

Treatment: generally sensitive to antimicrobials

Question 25

*Proteus mirabilis *

Answer 25

* 5% of community acquired UTIs * 11% of nosocomial UTIs * Normal flora in the gut * Strong urease producer (causes renal calculi) Urea --\> Amonia Treatment: generally sensitive to antimicrobials

Question 26

Gram negative rods

Answer 26

* 3% of community acquired UTIs * 25% of nosocomial UTIs Normal flora in gut. Includes bacteria: – Klebsiella species – Serratia marcescens – Enterobacter species Treatment: some are highly resistant to antimicrobials (esp. Nosocomial strains)

Question 27

*Pseudomonas aeruginosa*

Answer 27

**Gram negative rod. ** ## Footnote Can be normal flora in the gut, especially when patient has been on antimicrobial therapy. Sometimes acquired from hospital environment (especially when catheterised - forms biofilms on catheters). Treatment: often highly resistant to antimicrobials

Question 28

Coagulase-negative Staphylococci

Answer 28

* 10% of community acquired UTIs. * 3% of nosocomial UTIs * Thsi includes *S. saprophyticus* * Normal skin flora and urethral flora * Forms biofilms on plastic (including urinary catheters) * Treatment: defer to laboratory results

Question 29

*Staphylococcus saprophyticus *

Answer 29

* 5-10% of community acquired UTI * Belongs to the Coagulase negative Staphylococcus group * Sensitive to the laboratory antimicrobial agent 'novobiocin' Causes **honeymoon cystitis** Treatment: generall sensitive to amoxycillin

Question 30

*Staphylococcus aureus *

Answer 30

* Coagulase positive Staphylococcus * Rare cause of UTI * When causing UTI, infection generally occurs via the haematogenous route * Exclude septicaemia/bacteraemia * Local infection in setting of indwelling catheter Treatment: defer to laboratory sensitivity report Watch out for: methicillin resistant staphylococcusaureus (MRSA)

Question 31

*Enterococcus species*

Answer 31

More common in hospital than community * *E. faecalis* * *E. faecium* *​*Normal flora in the gut. Treatment: amoxycillin (variable sensitivity), nitrofurantoin or vancomycin. Intrinsically resistant to: – All cephalosporins, gentamicin, trimethoprim and cotrimoxazole Watch out for: vanvomycin resistant enterococci (VRE)

Question 32

Steptococcus agalactiae

Answer 32

* 2% of community and nosocomial UTIs * *Group B streptococcus* * Normal flora of the gut (+/- vagina) * Important neonatal pathogen - **always treat in pregnant women** (even if reported as part of mixed growth) Treatment: generally sensitive to antimicrobials used in treatment of UTI - only use classes of antimicrobial allowable if pregnant.

Question 33

Candida spp

Answer 33

* 5% of nosocomial UTIs * Candida is a yeast (fungi) * Exclude local infection - volvovaginitis * Candida may occur in association with infection of the upper urinary tract and/or systemic candidiasis * Colonises catheter: esp. important in immunosuppressed/intensive therapy patients Treatment: Fluconazole

Question 34

Laboratory diagnosis methods for UTIs

Answer 34

1. Microscopic examination of urine 2. Rapid indirect (Dipstick) methods

Question 35

UTI microscopic examination of the urine findings

Answer 35

Urine might show presence of: – **Pyuria**: defined as ≥ 10 x 106 leukocytes / L – **Haematuria**: erythrocytes ≥ 12 x 106 / L NOTE: Presence of RBC might also be indicative of other disorders like tumours, vasculitis, and glomerulonephritis – **Bacteriuria** : bacteria present at ≥ 108 / L\*

Question 36

When may microscopic examination of the urine yield false results?

Answer 36

**Contamination of sample**: squamous epithelial cells present at ≥ 10 x 106 / L **Women exhibiting urethral syndrome: ** * Signs of lower tract infection (dysureia, frequency etc) * Usually \<108 bacteria/L \<108 bacteria/L may also indicate... * previous antibiotic therapy * slower growing (fastidious) organisms

Question 37

Rapid indirect (Dipstick) findings with UTI

Answer 37

Presence of urine nitrate: * Bacteria convert nitrate present in the medium to nitrite * Puresence of pyuria detected by leukocyte esterase test NOTE: A negative leukocyte test plus negative nitrite test are strongly predictive of the absence of UTI