Urinary Tract Infection (UTI) Past Paper - Oct 2022

Objective of study: At the end of the lesson, you should be able to: URINARY TRACT Describe the diseases caused by urinary tract pathogens...

Objective of study: At the end of the lesson, you should be able to: URINARY TRACT Describe the diseases caused by urinary tract pathogens List the pathogens involved in urinary tract infection. INFECTION List the clinical specimens involved in the diagnosis of urinary tract infection. Dr Emida Mohamed Explain the workup involved in the diagnosis of urinary tract infection. Oct 2022 Urinary Tract Infection (UTI) Epidemiology of UTI Urinary tract infections (UTI) are Among the most common infection infections or caused by bacteria in any part of Prevalence is age & sex dependent urinary system. Age: during first year of life UTI is rare in male & female Bacteria often enter the urinary increases with age for both male & female (lower in male but increase for tract through urethra from the male above 50 yrs) outside of the body. Increases in female during pregnancy due to anatomical and hormonal changes-lead to serious infection to mother & foetus bacteria enter Common complications of diabetes, renal disease & renal transplant Anatomy of the urinary tract Normal flora of the urinary tract Consists of kidneys, ureter, bladder and urethra The urethra has resident microflora that resides in Characterized as : the epithelium upper UTI; kidney & ureter All areas above the urethra Lower UTI; bladder & urethra in a healthy person are Female urethra is importance in considered sterile pathogenesis: Urine is supposed to be relatively shorter than in sterile male_bacteria can reach bladder more easily nearer to the warm & moist perirectal region Etiologic agents Route of infection Community acquired infections are infections that are: Two major routes of infection: contracted outside of a hospital or diagnosed within 48 hours of by hematogenous (descending) route admission without any previous as a result of bacteraemia health care encounter. common pathogens: Candida albicans, Mycobacterium In nosocomial acquired infection tuberculosis, Staphylococcus aureus, Salmonella spp & Leptospira spp. insertion of a foreign object into the urinary tract increases the risk by ascending route through urethra of UTI: catheter Most common route for female & nosocomial UTI Host defence In most cases host defence mechanisms are able to eliminate the pathogen via: normal urination antimicrobial urine anatomical structure of urinary tract mucosal surface barrier 3 defense mechanism first line. Valve-like mechanism at the junction of ureter and bladder prevents reflux of urine from bladder to upper urinary tract activation of host immune response Bladder mucosal surface has antibacterial properties thus confining infection in the superficial mucosal layer, rarely involving deep layers of bladder Pathogen virulence factors Although many microorganism can cause UTI, only a limited number can Activation of host cause significant UTI. immune response Have virulence factors to enhance their ability to invade and colonize the Bacterial contact with urothelial cells will initiate urinary tract such as: immune response via a Surface structures to increase adherence to cells: pili and fimbriae variety of signalling Type 1 fimbriae that binds to uroepithelial cells pathways; production of Type P fimbriae that recognize kidney glycosphingolipids cytokines, defensins and Production of hemolysin opsonins. Alpha & beta hemolysin that lyse host RBCs Production of Capsules Protein that acts as proteolytic toxin or urease to hydrolyse urea Motile:can ascend to upper urinary tract against urine flow Uropathogenic E.coli Pathogens Siderophores that gather iron from host Uncomplicated infection: in healthy person* Complicated infection: in patients with risk factors# (underlying disease; diabetes, kidney stone, structural/ functional abnormality of urinary tract, indwelling catheter) * Respond readily to antibiotic # difficult to treat & with greater morbidity (kidney damage & bacteraemia) & mortality (death) Diseases due to UTI Clinical symptoms ↑ E paling teruk sebab effect kidney  Urethritis Cystitis bladder Infection of the urethra Common infection Infection of the bladder Cause of infection Common infection in women (shorter typically sexually transmitted or urethral length) pathogens from skin around urethra opening Caused by: Categorized as sexually transmitted. E.coli* Symptoms: Symptoms: Gonococcal urethritis :Neisseria gonorrhoeae Klebsiella Burning on urination Dysuria (difficulty to urinate) Frequent urination with only small Non-gonococcal urethritis*: Chlamydia Frequent urination trachomatis, Trichomonas vaginalis, Candida Proteus volume Urgent need to urinate Urgent need to urinate * Caused by dehydration, catheter, chemical irritants Blood in urine Staphylococcus saprophyticus Blood in urine Cloudy urine Bloody discharge from penis Bad odour *most common makin ternk. Yellowish discharge from urethra Tenderness & pain in area around V Lower abdominal pain bladder Pyelonephritis Inflammation of kidney parenchyma, calice & renal Prostatitis pelvic Complication of : an ascending UTI which spreads from bladder to kidney (most common) or Inflammation of the prostate gland from hematogenous spread (patients with urethral Use of catheter or from hematogenous obstruction or immunocompromised) spread Caused by gram negative bacteria (common): E.coli Causative Agent Proteus E. coli ( 50% - 90%) Symptoms: Klebsiella Pseudomonas Burning on urination Enterobacter Klebsiella Frequent urination Caused by gram positif bacteria: Enterobacter Urgent need to urinate Staph. saprophyticus Fever Staph. epidermidis Proteus Lower back pain 40% patients with acute pyelonephritis have Serratia Vomiting bacteraemia Less common: Salmonella, Candida & Diarrhoea Cryptococcus Chills Prevention of UTI Laboratory diagnosis Specimen collection Clean catch mid stream urine Least invasive method Main consideration: prevent contamination by normal vaginal & urethral flora Must be done carefully especially for female Type of specimen : Good patient education is essential to Urine ensure compliance proper specimen collection via: Suprapubic Printed guideline in many language Midstream clean catch bladder infographic method aspiration Indwelling Straight catheter a catheter  Indwelling catheter Suprapubic bladder aspiration Catheter drains urine from bladder into a bag outside Common reasons to have an indwelling catheter are: Urine is drawn directly into a syringe from urinary incontinence (leakage) the bladder to ensure a contamination-free urinary retention (not being able to urinate) specimen Lis surgery that made this catheter necessary For paediatric; premature infant, infant, Catheter port or wall of tubing should be cleaned with 70% ethanol vigorously prior to collection small children or pregnant women & adults Use needle and syringe to aseptically collect 20 mL Bladder must be full freshly voided urine through catheter port Do not collect urine from urine collection bag. Straight catheter Paediatric sample collection also called an intermittent catheter a soft, thin tube inserted several times a day just long enough to drain C urine from bladder Place sterile urine container under catheter to catch 4 mL mid stream urine Catheter can be removed  Specimen transport Screening procedure ⑯ Urine is an excellent supportive medium for growth of Not all urine samples received contain etiologic agents bacteria Procedure to identify quickly :screening but not for samples from Must be immediately refrigerated or preserved suprapubic aspiration & catheter Can be left up to 2 hours at room temperature Based oncolour andclarity Bacterial count in refrigerated 40C remains constant for 24 hours - Perform macroscopic analysis of urine Urine transport medium containing boric acid / glycerol / sodium format can preserve bacteria without Perform urinalysis for screening using reagent strip refrigeration for 24 hours Reportbacteria, whitecells, red cells, yeast cells, casts, Must be used with a minimum of 3 ml urine Perform microscopic analysis of urine epithelial cells, crystals ⑳ Urine transport tube I Perform gram stain if bacteria detected : S Urine culture Read colony morphology on culture plate Urine should be mixed thoroughly before plating Using a calibrated loop or sterile pipette tips to Report the number of bacteria counts and transfer a constant amount of urine sample colony* preference Culture urine on Blood agar and MacConkey or Perform gram stain Cysteine Lactose Electrolyte Deficient (CLED)* * Advantage for growth support of most potential Perform biochemical testing uropathogens including Gram positive cocci (staphylococci, streptococci & enterococci). Perform Antimicrobial Susceptibility Testing *Semi-quantitative urine culture (AST)  Interpretation of urine culture Major problem in interpretation: urine culture may be contaminated with normal flora Determining whether the colony count represent true infection or only contamination is of importance ine Propose the use of cut off in colony count based on clinical presentation Differ according to lab Additional notes Thank you