URINARY TRACT INFECTION (UTI)

Objectives

General Goal: To know the major cause(s) of these diseases, how they are transmitted, and the major manifestations of each disease.

Specific Objectives: The student should be able to:

1. To know the common cause(s) of these disease.2. To know the common means of transmission.3. To know the major manifestations of this

infection.4. To know how you diagnose, treat and prevent

this infection.

UTI

• 2nd in OPD patient visits after RTI• Leading cause of hospital acquired infections

• Protective Mechanisms in Urinary Tract

• Fast urine flow• Anatomy – urethral valves prevent backflow of

urine• Acidic urine • Inflammatory process – phagocytosis of

pathogens

UTI : Predisposing Factors

• Urinary stasis (obstruction to flow)o Too busy to empty bladder (occupational)o Urinary stoneso Bladder tumorso Prostate enlargement o Pregnancyo After anaesthezia & major surgery

(reflex ability to void urine is inhibited)

• Urinary catheterization : recurrent UTI• Anomalies of urinary tract• Constipation in children and elderly• Poor perineal hygiene in elderly• Eight times more common in females

(anatomy)

UTI : OrganismsA. Cystitis & PyelonephritisCommon Pathogens• Escherichia coli (commonest cause)• Klebsiella pneumoniae• Proteus species• Pseudomonas aeruginosa• Enterobacter species• Enterococcus fecalis• Staphylococcus saprophyticus (in young women)• Proteus : Associated with renal stones

Uncommon Pathogens• Mycobacterium tuberculosis• Leptospira interrogans• Schistosoma species• Candida albicans : in diabetics and

immunocompromised

Usually Hospital acquired

B. Urethritis• Chlamydia trachomatis• Ureaplasma urealyticum• Neisseria gonorrhoeae• Trichomonas vaginalis

UTI : Organisms

• Ascending infection : The most common

• Blood-borneo M. tuberculosiso Leptospira interroganso Salmonella

UTI : Source of organisms

UTI : Clinical Features

Cystitis• Dysuria

o Dysuria without vaginal discharge have a UTI

o Vaginal infection and irritation can cause dysuria

• Urinary frequency and urgency • Supra-pubic pain and tenderness• Haematuria

Urethritis• Discomfort during voiding• Burning micturation • No supra-pubic discomfort

Pyelonephritis• Flank pain & fever• Nausea and vomiting

UTI : Clinical Features

Hemorrhagic cystitis (haematuria)

Visible blood in the urine • Bacterial infection • Adenovirus types 1-47 infection• Bladder stones• Schistosomiasis • After radiation therapy • Cancer chemotherapy• Immunosuppressive medication

UTI : Clinical Features

Complications

• Bacteremia

• Chronic pyelonephritis

• Renal abscess

• Death

UTI : Lab Diagnosis

Collection (sterile container) • Bacterial Infection : first morning midstream

urine• Schistosomiasis : last 5-10 ml of urine• Male urethritis : first 5-10 ml of urine

(urethral swab is the correct specimen) Instructions to patient for aseptic collection

TransportWithout delay: Otherwise at room temperature

Bacteria will multiply : false bacterial count WBCs, RBCs will start to lyse Glucose, protein will alter

UTI : Lab diagnosis

Pyuria without bacteriuria• Patient on antimicrobial treatment• Renal stones• Renal tuberculosis• Gonococcal urethritis• Chlamydia trachomatis infection• Leptospirosis• Scistosomiasis

Bacteriuria without pyuria• Urine contamination • Bacterial endocarditis• Diabetes mellitus• Enteric fever

Recurrent Infection Vs Re-infection

Recurrent infection • Occurs within 2 weeks of completing

antimicrobial therapy • Caused by the original pathogen• Causes scarring and shrinkage of kidneys :

An important cause of kidney failureRe-infection • Occurs after 2 weeks of completing antimicrobial

therapy

• May be caused by the same or a different organism

Differentiation between UTI and bacteriuria

• Pyuria alone = inflammation • Bacteriuria without pyuria = colonization • Pyuria + bacteriuria + nitrites = infection

UTI : Lab diagnosis

Physical appearance• Cloudy

o Bacterial UTI

• Red & cloudy o Bacterial UTI & Schistosomiasis

• Yellow-brown o Acute viral hepatitis & o obstructive jaundice

• Milky white o Bancroftian filariasis

UTI : Lab Diagnosis

MicroscopyExamined as wet preparation to detect:• Significant pyuria : WBCs >10 cells/ul of

urine• RBCs• Epithelial cells• Yeast cells• Trichomonas vaginalis trophozoites• Schistosoma haematobium eggs• Crystals • Casts

UTI : Lab Diagnosis

Culture• Not more than 24 h• Significant bacteriuria• <104 CFU (colony forming unit) bacteria/ml and/or

More than one bacterial types• >/=105 CFU bacteria/ml of urine : UTI

Dipsticks• Nitrite test : for enterobactericeae• Leucocyte-esterase test : for WBCs• Protein

UTI : Lab Diagnosis

contamination

• Cystitis : easily treated in few days• Pyelonephritis : Prolonged

treatment• Complicated UTI : Prolonged

treatment• Is accompanied by an underlying risk

factors :o Prostatic enlargemento Urologic dysfunctiono Resistant pathogens

• Recurrent UTI : Prolonged + Combination therapy

UTI : Treatment

UTI : TreatmentBeta-lactams • Amoxicillin• Amoxicillin/clavulanate• Cephalexin, cefixime

Quinolones• Nalidixic acid• Norfloxacin

Nitrofurantoin • Spares disruption of normal vaginal flora and • Consistent efficacy against E coli and Staphylococcus

saprophyticus • Should be avoided after the 36th week of gestation

due to risk for hemolysis if the fetus is G6PD-deficient

Case study

A 77 year-old surgical patient, who had been discharged to a long-term care facility 6 months earlier, developed

dementia with a concomitant elevated temperature (39.50C), and mildly elevated WBC (12,000 WBC/l).

Peripheral blood culture and clean catch urine specimens were collected. The urine specimen was sent on ice to

laboratory. A screening urine analysis indicated a moderate level of yeast

and rods and yielded a positive result on leukocyte esterase test. A Gram stain performed, revealed several gram –

negative rods of similar morph type and a few WBC. Culture performed at 24 h showed 100,000 CFU/ml mixed colonies

of E. coli and Klebsiella pneumonia, fewer than 10,000 of lactobacilli, viridians streptococci, and yeast. Blood culture

result were negative

Questions1. How would the urine culture be worked up and reported?2. Where do these organisms originate?3. What is the difference between single episode UTI and

recurrent UTI?4. What is the value of screening urinalysis an Gram stain

procedures?

5. What is the optimum incubation period for routine urine culture?

6. What may occur if routine urine culture are incubated longer than 24 hours?

7. What is the significance of yeast quantitation in a urine specimens?

8. What is the definition of contaminated urine?9. Should susceptibility test be performed for all organisms

isolated from urine?