Urinary tract Infections:

-At least 20% of all women experience an incident of

Urinary tract infection (UTI) by the age of 30 years, and

over 50% have one or more lifetime UTIs.

One in ten women experience frequent recurrent

infections for at least some period.

-An estimated 3 million office visits for this infection take

place each year in the United States.

N

-Nosocomial UTI accounts for about 40% of all infections acquired in acute care facilities.

-From 25 to 50% of nursing home patients have bacteriuria at any time.

Urinary tract infection UTI is more common in Women due to:1-Anatomy of female Urinary tracts: Short urethra, and proximity of the urethral opening to the anus.2-Lack of antibacterial prostatic secretions.

3- Bacterial invasion by sexual intercourse.

N

-UTI could be established in different sexes due to the following risk factors:1-Poor personal hygiene.2-Insertion of contaminated Catheter.

-Physical and chemical barriers that protect human urinary tracts from infection: 1-The frequent flushing action of urine.

2- Urine acidity ( pH from 4.5 to 8 ).

3- The prostatic secretions (lysozyme and IgA).

Definitions: UTI could occur at any site of urinary tract; including Kidney, bladder, and in men, the prostate.Upper UTI: Kidney infection.

Lower UTI: 1-Urinary bladder infection. 2-Urethra infections are classified as sexually transmitted diseases. Pyelonephritis: (Pyelum: Renal pelvis, Nephro: kidney) :

is an ascending urinary tract infection that has reached

the pelvis of the kidney.

N

Pyelonephritis:1-Acute non-obstructive pyelonephritis: Acute inflammation of renal pelvis and medullary tissue due to bacterial invasion.

2-Complicated pyelonephritis: -Underlying structural or functional abnormalities of Kidney. -Could be associated with obstruction of renal pelvis. -Tissue dysfunction or Renal abscess.

N

-Urinary tract Reinfection:

Recurrent infection when a previously isolated organism

is reintroduced into the urinary tract from the colonizing

gut or genital flora.

-Relapse:

Recurrent infection with bacteria that persist within the

urinary tract due to indwelling urologic devices; such as

urethral catheter or nephrostomy tube.

n

-Biofilm: is a layer of bacteria, their extracellular

substances, and urine components (protein, calcium,

Mg+2) contaminating drainage bag grow along the

exterior or internal catheter surface.

-Biofilm is strongly associated with establishment of

complicated pyelonephritis.

Pathogenesis: Source of infecting organisms:1-The colonizing flora from the periurethral area or, in woman, the vagina.

2-Bacteria originate from the normal gut flora.

3-Contaminated urologic devices.

Pathogenesis:A-Lower urinary tract infection (Uropathogenic Escherichia coli).

N

B-Adherence of E.coli to mannosylated glycoprotein that line the bladder mucosa due to mannose sensitive fimbria FimH.

C-Ascend to the kidney due to: 1-Reflux of infected urine up the ureter. -Short intravesical ureter. -Incompetent ureteral sphincters.

2-PMN cell influx up the ureter.

D- Bacterial entry through the papillae into the renal parenchyma.

N

E-Adhesion of microbes to interstitial tissue surrounding

the tubules and renal cells in kidney medulla due to

P Fimbria (K polysaccharide) – glycosphingolipid

disaccharide receptor interaction.

N

F-Damage of interstitial tissue due to:

1-Cytokines production, cellular infiltration;

inflammation (Toxic O2 radicals, and lysozymes ).

2-Activation of clotting factors; ischemia.

3-Microbial virulence: Hemolysin, and urease activity.

G-Tubulointerstitial nephritis.

Pathogenesis:N

Types of Tubulointerstitial Nephritis:

1-Acute TIN: - Inflammatory infiltrate and edema affecting the renal interstitial tissue that often develops during days to months. - Over 95% of cases result from infection or an allergic drug reaction.

- Renal abscess could be illustrated microscopically in some cases (Rare).

- Renal abscess (uncommon) mainly caused by bacteremic spread of infection from other body site.

N

-Interstitial renal abscesses : Necrosis contains neutrophils, and central germ colonies (hematoxylinophils). -Tubules are damaged and may contain neutrophil casts.-In the early stages, the glomerulus and vessels are normal.

Causes of Pyelonephritis and TIN:

1- Escherichia coli. The most common cause of UTI ( 85-90%). 2- Staphylococcus saprophyticus. It is considered as a second causative agent of UTI (5-20%).

3- Other genera of Enterobacteriaceae : Klebsiella, Enterobacter, Proteus, and Serratia.

4- Pseudomonas aeruginosa ( Hospital-acquired infection).

5- Enterococcus faecalis ( Hospital-acquired infection).

n

2-Chronic TIN: -Gradual interstitial infiltration and fibrosis, tubular atrophy and dysfunction, and a gradual deterioration of renal tissue, usually over years.-Glomerular involvement is much more common in chronic nephritis than acute type.

-Causes: immunologically mediated disorders, infections, and drug interaction.

Glomerulonephritis : GN:

GN: is the inflammation of the Glomeruli of the nephron. Types: 1-Infective: Source of infection: Hematogenous dissemination. Pathologic feature: One or more renal cortical abscesses. Pathogenesis: Insoluble antigen trapped in the glomerulus Antibodies attack the Inflammatory structural components destruction of the of the kidney and antigen. Glomeruli.

N

2-Non-Infective GN: Soluble antigen in blood stream; Antibodies react with soluble antigen; Serum sickness disease; Precipitation of complexes in glomeruli; inflammatory destruction.

Types of soluble antigen: 1- Exogenous: A-Drugs, toxoid, or serum. B-Infectious agent antigen: - Post-Streptococcal glomerulonephritis: Anti-Streptolysin-O complexes.

n

Other infections: Bacterial: Staphylococci, Streptococcus pneumoniae, Klebsella, Yersinia enterocolitica, Treponema, Salmonella. Parasites: Malaria, Schistosoma, and Toxoplasma. Viral : Hepatitis, and E.B.V. Fungal: Candidiasis.

2- Endogenous: Self antigen.

Differential Diagnosis:

Urine analysis:1- Physical properties: -Appearance: turbidity or milky: pus in urine -Color: 1-white color: Pus in urine: Pyuria :infection 2-Red color: RBCs in urine: (Hematuria): kidney stones, infections , or tumors?

N

2-Chemical properties: -Glucose in urine: (Glycosuria) : : considered as a risk factor for bacterial infection; bacteria utilize glucose during binary fission. -Nitrite in urine: (Nitrituria): : indicates the presence of Coliform bacteria in urine. Note: Enterobacteriaceae species reduce Nitrate to Nitrite.

n

Protein in urine: Proteinuria: - In Pyelonephritis, and lower UTI: Proteinuria (trace from pus or bacterial origin) and Pyuria. - In interstitial nephritis and Glomerulonephritis: Proteinuria , Hematuria, lower number of Pus in urine.

3-Microscopic properties: -WBCs: Normal : 2-3 /HPF. -RBCs: Normal : 3-4 cells/HPF. - Casts: A- Granular , fatty cast, Hemoglobin, and RBCs cast: Acute Glomerulonephritis due to immune system response.

C- WBCs cast: acute pyelonephritis, acute tubulointerstitial nephritis due to infection.

Infective TIN and Infective or Non-infective GN:n

Infective TIN Immune-GN Infective -GN

Pyuria +++++ +Low number.

Urine Culture Positive or negative negative

Nitrite in urine Positive or negative negative

HematuriaHemoglobinuria

Usually negativenegative

+++++++++

Proteinuria Trace from pus and bacteria or tubular origin .

( +++++kidney origin)

Casts WBCs Cast((Neutrophil cast

Hemoglobin or RBCs Casts.