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.