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
Inflammatory
destruction of the
Glomeruli.
trapped in the glomerulus
Antibodies attack the
structural components
of the kidney and antigen.
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
+++++
+ Low number.
Urine Culture
Positive or negative
negative
Nitrite in urine
Positive or negative
negative
Usually negative
negative
+++++
++++
Pyuria
Hematuria
Hemoglobinuria
Proteinuria
Casts
Trace from pus and
bacteria or tubular origin.
WBCs Cast
(Neutrophil cast(
+++++ (kidney origin)
Hemoglobin or RBCs
Casts.