Urinary tract Infections

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.
-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
2-Lack of antibacterial prostatic secretions.
3- Bacterial invasion by sexual intercourse.
-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).
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.
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
-Could be associated with obstruction of renal pelvis.
-Tissue dysfunction or Renal abscess.
-Urinary tract Reinfection:
Recurrent infection when a previously isolated organism
is reintroduced into the urinary tract from the colonizing
gut or genital flora.
Recurrent infection with bacteria that persist within the
urinary tract due to indwelling urologic devices; such as
urethral catheter or nephrostomy tube.
-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.
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.
A-Lower urinary tract infection
(Uropathogenic Escherichia coli).
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
-Short intravesical ureter.
-Incompetent ureteral sphincters.
2-PMN cell influx up the ureter.
D- Bacterial entry through the papillae into the renal
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.
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.
Types of Tubulointerstitial Nephritis:
1-Acute TIN:
- Inflammatory infiltrate and edema affecting the renal
interstitial tissue that often develops during days to
- 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.
-Interstitial renal abscesses :
Necrosis contains neutrophils, and central germ colonies
-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).
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.
mediated disorders,
infections, and
drug interaction.
Glomerulonephritis : GN:
GN: is the inflammation of the Glomeruli of the nephron.
Source of infection: Hematogenous dissemination.
Pathologic feature: One or more renal cortical abscesses.
Insoluble antigen
destruction of the
trapped in the glomerulus
Antibodies attack the
structural components
of the kidney and antigen.
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.
Other infections:
Bacterial: Staphylococci, Streptococcus pneumoniae,
Klebsella, Yersinia enterocolitica, Treponema,
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?
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.
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:
Infective TIN
Infective -GN
+ Low number.
Urine Culture
Positive or negative
Nitrite in urine
Positive or negative
Usually negative
Trace from pus and
bacteria or tubular origin.
WBCs Cast
(Neutrophil cast(
+++++ (kidney origin)
Hemoglobin or RBCs

similar documents