UTI

Urinary tract infections

(UTIs)
DEFINITIONS
UTI is an inflammatory response of the urothelium to bacterial invasion that is usually associated with bacteriuria and pyuria,
Epidemiology
1 usually relate to age and sex
2 it more common in male infant less 1 year (pre circumcision) after that female have higher incidence
*The morbidity & mort. great at <1y. & >65y.
Bacteriuria is the presence of bacteria in the urine, which is normally free of bacteria & can be symptomatic or asymptomatic
Pyuria, the presence of white blood cells (WBCs) in the urine, is generally indicative of infection and an inflammatory response of the urothelium to the bacterium
Bacteriuria without pyuria is generally indicative of bacterial colonization without infection of the urinary tract.
Pyuria without bacteriuria warrants evaluation for tuberculosis, stones, or cancer
UTIs are a result of interactions between the uropathogen and the host & determined in part by
the virulence factors of the bacteria,
the inoculum size, and
the inadequacy of host defense mechanisms
pathogenesis
Routes of Infection
1-Ascending Route
2-Hematogenous Route
Like TB,staph.Aureus
3- lymphatic
4- direct extension
Host Defence :
1\ compete bladder emptying
2\urinary inhibiter of bacterial adhesion
3\ lining urothelium physical barrier
4\prostatic zinc secration
5\normal periurethral flora of lactobacilli
Bacterial pathogenic factors
1)Adhesion lead to infection
2)Bact .with more adherent property lead to more pathogenic inf.
3)Bacterial fimbiae it 2 types
type 1causing cystitis
Type p pili causing pyelonephratis
Important note more than 80% of UTIs used by E.coli other less likly like klebsiella,proteus,pseudomonas and staph
Alterations in Host Defense Mechanisms
-Obstruction
-Vesicoureteral Reflux
-Underlying Disease
include diabetes mellitus (renal papillary necrosis), sickle cell disorders, analgesic abuse, sulfonamide nephropathy, gout, heavy-metal poisoning, and aging,-Pregnancy
-Spinal Cord Injury with High-Pressure Bladders
Diagnosis
Urinalysis
Urine culture
GUE
Urine Collection
1- voided specimens ,a midstream specimen (representative of the bladder)
2- Catheterized Specimens 3-Suprapubic Aspiration

Macroscopic examination
1-colour &appearance: drugs &food
*red urine does not always signify hematuria.
*cloudy urine, : -amorphous phosphate (the most common cause)-or pyuria
2-specific gravity.1003-1030, dehydration increase it
3-chemical tests
Ph Normaly 4.5 to 8
~ph –uric acid stone in ph less than 6.5 (uric acid soluble in alkaline media)
-RTA failure of kidney to acidify urine , below ph of 6.0
-UTI by urea splitting organism (proteus) ph more than 7.0
~Protein proteinuria more than150mg/24hr
Glucose
glucose in urine if bl. Glucose more than 180 (D.M) or low renal threshold of glucose excretion.
Microscopic examination
Interpretation:
A-bacteria.
B-leukocytes
just as the presence of bact.is not an absolute indication of infection neither is the finding of pyuria.
Pyuria :is the presence of more than 3 leukocytes/hpf
~symptom of uti+pyuria+bacteruria=diagnoses of infection& initiating emperic therapy
One can verify the diagnoses by bacterial culture
-estimate the number of bact.,
-identify the exact organism, &
-predict the drug will be effective in treating infection.
*renal TB. Should be considered in any pt. with sterile pyuria
*urolithiases & malignancy can also cause sterile pyuria.
C- Erythrocytes.
the presence of more than 3 RBCs/ml in urine (hematuria) is abn. &require further investigation. dysmorphic RBCs indicate active glomerular disease result from extreme changes in osmolality affecting RBC during their passage through renal tubules
D-epithelial cells
Sequamous cells-indicate contamination
Transitional cells-of no significance unless abnormal histologically.
E- Casts :formed in the distal tubules & collecting ducts, commonly signify intrinsic renal disease
-leukocyte casts suggest p.n.
-erythrocyte casts =underlying vasculitis or glomerulitis.
-epithelial casts of little significance be differentiated from leukocyte casts.
-hyaline casts of no significance.
-granular casts disintegrated WBC and epithelial cells =intrinsic renal disease
-Crystals of varying importance (cystine, leucine, tyrosine )
IMAGING TECHNIQUES
Radiologic studies are unnecessary for evaluation of most women with genitourinary infections.
Indication including
1-high-risk patients, febrial UTI and most men,
2-acute infectious processes that require further intervention or may find the cause of complicated
infections with possible UT obstruction
3-bacteriuria fails to resolve after appropriate antimicrobial therapy or who have rapid recurrence of infection, abnormalities that cause bacterial
persistence should be sought
-prophylactic to keep the urine sterile
-Suppressive, to prevent already present bact. infecting ut.
PRINCIPLES OF ANTIMICROBIAL THERAPY
Factors important in aiding selection of empirical therapy include whether
-the infection is complicated or uncomplicated;
-the spectrum of activity of the drug against the probable pathogen;
-a history of hypersensitivity;
-potential side effects, including renal and hepatic toxicity; and
-cost
Trimethoprim/Sulfamethoxazole
-mostly used in non complicated UTI
-Antagonism of bacterial folate metabolism it
C.i, folic acid def, G6PD def, pregnancy
Nitrofurantoin
-It have high urinary level but does not obtain therapeutic levels in most body tissues Cephalosporins
-Inhibition of bacterial cell wall synthesis
-They are also useful during pregnancy
Aminopenicillins -Inhibition of bacterial cell wall synthesis have high resistance
Aminoglycosides
-Inhibition of ribosomal protein synthesis
-Their nephrotoxicity and ototoxicity
-When combined with TMP-SMX or ampicillin, aminoglycosides are the first drugs of choice for febrile UTIs
Fluoroquinolones
-Inhibition of bacterial DNA gyrase
-have a broad spectrum of activity that makes them ideal for the empirical treatment of UTIs
- C.I-children, pregnant & lactating F.
BLADDER INFECTIONS
Usually affected female
UTIs in most men should be considered complicated


Clinical Presentation
dysuria, frequency or urgency, supra pubic pain Hematuria or foul-smelling urine may develop
E. Coli is the causative organism in 75% to 90% S. saprophyticus a commensal organism of the skin, is the second most common
Laboratory Diagnosis
1\Urinalysis : WBC,pus, RBCs
2\urine culture : confirm dx, and pathogen
3\Radiology : only in complicated
Treatment
uncomplicated (normally functional and anatomacal) short corse 3-5 days of singal antibiotic
Complicated used multiple antibiotic for longer time
Bact.persistance :persistance same oragnism and same species despite of treat.due to ston,fistula
Reinfection reinfaction by anew ather oragansim which is the most common cause of recurrent UTI
Acute Pyelonephritis
1\inflammation of the kidney and renal pelvis, the diagnosis is clinical.
C.F:
common in female
High grad fever with riger
Renal angle tenderness
Lower tract symp.like dysuria,frequency
Sepsis
Children have diffuse abdom. Pain,failure to thrive or asymptomatic
Investigation
Urinalysis :WBC,RBC
Leukocytosis .increase ESR
Urine culture :80% E.coli
Blood culture : +ve in 2/3 of cases
Radiological images A- u/s B-CT with contrast C-radioistop
Management
10-30%of pt need admission
1- Empiric Rx :Ampiciline IV +Aminoglycoside or 3rd genereation .cephalosprine or fluroquinolones
2-shift to antibiotics based on culture
If -ve bacteraemia then continue paranteral Ab for 3-5 day and change to total 10-14 days
If +ve bacteraemia continue paranteral Ab for 7-10 day then oral to 10-14 days
less toxic could treated as out patient with oral flouroquinolone or TMP-SMX for 10-14 days
If fever for>3day on Rx then suspect renal abscess
Some pat need follow up by :Urine culture and Radiological exam like Voiding cysto urethrography
Differential Diagnosis Acute appendicitis, diverticulitis, and pancreatitis can cause a similar degree of pain, but the location of the pain often is different