URINARY TRACT INFECTIONS: DEFINITION, CAUSES,TYPES,TREATMENT AND MANAGMENTS
Frequently used term; meaning bacteria inthe urine
Can be ascertained by quantifying the
bacteria in voided urine or in urine obtained
via uretheral catherization.
Indicates that number of bacteria in the voided urine
exceeds the number that can be expected from
contamination from the anterior urethra (i.e, ≥ 105
Refers to significant bacteriuria w/o symptoms
Affecting mostly women in old age groups
A.) Lower Urinary Tract
A syndrome involving dysuria, frequency,
urgency & suprapubic tenderness
B.) Upper Tract Infection
– are acute pyelonephritis, prostatitis, intrarenal& perinephric abscess
– characterized by flank pain or tenderness,fever and often associated with dysuria, urgency& frequency
– however, these symptoms may occur w/oinfection. i.e renal infection or renal calculus.
– Refers to the infection in structurally and neurologically normal urinary tract.
– Refers to infection w/ functional or structural abnormalities (including individually catheters and calculi).
Relapse of bacteriuria
– A recurrence of bacteriuria with the same infecting microorganism that was present before therapy was started and persisted.
A recurrence of bacteriuria w/ a microorganism different from the original infecting bacteriuria.
A new infection
– a sepsis syndrome due to UTI
– Includes evidence of UTI plus 2 or more of the following:
a. temperature: > 38oC or less than 36oC.
b.heart rate : > 90 beats/ min
c. respiratory rate : > 20/min or PaCO2> than 30mmHg
d. WBC : > 12,000/mm,or < than 4,000/mmor > 10% band forms
– kidneys are enlarged especially severe
– with discrete yellowish abscess on the surface
– pathognomonic feature historically
suppurative necrosis or abscess formation within the renal substance.
– or chronic interstitial nephritis
– one or both kidneys contain gross scars due to changes in pelvic wall w/ papillary atrophy and blunting
– its parenchyma shows interstitial ﬁbrosis w/ an inﬂammatory inﬁltrate of lymphocytes, plasma cells and occasionally neutrophils
– tubules are dilated and contracted by atrophy of the lining epithelium,
– tubules contained colloids casts, sometimes called thyroidization of the kidney Papillary Necrosis.
– Affecting the pyramids which replaced by wedge-shaped areas of yellow necrotic tissue with the base
located at the cortico medullary junction.
– as it progress – necrotic papilla may break off proceeding a calyceal deformity
– once with infection, the collecting tubules are ﬁlled w/ bacteria and polymorphonuclear leukocytes.
PATHOGENESIS OF UTI
– urethra is usually colonized with bacteria, especially in women since it’s short & is in proximity to the warm moist
vulvar and perianal areas
– initially starts as colonization in vaginal introitus and periuretheral area > invades bladder > bacteria multiply and then pass up to the ureters (more among with vesicoureteral reﬂux) then to the renal pelvis and parenchyma.
– colonization occurs in massage of the urethra in women and sexual intercourse
– condom use may heighten the traumatic effects
– catheterization of the bladder
– both diaphragm of monoxynal, 9 contraceptive jelly in women and condom catheter in men may predispose to
infection and also spermicides due to adherence of E.coli to vaginal epithetial cells.
– also with estrogen, as predisposing factor to cause recurrent UTI among post-menopausal women due to vaginal
ﬂora changes, its lacto bacilli is replaced by coliform and other uropathogens.
II. Hematogenous Route;
– refers to most common organism is staphylococcus aureus, causing bacteriuria or endocarditis also candida
III. Lymphatic Route
– involves the renal lymphatic once there is increase pressure in the bladder can cause lymphatic ﬂow to the directed toward the kidney
GENDER and SEXUAL ACTIVITY
Sexual intercourse cause the introduction of bacteria into the bladder – onset of cystitis.
Voiding after intercourse reduces the risk of cystitis which promotes the clearance of bacteria
Male population – common source is due to prostatic obstruction and also rectal intercourse
ASB in pregnancy is the presence of >100,000 CFU/mL of the same uropathogen in two consecutive midstream urine specimens or ≥100
CFU/mL of a single uropathogen in one
catheterized urine specimen.
Symptoms attributable to urinary infection should be absent.
2 – 8 % are detected
Usually asymptomatic but once reach the renal pelvis develop pyelonephritis
Due to decrease ureteral tone, decreased ureteral peristalsis and incompetence of the vesico ureteral valves.
Screen ALL pregnant women for asymptomatic bacteriuria once, between the 19th to 17th week age of gestation (AOG), preferably on the 16thweek
A standard urine culture of clean-catch midstream urine is the test of choice in screening for asymptomatic bateriuria.
Urinalysis is not recommended as an initial screening test.
Antibiotic treatment for asymptomatic bacteriuria is indicated to reduce the risk of acute cystitits and
pyelonephritis in pregnancy as well as the risk of low
birth weight neonates and preterm infants
Treatment with antibiotics should be initiated upon diagnosis of ASB in pregnancy. Among the antibiotics
that can be used are nitrofurantoin (not for near term),co-amoxiclav, cephalexin, cefuroxime, fosfomycin, and TMP-SMX (not on the ﬁrst and third trimester)
depending on the sensitivity results of the urine isolate Duration of treatment will depend in the antibiotics that will be used, but short-course (seven days)
treatment is preferred over single-does regimens.
A follow-up urine culture should be done one week after completing the course of treatment Monitoring should be done every trimester untild elivery
Neurogenic Bladder Dysfunction
In spinal cord injury, diseases like tables dorsalis, multiple sclerosis, DM
Due to interference with bladder innervation
Common among children with anatomic
abnormalities of the urinary tract
Some population, reﬂux disappears with advancing age.
But need to have long-term follow-up – might result to failure of renal growth and scarring
Do retrograde psychopathy with contrast media
Bacterial Virulence Factors
E.coli strains O, K & H serogroups
Due to its virulence genes, contains hairlike proteinaceous surface appendages, ﬁmbriae.which adheres to uroepithelial cells of the host. E.coli produce also cytotoxins hemolysis and aerobactin.
E. coli = 80% causing acute infection
fever, sometimes with chills
Urinalysis – midstream urine with at least 10 leukolyte/mm3
Dipstick leukocyte esterase test
– rapid screening test for detecting pyuria
– WBC 10/mm3
c. Microscopic/gross hematuria
ACCEPTABLE METHOD FOR URINE COLLECTION
Midstream clean catch
MANAGEMENT OF UTI
– generally, must treat the infection
– for asymptomatic, must have two cultures
– fear of reinfection and complication especially among DM and other immunocompromised patients and also among elderly patients.
– for children with vesicoureteral reﬂux (if congenital anomalies) can result to stunted growth of the kidneys,
scan formation but rarely renal failure.
– and also pregnant women
– hospitalized patients especially with in dwelling catheters – that is high mortality rates.
Hydration Produces rapid dilution of the bacteria and removal of infected urine by frequent bladder emptying
Acidiﬁcation of urine pH
Nitroformation may be used to lower pH 5.5
Ascorbic acid – but form oxalate stones
With the word of phenazopyridine hydrochloride
– Among patients with renal insufﬁciency – need to modify the dosage according to creatinine clearance especially aminoglycosides
Patterns of response of
Bacteriuria to Antimicrobial
– Deﬁned as (–)urine cultures on hemotherapy and during the follow-up period (usually 1 – 2 weeks)
2. Bacteriologic Persistence
a.) persistence of signiﬁcant bacteriuria after 48 hours of treatment
b.) persistence of the infecting organism in low numbers in urine after 48 hours
– this may occur when the infecting strain is resistant
to the urinary attained e.g. resistant organism or because the levels of the drug are inordinarily low e.g.
not taking the medicine, insufﬁcient dosage, poor intestinal absorption or poor renal excretion among renal insufﬁciency.
3. Bacteriologic Relapse
– usually occur 1 – 2 weeks after the cessation of the drugs.
– also presence of structural abnormalities of the urinal tract
– relapse indicates that the infecting microorganism has persisted in the urinary tract during the therapy.
– after initial sterilization of the urine, reinfection may occur – also called as super infection
Antimicrobial Therapy for
– severely ill – hospitalization
– mild to moderate – may start oral therapy –outpatient
– may start ampicillin or amoxicillin (for gram positive cocci in chain and may use also ﬁrst generation cephalexin
– gram (–)bacillus ﬁrst generation cephalosporin are 35% resistant and also to Trimethoprim –Sulfamethoxazole
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URINARY TRACT INFECTIONS: DEFINITION, CAUSES,TYPES,TREATMENT AND MANAGMENTS.
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