Definitions/Pathogenesis Flashcards
(23 cards)
definition of uti
bacterial invasion of the urothelium
uncomplicated uti
associated with health individuals
no structural or neurological abnormalities of urinary tract
complicated uti
associated with factors that compromise urothelial tract and or host defenses all men pregnant women catheters, stents all hospital acquired infection
recurrent uti
2 in 6 months or 3 in a year
risk factors for symptomatic uti
female menopause sexually active pregnancy spermicide reflux obstruction residual urine immunosuppression catheter renal impairment
pathogenesis of UTI
contanmination /colonisation of periurethral area with pathogen from bowel
ascension through urethra to bladder
penetration and colonisation bladder epithelium
ascension to kidney via ureters
inflammation and damage of kidney epithelium
bacterai cross epithelial cell barrier - bacteraemia
risk factors young women 6
Sexual intercourse
Use of spermicide
A new sexual partner
A mother with a history of UTI
History of UTI during childhood
Blood group antigen secretory status
risk factors post menopausal women 8
History of UTI before menopause
Urinary incontinence
Atrophic vaginitis due to oestrogen deficiency
Cystocele
Increased post-void urine volume
Blood group antigen secretory status
Urine catheterisation
and functional status deterioration in elderly institutionalised women
uncomplicated uti organisms
75% UPEC
around 5% each of kleb, staph sapro, enterococus
then GBS, proteus, pseudo, staph a, candida
bacteria in complicated uti
65% UPEC then 8% kleb 11% enterococcus 7% candida then gbs, proteus, pseudo, staph a
bacterial adherence mechanisms afimbrial
afimbrial adhesions attach organism to target cell polymers polysaccharides glycocalix
bacterial adherence mechanism fimbrial
or pilli
mediate attachment host tissues
type 1 pilli
produced by all strains ecoli
mannose sensitivie
combine with mannose receptors on uromucoid
type 1 pilli
produced by all strains ecoli
mannose sensitivie
combine with mannose receptors on uromucoid
type 2 (p) pilli
mannose resistant
bind to glyolipids of blood group substances secreted by host urothelium
important in pyelonephritis
type s pilli
associated with sepsis, meningitis, ascending uti
antimicrobial resistance
2 types
intrinsic
enzyme - beta lactamase
impenetrable wall
acquired
evolution of new or altered genetic materal through mutations or gene transfer
mechanisms of resistance 3
enzyme inactivation
lactamase hydrolyses beta lactam bond in the antibiotic structure rendering it inactive
altered permeability
receptor activity and transport mechniasms altered to prevent access of antibiotics
alteration of binding site
alter or delete the antibiotic target leading to drug resistance
urinary tract host defence mechanisms in urine 3
ph acid
osmol
mechanical flushing
host defence mechanisms mucosal epithelial 9
commensal bacteria GAG mucin layer TH protein mucosal shedding lactoferrin - chelates irone lipocalin toll like receptors inflammtory response AMPs - defensins
ABU definition
Asymptomatic bacteriuria in an individual without urinary tract symptoms is defined by a mid-stream sample of urine showing bacterial growth ≥ 105 cfu/mL in two consecutive samples in women and in one single sample in men
In a single catheterised sample, bacterial growth may be as low as 102 cfu/mL to be considered representing true bacteriuria in both men and women
% of pregnant women with ABU and % having pyelonephritis
4-7% of pregnant females have ABU – same as normal population
However 20-40% will develop pyelonephritis in pregnancy, usually in third trimester, so ABU should be treated
changes in pyelonephritis
Initially patchy infiltration of neutrophils and bacterial in the parenchyma
Later changes include formation of inflammatory bands extending from renal papilla to cortex
