泌尿系統(tǒng)感染Urinary_tract_infection(1)

1、.Urinary Tract InfectionsUrinary Tract Infections.UTI UTI - common affliction for which patients seek medical attention UTI can occur from infancy through old age more common in females than males 20% of all females will experience a UTI during their lifetime.UTIDefinitionsThe term “UTI” represents

2、a wide range of clinical syndromes Bacteriuria: the presence of bacteria in urine - does not necessarily imply infection Asymptomatic bacteriuria: presence of bacteria in the urinary tract in the absence of symptoms - clinical significance controversial outside certain patient populations - pregnant

3、 women - patients undergoing invasive procedures of the urinary tract .UTIDefinitions Cystitis: UTI presumed to be confined to the bladder - painful/burning urination - urgency or frequency - absence of symptoms or physical signs suggesting inflammation at other sites within the urinary tract Note:

4、clinical criteria are notoriously inaccurate in identifying the actual anatomic site of infection.UTIDefinitions Pyelonephritis: clinical diagnosis which implies a more invasive infection- inflammation of the kidney and renal pelvis is assumed to be present when patients have pain or tenderness invo

5、lving the flank, together with other clinical or laboratory evidence of UTI-fever, nausea, chills, malaise, headache, etc.UTIDefinitions Prostatitis: inflammation / infection of the prostate gland - may present as acute or chronic Intrarenal abscess / perinephric abscess: collection of pus in the ki

6、dney or in the soft tissue surrounding the kidney.UTIDefinitions Complicated infections - underlying abnormality that predisposes patient to UTI or makes UTI more difficult to treat effectively Recurrent Infections Relapse - recurrence of infection by same organism after discontinuation of treatment

7、 Reinfection - recurrence of infection by a different organism after discontinuation of treatment.UTIPathogenesis UTI usually due to patients own intestinal flora - ascending route of infection - organisms enter the urinary tract in a retrograde fashion via the urethra Complicating factors such as c

8、atheters, nephrostomy tubes, surgery, urinary stones, etc - allow organisms to enter and persist in urinary tract - alter the typical spectrum of organisms - may have multiple etiologies.UTIPathogenesis Elderly patients - incontinant - functionally impaired - postmenopausal changes - neurological al

9、terations Pregnant women - altered anatomy Hematogenous route - endocarditis, bacteremias, tuberculosis - disseminated infections.UTIEtiology Majority of UTI are due to a single pathogen The Enterobacteriaceae responsible for 90% of all UTI- gram negative bacilli- facultatively anaerobic- common int

10、estinal floraEscherichia coli most commonly isolated pathogen 80% of all UTI .Community-Acquired UTIProteusS.epi &gm - entericsEnterococcus.Uro-pathogens E.coli, Klebsiella spp.-intrinsic gut organisms-highly motile-produce fimbriae (pili) attachment Proteus, Morganella, Providencia-Urease producing

11、 organisms-increases urinary pH - leads to crystal formation biofilmscolonization of catheterprotects bacteria from host defenses & antibiotics.Nosocomial UTIcatheter associatedShort TermLong TermPseudomonasPseudomonasProteusProteusEnterobacterCandidaProvidenciaMorganellaEnterococcus.Urinalysis usua

12、lly have increased numbers of WBC leukocyte esterase test is often positive nitrate test is often positive.Urinalysis Urine culture: significant bacteriuria usually defined as 105 bacteria / ml. (108 / litre) lower numbers may be significant in children and in catheter collected specimens.Specimen c

13、ollection Should all patients with a suspected UTI be cultured? Community acquired vs nosocomial? Should all isolates be identified?Susceptibility testing?.Specimen collection Clean catch mid stream specimensClean catch mid stream specimens - most frequently used method - urethra cleaned prior to co

14、llection - first void urine allowed to pass to clear urethra - mid-stream collected in sterile container Collection bags (children)Collection bags (children) - used in young children lacking bladder control - often contaminated - most meaningful result is a negative culture.Specimen collection Supra

15、pubic aspiration / straight cathetersSuprapubic aspiration / straight catheters - invasive - specimen obtained directly from bladder Indwelling cathetersIndwelling catheters - urine obtained by inserting needle into catheter or through diaphram - preferable to obtain specimen from new catheter, rath

16、er than old catheter.Specimen transport Sent to and processed by lab as quickly as possible- Require: method of collection time of collection patients antibiotics Specimens not received by lab in 1-2 hours MUSTMUST be refridgerated Urines not received within 24 hours or not refridgerated will be rej

17、ected by laboratory.Antimicrobial Therapy Empiric Therapy - based on most probable pathogens - local rates of resistance - acute infection vs chronic - reinfection or relapse - indwelling catheter etc.Management of UTIAnatomical/Functional Predisposition to UTI Impaired bladder emptying Dysfunction

18、Neuropathy VUR BOO Diverticulum.Management of UTIAnatomical/Functional Predisposition to UTI Obstruction Any level VUR Calculi very difficult to eradicate if UTI and stones.Management of UTIAnatomical/Functional Predisposition to UTI Intrarenal Renal scars Interstitial nephritis Papillary necrosis M

19、edullary sponge kidney APKD Congenital calyceal obstruction.Management of UTIAnatomical/Functional Predisposition to UTI Associated conditions Diabetes mellitus Pregnancy Immunosuppression Elderly.Management of Female UTIBacterial Factors Adherence Adhesins Fimbriae Non-fimbrial Adhesins Biofilms Im

20、portant in catheter UTI Soluble Virulence Factor Production Disrupt bladder protective mucus layer.Management of Female UTI Bacterial Factors Iron Acquisition Mechanisms Siderophores and Haemolysins Allow growth Serogroup and Serum R O ag LPS outer G -ve Prevent complement destruction Capsules K ag

21、covers bacteria capsule Protects v phagocytosis and complement attack.Management of Female UTI Bacterial Factors Ig Proteases Cleave gut IgA Ureteric Paralysis P. Fimbriae and endotoxin Motility Ascent of LUT Urease Production Hydrolyse urea and increases ammonia which increases bacterial adherence.

22、Management of Female UTIHost Factors Colonisation of vagina, introitus, urethra Biological predisposition Hormone deficiency vaginal atrophy Spermicidal jelly increases vaginal pH Antibiotics reduce vaginal lactobacilli and increase pH Ascent to bladder Sexual milkback Catheterisation.Management of

23、Female UTIHost Factors Establishment of bacteria in bladder Urine composition (extremes inhibit bacterial growth) Reduced IgA and IgG Reduced GAG layer in the bladder Low urine flow Incomplete emptying.Management of Female UTIMSSU when symptomaticUSS renal tract with post void residualKUBTargeted fl

24、exible cystoscopy (8% yield) macroscopic haematuria microscopic haematuria between UTIs persistent UTI.Management of Female UTI3 days oral antibiotics or x1 high dose if compliance poor14 days antibiotics if pyelonephritisAddress any underlying cause (rare)General advice increase fluid intake cranbe

25、rry juice void before and after si.Management of Female UTIHygiene wash without soap pat or air dry cotton pants6 months low dose prophylactic antibiotics alter gut flora may affect COCPSelf-start antibiotic therapy.Management of Male UTIMSSU when symptomaticUSS renal tract with flow rate and post void residualKUBFlexible cystoscopy macroscopic haematuria microscopic haematuria persistent UTI.Management of Male UTIUTI - 7 days oral antibioticsAddress underlying cause.Management of Childhood UTIHistory fev