UTIs are common, especially among women UTIs in men are less common and primarilyoccur after 50 years of age UTIs infection usually occur by ascendingroute (urethra to bladder) UTIs infection is less common byhaematogenous spread (kidney) UTIs occur in two general settings:community-acquired and hospital (nosocomially)acquired
1.2% in women- 0.6% in men- 50% of women will experience an UTI duringtheir lifetime.- Nearly 30% women will have had a symptomaticUTI requiring antimicrobial therapy by age of 24.
•UTI-Presence of microorganisms in the urinarytract including the bladder ,prostate, collectingsystem or kidneys.•Significant bacteriuria-colony count of 105CFU/ml or greater depending on the clinicalsetting ,manner specimen were collected.• Pyuria - Presence of pus cells in urine(more than 10 cells/HPF)
Infection ContaminationMore than 105 Organisms/ml less than 104 Organisms/mlA single bacterial spp More than one organism•Bacteriuria –presence of bacteria inthe urine.True infection or contamination.
Female MaleAll ages Previous UTI LACK ofcircumcisionUrethralcatheterizationdoNeurogenicbladderdoUrinary tractobstructiondoRenaltransplantationdoUrologicinstrumentationdo
Adults Sexual intercourse Rectal intercourseLower socioeconomicDiabetes , surgerySickle cell trait inpregnancyHIV high viral loadOlder age Functional andmental impairmentProstaticenlargement
1.Age and sex –infants 1-2% Boys –first 3 months Thereafter more often in girls2.Stagnation of urine in the bladder3.Inadequate fluid intake4.Structural abnormality5.Vesico –urethral reflex6.Antibiotic treatment –Penicillin7.Lactobacilli –urethral syndrome.
Host defences: Urinary bladder is usually resistant to bacterialcolonisation. Bacteria accessing the bladder are eliminatedby -Flushing mechanism-Urine inhibitors (PH, osmolality, urea)--Uroepithelial defences (cytokines,PMNs)-Tamm- Horsfall protien
UTIs are a result of interaction between the uropathogenand the host. Successful infection of the urinary tract is determined byvirulence factor of bacteria, inoculum size, inadequacy of host defense mechanisms. These factors play a role in determining the ultimatelevel of colonization and damage to the urinary tract.
Bacterial virulence factors Adhesins Toxins (Hemolysin-A) Proteases Invasins Serum resistance factors or Motility mediators. UPEC strains produce an acid polysaccharidecapsule that protects the bacteria from phagocytosisand inhibits activation of complement
1.Urethritis-: Infection ofanterior urethral trat.dysuria, urgencyand frequency ofmicturition2..Cystitis-infection ofbladder Frequency, dysurea ,urgency. Suprapubicdiscomfort +/-tenderness. Fever is often absent.
3.Asymptomatic bacteriurea-isolation of aspecified quantitative count of bacteria in anappropriately collected urine specimenobtained from a person without symptomsor signs of urinary infection.4.Acute urethral syndrome-seen in young,sexually active women,who experiencedysuria ,frequency and urgency but yieldfewer organisms than 105 cfu/ml urine onculture.
5.Pylonephritis –inflamation of kidneyparenchyma ,calyces and pelvis . Fever, abdominal pain, vomiting. Dysuria ,frequency, flank or loin pain. Flank or loin tenderness. In elderly: symptoms are often atypical. Bacteremia is common.
INDICATION-1.Epidiomologicalpurpose2.Diagnosis of infection
1.Clean catch technique-Female – periurethral area iscleaned with soap and waterLabial folds are than retractedUrethra is flushed by voidingthe first portion of urineMid stream urine is collected ina sterile container andprocessed within 1 hr.
Non invasive methods aresafe and ideal Follow the Broom hallmethod,By tapping just above thepubis with two fingersplaced on supra pubicregion after 1 hour offeed, tapping on at therate of 1 tap/second for aperiod of 1 minute, if notsuccessful tapping isrepeated once again.The child spontaneously passthe Urine and to becollected in a sterilecontainer
Mycobacteriumtuberculosis-entire quantity of firstmorning urine sampleis collected for threeconsecutive days.2.Straight catheterizedurine3.Suprapubic bladderaspiration4.Indwelling catheter
Collected urine sample transportedimmediately and cultured within 30mins . If delay –refrigerated at 40 c or preserved usingboric acid 1.8% ,cultured within 24 hrs. Urine transport tube containing boric acidglycerol and sodium formate -24 hrs.
Enzyme linked immunosobent assay fordetection of immunoglobulin for diagnosis ofUTI Flurorescent antibody technique DNA probe test.
Required when urine contain bacteria, cells, casts,protein,nitrite Nutrient agar, CLED agar, Blood agar and MacConkey’s medium at 37°C CHROMOGENIC AGAR – Direct detection anddifferentiation of pathogens on primary plate.
- Isolated colonies are identified in a systematicway:1. Microscopical examination : Gram staining to differentiate between Gramnegative and Gram positiveShape, size and arrangement2. Biochemical reactions :- For Gram negative organisms: Sugarfermentation, Indol test, Oxidase, MR, VP andurease tests- For Gram positive organisms : Coagulase test,catalase test
3.Serological identification : Detection ofmicrobial Ag by specific Ab Detection of significant numbers ofpathogenic bacteria from culture of theurine remained gold standard , diagnosisof UTI
KASS defined ->105 cfu/ml ,significant inwomen –pylonepritis or asymtomaticbacteriuria Single voiding ,105 colonies /ml -80% -trueinfection. Same organisms recovered from two separatespecimens 90-95% <104 colonies/ml -98% -no infection 104 -105 colonies/ml –sample repeated.
A. QUANTITATIVEQuantitative criteria distinguish bacterialinfection or colonisation of the urine fromcontamination.Criteria depends on the fact that the density of thebacteria in infected urine is usually severalorders of magnitude higher than the density ofbacteria in contaminated urine.1.Pour plate technique2.Surface viable count
B.SEMI QUANTITATIVE1.Standard loop technique2.Filter paper method(blotting paper)3.Dip spoon method4.Dip slide method5.Agar cup method6.Pad culture method7.Swab culture method.
Principle Inoculating loop ofstandard dimensions Fixed known volume ofmixed uncentrifugedurine Spread over the agarplate, inoculated. Number of coloniescounted or estimated Number used to calculatethe number of viablebacteria /ml of urine procedure
Interpretation Presence of 100 or more colonies –significantbacteriuria.
Standard 6mm wide stripof filter paper bent into Lshape with 12mm longfoot , sterilized at 160degree for 1hr. Dip the whole of theangulated end foot Uncentrifuged sample ofurine Press over the agar plate Remove the strip,incubate Count the coloneisgrowing on theimpression area.
Interpretation Upto to 50 colonies may be countable and heaviergrowth are noted as semiconfluent or confluent. Approximately ,105 bacteria /ml corresponds -25colonies of bacilli ,30 colonies of cocci. Merit Rapid and economical ,8-10 sample can be tested Demerit Growth –confluent.
Procedure Small plastic tray carrying a layer of anappropriate agar culture medium on bothsurfaces provided with container with screwcapped. dip slide is immersed in urine sampleand removed and placed in container screwcapped ,incubated. Commercial supply of dip –slides providecharts showing representative number andpatterns by comparison with which viablecount can be read.
Merit Least laborius,inexpensive,convinient forscreening large no of samples,inoculation doneat the site itself ,problems with transport ofurine are overcome.Demerit Does not provide material for microscopicexamination Difficult to judge ,pure or mixed confluentgrowth.
Similar colonies found in numbers suggestingsignificant bacteriuria should be identified bystandard procedure 102 cfu/ml-symptomatic patient –significant. 104 -105 cfu/ml –-when multiple species are recovered- depends on clinical presentation.
Antibiotic sensitivitycarried out dependingupon isolate andclinical condition ofthe patient. Orally administereddrugs are tested –ambulatory Parental drugs tested–oral drugs can not betaken.
- Presence of pus in urine in absence of bacterialgrowth- Causes :a- Infection with: Chlamydia trachomatisM. tuberculosisUreaplasmaAnaerobic bacteriaMycoplasma and L-formsVirusesb- Previous antibiotic therapy(Suppress growth of bacteria)
Uncomplicated UTI:Trimethoprim/SulfamethoxazoleNitrofurantoin Complicated UTI (Pyelonephritis):Treatment with a systematic antibacterial agente.g. Beta-lactam (Ampicillin, amoxicillin, cefalexin)Quinolone (Ciprofloxacin, levofloxacin)
Text book of microbiology-Ananthnarayan Practical medical microbiology-Mackie andMcCartney Diagnostic microbiology-Bailey and scott’s Text book of medical microbiology –DAVIDGREENWOOD Text book of diagnostic mirobiology-KONEMAN’scolor atlas Text book of microbiology-jawetz MANDELL text book of infectious diseases HARISSON text book of internal medicine INTERNET