Urinary Tract Infections

Urinary Tract InfectionsLaboratory DiagnosisANATOMY OF THE URINARY TRACT

MALEFEMALETypes of SpecimensMid-stream urine (MSU)

Catheter specimen of urine (CSU)

Suprapubic Aspirate (SPA)Note!

This is an invasive procedure and should be used only when highly necessary! Specimen Collection

Note!

Sterility is important! Use a sterile container for collection of urine

Ensure that container is labelled properlyName of patient--------Type of specimen------Date and time of collection-----------------Specimen Collection

Mid stream specimenUrine from indwelling catheter

Specimen CollectionCatheter specimen of urine (CSU)Laboratory ProceduresMacroscopic appearanceMicroscopyCultureAntimicrobial Susceptibility testing of isolatesFoul or strong urine odor may suggest infection

Macroscopic appearance

Clear urine! May suggest the absence of UTI.

This is not always so Cloudy, murky, or turbid (muddy) urine is characteristic of aurinary tract infection (UTI)red or smokey brown urine may suggest the presence of red blood cells

Microscopy

Methods employed:

Wet preparation

Gram stain

Ziehl Neelsen (if indicated in clinical diagnosis)

Other stainsMicroscopy

Slide is examined under the light microscopeWet preparation

bacteriaWhite blood cells(WBCs)

Possible Gram stain results

Gram stain from a cloudy urinePus cells and gram negative bacilliGram negative bacilli (GNB)Pus cellsPossible Gram stain resultsGram stain from a cloudy urinePus cells and gram negative bacilli

Gram negative bacilli (GNB)Pus cellsPossible Gram stain results

Gram stain from a cloudy urineNo pus cells, gram positive cocci in chainsgram positive cocci in chainsPossible Gram stain results

Gram stain from a cloudy urineMany pus cells and gram negative diplococci seen intracellularlyGram negative diplococci within pus cells (intracellular)Pus cellsPossible Gram stain results

Gram negative bacilliBudding yeast cellsSquamous epithelial cellPseudo hyphae of yeastGram stain from a cloudy urineNo pus cells, gram positive ovoid bodies (budding yeast cells)Possible Gram stain results

Gram stain from a bloody urineMany red blood cells, few white blood cells, no organisms seenCulture of urineQualitative analysis

Semi- quantitative analysis

Antimicrobial susceptibility of isolates

What is the organism in the patients urine?Is the organism(s) found of numerical significance?What are the treatment options based on in vitro susceptibility testing?Semi- quantitative analysis

We assume:Significant plate count 100,000 bacteria/ml Doubtful significance >10,000 but 200 colonies (plate count>105cfu/cc) significant plate count on blood agarLactose fermenter on MacConkeys agarConclusion:

Significant growth of a lactose fermenterIdentification of isolatesGram stainBiochemical Reactions etc.

E.g. organism seen on previous slide showed a significant plate count of a lactose fermenter

I.D. Gram stain gram negative bacilli Biochemical Reactions - - Lactose Acid Kligler A/AG - Glucose Acid with gas production - Urease negative - Citrate - positive - Motile - Indole positive Therefore isolate identified as Escherichia coli or E. coliIdentification of isolatese.g. if Gram stain gram positive cocci catalase positive coagulase negativeNovobiocin resistantThen the organism is identified as Staphylococcus saprophyticus

Susceptibility testing- disc diffusion technique

Antimicrobials commonly used include:Naladixic acid (NA)Nitrofuradantoin(F)Sulphamethoxazole trimetroprim(SXT)

Gentamicin (GM)Ampicillin (AM)Augmentin (AMC)Norfloxacin (NOR)Others when there is multiple resistanceSusceptible ResistantReporting:e.g.Direct Microscopy: Many pus cells, few epithelial cells, many gram negative bacilli.

Culture: Significant growth of E. coli plate count > 105 bacteria/cc. Susceptible to/ etc. Resistant to/ etc.Common IsolatesCYSTITISBacterial :E. coli Klebsiella sp.Proteus sp.Pseudomonas spMycotic:Candida albicansParasitic:Schistosoma haematobium

RENAL ABSCESS:

Staphylococcus aureus Mycobacterium tuberculosis E. Coli Proteus sp. Pseudomonas aeruginosa Klebsiella pneumoniaeCommon IsolatesPYELONEPHRITIS/PYELITISE. coli Klebsiella sp.Proteus sp.Pseudomonas spEnterococcus faecalis

IV CATHETER:Staphylococcus aureusYeastKlebsiella pneumoniaeE. Coli URINARY CATHETER:E. coli Klebsiella pnemoniaeProteus sp.Pseudomonas sp.

Identification of common isolates

Escherichia coli:

Colonial morphology: flat dry LFGram reaction: Gram negative bacilliOxidase: negativeKliglers: Acid/Acid GasUrea: negativeCitrate: negativeMotility: MotileIndole: PositiveLysine: Variableflat dry lactose fermenter (LF)Identification of common isolates

Klebsiella pneumoniae

Colonial morphology: mucoid raised LFGram reaction: Gram negative bacilliOxidase: negativeKliglers: Acid/Acid GasUrea: PositiveCitrate: PositiveMotility: Non-MotileIndole: NegativeLysine: Positivemucoid raised lactose fermenter (LF)Identification of common isolates

Proteus mirabilis

Colonial morphology: swarming growthGram reaction: Gram negative bacilliOxidase: NegativeKliglers: Akaline /Acid + H2S+Gas(co2, H2)Urea: PositiveCitrate: PositiveMotility: MotileIndole: NegativeLysine: NegativePPAPositiveIdentification of common isolates

Pseudomonas aeruginosa

Colonial morphology: green pigmentGram reaction: Gram negative bacilliOxidase: PositiveO/FIdentification of common isolates

Staphylococcus spp.

Colonial morphology: white or goldenGram reaction: Gram positive coccicatalase: positiveCoagulase positive (aureus)NovobiocinResistant(saprophyticus)Identification of common isolates

Streptococcus spp.

Colonial morphology: Note type of haemolysis!

Gram reaction: Gram positive cocciCatalase: NegativeAesculin hydrolysis: Positive (Group D Strep.)CAMP test Positive (Group B Strep.)Bacitracin Sensitive (Group A Strep.)

For Group D strep. do further tests to exclude Enterococcus faecalis

Identification of common isolates

Candida albicans

Colonial morphology: white or creamy

Gram reaction: large Gram positive ovoid bodies

Germ tube Positive

THE END