600 likes | 611 Views
This practical class aims to teach students about specimen collection and processing, microbiological and biochemical analysis of urine specimens, culture and identification of organisms, antibiotics susceptibility testing, and interpretation of results. Students will also learn about clinically important etiological organisms associated with UTIs, their identification, and susceptibility testing.
E N D
URINARYTRACT INFECTION MicrobiologyPracticalClass RenalSystemBlock FirstYear Dr.FawziaAl-Otaibi
Objectives Itisexpectedthatbytheendofthispracticalclass,studentsshould beableto: 1. 2. 3. Knowtheimportantstepsinspecimencollectionandtransportto thelab. HowtoprocessurineSpecimensinthelab. –Urinemicrobiologicalandbiochemicalanalysis. –Organismscultureandidentification. –Antibioticsusceptibilitytesting. –Resultsinteroperation. KnowtheclinicallyimportantetiologicalOrganismsassociated withUTI,theiridentificationandsusceptibilitytesting.
SPECIMEN COLLECTION
TYPEOFSPECIMENS Midstreamurine(MSU) Adhesivebag SuprapubicAspiration Cathetersample
SterileUrineContainer Dipslides OnesideisCLEDmedia,the othercanbeMacConkey(MAC) agarorbloodagar.
SPECIMEN PROCESSING
Specimenprocessing: 1.Urineanalysis •Microbiological •Biochemical 2.Cultureandidentification(ID) 3.AntimicrobialSusceptibility testing 4.Resultsinterpretation
1.UrineAnalysis Biochemical Microbiological Macroscopic Microscopic
BiochemicalUrine Examination(Dipstick) •leukocyteesterase •Nitratetest •PH •Glucose •Bilirubin •Protein
TestingforUTI Midstreamcleancatchwithdipstickanalysis Nitrite+→forgram-negativebacteriawhichcanconvertnitrate tonitrite(sensitivity92-100%,lowspecificity); falsenegativewithbacteriathatdonotreducenitrate gram-positivebacteria excessdietaryVitaminC Leukocyteesterase+→indicatespresenceofwhitebloodcells, (sensitivity75-95%,specificity94-98%)– Dipstickresultsmaybeaffectedbymedications/dyes,iepyridium, nitrofurantoin,metronidazole,bilirubin,methyleneblue,VitaminB complex
PhysicalUrineExamination Macroscopic •Color •Odor •Turbidity
MicrobiologicalUrine Examination Microscopic: •Cell-counting(WBC,RBC) •Parasite •Casts (Ovum,Trichomonas,yeast)
MicroscopicUrine Examination(WETMOUNT)
CultureandIdentification Culturemedia Urineinoculationandreadingofculture Identificationofculturedorganisms
CultureMediaRoutinely UsedforUrineCulture
UrineInoculation Quantitative(Colonycounts) +1 +2 +3 +4 aurinesampleisstreakedonsurfaceof BloodAgarplateandCLEDagar/Mc Conkeyagarwithaspecialloop calibratedtodeliveraknownvolume. Overnightincubation Isolationofcolonies, Biochemicaltests, Drugsusceptibilitytest, Overnightincubation RESULT
Smi-QantitativeCultureof UrineSample
IDofculturedorganisms Biochemicaltests. Typeofhemolysis Serologicaltests
CLINICALLYIMPORTANT MICROORGANISMS CAUSINGUTI
EtiologicalAgentsofUTI Bacteria Fungi Parasites
BACTERIA Gram-negativebacilli Enterobacteriace • •Non-Enterobacteriace Gram-positivecocci Staphylococci Coagulase-positive(Staph.aureus) Coagulasenegative(Staph.saprophyticus,Staph. Epidermidis) Streptococci Streptococcus(groupB) Enterococci
GramNegativeBacilli Enterobacteriacae Non-Enterobacteriacae
Enterobacteriacae •Escherichiacoli •Klebseilla •Proteus •Enterobacter •Citrobacter
Non-Enterobacteriacae Pseudomonasspp
GramPositiveCocci Staphylococci Coagulase-positive(Staph.aureus) Coagulasenegative(Staph.saprophyticus) Coagulasenegative(Staph.epidermidis) Streptococcus Enterococci (groupB)
Strept.agalactiae (groupB)
PARASITESCAUSINGUTI Schistosomahaematobium
FUNGICAUSINGUTI Candidaalbicans
Schistosomahaematobium (urine;eggs115-170x45-65micrometers) (primates)
3.Antimicrobial SusceptibilityTesting (AST)
MethodsofAST Diskdiffusiontest Etest
ETEST •E-TEST •Isawell-establishedmethodfor antimicrobialresistancetesting inmicrobiologylaboratories. •Consistsofapredefined gradientofantibiotic concentrationsonaplasticstrip •Usedtodeterminethe MinimumInhibitory Concentration(MIC)of –Antibiotics –Antifungalagents –Antimycobacterialagents
Enterobacteriacae AntibioticSusceptibilityTest •FirstlineUTItreatment: Ampicillin TMP/SMX Ciprofloxacin Gentamicin Amikacin Nitrofunatoin – – – – – –
BacterialResistancetoUTIAntibiotics Nitrofurantoin –E.coli<5% –Otheruropathogens15-20% –Notactiveagainst •Proteus, •someEnterobacter •Klebsiella TMP-SMX(Bactrim) 10-22%variesgeographically Fluoroquinolones(Cipro) therapyforacuteuncomplicatedcystitis Ampicillin –30%ofE.coliresistant
Emergingresistantto AmpicillinandTMP/SMX Interpretation R S S R S S S S Antibiotic Ampicillin Cephalexin Ciprofloxacin TMP/SMX Nitrofurantoin Gentamicin Ceftriaxone Imipenem Organism Source MIC ≥32 ≤4 ≤4 ≥2 ≤16 ≤8 ≤1 ≤1 Ecoli urine