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MICROBIOLOGY OF

URINARY TRACTINFECTION

Alfred H L toruanNugroho s.s

m. Fatikh nanda

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INTRODUCTIONEpidemiology of UTI by age group and sex

Age Female Male Risk factor

65 40 35 Incontinence, catheterization, prostateobstruction

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DEFENSE MECHANISM OF THE

URINARY TRACT 1. Urine factor :

Urea concentration and high osmolarity

Low pH of urine kill bacteria

2. Hydrokinetic factor :Periodic urinary flow

Dilution of rest urine cause of urinary flow from kidney

Bladder emptying

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3. Mucosal factor :

Mucosa of the bladder consist of more than one layer cellsMucosa of the urinary tract and bladder covered by mucus prevent microorganism attachmentProstatic secretion : has an antibacterial effectSecretion of local IgA prevent attachment of microorganismon uroepithelium later and neutralize toxin produce by

microorganismPerioxidase on the mucosal layer has a bactericidal effect

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PATHOGENESIS Urine : steril Modes of bacterial entry :

Ascending Hematogenous Lymphatogenous Direct extensio n

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PATHOGENESIS

A. Entry is normally by ascent from theurethra

Bacteria invade the urinary tract by ascendingroute through the urethra to infect the bladder andrenal pelvis is the most common.

Occasionally with hematogenous spread

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B. Host factors

The larger number of UTI's present in women thanin men is probably due to the much shorter urethraand the much closer association of the urethrato the anus

Sexual intercourse contributes to the increasednumber of UTI's seen in women

Any anatomic obstruction, or neurologicaldisorder leading to the failure to completely

eliminate the urine can lead to UTIMen in their 40's have problems with the

prostate gland enlarging resulting in obstructionof the urethra followed by incomplete elimination ofurine from the bladder and UTI's

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C. Bacterial factors

>The most important virulence factor of bacteria is theenhanced ability to adhere to uroepithelial cells.

>Pseudomonas infections are both invasive andtoxinogenic

>S. Aureus expresses many potential virulence factorssuch as proteins, enzymes and toxins

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D. Spread to the kidney

Infection of the kidney is due to ascent fromthe lower urinary tract and so any factor leading to retrograde flow of the urine to

the kidney will predispose the host topyelonephritis.Such factors include:

1. Reflux of urine to the kidney

2. Physiological malfunctions3. Urethral catheters

4. Urinary tract stones

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CLINICAL MANIFESTATION

LOWER URINARY TRACT INFECTIONS Acute cystitis : a superficial inflammation of thebladder and urethra

Acute prostatitis occurs when bacteria invade the

prostate

UPPER URINARY TRACT INFECTIONS Acute pyelonephritis is due to bacterial invasion of therenal tissue with inflammation and swelling, sometimescause renal dysfunction

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ETIOLOGY-Escherichia coli , which is responsible for 80 %

of infections that are acquired outside of hospitals

-Other Gram-negative rods such as Klebsiella ,Enterobacter , and Proteus spp. are relativelycommon, each accounting for 3 to 5 % of infections

-Within the hospital environment , Pseudomonas aeruginosa , Serratia marscesens , and otherGram positive bacteria such as Enterococcus faecalis , and Staphylococcus epidermidis are more resistant , common hospital-acquiredphatogens.

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ETIOLOGY - Gram-positive organisms, particularly

coagulase-negative staphylococci andenterococci, cause some infections

- Staphylococcus saprophyticus causesabout 10 % of UTI in young women

- Candida albicans is also a frequentpathogen in hospitalized patients,particularly if diabetes is present

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ETIOLOGYAnaerobes and fastidious organisms rarely causeurinary infections

A number of viruses, particularly mumps virus,cytomegalovirus, and coxsackieviruses, can bepresent in the kidneys and urine, but rare

A number of sexually transmitted pathogens (e.g.,Neiss er ia go no rrho eae ) may invade the urethra.Chlam yd ia t racho m at i s and herpes simplex canpresent with symptoms that mimic acute cystitis inboth men and women

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URINARY TRACT INFECTION

Escherichia coli- The most common cause of UTI- Accounts approximately 80 % of

first UTI in young women- UTI can result in bacteremia with

clinical signs of sepsis- Nephropathogenic E. coli typically

produce hemolysin

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E. coli

Member of the normal intestinal floraMotile, possess polysaccharide capsuleGrow on nonselective mediaRed colonies on Mac Conkey agar

An isolate from urine can be identifiedby its hemolysis on blood agarTemperature for growth : 15 45 0 CSome strains more resistant to heat

viable at 60 0 C 15 minutes ,55 0 C 60minutes

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Klebsiella pneumoniae

-The most clinically important speciesThis bacterium produces large stickycolonies when plated on nutrient media

- Klebsiella's pathogenicity can be attributed toits production of a heat-stable enterotoxin

- K. pneumoniae urinary tract infections arecommon in catheterized patients

- In fact, K. pneumoniae is second only to E.coli as a urinary tract pathogen.

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ENTEROBACTER

Previously : Aerobacter, similar characteristics to Klebsiella, differ in motility

The organisms has small capsule

E. aerogenes may be found free- living aswell as in the intestinal tractE. aerogenes & E. cloacae causes UTI &sepsis

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PROTEUS

Infection in humans only when bacterialeave the intestinal tract

Found in UTI, produce bacteremia, focallesions in debilitated patients or

receiving i.v infusions

P. vulgaris & M. morganii important nosocomial

pathogens

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PROTEUS

P. mirabilis UTI, occasionallyother infectionProduces a typical swarming growthon blood agarIs primarily an opportunist,

transmitted via cathetersProduces a powerfull urease that

hydrolyzes urea toammonia and CO 2

Results in stones and calculi, leading to urinary

tract

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SERRATIA

S. marscescens : is commonopportunistic pathogen in hospitalizedpatient

Causes pneumonia, UTI, meningitis,wound infections, bacteremia &endocarditis specially in narcoticsaddicts & hospitalized patientsOften multiply resistant to

aminoglycosides & penicillinsInfections can be treated with 3 rd generation cephalosporins

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Pseudomonas aeruginosa Opportunistic pathogen of humans.The bacterium almost never infects uncompromisedtissues, yet there is hardly any tissue that it cannotinfect, if the tissue defenses are compromised in somemanner Pseudom onas aerug inosa is a Gram- negative,aerobic rod, belonging to the bacterial familyPseudomonadaceae

P. aeru g in o s a produces two types of soluble pigments,pyocyanin and (fluorescent) pyoverdin.Pyocyanin (from "pyocyaneus") refers to "blue pus"which is a characteristic of suppurative infectionscaused by Pseudom onas aerug inosa .

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Staphylococcus Staphylococci are Gram-positivespherical bacteria that occur inmicroscopic clusters resembling grapesTaxonomically, the genus

Staphylococcus is in the bacterial familyMicrococcaceaeStaphylococci are facultative anaerobesThe bacteria are catalase-positive and

oxidase- negative, can grow at atemperature range of 15 to 45 0C and atNaCl concentrations as high as 15 %

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Staphylococcus

S. aureus forms a fairly large yellowcolony on rich medium; often

hemolytic on blood agarNearly all strains produce the enzyme

coagulaseS. epidermidis has a relatively smallwhite colony, non hemolytic, nearlyall strains lack the coagulaseenzyme

S. saprophyticus Is non hemolytic if culture on blood agar,coagulase-negative, novobiocin-resistant.

Lacks protein A

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Enterococcus faecalis

The enterococci are facultativeanaerobes, produce a small gray colonyafter 24 hour incubation at 35C on sheepblood agar

A small gray colony that is slightly or -hemolytic and sometimes -hemolysis,weakly catalase- positive is a typicalpresentation for Enterococcus

Microscopically, Gram-positive coccioccurring in chains or pairs withindividual cells being somewhatelongated can be presumed to bestreptococci or enterococci

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Microbiological diagnosis

Specimen has to be taken under strict precautions aslower part of urethra is colonized by fecal flora

Thus catheterization is forbidden

Midstream urine is the primary choice, while suprapubicpuncture are alternatives

In special cases after surgery on the kidney, urine istaken by renal catheter.

Urine must be chilled and processed within 2 hours

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DIAGNOSIS

The diagnosis of UTI : based on aquantitative urine culture : > 100,000 colony-forming units (10 5 CFU) per ml of urine, wastermed "significant bacteriuria."This value was chosen because of its highspecificity for the diagnosis of true infection,even in asymptomatic persons.However, several studies have establishedthat one third or more of symptomaticwomen have CFU counts below this level(low-coliform-count infections).They have also shown that a bacterial count

of 100 CFU per mL of urine has a highpositive predictive value for cystitis insymptomatic women

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Bacteriuria indicate UTI

Criteria of UTI1. Bacteriuria with quantitative >100.000 cfu/ml2. Bacteriuria with quantitative

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NUHUN...PISSANN...