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MICROBIOLOGY OF
URINARY TRACTINFECTION
Alfred H L Toruan
Nugroho 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, prostate
obstruction
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DEFENSE MECHANISM OF THE
URINARY TRACT1. Urine factor :
Urea concentration and high osmolarity
Low pH of urine kill bacteria2. 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 cells
Mucosa of the urinary tract and bladder covered by mucus prevent microorganism attachment
Prostatic secretion : has an antibacterial effect
Secretion of local IgA prevent attachment of microorganismon uroepithelium later and neutralize toxin produce by
microorganism Perioxidase on the mucosal layer has a bactericidal effect
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PATHOGENESIS
Urine : steril
Modes of bacterial entry :
Ascending
Hematogenous Lymphatogenous
Direct extension
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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 and
renal 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 urethra tothe 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 UTI
Men in their 40's have problems with theprostate gland enlarging resulting in obstruction
of 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 and
toxinogenic>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 from
the 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 malfunctions
3. Urethral catheters
4. Urinary tract stones
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CLINICAL MANIFESTATION
LOWER URINARY TRACT INFECTIONSAcute cystitis : a superficial inflammation of the
bladder 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 Proteusspp. are relativelycommon, each accounting for 3 to 5 % ofinfections
-Within the hospital environment, Pseudomonasaeruginosa, Serratia marscesens, and otherGram positive bacteria such asEnterococcusfaecalis, and Staphylococcus epidermidisare more resistant, common hospital-acquiredphatogens.
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- Gram-positive organisms, particularly
coagulase-negative staphylococci andenterococci, cause some infections
-Staphylococcus saprophyticuscausesabout 10 % of UTI in young women
-Candida
albicansis also a frequentpathogen in hospitalized patients,
particularly if diabetes is present
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ETIOLOGY
Anaerobes and fastidious organisms rarely cause
urinary infections
A number of viruses, particularly mumps virus,
cytomegalovirus, and coxsackieviruses, can be
present in the kidneys and urine, but rare
A number of sexually transmitted pathogens (e.g.,
Neisseria gono rrho eae) may invade the urethra.
Chlamyd ia trachomatisand herpes simplex canpresent with symptoms that mimic acute cystitis in
both 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. colitypically
produce hemolysin
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E. coli
Member of the normal intestinal floraMotile, possess polysaccharide capsule
Grow on nonselective media
Red colonies on Mac Conkey agar
An isolate from urine can be identified by itshemolysis on blood agar
Temperature for growth : 15 450C
Some strains more resistant to heat
viable at 600 C 15 minutes ,550 C 60 minutes
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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 toKlebsiella,
differ in motility
The organisms has small capsule
E. aerogenesmay be found free- living as well as in theintestinal tract
E. aerogenes & E. cloacaecauses UTI & sepsis
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PROTEUS
Infection in humans only when bacteria leave the
intestinal tract
Found in UTI, produce bacteremia, focal lesions indebilitated patients or receiving i.v infusions
P. vulgaris & M. morganii
important nosocomialpathogens
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PROTEUS
P. mirabilis UTI, occasionallyother infection Produces a typical swarming growth on blood
agar
Is primarily an opportunist,
transmitted via catheters Produces a powerfull urease that
hydrolyzes urea toammonia and CO2
Results in stones and calculi, leading to urinary
tract
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SERRATIA
S. marscescens: is commonopportunistic pathogen in hospitalized
patient
Causes pneumonia, UTI, meningitis,
wound infections, bacteremia &endocarditis specially in narcotics
addicts & hospitalized patients
Often multiply resistant to
aminoglycosides & penicillinsInfections can be treated with 3rd
generation cephalosporins
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Pseudomonas aeruginosa Opportunistic pathogen of humans.
The bacterium almost never infects uncompromised
tissues, yet there is hardly any tissue that it cannot infect, if
the tissue defenses are compromised in some manner
Pseudomonas aeruginosa is a Gram- negative, aerobic
rod, belonging to the bacterial family Pseudomonadaceae
P. aeruginosa produces two types of soluble pigments,
pyocyaninand (fluorescent) pyoverdin.
Pyocyanin (from "pyocyaneus") refers to "blue pus" which
is a characteristic of suppurative infections caused byPseudomonas aeruginosa.
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Staphylococcus
Staphylococci are Gram-positivespherical bacteria that occur inmicroscopic clusters resembling grapes
Taxonomically, the genus
Staphylococcus is in the bacterial familyMicrococcaceae
Staphylococci are facultative anaerobes
The bacteria are catalase-positive and
oxidase- negative, can grow at atemperature range of 15 to 450C 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 agar
Nearly all strains produce the enzyme
coagulase S. epidermidis has a relatively small
white colony, non hemolytic, nearly allstrains lack the coagulase enzyme
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 onsheep blood agar
A small gray colony that is slightly or-hemolytic and sometimes -hemolysis,weakly catalase- positive is a typicalpresentation forEnterococcus
Microscopically, Gram-positive coccioccurring in chains or pairs with individualcells being somewhat elongated can bepresumed to be streptococci orenterococci
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Microbiological diagnosis Specimen has to be taken under strict precautions as
lower 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 a quantitativeurine culture : > 100,000 colony-forming units(105 CFU) per ml of urine, was termed"significant bacteriuria."This value was chosen because of its high
specificity for the diagnosis of true infection,even in asymptomatic persons.However, several studies have established thatone third or more of symptomatic women haveCFU counts below this level (low-coliform-countinfections).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 UTI
1. Bacteriuria with quantitative >100.000 cfu/ml
2. Bacteriuria with quantitative
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TERIMA KASIH