microbology of urinary track infection kel 1 revisi

7/28/2019 Microbology of Urinary Track Infection Kel 1 Revisi

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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

microbology of urinary track infection kel 1 revisi

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