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URINARY TRACT INFECTIONS

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Please supplement and learn theory on the basis of the lecture, Mim’s book and supplementary

materials before class!!!

URINARY TRACT HOST DEFENSES

URINE MUCOSAL IMMUNITY

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Urethral flora

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ENDOGENOUS

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RISK FACTORS

transm

ission

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URINALYSIS = ……………………………………………………………………………………………BACTERIURIA = ………………………………………………………………….PYURIA = ……………………………………………………………………………HEMATURIA = ……………………………………………………………………ASYMPTOMATIC BACTERIURIA = …………………………………………………………………………………………..UROSEPSIS = ……………………………………………………………………………………………

IMPORTANT TERMS

Upper: …………………….

Lower: ………………………………….

UTI


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UTI

ETOLOGY

Enterobacteriaceae:………………………………………………………………………………………………………………………Non-fermenative rods:……………………………………….……………………………………….……………………………………….……………………………………….

GN RODS

GP COCCI

MISCELLANEOUS

OBLIGATORY ANAEROBIC

FUNGI

VIRUSES

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Catheterization

SHORT TERM……………………..

LONG TERM……………………..

CA-ASB…………………………………………………………………….

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CA-UTI……………………………………………………………………

ETIOLOGY

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CA-UTI are often caused by:

• ……………………………………………………• …………………………………………………..

CA-UTIGROUPS OF ANTIMICROBIALS

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Symptomatic …………………………


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DIAGNOSIS OF UTIS

Patient’s sample URINE

collection

SUPRAPUBICASPIRATION

CATETHERVOIDED

infection if

≥ 10 5 CFU/mL ≥ 10 5 CFU/mL any number

PROHIBITIONS1. URINE SAMPLE MUST NOT BE TAKEN FROM A URINE BAG IN PATIENTS WITH

CATETHER2. URINE SAMPLE MUST NOT BE STORED OR TRANSPOTRED AT RT

Asymptomatic bacteriuria is not

routinely screened for or treated in women who are not pregnant, men,

young people or children

Asymptomatic bacteriuria is routinely screened for and treated only if is considered a risk factor in clearly defined situations : pregnant women and patients with:diabetes, neutropenia, polycystic kidneys disease, kidney transplant, and individuals with functional or structural anomalies of urinary tract

Specimen collection There are three ways of urine sample collection

1. Clean catch midstream urine 2. From indwelling catheter 3. Suprapubic Aspirate

Specimens transport Because urine is an excellent culture medium for bacteria, urine specimens must be sent to the laboratory as soon as possible at a refrigerator temperature (40C). Specimens should be plated on culture media within 2 hours of collection or bacterial counts will not be valid. If this is not possible, the specimen may be refrigerated for a maximum of 4 hours before plating. Specimens should not be allowed to sit out on counter tops, since aerobic bacteria double about every 20 minutes at room temperature, causing false-positive results on microscopy, dipstick urinalysis, and culture.


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DIAGNOSIS

GRAM STAINING

CULTURE

RAPID TESTS

one drop of urineunder microscope ≥ 1 bacterium per OIF =

bacteriuria ≥105CFU/mL)

≥ PMN cell per OIF = PYURIA

OIF = oil immersion field

Small loop0.001 mL

Big loop0.01 mL

MacConkey agarOR BLOOD AGAR

e.g. 10 colonies

10 x 1000=105 CFU/mL

10 x 100=103 CFU/MLPOSITIVE=growth

≥105CFU/mL

95% patients1 BACTERIAL

SPECIES

≥3 different bacterial species

=CONTAMINATION

POSITIVE growth but NO pyuria= CONTAMINATION* with exceptions

* Atypical or fastidious bacteria or interstitial pyelonephritis/cystitis

Leukocyte esterase

Nitrite

Dipstick analysis

PYURIA

BACTERIURIA*(some bacteria do not produce nitrite: S. saprophiticus, Enterococcus spp. P. aeruginosa)

Urinalysis: pH, glucose, proteins, PMNs, red blood cells, creatinine etc.

Directions of laboratory testing of urine samples: a) microscopy – Gram stain of unspun urine b) aerobic culture, identification and antimicrobial susceptibility testing c) rapid tests – dipstick analysis of urine, URICULT d) serology - not applicable e) molecular techniques – NAATs (for fastidious organisms)

A. Gram stain of uncentrifuged/unspun urine. The Gram stain is the easiest screening method. One drop of uncentrifuged urine is placed on a slide and allowed to dry without spreading. The slide is than Gram stained and examined under oil immersion. The presence of one or more bacteria per oil immersion field (OIF) correlates with a bacterial count ≥105 CFU/ ml. The presence of one or more PMNs per oil immersion field indicates pyuria. The Gram stain cannot detect bacterial counts of less than 105 CFU/ ml so it is an insensitive test and should not be used in patients with complicated UTIs. B. Quantitative Cultures Quantitative cultures should be performed on all urine specimens so that the number of bacteria per milliliter of urine can be determined and expressed as CFU/ml. Interpretation of Culture Results To determine whether bacteria isolated from urine cultures are contaminants or clinically significant agents of UTI, some criteria must be considered, including the identity of the isolate, the number of bacterial types, the type of specimen, and the colony count.


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1. Type of organism Lactobacillus species, alpha-streptococci, and diphtheroids are not associated with UTI and should not be identified or have susceptibility tests performed. They are regarded as urethral or skin contaminants, no matter what is their colony count.

2. Number of bacterial type 95% of all UTI infection are caused by one type of organism, and it is unlikely that 2 organisms are involved. It is almost impossible that 3 organisms are involved although exceptions do occur (exceptions include catheter-associated UTIs). Cultures containing 3 or more than organisms are generally considered to be contaminated.

3. Urine cultures: If urinalysis is negative for pyuria, positive cultures are likely contamination. Positive cultures with pyuria are defined as 100,000 (≥105 CFU/mL; colony forming units per mL) colonies. This cutoff is the most sensitive for a true UTI. Situations in which lower colony counts <105 are significant include: ► patients who are already on antibiotics at the time of culture ► symptomatic young women ► suprapubic aspiration ► and men with pyuria

Colony counts and specimen type Clean catch or indwelling catheter specimens Because clean catch or indwelling catheter specimens are collected through the urethra, the urine is likely to be contaminated by normal urethral flora, and the colony counts are necessary for interpretation of culture results. In general: a) counts less than 104 CFU/ml indicate contamination

b) counts of 104–105 CFU/ml indicate possible infection c) counts greater than 105 CFU/ml indicate significant bacteriuria and infection

Colony counts less than < 105 CFU/mL of urine can be significant in at least 4 situations (Table 1):

Patients with pyelonephritis, in whom the bacteria are multiplying mainly in the kidneys rather than in the urinary bladder, not infrequently show colony counts less than <104 CFU/mL

Patients with symptoms of lower urinary tract infection have low colony counts, which may indicate the “urethral syndrome”

Low colony counts can also be important in patients with prostatitis and epididymitis Low colony counts can be important in patients with fungal urinary tract infection

GOLD test – detects antibacterial factors (e.g. drugs metabolites) present in the urine specimen that may inhibit or affect bacterial growth, producing false-negative results. C. Screening methods and rapid tests used to diagnose UTIs Gross inspection of urine Urine can be cloudy because of the presence of white blood cells (>200 per mL), red blood cells (>500 per mL), bacteria (>106 per mL), fat or sediment such as crystals (struvite). Crystals are more prominent in alkaline specimens. The urine of patients with clinical UTI is typically cloudy, but cloudy urine is not synonymous with UTI.

The most commonly used criterion for defining significant bacteriuria

is the presence of ≥105 CFU per milliliter if urine


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Dipstick analysis of urine Rapid dipstick techniques as a supplement to or substitute for traditional methods of diagnosis based on microscopy and culture. Chemical reagents on separate test pads of the dipstick evaluate different properties of urine, such as pH, glucose and protein content, and the presence or absence of white blood cells (pyuria), red blood cells (hematuria), and significant bacteriuria. The procedure is to dip the stick into fresh, unspun urine, covering all of the test pads. The strip is then withdrawn immediately along the edge of the container in such a way as to remove any excess urine. It should be held horizontally before being read, in order to prevent mixing of the reagents in adjacent pads. Storage and use of dipsticks should be according to the manufacturer's recommendations. 1) Leukocyte esterase (LE) indicates white blood cells in the urine. The leukocyte esterase test detects pyuria, which correlates with bacteriuria. The test identifies the presence of the enzyme leukocyte esterase which is produced by leukocytes. This test has a reported 75% to 96% sensitivity and a 94% to 98% specificity for detecting pyuria. False-positive tests are usually caused by contamination, often by vaginal secretions. False-negative specimens can be caused by hypertonic urine (as determined by high specific gravity), glycosuria, and urobilinogen, in case of ketonuria, proteinuria, during treatment with tetracycline, gentamycine, and after high doses of vitamin C administration. The sensitivity of the LE dipstick test can be increased by combining it with the nitrate test.

2) The nitrite test is used to screen for significant bacteriuria. It is based on two observations: (a) normal urine contains nitrates but not nitrites; and (b) about 90% of bacterial species causing UTI can convert urinary nitrates to nitrites. The nitrite test has a 92% to 100% sensitivity for UTI but only a 35% to 85% specificity. It is most useful for detecting >105 CFU/mL of aerobic GN rods. The nitrite test is especially useful in patients with indwelling urinary catheters to determine whether or not they are infected. In children, the

sensitivity of the nitrite test is high (up to 98%) but specificity is lower (29% to 44%) than in adults. False-positive tests can result from substances that cause red urine such as the ingestion of beets in susceptible subjects or the bladder analgesic phenazopyridine. False-negative nitrite tests can occur in “low-count” UTI (<105 CFU of bacteria per mL of urine), infections caused by bacteria that do not produce nitrites (such as enterococci, Staphylococcus saprophyticus, and Pseudomonas aeruginosa), short bladder dwell time, dilute urine specimens, or acid urine. The nitrate test is not sensitive enough to be used alone. 3) Pyuria (more sensitive than leukocyte esterase): >5-10 WBC/hpf per ml (high power field in microscope – for urine objective 40x) or >27 WBC/ml. Sterile pyuria (positive urinalysis, but negative urine culture results) should be considered in cases of interstitial nephritis or cystitis, and infection with fastidious organisms such as Mycobacterium tuberculosis or atypical mycobacteria, Chlamydia trachomatis, Ureaplasma urealyticum, Mycoplasma hominis, M. genitalium, M. fermentans (in HIV-positive patients), fungi, viruses. URICULT: semiquantitative screening for bacteriuria in urine (description in the supplementary materials)

http://www.mondofacto.com/facts/dictionary?query=glycosuria

http://www.mondofacto.com/facts/dictionary?query=urobilinogen


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Urinalysis Urine culture Interpretation Pyuria-positive Positive ≥105

CFU/ml one bacterial species

Infection of UTI

Pyuria-positive Positive <105

CFU/ml

Infection of UTIs should considered in cases: ► the urine specimen was obtained via suprapubic aspiration ► in patients with pyelonephritis, prostatits/epididymitis, urethritis/urethral syndrome, fungal UTI ► patients is on antibiotic therapy – Gold test + ► symptomatic young women/ pregnant/children/men with pyuria

Pyuria-positive Negative

Infection of UTIs should considered in cases: ► interstitial nephritis/cystitis ► infection with fastidious organism: M. tuberculosis or atypical mycobacteria, Chlamydia trachomatis, Mycoplasma spp., Ureaplasma spp., Corynebacterium urealyticum, fungi (Candida spp.), viruses (BK, adenovirus, CMV)

Pyuria-negative Positive polymicrobic one bacterial species (~105 CFU/ml)

Contamination Immunosupression

Pyuria-negative Negative Non-infectious etiology

Student notes

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TREATMENT

UTITHERAPY

Community-acquired Hospital-acquired

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GROUPS OF ANTIMICROBIALS USED:

Spectrum:……………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………..

GROUPS OF ANTIMICROBIALS USED:

Student notes

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CLASS TASK Aerobic culture of urine specimen using calibrated loops (semiquantitative method) The most common method uses a calibrated platinum loop that delivers 0.001 ml or 0.01 ml of urine. Each plate is inoculated with one loopful of urine, and the colony count is determined by multiplying the number of colonies by the dilution factor (the volume of loop). For example, if a 0.001 ml loop is used and 10 colonies are observed, the colony count would be 10 x 10000 or 10,000 CFU/ml (104 CFU/ml). If a 0.01 ml loop is used and 10 colonies are observed, the colony count would be 10 x 100 or 1000 CFU/ml (103 CFU/ml). The following procedure is used to perform a quantitative culture of urine using a calibrated loop

1. Mix the urine sample well 2. Vertically insert a flamed and cooled calibrated loop into the specimen and immerse it just below

the surface of the specimen. Only move the loop straight up and down 3. Remove a loopful of urine and inoculate each plate by making a straight line down the center and

then a series of close perpendicular streaks through the first line. Inoculate each plate (MacConkey agar for GN rods and blood agar for GP cocci and fungi) with one loopful of urine

4. Incubate the media for 24 hrs

1. Your patient is a 25 years old pregnant women with acute UTI. She delivered morning voided urine sample to the laboratory. Your task: 1. Plate urine sample from your patient using calibrated loops: a) small loop – one half of MacConkey agar and one half of blood agar b) big loop – one half of MacConkey agar and one half of blood agar Label plate with your initials and number of sample and incubate 24 h at 37° C. 2. Estimate growth (how many bacterial species is growing on culture media) and what is the number of bacterial colonies (count bacterial colonies), and record results: a) number of bacterial species ------------------------------------------------------------ b) number of bacterial colonies ----------------------------------------------------------- How bacteria isolated from patient’s urine sample may be indentified to species?

a) Gram-staining-----------------------------------------------------------------------------


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b) other tests (propose some) ------------------------------------------------------------

----------------------------------------------------------------------------------------------- 3. Which groups of antimicrobials may be used to treat the infection caused by the isolated microorganism taking into consideration the fact that your patient is pregnant? What mechanisms of resistance isolated species may present? ------------------------------------------------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------------------------------------------------ Amoxicillin – S Trimetoprim – S Cefuroxime – S Norfloxacin – S Nitrofurantoin – S ESBL – negative 4. What complications may occur if the infection will not be treated properly? --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- 2. Your patient is a 73-years old men hospitalized because of hip replacement. After a week of hospitalization he has been catheterized for incontinence but within next week he becomes unwell and fever has occurred. A specimen of urine was sent for culture. Your task: 1. Plate urine sample from your patient using calibrated loops: a) small loop – one half of MacConkey agar and blood agar b) big loop – one half of MacConkey agar and blood agar Label plate with your initials and incubate 24 h at 37° C. 2. Estimate growth (how many bacterial species is growing on culture media) and what is the number of bacterial colonies (count bacterial colonies), and record results: a) number of bacterial species ------------------------------------------------------------ b) number of bacterial colonies ----------------------------------------------------------- How bacteria isolated from patient’s urine sample may be indentified to species?

a) Gram-staining-----------------------------------------------------------------------------

b) other tests (propose some) ------------------------------------------------------------ ----------------------------------------------------------------------------------------------- -----------------------------------------------------------------------------------------------

3. Which groups of antimicrobials may be used to treat UTI with the isolated microorganism taking into consideration the type and count of isolated organism? What mechanisms of resistance isolated species may present? ------------------------------------------------------------------------------------------------------------------------------ Amoxicillin – S Norfloxacin – S Cefuroxime – S ESBL - negative Trimetoprim – S


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CLINICAL CASES

Your patient is 16-days old boy with high fever and blond in urine. The suprapubic aspiration was done and the

Specimen was send to the lab where Klebsiella pneumoniae was cultured at 102CFU/ml.

Could the isolated bacterium be an etiologic agent of UTI

despite the low number of bacteria in urine? If so, why?

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Susceptibility testing:

• Amikacin – R

• Amoxicillin/clavulanic acid – I

• Cefotaxime – S

• Ceftazidime – S

• Gentamycin – R

• Imipenem – S

• Meropenem – S

• Piperacillin/tazobactam – S

Case 1

Answer questions

Which antimicrobials should be chosen for

treatment? (take into consideration the age of

patient)

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Name mechanisms of resistance to antimicrobials that isolated

bacterial strain may produce

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Your patient is 63-years old men with urinary catheter hospitalized in ICU who developed high fever and blood has

occurred in the urine bag. The urine sample obtained from the catheter was send to the lab where E. coli ESBL+ was

cultured at 105 CFU/ml.

Could the isolated bacterium be an etiologic agent of UTI

despite the low number of bacteria in urine? If so, why?

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Susceptibility testing:

Case 2

Answer questions

Which antimicrobials should be chosen for

treatment? (take into consideration the age of

patient)

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Name mechanisms of resistance to antimicrobials that isolated

bacterial strain may produce

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•Amikacin – S•Ampicillin/sulbactam - I•Cefotaxime – R•Ceftazidime – S•Gentamycin – S•Imipenem – S•Meropenem – S•Ertapenem – S •Amoxicillin/clavulanic acid – I•Piperacillin/tazobactam – S •Cotrimoxazole – R


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Your patient is 34-years old woman with clinical symptoms of urinary tract infection. She delivered voided urine

sample to the lab where E. coli was cultured at 103 CFU/ml. However, the Gold test was positive.

Interpret the result. Should the infection be treated with antimicrobials despite low number of bacteria in urine? If so, propose some antimicrobials.

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Case 3

Answer questions

Case 4

Your patient is 3-months old baby girl with clinical symptoms of urinary tract infection. Mother of the child delivered voided urine sample collected to the urine bag to the lab where the following bacteria were isolated:E. coli 103 CFU/mlEnterococcus faecalis 102 CFU/mlStaphylococcus epidermidis 104 CFU/ml Answer questions

Interpret the result. Should the infection be treated with antimicrobials? If so, propose some antimicrobials.

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Student notes

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Issues to be discussed during class

1. Why community-acquired, but not nosocomial UTI may be treated empirically? --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

2. When urine sample culture and urinalysis are necessary and when are usually omitted? --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

3. Why E. coli is most common etiologic agent of UTI? What are factors predisposing this species to cause UTIs?

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4. Why urine alkalization predisposes to UTI and CA-UTI? --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

5. Why catheterization predisposes to UTI? --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

6. Why serology is not used to diagnose UTI?

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7. Why Proteus mirabilis is an important pathogen of CA-UTI? --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

8. Why there is no need to treat CA-ASB? --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

9. Why diabetes and/or neutropenia predisposes to UTIs?

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SELF-ASSESMENT

1. Give the definition of bacteriuria, pyuria , sterile pyuria hematuria, dysuria, dyspareunia,

reinfection and recurrency (relapse).

2. Give the definition of UTI syndromes and they typical presentation (urethritis, cystitis,

pyelonephritis, prostatitis, urosepsis, asymptomatic bacteriuria, catheter related UTI).

3. What are the reservoirs and routes of transmission of UTI.

4. Host defenses against UTI.

5. Name groups of risk for UTI .

6. What are factors predisposing to urinary tract infections.

7. Name antimicrobials used for treatment of urinary tract infection . Name groups of antibiotics,

representatives of groups, mechanism of action, mechanisms of bacterial resistance to that

antimicrobials ( if exist).

8. Means of prevention of UTI and its recurrences.

9. Name microorganisms that are responsible for UTI.

10. Name most important virulence factors of main pathogens causing of UTI and they role in

pathogenesis of UTI .

11. What microorganisms may cause sterile pyuria.

12. Specimen collection and handling in UTI.

13. Name and describe laboratory tests used for diagnosis of UTI.

14. Adventages and disadventages of dipstick tests in UTI.

15. What is interpretation of urine culture result (depending on urine sample).

16. Name three most common organisms causing cystitis/prostatitis:

17. Name most common organisms causing pyelonephritis:

18. Fungi are rare etiologic agents of UTI, but some groups of patients are especially susceptible to

these infections – which groups of patients?

19. Give examples of GP cocci causing UTIs:

20. Give examples of GN rods fermentative and nonfermentative causing UTIs:

21. Name viruses causing UTIs

22. Explain term asymptomatic bacteriuria:

23. In microscopic examination of urine specimen how many bacterial cells per oil immersion field

correlates with bacterial count indicative of UTI?

24. How many bacterial species may produce UTI simultaneously?

25. Bacterial count indicative of UTI

a) in voided urine sample is ------------------ b) in urine sample from catheter is ------------------ c) in urine sample obtained via suprapubic aspiration is ------------------

26. False-positive nitrite test may results from: 27. Which bacteria causing UTIs will give negative nitrite test results and why? 28. Leukocyte esterase indicates in urine the presence of.... 29. What is the number of white blood cells per milliliter of urine in pyuria? 30. Interpret the following results of urinalysis:

a) pyuria-positive but culture-negative b) culture-positive but pyuria-negative c) pyuria-negative but culture-positive polymicrobic d) pyuria-negative and culture-positive

31. How long urine specimen may sit at RT before transport?


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32. During what period of time urine sample should be plated onto culture media in lab to obtain relable results?

33. When culture of urine specimen may be negative despite existing symptoms of infection and positive pyuria?

34. The major determinant for development of bacteriuria in catheterized patients is..... 35. Explain terms: urinalysis, bacteriuria, pyuria, asymptomatic bacteriuria, urosepsis. 36. Name microorganisms of urethral flora in men and women. 37. What species of obligatory anaerobic bacteria may cause UTIs? When they may be suspected as

etiologic agents of UTIs? 38. When cases of CA-UTI should be screened for and treated? 39. What is the Gold test for? 40. What are rapid tests used to diagnose UTIs? 41. What does sterile pyuria means? 42. Name groups of antimicrobials used to treat UTIs?

Remember! To get credit of class all materials must be supplemented! Credit of class ------------------------------------ (teacher’s signature) Date -------------------------------------------------


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SUPPLEMENTARY MATERIALS Collection of urine samples:

1. Clean catch midstream urine, voided urine specimen or specimen collected during the middle of voiding (midstream urine specimen).

The clean-catch is the most common type of urine specimen. The technique involved in collection is based on discarding the first portion of urine. The first voided specimen should be discarded since the initial urine flushes urethral contaminants. It is the second, midstream sample that should be sent to the laboratory. First, the urethral area should be cleaned with an antiseptic cloth and then the midstream urine sample should be collected into a sterile container. It is recommended that the first voided morning specimen be collected so bacteria will have multiplied to high levels after overnight incubation in the bladder. If this is not possible, the urine should be allowed to incubate in the bladder as long as possible before collection.

2. Indwelling catheter or Foley catheter

Catheterized specimens are indicated in certain situations, such as patients who are unable to provide clean-catch specimens because of urologic or neurologic problems including impaired consciousness. Hospitalized patients who have indwelling catheters are especially at risk for developing UTI. To avoid contamination, urine sample should be drawn in a sterile fashion (after disinfection with alcohol) from either the catheter itself or through the port designed specifically for this purpose, NOT from the urine collection bag. Specimen collection is critical since colonization of the bag or actual catheter is common.

3. Suprapubic Aspirate

The suprapubic aspirate technique avoids urethral contamination but is invasive and is seldom used in today's practice. It is usually reserved for infants, from whom it is difficult to obtain clean, reliable urine specimens. In this procedure, the skin above the bladder is disinfected and sterile needle with syringe are plunged into the bladder. Urine is aspirated and placed into a sterile container.

4. Collection of urine by use of a single catheter (straight catheter technique) is the next-best technique for obtaining urine specimens

with minimal contamination, but is not indicated clinically in most patients as is invasive and the possibility to introduce bacteria into the bladder, and some complications have been reported. URICULT for rapid analysis The Uricult is designed for UTI screening by providing a semi-quantitative colony count along with a presumptive identification of many common uropathogens. The product consists of a two sided paddle containing selective and non-selective media that fits securely into a screw cap plastic vial to maintain sterility. One side contains agar that changes color in the presence of various organisms including E. coli, Proteus, Pseudomonas, Enterobacter, and others. The opposite side contains EMB (Eosin Methylene Blue) agar, a selective medium that will support the growth of most Gram negative organisms while providing additional information regarding the suspected pathogen.


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To test a sample, the Uricult dip paddle is removed from it’s protective vial, immersed into the urine sample, and returned to the vial for incubation at 37° C for 18-24 hours. Smaller samples can be dispensed directly onto the media using a syringe or sterile pipette. Following incubation, the results are compared to a color chart for presumptive identification and colony count. The entire vial can then be sent off for confirmation and antibiotic susceptibility testing.

After incubation at 37° C

UNUSUAL ETIOLOGIC AGENTS OF UTI

Viruses are uncommon cause of UTIs in an immunocompetent host but they are increasingly

recognized as the cause of lower UTIs – mainly hemorrhagic cystitis in immunocompromised patients.

BK virus (polymoa virus), adenoviruses and CMV are predominant pathogens involved in hemorrhagic

cystitis after seam cells and solid organs transplantation.

Diagnosis is based on molecular techniques (NAATs).

Treatment – cidofovir (nucleotide analog) active against many DNA viruses e.g. adenoviruses, herpes viruses, polyomaviruses, papillomaviruses and poxviruses. It is also active against mutant acyclovir- and gancyclovir-resistant HSV and CMV.

Unusual UTIs causes – rarely encountered

Corynebacterium urealyticum – commensal skin organism; strongly urease-positive (alkalizes the

urine) and slowly-growing (need 48-72 hours on lab media to appear – so may be overlooked). It is

typically resistant to most antibiotics except vancomycin and fluoroquinolones. C. urealyticum most

commonly cause UTIs in hospitalized catheterized patients.

Haemophilus influenzae/parainfluenzae – cause UTIs in children (do not grow on standard urine

culture media) – mostly in children with abnormalities or dysfunction of UTIs.


19

Candida spp. cause candiduria or funguria. Risk factors: invasive devices, broad spectrum antibiotic therapy, immunosupression, parenteral nutrition. Hematuria is common, but most patients with candiduria are asymptomatic. Renal candidiosis is usually spread hematogenously and commonly originates from gastrointestinal tract. Affects most commonly diabetic patients, cancer patients, immunocompromised, AIDS patients, patients on chemotherapy. Therapy – only if patient will undergo urologic manipulation, is symptomatic, is neutropenic or is recipient of renal allograft. Azoles (e.g. fluconazole, clotrimazole, miconazole - if resistant amphotericin B) Complication: emphysematous (presence of gas in bladder wall) cystitis or pyelonephritis. Mycobacterium tuberculosis - patients with urinary tract tuberculosis can present with dysuria and hematuria, though many patients are asymptomatic, with only sterile pyuria, with or without microscopic hematuria. The kidney is usually infected by hematogenous spread of bacilli from a focus of infection in the lungs and/ or bowel. Tuberculous ureteritis is always an extension of the diseases from the kidney. Bladder lesions are without exception secondary to renal TB. Tuberculosis of the urinary tract is easily overlooked. Symptoms that sometimes occur include back, flank and suprapubic pain, hematuria, frequency, and nocturia. These might also suggest conventional bacterial urinary tract infection. Symptoms typical of tuberculosis such as fever, weight loss, and night sweats also are unusual. Urogenital tuberculosis may cause complications, such as ureteral strictures, oligospermia in men, and vaginal bleeding in women. The genitourinary tract is the most common site of extra-pulmonary tuberculosis. The incidence of tuberculosis is rising, particularly due to HIV infection. Genitourinary tuberculosis has been reported in 8-10% of all cases in developed countries and in 20% in third world countries.

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