Urology and Dipslides

These UTI testing dipslides feature two different agars (culture medium). One side of the slide has CLED agar (green side) which tests for / supports the growth of urinary pathogens. This agar will show the total viable bacterial count. If you count the number of colonies on the CLED agar and compare it with the chart, it will indicate whether an infection is present based on the appropriate cfu/ml threshold. Colonies on this agar are fairly simple to differentiate. Growth characteristics can be viewed in the list of urinary pathogens in the list further down the page.

The red side (MacConkey agar) grows / tests for coliforms. Differentiates between coliforms and non lactose fermenters. Gram positive are inhibited. Salmonella and shigella species appear as straw colonies. Coliforms appear as red / pink colonies with bile precipitation.

The listing price is for one box of dipslides. Each box contains 10 slides.

How are dipslides used to test for Urinary Tract Infections?

Dipslides are a simple and effective way of testing urine for evidence of urinary tract infections. Testing with the dipslide is easy as you just dip the slide into a mid stream sample of urine for approximately 10 seconds and then allow the dipslide to drain to remove any excess fluid. After the dipslide is used and placed within its container, the patient's details can be added on to the label provided.

Dipslides are accompanied by a comparison chart. Using the chart, colonies are counted using colony forming units (cfu) per ml. 10⁵ cfu per ml (on CLED agar) resulting from a urine sample tested using a dipslide, indicates a urinary tract infection.¹

Although the 10⁵ cfu / ml threshold is recognised as indicative of UTI, lower colony counts could also indicate urinary infection depending on different factors (male or female, catheter samples, symptomatic patients, single organism or mixed growth). As noted here in 'The Diagnosis of Urinary Tract Infection: A Systematic Review':

"Many laboratories define 105 colony forming units (cfu)/mL urine as the threshold. However, this threshold misses many relevant infections. There are therefore other recommendations that recommend the diagnosis of UTI from a count of 103 cfu/mL, depending on the types of bacteria detected."²

Guidelines by the appropriate health authority should be followed when deciding which threshold is diagnostic. Public Health England's publication on the diagnosis of urinary tract infections states that 'many labs use growth of 10⁴-10⁵ cfu/mL to indicate UTI' with lower counts indicating UTI in specific groups / circumstances. You can read the Public Health England document here: Public Health England UTI Document

CLED Agar supports growth of all urinary organisms that could potentially be pathogenic. It is also fairly easy to differentiate between colonies so that diagnosing the problem accurately is more likely. For example, on CLED medium, Staphylococcus aureus grows in deep yellow colonies whereas salmonella species grow in flat blue colonies. Urinary pathogens / bacteria that grow on CLED Agar:

Escherichia coli: Opaque yellow colonies, approx 1.25mm diam. More intense colour in the centre of the colony. Non-lactose fermenting strains - blue colonies.
Klebsiella species: Colour of colonies varies from yellow to white-blue, extremely mucoid.
Proteus species: Blue colonies, translucent. Colonies often smaller than Escherichia coli.
Salmonella species: Flat colonies, blue.
Pseudomonas aeruginosa: Matte green colonies with rough periphery.
Enterococcus faecalis: Small yellow colonies (0.5mm diam.).
Staphylococcus aureus: Intense yellow colonies, 0.75mm diam.
Coagulase negative staphylococci: White or pale yellow. Colonies are more opaque than Enterococcus faecalis.
Corynebacteria: Small grey colonies.
Lactobacilli⁴: Small grey colonies but with rougher surface than Corynebacteria.

Dipslides are cost effective and require no microbiology expertise to use. The dipslide can be easily used in the doctor's surgery and then sent on to the laboratory.

How to use CLED & MacConkey Agar slides to test urine

1. Collect a mid-steam sample in a sterile container.
2. Carefully place the dipslide in the urine sample. Make sure that both sides of the slide are completely covered.
3. After approx 10 seconds, remove the slide and allow to drain.
4. Replace the slide in its container and screw on the cap.
5. Incubate the dipslide for 16 - 24 hours at 37 degrees celsius.
6. Compare results with the chart provided.

Alternatively, the patient can urinate directly on to the slide (making sure that both sides are covered). This will need to be a mid stream specimen.

Step 1: Dip Test

For dip testing, immerse the Urine Test dipslide into the fluid for 10 seconds then remove and allow to drain for a few seconds.

Step 2 : Incubate Slide

Label the tube with the included stickers then place the slide into an incubator and allow to incubate.

Step 3 : Compare results

Count the amount of colonies that have grown on the slide and compare them to the comparison chart provided.

Urine infection test dipslide features

Flexible Paddle

Each dipslide features a virtually unbreakable and flexible paddle allowing for even, full surface testing.

Easy Run Off Design

Due to the design of the dipslide, fluids will drain off quickly during testing.

Recessed Handle

Each slide has a handle built into the lid that is recessed to help keep your fingers dry during testing.

Side Indicator

One side of the slide will have a circle indicator so you know which side was used for testing which type of contaminant.

Dual Sided

Each dipslide is dual sided to allow multiple contamination testing with one test.

Thick Reliable Agar

Each agar is thick (approx 4mm) and raised above the dipslide to allow for easy surface testing.

References:

1. http://www.urology-textbook.com/urine-culture.html
2. The Diagnosis of Urinary Tract Infection. A Systematic Review (2010),Guido Schmiemann, Dr. med., MPH, Eberhardt Kniehl, Dr. med., Klaus Gebhardt, Martha M Matejczyk, Dr. med.,and Eva Hummers-Pradier, Prof. Dr. med.
3. http://www.oxoid.com/uk/blue/prod_detail/prod_detail.asp?pr=CM0301&org=145&c=uk⟨=EN
4. The urine dipstick test useful to rule out infections. A meta-analysis of the accuracy (2004), Walter LJM Devillé, Joris C Yzermans, Nico P van Duijn, P Dick Bezemer, Daniëlle AWM van der Windt and Lex M Bouter

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