Prolex™ E. coli O157 — Presumptive Serogroup ID From a Single SMAC Colony in 2 Minutes
Wet-latex agglutination for clinical microbiology, public-health, and food-safety labs running stool-culture STEC workups. Positive + Negative Controls included in every kit. Reduced E. hermanii cross-reactivity. Independently validated by the CDC at 100% sensitivity and 100% specificity (Sowers 1996).
Pack Sizes & Sub-SKUs
PL.070B
50 tests · $196.71
PL.071B
100 tests · $282.24
Positive + Negative Control Latex included in every kit.
2 min
SMAC read
100/100
Sens / Spec (CDC)
CE+UKCA
Marked IVD
Read Window
From a single non-sorbitol-fermenting colony on Sorbitol MacConkey Agar. Positive (visible blue-latex agglutination) read against the Negative Control Latex on the same card.
CDC Sensitivity / Specificity
CDC-led independent evaluation across 159 strains, alongside Oxoid and Remel — all three at 100/100 (Sowers EG et al., J Clin Microbiol 1996; PMID 8727921).
IFU Clinical Sensitivity
Manufacturer's clinical evaluation in patients with diarrhoea, haemorrhagic colitis, or HUS. 100% sensitivity per the IFU performance section.
Latex Reagents Aren't All The Same Read
Every clinical micro lab running STEC workups already does the upstream work: Sorbitol MacConkey Agar (SMAC), pick the non-sorbitol-fermenting colonies, run a Shiga toxin EIA or NAAT. The serogroup confirmation step is where the latex kit matters — and where the differences between kits actually show up at the bench.
The Prolex™ E. coli O157 kit was specifically formulated to reduce common cross-reactions with other 'O' and 'H' antigens — in particular Escherichia hermanii, which is a known false-positive risk on competing latex products. The kit includes both the Positive Control (heat-inactivated E. coli O157:H7 antigen) and a separate Negative Control Latex (rabbit IgG that does NOT react with O157), so every positive isolate gets a built-in non-specific-agglutination check on the same card. No separate purchase. No budget surprise.
"This unique reagent has been developed to remove common cross reactions with other 'O' and 'H' antigens, in particular E. hermanii."
— Prolex™ E. coli O157 IFU §"PRINCIPLE" (Rev. 2025-09)
Sowers 1996 — The CDC Head-to-Head
Sowers EG, Wells JG, Strockbine NA. J Clin Microbiol 1996 May;34(5):1286–1289 (PMID 8727921). 159 strains. Prolex: 100% sensitivity, 100% specificity vs. CDC reference antiserum.
Chan 1998 — Head-to-Head Specificity
Chan E, Ball L, Horsman GB. Clin Lab Sci 1998 Sep–Oct;11(5):266–268 (PMID 10186949). Wellcolex 100/99, RIM 100/99, Prolex 99/100, Oxoid 100/100. Best specificity in the set.
Controls In The Kit
Positive Control (PL.074B/PL.075B — heat-inactivated E. coli O157:H7 antigen) + Negative Control Latex (PL.076B/PL.077B — non-reactive rabbit IgG) included. Daily QC per IFU §"QUALITY CONTROL", no separate SKU.
Wet Latex, Visible Read
Blue polystyrene latex gives clearer visible agglutination than dry-spot competitors at borderline reactions — fewer "is that a positive?" repeats on the bench.
7 Steps. 2 Minutes. Same-Day Presumptive Serogroup.
From a non-sorbitol-fermenting colony on SMAC to a presumptive O157 read at the bench. Every step is from the current IFU (Rev. 2025-09).
Reagents to Room Temp
Bring the O157 Latex Reagent, Positive Control, and Negative Control Latex to room temperature.
Inspect for Autoagglutination
Re-suspend the latex by gently inverting. Per IFU: do not use if particles fail to re-suspend.
Make a 3–5 McFarland Suspension
0.2 mL saline (0.85%) or PBS in a 12 × 75 mm tube. Pick non-sorbitol-fermenting colonies from SMAC to a 3–5 McFarland Standard.
QC the Kit (Daily)
Test the Latex Reagent + the Negative Control Latex against the Positive Control before running test isolates.
Mix on the Test Card
One drop of latex reagent + one drop of test suspension on the card. Mix with the stick provided.
Rock and Read Within 2 Min
Rock the card gently for up to 2 minutes. Visible blue-latex agglutination = presumptive O157. Reading after 2 minutes is invalid.
Confirm Against Negative Control
Mandatory secondary step on every positive — IFU §"INTERPRETATION OF RESULTS". If both agglutinate, result is inconclusive; confirm biochemically.
Full Procedure In The IFU
Download the current IFU (PL.070B-PL.071B-IFU-2025-09) for complete procedure, limitations, and quality control requirements.
Download PDF downloadThe Right Fit for Every Lab Role
Same Chemistry The CDC Validated. Direct Pricing.
Independent CDC head-to-head (Sowers 1996) put Prolex, Wellcolex, and Oxoid at 100/100 — feature-parity on chemistry. The differences are logistics and packaging. PL.070B / PL.071B ships factory-direct from Georgetown, TX. Positive + Negative Controls are part of the kit. Same SOP your bench MTs already know if they run any wet-latex serotyping.
- check_circleIndependent CDC validation: 100% sens / 100% spec (Sowers 1996, n=159)
- check_circlePositive + Negative Control Latex included — no separate budget line
- check_circleCE + UKCA Marked IVD, ISO 13485 — CAP/CLIA documentation ready
- check_circlePair with PL.1070 Non-O157 STEC kit for the full Big 6 panel from one vendor
Cost-Per-Test Math
Direct factory pricing — no distributor markup.
Submitting-Lab Triage. Confirmed Pipeline Stays Intact.
Latex agglutination is upstream of WGS / PFGE — not a replacement. Prolex™ O157 gives submitting and reference labs a same-day presumptive serogroup at the bench so the case file opens before culture-and-confirm finishes. Sowers et al. (CDC) is the canonical independent validation; standardizing on Prolex gives your contributing labs reproducible results across a multi-jurisdiction submission.
- check_circle2-minute presumptive serogroup ID at the submitting lab
- check_circleSame chemistry as the leading O157 latex kits (CDC head-to-head: 100/100)
- check_circleReduced E. hermanii cross-reactivity — fewer false-positive walk-backs
- check_circleWet-latex format gives clearer reads than dry-spot for borderline isolates
Independent Peer-Review
Wet-Latex Confirmation. Sub-0.1% Azide. No Hazmat.
For food-safety labs running FDA BAM Chapter 4A workflows, the O157 latex confirmation step is where read-clarity matters most. Wet-latex agglutination shows clear visible clumping; dry-spot can be ambiguous at borderline reactions. Sodium azide preservative is sub-0.1% — no Hazmat surcharge, no DOT regulatory paperwork. Cold chain is overnight from Georgetown, TX.
- check_circleWet-latex format for clearer borderline reads vs. dry-spot competitors
- check_circleSub-0.1% sodium azide preservative — non-Hazmat shipping classification
- check_circleTwo pack sizes for varying lab throughput (50T or 100T)
- check_circleISO 13485 manufacturer — FSMA documentation file ready
FDA BAM Chapter 4A Context
FDA BAM Chapter 4A covers the laboratory examination of foods for diarrheagenic Escherichia coli, including O157:H7. This kit provides serogroup-level latex agglutination downstream of Shiga toxin EIA / PCR screens. Confirmatory testing (biochemical or molecular) per the BAM protocol is still required for regulatory reporting.
Per IFU §"LIMITATIONS": positive results should be confirmed using routine biochemical testing.
Factory Direct. Net 30. The Only US Source For The Full STEC Panel.
Most US labs sourcing the full STEC workflow split it across two manufacturers — Oxoid or Remel for O157, individual antisera or a separate kit for the Big 6 non-O157 STEC. Pro-Lab Direct is the only US source where the O157 kit (PL.070B / PL.071B) and the Big 6 Non-O157 STEC kit (PL.1070) come from the same manufacturer, on the same PO, in the same cold-chain shipment.
- check_circleSingle SKU per pack size; controls included
- check_circleNet 30 available for qualifying institutions
- check_circleVolume pricing on request — contact for institutional quote
- check_circlePair with PL.1070 (Non-O157 STEC) for one-vendor STEC panel
Single-Vendor STEC Panel
Order Prolex™ E. coli O157 Direct
Two pack sizes — same chemistry, same IFU. Pair with the Non-O157 Big 6 kit for the complete STEC panel from one vendor.
Prolex™ E. coli O157 Latex Kit
50-test kit sized for typical clinical micro lab volumes. Positive + Negative Control Latex included.
Prolex™ E. coli O157 Latex Kit (100T)
Same chemistry, same IFU — 100-test pack for higher-volume reference and food-safety labs.
Prolex™ Non-O157 STEC Kit
USDA Big 6 (O26, O45, O103, O111, O121, O145) — same Prolex platform, same vendor, complete STEC panel.
Prolex™ O157 vs. Other Latex Methods
All three major US latex kits show feature-parity on chemistry per CDC head-to-head. Differentiation is in kit composition, read clarity, vendor consolidation, and direct pricing.
| Feature | Prolex™ PL.070B / PL.071B | Oxoid DrySpot DR0120M | Remel Wellcolex | Reference Lab |
|---|---|---|---|---|
| Read Window | within 2 min | within 1 min (dry-spot) | within 2 min | 1–3 days |
| Format | check_circleWet latex (visible agglutination) | Dry latex on cards | Wet latex (red) | Send-out |
| Storage | 2–8 °C | 2–25 °C (room temp) | 2–8 °C | N/A |
| Controls Included | check_circleYes — Pos + Neg Control Latex | Not separately enumerated | Sold separately | N/A |
| E. hermanii-Tuned Chemistry | check_circleYes (per IFU) | Not specifically claimed | Not specifically claimed | N/A |
| CDC Head-to-Head (n=159) | 100/100 (Sowers 1996) | 100/100 (same study) | 100/100 (same study) | N/A |
| Pack Sizes | check_circle50 (PL.070B) or 100 (PL.071B) | 120 tests | (varies) | N/A |
| Same-Vendor Big 6 Kit | check_circleYes — PL.1070 | No equivalent | No equivalent | N/A |
| Factory Direct | check_circleYes (Pro-Lab Direct) | Distributor only | Distributor only | N/A |
People Also Purchased
Frequently ordered together in clinical, public-health, and food-safety microbiology labs running STEC workups.
PL.1070
Prolex™ Non-O157 STEC Kit
USDA Big 6 serogroups (O26, O45, O103, O111, O121, O145) in one kit. Pair with O157 for the complete STEC panel from one vendor.
View PL.1070 →
Pro-Lab
McFarland Standards (3.0 / 4.0 / 5.0)
Required for the 3–5 McFarland turbidity match in step 4 of the O157 procedure. Pro-Lab Pro-McFarland line.
View McFarland →
PLD001 / PLD010
Pro-Loops™ Calibrated Inoculation Loops
Sterile single-use plastic loops for picking non-sorbitol-fermenting colonies from SMAC for the suspension prep step.
View Pro-Loops™ →Technical Specifications
PL.070B and PL.071B share the same chemistry, IFU, and procedure — only the pack size differs.
Documents
Current IFU (Rev. 2025-09) is hosted in this product directory. SDS available on request — submit a quote with the document name in the notes field.
Frequently Asked Questions
What does the Prolex™ E. coli O157 kit identify?
It identifies the E. coli O157 somatic (LPS) antigen by latex agglutination. It detects any non-sorbitol-fermenting E. coli O157 strain regardless of H-type — so O157:H7, O157:H16, etc. all give a positive read. The IFU is explicit on this point: "Some other E. coli O157 strains (e.g., O157:H16) that are non-sorbitol-fermenting also produce a positive result with this test." Definitive H-typing requires reference-lab serotyping.
How long does the read take?
Up to 2 minutes at room temperature, from a single non-sorbitol-fermenting colony on Sorbitol MacConkey Agar (SMAC) suspended to 3–5 McFarland in saline or PBS. Reading after 2 minutes is invalid — drying-related artifact may be misread as agglutination.
Are positive and negative controls included?
Yes. The kit includes both a Positive Control (PL.074B/PL.075B — heat-inactivated E. coli O157:H7 antigen suspension) and a Negative Control Latex Reagent (PL.076B/PL.077B — rabbit IgG that does NOT react with O157). Per the IFU §"QUALITY CONTROL", the Latex Reagent and the Negative Control Latex must both be tested against the Positive Control before running test isolates each day.
How does this kit handle E. hermanii cross-reactivity?
The IFU §"PRINCIPLE" states the latex was "developed to remove common cross reactions with other 'O' and 'H' antigens, in particular E. hermanii." Per IFU §"LIMITATIONS" #4: "rare strains can cross-react." Independent head-to-head (Chan E et al., Clin Lab Sci 1998) reported 100% specificity for Prolex — best of four kits tested.
Has the kit been independently validated?
Yes. Sowers EG, Wells JG, Strockbine NA. "Evaluation of commercial latex reagents for identification of O157 and H7 antigens of Escherichia coli." J Clin Microbiol. 1996 May;34(5):1286–1289 (PMID 8727921). The CDC-authored study evaluated Prolex against a 159-strain reference panel and reported 100% sensitivity, 100% specificity. A second independent study (Chan 1998, PMID 10186949) reported 99% sensitivity, 100% specificity in head-to-head against Wellcolex, RIM, and Oxoid.
Is the kit CE Marked? Is it FDA cleared?
The current IFU (Rev. 2025-09) carries both the CE Marked IVD (Σ) and UKCA marks. Pro-Lab Diagnostics is ISO 13485 certified. FDA 510(k) status is not currently displayed on the IFU. Fisher Scientific lists the kit at CLIA Complexity "Non-waived" (Moderate or High Complexity), which is a regulatory recognition for clinical use but does not by itself confirm an FDA 510(k) clearance. Confirm regulatory status with Pro-Lab US ops before specifying for FDA-regulated workflows.
What is the difference between PL.070B and PL.071B?
Same chemistry, same IFU, same procedure — different pack size. PL.070B is 50 tests ($196.71, ~$3.93 per test). PL.071B is 100 tests ($282.24, ~$2.82 per test). Reference labs and food-safety labs typically order PL.071B; clinical micro labs typically order PL.070B.
Can I pair this with the Prolex™ Non-O157 STEC kit?
Yes. Pro-Lab Direct is the only US manufacturer that offers the full STEC serogroup panel from one source: Prolex™ E. coli O157 (PL.070B / PL.071B) plus Prolex™ Non-O157 STEC (PL.1070) covering the USDA Big 6 (O26, O45, O103, O111, O121, O145). Same latex platform, same vendor, same cold-chain shipment.
Why does the kit require 2–8 °C storage when Oxoid DrySpot doesn't?
Wet-latex agglutination chemistry — used by Prolex, Remel Wellcolex, and most other latex serogrouping kits — requires cold storage to maintain antibody-coated latex stability. Dry-spot competitors (Oxoid DrySpot) trade some read clarity for room-temperature stability. For most clinical labs the cold-storage requirement is parity with the rest of the latex panel (Lancefield strep, staph, Salmonella, Shigella).
What materials do I need that aren't in the kit?
Per the IFU §"MATERIALS REQUIRED BUT NOT PROVIDED": (1) Normal saline (0.85% NaCl) or Phosphate Buffered Saline (PBS), (2) McFarland Standard 3.0, 4.0, or 5.0, (3) 12 × 75 mm test tubes, (4) Inoculating loop or needle, (5) Pasteur pipettes, (6) Sorbitol MacConkey Agar (SMAC) plates. Pro-Lab also stocks McFarland Standards, Pro-Loops, and Pro-Tips for the workflow.
Order The Prolex™ E. coli O157 Kit Direct.
PL.070B (50 tests · $196.71) and PL.071B (100 tests · $282.24) ship cold from Georgetown, TX. CE + UKCA Marked IVD. ISO 13485 manufacturer. Pair with PL.1070 Non-O157 STEC for the complete Big 6 + O157 panel from one vendor.
Ships cold from Georgetown, Texas · CE + UKCA Marked IVD · ISO 13485