Quick facts
- United States: an automated colony counter is a named entry — 21 CFR 866.2170 — and sits in Class I.
- United States: a manual colony counter is a separate named entry at 21 CFR 866.2180, also in Class I, so the two are kept apart by automation rather than by class.
- Canada: there is no named colony-counter entry; the instrument is an in vitro diagnostic device and its class comes from the rules in Part 2.
- Canada: the short table in Rule 9 places an IVDD used to identify or infer the identity of a cultured microorganism in Class I.
- Canada: the default rule places any IVDD not reached by the other rules in Class I, and Rule 7 lifts a device to the class of a higher-risk device it is used with.
- Canada: the regulation text cited here is current to 2026-09-21 and was last amended on 2026-06-17.
A plate reading looks the same on both sides of the border, but the two systems behind the counter do not file it the same way. One splits the instrument by how it counts; the other names no counter at all and reaches a class from what the count is used for. For a laboratory buyer, that split decides what the instrument's file carries and what changes when the counter is bundled with an identification system.
What does a colony counter do?
It counts the colonies on a culture plate, and it exists to turn a visual estimate into a number that can be recorded and compared.
The instrument is a laboratory device that supports microbiology. A plate is placed under a lens or a camera, the colonies are counted by eye or by image analysis, and the result is written into the bench record. The count itself is not a diagnosis; it is a measurement that a microbiologist reads against a specification or a reference, and it is used to judge whether a sample, a surface or a batch of media meets a limit.
That supporting role is what the two systems describe differently. One treats the instrument as a device in its own right; the other treats it as part of the microbiology workflow it serves.
| Item | Canada | United States |
|---|---|---|
| How the counter is described | By rule, as an IVDD | Named entries at 866.2170 and 866.2180 |
| Class for a manual counter | Class I under the microbiological identification entry | Class I |
| Class for an automated counter | Class I under the microbiological identification entry | Class I |
| What a filing cites | The rule and the use | The device entry and product code |
Why does the United States have two entries for a colony counter?
Because the country names the automated counter and the manual counter separately, and it keeps them in the same class while separating the entries.
21 CFR 866.2170 covers an automated colony counter and places it in Class I, filed under a product code for the automated instrument. 21 CFR 866.2180 covers a manual colony counter and places it in Class I under its own code. The split is about the method, not about risk: an instrument that counts by image analysis and an instrument that counts under a magnifier are the same class and different entries.
What this means for a buyer is that the American file changes when the method changes, even though the class does not. A laboratory that replaces a manual counter with an automated one is filing against a different entry.
| Counter type | US entry | US code | US class | Canadian basis | Canadian class |
|---|---|---|---|---|---|
| Automated colony counter | 21 CFR 866.2170 | KZB | Class I | Rule 9, microbiological identity | Class I |
| Manual colony counter | 21 CFR 866.2180 | KZC | Class I | Rule 9, microbiological identity | Class I |
| Counter used with an identification system | Same entries | Same codes | Class I | Rule 7, higher-risk device | Class II or III |
How do Canada and the United States classify a colony counter?
It reaches a class from the rules, and the counter is classed by the job it does rather than by the method it uses.
A colony counter is an in vitro diagnostic device because it is used in vitro to examine specimens taken from the body and the surfaces around them. The short table in Rule 9 places an IVDD used to identify or infer the identity of a cultured microorganism in Class I, and the default rule places any IVDD not reached by the other rules in Class I as well. A counter that supports a microbiological count is inside that territory.
The method — manual or automated — does not appear in the Canadian rules at all. A laboratory that changes from a manual counter to an automated one is not changing the rule that applies, even though the American file would change.
Do Canada and the United States reach the same class by different routes?
They can reach the same class by different routes, and the routes part company as soon as the counter is bundled with something else.
In the United States the counter stays in its own entry, and the entry is Class I whatever else sits beside it on the bench. In Canada the counter is read against the combined-device rule as well. Where an IVDD, including its analyzers, reagents and software, is intended to be used with another IVDD, the class of both is the class of the higher-risk device. A counter wired to an identification system that carries a higher class therefore carries that higher class with it.
This is the point most often missed when a laboratory buys a counting station as a package. The specifications describe the counter; they do not describe the system it is joined to, and in Canada the joined system is part of the class.
Does a colony counter change class when it is bundled with an identification system?
In Canada it does, and in the United States it does not. The combined-device rule is what makes the difference.
A counter that is used with an identification system is read against the higher-risk device in Canada, so the class follows the system rather than the counter. The same counter used on its own stays in the lower class. A laboratory that shares one count station between a general bench and an identification bench has two classification premises for one instrument, and the intended use is what separates them.
In the United States the counter keeps its own entry, and the entry does not absorb the class of the system beside it. A buyer comparing the two countries therefore has to read the class in Canada from the bench layout and in the United States from the entry.
Which consumables does a microbiology bench restock?
A plate-reading station runs on the sample and plate-handling lines that surround the counter. The sterile graduated specimen cups carry the sample to the bench, and the 120 mL sterile screw-cap container holds a specimen that has to be kept before it is plated. For a laboratory that also runs its own sterilisation cycle, the sterilization monitoring collection pairs with the 24-hour monitoring five-pack trial. For clinics and multi-site groups buying at case level, the wholesale ordering page sets out account and case terms, and the B2B wholesale collection lists the lines held for institutional buyers. Reselling? become a distributor.
Sources
- 21 CFR 866.2170, automated colony counter
- 21 CFR 866.2180, manual colony counter
- 21 CFR 866.2320, differential culture medium
- 21 CFR 866.2390, transport culture medium
- 21 CFR 866.2900, microbiological specimen collection and transport device
- 21 CFR 866.3920, assayed quality control material for clinical microbiology assays
- Medical Devices Regulations, SOR/98-282
- ISO 15189:2022, medical laboratories
- ISO 13485:2016, medical device quality management
- ISO 14971:2019, risk management of medical devices
- ISO 11133:2014, culture media
- IEC 61010-1:2010, safety of electrical measuring equipment
- openFDA device classification API
- CLSI, clinical and laboratory standards
- Public Health Ontario, laboratory services test index
- CCOHS, OSH answers
- College of Optometrists of Ontario, standards of practice
- Opto, eye health library
- American Academy of Ophthalmology, dry eye
- Canadian Dental Association
A plate-reading bench whose record is missing is a bench that cannot answer a question about the last count. The printable plate reading log is a free sheet with columns for the plate, the media lot, the count, the operator and the date, so a result is written down rather than remembered. The plate reading log generator built for a microbiology bench sizes the sheet to the number of stations a laboratory runs. No account and no sign-up are needed to open either one.
Ordering microbiology consumables for a teaching lab or a small clinic? See the wholesale ordering page.
Related reading
- Petri Dishes 100 x 15 mm: Canadian Lab Ordering Checklist
- Agar Petri Dishes: Agar Types, Prepared Plates and Storage
- Histology Cassettes and Microtome Blades: Canada vs the US
CliniEco Medical supplies laboratory, eye care and dental consumables of the kind described in this article. MDEL #35334. This article is written for optometry, laboratory and procurement professionals and is not legal advice; the class of an instrument and the records kept by a laboratory belong to the laboratory and to the requirements that apply to it.
Frequently Asked Questions
Is a colony counter a Class I device in the United States?
Yes. An automated colony counter is Class I under 21 CFR 866.2170 and a manual colony counter is Class I under 21 CFR 866.2180, so both are Class I and they are separated by entry rather than by class.
Why are there two American entries for a colony counter?
Because the automated counter and the manual counter are described and filed separately. The split reflects the counting method, not a difference in class.
Does Canada name a colony counter?
No. The Canadian schedule names very few devices, and a colony counter is not one of them. It is an in vitro diagnostic device, and its class is reached from the rules in Part 2.
How does Canada reach Class I for a colony counter?
The short table in Rule 9 places an IVDD used to identify or infer the identity of a cultured microorganism in Class I, and the default rule also places any IVDD not reached by the other rules in Class I.
What changes the class when a counter is bundled with an identification system?
In Canada, Rule 7 gives the counter and the system the class of the higher-risk device, so the counter can move up. In the United States the counter keeps its own entry and its own class.
What should a plate reading record carry?
The plate identification, the media lot, the count, the operator and the date. In Canada the record should also name the system the counter is joined to, because the class can rest on that system.
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