API and RAPID ID For Microbial Identification

By Acharya Tankeshwar •  Updated: 05/15/22 •  8 min read

BioMérieux’s API identification products are test kits for the identification of Gram-positive bacteria, Gram-negative bacteria, and yeast. The kits include strips that contain up to 20 miniature biochemical tests with a long shelf life.

API 20 E Test System

 It is one of the well-established methods for the identification of microorganisms up to the species level. The company runs APIWEB, where laboratories can input numerical profiles of the API strip results to obtain the organism identification. The software database enables reliable automated interpretation of API strip results which can be read on the screen and printed as per the need.

Identification System and Species Identified

Identification SystemSpecies Identification
API 20 EGram-negative bacilli
API 10 SGram-negative bacilli
Rapid 20EEnterobacteriaceae
API 20 NEGram-negative non-Enterobacteriaceae
API StaphStaphylococci
API 20 StrepStreptococci
API CandidaYeasts
API 20 C AUXYeasts
API 20 AAnaerobes
API CoryneCorynebacteria
API CampyCampylobacter
API ListeriaListeria
API NHNeisseria, Haemophilus
API 50 CHEEnterobacteriaceae
API 50 CHLLactic bacteria
API 50 CHBBacillus
ID 32 EGram-negative bacilli
Rapid ID 32 EEnterobacteriaceae
ID 32 GNGram-negative bacilli
ID 32 STAPHStaphylococci
Rapid ID 32 STREPStreptococci
ID 32 CYeasts
Rapid ID 32 AAnaerobes

API 20 A

The API 20 A system which consists of 20 microtubues containing dehydrated substrates, enables 21 tests to be carried out quickly and easily for the biochemical identification of anaerobes. Other tests such as colonial and microscopic morphology, Gram stain, etc. should be performed and the results are used to confirm or complete the identification.

These microtubes are inoculated with a bacterial suspension which reconstitutes the media. During incubation, metabolism produces color changes that are either spontaneous or revealed by the addition of reagents. The reactions are read according to the reading table and the identification is obtained by referring to the analytical profile index (API) or using the identification software.

API 20 E

API 20 E is a standardized identification system for Enterobacteriaceae and other non-fastidious, Gram-negative rods which uses 21 miniaturized biochemical tests and a database.

The API 20 E strip consists of 20 microtubes containing dehydrated substrates. These tests are inoculated with a bacterial suspension that reconstitutes the media. During incubation, metabolism produces color changes that are either spontaneous or revealed by the addition of reagents. The reactions are read according to the reading table and the identification is obtained by referring to the analytical profile index (api) or using the identification software.

Find detailed information about API 20 E in this post: API 20E Test System: Results and Interpretations

API 20 NE

API 20 NE is a standardized system for the identification of non-fastidious, non-enteric Gram-negative rods (e.g. Pseudomonas, Acinetobacter, Flavobacterium, Moraxella, Vibrio, Aeromonas, etc.) and a database. The API 20 NE strip consists of 20 microtubes (for 8 conventional tests and 12 assimilation tests) containing dehydrated substrates.

  1. The conventional tests are inoculated with a saline bacterial suspension which reconstitutes the media. During incubation, metabolism produces color changes that are either spontaneous or revealed by the addition of reagents.
  2. The assimilation tests are inoculated with a minimal medium and the bacteria grow if they are capable of utilizing the corresponding substrate.

The reactions are read according to the reading table and the identification is obtained by referring to the analytical profile index (API) or using the identification software.

API 50 CHB/ CHE

API 50 CHB/E medium is used for the identification of Bacillus and related genera, as well as Gram-negative rods belonging to the Enterobacteriaceae and Vibrionaceae families. It is a ready-to-use medium that allows the fermentation of the 49 carbohydrates on the API 50 CH strip.

A suspension is made in the medium with the microorganism to be tested and each tube of the strip is then inoculated with the suspension. During incubation, fermentation of carbohydrates is detected by the color change of the pH indicator. The results make up the biochemical profile which is used by the identification software to identify the strain. The API 20 E strip may be used in association with the API 50 CH strip to provide supplementary tests for Enterobacteriaceae and Vibrionaceae.

API test methods for the identification of gram negative bacilli

API STAPH and ID 32 STAPH

API Staph is a miniaturized biochemical test system for the identification of the genera Staphylococcus and Micrococcus.
The API Staph strip consists of 20 microtubes containing dehydrated substrates. These microtubes are inoculated with a bacterial suspension, prepared in API Staph medium, that reconstitutes the tests. During incubation, metabolism produces color changes that are either spontaneous or revealed by the addition of reagents. The reactions are read according to the reading table and the organism is identified by referring to the analytical profile index or using the identification software.

API test for the identification of gram positive cocci

API 20 STREP and Rapid ID 32 STREP

API 20 Strep is a standardized system combining 20 biochemical tests for the identification of most streptococci and enterococci. The API 20 Strep strip consists of 20 microtubes containing dehydrated substrates for the demonstration of enzymatic activity or the fermentation of sugars.

API 20 Strep Test
API 20 Strep test system

The reactions are read according to the reading table and the identification is obtained by referring to the analytical profile index or using the identification software.

API 20C AUX and ID 32 C

API 20 C AUX and ID 32 C is used for the identification of Candida, Cryptococcus, Geotrichum, Kloeckera, Pichia, Rhodoturela and Trichosporon.

Identification of yeast by API test methods

API CANDIDA

API Candida is a standardized system for the identification of frequently encountered yeasts (Candida, Cryptococcus, Saccharomyces, and Trichosporon) in clinical microbiology. The API Candida strip consists of 10 tubes containing dehydrated substrates which enable testing of 12 sugar acidification or enzymatic reactions. The reactions produced during incubation are revealed by spontaneous color changes.

API CAMPY

API Campy is a standardized miniature test system for the identification of Campylobacter. The API Campy strip consists of 20 microtubes containing dehydrated substrates. It is made up of two parts.

  1. The first part of the strip (enzymatic and conventional tests) is inoculated with a dense suspension that rehydrates the substrates. During incubation in aerobic conditions, metabolism produces color changes that are either spontaneous or revealed by the addition of reagents.
  2. The second part of the strip (assimilation or inhibition tests) is inoculated with a minimal medium and incubated in microaerophilic conditions. The bacteria grow if they are capable of utilizing the corresponding substrate or if they are resistant to the antibiotic tested. The reactions are read according to the reading table.

The organism is identified using the identification profile list in the package insert or by using identification software.

API for the identification of Gram positive bacilli

API CHL

API 50 CHL is a ready-to-use medium that allows fermentation of 49 carbohydrates and is used for the identification of the genus Lactobacillus and related genera.
A suspension is made in the medium with the microorganism to be tested and each tube of the strip is then inoculated with the suspension. During incubation, the carbohydrates are fermented to acids which produce a decrease in the pH, detected by the change in color of the indicator. The results make up the biochemical profile which is used by the identification software to identify the strain.

API Coryne

API Coryne is a standardized miniature test system for the identification of Corynebacterium in 24 hours. It consists of 20 microtubes containing dehydrated substrates for the demonstration of enzymatic activity or the fermentation of carbohydrates.

The reactions are read according to the reading table and the identification is obtained by referring to the analytical profile index (API) or using the identification software.

API Listeria

API Listeria is a standardized miniature test system for the identification of Listeria. The API Listeria strip consists of 10 microtubes containing dehydrated substrates which enable the performance of enzymatic tests or sugar fermentations.

During incubation, metabolism produces color changes that are either spontaneous or revealed by the addition of reagents. The reactions are read according to the reading table and the identification is obtained by consulting the profile list in the package insert or using the identification software.

API NH

API NH is a standardized miniature system for the identification of Neisseria, Haemophilus (and related general and Moraxella catarrhalis (Branhamella catarrhalis) using a specially adapted database.

The API NH strip consists of 10 microtubes containing dehydrated substrates, which enable the performance of 12 identification tests (enzymatic reactions or sugar fermentation), as well as the detection of a penicillinase. API NH also enables the biotyping of Haemophilus influenzae and Haemophilus parainfluenzae.

Gram negative cocci API NH

For more information please visit BioMérieux’s API identification

Acharya Tankeshwar

Hello, thank you for visiting my blog. I am Tankeshwar Acharya. Blogging is my passion. As an asst. professor, I am teaching microbiology and immunology to medical and nursing students at PAHS, Nepal. I have been working as a microbiologist at Patan hospital for more than 10 years.

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