Microgen MID-64-A Gram-Negative Bacterial Identification System (GN A)

Overview

The Microgen MID-64-A Gram-Negative Bacterial Identification System (GN A) is a standardized, microplate-based biochemical identification platform engineered for the rapid and reliable identification of aerobic and facultatively anaerobic Gram-negative bacteria—primarily Enterobacteriaceae and other non-fastidious oxidase-negative, nitrate-reducing, glucose-fermenting bacilli. Operating on classical phenotypic microbiology principles, the system leverages 12 pre-formulated, lyophilized biochemical substrates per test strip to detect enzymatic activity, carbohydrate metabolism, nitrogen utilization, and other physiological traits. Each reaction yields a colorimetric endpoint—either spontaneous or after addition of specific reagents—enabling binary (positive/negative) interpretation. The system is AOAC-PTM certified for performance against reference strains, supporting compliance with ISO 17025-accredited laboratory workflows and routine quality control in clinical microbiology, food safety, pharmaceutical QC, and environmental monitoring laboratories.

Key Features

• AOAC Performance Tested Method (PTM)-certified for accuracy and reproducibility in identifying 44 validated Enterobacteriaceae species and related Gram-negative bacilli
• Pre-lyophilized 12-test strip format (MID-64-A) ensures stability, consistency, and minimal preparation time
• Designed for use with the Microgen MID-60 identification software, which applies probabilistic algorithms (based on a curated database of >300 reference strains) to generate percent likelihood scores and confidence rankings
• Compatible with standard incubation conditions (35–37 °C, non-CO₂, static environment) and requires no specialized instrumentation beyond a calibrated incubator and basic microbiological tools
• Integrated quality control support via included chromogenic reference cards, oxidase test strips, nitrate reagents (A/B), VP I/II, TDA, and Kovac’s reagents
• Storage-stable at 2–8 °C; unopened strips retain full potency until expiry date printed on foil pouch; opened strips remain usable for 14 days when stored with desiccant

Sample Compatibility & Compliance

The MID-64-A system is validated for pure, isolated colonies of Gram-negative bacilli grown on standard media (e.g., TSA, MacConkey, or blood agar) following ≥18–24 h incubation. It identifies organisms within 28 genera—including Escherichia, Klebsiella, Enterobacter, Serratia, Proteus, Morganella, Citrobacter, Salmonella, Shigella, and Yersinia. While GN A alone suffices for oxidase-negative, nitrate-positive, glucose-fermenting isolates, GN B (MID-65) must be used in conjunction for comprehensive profiling of oxidase-positive non-fermenters (e.g., Pseudomonas, Acinetobacter). The system adheres to ISO 7218:2017 (microbiology of food and animal feeding stuffs), supports GLP/GMP documentation requirements, and enables audit-ready traceability when paired with MID-60 software’s built-in user access logs and result history export (CSV/PDF).

Software & Data Management

The optional Microgen MID-60 identification software serves as the analytical engine for result interpretation. It accepts manual entry or barcode-scanned strip codes, cross-references reactions against an updated, taxonomically verified knowledge base, and outputs ranked identifications with probability percentages and interpretive commentary (e.g., “Escherichia coli: 98.7% match; high confidence”). Software features include customizable user permissions, electronic signature capability compliant with FDA 21 CFR Part 11 (when deployed on validated IT infrastructure), audit trail generation, and exportable reports suitable for regulatory submissions. All raw reaction data and final identifications are timestamped and stored locally—no cloud dependency or mandatory subscription.

Applications

• Clinical microbiology labs performing routine ID of stool, urine, wound, and blood culture isolates
• Pharmaceutical manufacturing facilities conducting environmental monitoring (EM) and sterility test follow-up identification
• Food and beverage laboratories verifying pathogen presence (e.g., Salmonella, Shigella) per ISO 6579 and BAM Chapter 4 protocols
• Contract research organizations (CROs) delivering AOAC-validated microbial ID services under GLP conditions
• Academic and public health reference labs requiring cost-effective, low-instrumentation phenotypic confirmation prior to MALDI-TOF or sequencing

FAQ

What bacterial groups does MID-64-A specifically target?
MID-64-A is optimized for oxidase-negative, nitrate-reducing, glucose-fermenting Gram-negative bacilli—predominantly Enterobacteriaceae (44 validated species) and select non-fermenters when used with MID-65 GN B.
Is MID-64-A compatible with automated colony pickers or liquid handling systems?
No—the system is designed for manual inoculation using saline suspension and sterile loops; it does not interface with robotics or plate handlers.
Does the MID-60 software require annual licensing or internet connectivity?
No—MID-60 is a perpetual, offline desktop application; updates are distributed via secure USB or authenticated download without subscription fees.
Can results be integrated into a LIMS?
Yes—MID-60 supports CSV and PDF export of full identification reports, including reaction profiles, confidence metrics, and metadata (user, date, sample ID), enabling seamless ingestion into most LIMS platforms.
What is the shelf life of unopened MID-64-A strips?
Unopened foil pouches are stable for up to 18 months when stored continuously at 2–8 °C; expiration date is printed on each pouch.