BactiFlow® Real-time Microbial Analysis with Digital Flow Cytometry

BactiFlow® is based on the proven cell labeling, laser excitation and digital data treatment technology utilized by ScanRDI®, a solid-phase cytometer developed by Chemunex that provides real-time microbial analysis for filterable samples within two hours. A variation on the technology allows non-filterable samples to be analyzed using flow cytometry. The resulting real-time microbial analysis helps pharmaceutical, cosmetics and personal care companies reduce production times and inventories, minimize in-process contamination, release products in 24 hours, reduce costs and improve product quality.

The BactiFlow® System
BactiFlow® is a compact, affordable, microbiology analyzer that offers true real-time microbial testing for non-filterable and filterable samples. Results are delivered in minutes or hours instead of days - a real competitive advantage.

Direct Labeling, Direct Detection and Enumeration
BactiFlow® uses direct fluorescent labeling of viable microorganisms, coupled with an ultra-sensitive, direct counting system by digital flow cytometry. BactiFlow® can detect and enumerate microorganisms without the need for an incubation period or selective enrichment, providing results within 20 minutes. When some enrichment or incubation is needed, results are still provided days faster than traditional methods. Labeling reagents use enzymatic cleavage of a non-fluorescent substrate to liberate free fluorochrome into the cytoplasm . Only metabolically active cells (including spores) can perform this cleavage, even under conditions of stress. Thus, each microbial cell is directly labeled, one by one. Once labeled, samples pass through a quartz flow cell , which forms a narrow analysis stream that ensures microorganisms pass through the laser excitation beam, and are detected and counted one by one. The fluorescent signals of each cell are collected by sensitive detectors and analyzed by digital data processing.

A Simple Protocol
Samples are labeled using Fluorassure® reagents. The labeling step takes about 10 minutes and can also be done with a semiautomatic labeling unit. Once labeling is completed, the sample is loaded into BactiFlow for fully automated analysis. Results are available within 1 minute. Some specific microorganisms can be identified by varying reagents and protocols (e.g. Salmonella).

Fast & Sensitive Analysis
All microorganisms pass individually through a flow cell at a rate of up to 500 cells per second. Each labeled cell fluoresces under laser excitation to be detected one by one and enumerated by sensitive photomultipliers. Sophisticated cell discrimination ensures accurate and consistent differentiation between labeled microorganisms and any auto-fluorescent particles that may be present. Cell counting takes less than 1 minute per sample. Data is displayed as direct cell counts per gram or mL and are stored on a PC for complete traceability. Neither calibration nor operator interpretation is necessary.

Fully Traceable Results in Hours, Not Days
Results are fully traceable. Data output is in the form of a tabulated result sheet, which includes: operator and sample identification, time and date stamps, control data and a comprehensive result report - all in a totally secure password-protected format. BactiFlow® provides a range of applications (TVC, Fungi, water testing, raw materials, bulk product, final-product release, environmental testing, etc.) that can save 6 to 12 days in the production cycle and reduce warehousing costs, production downtimes and product losses.

High sensitivity and large measuring range
The sensitivity, linearity and reproducibility of BactiFlow® have been evaluated. In all cases, good correlation between BactiFlow® and the traditional plate-count method was proven. The analyzer had a direct sensitivity with results available within minutes of less than 100 cells per g or mL. With the presence/absence protocol, the sensitivity is 1 count/g or mL. The system is linear over a wide range of counts up to 105 counts per g or mL.

A Fully Automated Option
A fully automated version of BactiFlow® is available via the D-Count, which offers automatic sample loading (a capacity of 64 samples per batch including positive and negative controls) and automatic cell labeling (controlled incubation temperature and time).

Summary
The availability of real-time ultra-sensitive microbial testing solutions by Chemunex now offers laboratories an affordable opportunity to switch to a proactive approach to assessing the quality of their manufacturing systems and process materials. Having results within minutes or hours, instead of days, with a high sensitivity creates, for the first time, the opportunity for companies to correct contamination problems as they arise, thus improving overall efficiency and profitability.


This article is taken from the Nov-Dec 2005, Rapid Microbiology Newsletter - A newsletter for the Rapid Micro User's Group™