ESwab™, Anaerobes and Antibiotic Stewardship
December 12, 2017
Multipurpose. Universal. Open platform. Toss those words around a Microbiology lab and expect to see eyes light up like Christmas trees. Add in the fact that the same collection and transport swab maintains viability of aerobic, anaerobic and fastidious bacteria for extended time periods at room temperature, and it’s easy to see why momentum for adoption of ESwab™ collection and transport device is growing quickly in the scientific community.
A quick glance at the tube of liquid Amies and one might think there’s ‘no way’ it maintains anaerobes. But, ESwab™ has some powerful help from its friend, FLOQSwab®, COPAN’s patented brand of flocked swabs. With perpendicular nylon fibers and no inner core to entrap the specimen, flocked swabs facilitate a strong hydraulic uptake of specimen with over 90% recovery of sample. Thus, the dynamic duo is an integral component of the important pre-analytical phase of microbiology for providing adequate storage and survival of potential pathogens prior to analysis.
A recent study, Extensive Evaluation of Fastidious Anaerobic Bacteria Recovery from the COPAN ESwab Transport System, evaluates just how long and how well ESwab™ preserves anaerobes. It is a known fact that “anaerobic infections are difficult to diagnose and treat, because of the often slow in vitro growth, the polymicrobial nature and the increasing antimicrobial resistance.” Laboratory centralization and consolidation typically have positive outcomes. However, centralization poses some significant challenges to healthcare and preanalytical testing in microbiology. When samples need to be transported to an external laboratory, it is critical that they are collected, transported and preserved properly. ESwab™ is an innovative collection and transport system specifically designed to preserve aerobic, anaerobic, and fastidious bacterial species, which helps to alleviate the issue of transit time due to centralization.
Cited in the study, the team tested the recovery on 18 strains of clinical significant pathogenic anaerobes: Bacteroides fragilis, Bacteroides thetaiotaomicron, Finegoldia magna, Bilophila wadsworthia, Parvimonas micra, Fusobacterium necrophorum, Peptostreptococcus anaerobius, Fusobacterium nucleatum, Eggerthella lenta, Porphyromonas asaccharolytica, Propionibacterium acnes, Porphyromonas gingivalis, Prevotella buccae, Clostridium clostridioforme, Prevotella intermedia, Clostridium difficile, Prevotella melaninogenica, and Clostridium ramosum. The goal was to determine the recovery of different anaerobe species at different times and at different bacterial concentrations, in addition to verifying the optimal temperature of storage for the bacterial recovery throughout the different time points.
For the most accurate reading, first a bacterial primary plate was prepared from the organisms. After sufficient growth, a suspension from the primary platewas prepared in nutrient rich broth to achieve a turbidity of 0.5 McF, then the stock suspension was diluted in the ESwab™ container to reach a first inoculum concentration of approximately 1.5 x 10⁷ CFU/mL. In the next steps, the stock suspension was diluted into a nutrient broth medium and from there the suspensions were diluted again in the ESwab™ container. Each of the final inoculum concentration ESwab™ containers were then stored at 2-4°C or at room temperature (22-24°C) for 8 h, 24 h, 48 h, 72 h, and one week. After each duration, the ESwab™ medium was diluted again in nutrient broth medium and 50 µL of each organism suspension was inoculated to duplicate Brucella agar plates, while another 50 µL of the dilution was plated to an anaerobic plate.
Putting ESwab™ to the Test . . . Again!
The team chose to inject the different bacterial inoculums directly into the ESwab™ container mimicking aspiration sampling. This allowed them to quantify the recovery percentage of the different anaerobic bacteria at different storage temperatures and durations.
Ideally, materials for anaerobic testing should be subjected to culture within 3 – 6 hours after sample collection (J. Infect. Chemother., 2011) and evaluated for bacterial recovery within 8 hours post the inoculation. Most samples coming from the clinic can reach the lab to be processed within 8 hours. ESwab™ easily hits the mark by sustaining the tested anaerobes at room temperature or refrigerated. The study concluded that “[a]s such all species (except for Clostridium clostridioforme) were recovered from the eSwab® medium until 24 h post-inoculation, applying inoculum levels as low as 1.5 ×103 CFU/mL. Furthermore 50% of the species included in this study were recovered until 1 week post inoculation.”
By using ESwab™, hospitals can simplify and streamline collection by replacing multiple Stock Keeping Units (SKU) with just one for ESwab™. They can reduce the costs of repeat collection and testing due to the wrong device sent from point of care. And improve patient care by uncovering more accurate results with improved pathogen recovery.
ESwab™ and Antibiotic Stewardship
The benefits don’t stop there because with enhanced pathogen recovery and preservation, labs and physicians can be certain they are diagnosing accurately and prescribing the proper treatment, which are some initiatives that help make up the hallmark of Antibiotic Stewardship.
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