OxyPRAS Plus® StrictAna Blood Agar Plate

OxyPRAS Plus® StrictAna Blood Agar is a pre-reduced anaerobically sterilized (PRAS) selective anaerobic blood agar plate for the isolation of obligate anaerobes from clinical specimens. It starts from the same enriched Brucella base as our non-selective plate, with 5% sheep blood, hemin, and vitamin K1, and adds a proprietary selective agent that inhibits most facultative bacteria, including Enterobacteriaceae, staphylococci, and Neisseria. Strict anaerobes grow; the organisms that usually overgrow them do not. The plate arrives ready to inoculate with no post-reduction step.

At a glance

Catalog number: P-SANA-BA (single plate).

Medium: Brucella agar base with 5% defibrinated sheep blood, hemin 5 mg/L, vitamin K1 1 mg/L, proprietary selective agent. Initial pH 7.3.

Type: Selective, enriched. Obligate anaerobes; inhibits most facultatives. Gram-positive and gram-negative anaerobes both grow.

Shelf life: 3 months from manufacture. 28-day minimum guaranteed on arrival.

Storage: 2 to 8°C. Ships at room temperature.

Packaging: Individually sealed oxygen-impermeable pouch.

User QC: Lot QC performed by Oxyrase to CLSI M22-A3.

Regulatory: For in vitro diagnostic use. Manufactured in Mansfield, Ohio under ISO 9001:2015.

When to use it

Most selective anaerobic media choose a side: KVL keeps gram-negatives, PEA keeps gram-positives. StrictAna selects on a different axis. It suppresses the facultatives and keeps the strict anaerobes regardless of Gram reaction, so a single selective plate recovers Bacteroides, Prevotella, Fusobacterium, clostridia, and the anaerobic cocci from the same specimen. That is most useful on heavily polymicrobial material: intra-abdominal and pelvic abscesses, perirectal and decubitus wounds, aspiration pneumonia specimens, and anything where E. coli, Proteus, or staph would otherwise cover the plate by 48 hours.

StrictAna is not a replacement for the non-selective plate. Run it alongside OxyPRAS Plus® Brucella so facultatives are still recovered and reported, and add OxyPRAS Plus® BBE if you want the Bacteroides fragilis group flagged by esculin reaction.

Why PRAS manufacturing matters

Anaerobic media that is poured and packaged in air accumulates oxidation products before it ever reaches your bench. Those products inhibit the most oxygen-sensitive anaerobes, and the effect is invisible: the plate looks fine and simply reports no growth.

OxyPRAS Plus® plates are reduced with the Oxyrase® Enzyme System before sterilization and held in a reduced state through storage and use. In our PRAS vs. non-PRAS comparison, 8 of 30 non-PRAS Brucella plates inoculated with Porphyromonas levii grew nothing at all, while 0 of 30 OxyPRAS Plus® plates failed. OxyPRAS Plus® plates also tolerate up to 2 hours of ambient oxygen exposure during setup without inhibitory oxidation, which gives the bench flexibility to batch work and to use automated streaking platforms.

Read the full data in The Plate That Reports Nothing and the oxygen exposure white paper.

Formulation

Approximate composition per liter of deionized water. Initial pH 7.3 ± 0.2. Production lots may be adjusted to offset raw material variance in order to meet performance criteria.

The proprietary selective agent inhibits most facultatively anaerobic bacteria without affecting obligate anaerobes. Hemin and vitamin K1 support the pigmenting Bacteroides group and some gram-positive non-spore-forming anaerobes. Sheep blood adds nutrients and allows hemolytic reactions to be read.

Quality control

Samples of every lot are tested to Oxyrase specifications incorporating CLSI M22-A3. The following results are confirmed before release:

Uninoculated medium is red with no surface imperfections. Each laboratory should establish its own QC program in line with its accreditation requirements; the organisms above are recommended for user QC.

Directions for use

1. Allow plates to reach room temperature before use.
2. Remove the plate from the pouch.
3. Check for contamination, oxidation (a bright red rather than dark red surface), and the expiration date.
4. Inoculate and streak using standard technique.
5. Invert and incubate at 35 to 37°C in an anaerobic bag, jar, or chamber.
6. Include an anaerobic indicator such as OxyBlue™ to confirm anaerobiosis.
7. Read plates after 2 to 3 days.

Anaerobic incubation is still required. PRAS manufacturing protects the medium before and during setup; it does not replace the anaerobic atmosphere during incubation.

Storage, shelf life and guarantee

Plates ship at room temperature and should be stored at 2 to 8°C on receipt. Expiration is 3 months from date of manufacture; the actual date is printed on each plate. Oxyrase guarantees at least 28 days of shelf life from the ship date, and longer dating can be arranged when you order. If OxyPRAS Plus® StrictAna Blood Agar plates arrive short-dated, contaminated, or oxidized, or fail when used as directed, we refund the purchase price. Contact us with the lot number printed on the plate.

Limitations

• Supports strict anaerobes. Facultative organisms present in the specimen are suppressed, not reported; use a non-selective plate alongside.
• Colony types require additional identification.
• Some beta-hemolytic species can show a greenish reaction that resembles alpha-hemolysis because of the medium’s carbohydrate content.
• The Oxyrase® Enzyme System contains a penicillin-binding protein that may interfere with penicillin and some related antibiotics. Do not use these plates for susceptibility testing.
• Contains material of animal origin. Source animals are documented free of BSE/TSE.

Frequently asked questions

How is StrictAna different from KVL or PEA?

KVL and PEA select by Gram reaction. StrictAna selects by oxygen tolerance: it inhibits facultatives and lets both gram-positive and gram-negative strict anaerobes grow. One plate instead of two for the selective read.

How is it different from the Brucella plate?

Same base medium and supplements. Brucella is non-selective and grows everything, including facultatives. StrictAna adds a selective agent that suppresses facultatives.

What is the selective agent?

It is proprietary. QC data on the insert show inhibition of S. aureus and E. coli and suppression of Proteus swarming, with normal growth of B. fragilis, C. perfringens, P. melaninogenica, and P. anaerobius.

Why is the shelf life 3 months instead of 4?

The selective agent has a shorter stability window than the base medium. The 28-day minimum on arrival still applies.

Do I need to reduce the plates before inoculating?

No. OxyPRAS Plus® plates are reduced during manufacturing and stay reduced in the sealed pouch. Open, inoculate, and incubate.

Is it available through my distributor?

Yes, through Fisher Scientific and Cardinal Health, or direct from Oxyrase. Ask us about volume pricing or an evaluation.