OxyPRAS Plus® KVL Blood Agar Plate
OxyPRAS Plus® KVL Blood Agar is a pre-reduced anaerobically sterilized (PRAS) kanamycin vancomycin laked blood agar plate for the selective isolation of gram-negative anaerobic bacteria, especially Bacteroides and Prevotella species, from clinical specimens. Some labs know this medium as LKV or laked blood KV agar. Kanamycin and vancomycin suppress gram-positive organisms and most facultative gram-negatives, laked sheep blood brings out Prevotella pigmentation early, and hemin and vitamin K1 support the fastidious pigmenting strains. The plate arrives ready to inoculate with no post-reduction step.
At a glance
Catalog number: P-KVL-BA (single plate), P-KVL-10 (10-pack). Also in multi-pack M-BKP-3 and as one side of the BBE/KVL bi-plate.
Medium: Tryptic soy agar base with 5% laked sheep blood, hemin 5 mg/L, vitamin K1 1 mg/L, kanamycin, vancomycin. Initial pH 7.5.
Type: Selective, enriched. Gram-negative anaerobes; inhibits gram-positives and most facultatives.
Shelf life: 4 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: Listed as exempt under CLSI M22-A3. Lot QC performed by Oxyrase.
Regulatory: For in vitro diagnostic use. Manufactured in Mansfield, Ohio under ISO 9001:2015.
When to use it
KVL is the selective plate for the gram-negative anaerobes that matter most clinically: the Bacteroides fragilis group, Prevotella, Porphyromonas, and Fusobacterium. Use it on any specimen where those organisms are likely and where gram-positive flora or facultatives could overgrow them, which covers most abscesses, deep wounds, and intra-abdominal, pelvic, and head-and-neck infections. Laked blood makes the black pigment of Prevotella melaninogenica and related species appear a day or two sooner than on whole-blood media, which speeds presumptive identification.
Run it next to OxyPRAS Plus® Brucella for the non-selective baseline. If you also want the Bacteroides fragilis group flagged by esculin reaction, the OxyPRAS Plus® BBE/KVL Bi-Plate puts both selective media on one plate.
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 7.5 ± 0.3. Production lots may be adjusted to offset raw material variance in order to meet performance criteria.
| Component |
Amount |
| Enzymatic digest of casein |
15.0 g |
| Enzymatic digest of animal tissue |
5.0 g |
| Yeast extract |
5.0 g |
| Sodium chloride |
5.0 g |
| L-cysteine |
0.58 g |
| Agar |
15.0 g |
| Hemin |
5.0 mg |
| Vitamin K1 |
1.0 mg |
| Vancomycin |
1.1 mL |
| Kanamycin |
3.82 mL |
| Laked sheep blood |
51.0 mL |
| Sodium bisulfite |
0.1 g |
| Oxyrase® Enzyme System |
proprietary |
Kanamycin inhibits protein synthesis in susceptible organisms and vancomycin blocks cell wall synthesis in gram-positives, which together select for gram-negative anaerobes. Laked blood improves pigmentation of Prevotella melaninogenica and related species. Hemin and vitamin K1 support the pigmenting Bacteroides group and some gram-positive non-spore-forming anaerobes.
Quality control
Samples of every lot are tested to Oxyrase specifications incorporating CLSI M22-A3. The following results are confirmed before release:
| Organism |
ATCC |
Expected result |
| Bacteroides fragilis |
25285 |
Growth in 2 to 3 days |
| Clostridium perfringens |
13124 |
No growth in 2 to 3 days |
| Prevotella melaninogenica |
25845 |
Growth in 2 to 3 days |
| Staphylococcus aureus |
25923 |
No growth in 2 to 3 days |
| Escherichia coli |
25922 |
Growth inhibited in 2 to 3 days |
Uninoculated medium is bright red (laked blood) with no surface imperfections. KVL blood agar is listed as exempt from user quality control under CLSI M22-A3; each laboratory should still establish its own QC program in line with its accreditation requirements, and the organisms above are recommended if you choose to test.
Directions for use
- Allow plates to reach room temperature before use.
- Remove the plate from the pouch.
- Check for contamination, oxidation or discoloration, and the expiration date.
- Inoculate and streak using standard technique.
- Invert and incubate at 35 to 37°C in an anaerobic bag, jar, or chamber.
- Include an anaerobic indicator such as OxyBlue™ to confirm anaerobiosis.
- 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 4 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® KVL 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
- As a selective medium it supports only select organisms. Colony types require additional identification.
- Some kanamycin-resistant facultative gram-negatives and vancomycin-resistant gram-positives may grow. Confirm isolates.
- 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
Is KVL the same as LKV agar?
Yes. KVL, LKV, and laked blood KV agar all describe kanamycin vancomycin laked sheep blood agar. Formulations vary slightly by manufacturer; ours is a tryptic soy base with hemin and vitamin K1.
Why laked blood instead of whole blood?
Laking (lysing) the red cells releases hemin and makes the black pigment of Prevotella melaninogenica and related species visible earlier, often within 48 hours.
Will Clostridium or other gram-positive anaerobes grow on it?
No. Vancomycin suppresses gram-positives, which is the point. Use OxyPRAS Plus® Brucella or PEA to recover gram-positive anaerobes from the same specimen.
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.
Does my lab have to run QC on each lot?
KVL agar is on the CLSI M22-A3 list of media exempt from user QC. Each lot is tested by Oxyrase before release. Your accreditation program may still ask you to document receipt and inspection.
Is it available through my distributor?
Yes, through Fisher Scientific and Cardinal Health, or direct from Oxyrase. Ask us about volume pricing for standing orders.
