Antibiotic Medium 39 (USP) - BioReagent

Cat. No.: A1528540

GRADE & PURITY BioReagent

Storage

Room temperature

Shipped In

Normal

Overview

For microbiological assay of antibiotic potency. Preparation method: Weigh 17.5 g of this product in 1 L of distilled or deionized water (the volume may be scaled up or down proportionally), heat with stirring and boil until completely dissolved, dispense, autoclave at 121°C for 15 minutes, cool, and set aside for use.

Specifications

Specifications & Purity

BioReagent

Storage

Room temperature

Shipped In

Normal

Grade

BioReagent

Product Line

Biological Products

Application Protocols

No item-specific, validated protocols are provided in the Product Data. Refer to the current USP monographs and your laboratory SOPs for detailed procedures using Antibiotic Medium 39 (USP).

General workflow outline (for compendial microbiological antibiotic assays):

• Prepare the medium per CoA/Spec Sheet (weighing, dissolution, pH adjustment, sterilization).
• Verify growth promotion using the compendial test organism(s) appropriate to the antibiotic under evaluation.
• For cylinder–plate assays: pour agar plates, seed as directed, place cylinders, and apply reference and sample solutions; incubate and measure inhibition zones.
• For turbidimetric assays: inoculate broth with standardized inoculum, add reference/sample, incubate with shaking, and monitor turbidity (e.g., OD) as specified.
• Analyze data per USP statistical models (e.g., parallel-line assay), ensuring system suitability criteria are met.

For any specific parameters (g/L, incubation temperature/time, organism strains), Not specified for this item; refer to CoA/Spec Sheet and USP.

Biological Roles

Role and function (general to antibiotic assay media):

• Nutrient supply: Provides peptides, amino acids, vitamins, and minerals to support the growth of specific test organisms used in USP antibiotic assays. Balanced nutrition is critical for reproducible susceptibility and potency responses.
• Assay matrix: In agar diffusion assays, the medium’s gel matrix (if agar-containing) governs diffusion of antibiotics, influencing inhibition zone diameters. In turbidimetric assays, the broth’s composition affects growth kinetics and optical density changes.
• pH/osmotic environment: Maintains a near-neutral environment compatible with the metabolic requirements of the assay strains, while avoiding components that unduly chelate or inactivate antibiotics.
• Reproducibility: Standardized media composition underpins inter-laboratory comparability for potency calculations against reference standards.

Organism context:

• USP antibiotic assay media are typically paired with defined strains (e.g., Staphylococcus, Micrococcus, Bacillus, or other compendial organisms), selected for sensitivity profiles to the antibiotics under test. Selection of the correct organism-medium pair is essential and is dictated by USP monographs.

Note: Specific strain recommendations and target pH/ionic constituents for Antibiotic Medium 39 should be taken from the current USP and the product’s CoA/Spec Sheet.

Buffer Applications

This product is a complex growth medium, not a dedicated buffering system.

• While some media exhibit intrinsic buffering capacity due to phosphates or proteinaceous components, Antibiotic Medium 39 (USP) should be used as specified for microbiological assays rather than as a general laboratory buffer.
• For experiments requiring precise pH control outside the USP assay’s context, use a defined buffer system (e.g., phosphate, MOPS, HEPES) prepared separately, unless the compendial method explicitly instructs otherwise.

Preparation note: If the USP monograph specifies a target pH for Medium 39, adjust before sterilization and verify after sterilization. Exact values are Not specified for this item; refer to CoA/Spec Sheet.

Green Alternatives

Microbiological media have relatively low EHS impact compared to many chemicals; sustainability considerations focus on preparation and waste handling rather than chemical substitution.

Greener practice options:

• On-demand preparation: Reconstitute only the volume needed to minimize waste of expired sterile media.
• Energy-efficient sterilization: Optimize autoclave loading and cycles; avoid unnecessary extended holds. Use validated 121 °C/15–20 min cycles unless the method dictates otherwise.
• Reusable glassware: Where appropriate, use borosilicate bottles and reusable glass Petri dishes to reduce single-use plastics. Balance with contamination risk and assay requirements.
• Aqueous-only systems: Medium is water-based; avoid adding organic solvents or surfactants unless specified by the method.
• Waste minimization: Autoclave biological waste and segregate for appropriate municipal/industrial composting or landfill according to local rules. Avoid bleach overuse where autoclaving suffices.

Comparison (general):

• Ready-to-use bottled media reduce prep time but increase packaging waste and shipping weight; dehydrated media (this product) reduce transport emissions and allow right-sized preparation.
• Filtration sterilization can save energy for heat-sensitive supplements but generates plastic filter waste; autoclaving base media is typically more material-efficient.

Pharmaceutical Uses

For research use only (from Product Data). In pharmaceutical quality control and development laboratories, media of this class are commonly employed as follows (general, non-clinical):

• Compendial potency testing: Used in microbiological assays of antibiotic potency per USP chapters and monographs, enabling calculation of activity by diffusion or turbidimetric response relative to reference standards.
• Method verification and system suitability: Demonstrates appropriate growth promotion and sensitivity for designated organisms prior to releasing assay runs.
• Training and proficiency testing: Serves as a standardized matrix for training analysts and for inter-lab comparisons.
• Stability/compatibility studies: Supports assessments of how formulation changes or storage conditions affect measured antimicrobial activity via microbiological assays.

Regulatory note:

• The USP label in the name signals intended alignment with compendial procedures; users must ensure the lot-specific CoA/Spec Sheet and internal SOPs conform to the current USP requirements for Medium 39. No therapeutic or clinical uses are implied or intended.

Physical Properties

• Appearance (dehydrated): Not specified for this item; refer to CoA/Spec Sheet.
• Color (solution): Not specified for this item; refer to CoA/Spec Sheet.
• pH (at preparation, literature/general): Microbiological media for antibiotic assays are typically prepared near neutral pH to support test strains; consult USP/CoA for the specified pH for Medium 39.
• Solubility: Designed to be soluble/dispersible in purified water; complete dissolution may require heating and agitation (general practice for dehydrated media).
• Density, BP, MP, refractive index, logP, pKa: Not applicable for a complex solid mixture; Not specified for this item; refer to CoA/Spec Sheet.

Practical notes (general knowledge):

• Dissolution is improved by gradually sprinkling the powder into vigorously stirred, pre-warmed water to minimize clumping.
• Cloudiness prior to sterilization is common; final clarity depends on formulation and whether agar is present. If an agar-containing formulation is used, solution will be viscous when hot and gel upon cooling.

Quality & Grades

• Grade: BioReagent (from Product Data). This indicates the product is suitable for demanding laboratory workflows, offering consistent performance in biological assays when prepared and sterilized correctly.

• USP designation in name: The product is named “Antibiotic Medium 39 (USP),” indicating alignment in intended use with USP microbiological antibiotic assay protocols that reference Medium 39. Users should confirm exact composition, pH, and performance characteristics against the current USP and the item’s CoA/Spec Sheet.

• What to look for on the CoA/Spec Sheet:

  • Formula and component ranges
  • Recommended preparation instructions (g/L, pH before/after sterilization)
  • Growth promotion data with designated test organisms
  • Performance suitability for cylinder–plate or turbidimetric assays (as applicable in USP methods)
  • Microbiological sterility and lot-release criteria

• Stabilizers/antifoams/indicators: Not specified for this item; refer to CoA/Spec Sheet. If indicators (e.g., phenol red) are present in some media, they can affect assay optics—verify before use.

• Consistency and lot qualification: For quantitative antibiotic assays, use a single lot for a full study when possible. If lot changes are necessary, perform method suitability/growth promotion re-verification to maintain continuity of results.

Reaction & Applications

As a microbiological medium, Antibiotic Medium 39 (USP) is not a chemical reagent for synthesis; its “applications” are bioassay-focused.

Key laboratory uses (general to USP antibiotic media):

• Antibiotic potency assays: Preparation of standardized lawns/suspensions of test organisms for cylinder–plate (agar diffusion) or turbidimetric assays as described in USP chapters for microbiological assays of antibiotics.
• Growth promotion testing: Verification that the medium supports robust growth of designated USP test strains at specified incubation conditions.
• Method suitability: Validation of assay precision, linearity, and sensitivity by preparing media according to USP guidance and confirming response to reference standard antibiotic concentrations.
• Inoculum standardization: Achieving reproducible turbidity (e.g., McFarland-like targets) or OD600 ranges to ensure consistent diffusion zones or turbidity changes.

Practical tips:

• Weighing and dissolution: Add powder gradually to preheated, stirred water to avoid clumping; dissolve completely before adjusting pH.
• pH adjustment: If required by the USP monograph, adjust before sterilization; confirm after sterilization as pH can drift.
• Sterilization: Autoclave as directed by your method. Avoid overheating/overholding, which can darken media and reduce performance.
• QC checkpoints: Perform growth promotion with compendial strains. Record lot numbers, preparation parameters, and incubation logs for traceability.

Reaction Conditions

Not applicable to chemical reactions. For microbiological preparation conditions (general practice):

• Dissolution: Gradual addition to purified water with vigorous stirring; heating may be applied to aid dissolution.
• pH: Adjust as required by the USP method for Medium 39 (exact target Not specified for this item; refer to CoA/Spec Sheet).
• Sterilization: Autoclave at 121 °C for 15–20 minutes unless the compendial method specifies an alternative. Avoid extended autoclave holds that can darken media and reduce performance.
• Cooling and pouring: For agar media, cool to ~45–50 °C before pouring plates to minimize condensation (general guideline). For broths, cool to room temperature before use.
• Inoculation and incubation: Follow the organism- and assay-specific parameters defined by USP (strain selection, inoculum density, temperature, time).

Safety & Handling

Always consult the SDS for authoritative safety information.

• GHS Classification / Signal Word / H-Statements / Pictograms: Not specified for this item; refer to SDS.
• Primary hazards (general for dehydrated media): Low acute toxicity expected; dust may cause mechanical irritation to eyes, skin, and respiratory tract. Avoid inhalation of dust and contact with eyes.
• PPE: Laboratory coat, safety glasses or face shield, and suitable gloves (e.g., nitrile). Use dust control measures (local exhaust) when weighing.
• Hygiene: Wash hands after handling. Do not eat or drink in lab areas.
• Incompatibilities: Strong oxidizers and strong acids/bases may degrade organic components. Prevent microbial contamination of the dry medium to maintain quality.
• Sterilization: Typically autoclave at 121 °C for 15–20 min after dissolution (general practice; verify method per USP and CoA for this specific medium).
• Spill response: Avoid creating dust. Sweep or HEPA-vacuum spilled powder; place in closed container for disposal. Rinse area with water.
• First aid (general):
  • Inhalation: Move to fresh air; seek medical attention if irritation persists.
  • Eye contact: Rinse cautiously with water for several minutes; remove contact lenses if present and easy; seek medical advice if irritation continues.
  • Skin contact: Wash with soap and water.
  • Ingestion: Rinse mouth; seek medical advice if unwell.
• Waste disposal: Dispose according to institutional, local, and national regulations. Autoclave used, microbially contaminated media before disposal.

Solvent Selection

This product is a microbiological medium intended to be prepared in water.

• Primary solvent: High-purity water (e.g., ASTM Type 1 or equivalent). Avoid chelators or residual disinfectants that could inhibit growth.
• Polarity/miscibility: Fully water-dispersible/soluble as a complex mixture when heated and stirred. Not intended for dissolution in organic solvents.
• Ionic strength/buffering: Some formulations include salts and weak buffering capacity (general for media), but users should verify and avoid adding external buffers unless the method specifies them, as buffering can alter antibiotic activity/readouts.

Selection guidance:

• Use freshly produced, sterile-filtered or autoclaved water. Residual chlorine/chloramine can inhibit organisms; neutralize if present.
• If your application requires plates, select agar-containing formulation (if applicable). For turbidimetric assays, use the broth formulation specified by USP for Medium 39.

Comparison (general):

• Water vs buffered saline: Water is standard for media preparation; buffered saline is not a substitute for dissolving dehydrated media and can distort osmolarity and assay performance.
• Membrane filtration vs autoclave sterilization: Media with heat-labile supplements (if any are specified by your method) may require sterile filtration post-dissolution; base media are commonly autoclaved. Follow USP method directions.

Storage & Reconstitution

• Storage (as supplied): Room temperature (from Product Data). Keep tightly closed in a dry place. Protect from humidity to prevent caking and microbial contamination.
• Shipping: Normal (from Product Data).
• Shelf life: Not specified for this item; refer to CoA/Spec Sheet and label.

Reconstitution (general guidance for dehydrated media; follow CoA/USP for exact details):

• Water quality: Use freshly prepared, high-purity water. Degas if excessive foaming or bubble formation interferes with assay optics.

• Weighing: Accurately weigh the specified grams per liter (Not specified for this item; refer to CoA/Spec Sheet).

• Dissolution: Add powder gradually to stirred water; heat as needed until fully dissolved. Avoid scorching.

• pH adjustment: If required by USP for Medium 39, adjust before sterilization with sterile acid/base; verify post-sterilization pH.

• Sterilization: Autoclave at 121 °C for 15–20 minutes unless otherwise specified. Do not oversterilize.

• Post-sterilization handling: For agar media, cool to ~45–50 °C and pour plates in a sterile environment. For broth, cool to room temperature and use promptly or store at 2–8 °C short-term; discard if contamination or precipitation occurs (time limits Not specified for this item; refer to CoA/Spec Sheet).

• Research Use Note: For research use only (from Product Data).

Structure & Identity

Antibiotic Medium 39 (USP) is a complex, multi-component microbiological growth medium intended for potency testing and related microbiological assays of antibiotics under USP methodologies.

• SKU: A1528540
• Product Type: Dehydrated culture medium (complex/undefined composition)
• Grade/Purity: BioReagent (from Product Data)
• Molecular Formula: Not applicable for mixtures; Not specified for this item; refer to CoA/Spec Sheet.
• Molecular Weight: Not applicable for mixtures; Not specified for this item; refer to CoA/Spec Sheet.
• CAS: Not assigned for complex media blends
• SMILES / InChI / InChIKey: Not applicable (mixture)

Structural features (descriptive, general knowledge):

• Typically contains a blend of peptones/enzymatic digests (amino acids and peptides), yeast or beef extracts (vitamins, growth factors), carbohydrate/salts, and may include buffering components to support robust bacterial growth for assay reproducibility.
• As a dehydrated powder, it is a heterogeneous mixture; no single 2D chemical structure applies. The functional “architecture” is nutritional rather than structural: nitrogen sources (peptides), carbon/energy sources, and mineral ions to sustain test organisms used in antibiotic assays.

Identity notes:

• The designation “USP” denotes alignment in name and intended use with United States Pharmacopeia microbiological assay media numbering. Specific composition/tolerances for Medium 39 should be verified against the current USP monograph and the item’s CoA/Spec Sheet.

Synthetic Utility

Not applicable. Antibiotic Medium 39 (USP) is a biological growth medium, not a chemical building block or reagent for organic synthesis.

Guidance:

• For chemical synthesis applications, select defined reagents or buffers with specified purity and reactivity. Use this medium only for its intended role in microbiological assays and culture support per USP methodology.

Target Specificity

Not applicable. This product is not an antibody, probe, or targeted biochemical. It is a general-purpose, compendial-style microbiological medium used to culture designated organisms for antibiotic assays.