Bacitracin

Bacitracin	Last updated: 08/09/2025
(Not known by any other names)

GENERAL INFORMATION

Description

A broad spectrum complex polypeptide antibiotic used primarily against gram-positive infections often in combination with other antibacterial compounds such as tetracyclin or prednisolone

Examples of veterinary uses

Used to treart mastitis in lactating cows. Sometimes used as a growth promotor but now banned in many countries.

Examples of species treated

Meat poultry; Pigs; Sheep; Cattle; Rabbits

Approval status

VMR 2013/2033 approval status (GB/UK)

Not approved

EU Regulatory approval status

Not approved

Chemical structure

Isomerism

Bacitracin exhibits structural isomerism due to its nature as a mixture of closely related cyclic peptides, each differing slightly in amino acid composition and stereochemistry. The primary component, Bacitracin A, is the most biologically active, but other isomers like Bacitracin B1, B2, B3, C1–C3, H1–H3, and F are also present in commercial preparations. These isomers arise from variations in the sequence and configuration of amino acids, including the presence of both D- and L-forms, and substitutions at specific positions, such as different side chains on isoleucine or modifications to the thiazoline ring structure. The cyclic nature of bacitracin, combined with its nonribosomal peptide synthesis, allows for incorporation of non-proteinogenic amino acids and unusual building blocks like thiazole and thiazoline rings, contributing to conformational flexibility and multiple isomeric forms.

Chemical formula

C₆₆H₁₀₃N₁₇O₁₆S

Canonical SMILES

CCC(C)C1C(=O)NC(C(=O)NC(C(=O)NC(C(=O)NC(C(=O)NCCCCC(C(=O)NC(C(=O)N1)CCCN)NC(=O)C(C(C)CC)NC(=O)C(CCC(=O)O)NC(=O)C(CC(C)C)NC(=O)C2CSC(=N2)C(C(C)CC)N)CC(=O)N)CC(=O)O)CC3=CN=CN3)CC4=CC=CC=C4

Isomeric SMILES

CC[C@H](C)[C@@H]1C(=O)N[C@@H](C(=O)N[C@H](C(=O)N[C@@H](C(=O)N[C@H](C(=O)NCCCC[C@@H](C(=O)N[C@@H](C(=O)N1)CCCN)NC(=O)[C@H]([C@@H](C)CC)NC(=O)[C@@H](CCC(=O)O)NC(=O)[C@H](CC(C)C)NC(=O)[C@@H]2CSC(=N2)[C@H]([C@@H](C)CC)N)CC(=O)N)CC(=O)O)CC3=CN=CN3)CC4=CC=CC=C4

International Chemical Identifier key (InChIKey)

CLKOFPXJLQSYAH-KWOGWQNJSA-N

International Chemical Identifier (InChI)

InChI=1S/C66H103N17O16S/c1-9-35(6)52(69)66-81-48(32-100-66)63(97)76-43(26-34(4)5)59(93)74-42(22-23-50(85)86)58(92)83-53(36(7)10-2)64(98)75-40-20-15-16-25-71-55(89)46(29-49(68)84)78-62(96)47(30-51(87)88)79-61(95)45(28-39-31-70-33-72-39)77-60(94)44(27-38-18-13-12-14-19-38)80-65(99)54(37(8)11-3)82-57(91)41(21-17-24-67)73-56(40)90/h12-14,18-19,31,33-37,40-48,52-54H,9-11,15-17,20-30,32,67,69H2,1-8H3,(H2,68,84)(H,70,72)(H,71,89)(H,73,90)(H,74,93)(H,75,98)(H,76,97)(H,77,94)(H,78,96)(H,79,95)(H,80,99)(H,82,91)(H,83,92)(H,85,86)(H,87,88)/t35-,36-,37-,40-,41+,42+,43-,44+,45-,46-,47+,48-,52-,53-,54+/m0/s1

2D structure diagram/image available?

Yes

General status

Veterinary substance type

Antibiotic, Antibacterial, Antimicrobial, Medicated feed additive, Growth promotor

Substance groups

Polypeptide complex

Minimum active substance purity

Known relevant impurities

Substance origin

Natural

Mode of action

Inhibits the biosynthesis of bacterium cell wall

Molecular targets

[C55-isoprenyl pyrophosphate, Antagonist], [Insulin-degrading enzyme, Antagonist]; [Alpha-2-macroglobulin, Antagonist]

CAS RN

1405-87-4

EC number

215-786-2

CIPAC number

US EPA chemical code

PubChem CID

Therapeutic Class

Alimentary tract & metabolism: Intestinal anti-infective

ATCvet Code

QA07AA93

Controlled Drug?

Regulation 37/2010 MRL Classification

Allowed substance (Table 1: Bovine, Rabbit)

Molecular mass

1422.69

PIN (Preferred Identification Name)

IUPAC name

(4R)-4-[(2S)-2-({2-[(1S)-1-amino-2-methylbutyl]- 4,5-dihydro-1,3-thiazol-5-yl}formamido)-4-methylpentanamido]-4-{[(1S)- 1-{[(3S,6R,9S,12R,15S,18R,21S)- 18-(3-aminopropyl)-12-benzyl-15-(butan-2-yl)-3-(carbamoylmethyl)- 6-(carboxymethyl)-9-(1H-imidazol-5-ylmethyl)-2,5,8,11,14,17,20- heptaoxo-1,4,7,10,13,16,19-heptaazacyclopentacosan-21-yl]carbamoyl}- 2-methylbutyl]carbamoyl}butanoic acid

CAS name

Forever chemical

Other status information

Banned in EU as growth promotor; Not approved as feed additive in EU

Relevant Environmental Water Quality Standards

Physical state

A hygroscopic solid which is white to yellow-brown in colour depending on purity

Related substances & organisms

bacitracin zinc

bacitracin methylenedisalicylic acid

Commercial

Property

Product

Manufacturer

Authorisation Route

Legal Class (GB/UK)

Availability status

Considered obsolete but may be available in some countries

Introduction & key dates

1945, isolated

Example products (past and present) using this active

Formulation and application details

Usually formulated as a medicated feed premix

Commercial production

Bacitracin is produced through a microbial fermentation process using strains of Bacillus subtilis or Bacillus licheniformis, which naturally synthesise the antibiotic as part of their secondary metabolism. The bacteria are cultivated in a nutrient-rich medium under carefully controlled conditions of temperature, pH, and aeration to maximize bacitracin yield. Once fermentation is complete, the broth is subjected to filtration to remove biomass, followed by solvent extraction, often using butanol or ether, to isolate the active compound. The crude extract is then purified through precipitation and crystallisation, sometimes aided by pH adjustment and the addition of agents like calcium salts. The final product, typically a mixture of bacitracin A and related isomers, is dried and milled into a powder for formulation.

Impact on climate of production and use

As microbial-based products tend to use fermentation-based production processes rather than chemical synthesis, they typically have a lower fossil fuel input in formulation and active ingredient creation, and also have reduced downstream emissions due to biodegradability and minimal soil disruption, their life-cycle GHG emissions are expected to be low. Whilst hard and precise data is not available, broad estimates suggest that typically emissions are likely to be below 5 kg CO₂e/kg.

ENVIRONMENTAL FATE

Property

Value

Source; quality score; and other information

Interpretation

Solubility - In water at 20 °C (mg l⁻¹)

Solubility - In organic solvents at 20 °C (mg l⁻¹)

750000

Ethanol

Melting point (°C)

223

Boiling point (°C)

Decomposes before boiling

Degradation point (°C)

Flashpoint (°C)

Octanol-water partition coefficient at pH 7, 20 °C

1.58 X 10^-01

Calculated

Log P

-0.8

Low

Fat solubility of residues

Solubility

Data type

Density (g ml⁻¹)

Dissociation constant pKa) at 25 °C

Vapour pressure at 20 °C (mPa)

Henry's law constant at 25 °C (Pa m³ mol⁻¹)

Volatilisation as max % of applied dose lost

From plant surface

From soil surface

Maximum UV-vis absorption L mol⁻¹ cm⁻¹

Surface tension (mN m⁻¹)

Refractive Index

Environmental release

Substance may enter the environment via the urine of treated animals or by leaching from spilt medicated feed.

Degradation

Property

Value

Source; quality score; and other information

Interpretation

Soil degradation (days) (aerobic)

DT₅₀ (typical)

Non-persistent

DT₅₀ (lab at 20 °C)

DT₅₀ (field)

DT₉₀ (lab at 20 °C)

DT₉₀ (field)

Note

General literature DT₅₀ range 12-22.5 days

Manure DT₅₀ (days)

22.5

Soil & chicken manure at 20 °C

Aqueous photolysis DT₅₀ (days) at pH 7

Value

Note

Aqueous hydrolysis DT₅₀ (days) at 20 °C and pH 7

Value

Note

Water-sediment DT₅₀ (days)

Water phase only DT₅₀ (days)

Sediment phase only DT₅₀ (days)

Air degradation

As this parameter is not normally measured directly, a surrogate measure is used: ‘Photochemical oxidative DT₅₀’. Where data is available, this can be found in the Fate Indices section below.

Decay in stored produce DT₅₀

Soil adsorption and mobility

Property

Value

Source; quality score; and other information

Interpretation

Linear

K_d (mL g⁻¹)

108

K_oc (mL g⁻¹)

Notes and range

Sandy soils K_d range 5.8-8.0 mL g⁻¹, Clay soils K_d rage 169-250 mL g⁻¹

Freundlich

K_f (mL g⁻¹)

K_foc (mL g⁻¹)

¹/_n

Notes and range

pH sensitivity

Fate indices

Property

Value

Source; quality score; and other information

Interpretation

GUS leaching potential index

Bio-concentration factor

BCF (l kg⁻¹)

Low risk

Based on LogP < 3

Low risk

CT₅₀ (days)

Known soil and groundwater metabolites

None

Other known metabolites

Metabolite name and reference

Aliases

Formation medium / Rate

Estimated maximum occurrence fraction

desamidobasitracin

Chickens; Pigs

ECOTOXICOLOGY

Terrestrial ecotoxicology

Property

Value

Source; quality score; and other information

Interpretation

Mammals - Acute oral LD₅₀ (mg kg⁻¹)

> 3751

Mouse

Low

Mammals - Short term dietary NOEL

(mg kg⁻¹)

(ppm diet)

Mammals - Chronic 21d NOAEL (mg kg⁻¹ bw d⁻¹)

Birds - Acute LD₅₀ (mg kg⁻¹)

> 316

Colinus virginianus

Moderate

Birds - Short term dietary (LC₅₀/LD₅₀)

Birds - Chronic 21d NOEL (mg kg⁻¹ bw d⁻¹)

Earthworms - Acute 14 day LC₅₀ (mg kg⁻¹)

Earthworms - Chronic NOEC, reproduction (mg kg⁻¹)

Soil micro-organisms

Collembola

Acute LC₅₀ (mg kg⁻¹)

Chronic NOEC (mg kg⁻¹)

Non-target plants

Vegetative vigour ER₅₀ (g ha⁻¹)

Seedling emergence ER₅₀ (g ha⁻¹)

Honeybees (Apis spp.)

Contact acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)

Oral acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)

Unknown mode acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)

Chronic

Notes

Bumblebees (Bombus spp.)

Contact acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)

Oral acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)

Mason bees (Osmia spp.)

Contact acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)

Oral acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)

Other bee species (1)

Acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg insect⁻¹)

Mode of exposure

Other bee species (2)

Acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg insect⁻¹)

Mode of exposure

Beneficial insects (Ladybirds)

Beneficial insects (Lacewings)

Beneficial insects (Parasitic wasps)

Beneficial insects (Predatory mites)

Beneficial insects (Ground beetles)

Aquatic ecotoxicology

Property

Value

Source; quality score; and other information

Interpretation

Temperate Freshwater Fish - Acute 96 hour LC₅₀ (mg l⁻¹)

> 4.0

Salmo gairdneri

Moderate

Temperate Freshwater Fish - Chronic 21 day NOEC (mg l⁻¹)

Tropical Freshwater Fish - Acute 96 hour LC₅₀ (mg l⁻¹)

Temperate Freshwater Aquatic invertebrates - Acute 48 hour EC₅₀ (mg l⁻¹)

30.5

Daphnia magna

Moderate

Temperate Freshwater Aquatic invertebrates - Chronic 21 day NOEC (mg l⁻¹)

Daphnia magna

Moderate

Tropical Freshwater Aquatic invertebrates - Acute 48 hour EC₅₀ (mg l⁻¹)

Aquatic crustaceans - Acute 96 hour LC₅₀ (mg l⁻¹)

Sediment dwelling organisms - Acute 96 hour LC₅₀ (mg l⁻¹)

Sediment dwelling organisms - Chronic 28 day NOEC, static, water (mg l⁻¹)

Sediment dwelling organisms - Chronic 28 day NOEC, sediment (mg kg⁻¹)

Aquatic Plants (free-floating, fonds growth, fresh) - 7 day (mg l⁻¹)

Aquatic plants (rooted, growth rate, fresh) - 14 day (mg l⁻¹)

Algae - Acute (growth rate, fresh; mg l⁻¹)

Algae - Chronic (growth rate, fresh; mg l⁻¹)

Mesocosm study data

NOEAEC mg l⁻¹

Marine bivalves

HUMAN HEALTH AND PROTECTION

General

Property

Value

Source; quality score; and other information

Interpretation

Threshold of Toxicological Concern (Cramer Class)

High (class III)

Mammals - Acute oral LD₅₀ (mg kg⁻¹)

> 3751

Mouse

Low

Mammals - Dermal LD₅₀ (mg kg⁻¹ body weight)

Mammals - Inhalation LC₅₀ (mg l⁻¹)

Other Mammal toxicity endpoints

Intraperitoneal LD₅₀ = 190 mg kg⁻¹

Rat

Subcutaneous LD₅₀ = 1300 mg kg⁻¹

Mouse

ADI - Acceptable Daily Intake (mg kg⁻¹ bw day⁻¹)

ARfD - Acute Reference Dose (mg kg⁻¹ bw day⁻¹)

AAOEL - Acute Acceptable Operator Exposure Level (mg kg⁻¹ bw day⁻¹)

AOEL - Acceptable Operator Exposure Level - Systemic (mg kg⁻¹ bw day⁻¹)

Dermal penetration studies (%)

Dangerous Substances Directive 76/464

Exposure Routes

Public

Occupational

Poisonous by intraperitoneal and intravenous routes

Mammalian dose elimination route and rate

Some slight metabolism. Almost all of dose given orally is excreted in the urine within 24 hr.

Health issues

Specific human health issues

Carcinogen

Genotoxic

Endocrine disruptor

; ; ; ;

No data found

Reproduction / development effects

Acetyl cholinesterase inhibitor

Neurotoxicant

No data found

Respiratory tract irritant

Skin irritant

Skin sensitiser

No data found

Eye irritant

Phototoxicant

No data found

General human health issues

May cause contact dermititis or skin sensitisation
May cause gastrointestinal problems
May cause delayed hypersensitivity

Handling issues

Property

Value and interpretation

General

Hygroscopic

CLP classification 2013

WHO Classification

Not listed (Not listed)

UN Number

Not regulated

Waste disposal & packaging

Shelf-life, storage, stability and reactivity

Protect from light. Store <8 DegC

TRANSLATIONS

Language

Name

English

bacitracin

French

bacitracine

German

Danish

Italian

Spanish

bacitracina

Greek

Polish

Swedish

Hungarian

Dutch

Norwegian

Record last updated:	08/09/2025
Contact:	aeru@herts.ac.uk
Please cite as:	Lewis, K.A., Tzilivakis, J., Warner, D. and Green, A. (2016) An international database for pesticide risk assessments and management. Human and Ecological Risk Assessment: An International Journal, 22(4), 1050-1064. DOI: 10.1080/10807039.2015.1133242