chloramphenicol

CHEBI:17698 ·resolve ·ANTIBACTERIAL ·EXACT REVIEWED

An organochlorine compound that is dichloro-substituted acetamide containing a nitrobenzene ring, an amide bond and two alcohol functions. — ChEBI

Classification

phenicol antibioticARO:3000387

Strictly broader compounds or drug classes this molecule belongs to.

Label unavailable CHEBI:23824
Label unavailable CHEBI:35716
Label unavailable CHEBI:36683
Label unavailable CHEBI:37622
phenicol antibiotic ARO:3000387

Chemical structure

Computed structure properties
Molecular formula	C11H12Cl2N2O5
Charge	0
Average mass	323.132 Da
Monoisotopic mass	322.01233 Da
Source	ChEBI
InChIKey	WIIZWVCIJKGZOK-RKDXNWHRSA-N

SMILES

O=C(N[C@H](CO)[C@H](O)c1ccc([N+](=O)[O-])cc1)C(Cl)Cl

InChI

InChI=1S/C11H12Cl2N2O5/c12-10(13)11(18)14-8(5-16)9(17)6-1-3-7(4-2-6)15(19)20/h1-4,8-10,16-17H,5H2,(H,14,18)/t8-,9-/m1/s1

Also called

Amphicol (BRAND_NAME)— chebi
Chloramex (BRAND_NAME)— chebi
Chlorocid (BRAND_NAME)— chebi
Chlorocol (BRAND_NAME)— chebi
Chloromycetin (BRAND_NAME)— chebi
Econochlor (BRAND_NAME)— chebi
Fenicol (BRAND_NAME)— chebi
Globenicol (BRAND_NAME)— chebi
Halomycetin (BRAND_NAME)— chebi
Oleomycetin (BRAND_NAME)— chebi
Sificetina (BRAND_NAME)— chebi
chloramphenicolum (INN)— chebi
chloramphénicol (INN)— chebi
cloramfenicol (INN)— chebi
2,2-dichloro-N-[(1R,2R)-2-hydroxy-1-(hydroxymethyl)-2-(4-nitrophenyl)ethyl]acetamide (EXACT_SYNONYM)— chebi
(−)-chloramphenicol (EXACT_SYNONYM)— chebi
CHLORAMPHENICOL (EXACT_SYNONYM)— chebi
Chloramphenicol (EXACT_SYNONYM)— chebi
D-(−)-2,2-dichloro-N-(β-hydroxy-α-(hydroxymethyl)-p-nitrophenylethyl)acetamide (EXACT_SYNONYM)— chebi
D-(−)-threo-1-p-nitrophenyl-2-dichloroacetylamino-1,3-propanediol (EXACT_SYNONYM)— chebi
chlornitromycin (EXACT_SYNONYM)— chebi
laevomycetinum (EXACT_SYNONYM)— chebi
levomicetina (EXACT_SYNONYM)— chebi
levomycetin (EXACT_SYNONYM)— chebi
CHL (EXACT_SYNONYM)— aro

Cross-references

Identifiers for this same structure in other resources. An accession that lands on two different structures in this corpus is withheld from both rather than shown here, since it names at most one of them.

Drug registries

Identifiers that name a drug rather than a structure. One of these can cover a parent compound, its salts and its stereoisomers, which this corpus keeps as separate records, so it is not an equivalence of structure.

Patents and articles

Documents about this compound. A patent covers a class and an article covers a topic; neither identifies a structure.

Activity roles

Every antimicrobial role a source asserts for this compound — the unreduced evidence behind its antimicrobial_class.

antimicrobial agent CHEBI:33281
antibacterial drug CHEBI:36047

Source concepts

Every upstream concept that resolved to this record. The merge is the product: this is what shows ChEBI and CARD are describing the same structure.

Upstream concepts merged into this record
Source	Native ID	Label	Minted CURIE	Version
ARO	`ARO:3000385`	chloramphenicol	`antibioticmech:aro-859fb8f49a`	2026-08-30
CHEBI	`CHEBI:17698`	chloramphenicol	`antibioticmech:chebi-9f801b8864`	2026-08-30

Molecular targets

The molecular entity or process this compound acts on. Each target carries evidence — this is a mechanistic claim, not a classification.

antibiotic sensitive peptidyl transferase (23S rRNA) NUCLEIC_ACID DIRECT_BINDING_TARGET

ARO:3000754

CARD/ARO database assertion; target organism, strain, and assay are not specified. 23S rRNA peptidyl-transferase center is asserted as the target. Evidence status: PRIMARY_EVIDENCE_NEEDED. Source: CARD_ARO 2026-08-30 (retrieved 2026-08-30).

ARO:3000754 (CARD/ARO asserts targeted_by_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)

50S ribosomal peptidyl-transferase center RIBOSOMAL_SUBUNIT DIRECT_BINDING_TARGET

An approximately 3.3-3.4-angstrom E. coli ribosome cocrystal directly localized chloramphenicol near the peptidyl-transferase center and resolved species-specific contacts. Evidence status: PRIMARY_EVIDENCE. Source: PRIMARY_LITERATURE 2010-09 (retrieved 2026-09-02).

Escherichia coli NCBITaxon:562

PMID:20876128 (Primary chloramphenicol-bound E. coli ribosome structure (DOI:10.1073/pnas.1007988107).)

Mechanism summary

Mode of action: PROTEIN_SYNTHESIS_INHIBITION microbial target — CURATOR: PMID:20876128 resolved chloramphenicol on the Escherichia coli ribosome at approximately 3.3-3.4 angstrom resolution, directly defining its binding near the 50S peptidyl-transferase center. The study also showed why archaeal or other bacterial ribosome structures cannot always be transferred without species-specific qualification.
Clinical status: APPROVED

Activity spectrum

Measured or curated activity against specific taxa. A number without a method is not an observation — every row here carries an assay.

2 observations · Browse all observations · Complete record (JSON.gz)

Activity observations
Organism	Activity	MIC	Disk diffusion	Assay	Strain	Sample/genome	Evidence
Enterococcus faecalis NCBITaxon:1351	—	>32.0 mg/L	—	Broth microdilution chloramphenicol MIC; modal MIC reported; interpreted using CLSI 2025 M100 S35.	0782	BioSample SAMN15040081	Evidence Page data (JSON.gz)
Enterococcus faecalis NCBITaxon:1351	—	>32.0 mg/L	—	Broth microdilution chloramphenicol MIC; modal MIC reported; interpreted using CLSI 2025 M100 S35.	0780	—	Evidence Page data (JSON.gz)

Resistance mechanisms

93 source-backed resistance determinants or associations, with ARO grounding where reported. Grouped by reported mechanism type.

ANTIBIOTIC_EFFLUX 39

ANTIBIOTIC_EFFLUX
Determinant	ARO ID	Organism	Gene families	Evidence
AcrAB-TolC	ARO:3000384	not organism-specific	—	ARO:3000384 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
AdeIJK	ARO:3000772	not organism-specific	—	ARO:3000772 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
Enterobacter aerogenes acrR with mutation conferring multidrug antibiotic resistance	ARO:3003374	not organism-specific	—	ARO:3003374 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
Escherichia coli mdfA	ARO:3001328	not organism-specific	—	ARO:3001328 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
MdsABC	ARO:3000786	not organism-specific	—	ARO:3000786 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
MexAB-OprM	ARO:3000386	not organism-specific	—	ARO:3000386 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
MexCD-OprJ	ARO:3000797	not organism-specific	—	ARO:3000797 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
MexEF-OprN	ARO:3000798	not organism-specific	—	ARO:3000798 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
MexEF-OprN with MexS mutations conferring resistance to chloramphenicol, ciprofloxacin, and trimethoprim	ARO:3004068	not organism-specific	—	ARO:3004068 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
MexEF-OprN with MexT mutation conferring resistance to chloramphenicol, ciprofloxacin, and trimethoprim	ARO:3004066	not organism-specific	—	ARO:3004066 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
MexEF-OprN with MvaT deletion conferring resistance to chloramphenicol and norfloxacin	ARO:3004070	not organism-specific	—	ARO:3004070 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
MexMN-OprM	ARO:3003703	not organism-specific	—	ARO:3003703 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
MexPQ-OpmE	ARO:3003697	not organism-specific	—	ARO:3003697 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
MexVW-OprM	ARO:3003029	not organism-specific	—	ARO:3003029 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
MexXY-OprM	ARO:3003032	not organism-specific	—	ARO:3003032 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
Rhodococcus fascians cmr	ARO:3002701	not organism-specific	—	ARO:3002701 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
Salmonella enterica cmlA	ARO:3002691	not organism-specific	—	ARO:3002691 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
SmeDEF	ARO:3003054	not organism-specific	—	ARO:3003054 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
Staphylococcus aureus LmrS	ARO:3004572	not organism-specific	—	ARO:3004572 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
Streptomyces lividans cmlR	ARO:3002690	not organism-specific	—	ARO:3002690 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
bmr	ARO:3003007	not organism-specific	—	ARO:3003007 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
cmlA1	ARO:3002693	not organism-specific	—	ARO:3002693 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
cmlA4	ARO:3002694	not organism-specific	—	ARO:3002694 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
cmlA5	ARO:3002695	not organism-specific	—	ARO:3002695 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
cmlA6	ARO:3002696	not organism-specific	—	ARO:3002696 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
cmlA8	ARO:3004665	not organism-specific	—	ARO:3004665 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
cmlA9	ARO:3005043	not organism-specific	—	ARO:3005043 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
cmlB	ARO:3002698	not organism-specific	—	ARO:3002698 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
cmlB1	ARO:3002699	not organism-specific	—	ARO:3002699 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
cmrA	ARO:3002702	not organism-specific	—	ARO:3002702 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
cmx	ARO:3002703	not organism-specific	—	ARO:3002703 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
emrD	ARO:3000309	not organism-specific	—	ARO:3000309 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
fexA	ARO:3002704	not organism-specific	—	ARO:3002704 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
flo	ARO:3003963	not organism-specific	—	ARO:3003963 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
floR	ARO:3002705	not organism-specific	—	ARO:3002705 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
mdtM	ARO:3001214	not organism-specific	—	ARO:3001214 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
pexA	ARO:3004666	not organism-specific	—	ARO:3004666 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
pp-flo	ARO:3002812	not organism-specific	—	ARO:3002812 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
ykkCD	ARO:3003062	not organism-specific	—	ARO:3003062 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)

ANTIBIOTIC_INACTIVATION 34

ANTIBIOTIC_INACTIVATION
Determinant	ARO ID	Organism	Gene families	Evidence
Agrobacterium fabrum chloramphenicol acetyltransferase	ARO:3004451	not organism-specific	—	ARO:3004451 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
Alkalihalobacillus clausii chloramphenicol acetyltransferase	ARO:3004452	not organism-specific	—	ARO:3004452 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
Bacillus pumilus cat86	ARO:3002672	not organism-specific	—	ARO:3002672 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
Campylobacter coli chloramphenicol acetyltransferase	ARO:3004454	not organism-specific	—	ARO:3004454 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
CatU	ARO:3003983	not organism-specific	—	ARO:3003983 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
Clostridium butyricum catB	ARO:3002674	not organism-specific	—	ARO:3002674 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
Enterococcus faecalis chloramphenicol acetyltransferase	ARO:3004458	not organism-specific	—	ARO:3004458 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
Enterococcus faecium chloramphenicol acetyltransferase	ARO:3004456	not organism-specific	—	ARO:3004456 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
Limosilactobacillus reuteri cat-TC	ARO:3002671	not organism-specific	—	ARO:3002671 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
Plasmid-encoded cat (pp-cat)	ARO:3002689	not organism-specific	—	ARO:3002689 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
Pseudomonas aeruginosa catB6	ARO:3002678	not organism-specific	—	ARO:3002678 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
Pseudomonas aeruginosa catB7	ARO:3002679	not organism-specific	—	ARO:3002679 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
Staphylococcus intermedius chloramphenicol acetyltransferase	ARO:3004457	not organism-specific	—	ARO:3004457 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
Streptococcus suis chloramphenicol acetyltransferase	ARO:3004455	not organism-specific	—	ARO:3004455 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
Vibrio anguillarum chloramphenicol acetyltransferase	ARO:3004460	not organism-specific	—	ARO:3004460 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
cat	ARO:3002670	not organism-specific	—	ARO:3002670 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
catA1	ARO:3002683	not organism-specific	—	ARO:3002683 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
catA4	ARO:3004657	not organism-specific	—	ARO:3004657 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
catA8	ARO:3004658	not organism-specific	—	ARO:3004658 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
catB10	ARO:3003110	not organism-specific	—	ARO:3003110 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
catB11	ARO:3004660	not organism-specific	—	ARO:3004660 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
catB2	ARO:3002675	not organism-specific	—	ARO:3002675 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
catB3	ARO:3002676	not organism-specific	—	ARO:3002676 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
catB8	ARO:3002680	not organism-specific	—	ARO:3002680 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
catB9	ARO:3002681	not organism-specific	—	ARO:3002681 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
catD	ARO:3002682	not organism-specific	—	ARO:3002682 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
catII	ARO:3002684	not organism-specific	—	ARO:3002684 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
catII from Escherichia coli K-12	ARO:3004656	not organism-specific	—	ARO:3004656 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
catIII	ARO:3002685	not organism-specific	—	ARO:3002685 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
catP	ARO:3002686	not organism-specific	—	ARO:3002686 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
catQ	ARO:3002687	not organism-specific	—	ARO:3002687 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
catS	ARO:3002688	not organism-specific	—	ARO:3002688 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
catV	ARO:3004357	not organism-specific	—	ARO:3004357 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
cmlv	ARO:3002700	not organism-specific	—	ARO:3002700 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)

ANTIBIOTIC_TARGET_ALTERATION 11

ANTIBIOTIC_TARGET_ALTERATION
Determinant	ARO ID	Organism	Gene families	Evidence
Escherichia coli 23S rRNA with mutation conferring resistance to chloramphenicol	ARO:3004150	not organism-specific	—	ARO:3004150 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
Escherichia coli soxR with mutation conferring antibiotic resistance	ARO:3003381	not organism-specific	—	ARO:3003381 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
Escherichia coli soxS with mutation conferring antibiotic resistance	ARO:3003511	not organism-specific	—	ARO:3003511 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
Halobacterium halobium 23S rRNA mutation conferring resistance to chloramphenicol	ARO:3004180	not organism-specific	—	ARO:3004180 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
cfr(B)	ARO:3004649	not organism-specific	—	ARO:3004649 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
cfrA	ARO:3003441	not organism-specific	—	ARO:3003441 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
cfrC	ARO:3004146	not organism-specific	—	ARO:3004146 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
cipA	ARO:3003907	not organism-specific	—	ARO:3003907 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
clbA	ARO:3002814	not organism-specific	—	ARO:3002814 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
clbB	ARO:3002815	not organism-specific	—	ARO:3002815 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
clbC	ARO:3002816	not organism-specific	—	ARO:3002816 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)

UNKNOWN 6

UNKNOWN
Determinant	ARO ID	Organism	Gene families	Evidence
CMLA6-associated chloramphenicol resistance in native isolate SOF-1 Same-isolate gene/phenotype co-occurrence, not proof that CMLA6 alone caused resistance. The paper names CMLA6 and reports the native isolate phenotype as data not shown; no zone diameter or clinical breakpoint interpretation is inferred. Its beta-lactam experiments in other hosts are not chloramphenicol evidence for this isolate. UniProtKB:Q933G9 is retained as reference context only: it combines CmlA6 and cmlA1 annotations from separate source contexts. The source-reported deposit AF294653.1 is not a genome assembly. No exact experimental protein, allele, strain TaxID or genome is assigned. Compound scope follows named chloramphenicol; the tested preparation was not independently re-identified.	—	Pseudomonas aeruginosa `NCBITaxon:287` strain SOF-1	cmlA-like	PMID:11353602 (Selected publisher Results and Discussion: native SOF-1 disk-diffusion resistance statement and CMLA6 identification; accession statement AF294653. The beta-lactam MIC table does not supply a chloramphenicol measurement.) Source-reported disk diffusion
flo co-occurrence with chloramphenicol resistance in avian isolate 5334 Same-isolate co-occurrence, not isolated-gene causation or a new clinical breakpoint interpretation. Other determinants were not excluded. No exact experimental protein, allele, strain TaxID or genome is assigned. Bovine UniProtKB:Q9F0D9/AF252855 is not assigned to these avian isolates. Named compound identity is retained; the tested preparation was not independently re-identified.	—	Escherichia coli `NCBITaxon:562` strain 5334	flo	PMID:10639375 (Table 1 and adjacent native-isolate phenotype and hybridization results. Qualitative co-occurrence only.) Source-reported disk diffusion
flo co-occurrence with chloramphenicol resistance in avian isolate 5790 Same-isolate co-occurrence, not isolated-gene causation or a new clinical breakpoint interpretation. Other determinants were not excluded. No exact experimental protein, allele, strain TaxID or genome is assigned. Bovine UniProtKB:Q9F0D9/AF252855 is not assigned to these avian isolates. Named compound identity is retained; the tested preparation was not independently re-identified.	—	Escherichia coli `NCBITaxon:562` strain 5790	flo	PMID:10639375 (Table 1 and adjacent native-isolate phenotype and hybridization results. Qualitative co-occurrence only.) Source-reported disk diffusion
flo co-occurrence with chloramphenicol resistance in avian isolate 5840 Same-isolate co-occurrence, not isolated-gene causation or a new clinical breakpoint interpretation. Other determinants were not excluded. No exact experimental protein, allele, strain TaxID or genome is assigned. Bovine UniProtKB:Q9F0D9/AF252855 is not assigned to these avian isolates. Named compound identity is retained; the tested preparation was not independently re-identified.	—	Escherichia coli `NCBITaxon:562` strain 5840	flo	PMID:10639375 (Table 1 and adjacent native-isolate phenotype and hybridization results. Qualitative co-occurrence only.) Source-reported disk diffusion
flo co-occurrence with chloramphenicol resistance in avian isolate 6468 Same-isolate co-occurrence, not isolated-gene causation or a new clinical breakpoint interpretation. Other determinants were not excluded. No exact experimental protein, allele, strain TaxID or genome is assigned. Bovine UniProtKB:Q9F0D9/AF252855 is not assigned to these avian isolates. Named compound identity is retained; the tested preparation was not independently re-identified.	—	Escherichia coli `NCBITaxon:562` strain 6468	flo, cmlA	PMID:10639375 (Table 1 and adjacent native-isolate phenotype and hybridization results. Qualitative co-occurrence only.) Source-reported disk diffusion
flo/cmlA-positive bovine subgroup associated with chloramphenicol resistance Subgroup co-occurrence, not sole-gene causation or an assertion about every study isolate. Discordant source subgroups are not merged. Florfenicol categories borrow bovine-respiratory criteria; no E. coli clinical breakpoint is inferred. UniProtKB:Q9F0D9/AF252855.1 is study-linked reference context, not a subgroup-wide allele or genome assignment. EC56 belongs to a later submission and is not substituted for this subgroup. No exact experimental protein, allele, strain TaxID or genome is assigned. Named compound identity is retained; the tested preparation was not independently re-identified.	—	Escherichia coli `NCBITaxon:562`	flo, cmlA	PMID:11101601 (Table 2 flo/cmlA-positive row and adjacent cohort results; assay and accession statements. Qualitative subgroup association only.) NCCLS broth microdilution

ANTIBIOTIC_TARGET_PROTECTION 2

ANTIBIOTIC_TARGET_PROTECTION
Determinant	ARO ID	Organism	Gene families	Evidence
optrA	ARO:3003746	not organism-specific	—	ARO:3003746 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)
poxtA	ARO:3004470	not organism-specific	—	ARO:3004470 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)

REDUCED_PERMEABILITY 1

REDUCED_PERMEABILITY
Determinant	ARO ID	Organism	Gene families	Evidence
Serratia marcescens Omp1	ARO:3004128	not organism-specific	—	ARO:3004128 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000385 (chloramphenicol); database assertion, not a primary citation.)

Causal graphs

Evidence-backed mechanism graphs: how the compound reaches its target, what the target does, and how the effect propagates to growth inhibition or death.

Chloramphenicol blocks the 50S peptidyl-transferase center MECHANISTIC

Chloramphenicol binds the 23S rRNA peptidyl-transferase center of the bacterial large ribosomal subunit and blocks peptide-bond formation by the translation elongation complex.

Nodes — chloramphenicol_50s_peptidyl_transferase_inhibition
Node	Label	Type	Grounding
`chloramphenicol`	chloramphenicol	COMPOUND	`CHEBI:17698`
`peptidyl_transferase_center_23s_rrna`	23S rRNA peptidyl-transferase center	RNA	`ARO:3000754`
`chloramphenicol_bound_ptc`	chloramphenicol-bound peptidyl-transferase center	STATE	REVIEWED_LABEL_ONLY
`peptide_bond_formation`	ribosomal peptide-bond formation	BIOLOGICAL_PROCESS	REVIEWED_LABEL_ONLY
`protein_synthesis`	bacterial protein synthesis	BIOLOGICAL_PROCESS	REVIEWED_LABEL_ONLY

Edges — chloramphenicol_50s_peptidyl_transferase_inhibition
Subject	Predicate	Object	Evidence
`chloramphenicol`	binds	`chloramphenicol_bound_ptc`	PMID:12860128 (Hansen and colleagues solved a chloramphenicol-bound large ribosomal subunit structure with the drug in a peptidyl-transferase-center crevice.)
`peptidyl_transferase_center_23s_rrna`	participates in	`chloramphenicol_bound_ptc`	PMID:12860128 (The comparative large-subunit structures localized chloramphenicol to a ribosomal RNA site adjacent to the catalytic center.) PMID:35165455 (Syroegin and colleagues resolved bacterial 70S complexes that place chloramphenicol in the catalytic peptidyl-transferase center.)
`chloramphenicol_bound_ptc`	decreases	`peptide_bond_formation`	PMID:35165455 (Nascent-chain ribosome structures explained the context-specific blockade of peptide-bond formation by peptidyl-transferase-center chloramphenicol.)
`peptide_bond_formation`	supports	`protein_synthesis`	PMID:12860128 (The antibiotic-bound ribosome study interpreted chloramphenicol action as competitive inhibition of peptide-bond formation in the large subunit.)

Record-level evidence

PMID:20876128 (Primary exact-chloramphenicol E. coli ribosome structural study.)

Curation history

SEEDED_FROM_SOURCES 2026-08-30 · seed_from_sources
Seeded from data/raw/ inventories (ARO, CHEBI)
RESEEDED_FROM_SOURCES 2026-08-30 · seed_from_sources
Re-seeded from updated data/raw/ inventories
RESEEDED_FROM_SOURCES 2026-08-30 · seed_from_sources
Re-seeded from updated data/raw/ inventories
RESEEDED_FROM_SOURCES 2026-08-31 · seed_from_sources
Re-seeded from updated data/raw/ inventories
RESEEDED_FROM_SOURCES 2026-08-31 · seed_from_sources
Re-seeded from updated data/raw/ inventories
RESEEDED_FROM_SOURCES 2026-08-31 · seed_from_sources
Re-seeded from updated data/raw/ inventories
REVIEWED 2026-09-02 · codex · LLM-assisted
Verified exact ChEBI/CARD identity, structure, roles, class, retained FDA status, and the provenance of 87 CARD resistance assertions; curator-confirmed protein-synthesis inhibition and added the directly bound E. coli 50S target.
CURATED_CAUSAL_GRAPH 2026-09-04 · codex · LLM-assisted
Added a PMID-supported causal graph for chloramphenicol binding to the bacterial 50S peptidyl-transferase center.
RESEEDED_FROM_SOURCES 2026-09-10 · seed_from_sources
Re-seeded from updated data/raw/ inventories
CURATED_RESISTANT_TAXA 2026-09-12 · codex · LLM-assisted
Added one stable-URL CDC/FDA AR Isolate Bank chloramphenicol-resistant Enterococcus faecalis isolate MIC observation.
CURATED_RESISTANT_TAXA 2026-09-13 · codex · LLM-assisted
Added one stable-URL CDC/FDA AR Isolate Bank Panel 10 chloramphenicol-resistant Enterococcus faecalis activity observation for AR-0780.
STRUCTURED_ACTIVITY_BIOSAMPLE_ACCESSIONS 2026-09-26 · codex · LLM-assisted
Structured BioSample accessions on 1 activity_spectrum observation(s) where evidence notes already named exactly one accession.
CURATED_RESISTANCE_EVIDENCE 2026-10-10 · codex · LLM-assisted
Added native SOF-1 CMLA6/chloramphenicol co-occurrence from primary results, without assigning individual causation, an exact experimental UniProt protein, allele or genome. Preserved source-owned assertions and all other fields; whole-record review remains open.
CURATED_RESISTANCE_EVIDENCE 2026-10-10 · codex · LLM-assisted
Added four named native flo co-occurrences and one separate flo/cmlA-positive subgroup association from primary results. Kept mechanism UNKNOWN and UniProt/archive context reference-only; did not assign exact alleles, genomes, a subgroup strain or new clinical breakpoints. Preserved all prior claims, observations, history and other fields; whole-record review remains open.

Provenance

Seeded by scripts/seed_from_sources.py from the committed inventories in data/raw/. View the record (YAML).

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