oxacillin

CHEBI:7809 ·resolve ·ANTIBACTERIAL ·EXACT SEEDED

A penicillin antibiotic carrying a 5-methyl-3-phenylisoxazole-4-carboxamide group at position 6β. — ChEBI

Machine-generated and unreviewed. Identity, structure and cross-references come straight from ChEBI's and CARD's own data; no curator has signed off on this record yet.

Classification

penicillin beta-lactamARO:3000008

Strictly broader compounds or drug classes this molecule belongs to.

penicillin CHEBI:17334
penicillin beta-lactam ARO:3000008

Chemical structure

Computed structure properties
Molecular formula	C19H19N3O5S
Charge	0
Average mass	401.444 Da
Monoisotopic mass	401.10454 Da
Source	ChEBI
InChIKey	UWYHMGVUTGAWSP-JKIFEVAISA-N

SMILES

[H][C@]12SC(C)(C)[C@H](C(=O)O)N1C(=O)[C@H]2NC(=O)c1c(-c2ccccc2)noc1C

InChI

InChI=1S/C19H19N3O5S/c1-9-11(12(21-27-9)10-7-5-4-6-8-10)15(23)20-13-16(24)22-14(18(25)26)19(2,3)28-17(13)22/h4-8,13-14,17H,1-3H3,(H,20,23)(H,25,26)/t13-,14+,17-/m1/s1

Also called

2,2-dimethyl-6β-(5-methyl-3-phenyl-1,2-oxazole-4-carboxamido)penam-3α-carboxylic acid (EXACT_SYNONYM)— chebi
(2S,5R,6R)-3,3-dimethyl-6-{[(5-methyl-3-phenylisoxazol-4-yl)carbonyl]amino}-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylic acid (EXACT_SYNONYM)— chebi
(5-methyl-3-phenyl-4-isoxazolyl)penicillin (EXACT_SYNONYM)— chebi
5-methyl-3-phenyl-4-isoxazolyl-penicillin (EXACT_SYNONYM)— chebi
6β-(5-methyl-3-phenylisoxazol-4-yl)penicillanic acid (EXACT_SYNONYM)— chebi
Oxacillin (EXACT_SYNONYM)— chebi
oxazocillin (EXACT_SYNONYM)— chebi
MPI-penicillin (EXACT_SYNONYM)— aro
Ossacillina (EXACT_SYNONYM)— aro
Oxacilina (EXACT_SYNONYM)— aro
Oxacilline (EXACT_SYNONYM)— aro
Oxacillinum (EXACT_SYNONYM)— aro
Oxazocillin (EXACT_SYNONYM)— aro
Oxazocilline (EXACT_SYNONYM)— aro
Prostaphlin (EXACT_SYNONYM)— aro
Prostaphlyn (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 agent CHEBI:33282
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:0000056`	oxacillin	`antibioticmech:aro-42474d1716`	2026-08-30
CHEBI	`CHEBI:7809`	oxacillin	`antibioticmech:chebi-1162e9b95e`	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.

beta-lactam sensitive penicillin-binding protein PROTEIN DIRECT_BINDING_TARGET

ARO:3000749

CARD/ARO database assertion; target organism, strain, and assay are not specified. Penicillin-binding proteins are asserted as inhibited transpeptidases. Evidence status: PRIMARY_EVIDENCE_NEEDED. Source: CARD_ARO 2026-08-30 (retrieved 2026-08-30).

ARO:3000749 (CARD/ARO asserts targeted_by_antibiotic ARO:0000056 (oxacillin); database assertion, not a primary citation.)

Activity spectrum

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

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

Activity observations
Organism	Activity	MIC	Disk diffusion	Assay	Strain	Sample/genome	Evidence
Staphylococcus aureus NCBITaxon:1280	—	16.0 mg/L	—	In-house reference broth microdilution oxacillin MIC; modal MIC from at least three tests; interpreted using CLSI M100 28th ed.	AR-0978	—	Evidence Page data (JSON.gz)
Staphylococcus aureus NCBITaxon:1280	—	8.0 mg/L	—	In-house reference broth microdilution oxacillin MIC; modal MIC from at least three tests; interpreted using CLSI M100 28th ed.	AR-0979	—	Evidence Page data (JSON.gz)
Staphylococcus aureus NCBITaxon:1280	—	16.0 mg/L	—	In-house reference broth microdilution oxacillin MIC; modal MIC from at least three tests; interpreted using CLSI M100 28th ed.	AR-0997	—	Evidence Page data (JSON.gz)
Staphylococcus aureus NCBITaxon:1280	—	>16.0 mg/L	—	Broth microdilution oxacillin MIC; modal MIC reported; interpreted using CLSI 2025 M100 S35.	0701	BioSample SAMN11953851	Evidence Page data (JSON.gz)
Staphylococcus aureus NCBITaxon:1280	—	>16.0 mg/L	—	Broth microdilution oxacillin MIC; modal MIC reported; interpreted using CLSI 2025 M100 S35.	0702	BioSample SAMN11953852	Evidence Page data (JSON.gz)
Staphylococcus epidermidis NCBITaxon:1282	—	>16.0 mg/L	—	Broth microdilution oxacillin MIC; modal MIC reported; interpreted using CLSI 2025 M100 S35.	0726	BioSample SAMN11953876	Evidence Page data (JSON.gz)
Staphylococcus haemolyticus NCBITaxon:1283	—	>16.0 mg/L	—	Broth microdilution oxacillin MIC; modal MIC reported; interpreted using CLSI 2025 M100 S35.	0729	BioSample SAMN11953879	Evidence Page data (JSON.gz)
Staphylococcus haemolyticus NCBITaxon:1283	—	>16.0 mg/L	—	Broth microdilution oxacillin MIC; modal MIC reported; interpreted using CLSI 2025 M100 S35.	0730	BioSample SAMN11953880	Evidence Page data (JSON.gz)

Resistance mechanisms

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

ANTIBIOTIC_EFFLUX 3

ANTIBIOTIC_EFFLUX
Determinant	ARO ID	Organism	Gene families	Evidence
Corynebacterium striatum tetA	ARO:3004639	not organism-specific	—	ARO:3004639 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:0000056 (oxacillin); database assertion, not a primary citation.)
MdtEF-TolC	ARO:3000788	not organism-specific	—	ARO:3000788 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:0000056 (oxacillin); database assertion, not a primary citation.)
mdeA	ARO:3007011	not organism-specific	—	ARO:3007011 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:0000056 (oxacillin); database assertion, not a primary citation.)

ANTIBIOTIC_INACTIVATION 2

ANTIBIOTIC_INACTIVATION
Determinant	ARO ID	Organism	Gene families	Evidence
OXA beta-lactamase	ARO:3000017	not organism-specific	—	ARO:3000017 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:0000056 (oxacillin); database assertion, not a primary citation.)
blaS1	ARO:3005111	not organism-specific	—	ARO:3005111 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:0000056 (oxacillin); database assertion, not a primary citation.)

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 2026-09-10 · seed_from_sources
Re-seeded from updated data/raw/ inventories
CURATED_RESISTANT_TAXA 2026-09-12 · codex · LLM-assisted
Added three DOI-backed oxacillin-resistant Staphylococcus aureus isolate MIC observations from Gargis et al. 2020.
CURATED_RESISTANT_TAXA 2026-09-13 · codex · LLM-assisted
Added five stable-URL CDC/FDA AR Isolate Bank Panel 1125 oxacillin-resistant Staphylococcus MIC observations for AR-0701, AR-0702, AR-0726, AR-0729, and AR-0730.
STRUCTURED_ACTIVITY_BIOSAMPLE_ACCESSIONS 2026-09-26 · codex · LLM-assisted
Structured BioSample accessions on 5 activity_spectrum observation(s) where evidence notes already named exactly one accession.

Provenance

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

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