Browse AMR Genes

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mecI

mecC-type methicillin resistance repressor MecI

NCBI Pathogen Isolates

Bacterial genomes carrying this gene

NCBI Reference Gene Catalog

Known alleles and reference sequences

Protein entries specific to mecI

Browse AMR rules for mecI

Validation StatusConfirmed2+ DBs

Overview

Mechanism: antibiotic target replacement
Validation Method: sequencing and transformation experiments
Drug Classes: METHICILLIN, Oxacillin, Methicillin, Penicillin, Beta-lactams
Organisms: Staphylococcus aureus subsp. aureus LGA251, Staphylococcus aureus, Staphylococcus aureus M0039, Staphylococcus aureus ATCC BAA-39, E. coli ATCC BAA-196, Macrococcus caseolyticus, Staphylococcus aureus Guangzhou-SAU749, Staphylococcus epidermidis, Staphylococcus aureus subsp. aureus str. JKD6008, Staphylococcus aureus subsp. aureus N315
Geographic Location: Benin, China, Europe|USA, Iran|Saudi Arabia, Khartoum State, Sudan +2 more
Alleles: 2
Papers: 12
Databases: Card DatabaseReference Gene CatalogReslit
Mutations: 15

Mutations

Protein Change	Nucleotide Change	Mechanism	Organism	Resistance To	Database	Validation Status
L116S	-	-	Staphylococcus aureus	Oxacillin	Reslit	Candidate
L52*	-	-	Staphylococcus aureus	Oxacillin	Reslit	Candidate
Q68*	-	-	Staphylococcus aureus	Oxacillin	Reslit

Allele Variants2

Allele	Database	Papers	Drug Classes	Organisms	Countries	Years	Sequence Accession	Protein Accession
MecI	Card DatabaseReference Gene CatalogReslit	13	METHICILLIN, Oxacillin +3	Staphylococcus aureus subsp. aureus LGA251 +8	global, Iran\|Saudi Arabia, Khartoum State, Sudan, Benin, China, Shanghai, China, Europe\|USA	2011, 2014, 2020, 2021, 2022, 2023, 2025	FR821779.1	CCC86797.1
mecI	Card Database	1	-	Staphylococcus aureus subsp. aureus N315	-	-	BA000018.3	BAB41258.1

Papers12

1

Meticillin-resistant Staphylococcus aureus with a novel mecA homologue in human and bovine populations in the UK and Denmark: a descriptive study.

PMID 21641281 · 2011

Gene Information

Gene Name: mecI
Allele: MecI
Encodes: mecC-type methicillin resistance repressor MecI
Source Database: Card Database
Mechanism: antibiotic target replacement
Confers Resistance To: METHICILLIN
Organisms Tested In: • Staphylococcus aureus subsp. aureus LGA251
Sequence Accession: FR821779.1
Protein Accession: CCC86797.1
Notes: ARO:3005046

2

Meticillin-resistant Staphylococcus aureus with a novel mecA homologue in human and bovine populations in the UK and Denmark: a descriptive study.

PMID 21641281 · 2011

Gene Information

Gene Name: mecI
Allele: MecI
Encodes: mecC-type methicillin resistance repressor MecI
Source Database: Reference Gene Catalog
Mechanism: antibiotic target replacement
Confers Resistance To: METHICILLIN
Organisms Tested In: • Staphylococcus aureus subsp. aureus LGA251
Sequence Accession: FR821779.1
Protein Accession: CCC86797.1
Notes: ARO:3005046

3

Methicillin-resistance in Staphylococcus aureus is not affected by the overexpression in trans of the mecA gene repressor: a surprising observation.

PMID 21829724 · 2011

The study shows that overexpression of mecI does not significantly alter oxacillin resistance levels in most MRSA strains, indicating that other factors may influence mecA regulation and β-lactam resistance.

Gene Information

Gene Name: mecI
Allele: MecI
Encodes: repressor protein
Source Database: Reslit
Confers Resistance To: Oxacillin
Organisms Tested In: • Staphylococcus aureus
Geographic Location: global
Validation Method: sequencing and transformation experiments
Sequence Accession: NCBI:CP000046|NCBI:CP000047|NCBI:CP000048

4

Regulation of the expression of the β-lactam antibiotic-resistance determinants in methicillin-resistant Staphylococcus aureus (MRSA).

PMID 24564530 · 2014

Gene Information

Gene Name: mecI
Allele: MecI
Encodes: mecA-type methicillin resistance repressor MecI
Source Database: Card Database
Mechanism: antibiotic target replacement
Confers Resistance To: METHICILLIN
Organisms Tested In: • Staphylococcus aureus M0039
Sequence Accession: JBTS01000004.1
Protein Accession: EUK27095.1
Notes: ARO:3000124

5

Regulation of the expression of the β-lactam antibiotic-resistance determinants in methicillin-resistant Staphylococcus aureus (MRSA).

PMID 24564530 · 2014

Gene Information

Gene Name: mecI
Allele: MecI
Encodes: mecA-type methicillin resistance repressor MecI
Source Database: Reference Gene Catalog
Mechanism: antibiotic target replacement
Confers Resistance To: METHICILLIN
Organisms Tested In: • Staphylococcus aureus M0039
Sequence Accession: JBTS01000004.1
Protein Accession: EUK27095.1
Notes: ARO:3000124

6

The Effect of Iodine-Containing Nano-Micelles, FS-1, on Antibiotic Resistance, Gene Expression and Epigenetic Modifications in the Genome of Multidrug Resistant MRSA Strain Staphylococcus aureus ATCC BAA-39.

PMID 33193215 · 2020

The study shows that FS-1 induces antibiotic resistance reversion in MRSA strain S. aureus ATCC BAA-39, with significant reductions in methicillin resistance and changes in gene expression patterns. The SCC mec cassette, containing mecA and mecR, showed decreased coverage in both NC and FS genomes.

Gene Information

Gene Name: mecI
Allele: MecI
Encodes: methicillin resistance repressor
Source Database: Reslit
Confers Resistance To: Methicillin
Organisms Tested In: • Staphylococcus aureus ATCC BAA-39
• E. coli ATCC BAA-196
Validation Method: gene expression and susceptibility testing
Sequence Accession: SRX5852332|SRX5843551|SRR10728551|SRR10728552|SRR10728553|SRR10728554|CP033505.1|CP033506.1

7

Regulation of virulence and β-lactamase gene expression in Staphylococcus aureus isolates: cooperation of two-component systems in bloodstream superbugs.

PMID 34172010 · 2021

The study characterizes the molecular relationships between two-component systems of virulence factors and the expression of the β-lactamase gene in MRSA-BSI isolates, highlighting the role of genes such as mecA, blaZ, mecI, mecRI, sarA, RNAIII, and SaeRS in β-lactam resistance.

Gene Information

Gene Name: mecI
Allele: MecI
Encodes: repressor of mecA
Source Database: Reslit
Confers Resistance To: Penicillin
Organisms Tested In: • Staphylococcus aureus
Geographic Location: Iran|Saudi Arabia
Validation Method: q-RT PCR

8

A prevalence and molecular characterization of novel pathogenic strains of Macrococcus caseolyticus isolated from external wounds of donkeys in Khartoum State -Sudan.

PMID 35614464 · 2022

The study identified a novel strain of Macrococcus caseolyticus, DaniaSudan, which exhibits resistance to several antibiotics, including ciprofloxacin, ceftazidime, erythromycin, oxacillin, clindamycin, and kanamycin. The strain was found to possess resistance genes such as ANT(4')-Ib, mecA, mecI, mecR1, and Tet(38).

Gene Information

Gene Name: mecI
Allele: MecI
Encodes: transcriptional repressor
Source Database: Reslit
Mechanism: regulates mecA expression
Confers Resistance To: Oxacillin
Organisms Tested In: • Macrococcus caseolyticus
Geographic Location: Khartoum State, Sudan
Validation Method: whole-genome sequencing and RAST annotation
Sequence Accession: RBVL00000000

9

Whole-Genome Sequencing-Based Screening of MRSA in Patients and Healthcare Workers in Public Hospitals in Benin.

PMID 37630513 · 2023

The study identified multiple AMR genes and mutations in MRSA isolates from Benin, including mecA, aac(6')-Ie/aph(2")-Ia, aph(3')-IIIa, blaI, blaR1, blaZ, mecI, mecR1, fosB, erm(C), mph(C), msr(A), qacC, dfrG, and dfrS1, along with mutations in glpT, murA, gyrA, and parC associated with resistance to various antibiotics.

Gene Information

Gene Name: mecI
Allele: MecI
Encodes: beta-lactam resistance
Source Database: Reslit
Confers Resistance To: Beta-lactams
Organisms Tested In: • Staphylococcus aureus
Geographic Location: Benin
Validation Method: whole-genome sequencing

10

Sub-MIC streptomycin and tetracycline enhanced Staphylococcus aureus Guangzhou-SAU749 biofilm formation, an in-depth study on transcriptomics.

PMID 37779859 · 2023

The study identified several AMR genes in S. aureus Guangzhou-SAU749, including ermB, mecA, mecR1, mepA, aad(6), tet(38), and others. These genes were associated with resistance to various antibiotics. Additionally, the study found that sub-MIC concentrations of streptomycin and tetracycline enhanced biofilm formation, which was linked to the regulation of genes such as arlR, hssR, tagA, clfB, and atlA.

Gene Information

Gene Name: mecI
Allele: MecI
Encodes: Beta-lactam resistance
Source Database: Reslit
Confers Resistance To: Penicillin
Organisms Tested In: • Staphylococcus aureus Guangzhou-SAU749
Geographic Location: China
Validation Method: Database prediction (CARD)
Sequence Accession: CP053185|CP053186

11

Metagenomic identification of pathogens and antimicrobial-resistant genes in bacterial positive blood cultures by nanopore sequencing.

PMID 38192400 · 2023

The study identified various antimicrobial resistance (AMR) genes in bacterial positive blood cultures using nanopore sequencing, demonstrating the effectiveness of this method in detecting resistance mechanisms and pathogens quickly.

Gene Information

Gene Name: mecI
Allele: MecI
Encodes: repressor of mecA
Source Database: Reslit
Confers Resistance To: Penicillin
Organisms Tested In: • Staphylococcus aureus
Geographic Location: Shanghai, China
Validation Method: comparison with phenotypic antimicrobial susceptibility testing
Sequence Accession: OEP004528

12

Staphylococcus epidermidis in Acute Myeloid Leukemia: A Comparative Genomic Study Against Non-AML Isolates.

PMID 40732675 · 2025

The study identified several AMR genes in S. epidermidis isolates from AML patients, including mecA, mecR1, qacA, ermC, tetM, cfrA, ANT(4′)-Ib, blaZ, dfrG, cat, and mecI, which were associated with increased resistance to various antibiotics.

Gene Information

Gene Name: mecI
Allele: MecI
Encodes: transcriptional repressor of mecA
Source Database: Reslit
Mechanism: represses mecA-mediated beta-lactam resistance
Confers Resistance To: Beta-lactams
Organisms Tested In: • Staphylococcus epidermidis
Geographic Location: Europe|USA
Validation Method: genomic analysis
Sequence Accession: PRJNA1262472

13

Gene Information

Gene Name: mecI
Allele: MecI
Encodes: mecA-type methicillin resistance repressor MecI
Source Database: Reference Gene Catalog
Confers Resistance To: METHICILLIN
Organisms Tested In: • Staphylococcus aureus subsp. aureus str. JKD6008
Sequence Accession: CP002120.1
Protein Accession: ADL64127.1

14

Gene Information

Gene Name: mecI
Allele: mecI
Encodes: methicillin resistant PBP2
Source Database: Card Database
Mechanism: antibiotic target replacement
Organisms Tested In: • Staphylococcus aureus subsp. aureus N315
Sequence Accession: BA000018.3
Protein Accession: BAB41258.1
Notes: ARO:3000124