TABLE 1

Staphylococcus strain characteristics and origins and MICs of β-lactam antibiotics

Strain/plasmidOrigin and characteristicsReference or sourceMIC (µg/ml)Nitrocefin test result
PenicillinAmpicillinCefoxitinMeropenem
S. aureus
    RN4220Plasmid-free recipient25≤0.125≤0.1220.06Negative
    RN4220/pBUS1-Pcap-HCRN4220 containing expression vector pBUS1-Pcap-HC17≤0.125≤0.1220.06Negative
    RN4220/pTSSCmRN4220 containing cloning vector pTSSCm17≤0.125≤0.1220.06Negative
    RN4220/pSAN01RN4220 harboring pTSSCm with blaIARL-blaR1ARL-blaARL operonThis study0.25≤0.1220.06Positive
    RN4220/pSAN02mutRN4220 harboring pBUS1-Pcap-HC with blaARL gene under control of Pcap promoterThis study20.540.12Positive
S. arlettae
    SAN1670Bovine mastitis milk, Switzerland, 2010This study0.50.540.5Positive
    SAN2677Bovine mastitis milk, Switzerland, 2015This study0.250.540.25Positive
    SAN2690Bovine mastitis milk, Switzerland, 2015This study0.250.540.25Positive
    SAN1988Bovine mastitis milk, Switzerland, 2016This study0.50.2520.25Positive
    SAN2420Bovine mastitis milk, Switzerland, 2016This study0.50.520.5Negative
    BM242Bovine mastitis milk, Switzerland, 2016This study/Agroscope0.250.540.5Positive
    CSKR33Equine skin, Switzerland, 200420.5120.25Positive
    CCUG 33610Tobacco fermentation process, Sweden, 1994CCUG, 19940.250.2540.25Positive
    CCUG 50677Tobacco, Sweden, 2005CCUG, 20050.250.520.25Positive
    CCUG 32416 TPoultry skin, Belgium, 198410.250.2520.25Positive
    ILRI338Camel nasal cavity, Kenya, 2014This study/ILRI0.250.2540.25Positive