Table 1

β-Lactamases expressed in this study

B-lactamaseAmbler classHydrolysis antibioticsHost(s) most frequently encounteredReference(s)Oligonucleotide sequences used for cloning (5′ → 3′)a
TEM-1APenicillins, early cephalosporinsEscherichia coli8, 12F, ggatccATGAGTATTCAACATTTTCGTGTC; R, gaattcTTACCAATGCTTAATCAGTGAGG
TEM-29AESBLbE. coli and Klebsiella pneumoniae8, 12F, ggatccATGAGTATTCAACATTTCCGTGT; R, gaattcTTACCAATGCTTAATCAGTGAGG
CTX-M-32 (cluster 1)AESBL (100-fold more active against ceftazidime than the other CTX-Ms)Enterobacteriaceae15, 24, 35F, ggatccATGGTTAAAAAATCACTGCGTCA; R, gaattcTTACAAACCGTTGGTGACGAT
CTX-M-8 (cluster 8)AESBLEnterobacteriaceae6, 24, 35F, ggatccATGATGAGACATCGCGTTAAG; R, gaattcTTAATAACCGTCGGTGACGAT
CTX-M-2 (cluster 2)AESBLEnterobacteriaceae24, 35; this workF, ggatccATGATGACTCAGAGCATTCG; R, gaattcTCAGAAACCGTGGGTTACG
CTX-M-14 (cluster 9)AESBLEnterobacteriaceae7, 24, 35F, ggatccATGGTGACAAAGAGAGTGCAA; R, gaattcTTACAGCCCTTCGGCGAT
SFO-1AESBLEnterobacter cloacae16, 28F, ggatccATGGTTAAAAATACATTACGTCAAAC; R, gaattcTCAAAGCCCTTCGGTGACAA
AmpR-SFO-1AESBLEnterobacter cloacae16, 28F, ggatccCTACGTATTATCTTCTGCCGC; R, gaattcTCAAAGCCCTTCGGTGACAA
VIM-1BMost β-lactams, except aztreonam, including carbapenemsPseudomonas, Enterobacteriaceae30, 45F, ggatccATGTTAAAAGTTATTAGTAGTTTATTGG R, gaattcCTACTCGGCGACTGAGC
FOX-4CPenicillins, narrow-, expanded-, and broad-spectrum cephalosporins, including cephamycinsEnterobacteriaceae10, 20, 26F, ggatccATGCAACAACGACGTGCG; R, gaattcTCACTCGGCCAACTGACTC
OXA-10-likeDOxacillin, cloxacillinPseudomonas aeruginosa12; this workF, ggatccATGAAAACATTTGCCGCATATGTA; R, gaattcTTAGCCACCAATGATGCCCT
OXA-24DOxacillin, cloxacillin, carbapenemsAcinetobacter baumannii9, 29F, ggatccATGAAAAAATTTATACTTCCTATATTCA; R, gaattcTTAAATGATTCCAAGATTTTCTAGCG
  • a F, forward; R, reverse. Lowercase indicates target site for restriction enzymes.

  • b ESBL, hydrolysis profile that confers resistance to the penicillins, broad-spectrum cephalosporins, and monobactams but not the cephamycins or carbapenems.