Phenotypic and genomic antibiogram of NDM isolatesa

Drug classDrugAST method and callECO-222ECO-165ECC-174ECO-190ECO-219
Beta-lactamsAztreonamKB resistanceRSRRR
CefoxitinMIC (μg/ml), resistance64, R64, R64, R64, R64, R
CeftriaxoneKB resistanceRRRRR
CefepimeKB resistanceRRRRR
ErtapenemKB resistanceRRRRR
ImipenemKB resistanceRRRIR
MeropenemKB resistanceRRRRR
All beta-lactamsGenotypeblaTEM-1 blaCTX-M-15 blaNDM-5 blaOXA-1blaTEM-1 (2 copies) blaNDM-5blaACT25 blaTEM-1 blaSHV-7 blaSHV-12 (2 copies) blaNDM-1blaCTX-M-15 blaCMY-6 blaTEM-1b blaOXA-1 blaNDM-1blaCTX-M-15 blaTEM-1 blaOXA-1 blaNDM-5
GlycylcyclinesTigecyclinebEtest (μg/ml)0.250.750.750.1250.38
TetracyclinesTetracyclineKB resistanceRNot doneNot doneNot doneS
TetracyclineMIC (μg/ml), resistanceNot done16, R4, S2, SNot done
All tetracyclinesGenotypetetB tetDtetANone detectedNone detectedNone detected
AminoglycosidesGentamicinMIC (μg/ml), resistance16, R4, R16, R16, R16, R
All aminoglycosidesGenotypeaac(3)-Id aac(6′)-Ib-cr ant(3″)-Ia (2 copies)rmtB aac(6′)Ib-cr ant(3″)-Ia family aph(3″) family aph(6)-I family aac(3)-Idaph(3′)-Ia ant(3″) family ant(3″)-Ia aph(6)-Id aph(3″) family ant(2″)-Ia aac(6)-IbrmtC aph(6)-Id aph(3″)-Ib aac(6′)Ib-cr aph(3′)-Ia aph(3′)-VIrmtB ant(3)-Ia aac(6′)-Ib-cr
Folate antagonistsTrimethoprim-sulfamethoxazoleMIC (μg/ml), resistance16/304, R16/304, R16/304, R16/304, R16/304, R
All folate antagonistsGenotypesul1 (2 copies) dfrA17 dfrA12sul1 sul2 dfrA14 (2 copies)sul1 (3 copies) dfrA8 dfrA19sul1 sul2 dfrA14sul1 dfrA12
FluoroquinolonesCiprofloxacinMIC (μg/ml), resistance4, R64, R4, R4, R4, R
All fluoroquinolonesGenotypeaac(6′)Ib-cr qnrS1aac(6′)Ib-crqnrS1 qnrB2aac(6′)Ib-cr qnrB1aac(6′)-Ib-cr
PhenicolChloramphenicolKB resistanceIRRRI
All phenicolsGenotypeNone detectedcatA1catA1cm/familyNone detected
PolymyxinsColistincMIC (μg/ml) resistance0.06 wild type0.06 wild type0.06 wild type0.12 wild type0.12 wild type
All polymyxinsGenotypeNone detectedNone detectedNone detectedNone detectedNone detected
  • a AST, antimicrobial susceptibility testing method; KB, Kirby-Bauer disk diffusion testing. MICs are by concentration cutoff for growth. Genotype indicates resistance genes identified by next-generation sequencing and gene annotation. R, resistant; I, intermediate; S, susceptible.

  • b Tigecycline Etest does not have CLSI guidelines for reporting resistance or susceptibility.

  • c Colistin MICs were assessed by broth microdilution as described in the CLSI guidelines (M100-ED28 [37]). Results are reported as epidemiological cutoff values (ECVs).