Skip to main content

Table 2 Antimicrobial resistance genomic signatures against phenotypic antimicrobial resistance profiles. In the 71 strains for which the Minimum inhibitory concentration (MIC) data for Meropenem (MEM), Ceftazidime/Avibactam (CZA), Colistin (CST), and Trimethoprim/Sulfamethoxazole (SXT) were available, differences in the phenotypic antimicrobial resistance were evaluated according to blaKPC gene variants, colistin mutations, presence of genes associated with trimethoprim and sulfonamide resistance, number of Tn4401a copies and porin mutations. Only one strain (29_II, carrying both KPC-2 and NDM-1) was found resistant (MIC: 16 µg/ml) to the Meropenem/Vaborbactam (MEM/VAB) combination

From: Genomic characterization of Klebsiella pneumoniae carbapenemase-producing Klebsiella pneumoniae (KPC-Kp) strains circulating in three university hospitals in Northern Italy over three years

Mechanism

Meropenem

Ceftazidime/Avibactam

Colistin

Trimethoprim/sulfamethoxazole

(MEM)

(CZA)

(CST)

(SXT)

MIC breakpoint for resistance >8 N(%)a

MIC Median (IQR)b

p-valuec

MIC breakpoint for resistance >8 N(%)a

MIC Median (IQR)b

p-valuec

MIC breakpoint for resistance >2 N(%)a

MIC Median (IQR)b

p-valuec

MIC breakpoint for resistance >4 N(%)a

MIC Median (IQR)b

p-valuec

blaKPCgened

blaKPC-2  N=29

25 (86.2)

16 (16-32)

1) 0.368 2) 0.914

0 (0.0)

2 (1-2)

1) 1.000 2) 0.002

-

-

-

-

-

-

blaKPC-3  N=41

31 (75.6)

16 (16-32)

1 (2.4)

2 (2-2)

-

-

-

-

Porin mutations

none N=44

31 (70.5)

16 (8-16)

1) 0.036 2) <0.001

1 (2.3)

2 (2-2)

1) 1.00 2) 0.002

-

-

-

-

-

-

At least one N=27

25 (92.6)

32 (32-32)

1 (3.7)

2 (2-4)

-

-

-

-

Tn4401 copies

1 N=65

50 (76.9)

16 (16-32)

1) 0.331 2) 0.006

2 (3.1)

2 (2-2)

1) 1.000 2) 0.001

-

-

-

-

-

-

> 1 N=6

6 (100)

32 (32-32)

0 (0.0)

6 (4-8)

-

-

-

-

1 Tn4401copy and no porin mutations N=44

31 (70.5)

16 (8-16)

1) 0.026 2) <0.001

1 (2.3)

2 (2-2)

1) 0.938 2) <0.001

-

-

-

-

-

-

1 Tn4401copy and at least 1 porin mutation N=21

19 (90.5)

32 (32-32)

1 (4.8)

2 (2-2)

-

-

-

-

>1 Tn4401copy and at least 1 porin mutation N=6

6 (100.0)

32 (32-32)

0 (0.0)

6 (4-8)

-

-

-

-

Colistin mutations

none N=51

-

-

-

-

-

-

1 (2.0)

2 (0.5-2)

1) <0.001 2) 0.001

-

-

-

MgrB or PmrB N=20

-

-

-

-

7 (35.0)

2 (2-4)

-

-

Trimethoprim and sulfonamide mutations

none N=21

-

-

-

-

-

-

-

-

-

0 (0.0)

2 (2-4)

1) 0.027 2) <0.001

dfrA or sul N=50

-

-

-

-

-

-

11 (22.0)

4 (4-4)

  1. aClinical Minimum Inhibitory Concentration (MIC) breakpoint for resistance according to “The European Committee on Antimicrobial Susceptibility Testing. Breakpoint tables for interpretation of MICs and zone diameters. Version 14.0, 2024. http://www.eucast.org."
  2. bMedian and interquartile range (IQR) of MIC values (in µg/ml) for each of the antibiotics reported
  3. cTwo-sided p-values were calculated by 1) Fisher exact test and Chi-square for trend, for comparison of categorical variables among two and three independent groups, respectively, and 2) Kruskal–Wallis and Mann-Whitney tests for comparison of continuous variables among two or three groups, respectively
  4. dblaKPC-33 (N=1) is not included
Back to article page

Antimicrobial Resistance & Infection Control

ISSN: 2047-2994

Contact us