Ambler class C-type β-lactamases and porin alterations in Enterobacter cloacae complex and Klebsiella aerogenes in the Netherlands, 2012-2023

Elke van Gorp; Simon Lansu; Cornelia C H Wielders; Angela de Haan; Gert-Jan Godeke; Sandra Witteveen; Jeroen Bos; Fabian Landman; Maureen Ouw; Herman F Wunderink; M P A van Meer; Wil van der Zwet; Daan W Notermans; Antoni P A Hendrickx; A L E van Arkel; M A Leversteijn-van Hall; W van den Bijllaardt; R van Mansfeld; K van Dijk; B Zwart; B M W Diederen; H Berkhout; A Ott; K Waar; W Ang; J da Silva; A L M Vlek; J J J M Stohr; L G M Bode; A Jansz; S Paltansing; A J van Griethuysen; J R Lo Ten Foe; M J C A van Trijp; M Wong; A E Muller; M P M van der Linden; M van Rijn; S B Debast; E Kolwijck; N Al Naiemi; T Schulin; S Dinant; S P van Mens; D C Melles; J W T Cohen Stuart; P Gruteke; A P van Dam; I Maat; B Maraha; J C Sinnige; E van der Vorm; M P A van Meer; M de Graaf; E de Jong; S J Vainio; E Heikens; M den Reijer; J W Dorigo-Zetsma; A Troelstra; E Bathoorn; J de Vries; D W van Dam; E I G B de Brauwer; R Steingrover; F Koene; C Oliveira Dos Santos

doi:10.1186/s12866-026-04741-1

Ambler class C-type β-lactamases and porin alterations in Enterobacter cloacae complex and Klebsiella aerogenes in the Netherlands, 2012-2023

Elke van Gorp
, Simon Lansu
, Cornelia C H Wielders
, Angela de Haan
, Gert-Jan Godeke
, Sandra Witteveen
, Jeroen Bos
, Fabian Landman
, Maureen Ouw
, Herman F Wunderink
, M P A van Meer
, Wil van der Zwet
, Daan W Notermans
, Antoni P A Hendrickx^*
, A L E van Arkel
, M A Leversteijn-van Hall
, W van den Bijllaardt
, R van Mansfeld
, K van Dijk
, B Zwart

B M W Diederen, H Berkhout, A Ott, K Waar, W Ang, J da Silva, A L M Vlek, J J J M Stohr, L G M Bode, A Jansz, S Paltansing, A J van Griethuysen, J R Lo Ten Foe, M J C A van Trijp, M Wong, A E Muller, M P M van der Linden, M van Rijn, S B Debast, E Kolwijck, N Al Naiemi, T Schulin, S Dinant, S P van Mens, D C Melles, J W T Cohen Stuart, P Gruteke, A P van Dam, I Maat, B Maraha, J C Sinnige, E van der Vorm, M P A van Meer, M de Graaf, E de Jong, S J Vainio, E Heikens, M den Reijer, J W Dorigo-Zetsma, A Troelstra, E Bathoorn, J de Vries, D W van Dam, E I G B de Brauwer, R Steingrover, F Koene, C Oliveira Dos Santos

^*Corresponding author for this work

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Abstract

We investigated the genomic epidemiology of Ambler class C (AmpC-type) β-lactamases in Enterobacter cloacae complex and Klebsiella aerogenes in the national carbapenemase-producing Enterobacterales (CPE) surveillance of the Netherlands between 2012 and 2023. A total of 399 E. cloacae complex and K. aerogenes isolates from 399 patients were analyzed using whole-genome sequencing to assess genetic relatedness, resistance genes, porin, and AmpC-regulatory gene profiles, plasmid replicons, and the genomic location of AmpC-genes, respectively. Of the 399 patients, 217 were male (54%), and the median age was 67 years. Carbapenemase production was assessed using the carbapenem inactivation method (CIM) and CarbaNP-test. A considerable proportion of E. cloacae complex (32%) and K. aerogenes (52%) isolates were CIM-positive in the absence of detectable carbapenemase genes (IMP, KPC, NDM, OXA-48-like, VIM) by the CarbaPCR, a phenotype termed CIM + Carba-. These isolates were mostly (81.9%) susceptible (EUCAST ≤ 2mg/L) to meropenem. The majority of CIM + Carba + isolates with major carbapenemase genes were gained from pre-emptive screening, while CIM + Carba- isolates were mainly taken for diagnostic purposes. Genomic analysis identified 18 genogroups, with E. kobei, E. roggenkampii, E. ludwigii, and K. aerogenes showing the CIM + Carba- phenotype, were mostly lacking porins and AmpC regulators, and correlated with chromosome-encoded AmpC-type β-lactamases like blaACT-28, blaACT-52, blaMIR-3, blaMIR-11 or ampC of which the majority (63%) yielded a positive CarbaNP-test. These CIM + Carba- isolates carried only few plasmids, and there was limited evidence of nosocomial spread. CIM + Carba- E. kobei carrying blaACT-28 overproduced ACT-28 protein in the CIM. Overall, the Enterobacter and K. aerogenes population in the Netherlands is genetically diverse, with most isolates carrying species-specific AmpC-type β-lactamases. Isolates with low MIC for meropenem that lack porins and major carbapenemases represent a low-risk for public health.

Original language	English
Article number	192
Journal	BMC Microbiology
Volume	26
Issue number	1
Early online date	30 Jan 2026
DOIs	https://doi.org/10.1186/s12866-026-04741-1
Publication status	Published - 2 Mar 2026

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Ambler class C-type β-lactamases and porin alterations in Enterobacter cloacae complex and Klebsiella aerogenes in the Netherlands, 2012–2023Final published version, 4.37 MBLicence: CC BY-NC-ND

1 Comment/Letter to the editor

Correction: Ambler class C-type β-lactamases and porin alterations in Enterobacter cloacae complex and Klebsiella aerogenes in the Netherlands, 2012–2023 (BMC Microbiology, (2026), 26, 1, (192), 10.1186/s12866-026-04741-1)
The Dutch CPE surveillance Study Group, 28 Mar 2026, In: BMC Microbiology. 26, 1, 284.
Research output: Contribution to journal › Comment/Letter to the editor › Academic › peer-review

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van Gorp, E., Lansu, S., Wielders, C. C. H., de Haan, A., Godeke, G.-J., Witteveen, S., Bos, J., Landman, F., Ouw, M., Wunderink, H. F., van Meer, M. P. A., van der Zwet, W., Notermans, D. W., Hendrickx, A. P. A., van Arkel, A. L. E., Leversteijn-van Hall, M. A., van den Bijllaardt, W., van Mansfeld, R., van Dijk, K., ... Oliveira Dos Santos, C. (2026). Ambler class C-type β-lactamases and porin alterations in Enterobacter cloacae complex and Klebsiella aerogenes in the Netherlands, 2012-2023. BMC Microbiology, 26(1), Article 192. https://doi.org/10.1186/s12866-026-04741-1

@article{1a722973823e4112b4706d0f17178ad1,

title = "Ambler class C-type β-lactamases and porin alterations in Enterobacter cloacae complex and Klebsiella aerogenes in the Netherlands, 2012-2023",

abstract = "We investigated the genomic epidemiology of Ambler class C (AmpC-type) β-lactamases in Enterobacter cloacae complex and Klebsiella aerogenes in the national carbapenemase-producing Enterobacterales (CPE) surveillance of the Netherlands between 2012 and 2023. A total of 399 E. cloacae complex and K. aerogenes isolates from 399 patients were analyzed using whole-genome sequencing to assess genetic relatedness, resistance genes, porin, and AmpC-regulatory gene profiles, plasmid replicons, and the genomic location of AmpC-genes, respectively. Of the 399 patients, 217 were male (54\%), and the median age was 67 years. Carbapenemase production was assessed using the carbapenem inactivation method (CIM) and CarbaNP-test. A considerable proportion of E. cloacae complex (32\%) and K. aerogenes (52\%) isolates were CIM-positive in the absence of detectable carbapenemase genes (IMP, KPC, NDM, OXA-48-like, VIM) by the CarbaPCR, a phenotype termed CIM + Carba-. These isolates were mostly (81.9\%) susceptible (EUCAST ≤ 2mg/L) to meropenem. The majority of CIM + Carba + isolates with major carbapenemase genes were gained from pre-emptive screening, while CIM + Carba- isolates were mainly taken for diagnostic purposes. Genomic analysis identified 18 genogroups, with E. kobei, E. roggenkampii, E. ludwigii, and K. aerogenes showing the CIM + Carba- phenotype, were mostly lacking porins and AmpC regulators, and correlated with chromosome-encoded AmpC-type β-lactamases like blaACT-28, blaACT-52, blaMIR-3, blaMIR-11 or ampC of which the majority (63\%) yielded a positive CarbaNP-test. These CIM + Carba- isolates carried only few plasmids, and there was limited evidence of nosocomial spread. CIM + Carba- E. kobei carrying blaACT-28 overproduced ACT-28 protein in the CIM. Overall, the Enterobacter and K. aerogenes population in the Netherlands is genetically diverse, with most isolates carrying species-specific AmpC-type β-lactamases. Isolates with low MIC for meropenem that lack porins and major carbapenemases represent a low-risk for public health.",

author = "\{van Gorp\}, Elke and Simon Lansu and Wielders, \{Cornelia C H\} and \{de Haan\}, Angela and Gert-Jan Godeke and Sandra Witteveen and Jeroen Bos and Fabian Landman and Maureen Ouw and Wunderink, \{Herman F\} and \{van Meer\}, \{M P A\} and \{van der Zwet\}, Wil and Notermans, \{Daan W\} and Hendrickx, \{Antoni P A\} and \{van Arkel\}, \{A L E\} and \{Leversteijn-van Hall\}, \{M A\} and \{van den Bijllaardt\}, W and \{van Mansfeld\}, R and \{van Dijk\}, K and B Zwart and Diederen, \{B M W\} and H Berkhout and A Ott and K Waar and W Ang and \{da Silva\}, J and Vlek, \{A L M\} and Stohr, \{J J J M\} and Bode, \{L G M\} and A Jansz and S Paltansing and \{van Griethuysen\}, \{A J\} and \{Lo Ten Foe\}, \{J R\} and \{van Trijp\}, \{M J C A\} and M Wong and Muller, \{A E\} and \{van der Linden\}, \{M P M\} and \{van Rijn\}, M and Debast, \{S B\} and E Kolwijck and \{Al Naiemi\}, N and T Schulin and S Dinant and \{van Mens\}, \{S P\} and Melles, \{D C\} and Stuart, \{J W T Cohen\} and P Gruteke and \{van Dam\}, \{A P\} and I Maat and B Maraha and Sinnige, \{J C\} and \{van der Vorm\}, E and \{van Meer\}, \{M P A\} and \{de Graaf\}, M and \{de Jong\}, E and Vainio, \{S J\} and E Heikens and \{den Reijer\}, M and Dorigo-Zetsma, \{J W\} and A Troelstra and E Bathoorn and \{de Vries\}, J and \{van Dam\}, \{D W\} and \{de Brauwer\}, \{E I G B\} and R Steingrover and F Koene and \{Oliveira Dos Santos\}, C",

note = "Publisher Copyright: {\textcopyright} The Author(s) 2026.",

year = "2026",

month = mar,

day = "2",

doi = "10.1186/s12866-026-04741-1",

language = "English",

volume = "26",

journal = "BMC Microbiology",

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van Gorp, E, Lansu, S, Wielders, CCH, de Haan, A, Godeke, G-J, Witteveen, S, Bos, J, Landman, F, Ouw, M, Wunderink, HF, van Meer, MPA, van der Zwet, W, Notermans, DW, Hendrickx, APA, van Arkel, ALE, Leversteijn-van Hall, MA, van den Bijllaardt, W, van Mansfeld, R, van Dijk, K, Zwart, B, Diederen, BMW, Berkhout, H, Ott, A, Waar, K, Ang, W, da Silva, J, Vlek, ALM, Stohr, JJJM, Bode, LGM, Jansz, A, Paltansing, S, van Griethuysen, AJ, Lo Ten Foe, JR, van Trijp, MJCA, Wong, M, Muller, AE, van der Linden, MPM, van Rijn, M, Debast, SB, Kolwijck, E, Al Naiemi, N, Schulin, T, Dinant, S, van Mens, SP, Melles, DC, Stuart, JWTC, Gruteke, P, van Dam, AP, Maat, I, Maraha, B, Sinnige, JC, van der Vorm, E, van Meer, MPA, de Graaf, M, de Jong, E, Vainio, SJ, Heikens, E, den Reijer, M, Dorigo-Zetsma, JW, Troelstra, A, Bathoorn, E, de Vries, J, van Dam, DW, de Brauwer, EIGB, Steingrover, R, Koene, F & Oliveira Dos Santos, C 2026, 'Ambler class C-type β-lactamases and porin alterations in Enterobacter cloacae complex and Klebsiella aerogenes in the Netherlands, 2012-2023', BMC Microbiology, vol. 26, no. 1, 192. https://doi.org/10.1186/s12866-026-04741-1

TY - JOUR

T1 - Ambler class C-type β-lactamases and porin alterations in Enterobacter cloacae complex and Klebsiella aerogenes in the Netherlands, 2012-2023

AU - van Gorp, Elke

AU - Lansu, Simon

AU - Wielders, Cornelia C H

AU - de Haan, Angela

AU - Godeke, Gert-Jan

AU - Witteveen, Sandra

AU - Bos, Jeroen

AU - Landman, Fabian

AU - Ouw, Maureen

AU - Wunderink, Herman F

AU - van Meer, M P A

AU - van der Zwet, Wil

AU - Notermans, Daan W

AU - Hendrickx, Antoni P A

AU - van Arkel, A L E

AU - Leversteijn-van Hall, M A

AU - van den Bijllaardt, W

AU - van Mansfeld, R

AU - van Dijk, K

AU - Zwart, B

AU - Diederen, B M W

AU - Berkhout, H

AU - Ott, A

AU - Waar, K

AU - Ang, W

AU - da Silva, J

AU - Vlek, A L M

AU - Stohr, J J J M

AU - Bode, L G M

AU - Jansz, A

AU - Paltansing, S

AU - van Griethuysen, A J

AU - Lo Ten Foe, J R

AU - van Trijp, M J C A

AU - Wong, M

AU - Muller, A E

AU - van der Linden, M P M

AU - van Rijn, M

AU - Debast, S B

AU - Kolwijck, E

AU - Al Naiemi, N

AU - Schulin, T

AU - Dinant, S

AU - van Mens, S P

AU - Melles, D C

AU - Stuart, J W T Cohen

AU - Gruteke, P

AU - van Dam, A P

AU - Maat, I

AU - Maraha, B

AU - Sinnige, J C

AU - van der Vorm, E

AU - van Meer, M P A

AU - de Graaf, M

AU - de Jong, E

AU - Vainio, S J

AU - Heikens, E

AU - den Reijer, M

AU - Dorigo-Zetsma, J W

AU - Troelstra, A

AU - Bathoorn, E

AU - de Vries, J

AU - van Dam, D W

AU - de Brauwer, E I G B

AU - Steingrover, R

AU - Koene, F

AU - Oliveira Dos Santos, C

PY - 2026/3/2

Y1 - 2026/3/2

N2 - We investigated the genomic epidemiology of Ambler class C (AmpC-type) β-lactamases in Enterobacter cloacae complex and Klebsiella aerogenes in the national carbapenemase-producing Enterobacterales (CPE) surveillance of the Netherlands between 2012 and 2023. A total of 399 E. cloacae complex and K. aerogenes isolates from 399 patients were analyzed using whole-genome sequencing to assess genetic relatedness, resistance genes, porin, and AmpC-regulatory gene profiles, plasmid replicons, and the genomic location of AmpC-genes, respectively. Of the 399 patients, 217 were male (54%), and the median age was 67 years. Carbapenemase production was assessed using the carbapenem inactivation method (CIM) and CarbaNP-test. A considerable proportion of E. cloacae complex (32%) and K. aerogenes (52%) isolates were CIM-positive in the absence of detectable carbapenemase genes (IMP, KPC, NDM, OXA-48-like, VIM) by the CarbaPCR, a phenotype termed CIM + Carba-. These isolates were mostly (81.9%) susceptible (EUCAST ≤ 2mg/L) to meropenem. The majority of CIM + Carba + isolates with major carbapenemase genes were gained from pre-emptive screening, while CIM + Carba- isolates were mainly taken for diagnostic purposes. Genomic analysis identified 18 genogroups, with E. kobei, E. roggenkampii, E. ludwigii, and K. aerogenes showing the CIM + Carba- phenotype, were mostly lacking porins and AmpC regulators, and correlated with chromosome-encoded AmpC-type β-lactamases like blaACT-28, blaACT-52, blaMIR-3, blaMIR-11 or ampC of which the majority (63%) yielded a positive CarbaNP-test. These CIM + Carba- isolates carried only few plasmids, and there was limited evidence of nosocomial spread. CIM + Carba- E. kobei carrying blaACT-28 overproduced ACT-28 protein in the CIM. Overall, the Enterobacter and K. aerogenes population in the Netherlands is genetically diverse, with most isolates carrying species-specific AmpC-type β-lactamases. Isolates with low MIC for meropenem that lack porins and major carbapenemases represent a low-risk for public health.

AB - We investigated the genomic epidemiology of Ambler class C (AmpC-type) β-lactamases in Enterobacter cloacae complex and Klebsiella aerogenes in the national carbapenemase-producing Enterobacterales (CPE) surveillance of the Netherlands between 2012 and 2023. A total of 399 E. cloacae complex and K. aerogenes isolates from 399 patients were analyzed using whole-genome sequencing to assess genetic relatedness, resistance genes, porin, and AmpC-regulatory gene profiles, plasmid replicons, and the genomic location of AmpC-genes, respectively. Of the 399 patients, 217 were male (54%), and the median age was 67 years. Carbapenemase production was assessed using the carbapenem inactivation method (CIM) and CarbaNP-test. A considerable proportion of E. cloacae complex (32%) and K. aerogenes (52%) isolates were CIM-positive in the absence of detectable carbapenemase genes (IMP, KPC, NDM, OXA-48-like, VIM) by the CarbaPCR, a phenotype termed CIM + Carba-. These isolates were mostly (81.9%) susceptible (EUCAST ≤ 2mg/L) to meropenem. The majority of CIM + Carba + isolates with major carbapenemase genes were gained from pre-emptive screening, while CIM + Carba- isolates were mainly taken for diagnostic purposes. Genomic analysis identified 18 genogroups, with E. kobei, E. roggenkampii, E. ludwigii, and K. aerogenes showing the CIM + Carba- phenotype, were mostly lacking porins and AmpC regulators, and correlated with chromosome-encoded AmpC-type β-lactamases like blaACT-28, blaACT-52, blaMIR-3, blaMIR-11 or ampC of which the majority (63%) yielded a positive CarbaNP-test. These CIM + Carba- isolates carried only few plasmids, and there was limited evidence of nosocomial spread. CIM + Carba- E. kobei carrying blaACT-28 overproduced ACT-28 protein in the CIM. Overall, the Enterobacter and K. aerogenes population in the Netherlands is genetically diverse, with most isolates carrying species-specific AmpC-type β-lactamases. Isolates with low MIC for meropenem that lack porins and major carbapenemases represent a low-risk for public health.

U2 - 10.1186/s12866-026-04741-1

DO - 10.1186/s12866-026-04741-1

M3 - Article

C2 - 41618131

SN - 1471-2180

VL - 26

JO - BMC Microbiology

JF - BMC Microbiology

IS - 1

M1 - 192

ER -

Ambler class C-type β-lactamases and porin alterations in Enterobacter cloacae complex and Klebsiella aerogenes in the Netherlands, 2012-2023

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Correction: Ambler class C-type β-lactamases and porin alterations in Enterobacter cloacae complex and Klebsiella aerogenes in the Netherlands, 2012–2023 (BMC Microbiology, (2026), 26, 1, (192), 10.1186/s12866-026-04741-1)

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