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Peer-reviewedCC BY-NC 4.0Iranian Journal of Microbiology

Ceftazidime-avibactam activity against urinary carbapenem resistance Escherichia coli and Klebsiella pneumoniae isolates

  • Siavosh Salmanzadeh-Ahrabi1
  • Farzaneh Salehinejad2
  • Masoud Sokhanvar-Mahani3
  1. 1Women Research Center, Alzahra University, Tehran, Iran
  2. 2Department of Biotechnology, Faculty of Basic Sciences, Science and Research Branch, Islamic Azad University, Tehran, Iran
  3. 3Department of Microbiology and Microbial Biotechnology, Faculty of Life Sciences and Biotechnology, Shahid Beheshti University, Tehran, Iran
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Abstract

Background and Objectives:: Urinary tract infections (UTIs) are among the most prevalent bacterial infections in women, with Escherichia coli and Klebsiella pneumoniae as leading causative pathogens. The emergence of multidrug-resistant (MDR) and carbapenem-resistant strains poses a significant therapeutic challenge. Ceftazidime–avibactam (CZA) has shown activity against β-lactamase-producing Gram-negative bacteria; however, data on its activity against urinary carbapenem-resistant isolates remain limited. This study aimed to determine CZA activity against urinary carbapenem-resistant E. coli and K. pneumoniae isolates.

Materials and Methods:: In this cross-sectional study, antimicrobial susceptibility testing was performed using the disk diffusion method according to CLSI guidelines. The tested antibiotics included carbapenems, third-generation cephalosporins, aminoglycosides, levofloxacin, fosfomycin, and CZA. Extended-spectrum β-lactamase (ESBL) production was assessed using the combined-disk method.

Results:: A total of 76 previously collected urinary bacterial isolates, including 44 (57.9%) E. coli and 32 (42.1%) K. pneumoniae isolates were included in this study. Carbapenem resistance was detected in 25.0% (11/44) of E. coli and 28.1% (9/32) of K. pneumoniae isolates. ESBL production was observed in 36.4% and 37.5%, respectively. Overall, CZA susceptibility was 68.2% for E. coli and 68.7% for K. pneumoniae, decreasing to 27.3% and 22.2%, respectively, among carbapenem-resistant isolates. Overall, 25.0% of carbapenem-resistant isolates remained susceptible to CZA. Fosfomycin susceptibility was 81.8% and 46.9% among E. coli and K. pneumoniae, respectively.

Conclusion:: CZA demonstrated substantial in vitro activity against urinary E. coli and K. pneumoniae isolates; however, its activity was markedly reduced among carbapenem-resistant strains. These findings highlight the importance of susceptibility-guided use of CZA and continued surveillance of antimicrobial resistance.

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Cite

BibTeXRIS
BibTeX
@article{salmanzadehahrabi2026ceftazidimeavibactam,
  title = {{Ceftazidime-avibactam activity against urinary carbapenem resistance Escherichia coli and Klebsiella pneumoniae isolates}},
  author = {Siavosh Salmanzadeh-Ahrabi and Farzaneh Salehinejad and Masoud Sokhanvar-Mahani},
  journal = {Iranian Journal of Microbiology},
  year = {2026},
  month = nov,
  doi = {10.18502/ijm.v18i5.22855},
  url = {https://doi.org/10.18502/ijm.v18i5.22855},
  note = {CC BY-NC 4.0},
}
RIS
TY  - JOUR
TI  - Ceftazidime-avibactam activity against urinary carbapenem resistance Escherichia coli and Klebsiella pneumoniae isolates
AU  - Siavosh Salmanzadeh-Ahrabi
AU  - Farzaneh Salehinejad
AU  - Masoud Sokhanvar-Mahani
PY  - 2026
DA  - 2026/11/06
JO  - Iranian Journal of Microbiology
DO  - 10.18502/ijm.v18i5.22855
UR  - https://doi.org/10.18502/ijm.v18i5.22855
AB  - Background and Objectives:: Urinary tract infections (UTIs) are among the most prevalent bacterial infections in women, with Escherichia coli and Klebsiella pneumoniae as leading causative pathogens. The emergence of multidrug-resistant (MDR) and carbapenem-resistant strains poses a significant therapeutic challenge. Ceftazidime–avibactam (CZA) has shown activity against β-lactamase-producing Gram-negative bacteria; however, data on its activity against urinary carbapenem-resistant isolates remain limited. This study aimed to determine CZA activity against urinary carbapenem-resistant E. coli and K. pneumoniae isolates.  Materials and Methods:: In this cross-sectional study, antimicrobial susceptibility testing was performed using the disk diffusion method according to CLSI guidelines. The tested antibiotics included carbapenems, third-generation cephalosporins, aminoglycosides, levofloxacin, fosfomycin, and CZA. Extended-spectrum β-lactamase (ESBL) production was assessed using the combined-disk method.  Results:: A total of 76 previously collected urinary bacterial isolates, including 44 (57.9%) E. coli and 32 (42.1%) K. pneumoniae isolates were included in this study. Carbapenem resistance was detected in 25.0% (11/44) of E. coli and 28.1% (9/32) of K. pneumoniae isolates. ESBL production was observed in 36.4% and 37.5%, respectively. Overall, CZA susceptibility was 68.2% for E. coli and 68.7% for K. pneumoniae, decreasing to 27.3% and 22.2%, respectively, among carbapenem-resistant isolates. Overall, 25.0% of carbapenem-resistant isolates remained susceptible to CZA. Fosfomycin susceptibility was 81.8% and 46.9% among E. coli and K. pneumoniae, respectively.  Conclusion:: CZA demonstrated substantial in vitro activity against urinary E. coli and K. pneumoniae isolates; however, its activity was markedly reduced among carbapenem-resistant strains. These findings highlight the importance of susceptibility-guided use of CZA and continued surveillance of antimicrobial resistance.
SN  - 2008-3289
SN  - 2008-4447
ER  -