{"doi":"10.1093/jacamr/dlad113","title":"Mutations in <i>ompK36</i> differentially impact <i>in vitro</i> synergy of meropenem/vaborbactam and ceftazidime/avibactam in combination with other antibiotics against KPC-producing <i>Klebsiella pneumoniae</i>","abstract":"Abstract Objectives Ceftazidime/avibactam and meropenem/vaborbactam are preferred agents for Klebsiella pneumoniae carbapenemase (KPC)-producing K. pneumoniae (KPC-Kp) infections and are often used in combination with other agents. We aimed to characterize the synergy of combinations against KPC-Kp with varying ompK36 genotypes. Methods KPC-Kp that harboured ompK36 WT, IS5 or glycine-aspartic acid duplication (GD) genotypes were selected. MICs were determined in triplicate. Synergy was assessed by time-kill assays for ceftazidime/avibactam and meropenem/vaborbactam in combination with colistin, gentamicin, tigecycline, meropenem or fosfomycin against 1 × 108 cfu/mL KPC-Kp. Results KPC-Kp harboured ompK36 WT (n = 5), IS5 (n = 5) or GD (n = 5); 11 were KPC-2 and 4 were KPC-3. All were susceptible to ceftazidime/avibactam and meropenem/vaborbactam. In time-kill analysis, ceftazidime/avibactam and meropenem/vaborbactam 1 × MIC exhibited mean 24 h log-kills of −2.01 and −0.84, respectively. Ceftazidime/avibactam was synergistic in combination with colistin independent of ompK36 genotype. Ceftazidime/avibactam combinations impacted by porin mutations (compared to WT) were meropenem (−5.18 versus −6.62 mean log-kill, P &amp;lt; 0.001) and fosfomycin (−3.98 versus −6.58, P = 0.058). Mean log-kills with meropenem/vaborbactam were greatest in combination with gentamicin (−5.36). In the presence of porin mutations, meropenem/vaborbactam killing activity was potentiated by the addition of colistin (−6.65 versus −0.70, P = 0.03) and fosfomycin (−3.12 versus 1.54, P = 0.003). Conclusions Our results shed new light on the synergy of ceftazidime/avibactam and meropenem/vaborbactam combinations against KPC-Kp with or without porin mutations. Killing activity of ceftazidime/avibactam with other cell wall active agents was decreased against isolates with porin mutations. On the other hand, some meropenem/vaborbactam combinations demonstrated enhanced killing in the presence of porin mutations.","journal":"JAC-Antimicrobial Resistance","year":2023,"id":350300,"datarank":0.0,"base_score":0.0,"endowment":0.0,"self_citation_contribution":0.0,"citation_network_contribution":0.0,"self_endowment_contribution":0.0,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":10,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9531,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2023-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":282878,"name":"Ellen G Kline","orcid":"0009-0006-7167-6368","position":1,"is_corresponding":false},{"id":356082,"name":"M. Patrick Griffith","orcid":"0000-0003-1012-881X","position":2,"is_corresponding":false},{"id":827270,"name":"Chelsea E Jones","orcid":null,"position":3,"is_corresponding":false},{"id":1073454,"name":"Abigail M Rubio","orcid":null,"position":4,"is_corresponding":false},{"id":896219,"name":"Kevin M Squires","orcid":"0009-0007-7818-905X","position":5,"is_corresponding":false},{"id":282876,"name":"Ryan K. Shields","orcid":"0000-0001-9794-5665","position":6,"is_corresponding":false},{"id":1062129,"name":"Tara M Rogers","orcid":null,"position":0,"is_corresponding":true}],"reference_count":47,"raw_metadata":null,"created_at":"2026-07-19T01:12:23.769679Z","pmid":"37901589","pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}