{"doi":"10.1128/aac.01258-24","title":"Molecular epidemiology of β-lactamases in ceftriaxone-resistant Enterobacterales bloodstream infections in the mid-Atlantic United States","abstract":"ABSTRACT Ceftriaxone-resistant Enterobacterales remain a public health threat; contemporary data investigating their molecular epidemiology are limited. Five hundred consecutive ceftriaxone-resistant (MIC ≥ 4 µg/mL) Enterobacterales bloodstream isolates were collected between 2018 and 2022 from three Maryland hospitals. Broth microdilution confirmed antibiotic susceptibilities. Whole-genome sequencing identified extended-spectrum β-lactamase (ESBL) and ampC genes both in bacterial chromosomes (c- ampC ) and on plasmids (p- ampC ). Mutations in promoter or attenuator regions of the Escherichia coli c- ampC gene (i.e., bla EC gene) with the potential to result in ampC derepression were investigated. The presence of ESBL or ampC genes was confirmed in 497 (99.4%) isolates. Two hundred seventy-nine (55.8%) isolates had both ESBL and ampC genes. ESBL families were identified among 398 (80%) patients: bla CTX-M ( n = 370), bla SHV ( n = 17), bla OXY ( n = 14), and bla VEB ( n = 5). Ceftriaxone-resistant Enterobacterales species carrying ESBL genes included the following: E. coli (67%), Klebsiella pneumoniae (24%), Klebsiella oxytoca (4%), Proteus mirabilis (2%), Enterobacter cloacae complex (2%), Klebsiella aerogenes (1%), Providencia stuartii (<1%), and Serratia marcescens (<1%). c- ampC genes were identified in 374 (75%) of the 500 isolates. Only 7% of E. coli isolates with mutations in the promoter or attenuator region of the c- ampC gene exhibited resistance to cefoxitin, a proxy for increased AmpC production. Two p- ampC genes were confirmed in 25 (5%) of the 500 isolates: bla CMY-59 (72%) and bla DHA-1 (28%; confined to E. coli [92%] and K. pneumoniae [8%]). Until comprehensive β-lactamase molecular testing is available, the species-specific prevalence of ESBL and ampC genes in ceftriaxone-resistant Enterobacterales should be considered to promote effective albeit judicious antibiotic prescribing. Mutations in promoter or attenuator regions of the E. coli c- ampC gene do not appear to contribute significantly to increased AmpC production in this species.","journal":"Antimicrobial Agents and Chemotherapy","year":2025,"id":516387,"datarank":0.3453877639491069,"base_score":2.302585092994046,"endowment":2.302585092994046,"self_citation_contribution":0.3453877639491069,"citation_network_contribution":0.0,"self_endowment_contribution":0.3453877639491069,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":9,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9275,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2025-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":573746,"name":"Yehudit Bergman","orcid":"0000-0002-4262-7173","position":1,"is_corresponding":false},{"id":680802,"name":"Emily Jacobs","orcid":null,"position":2,"is_corresponding":false},{"id":79031,"name":"Jennifer Lu","orcid":"0000-0001-9167-2002","position":3,"is_corresponding":false},{"id":1381715,"name":"Nancy D. Hanson","orcid":"0000-0002-6558-2465","position":4,"is_corresponding":false},{"id":1025270,"name":"Rick Conzemius","orcid":"0000-0002-7116-8180","position":5,"is_corresponding":false},{"id":246183,"name":"Sara E. Cosgrove","orcid":"0000-0001-9458-4331","position":6,"is_corresponding":false},{"id":381268,"name":"Anthony Harris","orcid":"0000-0001-6270-0481","position":7,"is_corresponding":false},{"id":305631,"name":"Patricia J. Simner","orcid":"0000-0001-6134-151X","position":8,"is_corresponding":false},{"id":287739,"name":"Pranita D. Tamma","orcid":"0000-0002-4143-6324","position":9,"is_corresponding":false},{"id":792940,"name":"Dariusz A Hareza","orcid":"0000-0002-5425-7958","position":0,"is_corresponding":true}],"reference_count":33,"raw_metadata":{"citation_network_status":"fetched"},"created_at":"2026-07-19T02:48:49.486328Z","pmid":"39868794","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":[]}