{"doi":"10.1128/aac.00898-24","title":"Prevalence of the cefazolin inoculum effect (CzIE) in nasal colonizing methicillin-susceptible <i>Staphylococcus aureus</i> in patients from intensive care units in Colombia and use of a modified rapid nitrocefin test for detection","abstract":"ABSTRACT The cefazolin inoculum effect (CzIE) has been associated with poor clinical outcomes in patients with methicillin-susceptible Staphylococcus aureus (MSSA) infections. We aimed to investigate the point prevalence of the CzIE among nasal colonizing MSSA isolates from ICU patients in a multicenter study in Colombia (2019–2023). Patients underwent nasal swabs to assess for S. aureus colonization on admission to the ICU, and some individuals had follow-up swabs. We performed cefazolin MIC by broth microdilution using standard and high inoculum and developed a modified nitrocefin-based rapid test to detect the CzIE. Whole-genome sequencing was carried out to characterize BlaZ types and allotypes, phylogenomics, and Agr-typing. A total of 352 patients were included; 46/352 (13%) patients were colonized with S. aureus and 22% (10/46) and 78% (36/46) with MRSA and MSSA, respectively. Among 36 patients who contributed with 43 MSSA colonizing isolates, 21/36 (58%) had MSSA exhibiting the CzIE. BlaZ type A and BlaZ-2 were the predominant type and allotype in 56% and 52%, respectively. MSSA belonging to CC30 were highly associated with the CzIE, and single-nucleotide polymorphism (SNP) analyses supported possible transmission of MSSA exhibiting the CzIE among some patients of the same unit. The modified nitrocefin rapid test had 100%, 94.4%, and 97.7% sensitivity, specificity, and accuracy, respectively. We found a high point prevalence of the CzIE in MSSA colonizing the nares of critically ill patients in Colombia. A modified rapid test was highly accurate in detecting the CzIE in this patient population.","journal":"Antimicrobial Agents and Chemotherapy","year":2024,"id":447572,"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":6,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9639,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2024-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":343884,"name":"Sandra Rincón","orcid":"0000-0002-8482-4554","position":1,"is_corresponding":false},{"id":1266189,"name":"Sara I Gomez Villegas","orcid":null,"position":2,"is_corresponding":false},{"id":1265652,"name":"J Manuel Matiz-González","orcid":"0000-0001-7715-8541","position":3,"is_corresponding":false},{"id":496040,"name":"Karen Ordóñez","orcid":"0000-0002-3879-3291","position":4,"is_corresponding":false},{"id":1266190,"name":"Alejandra Santamaria","orcid":null,"position":5,"is_corresponding":false},{"id":1266191,"name":"Leonardo Ospina Navarro","orcid":null,"position":6,"is_corresponding":false},{"id":1266192,"name":"Jaime Beltrán","orcid":null,"position":7,"is_corresponding":false},{"id":1265653,"name":"Freddy Guevara","orcid":"0000-0002-6256-4130","position":8,"is_corresponding":false},{"id":1265654,"name":"Yardany Rafael Méndez","orcid":"0000-0003-1528-2672","position":9,"is_corresponding":false},{"id":618252,"name":"Soraya Salcedo","orcid":"0000-0003-2110-424X","position":10,"is_corresponding":false},{"id":298633,"name":"Alexandra Porras","orcid":"0000-0002-0800-1388","position":11,"is_corresponding":false},{"id":1266193,"name":"Albert Valencia-Moreno","orcid":null,"position":12,"is_corresponding":false},{"id":1266194,"name":"Haley Greenia","orcid":null,"position":13,"is_corresponding":false},{"id":1266195,"name":"Alexander Deyanov","orcid":null,"position":14,"is_corresponding":false},{"id":356928,"name":"Rodrigo P. Baptista","orcid":"0000-0002-1806-8260","position":15,"is_corresponding":false},{"id":439780,"name":"Vincent H. Tam","orcid":"0000-0001-7071-5376","position":16,"is_corresponding":false},{"id":343885,"name":"Diana Panesso","orcid":"0000-0002-4049-9702","position":17,"is_corresponding":false},{"id":343887,"name":"Truc T. Tran","orcid":"0000-0002-2696-4196","position":18,"is_corresponding":false},{"id":582538,"name":"William R. Miller","orcid":"0000-0002-1518-2973","position":19,"is_corresponding":false},{"id":232742,"name":"César A. Arias","orcid":"0000-0001-9054-9774","position":20,"is_corresponding":false},{"id":343883,"name":"Jinnethe Reyes","orcid":"0000-0002-1722-0734","position":21,"is_corresponding":false},{"id":346151,"name":"Lina P Carvajal","orcid":null,"position":0,"is_corresponding":true}],"reference_count":45,"raw_metadata":null,"created_at":"2026-07-19T02:02:03.354708Z","pmid":"39345182","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":[]}