{"doi":"10.1002/ctm2.801","title":"Key role of quorum‐sensing mutations in the development of <i>Staphylococcus aureus</i> clinical device‐associated infection","abstract":"In the present study, we show that the development of Staphylococcus aureus device-associated infection involves mutations in the quorum-sensing system Agr that increase biofilm formation and thereby bacterial resistance to antibiotics. The enormous difficulty clinicians face in the treatment of device-associated infections is due to the characteristic involvement of biofilms, which are bacterial agglomerations that form on the device surface and exhibit considerably increased resistance to virtually all types of antibiotics.1 One of the most frequent causes of device-associated infections is Staphylococcus aureus, which is also infamous for its exceptional recalcitrance towards antibiotic treatment.2, 3 How device-associated infections develop remains incompletely understood. This is in part since only end-point isolates from clinical device-associated infection are usually investigated. Main questions that remain include whether a device-associated infection is only caused by a selection of strains that are particularly pronounced biofilm formers or whether adaptations increasing biofilm formation occur during infection, and if so, which among them play a dominant role for that adaptation. To answer these questions, we compared sequential isolates from cases of prolonged S. aureus surgical implant infection obtained at our hospital (See Figure S1 for selection of isolates). In all cases, initial (T1) samples were taken after infection had developed post-surgery, and secondary (T2) samples were collected when recurrence or persistence of infection was diagnosed (Table S1). All bacterial samples from the T1 and T2 time points were classified as S. aureus by appearance and mass spectrometry. Remarkably, all T1 isolates were homogenously hemolytic on sheep blood agar plates, whereas all T2 samples were homogenously non-hemolytic (Figure 1A). One representative clone of each sample was stored, and all stored T1 and T2 isolates were confirmed to exhibit a hemolytic and non-hemolytic phenotype, respectively (Figure 1B). Notably, all T2 isolates also showed significantly higher in vitro biofilm-forming capacities than the corresponding T1 isolates (Figure 1C). To analyze whether genetic changes were involved in the altered phenotypes that we observed, we performed whole genome sequencing (WGS). WGS confirmed that T2 isolates were derived from the T1 isolates, as they shared several characteristics and were closely genetically related, while the isolates from different cases were genetically distant (Figure 1D, Table S1). Only the locus encoding the Agr (accessory gene regulator) quorum-sensing (QS) system4 showed non-synonymous substitutions in all six isolates (Figure 1E, Tables 1 and 2, Table S2), indicating that the consistently observed phenotypes of reduced hemolysis and increased biofilm formation in the secondary isolates were due to Agr dysfunctionality. This idea is substantiated by the fact that non-synonymous mutations in agr, but not in other genes with non-synonymous single nucleotide polymorphism (SNPs) in our isolates, explain the hemolysis and biofilm phenotypes. This is because Agr-dysfunctional mutants are known to be 1. non-hemolytic, as Agr controls the production of secreted hemolysins,4 and 2. exhibit increased biofilm formation due to the absence of the strictly Agr-controlled biofilm-structuring phenol-soluble modulin peptides and Agr-dependent regulation of biofilm matrix-degrading enzymes.5 Furthermore, the lack of hemolysis is often used in larger screens to detect Agr dysfunctionality, because it is almost always due to mutations in agr.6 The fact that all T2 samples were assessed as homogenously non-hemolytic indicates that the Agr-dysfunctional mutants that developed during device-associated infection overtook virtually the entire bacterial device-associated population. For the analysis of antibiotic resistance exhibited by the T1 and T2 isolate pairs, we chose levofloxacin (Lev), vancomycin (Van) and c","journal":"Clinical and Translational Medicine","year":2022,"id":240665,"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":44,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9526,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2022-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":868718,"name":"Feiyang Zhang","orcid":"0000-0002-3746-9756","position":1,"is_corresponding":false},{"id":517589,"name":"Ying Jian","orcid":"0000-0001-5185-2455","position":2,"is_corresponding":false},{"id":269582,"name":"Huiying Lv","orcid":null,"position":3,"is_corresponding":false},{"id":868719,"name":"Musha Hamushan","orcid":"0000-0002-7691-6408","position":4,"is_corresponding":false},{"id":268486,"name":"Junlan Liu","orcid":"0000-0002-5351-6241","position":5,"is_corresponding":false},{"id":868720,"name":"Yao Liu","orcid":"0000-0003-2499-9624","position":6,"is_corresponding":false},{"id":868721,"name":"Hua Wang","orcid":"0000-0003-2633-3420","position":7,"is_corresponding":false},{"id":868722,"name":"Jin Tang","orcid":"0000-0002-4281-0226","position":8,"is_corresponding":false},{"id":730380,"name":"Pei Han","orcid":"0000-0001-8532-9339","position":9,"is_corresponding":false},{"id":868723,"name":"Dylan J. Burgin","orcid":"0000-0002-6035-3508","position":10,"is_corresponding":false},{"id":363789,"name":"Seth W. Dickey","orcid":"0000-0003-3200-2388","position":11,"is_corresponding":false},{"id":304755,"name":"Hao Shen","orcid":"0000-0002-8698-5079","position":12,"is_corresponding":false},{"id":868724,"name":"Min Li","orcid":"0000-0002-6162-7742","position":13,"is_corresponding":false},{"id":268488,"name":"Michaël Otto","orcid":"0000-0002-2222-4115","position":14,"is_corresponding":false},{"id":268485,"name":"Lei He","orcid":"0000-0002-0215-3102","position":0,"is_corresponding":true}],"reference_count":10,"raw_metadata":null,"created_at":"2026-07-19T00:22:51.435773Z","pmid":"35389566","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":[]}