{"doi":"10.1093/cid/ciab450","title":"Azithromycin and Ciprofloxacin Treatment Outcomes During an Outbreak of Multidrug-Resistant <i>Shigella sonnei</i> Infections in a Retirement Community—Vermont, 2018","abstract":"BACKGROUND: In 2018, the Centers for Disease Control and Prevention and the Vermont Department of Health investigated an outbreak of multidrug-resistant Shigella sonnei infections in a retirement community that offered a continuum of care from independent living through skilled nursing care. The investigation identified 24 culture-confirmed cases. Isolates were resistant to trimethoprim-sulfamethoxazole, ampicillin, and ceftriaxone, and had decreased susceptibility to azithromycin and ciprofloxacin. METHODS: To evaluate clinical and microbiologic response, we reviewed inpatient and outpatient medical records for treatment outcomes among the 24 patients with culture-confirmed S. sonnei infection. We defined clinical failure as diarrhea (≥3 loose stools per day) for ≥1 day after treatment finished, and microbiologic failure as a stool culture that yielded S. sonnei after treatment finished. We used broth microdilution to perform antimicrobial susceptibility testing, and whole genome sequencing to identify resistance mechanisms. RESULTS: Isolates contained macrolide resistance genes mph(A) and erm(B) and had azithromycin minimum inhibitory concentrations above the Clinical and Laboratory Standards Institute epidemiological cutoff value of ≤16 µg/mL. Among 24 patients with culture-confirmed Shigella infection, 4 were treated with azithromycin; all had clinical treatment failure and 2 also had microbiologic treatment failure. Isolates were susceptible to ciprofloxacin but contained a gyrA mutation; 2 patients failed treatment with ciprofloxacin. CONCLUSIONS: These azithromycin treatment failures demonstrate the importance of clinical breakpoints to aid clinicians in identifying alternative treatment options for resistant strains. Additionally, these treatment failures highlight a need for comprehensive susceptibility testing and systematic outcome studies, particularly given the emergence of multidrug-resistant Shigella among an expanding range of patient populations.","journal":"Clinical Infectious Diseases","year":2021,"id":182683,"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":14,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9454,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2021-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":733795,"name":"Cindy R. Friedman","orcid":"0000-0003-1583-4617","position":1,"is_corresponding":false},{"id":735696,"name":"Veronica Fialkowski","orcid":null,"position":2,"is_corresponding":false},{"id":735145,"name":"Jennifer P Collins","orcid":"0000-0003-1549-2485","position":3,"is_corresponding":false},{"id":727055,"name":"Jonathan Strysko","orcid":"0000-0002-5258-7654","position":4,"is_corresponding":false},{"id":656230,"name":"Zachary Marsh","orcid":null,"position":5,"is_corresponding":false},{"id":735697,"name":"Jessica C. Chen","orcid":null,"position":6,"is_corresponding":false},{"id":735698,"name":"Elizabeth H Meservey","orcid":null,"position":7,"is_corresponding":false},{"id":735699,"name":"Azizat A Adediran","orcid":null,"position":8,"is_corresponding":false},{"id":735146,"name":"Morgan N. Schroeder","orcid":"0009-0004-6049-7888","position":9,"is_corresponding":false},{"id":735147,"name":"Ashutosh Wadhwa","orcid":"0000-0001-7579-1757","position":10,"is_corresponding":false},{"id":458187,"name":"Kathleen E. Fullerton","orcid":null,"position":11,"is_corresponding":false},{"id":695409,"name":"Louise Francois Watkins","orcid":"0000-0002-1165-1162","position":12,"is_corresponding":false},{"id":256340,"name":"Radhika Gharpure","orcid":"0000-0002-0702-5628","position":0,"is_corresponding":true}],"reference_count":24,"raw_metadata":null,"created_at":"2026-07-18T23:48:13.605421Z","pmid":"33993224","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":[]}