Genomic reconstruction and directed interventions in a multidrug-resistant Shigellosis outbreak in Seattle, WA, USA: a genomic surveillance study.

BACKGROUND: Shigella spp have been associated with community-wide outbreaks in urban settings. We analysed a sustained shigellosis outbreak in Seattle, WA, USA, to understand its origins and mechanisms of antimicrobial resistance, define ongoing transmission patterns, and optimise strategies for treatment and infection control. METHODS: We did a retrospective study of all Shigella isolates identified from stool samples at the clinical laboratories at Harborview Medical Center and University of Washington Medical Center (Seattle, WA, USA) from May 1, 2017, to Feb 28, 2022. We characterised isolates by species identification, phenotypic susceptibility testing, and whole-genome sequencing. Demographic characteristics and clinical outcomes of the patients were retrospectively examined. FINDINGS: 171 cases of shigellosis were included. 78 (46%) patients were men who have sex with men (MSM), and 88 (52%) were people experiencing homelessness (PEH). Although 84 (51%) isolates were multidrug resistant, 100 (70%) of 143 patients with data on antimicrobial therapy received appropriate empirical therapy. Phylogenomic analysis identified sequential outbreaks of multiple distinct lineages of Shigella flexneri and Shigella sonnei. Discrete clonal lineages (ten in S flexneri and nine in S sonnei) and resistance traits were responsible for infection in different at-risk populations (ie, MSM, PEH), enabling development of effective guidelines for empirical treatment. The most prevalent lineage in Seattle was probably introduced to Washington State via international travel, with subsequent domestic transmission between at-risk groups. INTERPRETATION: An outbreak in Seattle was driven by parallel emergence of multidrug-resistant strains involving international transmission networks and domestic transmission between at-risk populations. Genomic analysis elucidated not only outbreak origin, but directed optimal approaches to testing, treatment, and public health response. Rapid diagnostics combined with detailed knowledge of local epidemiology can enable high rates of appropriate empirical therapy even in multidrug-resistant infection. FUNDING: None.

Mixed-methods development of a new patient-reported outcome instrument for chronic low back pain: part 1-the Patient Assessment for Low Back Pain - Symptoms (PAL-S).

We describe the mixed-methods (qualitative and quantitative) development and preliminary validation of the Patient Assessment for Low Back Pain-Symptoms (PAL-S), a patient-reported outcome measure for use in chronic low back pain (cLBP) clinical trials. Qualitative methods (concept elicitation and cognitive interviews) were used to identify and refine symptom concepts and quantitative methods (classical test theory and Rasch measurement theory) were used to evaluate item- and scale-level performance of the measure using an iterative approach. Patients with cLBP participated in concept elicitation interviews (N = 43), cognitive interviews (N = 38), and interview-based assessment of paper-to-electronic mode equivalence (N = 8). A web-based sample of patients with self-reported cLBP participated in quantitative studies to evaluate preliminary (N = 598) and revised (n = 401) drafts and a physician-diagnosed cohort of patients with cLBP (N = 45) participated in preliminary validation of the measure. The PAL-S contained 14 items describing symptoms (overall pain, sharp, prickling, sensitive, tender, radiating, shocking, shooting, burning, squeezing, muscle spasms, throbbing, aching, and stiffness). Item-level performance, scale structure, and scoring seemed to be appropriate. One-week test-retest reproducibility was acceptable (intraclass correlation coefficient 0.81 [95% confidence interval, 0.61-0.91]). Convergent validity was demonstrated with total score and MOS-36 Bodily Pain (Pearson correlation -0.79), Neuropathic Pain Symptom Inventory (0.73), Roland-Morris Disability Questionnaire (0.67), and MOS-36 Physical Functioning (-0.65). Individual item scores and total score discriminated between numeric rating scale tertile groups and painDETECT categories. Respondent interpretation of paper and electronic administration modes was equivalent. The PAL-S has demonstrated content validity and is potentially useful to assess treatment benefit in cLBP clinical trials.

Assessment of Patient-Reported Outcome Instruments to Assess Chronic Low Back Pain.

Objective: To identify patient-reported outcome (PRO) instruments that assess chronic low back pain (cLBP) symptoms (specifically pain qualities) and/or impacts for potential use in cLBP clinical trials to demonstrate treatment benefit and support labeling claims. Design: Literature review of existing PRO measures. Methods: Publications detailing existing PRO measures for cLBP were identified, reviewed, and summarized. As recommended by the US Food & Drug Administration (FDA) PRO development guidance, standard measurement characteristics were reviewed, including development history, psychometric properties (validity and reliability), ability to detect change, and interpretation of observed changes. Results: Thirteen instruments were selected and reviewed: Low Back Pain Bothersomeness Scale, Neuropathic Pain Symptom Inventory, PainDETECT, Pain Quality Assessment Scale Revised, Revised Short Form McGill Pain Questionnaire, Low Back Pain Impact Questionnaire, Oswestry Disability Index, Pain Disability Index, Roland-Morris Disability Questionnaire, Brief Pain Inventory and Brief Pain Inventory Short Form, Musculoskeletal Outcomes Data Evaluation and Management System Spine Module, Orebro Musculoskeletal Pain Questionnaire, and the West Haven-Yale Multidimensional Pain Inventory Interference Scale. The instruments varied in the aspects of pain and/or impacts that they assessed, and none of the instruments fulfilled all criteria for use in clinical trials to support labeling claims based on recommendations outlined in the FDA PRO guidance. Conclusions: There is an unmet need for a validated PRO instrument to evaluate cLBP-related symptoms and impacts for use in clinical trials.