Citations

In this issue of the Journal of Clinical Microbiology , R. E. Bumgarner, D. Harrison, and J. E. Hsu (J Clin Microbiol 58:e00121-19, 2020, https://doi.org/10.1128/JCM.00121-19 ) address in a retrospective analysis that clonality of Cutibacterium acnes isolates from deep tissue specimens obtained from patients during revision shoulder arthroplasty cannot be assumed.

BACKGROUND: Cross-sectional studies in ulcerative colitis (UC) have shown at best a moderate association between histologic and clinical measures of disease activity, but few longitudinal studies have evaluated this relationship. As endoscopy and histology are both independent predictors of clinical outcomes in UC, there remains a need to assess these measures in parallel to demonstrate clinical benefit. HICKORY (NCT02100696) is an ongoing Phase 3 study evaluating etrolizumab in anti-tumor necrosis factor (aTNF)–experienced patients with moderate-to-severe UC. The correlation between histologic changes and established disease activity measures at end of induction (week 14) was assessed using data from the open-label induction (OLI) cohort of HICKORY. METHODS: Study analysis is based on data from patients in the OLI cohort who received ≥1 dose of etrolizumab 105 mg subcutaneously every 4 weeks during the 14-week induction phase. Baseline and week 14 biopsies were scored by 1 of 4 central readers using the Nancy histologic index (NHI) and the Robarts histopathology index (RHI) in patients who had active baseline histology (NHI >1 and RHI >3) and complete scoring at week 14 (n = 97). Binary week 14 histologic outcomes were characterized by presence or absence of neutrophils (NHI ≤1 or RHI ≤3 and Geboes subgrades 2B.0/3.0). Mayo Clinic score (MCS) endoscopic subscore (ES) was used to assess endoscopy. Pairwise associations were quantified by Spearman correlation (ρ; for correlation between change from baseline scores) and Cohen kappa coefficients (κ; for agreement among week 14 outcomes). ΔNHI and ΔRHI were compared to determine presence of a minimum clinically important difference (MCID) in MCS (∆MCS ≥3 from baseline). RESULTS: At week 14, 22% (21/97), 23% (22/97), and 8% (8/97) of patients achieved resolution of neutrophilic inflammation based on either NHI or RHI/Geboes, endoscopic improvement (ES ≤ 1), and endoscopic remission (ES = 0), respectively. Among patients with endoscopic improvement and endoscopic remission, neutrophilic resolution was achieved in 55% (12/22) and 75% (6/8) of patients, respectively. ΔNHI and ΔRHI were highly correlated (ρ = 0.91). There was weak to no association between ΔNHI/ΔRHI/ΔES and Δfecal calprotectin (ρ = –0.02 to 0.38), ΔC-reactive protein (ρ = 0.03 to 0.07), Δalbumin (ρ = –0.19 to –0.10), Δhemoglobin (ρ = –0.22 to –0.19), and Δsegmented neutrophils in the blood (ρ = –0.06 to 0.01). Weak correlations were observed between ΔNHI/ΔRHI and ΔES (ρ = 0.26–0.27), Δrectal bleeding (ρ = 0.24–0.28), and Δstool frequency (ρ = 0.40–0.42). Correlations between NHI, RHI/Geboes, and ES with symptomatic outcomes were weak (κ = 0.28–0.45). Difference in the mean grouped by achievement of ΔMCS ≥3 suggests MCIDs in ΔNHI and ΔRHI of 1.2 and 8.6, respectively. CONCLUSION(S): The analysis showed weak to moderate agreement between changes in histologic scores and changes in endoscopic scores, and weak to no agreement between changes in histologic scores and changes in laboratory results at week 14. There was a weak correlation between histologic scores and symptoms at the end of induction. MCID results suggest that both the NHI and RHI appear to effectively evaluate neutrophilic resolution, making the changes in score more clinically interpretable.

Despite the increasing reliance on polymyxin antibiotics (polymyxin B and colistin) for treatment of multidrug-resistant Gram-negative infections, many clinical laboratories are unable to perform susceptibility testing due to the lack of accurate and reliable methods. Although gradient agar diffusion is commonly performed for other antimicrobials, its use for polymyxins is discouraged due to poor performance characteristics.

Abstract Background Polymerase chain reaction (PCR)/sequencing targeting the 16S ribosomal RNA (rRNA) gene to detect bacteria in normally sterile tissues and fluids has become increasingly popular in clinical medicine. This culture-independent technique can detect bacteria that are nonviable or difficult to cultivate using conventional methods. The clinical value of this type of testing is not well defined. We aimed to assess the diagnostic value of 16S rRNA PCR/Sanger sequencing as a clinical diagnostic assay at Mayo Clinic. Methods This is an interim analysis of the first 173 of 478 patients who had 16S rRNA PCR/Sanger sequencing done on sterile tissues or fluids at our institution from April, 2017 to November, 2018 as part of routine clinical practice. Medical records are being retrospectively reviewed, with results compared with those of culture. Results We reviewed 207 specimens from 173 patients (musculoskeletal 79%, cardiovascular 7%, central nervous system 4%, other 9%) that underwent 16S rRNA PCR/Sanger sequencing by clinical request (Table 1). In 90% of these specimens, the test was pre-planned rather than added-on. Nine specimens were excluded from analysis, as cultures were not performed. Overall concordance of culture with PCR/sequencing was 81% (160/197; P < 0.0001). Of 44 culture-positive specimens, PCR detected the same bacterium in 21 (48%) (Table 2). 45% (20/44) of those with positive cultures and 46% of those with positive PCR/sequencing results had received prior antimicrobial therapy (Table 3). PCR was negative in 139/144 specimens that were culture-negative (97%). PCR/sequencing was helpful in detecting a putative bacterial pathogen in 4 patients with negative cultures (Table 4). Conclusion Overall, 16S rRNA PCR/Sanger sequencing improved diagnostic yield compared with culture in a minority of cases. The described assay is limited by its inability to detect polymicrobial infections, a technical limitation that could possibly be addressed using massive parallel sequencing. Careful selection of cases and a save and add-on approach may be more cost-effective than upfront testing, although this was requested in a minority of cases. Disclosures Robin Patel, MD, ASM and IDSA: Other Financial or Material Support, Travel reimbursement, editor’s stipends; CD Diagnostics, Merck, Hutchison Biofilm Medical Solutions, Accelerate Diagnostics, ContraFect, TenNor Therapeutics Limited, Shionogi: Grant/Research Support; Curetis, Specific Technologies, NextGen Diagnostics, PathoQuest, Qvella: Consultant; NBME, Up-to-Date, the Infectious Diseases Board Review Course: Honorarium recipient, Other Financial or Material Support; Patent on Bordetella pertussis/parapertussis PCR issued, a patent on a device/method for sonication with royalties paid by Samsung to Mayo Clinic, and a patent on an anti-biofilm substance issued: Other Financial or Material Support, Patents.