Forbes, Betty A.

In 2011, we initiated a sentinel surveillance network to assess changes in Clostridioides (formerly Clostridium ) difficile antimicrobial susceptibility to fidaxomicin from 6 geographically dispersed medical centers in the United States. This report summarizes data from 2013 to 2016. C. difficile isolates or toxin-positive stools from patients were referred to a central laboratory. Antimicrobial susceptibility was determined by agar dilution. CLSI, EUCAST, or FDA breakpoints were used, where applicable.

Abstract Background Trends in the distribution of ribotypes for C. difficile associated diarrheal isolates obtained over time in the United States are lacking. As part of surveillance program for C. difficile susceptibility, we analyzed stool isolates for ribotype distribution from a phase 2 trial of surotomycin (2010–2011) (North America sites) as well as a national surveillance study from 2011–2014. Isolates for the surveillance study were referred from 6 geographically distinct medical centers. Methods C. difficile isolates or C. difficile toxin + stools from patients with C. difficile associated diarrhea (CDAD) were submitted for testing to Tufts Medical Center. Following isolation and confirmation as C. difficile, a random sample of isolates were ribotyped by PCR capillary gel electrophoresis. Results 673 isolates over the 5 years of the analysis have been ribotyped to date. There were 49 unique ribotype designations, and 16 ribotypes had more than 10 isolates. The ribotype distribution by year is shown in the table. Conclusion There has been a change in the frequency of ribotypes over time in the US. Of the most common ribotypes seen, 027 has decreased by over 50% while there has been an increase of 014-020, 002, and 106. 014-020 is now the most common ribotype seen in the US. These data suggest that there is a changing epidemiology of C. difficile in the US and continuous monitoring of the ribotype distributions and clinical implications is warranted. Disclosures D. R. Snydman, Merck: Consultant and Grant Investigator, Consulting fee and Research grant; Shire: Consultant, Consulting fee; Summit PLC: Consultant and Grant Investigator, Consulting fee and Research grant; BioK+: Consultant, Consulting fee; Actelion: Grant Investigator, Research grant; S. G. Jenkins, Cormedix: Consultant, Consulting fee; Bayer: Consultant, Consulting fee; Merck: Grant Investigator and Scientific Advisor, Research grant; E. J. C. Goldstein, Merck: Grant Investigator, Scientific Advisor and Speaker’s Bureau, Consulting fee and Grant recipient; Cubist: Grant Investigator, Scientific Advisor and Speaker’s Bureau, Consulting fee; Actelion: Grant Investigator, Grant recipient; Summit PLC: Grant Investigator and Scientific Advisor, Grant recipient; R. Patel, Curetis: Consultant, Grant Investigator and Speaker’s Bureau, Consulting fee and Research grant; Pocared: Grant Investigator, Research grant; nanoMR: Grant Investigator, Research grant; BioFire: Grant Investigator, Research grant; Check-Points: Grant Investigator, Research grant; 3M: Grant Investigator, Research grant; Cubist: Grant Investigator, Research grant; Merck: Grant Investigator, Research grant; S. Johnson, Bio-K+: Consultant, Consulting fee; D. N. Gerding, Merck, Shire, Cubist, Rebiotix, sanofi pasteur, Summit, DaVoltera, Actelion: Consultant, Consulting fee; CDC, US Dept of Veterans Affairs Research Service: Grant Investigator, Research grant

ABSTRACT In 2011 a surveillance study for the susceptibility to fidaxomicin and epidemiology of Clostridium difficile isolates in the United States was undertaken in seven geographically dispersed medical centers. This report encompasses baseline surveillance in 2011 and 2012 on 925 isolates. A convenience sample of C. difficile isolates or toxin positive stools from patients were referred to a central laboratory. Antimicrobial susceptibility was determined by agar dilution (CLSI M11-A8). Clinical and Laboratory Standards Institute (CLSI), Food and Drug Administration, or European Union of Clinical Antimicrobial Susceptibility Testing (EUCAST) breakpoints were applied where applicable. Toxin gene profiles were characterized by multiplex PCR on each isolate. A random sample of 322 strains, stratified by institution, underwent restriction endonuclease analysis (REA). The fidaxomicin MIC 90 was 0.5 μg/ml for all isolates regardless of REA type or toxin gene profile, and all isolates were inhibited at ≤1.0 μg/ml. By REA typing, BI strains represented 25.5% of the isolates. The toxin gene profile of tcdA , tcdB , and cdtA/B positive with a tcdC 18-bp deletion correlated with BI REA group. Moxifloxacin and clindamycin resistance was increased among either BI or binary toxin-positive isolates. Metronidazole and vancomycin showed reduced susceptibility (EUCAST criteria) in these isolates. Geographic variations in susceptibility, REA group and binary toxin gene presence were observed. Fidaxomicin activity against C. difficile isolated in a national surveillance study did not change more than 1 year after licensure. This analysis provides baseline results for future comparisons.

Abstract The critical role of the microbiology laboratory in infectious disease diagnosis calls for a close, positive working relationship between the physician and the microbiologists who provide enormous value to the health care team. This document, developed by both laboratory and clinical experts, provides information on which tests are valuable and in which contexts, and on tests that add little or no value for diagnostic decisions. Sections are divided into anatomic systems, including Bloodstream Infections and Infections of the Cardiovascular System, Central Nervous System Infections, Ocular Infections, Soft Tissue Infections of the Head and Neck, Upper Respiratory Infections, Lower Respiratory Tract infections, Infections of the Gastrointestinal Tract, Intraabdominal Infections, Bone and Joint Infections, Urinary Tract Infections, Genital Infections, and Skin and Soft Tissue Infections; or into etiologic agent groups, including Tickborne Infections, Viral Syndromes, and Blood and Tissue Parasite Infections. Each section contains introductory concepts, a summary of key points, and detailed tables that list suspected agents; the most reliable tests to order; the samples (and volumes) to collect in order of preference; specimen transport devices, procedures, times, and temperatures; and detailed notes on specific issues regarding the test methods, such as when tests are likely to require a specialized laboratory or have prolonged turnaround times. There is redundancy among the tables and sections, as many agents and assay choices overlap. The document is intended to serve as a reference to guide physicians in choosing tests that will aid them to diagnose infectious diseases in their patients.

Abstract The critical role of the microbiology laboratory in infectious disease diagnosis calls for a close, positive working relationship between the physician and the microbiologists who provide enormous value to the health care team. This document, developed by both laboratory and clinical experts, provides information on which tests are valuable and in which contexts, and on tests that add little or no value for diagnostic decisions. Sections are divided into anatomic systems, including Bloodstream Infections and Infections of the Cardiovascular System, Central Nervous System Infections, Ocular Infections, Soft Tissue Infections of the Head and Neck, Upper Respiratory Infections, Lower Respiratory Tract infections, Infections of the Gastrointestinal Tract, Intraabdominal Infections, Bone and Joint Infections, Urinary Tract Infections, Genital Infections, and Skin and Soft Tissue Infections; or into etiologic agent groups, including Tickborne Infections, Viral Syndromes, and Blood and Tissue Parasite Infections. Each section contains introductory concepts, a summary of key points, and detailed tables that list suspected agents; the most reliable tests to order; the samples (and volumes) to collect in order of preference; specimen transport devices, procedures, times, and temperatures; and detailed notes on specific issues regarding the test methods, such as when tests are likely to require a specialized laboratory or have prolonged turnaround times. There is redundancy among the tables and sections, as many agents and assay choices overlap. The document is intended to serve as a reference to guide physicians in choosing tests that will aid them to diagnose infectious diseases in their patients.