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Background: Geographic and temporal trends in the distribution of PCR ribotypes for Clostridioides difficile associated diarrheal isolates obtained in the United States (US) are changing. As part of a US national surveillance program of C. difficile susceptibility to fidaxomicin, we quantified the distribution of PCR ribotypes of stool isolates collected from 2011 to 2016., Methods: C. difficile isolates or C. difficile toxin + stools from patients with C. difficile infection (CDI) were submitted for testing to Tufts Medical Center from 6 geographically distinct medical centers. Following isolation and confirmation as C. difficile, approximately 35% of the isolates were randomly sampled, stratified by center, for PCR ribotyping by capillary gel electrophoresis. Toxin gene profiling was performed on all isolates., Results: 939 isolates from a total of 2814 (33.4%) isolated over the 6 years were analyzed. Seventy unique ribotypes were observed, including 19 ribotypes observed 10 or more times. Sixteen ribotypes were not previously observed in our data base. Ribotype 027 declined by more than 60% over the 6 years of the survey from 35.3% to 13.1% (p < 0.001). Ribotype 106 was the most common in 2016, followed by 027 and 014-020. There were strong correlations between 027 and binary toxin with the 18 base pair deletion of tcdC and ribotype 078-126 had 100% concordance with the previously described tcdC 39 base pair deletion., Conclusions: The frequency of ribotypes in the US has changed with a marked decline in 027. Each of the geographical areas had variations which differed from each other, but collectively, these results suggest that the changing epidemiology of C. difficile in the US is consistent with what is being seen in Europe. Continued surveillance and monitoring of changes in ribotype distributions of C. difficile are warranted., Competing Interests: Declaration of competing interest Dr. Dale N Gerding is a member of the Advisory Board for Merck. Dr. Ellie Goldstein has been on advisory boards for Merck, Summit Therapeutics, LLC. He has been on a speaker bureau for Merck. Dr. Stephen G. Jenkins has no conflicts of interest as they relate to this project. Dr. Stuart Johnson has no conflicts of interest related to this project. Ms. Laura McDermott has no conflicts of interest as they relate to this project. Dr. Robin Patel reports grants from CD Diagnostics, Merck, Hutchison Biofilm Medical Solutions, Accelerate Diagnostics, ContraFect, TenNor Therapeutics Limited and Shionogi. Dr. Patel is a consultant to Curetis, Specific Technologies, NextGen Diagnostics, PathoQuest, Selux Diagnostics and Qvella; monies are paid to Mayo Clinic. In addition, Dr. Patel has a 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. Dr. Patel receives travel reimbursement from ASM and IDSA, an editor's stipend from IDSA, and honoraria from the NBME, Up-to-Date and the Infectious Diseases Board Review Course. Dr. David R. Snydman has current research funds from Merck, Pfizer and Summit Therapeutics, LLC. Dr. Snydman has been an advisor to Merck, and Summit Therapeutics, LLC. Dr. Cheleste M. Thorpe has received research funds from Merck (formerly Cubist/Optimer), Actelion, and Summit Therapeutics, LLC. She has also been on a Summit Advisory Board and received a travel grant from Summit Therapeutics, LLC. Dr. Seth T. Walk has no conflicts of interest to report., (Copyright © 2020 The Authors. Published by Elsevier Ltd.. All rights reserved.)

The susceptibility trends for Bacteroides fragilis and related species against various antibiotics were determined using data from 3 years of surveillance (2010-2012) on 779 isolates referred by 7 medical centers. The antibiotic test panel included imipenem, ertapenem, meropenem, ampicillin-sulbactam, piperacillin-tazobactam, cefoxitin, clindamycin, moxifloxacin, tigecycline, linezolid, chloramphenicol and . MICs were determined using the agar dilution CLSI reference method. Carbapenem resistance remained low (range 1.1%-2.5%) and unchanged from 2008 to 9 through 2010-2012. Resistance also remained low to the beta-lactam/beta-lactamase inhibitor combinations (1.1%-4.4%). While resistance to clindamycin and moxifloxacin remained high; rates were lower for B. fragilis in 2010-12 (24% and 19% respectively) compared to the earlier time frame of 2008-9 (29% and 35% respectively for the earlier time frame). There were notable species and resistance associations which have been demonstrated previously. No resistance to metronidazole or chloramphenicol resistance was seen. These data demonstrate the continued variability in resistance among Bacteroides and Parabacteroides species, but do demonstrate that carbapenems and beta-lactam/beta-lactamase inhibitor combinations remain very active throughout the United States., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

The results of a multicenter US survey using the National Committee for Clinical Laboratory Standards currently recommended methodology for measuring in vitro susceptibility of 2673 isolates of Bacteroides fragilis group species were compared from 1997 to 2000. The test panel consisted of 14 antibiotics: 3 carbapenems, 3 beta-lactam-beta-lactamase inhibitors, 3 cephamycins, 2 fluoroquinolones, clindamycin, chloramphenicol, and metronidazole. Declines in the geometric mean minimum inhibitory concentrations were seen with imipenem, meropenem, ampicillin-sulbactam, and the cephamycins. Increased geometric means were observed with the fluoroquinolones and were usually accompanied by an increase in resistance rates. Bacteroides distasonis shows the highest resistance rates among beta-lactam antibiotics, whereas Bacteroides vulgatus shows the highest resistance levels among fluoroquinolones. B. fragilis shows the lowest resistance rates for all antibiotics. All strains were susceptible to chloramphenicol and metronidazole concentrations <8 microgram/mL. The data underscore the need for species identification and continued surveillance to monitor resistance patterns.

In vitro surveys of antimicrobial resistance among clinically important anaerobes are an important source of information that can be used for clinical decisions in the choice of empiric antimicrobial therapy. This study surveyed the susceptibilities of 556 clinical anaerobic isolates from four large medical centers using a broth microdilution method. Piperacillin-tazobactam was the only antimicrobial agent to which all the isolates were susceptible. Similarly, imipenem, meropenem, and metronidazole were highly active (resistance, <0.5%), whereas the lowest susceptibility rates were noted for penicillin G, ciprofloxacin, and clindamycin. For most antibiotics, blood isolates were less susceptible than isolates from intra-abdominal, obstetric-gynecologic, and other sources. All isolates of the Bacteroides fragilis group were susceptible to piperacillin-tazobactam and metronidazole, while resistance to imipenem and meropenem was low (<2%). For these same isolates, resistance rates (intermediate and resistant MICs) to ampicillin-sulbactam, cefoxitin, trovafloxacin, and clindamycin were 11, 8, 7, and 29%, respectively. Among the individual species of the B. fragilis group, the highest resistance rates were noted among the following organism-drug combinations: for clindamycin, Bacteroides distasonis and Bacteroides ovatus; for cefoxitin, Bacteroides thetaiotaomicron, B. distasonis, and Bacteroides uniformis; for ampicillin-sulbactam, B. distasonis, B. ovatus, and B. uniformis; and for trovafloxacin, Bacteroides vulgatus. For the carbapenens, imipenem resistance was noted among B. fragilis and meropenem resistance was seen among B. fragilis, B. vulgatus, and B. uniformis. With few exceptions all antimicrobial agents were highly active against isolates of Prevotella, Fusobacterium, Porphyromonas, and Peptostreptococcus. These data further establish and confirm that clinically important anaerobes can vary widely in their antimicrobial susceptibilities. Fortunately most antimicrobial agents were active against the test isolates. However, concern is warranted for what appears to be a significant increases in resistance to ampicillin-sulbactam and clindamycin.

Background: A widely observed increased risk of hepatitis C virus (HCV) infection in chronic hemodialysis patients has been previously attributed to violations of "Universal Precautions" for the control of blood-borne pathogens, as well as in part, to other risk factors, such as a history of blood transfusion or injection drug use. However, specific factors responsible for transmission have not been identified and the possibility that flaws in dialysis procedures, including sterilization, could increase the risk of transmission, has not been excluded., Methods: We investigated reuse procedures for hemodialysis equipment and tested dialyzer blood port caps for detection of hepatitis C virus RNA (HCV RNA) by reverse transcription-polymerase chain reaction (RT-PCR)., Results: Following artificial contamination of the blood port caps with blood or fluids from human HCV-positive patients, and overnight soaking in 1% Renalin, HCV RNA was detected on 4 of 20 caps contaminated with blood, 1 of 10 contaminated with serum and 8 of 24 contaminated with dialyzer blood compartment residue. HCV RNA was also detected on 1 of 111 pairs of blood port caps collected post dialysis from HCV positive patients, after soaking the caps overnight in 1% Renalin., Conclusion: The results suggest that HCV RNA might be detectable on reused dialysis equipment post sterilization procedures, if residual blood or serum is not entirely or almost entirely removed prior to sterilization. This may warrant evaluation of sterilization procedures to ensure that procedures are adequate and that protocols are rigorously followed. Further studies of sterilization procedures by sensitive techniques such as RT-PCR may be indicated.

Streptococcus pneumoniae is the predominant bacterial pathogen associated with acute otitis media (AOM), causing an estimated 7 million cases annually in the United States. Bacterial resistance should be considered when selecting an antimicrobial agent for otitis media. Significant increases in drug-resistant S pneumoniae are documented worldwide, and less than 50% of S pneumoniae strains are fully susceptible to penicillin in some regions of the United States. Although amoxicillin is recommended for uncomplicated AOM, treatment guidelines should be flexible and adaptable, taking into consideration local and regional susceptibility patterns, the age of the patient, the frequency of prior infections, and the response to prior therapy. Resistant organisms are more prevalent in children younger than 2 years of age and in those who have recurrent or persistent AOM. Overdiagnosing AOM, selecting inappropriate empiric therapy, or both, leads to overuse and misuse of antibiotics and causes increased drug resistance. This article reviews persistent and recurrent AOM and discusses the pitfalls of diagnosis and the practical limitations of current treatment recommendations.

Acute sinusitis is commonly encountered in clinical practice and treated in the primary care setting. The clinician should recognize the subtle clinical presentation of acute bacterial sinusitis and initiate appropriate, aggressive treatment. Other upper respiratory tract disorders can confound the accurate diagnosis and appropriate treatment of sinusitis. Variable patterns of microbial resistance and antibiotic susceptibility and the dissociation between in vitro findings and clinical efficacy are a treatment challenge. This report is a comprehensive review of the pathophysiology and diagnosis of acute sinusitis, infectious agents, treatment methods, antibiotic resistance patterns, and costs associated with the management of sinusitis. Treatment algorithms are presented for adult and pediatric sinusitis.

Enterococci have become important nosocomial pathogens, with Enterococcus faecalis and then Enterococcus faecium predominating. Because of the emergence of glycopeptide (vancomycin and teicoplanin) resistance in enterococci, laboratories have been required to screen for resistant strains and to identify them to the species level. This has resulted in the need for accurate identification of species less commonly associated with clinical infections, such as Enterococcus casseliflavus and Enterococcus gallinarum, which are inherently resistant to the glycopeptides. Studies evaluating commonly used commercial identification systems, have found error rates for enterococcal species identification of 2-21% for E. faecalis, 5-9% for E. faecium, and 14-79% for other species. Reporting errors may have adverse effects on the management of clinical infections, as well as in the control of multidrug-resistant strain outbreaks. The purpose of this document is to present a simplified approach to the identification of Enterococcus species that uses a combination of rapid, readily available, and inexpensive tests.

Antimicrobial resistance, including plasmid-mediated resistance, among Bacteroides fragilis group species is well documented. A 5-year (1990-1994) prospective, eight-center survey of 3,177 clinical isolates of Bacteroides species was undertaken to review trends in resistance, using the breakpoints for full and intermediate susceptibility established by the National Committee for Clinical Laboratory Standards. No documented resistance to either metronidazole or chloramphenicol was found in this survey. Among B. fragilis isolates virtually no resistance was seen to imipenem, meropenem, ampicillin/sulbactam, piperacillin/tazobactam, or ticarcillin/clavulanate. Significant increases in resistance among B. fragilis isolates to cefotetan, ceftizoxime, and clindamycin (p < .01) were noted. Resistance to cefoxitin remained unchanged. Among the non-fragilis species of the B. fragilis group, there was virtually no resistance to imipenem, meropenem, chloramphenicol, or metronidazole. The three beta-lactamase inhibitors had increasing levels of resistance, although 95%-98% of strains were susceptible (p < .05). There was a significant decline in cefoxitin, cefmetazole, and clindamycin activity over time against these strains (p <.01). There was a significant (P < .001) increase in geometric mean minimum inhibitory concentration for most drugs and species tested from 1990 to 1994. Clusters in the eight institutions could not account for this rise in resistance. This survey demonstrates that rates of resistance of B. fragilis and non-fragilis species of B. fragilis group are increasing.

Infectious complications are major contributing factors to morbidity and mortality in the ICU setting. Organisms frequently encountered in the ICU include Pseudomonas aeruginosa, Staphylococcus aureus, Haemophilus influenzae (particularly in trauma victims), enterococci, Klebsiella pneumoniae, Enterobacter spp., Acinetobacter baumanii, Escherichia coli, and Stenotrophomonas (Xanthomonas) maltophilia. Antibiotics have played a major role in the treatment of infections caused by such bacterial pathogens. Organisms have responded to the antibiotic challenge, however, evolving and developing resistance to all available antimicrobial agents to a greater or lesser degree. Specific mechanisms of resistance include reductions in cell-wall membrane permeability, alterations of antimicrobial agent target sites, enzymatic inactivation of antibiotics, and development of bypass pathways around antimicrobial targets. This article describes, pathogen by pathogen, antimicrobial agents that are useful for the treatment of infection in the ICU setting and the mechanisms whereby bacteria have short-circuited our antimicrobial armamentarium.

Nontyphoidal salmonellae (NTS) are often isolated from stool specimens of individuals having evaluation of gastroenteritis. The significance of isolation of NTS in a stool specimen from previously healthy individuals with gastroenteritis is not clear. The purpose of this study was to determine which serotypes were being isolated most frequently and whether some serotypes were responsible for the majority of infections. A 6-year review yielded 433 stool isolates of NTS. Only 12 isolates were from specimens other than stool. Thirty-five different strains were isolated over the last 6-year period. The most common isolates were S javiana, 126 (29%); S newport, 85 (20%); S typhimurium, 47 (11%); S muenchen, 28 (7%); and S heidelberg, 21 (6%). These five strains were isolated in each of the 6 years of the review and were responsible for 313 (72%) isolates. The most common isolate for each year was S javiana, a strain that has not previously been reported as the predominant human isolate in invasive diseases or in outbreaks. In fact, S javiana is not even among the 10 most common NTS isolates reported to the Centers for Disease Control and Prevention nationally.