Antianaerobic antimicrobials: spectrum and susceptibility testing

Bacterascites caused by Salmonella spp. following a cesarean section: A case report

RATIONALE

Bacterascites are a rare complication of cesarean sections (C/S). Here, we report the case of a patient with bacterascites after an emergent C/S.

PATIENT CONCERN

A 41-year-old female reported diffuse abdominal tightness and pain for a week after C/S, who received C/S at 38 4/7 weeks due to superimposed preeclampsia and prolonged labor.

DIAGNOSES

Bacterascites caused by Salmonella species after C/S was diagnosed.

INTERVENTIONS

Initial treatment included cefmetazole and metronidazole. On day 2, paracentesis was performed, followed by albumin and hydroxyethyl starch administration. By day 3, the patient developed pulmonary edema, necessitating Lasix administration. On day 6, ascites culture revealed Salmonella species resistant to third-generation cephalosporins, leading to meropenem therapy adjustment. This resulted in improved symptoms. Meropenem was continued for 14 days to complete the treatment regimen.

OUTCOMES

Follow-up ultrasonography revealed a decrease in ascites. As the patient clinical condition improved, she was discharged on day 20 and scheduled for outpatient department follow-up. No recurrence of ascites was observed during the subsequent follow-up period of 3 months. No ascites were noted 8 days after discharge.

LESSONS

Postoperative bacterascites with Salmonella were diagnosed. Antibiotic treatment and therapeutic paracentesis were effective for this condition.

Overview of anaerobic infections in children and their treatment

Anaerobic bacteria can cause many infections in children. Because they predominant in the normal human skin and mucous membranes bacterial flora, they are often associated with bacterial infections that originate from these sites. They are difficult to isolate from infectious sites, and are frequently missed. Anaerobic infections can occur in all body sites, including the central nervous system, oral cavity, head and neck, chest, abdomen, pelvis, skin, and soft tissues. Anaerobes colonize the newborn after birth and have been isolated in several types of neonatal infections. These include cellulitis of the site of fetal monitoring, neonatal aspiration pneumonia, bacteremia, conjunctivitis, omphalitis, and infant botulism. Management of anaerobic infection is challenging because of the slow growth of these bacteria, by their polymicrobial nature and by the growing antimicrobial resistance of anaerobic. Antimicrobial therapy may be the only treatment required, and may also be an adjunct to a surgical approach. Polymicrobial aerobic-anaerobic infection generally requires delivering antimicrobial therapy effective against all pathogens. The antibiotics with the greatest activity against anaerobes include carbapenems, beta-lactam/beta-lactamase inhibitor combinations, metronidazole, and chloramphenicol. Antimicrobial resistance is growing among anaerobic bacteria. The major increased in resistance have been reported with clindamycin, cephamycins, and moxifloxacin against Bacteroides fragilis group and related strains. Resistance patterns vary between different geographic areas and medical facilities.

Anaerobic Antibiotic Coverage in Aspiration Pneumonia and the Associated Benefits and Harms: A Retrospective Cohort Study

BACKGROUND

Antibiotics with extended anaerobic coverage are used commonly to treat aspiration pneumonia, which is not recommended by current guidelines.

RESEARCH QUESTION

In patients admitted to hospital for community-acquired aspiration pneumonia, does a difference exist between antibiotic therapy with limited anaerobic coverage (LAC) vs antibiotic therapy with extended anaerobic coverage (EAC) in terms of in-hospital mortality and risk of Clostridioides difficile colitis?

STUDY DESIGN AND METHODS

We conducted a multicenter retrospective cohort study across 18 hospitals in Ontario, Canada, from January 1, 2015, to January 1, 2022. Patients were included if the physician diagnosed aspiration pneumonia and prescribed guideline-concordant first-line community-acquired pneumonia parenteral antibiotic therapy to the patient within 48 h of admission. Patients then were categorized into the LAC group if they received ceftriaxone, cefotaxime, or levofloxacin. Patients were categorized into the EAC group if they received amoxicillin-clavulanate, moxifloxacin, or any of ceftriaxone, cefotaxime, or levofloxacin in combination with clindamycin or metronidazole. The primary outcome was all-cause in-hospital mortality. Secondary outcomes included incident C difficile colitis occurring after admission. Overlap weighting of propensity scores was used to balance baseline prognostic factors.

RESULTS

The LAC and EAC groups included 2,683 and 1,316 patients, respectively. In hospital, 814 patients (30.3%) and 422 patients (32.1%) in the LAC and EAC groups died, respectively. C difficile colitis occurred in five or fewer patients (≤ 0.2%) and 11 to 15 patients (0.8%-1.1%) in the LAC and EAC groups, respectively. After overlap weighting of propensity scores, the adjusted risk difference of EAC minus LAC was 1.6% (95% CI, -1.7% to 4.9%) for in-hospital mortality and 1.0% (95% CI, 0.3%-1.7%) for C difficile colitis.

INTERPRETATION

We found that extended anaerobic coverage likely is unnecessary in aspiration pneumonia because it was associated with no additional mortality benefit, only an increased risk of C difficile colitis.

A Pediatric Case of Fusobacterium necrophorum Mastoiditis and Meningitis Case Report in a Healthy Child and Review of the Literature

In infants and children, bacterial meningitis caused by anaerobic bacteria is rare. However, a serious infection with the anaerobe Fusobacterium necrophorum can occur in previously healthy children with a peak incidence in preschool children and in adolescents. As the clinical presentation can be very similar to meningitis caused by aerobic bacteria, one should consider Fusobacterium necrophorum as the causative agent when preceded by or associated with otitis media with purulent otorrhea or mastoiditis, in combination with minimal or no improvement on empiric antibiotic treatment. As this pathogen can be difficult to culture, anaerobic cultures should be obtained. Prompt treatment with a third-generation cephalosporin and metronidazole should be initiated once suspected or confirmed. Surgical source control is often necessary, but even with adequate and prompt treatment, the morbidity and mortality in children with a Fusobacterium necrophorum meningitis remains high. In this report, we describe a case of Fusobacterium necrophorum meningitis in a previously healthy child and review the available literature.

A 36-Year-Old Male With Left-Sided Neck Pain and Progressive Dyspnea

CASE PRESENTATION

A 36-year-old male with no significant medical history presented to the ED with progressive left-sided neck and facial pain for the last 7 days. The patient also reported subjective fevers, chills, difficulty opening his mouth, and anorexia for the last 1 week. He denied cough, chest pain or tightness, shortness of breath, skin rashes, dysphagia, or odynophagia. He reported use of two to three 59.15 mL beers daily for the last 20 years. There was no recent travel or sick contact exposure. He did not report any TB exposure, IV drug use, or recent sexual encounters.

Lemierre's Syndrome Secondary to Shoulder Hematoma Complicated by COVID-19: A Case Report

This case report illustrates a unique presentation of Lemierre's syndrome precipitated by Fusobacterium necrophorum. This case report describes a 20-year-old patient who developed Lemierre's syndrome secondary to a shoulder hematoma and neck abscess with multiple systemic complications in the absence of tonsillitis or oropharyngeal infection. Two weeks prior to presentation, the patient sustained a right shoulder injury and contracted COVID-19. Due to his Lemierre's syndrome, he developed right internal jugular vein and subclavian vein thrombosis, septic lung emboli, right sided Horner's syndrome, disseminated intravascular coagulation, pelvic collection, septic arthritis of pubic symphysis and osteomyelitis of the right pubic bone, and proximal left femoral shaft. The patient received non-operative and operative management to manage his Lemierre's syndrome including surgical drainage, antibiotics, and anticoagulation; he was discharged following an extended hospital stay. This case report highlights a rare presentation of Lemierre's syndrome secondary to a shoulder hematoma in a COVID-19 positive patient, and its potential systemic and life-threatening complications. Its importance is highly relevant in the context of the COVID-19 pandemic. Further studies are warranted to explore the effect of preceding COVID-19 infections on the microbiological profile in Lemierre's syndrome.

A Rapid In Vivo Toxicity Assessment Method for Antimicrobial Peptides

Antimicrobial peptides (AMPs) represent a promising antibiotic alternative to overcome drug-resistant bacteria by inserting into the membrane of bacteria, resulting in cell lysis. However, therapeutic applications of AMPs have been hindered by their ability to lyse eukaryotic cells. GF-17 is a truncated peptide of LL-37, which has perfect amphipathicity and a higher hydrophobicity, resulting in higher haemolytic activity. However, there is no significant difference in the cytotoxicity against human lung epithelial cells between the GF-17 and LL-37 groups, indicating that there are significant differences in the sensitivity of different human cells to GF-17. In this study, LL-37 and GF-17 were administered to mouse lungs via intranasal inoculation. Blood routine examination results showed that LL-37 did not affect the red blood cells, platelet, white blood cells and neutrophil counts, but GF-17 decreased the white blood cells and neutrophil counts with the increasing concentration of peptides. GF-17-treated mice suffer a body weight loss of about 2.3 g on average in 24 h, indicating that GF-17 is highly toxic to mice. The total cell counts in the bronchoalveolar lavage fluid from GF-17-treated mice were 4.66-fold that in the untreated group, suggesting that GF-17 treatment leads to inflammation in the lungs of mice. Similarly, the histological results showed the infiltration of neutrophils in the lungs of GF-17-treated mice. The results suggest that the administration of GF-17 in the lungs of mice does not affect the red blood cells and platelet counts in the blood but promotes neutrophil infiltration in the lungs, leading to an inflammatory response. Therefore, we established a mouse acute lung injury model to preliminarily evaluate the in vivo toxicity of AMPs. For AMPs with a clinical application value, systematic research is still needed to evaluate their acute and long-term toxicity.

Cold Plasma Deposition of Tobramycin as an Approach to Localized Antibiotic Delivery to Combat Biofilm Formation

Hospital-acquired infections (HAIs) remain a significant factor in hospitals, with implant surfaces often becoming contaminated by highly resistant strains of bacteria. Recent studies have shown that electrical plasma discharges can reduce bacterial load on surfaces, and this approach may help augment traditional antibiotic treatments. To investigate this, a cold atmospheric plasma was used to deposit tobramycin sulphate onto various surfaces, and the bacterial growth rate of K. pneumoniae in its planktonic and biofilm form was observed to probe the interactions between the plasma discharge and the antibiotic and to determine if there were any synergistic effects on the growth rate. The plasma-deposited tobramycin was still active after passing through the plasma field and being deposited onto titanium or polystyrene. This led to the significant inhibition of K. pneumoniae, with predictable antibiotic dose dependence. Separate studies have shown that the plasma treatment of the biofilm had a weak antimicrobial effect and reduced the amount of biofilm by around 50%. Combining a plasma pre-treatment on exposed biofilm followed by deposited tobramycin application proved to be somewhat effective in further reducing biofilm growth. The plasma discharge pre-treatment produced a further reduction in the biofilm load beyond that expected from just the antibiotic alone. However, the effect was not additive, and the results suggest that a complex interaction between plasma and antibiotic may be at play, with increasing plasma power producing a non-linear effect. This study may contribute to the treatment of infected surgical sites, with the coating of biomaterial surfaces with antibiotics reducing overall antibiotic use through the targeted delivery of therapeutics.

Lemierre syndrome with pulmonary empyema caused by Prevotella intermedia

Lemierre syndrome is a rare disease that is most often caused by Fusobacterium necrophorum We present a case caused by Prevotella intermedia in a young, healthy man, complicated by multiple cavitary lung lesions, loculated pleural effusions requiring chest tube placement and trapezius abscess. Our case highlights (a) P. intermedia as a rare cause of Lemierre syndrome and (b) clinical response to appropriate antimicrobial therapy may be protracted.

Fifty years devoted to anaerobes: historical, lessons, and highlights

Renew interest and enthusiasm for anaerobes stem from both technological improvements (culture media, production of an adequate anaerobic atmosphere, identification methods) and greater awareness on the part of clinicians. Anaerobic infections were historically treated empirically, targeting the species known to be involved in each type of infection. Prevotella, fusobacteria, and Gram-positive cocci (GPAC) were considered responsible for infections above the diaphragm whereas for intra-abdominal infections, Bacteroides of the fragilis group (BFG), GPAC and clostridia were predominantly implicated. The antibiotic susceptibility of anaerobes was only taken into consideration by the clinician in the event of treatment failure or when faced with infections by multidrug-resistant bacteria (MDR). The evolution of antibiotic resistance together with clinical failures due to the absence of detection of hetero-resistant clones has resulted in a greater need for accessible antibiotic susceptibility testing (AST) and disc diffusion method. Improved isolation and identification of anaerobes, along with the availability of accessible and robust methods for performing AST, will ensure that treatment, whether empirical or guided by an antibiogram, will lead to better outcomes for anaerobic infections.

Antibiotic-induced collateral damage to the microbiota and associated infections

Antibiotics have transformed medicine, saving millions of lives since they were first used to treat a bacterial infection. However, antibiotics administered to target a specific pathogen can also cause collateral damage to the patient's resident microbial population. These drugs can suppress the growth of commensal species which provide protection against colonization by foreign pathogens, leading to an increased risk of subsequent infection. At the same time, a patient's microbiota can harbour potential pathogens and, hence, be a source of infection. Antibiotic-induced selection pressure can cause overgrowth of resistant pathogens pre-existing in the patient's microbiota, leading to hard-to-treat superinfections. In this Review, we explore our current understanding of how antibiotic therapy can facilitate subsequent infections due to both loss of colonization resistance and overgrowth of resistant microorganisms, and how these processes are often interlinked. We discuss both well-known and currently overlooked examples of antibiotic-associated infections at various body sites from various pathogens. Finally, we describe ongoing and new strategies to overcome the collateral damage caused by antibiotics and to limit the risk of antibiotic-associated infections.

Harnessing the Native Type I-F CRISPR-Cas System of Acinetobacter baumannii for Genome Editing and Gene Repression

INTRODUCTION

The rapid emergence of infections caused by multidrug-resistant Acinetobacter baumannii (A. baumannii) has posed a serious threat to global public health. It has therefore become important to obtain a deeper understanding of the mechanisms of multidrug resistance and pathogenesis of A. baumannii; however, there are still relatively few genetic engineering tools for this. Although A. baumannii possesses Type I-F CRISPR-Cas systems, they have not yet been used for genetic modifications.

METHODS

A single plasmid-mediated native Type I-F CRISPR-Cas system for gene editing and gene regulation in A. baumannii was developed. The protospacer adjacent motif sequence was identified as 5'-NCC-3' by analysis of the CRISPR array.

RESULTS

Through introduction of the RecAb homologous recombination system, the knockout efficiency of the oxyR gene significantly increased from 12.5% to 75.0% in A. baumannii. To investigate transcriptional inhibition by the Type I-F CRISPR system, the gene encoding its Cas2-3 nuclease was deleted and the native Type I-F Cascade effector was repurposed to regulate transcription of alcohol dehydrogenase gene adh4. The level of adh4 transcription was inhibited by up to 900-fold compared with the control. The Cascade transcriptional module was also successfully applied in a clinical Klebsiella pneumoniae isolate.

CONCLUSION

This study proposed a tool for future exploration of the genetic characteristics of A. baumannii or other clinical strains.

First Report of Antibiotic Resistance Markers cfiA and nim Among Bacteroides fragilis Group Strains in Ecuadorian Patients

In recent years, increasing resistance of Bacteroides fragilis to several antibiotics has been reported in different countries. The aim of this study was to evaluate the antibiotic resistance profiles of Bacteroides spp. isolated from clinical samples by phenotypic and molecular methods. A total of 40 nonrepetitive isolates of the B. fragilis group were studied from 2018 to 2019. The species was identified by API 20A system. The minimum inhibitory concentrations (MICs) were determined by Sensititre anaerobe MIC plate. The presence of the nim and cfiA genes was checked by conventional PCR. The association between genes and insertion sequence (IS) was performed by whole genome sequencing. Eleven isolates were categorized as metronidazole-resistant and only 2 isolates harbored the nim gene. Five isolates were imipenem-resistant, but cfiA gene was detected in two isolates. cfiA gene was closely related to the cfiA-4 allele and associated with IS614B. The nim gene was not related to any nim gene type and was considered a new variant named nimL. IS612 was found upstream of nimL gene. In view of the scarcity of data on B. fragilis, there is a need to surveil antibiotic resistance levels and molecular mechanisms to implement better antimicrobial therapies against this important group of bacteria.

Lemierre's Syndrome Under the Disguise of COVID-19 Pneumonia: A Case Report and Systematic Review

Lemierre's syndrome refers to septic thrombophlebitis caused by Fusobacterium necrophorum bacteremia. The incidence of Lemierre's syndrome has risen over the past two decades. This report describes a case of a 31-year-old woman presenting with multifocal pneumonia and uncomplicated parapneumonic effusion, considered as COVID-19 pneumonia initially, then found to have Lemierre's syndrome with Fusobacterium necrophorum bacteremia and right internal jugular vein thrombophlebitis. Her condition improved after four weeks of antibiotics without anticoagulation. The article summarized the history, epidemiology, clinical presentation, differential diagnosis, and treatment of Lemierre's syndrome, the rare but severe complication of bacterial infection. The article also summarized six reported Lemierre's syndrome cases during the COVID-19 pandemic to emphasize the significance of having a broad differential diagnosis for respiratory symptoms, especially in the COVID-19 era.

Biofilm-Forming Capacity and Drug Resistance of Different Gardnerella Subgroups Associated with Bacterial Vaginosis

Bacterial vaginosis (BV) is the most common infection of the lower reproductive tract among women of reproductive age. Recurrent infections and antibiotic resistance associated with biofilms remain significant challenges for BV treatment. Gardnerella species are commonly found in women with and without BV, indicating that genetic differences among Gardnerella isolates may distinguish pathogenic from commensal subgroups. This study isolated 11 Gardnerella strains from vaginal samples obtained from women with BV before or after treatment. The biofilm formation ability of each strain was examined by crystal violet staining. Eight strains were selected using phylogenetic analysis of the cpn60 sequences and classified as subgroups A (6/8), B (1/8), and D (1/8). The biofilm formation ability and antibiotic resistance profile of these strains was compared among the subgroups. Subgroup D had the strongest biofilm formation ability. Six of the planktonic strains exhibited resistance to the first-line BV drug, metronidazole, and one to clindamycin. Moreover, biofilm formation in vitro increased strain resistance to clindamycin. Two strains with strong biofilm ability, S20 and S23, and two with weak biofilm ability, S24 and S25, were selected for comparative genomic analysis. S20 and S23 were found to contain four key genes associated with biofilm formation and more genes involved in carbohydrate synthesis and metabolism than S24 and S25. Identifying differences in the expression of virulence factors between Gardnerella subgroups could inform the development of novel treatments for BV.

Recent Trends in Antimicrobial Resistance among Anaerobic Clinical Isolates

Anaerobic bacteria are normal inhabitants of the human commensal microbiota and play an important role in various human infections. Tedious and time-consuming, antibiotic susceptibility testing is not routinely performed in all clinical microbiology laboratories, despite the increase in antibiotic resistance among clinically relevant anaerobes since the 1990s. β-lactam and metronidazole are the key molecules in the management of anaerobic infections, to the detriment of clindamycin. β-lactam resistance is usually mediated by the production of β-lactamases. Metronidazole resistance remains uncommon, complex, and not fully elucidated, while metronidazole inactivation appears to be a key mechanism. The use of clindamycin, a broad-spectrum anti-anaerobic agent, is becoming problematic due to the increase in resistance rate in all anaerobic bacteria, mainly mediated by Erm-type rRNA methylases. Second-line anti-anaerobes are fluoroquinolones, tetracyclines, chloramphenicol, and linezolid. This review aims to describe the up-to-date evolution of antibiotic resistance, give an overview, and understand the main mechanisms of resistance in a wide range of anaerobes.

Comparison of Cefepime with Piperacillin/Tazobactam Treatment in Patients with Hospital-Acquired Pneumonia

Although cefepime and piperacillin/tazobactam are commonly prescribed for the treatment of hospital-acquired pneumonia (HAP), which one is the superior therapy remains unclear. Using Korean National Health Insurance Service data from January 2018 to December 2018, we compared the clinical outcomes of patients with HAP who were treated with cefepime and those treated with piperacillin/tazobactam. Data from 9955 adult patients with HAP, of whom 1502 (15%) received cefepime and 8453 (85%) received piperacillin/tazobactam, were retrieved for primary analysis. Tube feeding, suctioning, positioning care, and intensive care unit admission were more common among patients who received piperacillin/tazobactam. Treatment outcomes, including rates of in-hospital mortality, pneumonia-related readmission, and all-cause mortality within 6 months after discharge, were comparable between the two groups. In a subgroup analysis of data from patients who required tube feeding, the risk for in-hospital mortality was significantly higher among those who received cefepime (fully adjusted odds ratio, 1.43; 95% confidence interval, 1.04-1.97; p = 0.042). Treatment outcomes did not differ between patients who received cefepime and those who received piperacillin/tazobactam treatment, but among patients who were at risk for aspiration, such as those receiving tube feeding, those who received piperacillin/tazobactam had lower rates of in-hospital mortality.

Understanding antimicrobial susceptibility profile of Finegoldia magna: an insight to an untrodden path

BACKGROUND

Finegoldia magna (formerly known as Peptococcus magnus or Peptostreptococcus magnus) belonging to phylum Firmicutes, class Clostridia and genus Finegoldia, is the only species known to cause infections in human beings. Amongst Gram positive anaerobic cocci, F. magna is known to be the most virulent with a high pathogenic potential. Significant upsurge in antimicrobial resistance among anaerobes has been documented by various studies. F. magna is known to be susceptible to most of the anti-anaerobic antimicrobials, however, multidrug resistant strains are being reported in literature. The present study was undertaken to highlight the role of F. magna in clinical infections and to analyze their antimicrobial susceptibility patterns.

METHODS

The present study was conducted in a tertiary care teaching hospital in Southern India. 42 clinical isolates of F. magna recovered from diverse clinical infections between January 2011 to December 2015 were studied. These isolates were subjected to antimicrobial susceptibility testing against metronidazole, clindamycin, cefoxitin, penicillin, chloramphenicol and linezolid.

RESULTS

Among the 42 isolates studied, majority of them were revived from diabetic foot infections (31%) followed by necrotizing fasciitis (19%) and deep-seated abscesses (19%). All the F. magna isolates showed good in-vitro activity against metronidazole, cefoxitin, linezolid and chloramphenicol. Clindamycin and penicillin resistance were observed against 9.5% and 2.4% of the isolates respectively. However, β-lactamase activity was not detected.

CONCLUSION

The antimicrobial resistance among anaerobes varies from pathogen to pathogen and region to region. Hence, a deep understanding of resistance pattern is necessary for better management of clinical infections.

Phenotypic and Genotypic Correlation of Antimicrobial Susceptibility of Bacteroides fragilis: Lessons Learnt

Background Bacteroides fragilis is an opportunistic pathogen causing severe infections, including bacteremia. There have been increased reports of antimicrobial resistance in B. fragilis. However, phenotypic testing of susceptibility is time consuming and not cost effective for anaerobes. The present study investigates the correlation of phenotypic susceptibility with genotypic markers; to determine if these could be considered for deciding empirical therapy for B. fragilis. Material and methods Bacteroides fragilis isolates from various clinical samples including exudates, tissue, and body fluids were collected between November 2018 and January 2020 in the Department of Clinical Microbiology, Christian Medical College (CMC) Vellore. Species identification was done by Matrix Assisted Laser Desorption Ionization time of flight mass spectrometry (MALDI TOF) according to the manufacturer's instructions. A total number of 51 B. fragilis isolates were tested against metronidazole, clindamycin, piperacillin/tazobactam, and meropenem phenotypically by agar dilution method using Clinical & Laboratory Standards Institute (CLSI) 2019 guidelines and minimum inhibitory concentrations (MIC) were interpretated. The genotypic markers for antimicrobial resistance genes (nim, emrF, and cfiA) were studied by polymerase chain reaction (PCR) assay as per the standard protocol on all isolates to detect resistance genes. Results B. fragilis isolates in this study expressed 45%, 41%, and 16% phenotypic resistance to clindamycin, metronidazole, and meropenem, respectively, with least resistance to piperacillin/tazobactam (6%). Among the metronidazole resistant isolates, 52% harbored nim gene. Nim gene was also present in 76% (23/30) of the metronidazole susceptible isolates. Similarly, cfiA was present in all eight meropenem resistant isolates in addition to 22% (9/41) of the susceptible isolates. All cfiA negative isolates were phenotypically susceptible. Interestingly, 74% (17/23) of the clindamycin resistant isolates were positive for ermF. Conclusions Detection of a limited set of genes does not always correlate with phenotypic resistance to metronidazole and clindamycin due to the reported influence of insertion sequence (IS) elements, efflux, and other genetic determinants. Certainly, the absence of the cfiA gene can be employed to rule out meropenem resistance. However, redundant use of antibiotics such as meropenem along with metronidazole could be avoided for B. fragilis, which might otherwise elevate meropenem resistance. Recommendation of metronidazole requires prior phenotypic testing due to the reported 41% resistance.

First large-scale study of antimicrobial susceptibility data, and genetic resistance determinants, in Fusobacterium necrophorum highlighting the importance of continuing focused susceptibility trend surveillance

OBJECTIVES

The objective of the study was to explore antimicrobial resistance gene determinant, and phenotypic antibiotic susceptibility, data for Fusobacterium necrophorum from a collection of UK strains. Antimicrobial resistance genes detected in publicly available assembled whole genome sequences were investigated for comparison.

METHODS

Three hundred and eighty five F. necrophorum strains (1982-2019) were revived from cryovials (Prolab). Subsequent to sequencing (Illumina) and quality checking, 374 whole genomes were available for analysis. Genomes were interrogated, using BioNumerics (bioMérieux; v 8.1), for the presence of known antimicrobial resistance genes (ARGs). Agar dilution susceptibility results for 313 F. necrophorum isolates (2016-2021) were also examined.

RESULTS

The phenotypic data for the 313 contemporary strains demonstrated potential resistance to penicillin in three isolates, using EUCAST v 11.0 breakpoints, and 73 (23%) strains using v 13.0 analysis. All strains were susceptible to multiple agents using v 11.0 guidance other than clindamycin (n = 2). Employing v 13.0 breakpoints, metronidazole (n = 3) and meropenem (n = 13) resistance were also detected. The tet(O), tet(M), tet(40), aph(3')-III, ant(6)-la and bla_OXA-85 ARGs were present in publicly available genomes. tet(M), tet(32), erm(A) and erm(B) were found within the UK strains, with correspondingly raised clindamycin and tetracycline minimum inhibitory concentrations.

CONCLUSIONS

Susceptibility to antibiotics recommended for the treatment of F. necrophorum infections should not be assumed. With evidence of potential ARG transmission from oral bacteria, and the detection of a transposon-mediated beta-lactamase resistance determinant in F. necrophorum, surveillance of both phenotypic and genotypic antimicrobial susceptibility trends must continue, and increase.

Clinical significance and outcomes of Clostridium tertium bacteremia: analysis of 62 cases in neutropenic and non-neutropenic patients

The clinical significance of Clostridium tertium bacteremia is still uncertain. We evaluated the incidence, clinical characteristics, and outcomes of C. tertium bacteremia and identified differences between neutropenia and non-neutropenia. All adult patients with C. tertium bacteremia in a 2700-bed tertiary center between January 2004 and November 2021 were retrospectively enrolled. The first episode of C. tertium bacteremia in each patient was included in the analysis. Among 601 patients with Clostridium species bacteremia, 62 (10%) had C. tertium bacteremia, and of these 62 patients, 39 (63%) had had recent chemotherapy, and 31 (50%) had neutropenia or hematologic malignancy. C. tertium bacteremia originated frequently from a gastrointestinal tract infection such as enterocolitis (34%), primary bacteremia (29%), and secondary peritonitis (18%), and 34% of patients had polymicrobial bacteremia. Hematologic malignancy, prior antibiotic treatment, neutropenic enterocolitis, and primary bacteremia were significantly associated with C. tertium bacteremia in neutropenic patients, whereas solid tumor, hepatobiliary disease, secondary peritonitis, polymicrobial bacteremia, and a higher frequency of eradicable infection foci were significantly associated with C. tertium bacteremia in non-neutropenic patients. There was 15% 30-day mortality. APACHE II score (adjusted odds ratio [aOR], 1.5; 95% confidence interval [CI], 1.1-2.1) and secondary peritonitis (aOR, 25.9; 95% CI, 3.0-224.7) were independent risk factors for 30-day mortality. The prevalence of C. tertium bacteremia is low, and the characteristics of C. tertium bacteremia are significantly different between neutropenic and non-neutropenic patients. Appropriate investigation for gastrointestinal mucosal injury should be performed to improve treatment outcomes in this form of bacteremia.

Lemierre's Syndrome in the External Jugular Vein Precipitated by COVID-19 Infection

Lemierre's syndrome is a condition when an oropharyngeal infection, typically from Fusobacterium necrophorum, causes thrombophlebitis of the internal jugular vein. There have been few case reports of Lemierre's syndrome affecting the external jugular vein, but to our knowledge, this is the first case report where COVID-19 infection is the prime suspect for causing this syndrome. SARS-CoV-2 infection, known to cause hypercoagulability and immunosuppression, increases the risk of deep venous thrombosis and secondary infections. We report a case of a young male with no known risk factors who developed Lemierre's syndrome as a complication of COVID infection.

Virulence potential of antimicrobial-resistant extraintestinal pathogenic Escherichia coli from retail poultry meat in a Caenorhabditis elegans model

Healthy poultry can be a reservoir for extraintestinal pathogenic Escherichia coli (ExPEC), some of which could be multidrug resistant to antimicrobials. These ExPEC strains could contaminate the environment and/or food chain representing thus, food safety and human health risk. However, few studies have shown the virulence of poultry-source antimicrobial-resistant (AMR) ExPEC in humans. This study characterized AMR ExPEC and investigated the virulence potential of some of their isolates in a Caenorhabditis elegans infection model. A total of 46 E. coli isolates from poultry (chicken, n = 29; turkey, n = 12) retail meats and chicken feces (n = 4), or humans (n = 1) were sequenced and identified as ExPEC. Except eight, all remaining 38 ExPEC isolates were resistant to at least one antibiotic and carried corresponding antimicrobial resistance genes (ARGs). About 27 of the 46 ExPEC isolates were multidrug-resistant (≥3 antibiotic classes). Seven ExPEC isolates from chicken or turkey meats were of serotype O25:H4 and sequence type (ST) 131 which clustered with an isolate from a human urinary tract infection (UTI) case having the same serotype and ST. The C. elegans challenge model using eight of studied ExPEC isolates harboring various ARGs and virulence genes (VGs) showed that regardless of their ARG or VG numbers in tested poultry meat and feces, ExPEC significantly reduced the life span of the nematode (P < 0.05) similarly to a human UTI isolate. This study indicated the pathogenic potential of AMR ExPEC from retail poultry meat or feces, but more studies are warranted to establish their virulence in poultry and human. Furthermore, relationships between specific resistance profiles and/or VGs in these E. coli isolates for their pathogenicity deserve investigations.

Immunomodulatory Effects of Macrolides Considering Evidence from Human and Veterinary Medicine

Macrolide antimicrobial agents have been in clinical use for more than 60 years in both human and veterinary medicine. The discovery of the non-antimicrobial properties of macrolides and the effect of immunomodulation of the inflammatory response has benefited patients with chronic airway diseases and impacted morbidity and mortality. This review examines the evidence of antimicrobial and non-antimicrobial properties of macrolides in human and veterinary medicine with a focus toward veterinary macrolides but including important and relevant evidence from the human literature. The complete story for these complex and important molecules is continuing to be written.

Fluorescent metabolic labeling-based quick antibiotic susceptibility test for anaerobic bacteria

Because of the advancements in medicine and science, the numbers of patients surviving complicated diseases are continuously increasing, which in turn leads to elevated chances of anaerobic infections by endogenous bacteria. Traditional growth yield-based antibiotic susceptibility tests (ASTs) against anaerobic bacteria are very time-consuming (≥48 h) and labor intensive, which delays the timely guidance of antibiotic prescription and increases the mortality of patients. Inspired by a fluorescent d-amino acid (FDAA) labeling-based AST (FaAST) that we recently developed for quick determination of aerobic bacteria's susceptibilities, here we report an accurate and fast AST method for anaerobic pathogens. Based on flow cytometry analysis of anaerobes that have been treated with various doses of antibiotics and metabolically labeled with FDAA, the intensities of which can reflect their affected metabolic status by the drugs, the MICs of each drug can then be determined. The whole process can be completed in 5 h. After testing 40 combinations of the representative anaerobic bacteria and antibiotics, our method demonstrates a high susceptibility category accuracy of 95.0%. This FaAST-based protocol is helpful in accurately and quickly guiding antibiotic decisions when treating critical infections caused by anaerobic bacteria.

Efficient Suppression of Natural Plasmid-Borne Gene Expression in Carbapenem-Resistant Klebsiella pneumoniae Using a Compact CRISPR Interference System

There is an urgent need for efficient tools for genetic manipulation to assess plasmid function in clinical drug-resistant bacterial strains. To address this need, we developed an all-in-one CRISPR interference (CRISPRi) system that easily inhibited the gene expression of a natural multidrug-resistant plasmid in an sequence type 23 (ST23) Klebsiella pneumoniae isolate. We established an integrative CRISPRi system plasmid, pdCas9gRNA, harboring a dcas9 gene and a single guide RNA (sgRNA) unit under the control of anhydrotetracycline-induced and J23119 promoters, respectively, using a one-step cloning method. This system can repress the single resistance gene bla_NDM-1, with a >1,000-fold reduction in the meropenem MIC, or simultaneously silence the resistance genes bla_NDM-1 and bla_SHV-12, with a 16-fold and 8-fold respective reduction in the meropenem and aztreonam MIC on a large natural multidrug-resistant pNK01067-NDM-1 plasmid in an ST23 K. pneumoniae isolate. Furthermore, an sgRNA targeting the bla_NDM-1 promoter region can silence the entire bla_NDM-1-ble_MBL-trpF operon, confirming the existence of the operon. We also used this tool to knock down the multicopy resistance gene bla_KPC-2 in pathogenic Escherichia coli, increasing the susceptibility to meropenem. In a word, the all-in-one CRISPRi system can be used for efficient interrogation of indigenous plasmid-borne gene functions, providing a rapid, easy genetic manipulation tool for clinical K. pneumoniae isolates.

Metronidazole enhances killing of Porphyromonas gingivalis by human PMNs

Background and objectives

Periodontitis affects the supporting structures of the teeth as a result of the interactions between the subgingival biofilm and the host immune system. Periodontal therapy in severe forms of periodontitis often utilizes antimicrobial agents with some potential to improve host defense responses. In the present study, we investigated the in vitro effect of metronidazole (MTZ) at concentrations achievable in the periodontal pocket on PMN activation and PMN mediated killing of Porphyromonas gingivalis.

Materials and methods

Flow cytometry based assays were used to measure the impact of MTZ on PMN degranulation, neutrophil extracellular trap (NET) formation and myeloperoxidase (MPO) release and phagocytosis in response to the keystone oral pathogen P. gingivalis. Functional assays for PMN mediated killing of P. gingivalis and reactive oxygen species (ROS) production in PMN were also carried out.

Results

We demonstrate that PMNs pretreated with MTZ (2 μg/ml or 50 μg/ml) displayed enhanced killing of P. gingivalis compared to untreated PMNs. At concentrations achieved physiologically in the periodontal pocket, MTZ induced PMN surface expression of two activation markers (CD66 and CD63). MTZ did not alter P. gingivalis-induced NETosis, but suppressed P. gingivalis-induced ROS production and phagocytosis.

Conclusion

MTZ displays a positive interaction with PMNs to potentiate PMN mediated killing of P. gingivalis and may therefore contribute to its beneficial effects in the treatment of periodontitis initiated by P. gingivalis infections including those refractory to conventional treatment.

Serum cholesterol increase in statin users associated with antibiotic use: Case-crossover study

PURPOSE

3-hydroxy-3-methyl-glutaryl-coenzyme A (HMG-CoA) reductase inhibitors ("statins") reduce risk of atherosclerotic disease. However, statins need secondary bile acids, produced by the gut microbiota, for absorption. Our hypothesis was that a change in the gut microbiota induced by antibiotics might cause a decrease in statin absorption, and decreased statin effectiveness. Our objective was to study the association between antibiotic treatment and increased cholesterol level in statin users.

METHODS

Case-crossover study, in which an individual serves as his own control, by comparing outcome risk among the same individual at different times, adjusting for time-dependent comorbidity index. The study is based on adherent statin users' cohort and two cohorts of patients not treated with statins, in Clalit Health Services. Exposure were antibiotic prescriptions dispensed in the 3 months prior to LDL-C measurements.

RESULTS

There were 25,496 statin users and 72,638 time-points. A significant association was found between LDL-C increase and exposure to macrolides and clindamycin, OR = 1.237 (1.138-1.345), p = 6.5*10^-7, number needed to harm (NNH) = 19. There was no association between LDL-C increase and negative control objects such as anti-viral treatments; nor between LDL-C and exposure to antibiotics in non-statin users. As a secondary outcome, we have found an association between LDL-C increase and a following atherosclerotic ischemic event.

CONCLUSION

An increase in LDL-C in highly adherent statin users is associated with precedent macrolides or clindamycin treatment.

Identification and distribution of anaerobic bacteria isolated from clinical specimens in a University Hospital: 4 years’ experience

Anaerobes, which are components of microbiota, can cause life-threatening infections. Because of their fastidious nature, they are difficult to isolate and are often overlooked. The goal of this study was to identify the anaerobic bacteria isolated from clinical specimens at the Central Laboratory of Hacettepe University Hospital in 2015-2018 and to evaluate the distribution of the isolated bacterial species among the different specimen types. The anaerobic bacteria isolated from the specimens were identified by the conventional methods and MALDI-TOF MS.

Overall, 15,300 anaerobic cultures were studied. Of these, 14,434 (94.3%) were blood samples and 866 (5.7%) were other clinical specimens. A total of 138 anaerobic bacteria were isolated: 62 (44.9%) were isolated from blood samples and 76 (55.1%) from other specimens. The most isolated anaerobes from blood cultures were Bacteroides spp. (41.9%), followed by Cutibacterium acnes (25.8%) and Clostridium spp. (9.7%). The most isolated anaerobes from the other specimens were Gram-negative bacilli, including Bacteroides spp. (15.8%), Fusobacterium spp. (14.5%), Prevotella spp. (14.5%), and Porphyromonas spp. (2.6%). Anaerobic Finegoldia magna represented the major species among the isolated Gram-positive bacteria (10.5%). Anaerobic growth was observed in 0.4% of all the blood cultures and in 5.8% of the positive blood cultures. The results of our study showed that the incidence of anaerobic bacteremia was stable during the 2015-2018 period.

Time for Some Group Therapy: Update on Identification, Antimicrobial Resistance, Taxonomy, and Clinical Significance of the Bacteroides fragilis Group

Bacteroides fragilis group (BFG) species are common members of the human microbiota that provide several benefits to healthy hosts, yet BFG are also the most common anaerobes isolated from human infections, including intra-abdominal infections, abscesses, and bloodstream infection. Compared to many other anaerobes associated with disease, members of the BFG are more likely to be resistant to commonly used antimicrobials, including penicillin (>90% resistant), carbapenems (2 to 20% resistant), and metronidazole (0.2 to 4% resistant). As a result, infection with BFG bacteria can be associated with poor clinical outcomes. Here, we discuss the role of BFG in human health and disease, proposed taxonomic reclassifications within the BFG, and updates in methods for species-level identification. The increasing availability of whole-genome sequencing (WGS) supports recent proposals that the BFG now span two families (Bacteroidaceae and "Tannerellaceae") and multiple genera (Bacteroides, Parabacteroides, and Phocaeicola) within the phylum Bacteroidota. While members of the BFG are often reported to "group" rather than "species" level in many clinical settings, new reports of species-specific trends in antimicrobial resistance profiles and improved resolution of identification tools support routine species-level reporting in clinical practice. Empirical therapy may not be adequate for treatment of serious infections with BFG, warranting susceptibility testing for serious infections. We summarize methods for antimicrobial susceptibility testing and resistance prediction for BFG, including broth microdilution, agar dilution, WGS, and matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). We examine global trends in BFG antimicrobial resistance and review genomics of BFG, revealing insights into rapid activation and dissemination of numerous antimicrobial resistance mechanisms.

A Critical Review of the Antimicrobial and Antibiofilm Activities of Green-Synthesized Plant-Based Metallic Nanoparticles

Metallic nanoparticles (MNPs) produced by green synthesis using plant extracts have attracted huge interest in the scientific community due to their excellent antibacterial, antifungal and antibiofilm activities. To evaluate these pharmacological properties, several methods or protocols have been successfully developed and implemented. Although these protocols were mostly inspired by the guidelines from national and international regulatory bodies, they suffer from a glaring absence of standardization of the experimental conditions. This situation leads to a lack of reproducibility and comparability of data from different study settings. To minimize these problems, guidelines for the antimicrobial and antibiofilm evaluation of MNPs should be developed by specialists in the field. Being aware of the immensity of the workload and the efforts required to achieve this, we set out to undertake a meticulous literature review of different experimental protocols and laboratory conditions used for the antimicrobial and antibiofilm evaluation of MNPs that could be used as a basis for future guidelines. This review also brings together all the discrepancies resulting from the different experimental designs and emphasizes their impact on the biological activities as well as their interpretation. Finally, the paper proposes a general overview that requires extensive experimental investigations to set the stage for the future development of effective antimicrobial MNPs using green synthesis.

Microbial Resistance to Antibiotics and Effective Antibiotherapy

Currently, the efficacy of antibiotics is severely affected by the emergence of the antimicrobial resistance phenomenon, leading to increased morbidity and mortality worldwide. Multidrug-resistant pathogens are found not only in hospital settings, but also in the community, and are considered one of the biggest public health concerns. The main mechanisms by which bacteria develop resistance to antibiotics include changes in the drug target, prevention of entering the cell, elimination through efflux pumps or inactivation of drugs. A better understanding and prediction of resistance patterns of a pathogen will lead to a better selection of active antibiotics for the treatment of multidrug-resistant infections.

Anaerobic bloodstream infections in Italy (ITANAEROBY): A 5-year retrospective nationwide survey

INTRODUCTION

A lack of updated data on the burden and profile of anaerobic bloodstream infections (ABIs) exists. We assessed the incidence of ABIs and trends in antimicrobial resistance in anaerobes isolated from blood in Italy.

MATERIAL AND METHODS

We conducted a retrospective study on 17 Italian hospitals (2016-2020). Anaerobes isolated from blood culture and their in vitro susceptibility profiles (EUCAST-interpreted) were registered and analyzed.

RESULTS

A total of 1960 ABIs were identified. The mean age of ABIs patients was 68.6 ± 18.5 years, 57.6% were males. The overall incidence rate of ABIs was 1.01 per 10.000 patient-days. Forty-seven% of ABIs occurred in medical wards, 17% in ICUs, 14% in surgical wards, 7% in hemato-oncology, 14% in outpatients. The three most common anti-anaerobic tested drugs were metronidazole (92%), clindamycin (89%) and amoxicillin/clavulanate (83%). The three most common isolated anaerobes were Bacteroides fragilis (n = 529), Cutibacterium acnes (n = 262) and Clostridium perfringens (n = 134). The lowest resistance rate (1.5%) was to carbapenems, whereas the highest rate (51%) was to penicillin. Clindamycin resistance was >20% for Bacteroides spp., Prevotella spp. and Clostridium spp. Metronidazole resistance was 9.2% after excluding C. acnes and Actinomyces spp. Bacteroides spp. showed an increased prevalence of clindamycin resistance through the study period: 19% in 2016, 33% in 2020 (p ≤ 0.001).

CONCLUSIONS

Our data provide a comprehensive overview of the epidemiology of ABIs in Italy, filling a gap that has existed since 1995. Caution is needed when clindamycin is used as empirical anti-anaerobic drug.

Gut microbiome correlates of response and toxicity following anti-CD19 CAR T cell therapy

Anti-CD19 chimeric antigen receptor (CAR) T cell therapy has led to unprecedented responses in patients with high-risk hematologic malignancies. However, up to 60% of patients still experience disease relapse and up to 80% of patients experience CAR-mediated toxicities, such as cytokine release syndrome or immune effector cell-associated neurotoxicity syndrome. We investigated the role of the intestinal microbiome on these outcomes in a multicenter study of patients with B cell lymphoma and leukemia. We found in a retrospective cohort (n = 228) that exposure to antibiotics, in particular piperacillin/tazobactam, meropenem and imipenem/cilastatin (P-I-M), in the 4 weeks before therapy was associated with worse survival and increased neurotoxicity. In stool samples from a prospective cohort of CAR T cell recipients (n = 48), the fecal microbiome was altered at baseline compared to healthy controls. Stool sample profiling by 16S ribosomal RNA and metagenomic shotgun sequencing revealed that clinical outcomes were associated with differences in specific bacterial taxa and metabolic pathways. Through both untargeted and hypothesis-driven analysis of 16S sequencing data, we identified species within the class Clostridia that were associated with day 100 complete response. We concluded that changes in the intestinal microbiome are associated with clinical outcomes after anti-CD19 CAR T cell therapy in patients with B cell malignancies.

Minimum Contact Time of 1.25%, 2.5%, 5%, and 10% Benzoyl Peroxide for a Bactericidal Effect Against Cutibacterium acnes

Purpose

Benzoyl peroxide (BPO) is an effective acne treatment and has been used as a cleanser and short contact therapy. However, data on the minimum contact time of BPO needed to kill Cutibacterium acnes are lacking. Thus, the aim of this study was to determine the minimum contact time of commonly used BPO concentrations for bactericidal effects on C. acnes.

Materials and Methods

An in vitro experimental study of clinically isolated C. acnes was performed to determine the minimal inhibitory concentration (MIC) of BPO using the broth microdilution method. Subsequently, the minimum contact times of various concentrations of BPO were evaluated, and their bactericidal effects were assessed by the plate count method.

Results

The median MIC of BPO was 9375 µg/mL, which did not significantly differ between antibiotic-resistant and nonresistant C. acnes. The minimum contact time of BPO with C. acnes was significantly different among the BPO concentrations. For bactericidal activity against all isolates, 1.25%, 2.5%, 5%, and 10% BPO required 60 min, 15 min, 30 sec, and 30 sec, respectively.

Conclusion

BPO demonstrated bactericidal activity against both antibiotic-resistant and antibiotic-susceptible C. acnes. The in vitro contact time needed to kill C. acnes was almost immediate with 5% or more BPO, but ≤ 2.5% BPO required longer contact times for bactericidal effects.

Incidence of Vancomycin-Resistant Staphylococcus aureus Strains among Patients with Urinary Tract Infections

There has been a substantial rise in the number of vancomycin-resistant Staphylococcus aureus (VRSA) strains during the last several years. The proportion of vancomycin-resistant strains among isolated S. aureus has risen steadily in recent years, with the first spike occurring in critical care units and thereafter in general hospital wards. S. aureus isolates from urinary tract infection patients were studied for their prevalence and antibiotic resistance. From 292 urine samples, 103 bacterial strains (35.3%) were identified as S. aureus. Various antibiotics were used to test the isolates’ antibacterial resistance profiles. Antibiotic resistance to erythromycin was found in most bacterial isolates, whereas tobramycin antibiotic sensitivity was found in most of them. Vancomycin resistance was found in 23 of all S. aureus isolates in this study. Analysis for β-lactamase found that 71% of S. aureus isolates were positive in all isolates. There was a single plasmid with a molecular weight of 39.306 Kbp in five selected VRSA isolates that was subjected to plasmid analysis. There was evidence of vancomycin resistance among the S. aureus isolates collected from UTI patients in this investigation. This vancomycin resistance pretenses a challenge in the treatment of S. aureus infections and the need to precisely recognize persons who require last-resort medication such as tobramycin.

Comparative Proteomic Analysis of Fucosylated Glycoproteins Produced by Bacteroides thetaiotaomicron Under Different Polysaccharide Nutrition Conditions

Bacteroides thetaiotaomicron, one of the most eminent representative gut commensal Bacteroides species, is able to use the L-fucose in host-derived and dietary polysaccharides to modify its capsular polysaccharides and glycoproteins through a mammalian-like salvage metabolic pathway. This process is essential for the colonization of the bacteria and for symbiosis with the host. However, despite the importance of fucosylated proteins (FGPs) in B. thetaiotaomicron, their types, distribution, and functions remain unclear. In this study, the effects of different polysaccharide (corn starch, mucin, and fucoidan) nutrition conditions on newly synthesized FGPs expressions and fucosylation are investigated using a chemical biological method based on metabolic labeling and bioorthogonal reaction. According to the results of label-free quantification, 559 FGPs (205 downregulated and 354 upregulated) are affected by the dietary conditions. Of these differentially expressed proteins, 65 proteins show extremely sensitive to polysaccharide nutrition conditions (FGPs fold change/global protein fold change ≥2.0 or ≤0.5). Specifically, the fucosylation of the chondroitin sulfate ABC enzyme, Sus proteins, and cationic efflux system proteins varies significantly upon the addition of mucin, corn starch, or fucoidan. Moreover, these polysaccharides can trigger an appreciable increase in the fucosylation level of the two-component system and ammonium transport proteins. These results highlight the efficiency of the combined metabolic glycan labeling and bio-orthogonal reaction in enriching the intestinal Bacteroides glycoproteins. Moreover, it emphasizes the sensitivity of Bacteroides fucosylation to polysaccharide nutrition conditions, which allows for the regulation of bacterial growth.

Clinical Differences in Patients Infected with Fusobacterium and Antimicrobial Susceptibility of Fusobacterium Isolates Recovered at a Tertiary-Care Hospital in Korea

Background

Fusobacterium species are obligately anaerobic, gram-negative bacilli. Especially, F. nucleatum and F. necrophorum are highly relevant human pathogens. We investigated clinical differences in patients infected with Fusobacterium spp. and determined the antimicrobial susceptibility of Fusobacterium isolates.

Methods

We collected clinical data of 86 patients from whom Fusobacterium spp. were isolated from clinical specimens at a tertiary-care hospital in Korea between 2003 and 2020. In total, 76 non-duplicated Fusobacterium isolates were selected for antimicrobial susceptibility testing by the agar dilution method, according to the Clinical and Laboratory Standards Institute guidelines (M11-A9).

Results

F. nucleatum was most frequently isolated from blood cultures and was associated with hematologic malignancy, whereas F. necrophorum was mostly prevalent in head and neck infections. Anti-anaerobic agents were more commonly used to treat F. nucleatum and F. varium infections than to treat F. necrophorum infections. We observed no significant difference in mortality between patients infected with these species. All F. nucleatum and F. necrophorum isolates were susceptible to the antimicrobial agents tested. F. varium was resistant to clindamycin (48%) and moxifloxacin (24%), and F. mortiferum was resistant to penicillin G (22%) and ceftriaxone (67%). β-Lactamase activity was not detected.

Conclusions

Despite the clinical differences among patients with clinically important Fusobacterium infections, there was no significant difference in the mortality rates. Some Fusobacterium spp. were resistant to penicillin G, ceftriaxone, clindamycin, or moxifloxacin. This study may provide clinically relevant data for implementing empirical treatment against Fusobacterium infections.

Neuronal NR4A1 deficiency drives complement-coordinated synaptic stripping by microglia in a mouse model of lupus

Neuropsychiatric lupus (NPSLE) is a frequent manifestation of systemic lupus erythematosus (SLE) that occurs in 40–90% of SLE patients; however, the underlying mechanisms remain elusive, causing a severe lack of therapeutic targets for this condition. Here, we show that complement-coordinated elimination of synapses participated in NPSLE in MRL/lpr mice, a lupus-prone murine model. We demonstrated that lupus mice developed increased anxiety-like behaviors and persistent phagocytic microglial reactivation before overt peripheral lupus pathology. In the lupus brain, C1q was increased and localized at synaptic terminals, causing the apposition of phagocytic microglia and ensuing synaptic engulfment. We further determined that neuronal Nr4a1 signaling was essential for attracting C1q synaptic deposition and subsequent microglia-mediated synaptic elimination. Minocycline-mediated deactivation of microglia, antibody blockade of C1q, or neuronal restoration of Nr4a1 protected lupus mice from synapse loss and NP manifestations. Our findings revealed an active role of neurons in coordinating microglia-mediated synaptic loss and highlighted neuronal Nr4a1 and C1q as critical components amenable to therapeutic intervention in NPSLE.

Association of Exposure to High-risk Antibiotics in Acute Care Hospitals With Multidrug-Resistant Organism Burden in Nursing Homes

IMPORTANCE

Little is known about the contribution of hospital antibiotic prescribing to multidrug-resistant organism (MDRO) burden in nursing homes (NHs).

OBJECTIVES

To characterize antibiotic exposures across the NH patient's health care continuum (preceding health care exposure and NH stay) and to investigate whether recent antibiotic exposure is associated with MDRO colonization and room environment contamination at NH study enrollment.

DESIGN, SETTING, AND PARTICIPANTS

This is a secondary analysis of a prospective cohort study (conducted from 2013-2016) that enrolled NH patients and followed them up for as long as 6 months. The study was conducted in 6 NHs in Michigan among NH patients who were enrolled within 14 days of admission. Clinical metadata abstraction, multi-anatomical site screening, and room environment surveillance for MDROs were conducted at each study visit. Data were analyzed between May 2019 and November 2021.

EXPOSURES

Antibiotic data were abstracted from NH electronic medical records by trained research staff and characterized by class, route, indication, location of therapy initiation, risk for Clostridioides difficile infection (C diffogenic agents), and 2019 World Health Organization Access, Watch, and Reserve (AWARE) antibiotic stewardship framework categories.

MAIN OUTCOMES AND MEASURES

The primary outcomes were MDRO colonization and MDRO room environment contamination at NH study enrollment, measured using standard microbiology methods. Multivariable logistic regression was used to identify whether antibiotic exposure within 60 days was associated with MDRO burden at NH study enrollment. Additionally, antibiotic exposure data were characterized using descriptive statistics.

RESULTS

A total of 642 patients were included (mean [SD] age, 74.7 [12.2] years; 369 [57.5%] women; 402 [62.6%] White; median [IQR] NH days to enrollment, 6.0 [3.0-7.0]). Of these, 422 (65.7%) received 1191 antibiotic exposures: 368 (57.3%) received 971 hospital-associated prescriptions, and 119 (18.5%) received 198 NH-associated prescriptions. Overall, 283 patients (44.1%) received at least 1 C diffogenic agent, and 322 (50.2%) received at least 1 high-risk WHO AWARE antibiotic (watch or reserve agent). More than half of NH patients (364 [56.7%]) and room environments (437 [68.1%]) had MDRO-positive results at enrollment. In multivariable analysis, recent antibiotic exposure was positively associated with baseline MDRO colonization (odds ratio [OR], 1.70; 95% CI, 1.22-2.38) and MDRO environmental contamination (OR, 1.67; 95% CI, 1.17-2.39). Exploratory stratification by C diffogenic agent exposure increased the effect size (MDRO colonization: OR, 1.99; 95% CI, 1.33-2.96; MDRO environmental contamination: OR, 1.86; 95% CI, 1.24-2.79). Likewise, exploratory stratification by exposure to high-risk WHO AWARE antibiotics increased the effect size (MDRO colonization: OR, 2.32; 95% CI, 1.61-3.36; MDRO environmental contamination: OR, 1.86; 95% CI, 1.26-2.75).

CONCLUSIONS AND RELEVANCE

The findings of this study suggest that high-risk, hospital-based antibiotics are a potentially high-value target to reduce MDROs in postacute care NHs. This study underscores the potential utility of integrated hospital and NH stewardship programming on regional MDRO epidemiology.

An evidence-based approach to antibiotic use in maxillofacial trauma

A patient with craniomaxillofacial (CMF) trauma often receives consultations from multiple medical and surgical services. Antibiotics are sometimes prescribed without consistent evidence. This article reviews current literature regarding antibiotic prophylaxis of patients with CMF fractures. This article also presents the guidelines for the appropriate use of antibiotics for patients with CMF fractures at 2 level I trauma centers.