Antimicrobial Classes Research Articles

Antimicrobial resistance in Enterococcus isolated from western Canadian cow-calf herds

BackgroundData on antimicrobial resistance (AMR) in cow-calf herds is limited and there have been no Canadian studies examining AMR in Enterococcus in cow-calf herds. Enterococcus is a ubiquitous Gram-positive indicator of AMR for enteric organisms that is also important in human health. The objective of this study was to describe AMR in specific Enterococcus species of interest from cow-calf herds; highlighting differences in AMR among isolates from cows and calves and samples collected in the spring and fall. Isolates (n = 1505) were examined from 349 calves and 385 cows from 39 herds in the spring of 2021 and 413 calves from 39 herds and 358 cows from 36 herds in the fall of 2021. Enterococcus species were identified using Matrix-Assisted Laser Desorption Ionization Time-Of-Flight mass spectrometry (MALDI-TOF MS) and antimicrobial susceptibility testing was completed based on a prioritization scheme for importance to human health and using the National Antimicrobial Resistance Monitoring System (NARMS) Gram positive Sensititre broth microdilution panel.ResultsResistance was observed to at least one antimicrobial in 86% (630/734) of isolates from the spring and 84% (644/771) of isolates from the fall. The most common types of resistance across all species were: lincomycin, quinupristin/dalfopristin, daptomycin, ciprofloxacin, and tetracycline. However, the proportion of isolates with AMR varied substantially based on species. Multiclass resistance, defined as resistance to ≥3 antimicrobial classes after excluding intrinsic resistance, was highest in isolates from calves in the spring (6.9%) (24/349) and cows in the fall (6.7%) (24/357). Differences in resistance were seen between cows and calves in the spring and fall as well as across seasons, with no differences seen between cows and calves in the fall.ConclusionsWhile most Enterococcus isolates were resistant to at least one antimicrobial, questions remain regarding species differences in intrinsic resistance and the accuracy of certain antimicrobial breakpoints for specific Enterococcus spp. As a result, some species-specific AMR profiles should be interpreted with caution. Despite these constraints, Enterococcus species are important indicator organisms for AMR and resulting data can be used to inform stewardship initiatives.

P26 A life threatening case of Von Zumbusch psoriasis

Abstract We report a case of a patient admitted to intensive care with a pustulating skin eruption and haemodynamic compromise with near immediate response to infliximab. A 16-year-old male with a six-month history of mild plaque psoriasis presented to acute dermatology services with widespread annular pustular eruption, which developed days after a throat infection. Histopathology was consistent with pustular psoriasis. After an initial partial response, the pustules spread and persisted despite 2-month treatment with topical steroids and ciclosporin (dosed to 4 mg/kg). With raised inflammatory markers and repeated growth of Staphylococcus aureus, high dose intravenous flucloxacillin was administered. Four hours post infusion the patient became erythrodermic and haemodynamically unstable, requiring management in ICU. Repeat skin biopsy showed features of psoriasis without clear drug reaction features. Switching classes of antimicrobials and administration of intravenous immunoglobulins led to infection resolution but no significant clinical status change. A multi-disciplinary decision was made to trial intravenous infliximab. This resulted in near-immediate 90% improvement of skin and haemodynamic status. His excellent clinical response has been maintained on adalimumab thus far. Genetic screening for possible mutations associated with pustular psoriasis, including IL36RN and CARD14, are in process.

Assessment of Antibiotic Resistance among Clinical Isolates of Enterobacteriaceae in Nepal.

Clinicians face a global challenge treating infections caused by Enterobacteriaceae because of the high rate of antibiotic resistance. This cross-sectional study from the Nepal Armed Police Force Hospital, Kathmandu, Nepal, characterized resistance patterns in Enterobacteriaceae across different antimicrobial classes and assessed incidences of multidrug-resistant (MDR) and extensively drug-resistant (XDR) infections. Enterobacteriaceae from clinical samples were isolated on blood and MacConkey agar, except for urine samples on cysteine lactose electrolyte-deficient agar. To determine antimicrobial susceptibility patterns, including MDR and XDR, the Kirby-Bauer disc diffusion method was used. Statistics were performed using SPSS, v. 17.0. Members of the family were identified in 14.5% (95% CI: 16.2-12.8%) of the total samples (N = 1,617), primarily in urine (54.7%, 128/234), blood (19.7%, 46/234), and sputum (15.0%, 35/234). Escherichia coli (n = 118, 44.2%) was the most predominant bacteria, followed by Citrobacter freundii (n = 81, 30.3%). As much as 95.6% (392/410) of the isolates were penicillin-resistant, whereas only 36.2% (290/801) were carbapenem-resistant. A total of 96 (36.0%) MDR and 98 (36.7%) XDR Enterobacteriaceae were identified. Proteus mirabilis (44.4%, 8/18) predominated MDR cultures, whereas C. freundii (53.1%, 43/81) predominated XDR cultures. Multidrug resistant (38.4%, 71/154) and XDR Enterobacteriaceae (22.7%, 35/154) were chiefly uropathogens. Fluoroquinolone resistance rates in non-MDR, MDR, and XDR isolates were 19.9%, 63.2%, and 96.2%, respectively, whereas cephalosporin resistance rates were 28.6%, 72.9%, and 95.4% and penicillin resistance rates were 67.0%, 97.4%, and 98.0%. One-seventh of patients visiting the hospital were found to be infected with Enterobacteriaceae, and of these patients, at least one-fourth were infected with MDR strains.

Antimicrobial Susceptibility Patterns and Genetic Diversity of Campylobacter spp. Isolates from Patients with Diarrhea in South Korea.

This study aimed to characterize the latest antimicrobial resistance patterns and genetic diversity of Campylobacter spp. isolated from patients with acute diarrhea in Korea. In total, 371 clinical isolates (361 Campylobacter jejuni and 10 Campylobacter coli) were collected from patients with diarrhea in 106 medical institutions of six provinces during the seasonal peak (April-September 2022) in South Korea. We then assessed their antimicrobial susceptibility to eight antimicrobial agents and performed multilocus sequence typing (MLST). This study investigated the antimicrobial resistance (AMR) profiles to tetracycline (32.3%), nalidixic acid (64.9%), and ciprofloxacin (83.3%), confirming high levels of the latter even after its Korean ban in 2010. However, tetracycline resistance displayed a decreasing trend. Alternatively, significantly lower resistance rates to clindamycin (0.8%), azithromycin (0.53%), erythromycin (0.53%), and gentamicin (0.53%) as well as absolute susceptibility to florfenicol (0%) were observed. Four C. jejuni and three C. coli isolates (7/371, 1.88%) were classified as multidrug-resistant (MDR) to at least three antimicrobial classes. MLST identified a high genetic diversity with 21 clonal complexes (CCs) and sixty-six sequence types (STs), including eight novel STs. The high CC frequency of C. jejuni comprised CC21 (37.7%), CC22 (13.8%), and CC206 (9.4%), while C. coli was predominated by CC828 (90%). The high CC21 and CC828 strain prevalence in this study was consistent with their worldwide distribution. This study highlights that quinolone- and tetracycline-resistant Campylobacter circulate in Korea with diverse genotypes, providing important information that could contribute to controlling and preventing increasing antimicrobial resistance in patients.

Engineering the interaction of short antimicrobial peptides with bacterial barriers

Designing short antimicrobial peptides and tuning their interaction with bacterial barriers.

Nationwide Analysis of Antimicrobial Prescription in Korean Hospitals between 2018 and 2021: The 2023 KONAS Report.

Data on antimicrobial use at the national level are crucial for establishing domestic antimicrobial stewardship policies and enabling medical institutions to benchmark each other. This study aimed to analyze antimicrobial use in Korean hospitals. We investigated antimicrobials prescribed in Korean hospitals between 2018 and 2021 using data from the Health Insurance Review and Assessment. Primary care hospitals (PCHs), secondary care hospitals (SCHs), and tertiary care hospitals (TCHs) were included in this analysis. Antimicrobials were categorized according to the Korea National Antimicrobial Use Analysis System (KONAS) classification, which is suitable for measuring antimicrobial use in Korean hospitals. Among over 1,900 hospitals, PCHs constituted the highest proportion, whereas TCHs had the lowest representation. The most frequently prescribed antimicrobials in 2021 were piperacillin/β-lactamase inhibitor (9.3%) in TCHs, ceftriaxone (11.0%) in SCHs, and cefazedone (18.9%) in PCHs. Between 2018 and 2021, the most used antimicrobial classes according to the KONAS classification were 'broad-spectrum antibacterial agents predominantly used for community-acquired infections' in SCHs and TCHs and 'narrow spectrum beta-lactam agents' in PCHs. Total consumption of antimicrobials decreased from 951.7 to 929.9 days of therapy (DOT)/1,000 patient-days in TCHs and 817.8 to 752.2 DOT/1,000 patient-days in SCHs during study period; however, no reduction was noted in PCHs (from 504.3 to 527.2 DOT/1,000 patient-days). Moreover, in 2021, the use of reserve antimicrobials decreased from 13.6 to 10.7 DOT/1,000 patient-days in TCHs and from 4.6 to 3.3 DOT/1,000 patient-days in SCHs. However, in PCHs, the use increased from 0.7 to 0.8 DOT/1,000 patient-days. This study confirmed that antimicrobial use differed according to hospital type in Korea. Recent increases in the use of total and reserve antimicrobials in PCHs reflect the challenges that must be addressed.

Association between antimicrobial usage and resistance on commercial broiler and layer farms in Bangladesh.

Antimicrobial resistance has emerged as a significant health problem worldwide, including in Bangladesh, where chickens are an important protein source for human nutrition. One of the factors accelerating the development of antimicrobial resistance is the inappropriate use of antimicrobials on commercial chicken farms. A cross-sectional study was conducted in 2019 on 140 commercial chicken farms in the Chattogram district of Bangladesh to investigate the association between antimicrobial use and resistance in Escherichia coli and Salmonella spp. cultured from cloacal swabs of chickens and from the poultry shed environment. All E. coli and Salmonella spp. isolates were resistant to multiple antimicrobial classes, including those categorized as "Highest Priority Critically Important Antimicrobials" for human medicine. Notably, resistance was observed in E. coli isolates from farms that did not use these antimicrobial classes in the current production cycle. For example, although quinolones were not used on 43.9% of E. coli positive farms, 95.7% of these farms had quinolone-resistant E. coli isolates. The results of the path analysis revealed that there was a "direct effect" of the frequency of antimicrobial usage on "high" resistance, with resistance increasing when antimicrobials were administered more frequently (β = 0.28, p = 0.002). There was a "direct effect" of the purpose of antimicrobial use on "low" resistance, with resistance marginally decreasing when antimicrobials were administered solely for therapeutic use (β = -0.17, p = 0.062), but increasing when they were used prophylactically. Overall, the study results could be used to educate farmers on better practices for antimicrobial administration, and to guide government agencies to update policies on antimicrobial use and resistance surveillance in the poultry sector of Bangladesh.

Single-cell multi-omics reveal stage of differentiation and trajectory-dependent immunity-related gene expression patterns in human erythroid cells.

The role of Erythroid cells in immune regulation and immunosuppression is one of the emerging topics in modern immunology that still requires further clarification as Erythroid cells from different tissues and different species express different immunoregulatory molecules. In this study, we performed a thorough investigation of human bone marrow Erythroid cells from adult healthy donors and adult acute lymphoblastic leukemia patients using the state-of-the-art single-cell targeted proteomics and transcriptomics via BD Rhapsody and cancer-related gene copy number variation analysis via NanoString Sprint Profiler. We found that human bone marrow Erythroid cells express the ARG1, LGALS1, LGALS3, LGALS9, and C10orf54 (VISTA) immunosuppressive genes, CXCL5, CXCL8, and VEGFA cytokine genes, as well as the genes involved in antimicrobial immunity and MHC Class II antigen presentation. We also found that ARG1 gene expression was restricted to the single erythroid cell cluster that we termed ARG1-positive Orthochromatic erythroblasts and that late Erythroid cells lose S100A9 and gain MZB1 gene expression in case of acute lymphoblastic leukemia. These findings show that steady-state erythropoiesis bone marrow Erythroid cells express myeloid signature genes even without any transdifferentiating stimulus like cancer.

Capping motifs in antimicrobial peptides and their relevance for improved biological activities.

N-capping (N-cap) and C-capping (C-cap) in biologically active peptides, including specific amino acids or unconventional group motifs, have been shown to modulate activity against pharmacological targets by interfering with the peptide's secondary structure, thus generating unusual scaffolds. The insertion of capping motifs in linear peptides has been shown to prevent peptide degradation by reducing its susceptibility to proteolytic cleavage, and the replacement of some functional groups by unusual groups in N- or C-capping regions in linear peptides has led to optimized peptide variants with improved secondary structure and enhanced activity. Furthermore, some essential amino acid residues that, when placed in antimicrobial peptide (AMP) capping regions, are capable of complexing metals such as Cu2+, Ni2+, and Zn2+, give rise to the family known as metallo-AMPs, which are capable of boosting antimicrobial efficacy, as well as other activities. Therefore, this review presents and discusses the different strategies for creating N- and C-cap motifs in AMPs, aiming at fine-tuning this class of antimicrobials.

Salmonella in Coastal Birds in Chile: Detection of a Multidrug‐Resistant S. Infantis Bearing the blaCTX-M−65 Gene in a pESI‐Like Megaplasmid in Humboldt Penguins

Salmonella enterica is one of the most important foodborne pathogens worldwide, and the emergence of multidrug resistance (MDR) clones can aggravate its public health importance. Wildlife species may act as reservoirs of these clones, but their role is not well understood. In this study, faecal samples from shorebirds, with a focus on the endangered Humboldt penguin (Spheniscus humboldti), collected from five sites in central Chile with different levels of anthropogenic pressure were analysed to characterize antimicrobial resistant S. enterica serovars. Overall, Salmonella was isolated from 22 of the 595 samples (3.7%), with positivity ranging between 1.6% and 9.5%, depending on the sampling site. Four of the Salmonella isolates were retrieved from Humboldt penguin samples (1.4% positive samples in this species). Serovars Infantis (nine isolates), Typhimurium (six), Goldcoast (four), and Enteritidis, Agona, and Give (one isolate each) were identified. Resistance levels were the highest for sulphamethoxazole (13/21 isolates with a non‐wild‐type phenotype), ciprofloxacin, tetracycline, and trimethoprim (11/21 each). Whole‐genome sequencing performed on eight S. Infantis strains revealed that seven carried the plasmid replicon IncFIB (pN55391), indicating the presence of the pESI‐like megaplasmid, harbouring resistance determinants to multiple antimicrobial classes as well as heavy metal, biocides, and virulence‐related genes. Furthermore, five S. Infantis isolates that showed an ESBL phenotype carried the blaCTX-M−65 gene, three of which were detected in Humboldt penguin faeces. The finding of an international emerging S. Infantis clone in protected wildlife is of concern to environmental, animal, and public health specialists, supporting initiatives for an active surveillance of resistance and virulence traits in wildlife exposed to anthropogenic areas.

The effect of ciprofloxacin prophylaxis during haematopoietic cell transplantation on infection episodes, exposure to treatment antimicrobials and antimicrobial resistance: a single-centre retrospective cohort study.

Fluroquinolone prophylaxis during haematopoietic cell transplantation (HCT) remains contentious. We aimed to determine its effectiveness and association with exposure to treatment antimicrobials and antimicrobial resistance. All admission episodes for HCT (N = 400 , 372 unique patients) in a tertiary centre between January 2020 and December 2022 were studied. Allogeneic HCT (allo-HCT) recipients received prophylaxis with ciprofloxacin during chemotherapy-induced neutropenia, while autologous HCT (auto-HCT) recipients did not. Allo-HCT was performed for 43.3% (173/400) of patients, auto-HCT for 56.7% (227/400). Allo-HCT was associated with an average of 1.01 fewer infection episodes per 100 admission days (95% CI 0.62-1.40, P < 0.001) compared with auto-HCT. In allo-HCT, the total exposure to all antimicrobials was higher [+24.8 days of therapy (DOT)/100 admission days, P < 0.001], as was exposure to ciprofloxacin (+40.5 DOT/100 admission days, P < 0.001). By contrast, exposure to meropenem (-4.5 DOT/100 admission days, P = 0.02), piperacillin/tazobactam (-5.2 DOT/100 admission days, P < 0.001), aminoglycosides (-4.5 DOT/100 admission days, P < 0.001) and glycopeptides (-6.4 DOT/100 admission days, P < 0.001) was reduced. Enterobacteriaceae isolated during allo-HCT were more resistant to ciprofloxacin (65.5%, 19/29 versus 6.1%, 2/33, P < 0001), ceftriaxone (65.5%, 19/29 versus 9.1%, 3/33, P < 0.001), other antimicrobial classes. Vancomycin-resistant enterococci were more common in allo-HCT recipients (11%, 19/173 versus 0.9%, 2/227, P < 0.001). Inpatient mortality during allo- and auto-HCT was 9.8% (17/173) and 0.4% (1/227). respectively (P < 0.001). Ciprofloxacin prophylaxis in allo-HCT was associated with fewer infection episodes and reduced exposure to treatment antimicrobials. Mortality in auto-HCT remained low. A significant burden of antimicrobial resistance was detected in allo-HCT recipients.

Circular intermediate-mediated horizontal transfer of the chromosome-encoded cfr(C) gene in multi-drug resistant Campylobacter coli from swine sources.

Campylobacter is a major zoonotic pathogen that causes gastrointestinal and, rarely, immune diseases in humans. The antimicrobial-resistance gene cfr(C) carried by Campylobacter and is a cfr-like gene that targets bacterial 23S rRNA through A2503 methylation. cfr(C) confers cross-resistance to five antimicrobial classes (PhLOPSA), including lincosamide, streptogramin A, and pleuromutilin, which are classified as critically important antimicrobials to human by the World Health Organization. To elucidate the genetic variation and horizontal transfer mechanism of cfr(C), we analyzed the genetic background and horizontal transfer unit of Campylobacter-derived cfr(C) through comparative genomic analysis. We identified nine cfr(C)-positive C. coli strains of 157 strains isolated from swine sources. Three novel cfr(C) gene single nucleotide polymorphism (SNP) sites (19delA, 674C > A, and 890 T > C) were identified from nine cfr(C)-positive strains. Among six identified cfr(C) SNP variant types (SNP-I to -VI), five types of randomly inserted cfr(C)-cassettes on chromosome and one type of plasmid-like element were identified, their gene cassette composition differing depending on the cfr(C) variants. Three of six cfr(C) cassette types contained aminoglycoside-streptothricin resistance cluster "aphA3-sat4-aadE." The cfr(C) gene cassette with pcp gene (GC-1, GC-4, and GC-5) formed a pcp-mediated circular intermediate "pcp-hp-cfr(C)-aphA3," which has not been previously reported. Other two cfr(C) cassette-types with ISChh1 formed circular intermediate "ISChh1-aphA3-cfr(C)-lnu (G)-pnp-ant1-hp-ATPase" and "ISChh1-aphA3-cfr(C)-hp." In conjugation assay, the pcp-mediated circular intermediate was naturally transferred to the plasmid of recipient C. coli wild-type strain from swine source, and comparative genomic analysis revealed that cfr(C) encoded in pcp-mediated circular intermediate was inserted into the plasmid of recipient by homologous recombination with pcp and aphA3. This study revealed that novel multidrug resistance gene cfr(C) carried by C. coli from swine sources can be highly genetically diverse and transferable. Moreover, we suggest that the transferability of chromosomal cfr(C) may contribute to the global spread of multidrug resistance against clinically important antimicrobials.

Prevalence and antimicrobial resistance profiles of extended-spectrum beta-lactamase-producing Escherichia coli in East Tennessee dairy farms.

The extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae, such as Escherichia coli, are emerging as a serious threat to global health due to their rapid spread and their multidrug-resistant (MDR) phenotypes. However, limited information is available regarding the prevalence and antimicrobial resistance (AMR) profile of ESBL-E. coli in the United States dairy farms. This study aimed to determine the prevalence and AMR pattern of ESBL-E. coli in East Tennessee dairy cattle farms. Rectal fecal samples from dairy cattle (n = 508) and manure (n = 30), water (n = 19), and feed samples (n = 15) were collected from 14 farms. The presumptive E. coli was isolated on CHROMagar™ ESBL and confirmed by matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS). Antimicrobial susceptibility testing was performed on the ESBL-E. coli isolates. From 572 fecal and farm environmental samples, a total of 233 (41%, n = 572) ESBL-E. coli were identified. The prevalence of fecal ESBL-E. coli was 47.5% (95% CI: 46.2-49.2). The within-farm prevalence of ESBL-E. coli ranged from 8 to 100%. Recent treatment history with third-generation cephalosporins (3GC), cow parity ≥3, and calves were the independent risk factors associated (P < 0.05) with fecal carriage of ESBL-E. coli. Overall, 99.6% (n = 231) ESBL-E. coli tested were phenotypically resistant to at least one of the 14 antimicrobial agents tested. The most common AMR phenotypes were against beta-lactam antibiotics, ampicillin (99.1%; n = 231 isolates), and ceftriaxone (98.7%, n = 231). Most ESBL-E. coli isolates (94.4%) were MDR (resistance to ≥3 antimicrobial classes), of which 42.6% showed co-resistance to at least six classes of antimicrobials. ESBL-E. coli isolates with concurrent resistance to ceftriaxone, ampicillin, streptomycin, tetracycline, sulfisoxazole, and chloramphenicol are widespread and detected in all the farms. The detection of MDR ESBL-E. coli suggests that dairy cattle can be a reservoir for these bacteria, highlighting the associated public health risk.

Commensal production of a broad-spectrum and short-lived antimicrobial peptide polyene eliminates nasal Staphylococcus aureus

Antagonistic bacterial interactions often rely on antimicrobial bacteriocins, which attack only a narrow range of target bacteria. However, antimicrobials with broader activity may be advantageous. Here we identify an antimicrobial called epifadin, which is produced by nasal Staphylococcus epidermidis IVK83. It has an unprecedented architecture consisting of a non-ribosomally synthesized peptide, a polyketide component and a terminal modified amino acid moiety. Epifadin combines a wide antimicrobial target spectrum with a short life span of only a few hours. It is highly unstable under in vivo-like conditions, potentially as a means to limit collateral damage of bacterial mutualists. However, Staphylococcus aureus is eliminated by epifadin-producing S. epidermidis during co-cultivation in vitro and in vivo, indicating that epifadin-producing commensals could help prevent nasal S. aureus carriage. These insights into a microbiome-derived, previously unknown antimicrobial compound class suggest that limiting the half-life of an antimicrobial may help to balance its beneficial and detrimental activities.

Antimicrobial resistance in multistate outbreaks of nontyphoidal Salmonella infections linked to animal contact-United States, 2015-2018.

Animal contact is an established risk factor for nontyphoidal Salmonella infections and outbreaks. During 2015-2018, the U.S. Centers for Disease Control and Prevention (CDC) and other U.S. public health laboratories began implementing whole-genome sequencing (WGS) of Salmonella isolates. WGS was used to supplement the traditional methods of pulsed-field gel electrophoresis for isolate subtyping, outbreak detection, and antimicrobial susceptibility testing (AST) for the detection of resistance. We characterized the epidemiology and antimicrobial resistance (AMR) of multistate salmonellosis outbreaks linked to animal contact during this time period. An isolate was considered resistant if AST yielded a resistant (or intermediate, for ciprofloxacin) interpretation to any antimicrobial tested by the CDC or if WGS showed a resistance determinant in its genome for one of these agents. We identified 31 outbreaks linked to contact with poultry (n = 23), reptiles (n = 6), dairy calves (n = 1), and guinea pigs (n = 1). Of the 26 outbreaks with resistance data available, we identified antimicrobial resistance in at least one isolate from 20 outbreaks (77%). Of 1,309 isolates with resistance information, 247 (19%) were resistant to ≥1 antimicrobial, and 134 (10%) were multidrug-resistant to antimicrobials from ≥3 antimicrobial classes. The use of resistance data predicted from WGS increased the number of isolates with resistance information available fivefold compared with AST, and 28 of 43 total resistance patterns were identified exclusively by WGS; concordance was high (>99%) for resistance determined by AST and WGS. The use of predicted resistance from WGS enhanced the characterization of the resistance profiles of outbreaks linked to animal contact by providing resistance information for more isolates.

Multi-institutional retrospective study investigating blood culture protocols and test positivity in 701 dogs.

(i) To determine the influence of specimen collection protocol (timing and specimen quantity), primary disease process, and pre-existing antimicrobial or immunosuppressive therapy on blood culture (BC) positivity and (ii) To determine agreement between urine culture and BC results. 701 client-owned dogs. Multi-institutional retrospective study (2019-2022). Mixed-effect logistic regression was used to determine whether primary disease process, the number of BCs, or the timing of specimen collection was associated with BC positivity. Prediction plots were generated. Associations between urine culture and BC results were performed using logistic regression. Dogs with a positive urine culture were more likely to have a positive BC (OR: 4.36, 95% CI: 2.12-8.97, p = 0.003). Dogs that had three BC specimens had the greatest odds of obtaining a positive BC result (adjusted predictive value: 0.44, 95% CI: 0.21-0.70), although this was not significant. Isolates from 38.5% of dogs with a positive BC had resistance to ≥3 antimicrobial classes. The timing between specimen collection had no significant association with BC positivity. Pre-existing antibiotic or immunosuppressive therapy had no significant association with BC positivity. Dogs with a positive urine culture were more likely to have a positive BC result.

Rapid Bench to Bedside Therapeutic Bacteriophage Production.

It has been over 100years since bacteriophages (phages) were used as a human therapeutic. Since then, phage production has dramatically evolved. Current phage preparations have fewer adverse effects due to their low bacterial toxin content. As a result, therapeutic phages have become a predominant class of new antimicrobials and are being widely used for compassionate treatment of multidrug-resistant (MDR) infections. We describe herein a protocol for the production and ultrapurification of phages. By this technique, it is possible for a lab experienced with the process to produce >109 plaque-forming units (PFU) per mL of Gram-negative phages that meet FDA endotoxins limits for intravenous infusions in as little as 48hours. We provide illustrations of the process and tips on how to safely remove bacterial toxins from phage lysates. Although dependent on the phage strain, the approach described can rapidly generate and purify phages for a variety of applications.

Occurrence of Salmonella Species in Local and Commercial Chickens Slaughtered at Samaru and Sabongari Live Bird Markets, Kaduna State

Salmonellosis is a bacterial infection caused by members of the genus Salmonella. It is one of the most common and important zoonotic diseases. The route of infection from animals to humans is usually through contaminated food, water and environment. Bacteriological investigation on 303 cloacal swab samples collected from local (139) and commercial (164) chickens slaughtered at Samaru and Sabon-gari live bird markets, Kaduna State was carried out to determine the occurrence of Salmonella species. Cultural isolation and identification using conventional biochemical tests, microgen test kit™ and Polymerase Chain Reaction (PCR) amplification of invA gene of the Salmonella isolates was carried out. Isolates were subjected to antimicrobial susceptibility tests, phenotypic detection of Extended Spectrum Beta Lactamases (ESBLs) producing Salmonella isolates using the modified Clinical and Laboratory Standards Institute (CLSI) ESBL confirmatory test. The occurrence of Salmonella species based on cultural and biochemical tests was found to be 13 (4.29%), microgen kit identified 7 (53.8%) of the 13 Salmonella species while PCR based on invA gene confirmed 9 (69.2%) as the overall occurrence rate of Salmonella species. Meanwhile, the study also revealed rate of occurrence of Salmonella species in local chickens 8 (61.5%) which was higher compared to commercial chickens 1 (7.69%) with a statistical significant association (χ2 = 8.775, P = 0.003) between the occurrence of Salmonella species in local and commercial chickens. Antimicrobial susceptibility testing was carried out using panel of 12 antibiotics from 8 different antibiotic classes. Highest rate of sensitivity of the isolates to antibiotics was observed for Ofloxacin with 90%, while all the isolates (100%) were resistant to Nalidixic Acid, Cefazolin, Amoxicillin + Clavulanic Acid, Oxacillin and Penicillin. This study revealed multidrug-resistance (MDR) profile of Salmonella with a total of (25%) of Salmonella isolates being resistant to 5 antibiotics belonging to 4 different classes of antimicrobials with the highest multiple antibiotic-resistant (MAR) indices ranging from 0.58 to 0.91. All the nine (9) isolates of Salmonella tested were found to be negative for ESBLs production. Therefore, it is concluded that Salmonella species are present in local and commercial chickens slaughtered at Samaru and Sabon-gari live bird markets, Kaduna State and could pose serious public health risks to handlers and to consumers of poultry meat and its products.

Current status and trends in antimicrobial use in food animals in China, 2018–2020

Antimicrobial resistance poses a significant threat to global public health, and excessive antimicrobial use (AMU) in animals is a major contributing factor. We used national AMU data for food animals to examine the current status and trends for AMU in food animals in China from 2018–2020. In 2020, China used 32,776.30 tons of antimicrobials in food animals, amounting to 165 g of antimicrobials per ton of animal products. AMU in China increased throughout the 2018–2020 study period; however, the data still showed a consistent and notable reduction from those of 2017, coinciding with the implementation of the China National Action Plan for Combating Animal Antimicrobial Resistance. Among the antimicrobials used, tetracyclines, macrolides and β-lactams (including β-lactam inhibitors) were the most commonly used in food animals. Analysis by antimicrobial class revealed shifts in usage patterns, such as decreased tetracycline use and increased macrolide and β-lactam use. Furthermore, the use of antimicrobial growth promoters decreased sharply, from 51.78% in 2018 to 28.7% in 2020. Compared with AMU data from other countries, China used more antimicrobials, but the values were relatively lower when adjusted for population correction units. These findings highlight China's remarkable efforts in combating antimicrobial resistance and promoting antimicrobial stewardship, thus contributing significantly to global initiatives.

Effect of a dairy farmworker stewardship training program on antimicrobial drug usage in dairy cows

Antimicrobial use (AMU) is critical to preserving animal health and welfare. However, the development of antimicrobial resistance (AMR) represents a public health threat. Although most antimicrobials used on the farm require a veterinarian prescription, farmworkers make daily on-farm treatment decisions. Therefore, farmworker training is vital to promote responsible AMU. This research project aimed to evaluate the effect of farmworker antimicrobial stewardship (AMS) training on the quantity of AMU on dairy farms in Ohio and California. We hypothesized that farms receiving AMS training would have reduced AMU in dairy cattle compared with farms where training wasn't administered. We designed a quasiexperimental study with 18 conventional dairy farms enrolled in Ohio and California. Twelve farms received AMS training, and 6 farms did not. The AMS program included a 12-wk training focused on accurate identification of cows requiring antimicrobial treatment. We quantified AMU by collecting used drug containers, manually counted by researchers during farm visits. Treatment incidence (TI) was calculated using animal daily doses (ADD), and Poisson regression models were used to analyze the TI data. Disease incidence rate (DIR) in lactating cows was 2.2, 1.5, 1.0, 0.4, 0.3, 0.2, and 0.03/1,000 cow-days for mastitis, lameness, metritis, pneumonia, retained placenta, diarrheas, and other diseases (e.g., conjunctivitis, injuries), respectively. The highest TI by antimicrobial class (provided in ADD/1,000 cow-days) was cephalosporin (5.9), penicillin (5.2), tetracyclines (0.4), lincosamides (0.2), and sulfonamides (0.1). Among the trained farms using a within-treatment group analysis, no significant differences were observed in TI pre-intervention (10.9 ADD/1,000 cow-days) compared with TI postintervention (10.3 ADD/1,000 cow-days). Treatment incidence from the training group was 10.8 ADD/1,000 cow-days and although numerically lower, it was not significantly different compared with TI in the control groups at 13.9 ADD/1,000 cow-days (rate ratio = 0.77, CI = 0.25-2.38). Future research on AMS should incorporate farmworker training with social science approaches to overcome barriers and promote on-farm responsible use.