Objectives To investigate the prevalence, genomic relatedness, and resistance characteristics of carbapenemase-gene-positive Morganella spp. (CRM) across human, animal, fly, and aquatic sources. Methods A total of 163 Morganella isolates were collected from humans (n=124), animals (n=5), flies (n=21), aquatic environment (n=13) across 13 provinces or municipalities during 2018-2024. A subset of 71 representative isolates was subjected to antimicrobial susceptibility testing (AST), whole-genome sequencing and conjugation experiments. Results Among 163 isolates, 18 were carbapenemase-gene-positive: 15 carried blaNDM-1 alone, two carried blaKPC-2 alone, and one carried both genes. They were recovered from humans, flies, and hospital sewage. Five isolates carried blaPER-4; four carbapenemase-negative carriers were resistant to both ceftazidime/avibactam and aztreonam/avibactam. The aac(3)-IV gene was associated with high apramycin MICs and was most frequent in animal- and fly-derived isolates. Phylogenetic analysis showed diverse lineages, with limited low-SNP links between human and urban-river isolates. blaNDM-1 was transferred successfully from 11 of 16 donor isolates. Conclusion CRM occur across multiple One Health niches. The findings highlight environmental and non-human reservoirs as potential contributors to their dissemination and identify blaPER-4 and aac(3)-IV as resistance-associated genes requiring further study.
Introduction and Objective : Carbapenem-resistant Pseudomonas aeruginosa (CRPA) causes severe and potentially life-threatening infections in hospitalized patients with mortality rates exceeding 40%. To detect intestinal CRPA carriage in humans for surveillance purposes or to prevent spread and outbreaks in hospitals, a highly-sensitive culture method is needed. We aimed to develop such a highly-sensitive method, that would be feasible in laboratories with limited resources as well. Methods : This study used seven well-defined CRPA strains belonging to high-risk clones, including six strains with a carbapenemase gene and one OprD-deficient strain. We applied a stepwise approach that included four enrichment broths and eight Pseudomonas aeruginosa-selective culture media. Spiking experiments were performed to further evaluate the combination of the most sensitive enrichment broths and selective agar plates using human stools. Results : The two most sensitive enrichment broths were tryptic soy broth (TSB) with 2 mg/L vancomycin and TSB with 2 mg/L vancomycin and 2 mg/L imipenem and the most sensitive selective agar plates were Pseudomonas isolation agar (PIA; Becton Dickinson), PIA (Sigma-Aldrich), and M-PA-C (Becton Dickinson). After the spiking experiment, the best method for detecting CRPA based on sensitivity and selectivity was the combination of TSB with 2 mg/L vancomycin and 2 mg/L imipenem as an enrichment broth for overnight incubation, followed by subculturing the broth on M-PA-C agar plate. Conclusion : We have thus developed a highly-sensitive selective method to detect intestinal CRPA carriage in humans that can be applied in limited-resource laboratories. This may contribute to overall efforts to control CRPA.
BACKGROUND:Nontuberculous mycobacterial pulmonary disease (NTM-PD) and multidrug-resistant pulmonary tuberculosis (MDR-PTB) share overlapping clinical and radiological features, leading to frequent misdiagnosis and inappropriate treatment. Simple, low-cost risk stratification tools are needed, particularly for nursing staff in resource-limited settings. This study developed and evaluated a Nutritional-Inflammatory Composite Score (NICS) for differentiating NTM-PD from MDR-PTB. METHODS:We retrospectively enrolled 500 patients with suspected MDR-PTB who underwent confirmatory microbiological testing. Final diagnoses were MDR-PTB (n=338, 67.6%) and NTM-PD (n=162, 32.4%). Three logistic regression models were compared: clinical (age, BMI, smoking, diabetes, COPD, bronchiectasis), laboratory (CRP, albumin, ferritin, lymphocytes), and NICS-based (age, BMI, diabetes, COPD, bronchiectasis, and NICS). Model discrimination was assessed by area under the ROC curve (AUC). RESULTS:NICS was the strongest independent predictor of NTMPD (OR=1.14 per unit increase, 95% CI: 1.08-1.20, p<0.001). The NICS-based model achieved the highest AUC (0.66, 95% CI: 0.61-0.71), compared with the clinical model (AUC=0.57, 95% CI: 0.52-0.62) and the laboratory model (AUC=0.60, 95% CI: 0.54-0.65). Using the Youden derived optimal cutoff, sensitivity was 35.19%, specificity 73.96%, PPV 39.31%, and NPV 70.42% (overall correct classification 61.40%). CONCLUSION:NICS improves NTMPD versus MDRPTB discrimination modestly but significantly (ΔAUC = 0.09 vs. clinical model). The nomogram represents a preliminary research instrument for risk estimation; however, the low sensitivity at the optimal threshold precludes its use as a diagnostic tool, limiting its role to hypothesis generation pending prospective validation. Prospective usability testing and external validation remain necessary.
Objectives The numbers of infections caused by carbapenem-resistant Acinetobacter baumannii (CRAB) are increasing globally and present a significant burden on healthcare systems. This study describes the CRAB isolates received at the Swiss National Reference Centre for Emerging Antibiotic Resistance (NARA) over a 3-year period, from January 2022 to December 2025, and aimed to characterize the prevalence and mechanisms of FDC resistance. Methods Two-hundred and thirty-four non-duplicate CRAB isolates were submitted to NARA over the study period from hospitals and laboratories across Switzerland. Susceptibility testing was performed by disk diffusion and broth microdilution, according to EUCAST methodology. Whole-genome sequencing was performed on 11 isolates. ADC alleles were cloned into vector pVRL1 and transformed into Escherichia coli Top10. Results All isolates exhibited resistance to the carbapenems, and most were resistant to cephalosporins. Most isolates harboured an acquired class D carbapenemase, most frequently OXA-23 (181/234; 77.4%). One quarter of isolates were resistant to cefiderocol (FDC), exhibiting MICs ranging from 4->32 mg/L. Whole genome sequencing analyses, performed on 11 FDC-resistant isolates, identified that FDC resistance was due a combination of mechanisms including NDM and PER-production, mutations within the iron transporters, piuA and pirA, and the overexpression of ADC variants. Conclusions This study showed that OXA-23 was the dominant mechanism of carbapenem-resistance in CRAB in Switzerland. Almost one quarter of CRAB isolates were resistant to “last resort” antimicrobial, FDC. The mechanisms of FDC resistance identified in this study emphasise that resistance to this antimicrobial is often complex and multifactorial, requiring high-resolution methods, including WGS, to identify.
Objectives While randomized controlled trials demonstrate omadacycline's efficacy and safety in community-acquired pneumonia (CAP), real-world evidence is sparse. This study evaluated clinical effectiveness, safety, and the factors influencing clinical success and 30-day mortality for CAP patients treated with omadacycline in real-world conditions. Methods We performed a study of CAP patients treated with omadacycline. The outcomes included clinical efficacy, 30-day mortality, microbial eradication, and adverse events. Multivariate logistic regression identified risk factors for clinical failure, with model performance assessed by Receiver Operating Characteristic (ROC) curves. Kaplan-Meier survival analysis and Cox proportional hazards regression were used to analyze prognostic factors. Results Among 150 patients, the clinical success rate was 86.0%. Multivariate analysis identified respiratory failure (OR 10.817, 95% CI 1.800-64.990) and higher Pneumonia Severity Index (PSI) score (OR 1.028, 95% CI 1.006-1.051) as independent risk factors for clinical failure. The ROC curve showed the area under the curve (AUC) value of the prediction model was 0.946 (95% CI: 0.904-0.989). The 30-day mortality rate was 6.7%. Kaplan-Meier analysis showed poorer survival for patients with Sequential Organ Failure Assessment (SOFA) score ≥2, PSI >130, age >80 years, ICU admission, or early clinical failure (P < 0.05). Cox regression confirmed early clinical failure (HR 0.031, 95% CI 0.001-0.710) and higher SOFA score (HR 1.500, 95% CI 1.076-2.091) independently predicted 30-day mortality. Conclusion Omadacycline was effective and safe for CAP treatment in real-world practice, including elderly and comorbid patients.
Background Serratia nevei is a newly classified and opportunistic bacterial species belonging to the Serratia marcescens complex (SMC). Genomic data from this species is highly relevant for public health and epidemiological tracking. Objective To report the first identification and genomic characterization of extended-spectrum β-lactamase (CTX-M-15)-producing S. nevei sequence type (ST) ST625 lineage infecting a vulnerable loggerhead sea turtle. Methods Strain BP02 was recovered from the coelomic cavity of a loggerhead sea turtle (Caretta caretta) admitted to a rehabilitation center in southeastern Brazil. MALDI-TOF MS was initially used for species identification and was further confirmed by whole-genome sequencing on the Illumina HiSeq platform, followed by ANI, dDDH, multilocus sequence typing, resistome, plasmidome, virulome, and SNP-based phylogenomic analyses. Results Strain BP02 exhibited a multidrug-resistant profile, including resistance to third- and fourth-generation cephalosporins. Genomic analyses identified BP02 as S. nevei ST625 carrying blaCTX-M-15 within the ISEcp1-blaCTX-M-15-wbuC-ΔTn2 genetic environment, in addition to multiple AMR determinants and the IncC plasmid replicon. Phylogenomic analysis demonstrated close relatedness between BP02 and human clinical ST625 strains, previously reported in São Paulo, Brazil, including a urine-derived strain isolated in 2019, differing by only 27 SNPs. Notably, all publicly available ST625 genomes were associated with human clinical sources and displayed multidrug resistance genotypes. Conclusion This study expands the current knowledge regarding the ecology and genomic features of S. nevei, demonstrating the emergence of a human multidrug-resistant clone in marine wildlife. Our findings reinforce the importance of monitoring clinically relevant SMC members across distinct ecological niches within a One Health perspective.
Background : Therapeutic drug monitoring (TDM) of voriconazole is recommended to optimize treatment outcomes and minimize toxicity, owing to its nonlinear pharmacokinetics and substantial interindividual variability. However, data on clinicians’ awareness, attitudes, and perceived barriers remain limited. This study assessed these domains among physicians managing invasive fungal infections in Kuwait. Methods : A cross-sectional survey was conducted among intensivists, hematology/oncology and solid organ transplant physicians, infectious disease specialists, pulmonologists, and clinical microbiologists across 10 public hospitals. A validated self-administered questionnaire was used. Descriptive and nonparametric analyses were performed. Results : Of 206 invited physicians, 115 responded (55.8%), and 106 were eligible for analysis. Median (IQR) awareness was 57.1% (57.1), with 53.8% scoring <60%, indicating suboptimal knowledge. Higher awareness was associated with age >40 years (p = 0.034), consultant/senior specialist status (p = 0.038), and clinical microbiology practice (p = 0.002). Median (IQR) attitude score was 4.0 (1.0); 70.8% demonstrated positive attitudes, particularly those aged >40 years (p = 0.021) and with >10 years’ experience (p = 0.007). Median (IQR) barrier score was 4.0 (1.0), reflecting substantial implementation challenges. Common barriers included logistical coordination (67.9%), limited understanding of monitoring protocols (66.0%), and absence of clear local or national guidelines (65.1%). Barriers were more pronounced in tertiary hospitals (p = 0.018) and among physicians managing antifungal prophylaxis (p < 0.001). Conclusions : Despite generally positive attitudes, physicians in Kuwait demonstrated limited awareness and reported significant implementation barriers. Targeted education improved logistical support, and development of national guidelines are needed to enhance TDM uptake and optimize antifungal therapy.
Introduction Inappropriate antimicrobial use is a primary driver of antimicrobial resistance. This study examines outpatient antimicrobial prescribing patterns and their associated factors in Chinese private hospitals from January 2022 to April 2025. Methods We analyzed antimicrobial prescriptions from seven private hospitals in southwest China, classifying them as appropriate or inappropriate. Chi-square tests and generalized estimating equations were applied to identify factors associated with inappropriate prescribing. Results Of 147,415 antimicrobial prescriptions, respiratory (44.4%) and genitourinary disorders (39.0%) were the leading indications, while cephalosporins (33.2%) and nitroimidazoles (23.1%) were the most commonly prescribed antimicrobial classes. The overall inappropriate prescribing rate was 63.6%, with the highest rates for genitourinary (69.6%) and respiratory (61.1%) disorders. Aminoglycosides (99.5%) and lincosamides (85.0%) showed the highest inappropriateness rates. Female patients (OR=1.181, P<0.001) and those receiving injectable therapy (OR=1.396, P<0.001) had higher odds of inappropriate prescribing. Male physicians with lower education (OR=2.971, P<0.001) had higher odds. Among older (≥35 years) and more experienced (≥10 work years) physicians, technical secondary school education conferred the highest risk (OR=3.310 and 4.810, respectively, P<0.001). Attending and chief physicians shifted from protective to risk factors with increasing work experience, while associate chief physicians showed a markedly elevated risk (OR=2.770, P<0.001). Conclusions Antimicrobial stewardship efforts should prioritize genitourinary infections, with particular attention to injectable therapies and female patients. Interventions should target male physicians with higher professional titles or lower education, especially those with more experience. This necessitates enhanced regulatory oversight and tailored training programs that address the specific needs of private hospitals. Clinical registration Not applicable.
OBJECTIVES:This study investigated the in vitro activity of cefiderocol and comparator antibiotics against Gram-negative bacterial isolates with highly resistant phenotypes collected in the SENTRY Antimicrobial Surveillance Program. METHODS:Between 2020 and 2024, consecutive Gram-negative bacterial isolates were collected from hospitalized patients in the USA and Europe, Turkey and Israel. Minimum inhibitory concentrations (MICs) were determined by broth microdilution method according to Clinical and Laboratory Standards Institute (CLSI) guidelines. Susceptibility was interpreted, as applicable, by CLSI M100 (2026), European Committee on Antimicrobial Susceptibility Testing (EUCAST) (2026), and US Food and Drug Administration (FDA 2026) criteria. RESULTS:Cefiderocol was the only antibiotic that inhibited >90% of carbapenem-non-susceptible isolates by CLSI breakpoints (95.5% of 1229 Enterobacterales, 98.8% of 2807 Pseudomonas aeruginosa, 93.7% of 2254 Acinetobacter baumannii-calcoaceticus species complex, and 99.3% of 2341 Stenotrophomonas maltophilia), and susceptibilities to cefiderocol were >90% across various infection sites. Against multidrug-resistant (MDR) Enterobacterales (N = 10 606) and P. aeruginosa (N = 1817), cefiderocol susceptibility rates were 99.1% and 98.1%, respectively. Susceptibilities to comparator antibiotics ranged between 73.2% (ceftolozane-tazobactam) and 99.8% (aztreonam-avibactam) for MDR Enterobacterales, and between 18.3% (meropenem) and 77.5% (imipenem-relebactam) for MDR P. aeruginosa. 97.4% of 459 difficult-to-treat resistant P. aeruginosa were susceptible to cefiderocol. Additionally, cefiderocol displayed low MIC50/90 values against Burkholderia cepacia species complex and Achromobacter spp. (0.06/0.5 mg/L and 0.03/0.25 mg/L, respectively). CONCLUSIONS:Cefiderocol showed potent in vitro activity against contemporary isolates of Gram-negative bacteria displaying challenging resistance phenotypes.
INTRODUCTION:This study evaluated the clinical outcomes of invasive pulmonary aspergillosis (IPA) treated with voriconazole (VRCZ), posaconazole (PSCZ), or isavuconazole (ISCZ) using a large-scale real-world database. MATERIALS AND METHODS:A retrospective study using the TriNetX database (2010-2025) identified patients with IPA initiated on VRCZ, PSCZ, or ISCZ. Background factors were adjusted using Propensity Score Matching (PSM). The primary endpoint was 6-week all-cause mortality. RESULTS:Of 8,746 patients identified, 3,603 met selection criteria (VRCZ: 2,836; PSCZ/ISCZ: 767). PSM identified 738 matched pairs of balanced covariates. The 6-week mortality was 18.6% for VRCZ and 16.4% for PSCZ/ISCZ (OR 1.16; 95% CI 0.89-1.52; p=0.273). No significant differences were observed in the primary, subgroup, or sensitivity analyses. Notably, the PSCZ/ISCZ group initially included more severe cases and patients with renal impairment. CONCLUSION:No significant differences in all-cause mortality were observed among the three drugs. Despite the higher baseline risk in the PSCZ and ISCZ groups, the outcomes were comparable to those in the VRCZ group, suggesting that these agents are effective alternatives in high-risk real-world settings. PSCZ and ISCZ are valuable options in personalized medicine. Therefore, further prospective studies are warranted.
OBJECTIVES:Based on surveillance data from Chinese livestock and poultry farms between 2011 and 2021, we analysed the antimicrobial resistance and transmission characteristics of diarrheagenic Escherichia coli (DEC) and non-diarrheagenic strains. METHODS:Phenotypic antibiotic resistance testing, antibiotic resistance gene screening, plasmid typing, and multilocus sequence typing were performed using 1114 identified isolates, and a phylogenetic tree was constructed to assess genetic relationships. RESULTS:DEC accounted for 2.7% of all strains, with enterotoxin-producing E. coli being the predominant subtype. DEC strains exhibited significantly higher rates of antimicrobial resistance phenotypes, resistance genes, and plasmid carriage than non-DEC strains (P < 0.001), primarily attributable to the host source. Pig-derived DEC strains exhibited significantly higher resistance rates to apramycin, tobramycin, kanamycin, and colistin, as compared with non-DEC strains (P < 0.01), as well as increased carriage rates of mcr-1.1, blaOXA-1, and aac(3)-IVa and a higher prevalence of IncI and IncHI2. Multilocus sequence typing analysis indicated that DEC strains predominantly comprised ST10 and ST29. The phylogenetic tree revealed that strains clustered according to pathogenicity types; the enterotoxin-producing E. coli branch carried blaCTX-M-55, consistent with the ceftiofur-resistant phenotype, which was primarily localized to IncF family fusion plasmids. CONCLUSIONS:DEC showed a low prevalence in healthy farmed animals, with the host source having a greater impact on the transmission of antibiotic resistance than the pathogenic type itself. The present findings provide a scientific basis for the rational use of antibiotics and monitoring of antibiotic resistance risks in the Livestock Farming industry.
OBJECTIVE:To analyse clinical characteristics of carbapenemase-producing Enterobacterales (CPE) infection and explore factors associated with their short-term (30-day) and long-term (90-day) prognostic outcomes. METHODS:A retrospective cohort study enrolled 192 nonduplicate patients with microbiologically confirmed CRE infection between January 2023 and June 2025 at a secondary-care hospital. All isolates underwent carbapenemase detection. Demographic data, clinical features, laboratory findings, treatment interventions, and 30-day/90-day prognostic outcomes were collected. Kaplan-Meier survival curves were generated, and the Log-rank tests were used for intergroup survival comparison. Univariate and multivariate Cox proportional hazards regression models were employed to identify independent prognostic factors for 30-day and 90-day mortality. RESULTS:All CRE isolates were confirmed as carbapenemase producers, with significant antimicrobial susceptibility differences. The 30-day and 90-day all-cause mortality rates were 23.43% (95% CI: 17.39%-29.48%) and 27.60% (95% CI: 21.22%-33.98%), respectively. Multivariate analyses revealed independent associations with 30-day mortality, including septic shock/sepsis (aHR = 2.528, 95% CI: 1.126-5.678), fasting plasma glucose (aHR = 1.113, 95% CI: 1.034-1.197), and hospital-onset infection (aHR = 2.246, 95% CI: 1.145-4.406). For 90-day mortality, additional factors included albumin infusion (aHR = 3.081, 95% CI: 1.350-7.096) and MBL type (aHR = 2.410, 95% CI: 1.301-4.465). Appropriate antimicrobial therapy was significantly associated with reduced 30-day (aHR = 0.424, 95% CI: 0.219-0.823) and 90-day (aHR = 0.346, 95% CI: 0.182-0.659) mortality risk. CONCLUSIONS:Secondary-care hospitals present high prevalence of CPE, accompanied by a substantial mortality burden among infected patients. This study provides evidence-based guidance for optimising CPE management.
OBJECTIVE:Acinetobacter baumannii is an opportunistic pathogen infecting immunocompromised patients, including the pediatric population. Treatment options for severe infections are challenged by the dissemination of carbapenem-resistant A. baumannii (CRAB), mostly belonging to 11 international clones (ICs 1-11). We characterized gene contents, genetic elements, and phylogenetic relationships of CRAB isolates. METHODS:Unlike neighbouring countries, the characterization of CRAB from Libya is rare. In this study, 38 CRAB isolates collected during 2020-2021 from patients treated in the Tripoli University Hospital (TUH) were characterized by whole-genome sequencing for their antibiotic resistance genes content, their genetic elements, and their phylogenetic relationship to international isolates. RESULTS:The 38 isolates belonged to IC1, IC2, IC6, IC7, and IC11, the latter being the most frequently identified. All isolates harboured a blaOXA-23 gene, except IC6 isolates, which carried a plasmid-located blaOXA-72. The blaNDM-1 gene occurred only in IC1 isolates. The phylogenetic analysis including publicly available genomes evidenced a clustering according to the continent of origin. Isolates from TUH were phylogenetically close to isolates from North Africa or the Middle East. Most of the CRAB (22 of 38, 58%) came from children, eight of whom died (36%). Circulation among adult and paediatric wards of the same clone was observed. CONCLUSIONS:At the TUH, improvement of hygiene measures is needed to lower the burden of CRAB. At the international level, surveillance of this pathogen remains crucial to prevent its further spread from endemic regions or from conflict zones where injuries are more frequent and hygiene conditions are more precarious.
OBJECTIVES:To develop and evaluate a rapid phenotypic method for detecting aztreonam-avibactam (AZA) resistance-associated phenotypes in Pseudomonas aeruginosa. METHODS:Test isolates were incubated in medium containing fixed concentrations of AZA (aztreonam 20 µg/mL and avibactam 4 µg/mL). Resazurin was used as a redox indicator to monitor bacterial metabolic activity, with colour change from blue to purple/pink indicating growth. The assay was evaluated using 103 clinical P. aeruginosa isolates with different AZA MIC profiles, using broth microdilution as the reference method. Isolates were classified according to the EUCAST tentative ECOFF-based epidemiological framework. Interassay reproducibility was assessed using independent assay runs. RESULTS:The rapid NP test showed 100% agreement with the tentative ECOFF-based wild-type/nonwild-type classification derived from the reference broth microdilution method across all 103 clinical isolates. Consistent wild-type/nonwild-type classifications were obtained across independent assay runs, supporting the interassay reproducibility of the method. The total turnaround time was 8 h. CONCLUSIONS:This method is simple, rapid, and reliable, providing an intuitive approach for detecting AZA resistance-associated phenotypes in P. aeruginosa, with potential utility as a targeted screening approach in clinical microbiology laboratories.
Carbapenemase-producing Acinetobacter are multidrug-resistant pathogens mainly associated with healthcare infections but are increasingly detected in wildlife exposed to human environments. In this study, we report and characterize a carbapenem-resistant Acinetobacter bereziniae strain related to fatal pneumonia and stomatitis in a rescued Burmese python (Python bivittatus) in São Paulo, Brazil. Whole genome sequencing revealed plasmid-borne blaNDM-1 and blaOXA-58 genes, and phylogenomic analysis clustered the strain with human clinical isolates. These findings highlight the threat of carbapenemase-producing bacteria to wildlife and reinforce the need for a One Health surveillance approach.
BACKGROUND:Considering the increasing reports of antimicrobial resistance (AMR) in wildlife, highlighting its complexity, importance, and spread. We investigated the prevalence of extended-spectrum beta-lactamase (ESBL)-producing Enterobacterales in the hooded crow. METHODS:Faecal samples were collected from 52 rural and 212 urban wild crows in Hungary, caught using ladder traps, and tested for ESBL presence. Bacterial species were identified using MALDI-TOF. Antibiotic susceptibility was tested using the disc diffusion method, and ESBL producers were detected based on double-disc synergy. ESBL-encoding genes were identified using PCR, and WGS was performed on isolated ESBL-producing E. coli (197/221 isolated ESBLs). RESULTS:Four of the sampled rural Hooded Crows and 130 urban ones (7.7% vs. 61%, chi-square p < 0.0001) yielded ESBL producers with the overwhelming dominance of E. coli. The blaCTX-M-1 group was predominant in both groups. In addition to CTX-M genes, genes encoding resistance to other antibiotic classes, such as APHs, sul genes, tet genes, etc., various virulence factors, and several incompatible plasmids were also detected. Most isolates belonged to the B1 and A phylogenetic groups. Overall, 22 sequence types (STs) and 33 distinct cgSTs were defined. The most prevalent ST was ST58, followed by ST10, S38, ST155, ST442, and more. CONCLUSIONS:The much higher carrier frequency among urban crows points to the role of anthropogenic sources in the emergence of ESBL producers. Hooded Crows, due to their increasing presence in cities and proximity to humans, likely facilitate the dissemination of ESBL producers between the environment and humans.
OBJECTIVES:Carbapenemase-producing Enterobacterales have disseminated globally, largely via highly transmissible plasmids. Their emergence in companion animals is of particular concern, indicating that clinically important carbapenem-resistance determinants have spread beyond healthcare settings. This study characterized a multidrug-resistant Escherichia coli isolate from a healthy dog in South Korea. METHODS:Antimicrobial susceptibility was determined by standardized reference methods. Hybrid whole-genome assembly resolved chromosomal and plasmid architectures, and plasmid transferability was assessed by conjugation assays. Comparative genomic analysis based on nucleotide identity and alignment coverage evaluated relatedness to publicly available blaKPC-carrying IncX3 plasmids. RESULTS:The E. coli ST7854 isolate was resistant to carbapenems (imipenem MIC = 8 µg/mL), third-generation cephalosporins, fluoroquinolones, tetracycline, gentamicin, phenicols, and trimethoprim-sulfamethoxazole, but susceptible to amikacin and colistin. Assembly resolved a 4.77 Mb circular chromosome and seven plasmids. The ESBL gene blaCTX-M-27 was chromosomally integrated, whereas carbapenem resistance was conferred by blaKPC-2 on a 54,805 bp IncX3 plasmid. This IncX3-blaKPC-2 plasmid was transferred to E. coli J53 at a frequency of 5.91 × 10⁻⁴, whereas the large IncFIB multidrug resistance plasmid was not co-transferred. Comparative analysis revealed extensive structural similarity with Korean clinical IncX3 plasmids, whereas most representative international plasmids shared only the conserved IncX3 backbone. CONCLUSIONS:A commensal E. coli ST7854 isolate from a healthy companion dog carried a conjugative IncX3-blaKPC-2 plasmid and chromosomally integrated blaCTX-M-27. Similarity to Korean clinical plasmids suggests potential human-animal dissemination, and this asymptomatic carriage of mobile carbapenem-resistance determinants supports continued genomic surveillance of antimicrobial resistance in companion animals within a One Health framework.
OBJECTIVE:Antimicrobial resistance in pathogens causing bovine respiratory disease (BRD) is promoted by the prophylactic use of antimicrobials in calves. However, the impact of discontinuing their use under field conditions remains unclear. This study evaluated changes in antimicrobial susceptibility of Mannheimia haemolytica and Pasteurella multocida following cessation of prophylactic oxytetracycline and tilmicosin on a contract-rearing farm for Holstein heifer calves in Japan. METHODS:Oxytetracycline was administered via milk replacer at 20 mg/kg/d to calves aged 6-60 d of age and discontinued in April 2022, whereas prophylactic tilmicosin (10 mg/kg, single subcutaneous injection at arrival) was discontinued in May 2023. From November 2021 to November 2023, 850 nasal and ear swab samples were collected from 583 calves with suspected BRD, yielding 492 M. haemolytica and 215 P. multocida isolates. These isolates underwent antimicrobial susceptibility testing and screening for oxytetracycline resistance genes. RESULTS:Over 1 y post-oxytetracycline withdrawal, minimum inhibitory concentration distributions for oxytetracycline indicated a significant shift towards susceptibility in both species; resistance to oxytetracycline declined from 9.2% to 0% in M. haemolytica and from 75.0% to 5.6% in P. multocida. The minimum inhibitory concentrations of florfenicol and macrolides (tilmicosin and tulathromycin) decreased with time. Most tetracycline-resistant isolates carried tet(H). After oxytetracycline discontinuation, the BRD incidence increased, and average daily gain decreased; however, both improved following the introduction of an inactivated trivalent BRD vaccine. CONCLUSIONS:Discontinuing long-term prophylactic antimicrobial administration can restore antimicrobial susceptibility in BRD pathogens and aid in preserving therapeutic antimicrobial effectiveness when implemented alongside vaccination strategies.
OBJECTIVES:Skin and mucosal viral infections caused by Herpes simplex virus types 1 and 2 (HSV-1 and HSV-2), often complicated by opportunistic bacteria such as Staphylococcus epidermidis (S. epidermidis), represent a significant clinical challenge. Increasing resistance to conventional antivirals and antibiotics underscores the urgent need for alternative therapies. Here, Ranalexin-1G, an amphibian-derived antimicrobial peptide from Rana grylio, was investigated for its antiviral and antibacterial properties. METHODS:Ranalexin-1G was evaluated for its antiviral activity by plaque reduction assay and qPCR. Antibacterial activity against S. epidermidis was assessed by measuring growth inhibition and minimum inhibitory concentration values for both reference and clinical strains. In addition, an in vitro coinfection model (HSV-1 + S. epidermidis) in HaCaT keratinocytes was used to examine the peptide dual functionality. RESULTS:Ranalexin-1G exhibits a dual activity: It demonstrates potent antiviral effects against HSV-1, HSV-2, and an acyclovir-resistant HSV-1 strain, with half-maximal inhibitory concentration (IC50) values ranging from 3 to 10 µM. Additionally, Ranalexin-1G shows strong antibacterial activity, achieving 90% inhibition of S. epidermidis growth, with minimum inhibitory concentration values of 3.125 and 6.25 µM for the reference and clinical strains, respectively. Consistent with these findings, in an in vitro coinfection model of HSV-1 and S. epidermidis in HaCaT cells, Ranalexin-1G significantly reduced bacterial invasion. CONCLUSIONS:Overall, Ranalexin-1G emerges as a promising candidate for the treatment of polymicrobial skin infections, particularly those involving viral-bacterial coinfections, due to its balanced efficacy and low cytotoxicity profile.
