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Antibiotics
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Detection of Bacteria and Antibiotics Surveillance in Livestock
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Detection of Bacteria and Antibiotics Surveillance in Livestock

A special issue of Antibiotics (ISSN 2079-6382). This special issue belongs to the section "Antibiotics in Animal Health".

Deadline for manuscript submissions: closed (30 May 2025) | Viewed by 13237

Special Issue Editor

Dr. Danijela Horvatek Tomić

E-Mail Website
Guest Editor
Department of Poultry Diseases with Clinic, Faculty of Veterinary Medicine, University of Zagreb, Heinzelova 55, 10000 Zagreb, Croatia
Interests: bacterial zoonoses; poultry diseases; antibiotic resistance; exotic animals

Special Issue Information

Dear Colleagues,

Because the borders between countries are wide open and there is a free movement of goods, people and animals, the spread of infectious diseases is significantly facilitated. Viral and bacterial infectious diseases represent one of the main causes of death worldwide, in both human and veterinary medicine. However, it is also necessary to mention their negative impact on productivity and the economy. Therefore, it is necessary to detect pathogenic bacteria in different livestock by employing the most suitable methods, in regard to the sample type, the timescale of obtaining results, and costs. Antimicrobial resistance (AMR) is closely related to the pathogenic bacteria present in livestock.  It is therefore necessary to monitor data on the incidence of AMR throughout the entire food chain, from farm to table, using methods that enable an easier comparison between results and their further analysis.

Dr. Danijela Horvatek Tomić
Guest Editor

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Keywords

  • livestock
  • bacteria
  • pathogens
  • antibiotic resistance
  • antibiotic surveillance
  • zoonoses

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Published Papers (11 papers)

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Research

13 pages, 255 KiB  
Communication
Aerobic Uterine Pathogens in Dairy Cattle: Surveillance and Antimicrobial Resistance Profiles in Postpartum Endometritis
by Ionica Iancu, Sebastian Alexandru Popa, Janos Degi, Alexandru Gligor, Ionela Popa, Vlad Iorgoni, Paula Nistor, Kálmán Imre, Ileana Nichita and Viorel Herman
Antibiotics 2025, 14(7), 650; https://doi.org/10.3390/antibiotics14070650 - 26 Jun 2025
Viewed by 325
Abstract
Bovine uterine infections remain a widespread challenge in dairy production systems, contributing to reduced fertility and overall herd performance. Background/Objectives: Postpartum uterine infections significantly affect dairy cattle fertility and productivity. This study aimed to identify aerobic bacterial pathogens associated with clinical endometritis [...] Read more.
Bovine uterine infections remain a widespread challenge in dairy production systems, contributing to reduced fertility and overall herd performance. Background/Objectives: Postpartum uterine infections significantly affect dairy cattle fertility and productivity. This study aimed to identify aerobic bacterial pathogens associated with clinical endometritis in Romanian dairy cows and evaluate their antimicrobial resistance profiles. Methods: Uterine swab samples (n = 348) were collected from clinically affected cows across multiple farms. Bacteria were isolated and identified using conventional culture methods and MALDI-TOF MS. Antimicrobial susceptibility testing was performed using the VITEK® 2 system with GN 96 and GP 79 cards. Statistical analysis was conducted using the chi-square (χ2) test. Results: A total of 387 bacterial isolates were recovered, with over half of the samples showing mixed bacterial contamination. Escherichia coli was the most frequently identified pathogen (44.9%), followed by Staphylococcus spp. (17.3%) and Klebsiella spp. (14.5%). Gram-negative isolates showed high resistance to tetracycline and ampicillin, while retaining susceptibility to imipenem and polymyxin B. Among Gram-positive isolates, Streptococcus spp. were highly susceptible to β-lactams, while Staphylococcus spp. showed moderate resistance to penicillin and macrolides. Conclusions: This study highlights the prevalence of key aerobic pathogens and their resistance profiles in Romanian dairy herds. These findings support the need for targeted diagnostics and rational antimicrobial use to improve uterine health and therapeutic outcomes in dairy cattle. Full article
(This article belongs to the Special Issue Detection of Bacteria and Antibiotics Surveillance in Livestock)
19 pages, 3856 KiB  
Article
Antimicrobial Susceptibility Profiles of Escherichia coli Isolates from Clinical Cases of Geese in Hungary Between 2022 and 2023
by Ádám Kerek, Ábel Szabó and Ákos Jerzsele
Antibiotics 2025, 14(5), 450; https://doi.org/10.3390/antibiotics14050450 - 29 Apr 2025
Viewed by 548
Abstract
Background: Antimicrobial resistance (AMR) poses an increasing threat to animal health and food safety. In the poultry sector, particularly in waterfowl farming, the widespread use of antibiotics may contribute to the dissemination of resistant Escherichia coli strains. This study aims to map the [...] Read more.
Background: Antimicrobial resistance (AMR) poses an increasing threat to animal health and food safety. In the poultry sector, particularly in waterfowl farming, the widespread use of antibiotics may contribute to the dissemination of resistant Escherichia coli strains. This study aims to map the antibiotic resistance profiles of E. coli isolates from geese in Hungary, determine the prevalence of multidrug-resistant (MDR) and extensively drug-resistant (XDR) strains, and analyze resistance patterns and co-resistance relationships. Methods: E. coli isolates from clinical cases between 2022 and 2023 were examined using minimum inhibitory concentration (MIC) determination. Susceptibility results were evaluated based on the Clinical Laboratory Standard Institute (CLSI) breakpoints. Cluster analysis and principal component analysis (PCA) were applied to identify resistance patterns. Co-resistance relationships were examined through network analysis, while Monte Carlo simulations were used to estimate the expected prevalence of MDR strains. Results: Among the examined isolates, neomycin resistance was particularly high (86.8%), while florfenicol (73.6%) and amoxicillin (65.9%) resistance levels were also significant. The prevalence of MDR strains was 86.8%, and XDR strains accounted for 38.5%. Co-resistance analysis revealed a strong correlation between neomycin and spectinomycin resistance, as well as amoxicillin and doxycycline resistance. Monte Carlo simulations estimated that the expected range of MDR strain prevalence could vary between 80.2% and 92.3%. Conclusions: The high prevalence of MDR and XDR strains highlights the urgent need to reassess antibiotic usage strategies in goose farming. These findings underscore the importance of targeted antibiotic use, continuous microbiological surveillance, and the exploration of alternative therapeutic approaches to mitigate AMR. Full article
(This article belongs to the Special Issue Detection of Bacteria and Antibiotics Surveillance in Livestock)
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18 pages, 2417 KiB  
Article
Antimicrobial Susceptibility Profiles of Escherichia coli Isolates from Clinical Cases of Turkeys in Hungary (2022–2023)
by Ákos Jerzsele, Ábel Szabó, Franciska Barnácz, Bence Csirmaz, László Kovács and Ádám Kerek
Antibiotics 2025, 14(4), 338; https://doi.org/10.3390/antibiotics14040338 - 25 Mar 2025
Viewed by 562
Abstract
Background: The global spread of antimicrobial resistance is one of the defining challenges of our time. Preserving the efficacy of antibiotics is a shared responsibility, which includes conducting regular surveillance studies. The poultry industry, which produces the highest quantity of animal-derived protein in [...] Read more.
Background: The global spread of antimicrobial resistance is one of the defining challenges of our time. Preserving the efficacy of antibiotics is a shared responsibility, which includes conducting regular surveillance studies. The poultry industry, which produces the highest quantity of animal-derived protein in the shortest time, faces significant challenges from Escherichia coli, a bacterium frequently responsible for clinical disease. Methods: This study aimed to assess the susceptibility of E. coli isolates collected from clinical cases in turkeys across Hungary to antibiotics of veterinary and public health importance using minimum inhibitory concentration (MIC) determination. Results: Over the course of one year, we analyzed a total of 70 clinical isolates. Most isolates (64.3%) were resistant to amoxicillin, and the observed 25.7% resistance to amoxicillin–clavulanic acid suggests that the majority of strains are beta-lactamase producers. The highest resistance level was observed against neomycin (74.3%). Resistance to critically important antibiotics, including enrofloxacin (28.6%), ceftriaxone (8.6%), and colistin (7.1%) raises significant public health concerns. When comparing our results with human hospital resistance data from Hungary, most findings showed comparable values, with the exception of neomycin, which exhibited markedly higher resistance in the isolates from poultry. Conclusions: Our findings underscore the necessity of regular surveillance studies, which should be periodically repeated in the future to observe temporal trends. These results should also be linked to antibiotic usage patterns, and the genetic background of multidrug-resistant strains should be further examined using next-generation sequencing techniques. This study provides critical insights into the current antimicrobial resistance landscape in the Hungarian poultry industry and highlights the urgent need for targeted interventions to prevent the dissemination of resistant strains to humans. The findings contribute valuable data for developing future AMR management strategies in veterinary and public health contexts. Full article
(This article belongs to the Special Issue Detection of Bacteria and Antibiotics Surveillance in Livestock)
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19 pages, 3093 KiB  
Article
Antimicrobial Susceptibility Profiles of Commensal Enterococcus spp. Isolates from Turkeys in Hungarian Poultry Farms Between 2022 and 2023
by Ádám Kerek, Ábel Szabó, Franciska Barnácz, Bence Csirmaz, László Kovács and Ákos Jerzsele
Antibiotics 2025, 14(4), 331; https://doi.org/10.3390/antibiotics14040331 - 21 Mar 2025
Viewed by 746
Abstract
Background: Antimicrobial resistance (AMR) has become a serious global challenge in the 21st century. Poultry, including turkeys, are a vital source of animal-derived protein worldwide. Commensal bacterial strains in poultry can act as reservoirs for AMR, making monitoring them crucial for both veterinary [...] Read more.
Background: Antimicrobial resistance (AMR) has become a serious global challenge in the 21st century. Poultry, including turkeys, are a vital source of animal-derived protein worldwide. Commensal bacterial strains in poultry can act as reservoirs for AMR, making monitoring them crucial for both veterinary and public health. Enterococcus species are emerging pathogens, particularly in severe nosocomial infections. Methods: This study aimed to assess the resistance profiles of commensal Enterococcus strains isolated (n = 470) from large-scale turkey flocks in Hungary. From each animal, two swab samples were collected: one from the oropharyngeal region near the tracheal entrance and one from the cloaca. The samples were subsequently processed, and the minimum inhibitory concentration (MIC) was determined following the Clinical and Laboratory Standards Institute (CLSI) guidelines. The tested antibiotics included amoxicillin, amoxicillin–clavulanic acid, imipenem, neomycin, doxycycline, florfenicol, tylosin, enrofloxacin, potentiated sulfonamide, vancomycin, ceftriaxone, spectinomycin, tiamulin, lincomycin, and colistin. The dilution range for MIC determination was set between 512 and 0.001 µg/mL. Results: Resistance to amoxicillin, a first-line treatment for Enterococcus infections, was low (11.1%). However, high resistance levels were observed for tylosin (62.6%), florfenicol (51.1%), doxycycline (48.7%), and enrofloxacin (45.5%). Notably, vancomycin resistance reached 15.5%, a finding consistent with global trends. Compared to human-derived Enterococcus data, resistance to aminopenicillins was significantly lower in turkey isolates, while neomycin resistance levels were comparable to those observed in human E. faecalis strains. Conclusions: The findings underscore the necessity of continuous surveillance of AMR trends in poultry production. While amoxicillin remains an effective treatment, the presence of multidrug-resistant strains and vancomycin-resistant isolates raises concerns regarding the potential dissemination of resistance genes. Future studies should incorporate next-generation sequencing to elucidate the genetic mechanisms underlying resistance. Additionally, integrating antibiotic usage data from farms may provide further insights into resistance dynamics. Strengthening antibiotic stewardship programs and fostering collaboration between veterinary and human medicine are crucial steps in addressing AMR under the One Health framework. Full article
(This article belongs to the Special Issue Detection of Bacteria and Antibiotics Surveillance in Livestock)
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18 pages, 3290 KiB  
Article
Antimicrobial Susceptibility Profiles of Commensal Escherichia coli Isolates from Turkeys in Hungarian Poultry Farms Between 2022 and 2023
by Ákos Jerzsele, Ádám Kerek, Franciska Barnácz, Bence Csirmaz, Ábel Szabó and László Kovács
Antibiotics 2025, 14(3), 305; https://doi.org/10.3390/antibiotics14030305 - 16 Mar 2025
Viewed by 660
Abstract
Background: The global spread of antimicrobial resistance (AMR) has prompted the critical importance of regular monitoring. Escherichia coli, a widely distributed facultative anaerobic pathogen, is significant both in terms of the clinical diseases that it causes and as a reservoir of [...] Read more.
Background: The global spread of antimicrobial resistance (AMR) has prompted the critical importance of regular monitoring. Escherichia coli, a widely distributed facultative anaerobic pathogen, is significant both in terms of the clinical diseases that it causes and as a reservoir of antimicrobial resistance, with notable implications for both animal and public health. Within the poultry industry, the turkey sector is an emerging and internationally significant branch. Methods: Our objective was to assess the antimicrobial resistance profile of commensal Escherichia coli strains isolated from large-scale turkey flocks in Hungary using minimum inhibitory concentration (MIC) determination. Results: A total of 470 isolates were analyzed, revealing that 61.5% of the strains were resistant to amoxicillin, while 18.5% were resistant to amoxicillin–clavulanic acid. The resistance observed against enrofloxacin (62.8%) and ceftriaxone (24%) is concerning. Comparison with human resistance data showed a similar resistance rate for amoxicillin and ampicillin, as well as amoxicillin–clavulanic acid and cephalosporins. However, for other active substances, the situation was significantly worse in veterinary medicine. Conclusions: The lower resistance to amoxicillin–clavulanic acid indicates that most strains are β-lactamase producers. Our findings underscore the necessity of regular and comprehensive surveillance, which can establish temporal trends over time. Incorporating data on antibiotic usage into future studies could facilitate the exploration of relevant correlations. Additionally, the next-generation sequencing of multidrug-resistant strains could help elucidate the genetic basis of resistance. Full article
(This article belongs to the Special Issue Detection of Bacteria and Antibiotics Surveillance in Livestock)
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15 pages, 1599 KiB  
Article
Monitoring the Spread of Multidrug-Resistant Escherichia coli Throughout the Broiler Production Cycle
by Victor Dellevedove Cruz, Danilo Henrique Rabaçal Alves, Jamile Kellen de Souza, Maísa Fabiana Menck-Costa, Bruno Henrique Dias de Oliva, Ana Angelita Sampaio Baptista, Alexandre Oba, Fabrizio Matté, Kácio Emílio Borges Baierle, Sérgio Paulo Dejato da Rocha, Kelly Cristina Tagliari de Brito, Benito Guimarães de Brito, Gerson Nakazato, Marcio Costa and Renata Katsuko Takayama Kobayashi
Antibiotics 2025, 14(1), 69; https://doi.org/10.3390/antibiotics14010069 - 10 Jan 2025
Viewed by 1313
Abstract
The extensive use of antimicrobials in broiler production is changing the bird microbiota, fostering drug-resistant bacteria, and complicating therapeutic interventions, making the problem of multidrug resistance global. The monitoring of antimicrobial virulence and resistance genes are tools that have come to assist the [...] Read more.
The extensive use of antimicrobials in broiler production is changing the bird microbiota, fostering drug-resistant bacteria, and complicating therapeutic interventions, making the problem of multidrug resistance global. The monitoring of antimicrobial virulence and resistance genes are tools that have come to assist the breeding of these animals, directing possible treatments as already used in human medicine and collecting data to demonstrate possible dissemination of multidrug-resistant strains that may cause damage to industry and public health. This work aimed to monitor broiler farms in southern Brazil, isolating samples of E. coli and classifying them according to the profile of resistance to antimicrobials of interest to human and animal health. We also monitored the profile of virulence genes and conducted an epidemiological survey of possible risk factors that contribute to this selection of multidrug-resistant isolates. Monitoring was carried out on farms in the three southern states of the country, collecting samples of poultry litter, cloacal swabs, and beetles of the species Alphitobius diaperinus, isolating E. coli from each of these samples. These were evaluated by testing their susceptibility to antimicrobials of animal and human interest; detecting whether the samples were extended-spectrum β-lactamase enzyme (ESBL) producers; and when positive, selected for genotypic tests to identify resistant genes (CTX-M, TEM, and SHV) and virulence. Among the antimicrobials tested, enrofloxacin and ciprofloxacin demonstrated some of the highest frequencies of resistance in the isolated strains, with significant statistical results. The use of these antimicrobials increased the likelihood of resistance by over three times and was associated with a 1.5-fold higher probability of multidrug resistance. Of all isolates, 95% were multidrug-resistant, raising concerns for production and public health. Among 231 ESBL-positive samples, the CTX-M1 group predominated. Full article
(This article belongs to the Special Issue Detection of Bacteria and Antibiotics Surveillance in Livestock)
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18 pages, 3067 KiB  
Article
Antimicrobial Susceptibility Profiles of Commensal Enterococcus spp. Isolates from Chickens in Hungarian Poultry Farms Between 2022 and 2023
by Ádám Kerek, Ábel Szabó and Ákos Jerzsele
Antibiotics 2024, 13(12), 1194; https://doi.org/10.3390/antibiotics13121194 - 7 Dec 2024
Viewed by 1088
Abstract
Background: The global spread of antimicrobial resistance (AMR) represents one of the most significant challenges of our generation. It is crucial to continuously monitor AMR, not only by investigating clinical, pathogenic strains but also by monitoring commensal bacterial strains, as they can serve [...] Read more.
Background: The global spread of antimicrobial resistance (AMR) represents one of the most significant challenges of our generation. It is crucial to continuously monitor AMR, not only by investigating clinical, pathogenic strains but also by monitoring commensal bacterial strains, as they can serve as natural reservoirs of resistance. Infections caused by Enterococcus species are increasingly recognized as emerging threats to both animal and public health. Among economically important livestock, poultry as a major source of animal protein for humans is a frequent carrier of enterococci, and also of sporadically detected clinical disease. Methods: This study aimed to determine the antimicrobial susceptibility profile of Enterococcus strains (n = 499) isolated from chicken farms in Hungary. The minimum inhibitory concentration (MIC) was determined for 15 antibiotics, including 10 with established clinical breakpoints. Results: The strains exhibited good sensitivity to amoxicillin, one of the first-line treatments for Enterococcus infections in veterinary medicine, with only 20.8% showing resistance. However, we observed an alarming 27.9% resistance rate to vancomycin, which is reserved to treat infections caused by multidrug-resistant strains in humans. A comparison of our findings with Hungarian hospital records revealed that the resistance patterns of poultry-derived Enterococcus faecalis strains were very similar to those of human isolates, particularly regarding penicillins and aminoglycosides. Conclusions: Overall, the increasing rates of AMR reinforce the importance of conducting periodic studies to establish long-term trends. For multidrug-resistant strains, next-generation sequencing is recommended to elucidate the genetic basis of resistance. Full article
(This article belongs to the Special Issue Detection of Bacteria and Antibiotics Surveillance in Livestock)
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19 pages, 2712 KiB  
Article
Antimicrobial Susceptibility Profiles of Commensal Escherichia coli Isolates from Chickens in Hungarian Poultry Farms Between 2022 and 2023
by Ádám Kerek, Ábel Szabó and Ákos Jerzsele
Antibiotics 2024, 13(12), 1175; https://doi.org/10.3390/antibiotics13121175 - 4 Dec 2024
Viewed by 1407
Abstract
Background: Widespread use of antibiotics has led to a global increase in resistance. The Escherichia coli bacterium is a facultative pathogen that often develops antibiotic resistance and is easily transmitted, not only in animal health but also in public health. Within the poultry [...] Read more.
Background: Widespread use of antibiotics has led to a global increase in resistance. The Escherichia coli bacterium is a facultative pathogen that often develops antibiotic resistance and is easily transmitted, not only in animal health but also in public health. Within the poultry sector, domestic fowl is widespread and one of the most dynamically growing sectors, which is why regular, extensive monitoring is crucial. Among economically important livestock, poultry as a major source of animal protein for humans is a frequent carrier of Escherichia coli, also with sporadically detected clinical disease. Methods: Our research evaluates the susceptibility of commensal Escherichia coli strains, isolated from large domestic fowl flocks in Hungary, to antibiotics of animal and public health importance, by determining the minimum inhibitory concentration value. Results: A total of 410 isolates were tested, with the highest level of resistance being found for florfenicol (62.7%). Particularly alarming are the resistance rates to enrofloxacin (52.9%), colistin (30.7%), and ceftriaxone (23.9%). We also found a resistance of 56.1% to amoxicillin and 22.2% to amoxicillin-clavulanic acid, which suggests that the majority of strains are β-lactamase-producing. When compared with the national human resistance data, we found with similar values for amoxicillin and amoxicillin-clavulanic acid, but the resistance rates of aminoglycosides, fluoroquinolones, and potency sulfonamide were worse in animal health. Conclusions: In conclusion, our results suggest that periodic surveys should be carried out and that long-term trends can be established that allow the monitoring of resistance patterns over time. For multidrug-resistant strains, new generation sequencing can be used to investigate the genetic background of resistance. Full article
(This article belongs to the Special Issue Detection of Bacteria and Antibiotics Surveillance in Livestock)
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18 pages, 1110 KiB  
Article
Commercial Day-Old Chicks in Nigeria Are Potential Reservoirs of Colistin- and Tigecycline-Resistant Potentially Pathogenic Escherichia coli
by Madubuike Umunna Anyanwu, Nkechi Harriet Ikenna-Ezeh, Simeon Chibuko Okafor, Chinaza Francisca Ezemuoka, Obichukwu Chisom Nwobi, Temitope Mofoluso Ogunniran, Lynda Onyinyechi Obodoechi, Onyinye Josephine Okorie-Kanu, Anthony Christian Mgbeahuruike, Ifeyinwa Riona Okosi and Ishmael Festus Jaja
Antibiotics 2024, 13(11), 1067; https://doi.org/10.3390/antibiotics13111067 - 10 Nov 2024
Cited by 1 | Viewed by 1489
Abstract
Background: Frequent use of colistin (COL) and tetracyclines in the Nigerian poultry sector potentially triggers bacterial resistance against COL and tigecycline (TIG), which are last-line antibiotics used to treat multidrug-resistant infections. Aim/Objectives: This study aimed to isolate COL- and TIG-resistant E. coli [...] Read more.
Background: Frequent use of colistin (COL) and tetracyclines in the Nigerian poultry sector potentially triggers bacterial resistance against COL and tigecycline (TIG), which are last-line antibiotics used to treat multidrug-resistant infections. Aim/Objectives: This study aimed to isolate COL- and TIG-resistant E. coli from commercial day-old chicks distributed to poultry farmers in Nsukka Southeastern Nigeria, assess the production of extended-spectrum β-lactamase (ESBL) and carbapenemase by the isolates, and establish their pathogenic potentials. Materials and Methods: Non-duplicate cloacal swabs were systematically collected from 250 randomly selected day-old chicks. MacConkey agar with 1 µg/mL of COL and 16 µg/mL of tetracycline was used for the isolation of putative COL- and tetracycline-resistant E. coli, respectively. E. coli isolates were confirmed biochemically using the API20E Gram-negative identification kit and molecularly by polymerase chain reaction targeting the uidA gene. Phenotypic COL resistance was established using COL agar and COL disc elution tests, while TIG insusceptibility was determined with disc diffusion. ESBL and carbapenemase production was assessed by double-disc synergy and modified carbapenem inactivation methods, respectively. Pathogenic potentials were determined using phenotypic methods. Results: COL- and TIG-resistant E. coli was recovered from 95 (38.0%) and 62 (24.8%) swabs from the 250 chicks, respectively. None of the isolates were potential ESBL or carbapenemase producers. The COL-resistant isolates displayed pathogenic potentials such as biofilm formation, haemagglutination, cell surface hydrophobicity, surface layer, and gelatinase activities at rates of 30.7%, 8.4%, 33.7%, 23.5%, and 17.6%, respectively. Meanwhile, the TIG-resistant isolates exhibited their respective potentials at rates of 47.0%, 21.0%, 35.5%, 58.1%, and 43.6%. Red, dry, and rough (RDAR) was the predominant curli fimbriae, and the cellulose morphotype portrayed by both the COL- and TIG-unsusceptible potential biofilm-producing isolates. Conclusions: This study demonstrates that a significant percentage of commercial day-old chicks distributed to farmers in Nsukka, southeastern Nigeria, are colonized by potentially pathogenic COL- and TIG-resistant E. coli, which could spread to humans and the environment. Full article
(This article belongs to the Special Issue Detection of Bacteria and Antibiotics Surveillance in Livestock)
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17 pages, 1532 KiB  
Article
Antimicrobial Resistance Profile, Whole-Genome Sequencing and Core Genome Multilocus Sequence Typing of B. anthracis Isolates in Croatia from 2001 to 2022
by Gordan Kompes, Sanja Duvnjak, Irena Reil, Željko Mihaljević, Boris Habrun, Miroslav Benić, Luka Cvetnić, Silvio Špičić and Antonela Bagarić
Antibiotics 2024, 13(7), 639; https://doi.org/10.3390/antibiotics13070639 - 11 Jul 2024
Cited by 1 | Viewed by 1843
Abstract
Bacillus anthracis, the causative agent of anthrax disease, is a worldwide threat to livestock, wildlife and public health. It is also considered one of the most important pathogens of bioterrorism. Rapid and reliable diagnosis and administration of antimicrobials are essential for effective [...] Read more.
Bacillus anthracis, the causative agent of anthrax disease, is a worldwide threat to livestock, wildlife and public health. It is also considered one of the most important pathogens of bioterrorism. Rapid and reliable diagnosis and administration of antimicrobials are essential for effective anthrax treatment. In this study, we determined the in vitro susceptibilities of 40 isolates of B. anthracis isolated in Croatia over the recent two decades to 18 antimicrobials. Whole-genome sequencing was performed, and bioinformatics tools were used to determine virulence factors and antimicrobial resistance genes. Core genome-based multilocus sequence typing was used for isolate comparison and phylogenetic analysis. All isolates were susceptible to all antimicrobials recommended for post-exposure prophylaxis or anthrax therapy. Susceptibility was found to all other tested antimicrobials that are an alternative for primary therapy. We found two beta-lactamase genes, but their expression is not sufficient to confer resistance. In all isolates used in this study, we found 21 virulence genes, 8 of which are responsible for toxin and capsule production. As far as phylogenetic analysis is concerned, the B. anthracis isolates from Croatia are categorised into two clades. The first is clade A, subclade Trans Eurasia, and the other is clade B, subclade B2. Full article
(This article belongs to the Special Issue Detection of Bacteria and Antibiotics Surveillance in Livestock)
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14 pages, 289 KiB  
Article
Occurrence of Antimicrobial-Resistant Enterococcus spp. in Healthy Chickens Never Exposed to Antimicrobial Agents in Central Italy
by Giulia Cagnoli, Alessia Di Paolo, Fabrizio Bertelloni, Sonia Salvucci, Arianna Buccioni, Margherita Marzoni Fecia di Cossato and Valentina Virginia Ebani
Antibiotics 2024, 13(5), 417; https://doi.org/10.3390/antibiotics13050417 - 1 May 2024
Viewed by 2274
Abstract
Enterococci are part of the natural flora of the gastrointestinal tract of mammals, including humans, birds and invertebrates. They can cause infection, mainly among hospitalized patients, as well as acquire and transfer antimicrobial resistance genes. The present study allowed the isolation of 98 [...] Read more.
Enterococci are part of the natural flora of the gastrointestinal tract of mammals, including humans, birds and invertebrates. They can cause infection, mainly among hospitalized patients, as well as acquire and transfer antimicrobial resistance genes. The present study allowed the isolation of 98 Enterococcus (73.47% E. faecium, 23.47% E. faecalis, 3.06% E. avium) strains from 120-day-old healthy chickens that had never been treated with antimicrobials. Their antimicrobial resistance was evaluated by the agar disk diffusion method; high-level aminoglycoside (streptomycin and gentamicin) and vancomycin resistance were established using the microbroth dilution method. The highest percentages of resistant isolates were detected with quinupristin–dalfopristin (88.78%), rifampicin (64.29%), tetracyclines (45.92%), and enrofloxacin (41.84%). High percentages of susceptible strains were found with teicoplanin (100%), amoxicillin–clavulanic acid (97.96%), nitrofurantoin (94.90%), ampicillin (92.86%), chloramphenicol (90.82%), and linezolid (88.78%). About 60% of the strains were classified as MDR (multidrug-resistant). Moreover, PCR was carried out to investigate genes encoding for tetracyclines resistance determinants: tet(M), tet(L), tet(O), tet(K), and Int-Tn. Genes were detected in 68 (69.38%) strains: 36 were shown to be resistant with the agar disk diffusion method, while 28 were intermediate, and 2 were susceptible. The present study showed that chickens never treated with antimicrobials potentially harbor enterococci having phenotypic and genotypic characters of antimicrobial resistance. Full article
(This article belongs to the Special Issue Detection of Bacteria and Antibiotics Surveillance in Livestock)
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