Molecular characterisation of multi-drug resistant Escherichia coli of bovine origin

Antimicrobial efficiency of bromhexine hydrochloride against endometritis-causing Escherichia coli and Trueperella pyogenes in bovines

In this study, the main agents associated with endometritis in cows in the state of Santa Catarina, Brazil, were identified and the resistance profile and virulence mechanisms of the bacterial isolates were evaluated. Isolates of Escherichia coli and Trueperella pyogenes were tested for their biofilm forming ability and the antimicrobial action of bromhexine hydrochloride in combination with other antimicrobials. A total of 37 uterine lavage samples were collected from cows with endometritis. Of the 55 bacteria isolated, 25.4% were identified as T. pyogenes and 16.3% as E. coli. The bacterial isolates showed greater resistance to sulfamethoxazole + trimethoprim (58.2%) and tetracycline (56.3%). Among the species, E. coli showed the highest resistance rates, with 100% of isolates showing resistance to amoxicillin, streptomycin, and gentamicin. The results of the minimum inhibitory concentration for the T. pyogenes isolates showed that 91.6% of the isolates were resistant to enrofloxacin and tetracycline, and 75% were resistant to ceftiofur and sulfamethoxazole + trimethoprim. All E. coli and T. pyogenes isolates showed biofilm forming ability. The plo, fimA, and nanH genes were identified in 100% of T. pyogenes isolates. In parallel, 100% of E. coli isolates had the fimH gene, and 11.1% had the csgD gene. Bromhexine hydrochloride showed antimicrobial activity against 100% of E. coli isolates and 66.6% of T. pyogenes isolates. Furthermore, when associated with antimicrobials, bromhexine hydrochloride has a synergistic and additive effect, proving to be an option in the treatment of endometritis in cows and an alternative for reducing the use of antimicrobials.

Stenotrophomonas riyadhensis sp. nov., isolated from a hospital floor swab

During the analysis of a collection of Pseudomonas strains linked to an outbreak in an intensive care unit at King Faisal Specialist Hospital and Research Center in 2019, one isolate (CFS3442T) was identified phenotypically as Pseudomonas aeruginosa. However, whole-genome sequencing revealed its true identity as a member of the genus Stenotrophomonas, distinct from both P. aeruginosa and Stenotrophomonas maltophilia. The isolate demonstrated: (i) a significant phylogenetic distance from P. aeruginosa; (ii) considerable genomic differences from several S. maltophilia reference strains and other Stenotrophomonas species; and (iii) unique phenotypic characteristics. Based on the combined geno- and phenotypic data, we propose that this isolate represents a novel species within the genus Stenotrophomonas, for which the name Stenotrophomonas riyadhensis sp. nov. is proposed. The type strain is CFS3442T (=NCTC 14921T=LMG 33162T).

Multidrug-resistant Shiga toxin-producing Escherichia coli and hybrid pathogenic strains of bovine origin

Antimicrobial-resistant Escherichia coli strains have been circulating in various sectors and can be cross-transferred between them. Among pathogenic E. coli strains, Shiga toxin-producing E. coli (STEC) and hybrid pathogenic E. coli (HyPEC) emerged as responsible for outbreaks worldwide. As bovine are reservoir of STEC strains, these pathogens primarily spread to food products, exposing humans to risk. Therefore, this study aimed to characterize antimicrobial-resistant and potentially pathogenic E. coli strains from fecal samples of dairy cattle. In this regard, most E. coli strains (phylogenetic groups A, B1, B2, and E) were resistant to β-lactams and non-β-lactams and were classified as multidrug-resistant (MDR). Antimicrobial resistance genes (ARGs) related to multidrug resistance profiles were detected. Furthermore, mutations in fluoroquinolone and colistin resistance determinants were also identified, highlighting the deleterious mutation His152Gln in PmrB that may have contributed to the high level (> 64 mg/L) of colistin resistance. Virulence genes of diarrheagenic and extraintestinal pathogenic E. coli (ExPEC) pathotypes were shared among strains and even within the same strain, evidencing the presence of HyPEC (i.e., ExPEC/STEC), which were assigned as unusual B2-ST126-H3 and B1-ST3695-H31. These findings provide phenotypic and molecular data of MDR, ARGs-producing, and potentially pathogenic E. coli strains in dairy cattle, contributing to the monitoring of antimicrobial resistance and pathogens in healthy animals and alerting to potential bovine-associated zoonotic infections.

Extended-Spectrum β-Lactamases (ESBL) Producing Bacteria in Animals

Animals have been identified as potential reservoirs and vectors of resistance genes, with studies showing that Gram-negative bacteria can acquire resistance through the horizontal transmission of resistance genes on plasmids. It is important to understand the distribution of antimicrobial-resistant bacteria and their drug-resistant genes in animals. Previous review articles mostly focused on a single bacterium or a single animal. Our objective is to compile all ESBL-producing bacteria isolated from various animals in recent years and provide a comprehensive viewpoint. Using a thorough PubMed literature search spanning from 1 January 2020 to 30 June 2022, studies exploring extended-spectrum beta-lactamase (ESBL) producing bacteria in animals were included. ESBL-producing bacteria are present in animals from various countries around the world. The most common sources of these bacteria were farm animals, and the most frequently isolated bacteria were Escherichia coli and Klebsiella pneumoniae. The most detected ESBL genes were blaTEM, blaSHV, and blaCTX-M. The presence of ESBL-producing bacteria in animals highlights the importance of the One Health approach to address the issue of antibiotic resistance. Further research is needed to better understand the epidemiology and mechanisms of the spread of ESBL-producing bacteria in animal populations and their potential impact on human and animal health.

Effects of Artemisinin on Escherichia coli-Induced Mastitis in Bovine Mammary Epithelial Cells and Mice

Bovine mastitis is an important disease affecting dairy farming, and it causes large economic losses to the dairy industry. Escherichia coli (E. coli) is considered to be a causative environmental pathogen and frequently enters into mammary glands, causing inflammation. Artemisinin is a highly effective malaria remedy and is not easy to develop drug resistance to. In recent years, other effects of artemisinin (including antitumor, anti-inflammatory, antifungal, etc.) have been increasingly discovered and applied. The current study aimed to investigate whether artemisinin could attenuate E. coli-induced inflammation. Through the E. coli mastitis model in MAC-T cells and mice, the protective effects of artemisinin were analyzed by CCK-8 (Cell Counting Kit-8), Western blot, and RT-qPCR. The results showed that artemisinin reversed the decrease of cell viability and upregulated TLR4 (toll-like receptor 4)/NF-κB (nuclear factor κB) and MAPK (mitogen activated protein kinase)/p38 signaling pathways, as well as restrained the expression of TNF-α, IL-6, and IL-1β mRNA caused by E. coli. Meanwhile, artemisinin also alleviated mammary tissue damage, reduced inflammatory cells' infiltration, and decreased the levels of inflammatory factors in a mice mastitis model. This study demonstrated that artemisinin alleviated the inflammatory response of mouse mastitis and MAC-T cells induced by E. coli, thus providing a practical approach for the clinical control of mastitis.

Phenotypic and molecular characterizations of multidrug-resistant diarrheagenic E. coli of calf origin

Escherichia coli has become one of the most important causes of calf diarrhea. The aim of this study is to determine the patterns of antimicrobial resistance of E. coli isolates from six cattle farms and to identify prominent resistance genes and virulence genes among the strains isolated from the diarrhea of calves. Antimicrobial susceptibility tests were performed using the disk diffusion method, and PCR was used to detect resistance and virulence genes. The prevalence of multidrug resistant (MDR) E. coli was 77.8% in dairy cattle and 63.6% in beef cattle. There were high resistance rates to penicillin (100%, 100%) and ampicillin (96.3%, 86.4%) in E. coli from dairy cattle and beef cattle. Interestingly, resistance rate to antimicrobials and distribution of resistance genes in E. coli isolated from dairy cattle were higher than those in beef cattle. Further analysis showed that the most prevalent resistance genes were blaTEM and aadA1 in dairy cattle and beef cattle, respectively. Moreover, seven diarrheagenic virulence genes (irp2, fyuA, Stx1, eaeA, F41, K99 and STa) were present in the isolates from dairy cattle, with a prevalence ranging from 3.7% to 22.22%. Six diarrheagenic virulence genes (irp2, fyuA, Stx1, eaeA, hylA and F41) were identified in the isolates from beef cattle, with a prevalence ranging from 2.27% to 63.64%. Our results provide important evidence for better exploring their interaction mechanism. Further studies are also needed to understand the origin and transmission route of E. coli in cattle to reduce its prevalence.

Characterisation of Early Positive mcr-1 Resistance Gene and Plasmidome in Escherichia coli Pathogenic Strains Associated with Variable Phylogroups under Colistin Selection

An antibiotic susceptibility monitoring programme was conducted from 2004 to 2010, resulting in a collection of 143 Escherichia coli cultured from bovine faecal samples (diarrhoea) and milk-aliquots (mastitis). The isolates were subjected to whole-genome sequencing and were distributed in phylogroups A, B1, B2, C, D, E, and G with no correlation for particular genotypes with pathotypes. In fact, the population structure showed that the strains belonging to the different phylogroups matched broadly to ST complexes; however, the isolates are randomly associated with the diseases, highlighting the necessity to investigate the virulence factors more accurately in order to identify the mechanisms by which they cause disease. The antimicrobial resistance was assessed phenotypically, confirming the genomic prediction on three isolates that were resistant to colistin, although one isolate was positive for the presence of the gene mcr-1 but susceptible to colistin. To further characterise the genomic context, the four strains were sequenced by using a single-molecule long read approach. Genetic analyses indicated that these four isolates harboured complex and diverse plasmids encoding not only antibiotic resistant genes (including mcr-1 and bla) but also virulence genes (siderophore, ColV, T4SS). A detailed description of the plasmids of these four E. coli strains, which are linked to bovine mastitis and diarrhoea, is presented for the first time along with the characterisation of the predicted antibiotic resistance genes. The study highlighted the diversity of incompatibility types encoding complex antibiotic resistance elements such as Tn6330, ISEcp1, Tn6029, and IS5075. The mcr-1 resistance determinant was identified in IncHI2 plasmids pCFS3273-1 and pCFS3292-1, thus providing some of the earliest examples of mcr-1 reported in Europe, and these sequences may be a representative of the early mcr-1 plasmidome characterisation in the EU/EEA.

Whole-genome Sequencing to Track Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Transmission in Nosocomial Outbreaks

Background

During the first wave of the coronavirus disease 2019 (COVID-19) pandemic, outbreaks of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in healthcare institutions posed a significant problem. Due to limited evidence, guidance on appropriate infection prevention and control (IPC) measures such as the wearing of face masks varied. Here, we applied whole virus genome sequencing (WvGS) to analyse transmission routes of SARS-CoV-2 in hospital-acquired (HA) COVID-19.

Methods

An investigation was undertaken for all HA cases of COVID-19 from March to April 2020. Fifty SARS-CoV-2 samples were analysed by WvGS and their phylogenetic relationship established.

Results

WvGS identified transmission events previously undetected by epidemiological analysis and provided evidence for SARS-CoV-2 transmission between healthcare workers (HCW) and patients and among HCW themselves. The majority of HA COVID-19 cases occurred in patients highly dependent on nursing care, suggesting the likely route of transmission was by close contact or droplet, rather than aerosol, transmission. Mortality among HA COVID-19 infections was recorded as 33%.

Conclusions

This study provides evidence that SARS-CoV-2 transmission occurs from symptomatic and asymptomatic HCWs to patients. Interventions including comprehensive screening of HCWs for COVID-19 symptoms, PCR testing of asymptomatic HCWs upon identification of HA cases and implementation of universal use of surgical masks for all clinical care is indicated to prevent viral transmission. Our study highlights the importance of close collaboration between guidance bodies and frontline IPC experts for developing control measures in an emergency pandemic situation caused by a virus with undefined transmission modus.

Levofloxacin in veterinary medicine: a literature review

A potent third-generation antimicrobial fluoroquinolone drug, levofloxacin was introduced into human clinical practice in 1993. Levofloxacin is also used in veterinary medicine, however its use is limited: it is completely banned for veterinary use in the EU, and used extralabel in only companion animals in the USA. Since its introduction to clinical practice, many studies have been published on levofloxacin in animal species, including pharmacokinetic studies, tissue drug depletion, efficacy, and animal microbial isolate susceptibility to levofloxacin. This literature overview highlights the most clinically relevant and scientifically important levofloxacin studies linked to the field of veterinary medicine.

Multidrug Resistance of Escherichia coli Strains Isolated From Bovine Feces and Carcasses in Northeast Mexico

In this work, the antimicrobial resistance profile of Escherichia coli strains (n = 248) isolated from bovine feces and carcass samples from Tamaulipas, Mexico, was evaluated. Susceptibility to 12 antibiotics conventionally used in human and veterinary treatments was determined according to Clinical and Laboratory Standards Institute guidelines. Genes encoding resistance to tetracycline (tetA and tetB), streptomycin (strA), aminoglycoside (aadA), and β-lactamase (bla_TEM and bla_SHV) were investigated by PCR. Also, stx1, stx2, eae, bfp, and hlyA encoding virulence factors were determined. Of the isolates, 85.9% were confirmed as E. coli strains. Among the 213 E. coli isolates tested, 94.8% (202/213) showed resistance for at least one antimicrobial, mainly ampicillin (83.0%; 177/213), cephalothin (76.0%; 162/213), and tetracyclines (69.0%; 147/213). In all the other antibiotics tested, the resistance percentage was below 36%. A multidrug-resistant phenotype was found in 72.7% of the tested strains. The presence of the tet gene (tetA or tetB) was detected in 43.1% of the isolates, the strA gene in 17.3%, and aadA1 in 51.6%. The bla_TEM and bla_SHV genes were found in 10.3 and 0.4% of the isolates, respectively. stx1 was detected in 4.2% of isolates, stx2 in 7.0, and hlyA in 2.8%. The virulence genes, eae and bfp, were not detected in any strain. These results indicate that Tamaulipas food products of bovine origin can be a source of multiresistant E. coli strains for the environment and exposure for consumers.