Effect of Nk-lysin peptides on bacterial growth, MIC, antimicrobial resistance, and viral activities

NK-lysins from chicken, bovine and human are used as antiviral and antibacterial agents. Gram-negative and gram-positive microorganisms, including Streptococcus pyogenes, Streptococcus mutans, Escherichia coli, Pseudomonas aeruginosa, Klebsiella oxytoca, Shigella sonnei, Klebsiella pneumoniae and Salmonella typhimurium, are susceptible to NK-lysin treatment. The presence of dominant TEM-1 gene was noted in all untreated and treated bacteria, while TOHO-1 gene was absent in all bacteria. Importantly, β-lactamase genes CTX-M-1, CTX-M-8, and CTX-M-9 genes were detected in untreated bacterial strains; however, none of these were found in any bacterial strains following treatment with NK-lysin peptides. NK-lysin peptides are also used to test for inhibition of infectivity, which ranged from 50 to 90% depending on NK-lysin species. Chicken, bo vine and human NK-lysin peptides are demonstrated herein to have antibacterial activity and antiviral activity against Rotavirus (strain SA-11). On the basis of the comparison between these peptides, potent antiviral activity of bovine NK-lysin against Rotavirus (strain SA-11) is particularly evident, inhibiting infection by up to 90%. However, growth was also significantly inhibited by chicken and human NK-lysin peptides, restricted by 80 and 50%, respectively. This study provided a novel treatment using NK-lysin peptides to inhibit expression of β-lactamase genes in β-lactam antibiotic-resistant bacterial infections.

Assessing the risk of exposure to antimicrobial resistance at public beaches: Genome-based insights into the resistomes, mobilomes and virulomes of beta-lactams resistant Enterobacteriaceae from recreational beaches in Lagos, Nigeria

The role of recreational water use in the acquisition and transmission of antimicrobial resistance (AMR) is under-explored in low- and middle-income countries (LMICs). We used whole genome sequence analysis to provide insights into the resistomes, mobilomes and virulomes of 14 beta-lactams resistant Enterobacterales isolated from water and wet-sand at four recreational beaches in Lagos, Nigeria. Carriage of multiple beta-lactamase genes was detected in all isolates except two, including six isolates carrying blaNDM-1. Most detected antibiotic resistance genes (ARGs) were located within a diverse landscape of plasmids, insertion sequences and transposons including the presence of ISKpn14 upstream of blaNDM-1 in a first report in Africa. Virulence genes involved in adhesion and motility as well as secretion systems are particularly abundant in the genomes of the isolates. Our results confirmed the four beaches are contaminated with bacteria carrying clinically relevant ARGs associated with mobile genetic elements (MGE) which could promote the transmission of ARGs at the recreational water-human interface.

Beta-lactamase genes in bacteria from food animals, retail meat, and human surveillance programs in the United States from 2002 to 2021

The spread of beta-lactamase-producing bacteria is a global public-health concern. This study aimed to explore the distribution of beta-lactamases reported in three sampling sources (cecal, retail meat, and human) collected as part of integrated surveillance in the United States. We retrieved and analyzed data from the United States National Antimicrobial Resistance Monitoring Systems (NARMS) from 2002 to 2021. A total of 115 beta-lactamase genes were detected in E. coli, Salmonella enterica, Campylobacter, Shigella and Vibrio: including 35 genes from cecal isolates, 32 genes from the retail meat isolates, and 104 genes from the human isolates. Three genes in E. coli (blaCMY-2,blaTEM-1A, and blaTEM-1B), 6 genes in Salmonella enterica (blaCARB-2, blaCMY-2, blaCTXM-65, blaTEM-1A, blaTEM-1B, and blaHERA-3), and 2 genes in Campylobacter spp. (blaOXA-61 and blaOXA-449) have been detected across food animals (cattle, chicken, swine, and turkey) and humans over the study period. blaCTXM-55 has been detected in E. coli isolates from the four food animal sources while blaCTXM-15 and blaCTXM-27 were found only in cattle and swine. In Salmonella enterica, blaCTXM-2, blaCTXM-9, blaCTXM-14, blaCTXM-15, blaCTXM-27, blaCTXM-55, and blaNDM-1 were only detected among human isolates. blaOXAs and blaCARB were bacteria-specific and the only beta-lactamase genes detected in Campylobacter spp. and Vibrio spp respectively. The proportions of beta-lactamase genes detected varies from bacteria to bacteria. This study provided insights on the beta-lactamase genes detected in bacteria in food animals and humans in the United States. This is necessary for better understanding the molecular epidemiology of clinically important beta-lactamases in one health interface.

coli from wastewater treatment plant

BACKGROUND

The World Health Organization (WHO) recently classified Enterobacteriaceae resistance to third-generation cephalosporin into the group of pathogens with critical criteria for future research.

METHODS

A study to assess the antibiogram and beta-lactamase genes among the cefotaxime resistant E. coli (CREc) from a South African wastewater treatment plant (WWTP) was conducted using standard phenotypic and molecular biology characterization methods.

RESULTS

Approximate total E. coli (TEc) concentration (log₁₀ CFU/mL) ranged between 5.7 and 6.8 among which cefotaxime resistant E. coli were between 1.8 and 4.8 (log₁₀ CFU/mL) for cefotaxime antibiotic concentration of 4 and 8 mg/L in the influent samples. Effluent samples, heavily influenced by the chlorination had only 0.3 log₁₀ CFU/mL of TEc. Fifty-one cefotaxime resistant isolates were selected out of an overall of 75 isolates, and subjected to a new round of testing, with a follow up of 36 and 48 isolates for both colistin and gentamicin, respectively as guided by initial results. Selected CREc exhibited resistance to amoxicillin-clavulanic acid (35.3%; n = 51), colistin sulphate (76.5%; n = 36), ciprofloxacin (47.1%; n = 51), gentamicin (87.5%; n = 48) and intermediate-resistance to meropenem (11.8%; n = 51). Extended spectrum-beta-lactamase genes detected, viz.: bla_CTX-M (52.6%; n = 38) and bla_TEM (84.2%; n = 38) and concurrent bla_CTX-M + bla_TEM (36.8%; n = 38), but no bla_SHV was detected. Carbapenem resistance genes, blaKPC-2 (15.8%; n = 38), blaOXA-1 (57.9%; n = 38), blaNDM-1 (15.8%; n = 38) were also detected. Approximately, 10.5 - 36.8% (n = 38) co-occurrence of two or more beta-lactamase genes was detected in some isolates. Out of the selected number (n = 30), 7(23.3%) were enterotoxigenic E. coli (ETEC), 14 (46.7%) were Enteroaggregative E. coli (EAEC), but no enteropathogenic E. coli (EPEC) was detected.

CONCLUSION

Resistance to cefotaxime and the presence of a wide range of beta-lactamase genes exposed the potential risks associated with these pathogens via occupational and domestic exposure during the reuse of treated wastewater.

Antimicrobial resistance genes in Salmonella and Escherichia coli isolates from chicken droppings in Nairobi, Kenya

OBJECTIVE

Increase in antimicrobial resistance is a threat to health sector globally. Surveillance on the spread and emergence of antimicrobial resistance is therefore invertible. This study investigated prevalence of Salmonella and Escherichia coli, molecularly characterized their antimicrobial resistance patterns and spread among resistant isolates from chicken droppings.

RESULTS

A total of 150 chicken households were selected randomly within Nairobi and fresh chicken droppings collected. Salmonella and Escherichia coli were isolated and antimicrobial susceptibility test carried out. Beta-lactamase genes and class 1 integrons were determined among amoxicillin resistant isolates. Isolates carrying TEM gene were further subjected to (GTG)₅ PCR genotyping. Of the analysed samples, 57% and 12% contained Escherichia coli and Salmonella respectively. Most of the isolates were susceptible to the tested antibiotics with exemption of 53% of the isolates that were resistant to amoxicillin. The isolates were detected with TEM (46%), CTX-M (18%) resistance genes and class 1 integrons (25%). The study reveals presence of beta-lactamase genes and class 1 integrons across Salmonella and Escherichia coli isolates from droppings of reared chicken. Therefore, the wide distribution of chicken and their fecal waste is likely to increase development of antibiotic resistance.

Development of a multiplex PCR assay for the detection and differentiation of Burkholderia pseudomallei, Burkholderia mallei, Burkholderia thailandensis, and Burkholderia cepacia complex

Two species of Burkholderia pseudomallei complex (Bpc), B. pseudomallei and B. mallei, can cause severe life-threatening infections. Rapidly discerning individual species within the group and separating them from other opportunistic pathogens of the Burkholderia cepacia complex (Bcc) is essential to establish a correct diagnosis and for epidemiological surveillance. In this study, a multiplex PCR assay based on the detection of an individual set of chromosomal beta-lactamase genes for single-step identification and differentiation of B. pseudomallei, B. mallei, B. thailandensis, and Bcc was developed. Two pairs of primers specific to a distinct class of B metallo-beta-lactamase genes and a pair of primers specific to the oxacillin-hydrolyzing class D beta-lactamase gene were demonstrated to successfully discriminate species within Bpc and from Bcc. The assay sensitivity was 9561 genomic equivalents (GE) for B. pseudomallei, 7827 GE for B. mallei, 8749 GE for B. thailandensis and 6023 GE for B. cepacia.