Extended-Spectrum Beta-Lactamase-Producing Enterobacteriaceae in Fresh Produce

Magnitude of extended-spectrum β-lactamase and carbapenemase producing Enterobacteriaceae among commonly vended street foods in Arba Minch town, southern Ethiopia

BACKGROUND

The rising prevalence of extended-spectrum beta-lactamase and carbapenemase-producing Enterobacteriaceae (ESβL-PE) in street foods poses a significant risk to human health due to its epidemiological significance. Thus, the aim of this study was to determine the magnitude of foodborne Enterobacteriaceae that produce carbapenemase and ESβL, as well as their patterns of antibiotic resistance, in the studied area.

METHODS

A community-based cross-sectional study was carried out from January 1st, 2023, to February 30th, 2023. One hundred randomly chosen street-vended food items (one hundred grams of each food item) were aseptically collected, and aliquots of 0.1 ml from the homogenized (25 g of samples into 225 ml of buffered peptone water (BPW)) were inoculated on MacConkey agar and Xylose Lysine Deoxycholate Agar (XLD). Enterobacteriaceae isolates were identified using various biochemical tests. ESβL and carbapenemase were first screened by indicator cephalosporins and carbapenem antibiotics, respectively. ESβL and carbapenemase were confirmed by a double-disc synergy test and modified carbapenem inactivation methods, respectively. Kirby-Bauer disc diffusion method was used for the antimicrobial-resistant test.

RESULTS

A total of 112 Enterobacteriaceae belonging to six different genera were isolated. E. coli was attributed 39 (34.8%), followed by Citrobacter spp. 22 (19.6%) and K. pneumoniae 18 (16.1%), with only 8 (7.1%) isolated Salmonella spp. About 15.2% (n = 17) and 8.9% (n = 10) of Enterobacteriaceae were phenotypically confirmed to be extended-spectrum beta-lactamase (ESβL) and carbapenemase producers, respectively. The highest percentage of ESβL-producing isolates was attributed to K. pneumoniae (n = 5), E. coli (n = 4), and Enterobacter spp. (n = 3). Proteus spp. and Salmonella spp. isolates were carbapenemase-negative. All carbapenemase-positive isolates were found to be ESβL-producers. 70.6% (12/17) of ESβL-producing Enterobacteriaceae were found to be multidrug-resistant (MDR).

CONCLUSION

A considerable number of multidrug-resistant ESβL and carbapenemase-producing Enterobacteriaceae were identified, suggesting that street foods may be a potential source of MDR foodborne infections. Consequently, it is important to conduct routine examinations of street food items and track trends in medication resistance.

Resistance to β-lactams in Enterobacteriaceae isolated from vegetables: a review

Vegetables are crucial for a healthy human diet due to their abundance of essential macronutrients and micronutrients. However, there have been increased reports of antimicrobial-resistant Enterobacteriaceae isolated from vegetables. Enterobacteriaceae is a large group of Gram-negative bacteria that can act as commensals, intestinal pathogens, or opportunistic extraintestinal pathogens. Extraintestinal infections caused by Enterobacteriaceae are a clinical concern due to antimicrobial resistance (AMR). β-lactams have high efficacy against Gram-negative bacteria and low toxicity for eukaryotic cells. These antimicrobials are widely used in the treatment of Enterobacteriaceae extraintestinal infections. This review aimed to conduct a literature survey of the last five years (2018-2023) on the occurrence of β-lactam-resistant Enterobacteriaceae in vegetables. Research was carried out in PubMed, Web of Science, Scopus, ScienceDirect, and LILACS (Latin American and Caribbean Health Sciences Literature) databases. After a careful evaluation, thirty-seven articles were selected. β-lactam-resistant Enterobacteriaceae, including extended-spectrum β-lactamases (ESBLs)-producing, AmpC β-lactamases, and carbapenemases, have been isolated from a wide variety of vegetables. Vegetables are vectors of β-lactam-resistant Enterobacteriaceae, contributing to the dissemination of resistance mechanisms previously observed only in the hospital environment.

Occurrence, Typing, and Resistance Genes of ESBL/AmpC-Producing Enterobacterales in Fresh Vegetables Purchased in Central Israel

Beta-lactam resistance can lead to increased mortality, higher healthcare expenses, and limited therapeutic options. The primary mechanism of beta-lactam resistance is the production of extended-spectrum beta-lactamases (ESBL) and AmpC beta-lactamases. The spread of beta-lactamase-producing Enterobacterales via the food chain may create a resistance reservoir. The aims of this study were to determine the prevalence of ESBL/AmpC-producing Enterobacterales in vegetables, to examine the association between EBSL/AmpC-producing bacteria and types of vegetables, packaging, and markets, and to investigate the genetic features of ESBL-producing isolates. The antibiotic susceptibilities were determined using VITEK. Phenotypic ESBL/AmpC production was confirmed using disk diffusion. ESBL-producing isolates were subjected to Fourier-transform infrared (FT-IR) spectroscopy and to whole genome sequencing using Oxford Nanopore sequencing technology. Of the 301 vegetable samples, 20 (6.6%) were positive for ESBL producers (16 Klebsiella pneumoniae and 4 Escherichia coli), and 63 (20.9%) were positive for AmpC producers (56 Enterobacter cloacae complex, 4 Enterobacter aerogenes/cancerogenus, and 3 Pantoea spp., Aeromonas hydrophila, and Citrobacter braakii). The blaCTX-M and blaSHV genes were most common among ESBL-producing isolates. The beta-lactamase genes of the ESBL producers were mainly carried on plasmids. Multilocus sequence typing and FT-IR typing revealed high diversity among the ESBL producers. AmpC producers were significantly more common in leafy greens and ESBL producers were significantly less common in climbing vegetables. The presence of ESBL/AmpC-producing Enterobacterales in raw vegetables may contribute to the dissemination of resistance genes in the community.

Cytotoxicity and Antimicrobial Resistance of Aeromonas Strains Isolated from Fresh Produce and Irrigation Water

The genus Aeromonas has received constant attention in different areas, from aquaculture and veterinary medicine to food safety, where more and more frequent isolates are occurring with increased resistance to antibiotics. The present paper studied the interaction of Aeromonas strains isolated from fresh produce and water with different eukaryotic cell types with the aim of better understanding the cytotoxic capacity of these strains. To study host-cell pathogen interactions in Aeromonas, we used HT-29, Vero, J774A.1, and primary mouse embryonic fibroblasts. These interactions were analyzed by confocal microscopy to determine the cytotoxicity of the strains. We also used Galleria mellonella larvae to test their pathogenicity in this experimental model. Our results demonstrated that two strains showed high cytotoxicity in epithelial cells, fibroblasts, and macrophages. Furthermore, these strains showed high virulence using the G. mellonella model. All strains used in this paper generally showed low levels of resistance to the different families of the antibiotics being tested. These results indicated that some strains of Aeromonas present in vegetables and water pose a potential health hazard, displaying very high in vitro and in vivo virulence. This pathogenic potential, and some recent concerning findings on antimicrobial resistance in Aeromonas, encourage further efforts in examining the precise significance of Aeromonas strains isolated from foods for human consumption.

Antimicrobial and the Resistances in the Environment: Ecological and Health Risks, Influencing Factors, and Mitigation Strategies

Antimicrobial contamination and antimicrobial resistance have become global environmental and health problems. A large number of antimicrobials are used in medical and animal husbandry, leading to the continuous release of residual antimicrobials into the environment. It not only causes ecological harm, but also promotes the occurrence and spread of antimicrobial resistance. The role of environmental factors in antimicrobial contamination and the spread of antimicrobial resistance is often overlooked. There are a large number of antimicrobial-resistant bacteria and antimicrobial resistance genes in human beings, which increases the likelihood that pathogenic bacteria acquire resistance, and also adds opportunities for human contact with antimicrobial-resistant pathogens. In this paper, we review the fate of antimicrobials and antimicrobial resistance in the environment, including the occurrence, spread, and impact on ecological and human health. More importantly, this review emphasizes a number of environmental factors that can exacerbate antimicrobial contamination and the spread of antimicrobial resistance. In the future, the timely removal of antimicrobials and antimicrobial resistance genes in the environment will be more effective in alleviating antimicrobial contamination and antimicrobial resistance.

Fate of Horizontal-Gene-Transfer Markers and Beta-Lactamase Genes during Thermophilic Composting of Human Excreta

Thermophilic composting is a suitable treatment for the recycling of organic wastes for agriculture. However, using human excreta as feedstock for composting raises concerns about antibiotic resistances. We analyzed samples from the start and end of a thermophilic composting trial of human excreta, together with green cuttings and straw, with and without biochar. Beta-lactamase genes bla_CTX-M, bla_IMP, and bla_TEM conferring resistance to broad-spectrum beta-lactam antibiotics, as well as horizontal gene transfer marker genes, intI1 and korB, were quantified using qPCR. We found low concentrations of the beta-lactamase genes in all samples, with non-significant mean decreases in bla_CTX-M and bla_TEM copy numbers and a mean increase in bla_IMP copy numbers. The decrease in both intI1 and korB genes from start to end of composting indicated that thermophilic composting can decrease the horizontal spread of resistance genes. Thus, thermophilic composting can be a suitable treatment for the recycling of human excreta.

Multidrug-resistant extended spectrum β-lactamase (ESBL)-producing Escherichia coli from farm produce and agricultural environments in Edo State, Nigeria

Antimicrobial resistance (AMR) is a major public health concern, especially the extended-spectrum β-lactamase-producing (ESBL) Escherichia coli bacteria are emerging as a global human health hazard. This study characterized extended-spectrum β-lactamase Escherichia coli (ESBL-E. coli) isolates from farm sources and open markets in Edo State, Nigeria. A total of 254 samples were obtained in Edo State and included representatives from agricultural farms (soil, manure, irrigation water) and vegetables from open markets, which included ready-to-eat (RTE) salads and vegetables which could potentially be consumed uncooked. Samples were culturally tested for the ESBL phenotype using ESBL selective media, and isolates were further identified and characterized via polymerase chain reaction (PCR) for β-lactamase and other antibiotic resistance determinants. ESBL E. coli strains isolated from agricultural farms included 68% (17/25) from the soil, 84% (21/25) from manure and 28% (7/25) from irrigation water and 24.4% (19/78) from vegetables. ESBL E. coli were also isolated from RTE salads at 20% (12/60) and vegetables obtained from vendors and open markets at 36.6% (15/41). A total of 64 E. coli isolates were identified using PCR. Upon further characterization, 85.9% (55/64) of the isolates were resistant to ≥ 3 and ≤ 7 antimicrobial classes, which allows for characterizing these as being multidrug-resistant. The MDR isolates from this study harboured ≥1 and ≤5 AMR determinants. The MDR isolates also harboured ≥1 and ≤3 beta-lactamase genes. Findings from this study showed that fresh vegetables and salads could be contaminated with ESBL-E. coli, particularly fresh produce from farms that use untreated water for irrigation. Appropriate measures, including improving irrigation water quality and agricultural practices, need to be implemented, and global regulatory guiding principles are crucial to ensure public health and consumer safety.

A Meta-Analysis to Estimate Prevalence of Resistance to Tetracyclines and Third Generation Cephalosporins in Enterobacteriaceae Isolated from Food Crops

Application of human and animal waste to fields and water sources and on-farm antimicrobial usage are documented contributors to the occurrence of antimicrobial resistance (AMR) in agricultural domains. This meta-analysis aimed to determine the prevalence of resistance to tetracycline (TET) and third generation cephalosporins (3GC) in Enterobacteriaceae isolated from food crops. TET was selected in view of its wide use in agriculture, whereas 3GC were selected because of the public health concerns of reported resistance to these critically important antibiotics in the environment. Forty-two studies from all six world regions published between 2010 and 2022 met the eligibility criteria. A random effects model estimated that 4.63% (95% CI: 2.57%, 7.18%; p-value: <0.0001) and 3.75% (95%CI: 2.13%, 5.74%; p-value: <0.0001) of surveyed food crops harboured Enterobacteriaceae resistant to TET and 3GC, respectively. No significant differences were observed between pre- and post-harvest stages of the value chain. 3GC resistance prevalence estimates in food crops were highest for the African region (6.59%; 95% CI: 2.41%, 12.40%; p-value: <0.0001) and lowest for Europe (1.84%; 95% CI: 0.00%, 6.02%; p-value: <0.0001). Considering the rare use of 3GC in agriculture, these results support its inclusion for AMR surveillance in food crops. Integrating food crops into One Health AMR surveillance using harmonized sampling methods could confirm trends highlighted here.