Search Results (26)

Cronobacter spp. is a pathogenic genus comprising seven species, of which C. sakazakii is particularly notable for its association with neonatal outbreaks linked to powdered infant formula. The severity of infections is associated with virulence factors (VFs) and β-lactam antibiotic resistance genes (ARGs). Next-generation sequencing (NGS) has enabled precise strain typing through core genome multilocus sequence typing (cgMLST), enhancing discrimination and accuracy. This study aimed to use cgMLST (2831 genes) to genomically characterize 34 Cronobacter strains which had been isolated from powdered milk and production surfaces between 2011 and 2022. The identified strains included C. sakazakii ST1, ST4, ST13, ST31 and ST83, as well as C. malonaticus ST60. Overall, there were eight clusters of closely related strains. All strains exhibited resistance to cephalothin, 18 were resistant to ceftazidime and 11 to ampicillin. Various resistance genes (bla_CSA, bla_CMA, fos, qacJ, marA, AcrAB-TolC, and mcr-9.1) and virulence genes (cpa, nanAKT, fic, relB, fliC) were detected, with some genes being exclusive to C. sakazakii. All strains carried plasmids and mobile genetic elements. The multidrug resistance and presence of virulence genes in these isolates highlight the significant risk that C. sakazakii-contaminated powdered dairy products pose to public health, underscoring the need to adopt proper hygienic manufacturing practices and effectively implement HACCP in their production. Full article

This study aimed to evaluate the microbiological quality and safety of powdered formulae intended for infant consumption on the Italian market. A total of 83 samples, including 23 infant formulae (PIF), 42 follow-on formulae (FOF), and 18 formulae for special medical purposes (SMPs), were taken between 2023 and 2024. Low total viable counts were highlighted with all SMP samples, 87.0% of PIF samples and 97.6% of FOF samples being compliant with the threshold set by the Code of Hygienic Practice for Powdered Formulae for Infants and Young Children (2.70 Log CFU/g). High contamination levels (>4 Log CFU/g) were found exclusively in PIF (8.7%) and FOF samples (2.4%). Considering potential pathogenic bacteria, the presence of Listeria monocytogenes, Yersinia enterocolitica, Salmonella spp., Bacillus cereus, and Cronobacter sakazakii was investigated. Enumeration of Bacillus cereus, Staphylococcus aureus, and Clostridia was also performed. Only presumptive B. cereus was detected (37 samples, and in 3 samples was enumerated with counts equal to 1 Log CFU/g). A total of 42 presumptive B. cereus isolates were tested for the production of hemolysin BL, phosphatidylcholine-specific phospholipase C, proteases, and for the presence of chromosomal toxin-encoding genes, showing a relevant prevalence of virulence factors and highlighting a potential concern for infants. The antimicrobial resistance pattern of the isolates showed high resistance rates to β-lactams and a moderate resistance to erythromycin. A chemical–physical characterization of the formulae was also performed showing high heterogeneity in terms of pH, Aw, and concentration of organic acids. The results obtained provide useful information for monitoring the potential exposition of infants to microbial populations and to evaluate the safety of the products available on the market. Full article

The consumption of fresh fruit and vegetables is essential for a healthy diet as they contain a diverse composition of vitamins, minerals, fibre, and bioactive compounds. However, cross-contamination during harvest and post-harvest poses a high risk of microbial contamination. Therefore, handling fruit and vegetables during processing and contact with wet equipment and utensil surfaces is an ideal environment for microbial contamination and foodborne illness. Nevertheless, less attention has been paid to some emerging pathogens that are now increasingly recognised as transmissible to humans through contaminated fruit and vegetables, such as Arcobacter and Cronobacter species in various products, which are the main risk in fruit and vegetables. Cronobacter and Arcobacter spp. are recognised food-safety hazards because they pose a risk of foodborne disease, especially in vulnerable groups such as newborns and immunocompromised individuals. Cronobacter spp. have been linked to severe infant conditions—notably meningitis and sepsis—most often traced to contaminated powdered infant formula. Although Arcobacter spp. have been less extensively studied, they have also been associated with foodborne disease, chiefly from dairy products and meat. With this in mind, this review provides an overview of the main chemical and physical sanitisation methods in terms of their ability to reduce the contamination of fresh fruit and vegetable products caused by two emerging pathogens: Arcobacter and Cronobacter. Emerging chemical (organic acid compounds, extracts, and essential oils) and physical methods (combination of UV-C with electrolysed water, ultrasound, and cold atmospheric plasma) offer innovative and environmentally friendly alternatives to traditional approaches. These methods often utilise natural materials, less toxic solvents, and novel techniques, resulting in more sustainable processes compared with traditional methods that may use harsh chemicals and environmentally harmful processes. This review provides the fruit and vegetable industry with a general overview of possible decontamination alternatives to develop optimal and efficient processes that ensure food safety. Full article

Amasi, a traditional fermented milk produced in Southern Africa, is associated with several health benefits, such as probiotic activities, immune system modulation, and pharmacological (antimicrobial, antitumor and antioxidant) potential. This study investigated the microbial diversity in Amasi (produced from cow’s and goat’s milk) through targeted metagenomic bacterial 16S rRNA and fungal ITS sequencing, the metabolic functional prediction of Amasi samples using the Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) and profiled amino acids constituents using Liquid Chromatographic-Mass Spectrophotometry (LC-MS). The results obtained revealed Firmicutes, Bacteroidetes, and Proteobacteria as the most prevalent bacterial phyla, with Lactococcus and Lactobacillus being the most abundant genera. On the other hand, Ascomycota, Basidiomycota, and Mucoromycota were the main fungal phyla, while Aspergillus, Kazachstania, and Debaryomyces spp. dominated the fungal genera. Also, Pseudomonas spp., Bacillus spp., Clostridium spp., Cronobacter spp., Alternaria spp., Diaporthe spp., and Penicillium spp. were the probable pathogenic bacteria and fungi genera found, respectively. Atopobium, Synechococcus, and Parabacteroides were found less often as rare genera. It was found that the amino acid and drug metabolism pathway prediction values in Amasi samples were significantly higher (p < 0.05) than in raw cow and goat milk, according to the inferred analysis (PICRUSt). The amino acid validation revealed glutamine and asparagine values as the most significant (p < 0.05) for Amasi cow milk (ACM) and Amasi goat milk (AGM), respectively. Comparatively, ACM showed more microbial diversity than AGM, though there were relative similarities in their microbiome composition. PICRUSt analysis revealed significant metabolites in the two Amasi samples. Overall, data from this study showed heterogeneity in microbial diversity, abundance distributions, metabolites, and amino acid balance between raw cow/goat milk and Amasi samples. Full article

Cronobacter condimenti are environmental commensals that have not been associated with any clinical infections. To date, they are the least understood and described Cronobacter species within the genus. The objective of this study was to use a draft genome sequence (DGS) of the Cronobacter condimenti strain s37 to screen for genes encoding for antibiotic resistance, virulence, response to environmental stress, and biofilm formation. The strain was isolated in Poland from commercial small radish sprouts. This is the second genome of this species available in the GenBank database. The comparative genome analysis (cgMLST) of C. condimenti s37 with other Cronobacter spp. including the pathogenic species C. sakazakii and the plant-associated closely related genera Franconibacter and Siccibacter was also performed. The assembled and annotated genome of the C. condimenti s37 genome was 4,590,991 bp in length, with a total gene number of 4384, and a GC content of 55.7%. The s 37 genome encoded for genes associated with resistance to stressful environmental conditions (metal resistance genes: zinc, copper, osmotic regulation, and desiccation stress), 17 antimicrobial resistance genes encoding resistance to various classes of antibiotics and 50 genes encoding for the virulence factors. The latter were mainly genes associated with adhesion, chemotaxis, hemolysis, and biofilm formation. Cg-MLST analysis (3991 genes) revealed a greater similarity of C. condimenti s37 to S. turicensis, F. pulveris, and C. dublinensis than to other species of the genus Cronobacter. Studies on the diversity, pathogenicity, and virulence of Cronobacter species isolated from different sources are still insufficient and should certainly be continued. Especially the analysis of rare strains such as s37 is very important because it provides new information on the evolution of these bacteria. Comparative cgMLST analysis of s37 with other Cronobacter species, as well as closely related genera Franconibacter and Siccibacter, complements the knowledge on their adaptability to specific environments such as desiccation. Full article

In the context of climate change and depletion of natural resources, meeting the growing demand for animal feed and human food through sufficient, nutritious, safe, and affordable sources of protein is becoming a priority. The use of Hermetia illucens, the black soldier fly (BSF), has emerged as a strategy to enhance the circularity of the agri-food chain, but its microbiological safety remains a concern. The aim of the present study was to systematically review available data on the microbiological quality of BSF and to investigate the impact of using four different rearing substrates including classic options allowed by the EU regulation (cereals, fruits, vegetables) and options not allowed by EU regulations regarding vegetable agri-food (co-products, food at shelf life, and meat). A total of 13 studies were collected and synthesized, including 910 sample results, while 102 new sample results were collected from the present experiments in three farms. Both datasets combined revealed a high level of contamination of larvae, potentially transmitted through the substrate. The main pathogenic bacteria identified were Bacillus cereus, Clostridium perfringens, Cronobacter spp., Escherichia coli, Salmonella spp., and Staphylococcus aureus coagulase-positive, while Campylobacter spp. and Listeria monocytogenes were not detected. Any of these four substrates were excluded for their use in insect rearing; however, safety concerns were confirmed and must be managed by the operators of the sector using microbial inactivation treatment after the harvest of the larvae in order to propose safe products for the market. The results obtained will guide the definition of the control criteria and optimize the following manufacturing steps. Full article

Cronobacter spp. are the most concerning foodborne pathogen in infant formula milk powder. Currently, there are many reports on the prevalence of Cronobacter spp. in infant formula milk and its processing environment, but there are few studies on the prevalence of Cronobacter spp. on dairy farms. We have, therefore, undertaken this study to investigate and track genomic epidemiology of Cronobacter spp. isolates from Chinese dairy farms in the provinces of Jiangsu and Shandong. In this study, forty Cronobacter spp. strains, consisting of thirty Cronobacter sakazakii, eight Cronobacter malonaticus, and two Cronobacter dublinensis, were obtained from 1115 dairy farm samples (raw milk, silage, bedding, and feces), with a prevalence rate of 3.57%. These isolates were classified into 10 Cronobacter serotypes and 31 sequence types (STs), including three novel STs which were isolated for the first time. Notably, pathogenic Cronobacter STs 7, 8, 17, 60, and 64, which are associated with clinical infections, were observed. Antimicrobial susceptibility testing showed that all the Cronobacter spp. were highly resistant to cephalothin and fosfomycin, which was consistent with the antimicrobial genotype. All isolates carried core virulence genes related to adherence, invasion, endotoxin, immune evasion, secretion system, and regulation. Approximately half the isolates were also able to produce a strong biofilm. Twenty-one prophages and eight plasmids were detected, with the most common prophage being Cronobacter_ENT47670 and the most common plasmid being IncFIB (pCTU1). In addition, two isolates harbored the transmissible locus of stress tolerance (tLST) which confers high environmental persistence. Phylogenetic analysis showed strong clustering by species level and sequence types. Isolates from different sources or regions with a similar genomic background suggests the cross-contamination of Cronobacter spp. The presence of diverse genotypes of Cronobacter spp. in dairy farms in Jiangsu and Shandong provinces indicates that surveillance of Cronobacter spp. on dairy farms should be strengthened, to prevent and control transmission and ensure the quality and safety of raw dairy products. Full article

The objective of this study was to characterize Cronobacter spp. and related organisms isolated from powder dairy products intended for consumption by adults and older adults using whole-genome sequencing (WGS), and to identify genes and traits that encode antibiotic resistance and virulence. Virulence (VGs) and antibiotic resistance genes (ARGs) were detected with the Comprehensive Antibiotic Resistance Database (CARD) platform, ResFinder, and MOB-suite tools. Susceptibility testing was performed using disk diffusion. Five presumptive strains of Cronobacter spp. were identified by MALDI–TOF MS and ribosomal MLST. Three C. sakazakii strains were of the clinical pathovar ST1, one was ST31, and the remaining isolate was C. malonaticus ST60. In addition, Franconibacter helveticus ST345 was identified. The C. sakazakii ST1 strains were further distinguished using core genome MLST based on 2831 loci. Moreover, 100% of the strains were resistant to cefalotin, 75% to ampicillin, and 50% to amikacin. The C. sakazakii ST1 strains were multiresistant (MDR) to four antibiotics. Additionally, all the strains adhered to the N1E-115 cell line, and two invaded it. Eighteen ARGs mainly involved in antibiotic target alteration and antibiotic efflux were detected. Thirty VGs were detected and clustered as flagellar proteins, outer membrane proteins, chemotaxis, hemolysins, and genes involved in metabolism and stress. The pESA3, pSP291-1, and pCMA1 plasmids were detected, and the prevalent mobile genetic elements (MGEs) were ISEsa1, ISEc52, and IS26. The isolates of C. sakazakii and C. malonaticus exhibited multiresistance to antibiotics, harbored genes encoding various antibiotic resistance proteins, and various virulence factors. Consequently, these contaminated powdered dairy products pose a risk to the health of hypersensitive adults. Full article

The present study aimed to determine the genotyping diversity and hemolytic properties of 24 strains of Cronobacter spp. (15 Cronobacter sakazakii, 6 Cronobacter malonaticus, 2 Cronobacter turicensis, and 1 Cronobacter condimenti) isolated from commercial ready-to-eat leaf vegetables, sprouts, nuts, and dried fruits. The multilocus sequence typing (MLST) method was used to determine the sequence types (ST) and clonal complexes (CC) of these strains. The study demonstrated the high genotypic diversity of the Cronobacter genus bacteria isolated from plant-based foods. Five novel sequence types (804, 805, 806, 807, and 808) and the presence of novel alleles in the ppsA, gltB, gyrB, and infB loci were detected. In total, 16 of the 24 strains were assigned to the sequence types ST99, ST258, ST17, ST648, ST21, ST494, and ST98. One C. sakazakii strain (s12) isolated from alfalfa sprouts was assigned to the clonal complex CC4, which encompasses strains often associated with severe infections leading to meningitis in infants. In addition, 87.5% and 16.7% of the Cronobacter spp. strains showed β-hemolysis of equine and sheep red blood cells, respectively. The presence of the pathogenic species C. sakazakii, C. malonaticus, and C. turicensis in ready-to-eat plant-derived food products shows they are potential sources of infection, especially to those with compromised immunity, which substantiates their further multi-faceted characterization. The significance of this study may prove useful not only in epidemiological investigations, but also in assessing the risk of infections caused by the presence of Cronobacter. Full article

Background: This study aimed to investigate the prevalences of some important antibiotic-resistance genes (ARGs) and foodborne bacterial pathogens in sweet samples collected from local markets in Iran. Methods: Forty sweet samples were collected. Foodborne pathogens and ARGs were detected in the sweet samples by conventional and multiplex PCR assays using species-specific primers. Results: Staphylococcus aureus, Cronobacter sakazakii, Shigella spp., Campylobacter jejuni, and Campylobacter coli were detected and identified in 47.5%, 20%, 45%, 5%, and 30% of the sweet samples, respectively. We found S. aureus and Shigella spp. were the most prevalent bacterial pathogens. S. aureus was found to be the most frequent pathogenic bacteria profiled in these samples. We also found a significant correlation between the presence of C. coli and Cr. sakazakii. We detected the bla_SHV resistance gene in 97.5% of the sweet samples; however, bla_TEM was detected in only one sample (2.5%). Conclusions: Regarding these results, we suggest preventive strategies such as implementing automation of food processing; monitoring the personal hygiene and health of food handlers, and testing regularly for antibiotic resistance in raw materials and products. Full article

Introduction: The involvement of bacteria in the pathogenesis of biliary tract disease is largely unknown. In this study, we investigated the microbiota of the biliary tissue among adult patients with choledocholithiasis during endoscopic retrograde cholangiography (ERCP). Methods: 16S rDNA sequencing of bile samples, culture, and data of the medication history, underlying diseases, and liver function tests were used for the interpretation of differences in the composition of detected bacterial taxa. Results: The four most common phyla in the bile samples included Proteobacteria, Firmicutes, Actinobacteria, and Bacteroidetes. Infection with anaerobic and microaerophilic bacteria showed host specificity, where Fusobacterium, Prevotella, Veillonella, Propionibacterium, Gemella, and Helicobacter coexist in the same patients. Clostridium and Peptoclostridium spp. were detected in 80% and 86% of the patients, where the highest relative abundance rates were detected in patients with elevated alkaline phosphatase (ALP) levels and leukocytosis, respectively. Higher diversity in the bacterial population was detected in patients with common bile duct (CBD) stone, in which the richness of an unclassified member of Alphaproteobacteria plus Helicobacter, Enterobacter/Cronobacter spp., Sphingomonas, Prevotella, Fusobacterium and Aeromonas were detected. Conclusions: Our findings suggested correlations between the presence and relative abundance of several bacterial taxa and CBD stone formation and the effect of medication and underlying diseases on the bile microbial communities. A study on a higher number of bile samples from patients compared with the control group could reveal the role of these bacteria in the pathogenesis of biliary tract disease. Full article

Cronobacter spp. are emerging foodborne pathogens that cause severe diseases. However, information on Cronobacter contamination in quick-frozen foods in China is limited. Therefore, we studied the prevalence, molecular characterization, and antimicrobial susceptibility of Cronobacter in 576 quick-frozen food samples collected from 39 cities in China. Cronobacter spp. were found in 18.75% (108/576) of the samples, and the contamination degree of the total positive samples was 5.82 MPN/g. The contamination level of frozen flour product samples was high (44.34%). Among 154 isolates, 109 were C. sakazakii, and the main serotype was C. sakazakii O1 (44/154). Additionally, 11 serotypes existed among four species. Eighty-five sequence types (STs), including 22 novel ones, were assigned, indicating a relatively high genetic diversity of the Cronobacter in this food type. Pathogenic ST148, ST7, and ST1 were the main STs in this study. ST4, epidemiologically related to neonatal meningitis, was also identified. All strains were sensitive to cefepime, tobramycin, ciprofloxacin, and imipenem, in which the resistance to cephalothin was the highest (64.94%).Two isolates exhibited multidrug resistance to five and seven antimicrobial agents, respectively. In conclusion, these findings suggest that the comparatively high contamination level of Cronobacter spp. in quick-frozen foods is a potential risk warranting public attention. Full article

Antibiotic resistance (AR) and multidrug resistance (MDR) have been confirmed for all major foodborne pathogens: Campylobacter spp., Salmonella spp., Escherichia coli and Listeria monocytogenes. Of great concern to scientists and physicians are also reports of antibiotic-resistant emerging food pathogens—microorganisms that have not previously been linked to food contamination or were considered epidemiologically insignificant. Since the properties of foodborne pathogens are not always sufficiently recognized, the consequences of the infections are often not easily predictable, and the control of their activity is difficult. The bacteria most commonly identified as emerging foodborne pathogens include Aliarcobacter spp., Aeromonas spp., Cronobacter spp., Vibrio spp., Clostridioides difficile, Escherichia coli, Mycobacterium paratuberculosis, Salmonella enterica, Streptocccus suis, Campylobacter jejuni, Helicobacter pylori, Listeria monocytogenes and Yersinia enterocolitica. The results of our analysis confirm antibiotic resistance and multidrug resistance among the mentioned species. Among the antibiotics whose effectiveness is steadily declining due to expanding resistance among bacteria isolated from food are β-lactams, sulfonamides, tetracyclines and fluoroquinolones. Continuous and thorough monitoring of strains isolated from food is necessary to characterize the existing mechanisms of resistance. In our opinion, this review shows the scale of the problem of microbes related to health, which should not be underestimated. Full article

The objective of this study was to use whole-genome sequencing (WGS) to screen for genes encoding for antibiotic resistance, fitness and virulence in Cronobacter sakazakii strains that had been isolated from food and powdered-milk-producing environments. Virulence (VGs) and antibiotic-resistance genes (ARGs) were detected with the Comprehensive Antibiotic Resistance Database (CARD) platform, ResFinder and PlasmidFinder tools. Susceptibility testing was performed using disk diffusion. Fifteen presumptive strains of Cronobacter spp. were identified by MALDI-TOF MS and ribosomal-MLST. Nine C. sakazakii strains were found in the meningitic pathovar ST4: two were ST83 and one was ST1. The C. sakazakii ST4 strains were further distinguished using core genome MLST based on 3678 loci. Almost all (93%) strains were resistant to cephalotin and 33% were resistant to ampicillin. In addition, 20 ARGs, mainly involved in regulatory and efflux antibiotics, were detected. Ninety-nine VGs were detected that encoded for OmpA, siderophores and genes involved in metabolism and stress. The IncFIB (pCTU3) plasmid was detected, and the prevalent mobile genetic elements (MGEs) were ISEsa1, ISEc52 and ISEhe3. The C. sakazakii isolates analyzed in this study harbored ARGs and VGs, which could have contributed to their persistence in powdered-milk-producing environments, and increase the risk of infection in susceptible population groups. Full article

Cronobacter spp. is a food-borne pathogenic microorganism that can cause serious diseases such as meningitis, sepsis, and necrotizing colitis in infants and young children. Powdered infant formula (PIF) is one of the main contamination routes, in which the processing environment is an important source of pollution. In this investigation, 35 Cronobacter strains isolated from PIF and its processing environment were identified and typed by 16S rRNA sequencing and multilocus sequence typing (MLST) technology. A total of 35 sequence types were obtained, and three new sequence types were isolated for the first time. The antibiotic resistance was analyzed, showing that all isolates were resistant to erythromycin but sensitive to ciprofloxacin. Multi-drug resistant strains accounted for 68.57% of the total, among which Cronobacter strains with the strongest drug resistance reached 13 multiple drug resistance. Combined with transcriptomics, 77 differentially expressed genes related to drug resistance were identified. The metabolic pathways were deeply excavated, and under the stimulation of antibiotic conditions, Cronobacter strains can activate the multidrug efflux system by regulating the expression of chemotaxis-related genes, thus, secreting more drug efflux proteins to enhance drug resistance. The study of drug resistance of Cronobacter and its mechanism has important public health significance for the rational selection of existing antibacterial drugs, the development of new antibacterial drugs to reduce the occurrence of bacterial resistance, and the control and treatment of infections caused by Cronobacter. Full article