Bacterial content and characterization of antibiotic resistant Staphylococcus aureus in Danish sushi products and association with food inspector rankings

Methicillin-Resistant Staphylococcus aureus (MRSA) in Different Food Groups and Drinking Water

Methicillin-resistant Staphylococcus aureus (MRSA) has been included by the World Health Organization in its list of "priority pathogens" because of its widespread prevalence and the severity of the infections it causes. The role of food in infections caused by MRSA is unknown, although strains of this microorganism have been detected in various items for human consumption. In order to gain an overview of any possible role of food in MRSA infections, a review was undertaken of studies published between January 2001 and February 2024 relating to MRSA. These comprised research that focused on fish and shellfish, eggs and egg products, foods of vegetable origin, other foodstuffs (e.g., honey or edible insects), and drinking water. In most of these investigations, no prior enrichment was carried out when isolating strains. Three principal methods were used to confirm the presence of MRSA, namely amplification of the mecA gene by PCR, amplification of the mecA and the mecC genes by PCR, and disc diffusion techniques testing susceptibility to cefoxitin (30 μg) and oxacillin (1 μg). The great diversity of methods used for the determination of MRSA in foods and water makes comparison between these research works difficult. The prevalence of MRSA varied according to the food type considered, ranging between 0.0% and 100% (average 11.7 ± 20.3%) for fish and shellfish samples, between 0.0% and 11.0% (average 1.2 ± 3.5%) for egg and egg products, between 0.0% and 20.8% (average 2.5 ± 6.8%) for foods of vegetable origin, between 0.6% and 29.5% (average 28.2 ± 30.3%) for other foodstuffs, and between 0.0% and 36.7% (average 17.0 ± 14.0%) for drinking water.

Whole-genome sequencing analysis of widely disseminated infection caused by ST2631 methicillin-sensitive Staphylococcusaureus

Existing studies revealed high clonal diversity among Staphylococcus aureus bacteremia isolates, especially for methicillin-sensitive S. aureus (MSSA) strains. A 66-year-old male patient presenting with a widespread methicillin-sensitive Staphylococcus aureus (MSSA) infection, accompanied by concurrent carbapenem-resistant Klebsiella pneumoniae (CRKP) bloodstream infection.To evaluate the evolution of the present isolate, whole genome sequencing and bioinformatics analysis were performed for all available MSSA isolates. This patient recovered eventually through drainage and antibiotics combination. Therefore, the virulence factors of MSSA, as the primary pathogenicity, led to widely disseminated infection. The appropriate initial treatment is a major concern after culture identification.

Antibiotic Resistance Profiles and ARG Detection from Isolated Bacteria in a Culture-Dependent Study at the Codfish Industry Level

The antibiotic resistance phenomenon horizontally involves numerous bacteria cultured from fresh or processed seafood matrix microbiomes. In this study, the identified bacteria from food-producing processes and industrial environments were screened for phenotypic and genotypic resistance determinants. A total of 684 bacterial strains [537 from processed codfish (Gadus morhua and Gadus macrocephalus) products as salted and seasoned and soaked and 147 from environmental samples] were isolated. Antibiotic susceptibility tests showed resistance against tetracycline, oxacillin, and clindamycin in the Staphylococcus genus (both from food and environmental samples) and against beta-lactams (cefotaxime, carbapenems, etc.) and nitrofurans (nitrofurantoin) from E. coli and Salmonella enterica serovar. Enteritidis isolates. One-thousand and ten genetic determinants-tetracycline tetC (25.17%), tetK (21.06%), tetL (11.70%), clindamycin ermC (17.23%), ermB (7.60%), linezolid cfr (8.22%), optrA (3.62%), poxtA (2.05%), and oxacillin mecA (17.37%)-were amplified from Gram-positive resistant and phenotypically susceptible bacteria. Concerning Gram-negative bacteria, the beta-lactam-resistant genes (bla_TEM, bla_CIT, bla_CTX-M, bla_IMP, bla_KPC, bla_OXA-48-like) represented 57.30% of the amplified ARGs. This study found high antibiotic resistance genes in circulation in the fish food industry chain from the macro- to microenvironment. The obtained data confirmed the diffusion of the "antibiotic resistance phenomenon" and its repercussions on the One-health and food-producing systems.

Whole-Genome Analysis of Staphylococcus aureus Isolates from Ready-to-Eat Food in Russia

This study provides a thorough investigation of a diverse set of antimicrobial resistant (AMR) Staphylococcus aureus isolates collected from a broad range of ready-to-eat (RTE) food in various geographic regions of Russia ranging from Pskov to Kamchatka. Thirty-five isolates were characterized using the whole genome sequencing (WGS) analysis in terms of clonal structure, the presence of resistance and virulence determinants, as well as plasmid replicon sequences and CRISPR/Cas systems. To the best of our knowledge, this is the first WGS-based surveillance of Russian RTE food-associated S. aureus isolates. The isolates belonged to fifteen different multilocus sequence typing (MLST)-based types with a predominant being the ones of clonal complex (CC) 22. The isolates studied can pose a threat to public health since about 40% of the isolates carried at least one enterotoxin gene, and 70% of methicillin-resistant (MRSA) isolates carried a tsst1 gene encoding a toxin that may cause severe acute disease. In addition, plasmid analysis revealed some important characteristics, e.g., Rep5 and Rep20 plasmid replicons were a “signature” of MRSA CC22. By analyzing the isolates belonging to the same/single strain based on cgMLST analysis, we were able to identify the differences in their accessory genomes marking their dynamics and plasticity. This data is very important since S. aureus isolates studied and RTE food, in general, represent an important route of transmission and dissemination of multiple pathogenic determinants. We believe that the results obtained will facilitate performing epidemiological surveillance and developing protection measures against this important pathogen in community settings.

Assessment of the Microbiological Quality and Safety in Takeaway Sushi Meals in Portugal

Being a food product that contains perishable ingredients and involves a significant degree of manual handling during preparation, sushi is regarded as a potentially hazardous food, which may lead to foodborne disease outbreaks. In Portugal, consumption of takeaway sushi meals has strongly increased throughout the past few years; however, there is limited information regarding its compliance with food quality standards. Under this context, the present study aimed to evaluate the microbiological quality and safety of take-away ready-to-eat sushi meals in Lisbon, Portugal. Sixty-two samples were collected from different origins (restaurant and hypermarket), and each sample was tested for aerobic mesophilic microorganisms, Enterobacteriaceae, <i>Escherichia coli</i>, positive coagulase Staphylococci, presumptive <i>Bacillus cereus</i> count, as for detection of pathogenic microorganisms, such as <i>Salmonella</i> spp., <i>Listeria monocytogenes</i> and <i>Vibrio parahaemolyticus</i>, <i>V. cholerae</i> and <i>V. vulnificus</i>. Results revealed that 48.4% (30/62) were deemed unsatisfactory, 35.5% (22/62) were classified as borderline and only 16.1% (10/62) were considered satisfactory. Even though we did not detect the incidence of potentially pathogenic microorganisms in sushi, the presence of <i>B. cereus</i> and coagulase-positive Staphylococci was detected at unsatisfactory levels. Furthermore, significant differences between the place of origin (restaurant vs. hypermarket) and type of fish were also observed. Overall, the high number of samples classified with a level of microbiological quality “unsatisfactory” and “borderline” highlights the need to review good hygiene practices, as well as the quality of the raw materials used, to obtain a final product with a satisfactory quality and safety level.

Country Income Is Only One of the Tiles: The Global Journey of Antimicrobial Resistance among Humans, Animals, and Environment

Antimicrobial resistance (AMR) is one of the most complex global health challenges today: decades of overuse and misuse in human medicine, animal health, agriculture, and dispersion into the environment have produced the dire consequence of infections to become progressively untreatable. Infection control and prevention (IPC) procedures, the reduction of overuse, and the misuse of antimicrobials in human and veterinary medicine are the cornerstones required to prevent the spreading of resistant bacteria. Purified drinking water and strongly improved sanitation even in remote areas would prevent the pollution from inadequate treatment of industrial, residential, and farm waste, as all these situations are expanding the resistome in the environment. The One Health concept addresses the interconnected relationships between human, animal, and environmental health as a whole: several countries and international agencies have now included a One Health Approach within their action plans to address AMR. Improved antimicrobial usage, coupled with regulation and policy, as well as integrated surveillance, infection control and prevention, along with antimicrobial stewardship, sanitation, and animal husbandry should all be integrated parts of any new action plan targeted to tackle AMR on the Earth. Since AMR is found in bacteria from humans, animals, and in the environment, we briefly summarize herein the current concepts of One Health as a global challenge to enable the continued use of antibiotics.

Characterization of antimicrobial-resistant Staphylococcus aureus from retail foods in Beijing, China

Staphylococcus aureus is an opportunistic pathogen leading to food poisoning as well as human infections. The present study examined the prevalence and characterization of antimicrobial-resistant S. aureus in sushi from 42 outlets and in pork products from eight outlets in Beijing, China. The total bacterial counts were between 3.0 and 8.9 log CFU/g (mean 5.5 ± 1.5 log CFU/g) in sushi products and 4.8 to 7.4 log CFU/g (mean 5.6 ± 0.8 log CFU/g) in pork products. The mean counts of coliforms were 2.7 and 2.9 log CFU/g in sushi and pork, respectively. Staphylococcus aureus was isolated from seven sushi outlets (13 isolates) and two pork outlets (2 isolates) with average counts below 2 log CFU/g in all cases. A total of 15 S. aureus isolates were further characterized. Six lineages of S. aureus were present, including ST398 (n = 5), ST25 (n = 4), ST15 (n = 2), ST59 (n = 2), ST8 (n = 1) and ST2631 (n = 1). Thirteen isolates contained the scn virulence marker, whereas four and eight isolates contained the virulence marker edinB and enterotoxin genes, respectively. Characterization of antimicrobial resistance profiles documented resistances to ampicillin (n = 15), penicillin (n = 14), ceftazidime (n = 6), erythromycin (n = 4), tetracycline (n = 3), clindamycin (n = 3), and gentamicin (n = 1). Three MRSA isolates were obtained, one from pork (ST398) and two from one sushi outlet (ST59). They were all resistant to at least three classes of antimicrobials and two of them contained the scn gene and enterotoxin genes. Twelve sushi isolates and one of the pork isolates contained the scn gene, indicating that they were of human origin. This emphasizes the potential importance of transmission through foods of antimicrobial-resistant S. aureus including MRSA. We also showed that S. aureus exhibited geographical variation with regards to ST profiles, antimicrobial-resistance and virulence genes when comparing isolates from sushi products sold in Beijing and Copenhagen, Denmark. Whereas food safety is not compromised by the presence of low amounts of S. aureus in sushi, this study shows that with regards to public health such foods may serve as vehicles for transmission of multidrug-resistant S. aureus and MRSA lineages.

Nisin Damages the Septal Membrane and Triggers DNA Condensation in Methicillin-Resistant Staphylococcus aureus

Nisin is applied as a food preservative in processed foods and has the potential to be used synergistically with antibiotics for treatment of patients infected by antibiotic-resistant bacteria, such as methicillin-resistant Staphylococcus aureus. The present study explores the antimicrobial effect of nisin on S. aureus viability and membrane integrity and, for the first time, used super-resolution microscopy to study morphological changes induced in S. aureus cells exposed to nisin. The exposure of S. aureus to nisin caused membrane depolarization and rapid killing. Super-resolution structured-illumination microscopy and transmission electron microscopy confirmed that nisin damages the cellular membrane and causes lysis of cells. Strikingly, condensation of chromosomal DNA was observed in all cells exposed to nisin, a phenotype not previously reported for this compound. Moreover, cells exposed to nisin were significantly smaller than non-exposed cells indicating the emergence of cell shrinkage. The strong association of DNA condensation with nisin exposure indicates that nisin interferes with chromosome replication or segregation in S. aureus.

Antimicrobial Resistance and Virulence Gene Profiles of Methicillin-Resistant and -Susceptible Staphylococcus aureus From Food Products in Denmark

Foods may potentially serve as vehicles for the transmission of antimicrobial-resistant variants of Staphylococcus aureus that are important in a human clinical context. Further, retail food products can be a cause of staphylococcal food poisoning. For these reasons and to account for source attribution and risk assessment, detailed information on the population structure, resistance, and virulence profiles of S. aureus originating from retail food products is necessary. In the current study, whole-genome sequences from 88 S. aureus isolates were subjected to bioinformatics analyses in relation to sequence types, antimicrobial resistance, and virulence profiles. The sequence types (ST) identified belonged to 13 clonal complexes (CC) with CC5 and CC398 being the most common. CC398 was identified as the dominant clone (n = 31). CC5 was identified as of avian origin, with the presence of φAVβ prophage genes (n = 13). In total, 39.8% of the isolates contained multiple resistance genes, and methicillin-resistant Staphylococcus aureus (MRSA) isolates were found in CC8, CC9, and CC398. Genes conferring resistance to the antimicrobial classes of β-lactams, tetracycline, and erythromycin were detected in this study, all of which are commonly used in Danish livestock production. The tst gene encoding the toxic shock syndrome toxin was for the first time identified in ST398 isolates, probably as a result of a single acquisition of a SaPI-like element. The sushi-CC398 isolates carrying the scn gene likely originated from a human reservoir, while the other isolates originated from livestock. Taken together, our results show that both human and animal reservoirs contribute to contamination in food products and that retail foods may serve as a vehicle of S. aureus between livestock and humans.