Presence of genes encoding enterotoxins in Staphylococcus aureus isolates recovered from food, food establishment surfaces and cases of foodborne diseases

Molecular characterization and antibiotic resistance of Staphylococcus aureus strains isolated from patients with diarrhea in Korea between the years 2007 and 2022

To investigate the molecular characteristics and antibiotic resistance of Staphylococcus aureus isolates from patients with diarrhea in Korea, 327 S. aureus strains were collected between 2007 and 2022. The presence of staphylococcal enterotoxin (SE) and toxic shock syndrome toxin-1 (TSST-1) genes in S. aureus isolates was determined by PCR. The highest expression of the TSST-1 gene was found in the GIMNO type (43.1% of GIMNO type). GIMNO type (Type I) refers to each staphylococcal enterotoxin (SE) gene gene (initials of genes): G = seg; I = sei; M = selm; N = seln; O = selo. Moreover, Type I isolates showed a significantly higher resistance to most antibiotics. A total of 195 GIMNO-type S. aureus strains were analyzed using multilocus sequence typing (MLST), and 18 unique sequence types (STs) were identified. The most frequent sequence type was ST72 (36.9%), followed by ST5 (22.1%) and ST30 (16.9%). Interestingly, ST72 strains showed a higher prevalence of MRSA than the other STs. In conclusion, our results were the first reported for S. aureus strains in Korea, which significantly expanded S. aureus genotype information for the surveillance of pathogenic S. aureus and may provide important epidemiological information to resolve several infectious diseases caused by S. aureus.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10068-023-01478-9.

Prevalence of staphylococcal toxin in food contaminated by Staphylococcus spp.: Protocol for a systematic review with meta-analysis

BACKGROUND

Food contamination by Staphylococcus spp. enterotoxigenic strains is quite common and despite underreporting caused by the short duration of clinical symptoms and lack of medical care, staphylococcal food poisoning is one of the most common Foodborne Diseases (FBD) in the world. This study describes a systematic review protocol with meta-analysis on the prevalence and types of staphylococcal enterotoxins in food, and the profile of contaminated foods.

METHODS

The research will be conducted through the selection of studies reporting the analysis of staphylococcal enterotoxins in food contaminated by Staphylococcus spp. Searches will happen on the following databases: Medline (OVID), GALE, Science Direct, CAB Direct (CABI), Google Scholar, in addition to manual search in the list of references of articles, directory of theses and dissertations, and countries' health agencies. Reports will be imported into the application Rayyan. Two researchers will independently select studies and extract data, and a third reviewer will solve conflicting decisions. The primary outcome will be the identification of staphylococcal enterotoxins in food, and the secondary outcomes will include staphylococcal enterotoxin types and foods involved. To assess the risk of bias in the studies, the tool developed by the Joanna Briggs Institute (JBI) will be used. For data synthesis, a meta-analysis will be performed. However, in case that is not possible, a narrative synthesis of the most relevant results will be carried out.

DISCUSSION

This protocol will serve as the basis for a systematic review that aims to relate the results of existing studies on the staphylococcal enterotoxin prevalence and types in food, and the profile of the contaminated foods. The results will broaden the perception of food safety risks, highlight existing literature gaps, contribute to the study of the epidemiological profile and may guide the allocation of health resources for the development of preventive measures related.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration number: CRD42021258223.

Prevalence and antimicrobial resistance profiling of Staphylococcus aureus isolated from traditional cheese in Yunnan, China

The prevalence of staphylococcal infection and the emergence of multidrug resistance of Staphylococcus aureus (S. aureus) are major concerns in food safety and public health. This study aimed to investigate the prevalence of S. aureus isolated from traditional Chinese Rubing and Rushan cheese, antimicrobial resistance profiles, genomic characteristics, and predict antimicrobial resistance genes (ARGs). From 124 samples, 18 of 62 (29.03%) of Rubing and 5 of 62 (8.06%) of Rushan cheese were confirmed to be S. aureus positive by standard culture-based methods. Twenty-three coagulase-positive staphylococci isolates were grouped into 16 clusters by pulsed-field gel electrophoresis and subjected to routine susceptibility testing to 12 antibiotics. Those isolates exhibited high resistance to penicillin (100%), erythromycin, trimethoprim-sulphamethoxazole (34.78%), oxacillin, clindamycin, and cefoxitin (21.74%). Multidrug-resistant (MDR) S. aureus was found in 34.78% (8 of 23) of isolates. Further, S. aureus strain DC.RB_015 isolated from Rubing cheese, recognized as the most resistant to six antibiotics, was selected for whole-genome sequencing (WGS), continued with in silico approaches. S. aureus DC.RB_015 had a single chromosome size of 2,794,578 bp and a plasmid size of 22,961 bp. The strain harbored 18 predicted ARGs, including eight efflux pump genes (mepA, tet(K), arlR, arlS, norA, mgrA, tet(38), LmrS), one peptidoglycan biosynthesis gene (bacA), two β-lactams resistance genes (mecA, blaZ), and seven genes conferring other antimicrobial resistance (APH(3')-IIIa, aad(6), ErmB, SAT-4, mecR1, GlpT, murA). The results of this study expand the knowledge of S. aureus strain DC.RB_015, increase food safety awareness, and will be helpful in establishing therapeutic therapy.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s13205-021-03072-4.

Occurrence and enterotoxin gene profiles of Staphylococcus aureus isolated from retail chicken meat

The present study was conducted to evaluate the prevalence and enterotoxin gene profiles of Staphylococcus aureus isolated from 120 chicken meat marketed in retail outlets of Chennai, India. It was observed that total of 120 meat samples collected from different retail outlets, 66.67% (80/120) of the samples were positive for the presence of S. aureus based on biochemical characterization and species specific PCR based on thermonuclease gene (nuc). Enterotoxin gene profiling of the isolates for 9 genes (sea- sej) revealed that 52.50% (42/80) of the isolates in the present study were enterotoxigenic harboring either one or more gene. It was evident that majority of the isolates harbored seb, followed by seg, sei, sec, sed and sej either alone or in combination. None of the isolates harbored sea, see and seh either alone or in combination. The results of the study clearly indicated higher prevalence of enterotoxigenic S. aureus in retail meat marketed in Chennai, India indicating the potential of retail chicken meat to act as vehicle for food borne intoxication and a major public health threat.