Methicillin-resistant Staphylococcus Aureus In Food Research Articles

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.

The role of food in the spread of the Methicillin – resistant Staphylococcus aureus (MRSA)

Methicillin-resistant Staphylococcus aureus (MRSA) are important human pathogen. It is present in a wide range of animal species (pigs, cows, sheep, and chickens) even in healthy animals. Identification of MRSA in foods has led to concerns about the role of livestock in the epidemiology of MRSA infections in human. This review focuses on the spread of MRSA in different types of food and its antimicrobial resistance to the most widely used antimicrobials in human and veterinary medicine. The results of review indicates that livestock is major source of MRSA in humans and mainly transmitted to humans through contaminated food. The actual prevalence of MRSA in animals and food as well as impact to the human health is not well understood. It is clearly that MRSA is an important pathogen to veterinary medicine and human health which requires more and in-depth research to understand the hazard and take effective measures to limit it.

Role of milk and milk products in the spread of methicillin-resistant Staphylococcus aureus in the dairy production chain.

Milk and milk products can harbor a multiple varieties of microorganisms. Therefore, they can be an important source of foodborne pathogens, including multidrug-resistant bacteria. Methicillin-resistant Staphylococcus aureus (MRSA) causes a wide spectrum of infections both in animals and humans. Over the last two decades, the presence of MRSA in foods and food-producing animals, including milk and milk products, has been frequently reported worldwide, raising public health concerns. In order to monitor and prevent foodborne MRSA contamination, it is necessary to understand their sources, the pheno/genotypic characteristics of the strains, and their transmission dynamics. In this review, studies conducted worldwide were summarized in order to assess the prevalence and diversity of MRSA circulating in milk and milk products. The risk factors for the occurrence of MRSA in milk and milk products were also discussed with preventive and control measures to avoid MRSA contamination in the dairy food chain.

Young astringent persimmon tannin inhibits methicillin-resistant Staphylococcus aureus isolated from pork

Persimmon tannin (PT), a primary physiological component of young persimmon, exhibits antibacterial activity against several microorganisms, but its effect on methicillin-resistant Staphylococcus aureus (MRSA) remains unclear. In this study, we found that PT from young astringent persimmon fruit had an active inhibition against several MRSA isolated from retail pork and the minimum inhibitory concentrations were 1000 μg/mL. Treatment of PT suppressed cell proliferation, caused decreases in membrane potential and intracellular ATP concentration, destroyed whole cell protein integrity, and induced S phase cell cycle arrest. Electron microscopy demonstrated that PT can change the normal morphology of MRSA and cause severe damage on cell wall and cell membrane. These results indicated that PT presented antimicrobial activity against foodborne MRSA and could be potentially developed as an alternative or supplemental agent to control the spread and infection of MRSA in foods.

Prevalence, Molecular Characterization, and Antimicrobial Susceptibility of Methicillin-Resistant Staphylococcus aureus from Different Origins in Sichuan Province, China, 2007-2015.

Methicillin-resistant Staphylococcus aureus (MRSA) is a major multidrug-resistant (MDR) opportunistic pathogen that is responsible for nosocomial infections worldwide. The emergence of MRSA in food-producing animals has heightened concerns regarding the presence of MRSA in foods having an animal origin. The objectives of this study were to determine the prevalence of MRSA in different sources, including retail food, food-producing animals, and food handlers in Sichuan province. During 2007-2015, S. aureus was isolated from samples having different origins. Susceptibilities of MRSA to a panel of 12 antimicrobial agents were determined according to Clinical and Laboratory Standards Institute (CSLI) procedures. Pulsed-field gel electrophoresis, spa typing, staphylococcal chromosomal cassette (SCC) mec typing, and multilocus sequence typing (MLST) were used to characterize the relationship between these isolates. A total of 756 S. aureus were isolated from 11,067 samples. Of these, 52 isolates were classified as MRSA based on the presence of mecA genes. An antimicrobial susceptibility assay indicated that CHL-CLI-ERY-FOX-OXA-PEN-TET (n = 10) and CHL-CIP-CLI-ERY-FOX-OXA-PEN-TET (n = 8) were the two predominant MDR profiles in the isolates. Using 60% genetic similarity as a cutoff, the 52 MRSA isolates were grouped into 6 clusters having 34 pulsotypes. MLST typing showed seven multilocus sequence types (STs) with ST59 and ST9 being the most common. Six SCCmec types were identified in all MRSA isolates. The MRSA isolates had relatively low prevalence in Sichuan province. Clonal expansion is not involved in the dissemination of MRSA from food origins. Considering the threat of MRSA to public health, further surveillance is required to monitor the prevalence of food-related MRSA.

Genotyping of methicillin-resistant Staphylococcus aureus (MRSA) isolated from milk and dairy products in South Italy

Methicillin-resistant Staphylococcus aureus (MRSA) is a pathogen emerging in hospitals as well as community and livestock. MRSA is a significant and costly public health concern because it may enter the human food chain and contaminate milk and dairy products causing foodborne illness.This study aimed to determine the occurrence and the characteristics of MRSA isolated from 3760 samples of milk and dairy products in a previous survey conducted in southern Italy during 2008–2014. Overall out of 484 S. aureus strains isolated, 40 (8.3%) were MRSA and were characterized by spa-typing, Multi-Locus Sequence Typing, SCCmec typing, Staphylococcal enterotoxins (SEs) genes, Panton-Valentine Leukocidin (PVL) genes and ability to form biofilm.The most frequently recovered STs were ST152 (t355–67.5%), followed by ST398 (t899, t108–25%), ST1 (t127–5%) and ST5 (t688–2.5%). All isolates harboured the SCCmec type V (92.5%) or IVa (25%). In one isolate (2.5%), ST398/t899, the SCCmec resulted not detected. Three isolates (7.5%) carried one or more enterotoxin encoding genes (one strain had seg, sei, sem, sen and seo genes; two strains had seh gene). The 50% of isolated strains harboured PVL-encoding genes. Molecular analysis for icaA and icaD genes showed: 72.5% icaA and icaD positive, 25% only icaD gene and one icaA and icaD negative. The detection of MRSA in food of animal origin is a potential health hazard, thus it is necessary monitoring of food-producing animals and improving hygiene standards in food practices in order to reduce the microbiological risk to minimum.

Methicillin resistance in Staphylococcus aureus strains isolated from food and wild animal carcasses in Italy

Following the detection of methicillin-resistant Staphylococcus aureus (MRSA) ST398 in food-producing animals, both livestock and wildlife, and derived products, are considered potential sources of MRSA in humans. There is a paucity of data on MRSA in foods in Italy, and the data regarding wild animals are particularly scarce. A total of 2162 food samples collected during official monitoring activities in 2008 were analyzed for the detection of S. aureus. Also, samples from 1365 wild animals collected by the National Reference Center for Wild Animal Diseases in 2003–2009 were subjected to anatomopathological examination. S. aureus isolates were processed for phenotypic and molecular methicillin resistance determinations.S. aureus was found in 2.0% of wild animal carcasses and in 3.2% of wild boar lymph nodes: none showed methicillin resistance. The prevalence of S. aureus in food was 17.1%. Two MRSA strains, both from bulk tank milk (prevalence 0.77%) were isolated: the strains were resistant to tetracycline, had spa-type t899, and were negative for the Panton-Valentine leukocidin gene. The low prevalence of MRSA suggests that the risk of transmission to humans via food is limited. However, attention should be paid to the cattle food chain, which may be a potential route of transmission of LA-MRSA.

Optimization of Nanoporus Anodic Aluminum Sensor-Based Lspr for Methicillin-Resistant Staphylococcus Aureus detection

Methicillin-resistant Staphylococcus aureus (MRSA) causes foodborne illnesses in approximately 241,000 persons in the United States annually, despite of greatly underreported (about 25 fold) and underdiagnosed (about 29 fold) ratio. MRSA has considered as one of the major foodborne pathogens, and it is considered as one of the most significant threats to public health. Recently, MRSA has gained substantial attention due to its increasing resistance against a broad range of antibiotics. The timely detection and quantification of MRSA are of key importance for the prevention of MRSA outbreaks. Considerable efforts have been directed towards the development of rapid and practical biosensor methods for MRSA detection. To keep up this trend, SPR method has been combined with a nanoporous anodic aluminum (NAA) sensor in this study, which is called as NAA sensor -based localized surface plasmon resonance (LSPR) system (Figure 1). This method will overcome the limitations of SPR method due to larger surface-to-volume ratio of NAA sensor. This study aims to optimize the pore size of NAA prior to employment of the NAA-based LSPR system for MRSA detection. For the fabrication of three different sizes of NAA sensor, a two-step anodizing method was employed using various anodization voltage and time, and electrolyte solution. The topology of NAA sensors were observed by employing FE-SEM for measuring the pore diameter, inter-pore distance, and pore length. The reflectance spectrum and fringe pattern of each NAA sensor were measured by using LSPR for the selection of optimum NAA sensor for MRSA detection. The NAA sensor was modified with 11-mercaptoundecanoic acid and immobilized with anti-S. aureus polyclonal antibody. The NAA immunosensors were then exposed to serially diluted MRSA culture starting from 101 CFU/mL to 108 CFU/mL for the measurement of wavelength shift. The attachment of MRSA on the surface of NAA immunosensor was confirmed by SEM observation. Three different pore sizes of sensors were successfully fabricated in the range of 50 to 200 nm by the modification of fabrication conditions. The inter-pore distance and pore length of each sensor with different pore size were 99.7 ± 4.13 nm and 1.02 ± 0.01 µm for 50 nm size sensor, 201.5 ± 2.12 nm and 1.01 ± 0.01 µm for 100 nm size sensor, and 260 ± 1.40 nm and 1.00 ± 0.01 µm for 200 nm size sensor, respectively. The reflectance spectrum and fringe pattern of 200 nm size of sensor showed clearer and greater reflectance spectrum than those of 50 nm and 100 nm pore size of sensor. In addition, the sensitivity of 50, 100 and 200 nm pore size of NAA sensors were determined to be 747 nm/RIU, 1000 nm/RIU, and 1534 nm/RIU, respectively. The wavelength shift of MRSA on the NAA immunosensor was increased as the concentration of MRSA increased. The confirmed numbers of MRSA captured on the NAA immunosensor were increased in a concentration-dependent manner. Detection limit of NAA-based LSPR method was determined to be 102 ± 0.79 CFU/mL. Taking the excellent advantage in cost-effectiveness and simple fabrication of NAA sensor, an optimized NAA sensor-based LSPR method could be applied to detect MRSA in food with successful practicability. Figure 1

Food handlers: a bridge in the journey of enterotoxigenic MRSA in food

We investigated the presence of enterotoxigenic and methicillin-resistant Staphylococcus aureus (MRSA) in a kitchen of a catering firm by collecting 100 food samples and 100 utensil-equipment samples after sanitation. Additional 186 samples in total were collected by swabbing the mouths, noses and hands of 62 kitchen staff members during working hours. The isolation of S. aureus was performed using a culture method and verified by using a genetic method (PCR). The presence of toxin genes and the toxic shock syndrome gene (tst) was analyzed by PCR. ELISA was used to investigate whether the isolates bearing a toxin gene that produces enterotoxin or not. In this research we obtained 1930 isolates from 386 samples. Using molecular typing by PCR, 842 Staphylococcus spp. were found of which 307 (36.4 %) were identified as S. aureus. 198 (64.4 %) of the S. aureus strains were identified as CoA positive and 89 (28.9 %) as MRSA. Our data demonstrate the presence of MRSA and enterotoxigenic S. aureus in a catering kitchen providing daycare and hospital refectories. Given the facts that the rate of kitchen staff members contaminated with enterotoxigenic strains was rather high and that the kitchen contained S. aureus even after sanitation and that there was uneducated staff and insufficient hygiene practices aroused suspicions of the presence of biofilms and/or multi-resistant strains which could manifest a serious public health concern.

Foods from black market at EU border as a neglected route of potential methicillin-resistant Staphylococcus aureus transmission

The illegal entrance of foods to EU through black markets at the EU borders can constitute a neglected route of dissemination of foodborne pathogens, and in particular of methicillin-resistant Staphylococcus aureus (MRSA). In this study, we have assessed the presence of MRSA in foods sold in a black market at an EU border (the southeast part of Romania, on the border with Republic of Moldavia). We performed a search for MRSA among 200 food samples collected from 2012 to 2013. All S. aureus were studied by pulsed-field gel electrophoresis (PFGE) and antimicrobial susceptibility testing. MRSA isolates were further characterized by multilocus sequence typing (MLST) and SCCmec typing, and tested for the presence of Panton–Valentine leukocidin (PVL) virulence factors. Overall, 32 S. aureus isolates were recovered from 16 food samples (8%). One isolate detected in a pork lard sample was MRSA (0.5%). PFGE with the restriction enzyme SmaI revealed 12 genotypes among the 32 S. aureus isolates. The MRSA isolate belonged to sequence type 398, harbored SCCmec type V, tested negative for the presence of the PVL genes and was resistant to ciprofloxacin, tetracycline and cefazolin, besides all β-lactams. Among 31 methicillin-sensitive S. aureus (MSSA), 29% were resistant to penicillin, 9.7% to tetracycline and 3.2% to ciprofloxacin. In conclusion, in this study we report the presence of livestock-associated MRSA in foods sold in a black market at an EU border: ST398-MRSA-V. These results confirm the potential role of food in the dissemination of MRSA lineages among population, and the potential role of illegally introduced food to EU in the prevalence and evolution of MRSA clones in the community.

Foods confiscated from non-EU flights as a neglected route of potential methicillin-resistant Staphylococcus aureus transmission

The emergence of methicillin-resistant Staphylococcus aureus (MRSA) in food-producing animals has provoked a great concern in the presence of MRSA in associated foodstuff. In this study, we have assessed for the first time the presence of MRSA in food confiscated from non-EU flights. We performed a search for MRSA among 195 food samples confiscated from passengers on flights from twenty-one non-EU countries in 2012 and 2013. One hundred and seventeen meat samples of diverse animal origin (including antelope, beef, chicken, duck, guinea pig, pork, rodents, and turkey), 75 dairy products (74 cheeses and 1 butter) and 3 eggs were analyzed. All S. aureus were studied by pulsed-field gel electrophoresis (PFGE) and antimicrobial susceptibility testing. MRSA isolates were further characterized by multilocus sequence typing (MLST), SCCmec typing, and tested for the presence of Panton–Valentine leukocidin (PVL) virulence factors. Overall, 66 food samples were positive for S. aureus (33.9%). Six S. aureus strains were MRSA (9.1%), all of them in flights from Bolivia (and 5 from the same passenger). Among methicillin-sensitive S. aureus (MSSA) (60 out of 66S. aureus strains), 44.1% were resistant to penicillin, 10.2% to tetracycline, 8.5% were resistant to aminoglycosides (amikacin and tobramycin) and 3.4% exhibited the M phenotype. MRSA isolates were sensitive to all non-β-lactam antibiotics tested. SmaI-PFGE analysis provided 40 genotypes among the S. aureus isolates (three genotypes among the six MRSA). Five MRSA isolates belonged to ST8 and harboured SCCmec type IVc as well as PVL genes. One isolate belonged to ST1649, harboured SCCmec type IVc and tested negative for the presence of the PVL genes. In conclusion, in this study, we report for the first time the presence of CA-MRSA in food confiscated from non-EU flights: ST8/ST1649-MRSA-IV. These results confirm the illegal entrance of food as a neglected route of transmission as well as the dissemination of successful CA-MRSA lineages among countries via illegal foods. As a result, illegally imported food could play a role in the prevalence and evolution of MRSA clones in the community.

Antimicrobial Susceptibility and Molecular Typing of Methicillin-ResistantStaphylococcus aureusin Retail Foods in Shaanxi, China

The aims of this study were to evaluate the occurrence of methicillin-resistant Staphylococcus aureus (MRSA) in retail foods in Shaanxi, China and to investigate antimicrobial resistance and molecular characteristics of these strains. A total of 1979 retail food samples were randomly collected during 2008-2012 from supermarkets and farmers markets and screened for S. aureus, and then S. aureus isolates were further examined to determine whether they were MRSA. MRSA isolates were further characterized by antimicrobial susceptibility test, pulsed-field gel electrophoresis, spa typing, multilocus sequence typing, and SCCmec typing, and were examined for genes encoding enterotoxins, exfoliative toxins, Panton-Valentine leukocidin (pvl), and toxic shock syndrome toxin 1. Among all the samples examined, four (1.4%) raw milk samples, six (2.3%) chicken samples, one (0.6%) pork sample, three (0.6%) ready-to-eat food samples, and three (2.5%) dumpling samples were positive for MRSA. No MRSA isolates were recovered from infant foods. A total of 23 MRSA isolates were recovered from the 17 MRSA-positive samples. Antimicrobial susceptibility tests showed that, among these MRSA isolates, resistance was most frequently observed to penicillin, ampicillin, oxacillin, cefoxitin, and clindamycin (each 100%), followed by erythromycin (95.7%) and clarithromycin (87.0%). The commonly detected toxin genes were pvl, seg, seb, sed, followed by see, sec, and sei. Seven spa types (t189, t377, t437, t899, t10793, t5762, and a new spa type) and three SCCmec types (II, IVb, and V) were identified. More than half (52.2%) of the MRSA isolates belonged to ST9, followed by ST88, ST59, ST188, ST72, and ST630. Our findings indicate that MRSA in food could be from both animal and human origin. Although the prevalence is low, the presence of multidrug resistant and enterotoxigenic MRSA strains in foods poses a potential threat to consumers and emphasizes the need for better control of sources of contamination.

Staphylococcus aureus resistente à meticilina (MRSA) em alimentos de origem animal: uma revisão sistemática

Methicillin-resistant Staphylococcus aureus (MRSA) is a major cause of infections in humans and onset of this bacterium in hospitalized individuals has been well documented. However, a report on MRSA colonization and infection of individuals in the community, without prior contact with hospital environment, suggests the occurrence of other sources of contamination, such as the use of drugs in livestock, causing colonization of production animals with MRSA, and resulting in contamination of meat products. This study aimed at compiling and analyzing the scientific publications on the occurrence of MRSA in foods. A systematic review of the literature was performed in Lilacs, Medline and Pubmed databases, and the articles published from 2000 to 2013 were selected. A significant number of studies involving different samples was observed. Wide variations on the MRSA prevalence were found, and also on the methodologies used for the analyses. The MLST strain ST398 is commonly detected in pigs, and it was the most isolated bacterium from samples analyzed in different studies. ST8 and ST5 strains, belonging to human biovar, have also been frfrequently isolated, suggesting that food handlers have been a source for meat contamination with MRSA.

Methicillin-resistant Staphylococcus aureus (MRSA) Isolated from Colombian Foods

Methicillin-resistant Staphylococcus aureus (MRSA) was identified as a nosocomial pathogen in the 1960s and it is associated with serious community-acquired and nosocomial diseases, particularly in immunocompromised patients. S. aureus also causes food poisoning and is the most important food-borne disease in Latin America. In Colombia, the Community acquired (CA-MRSA) increased by 4.4% between 2001 and 2006. However, the transmission of MRSA through food has not been well researched; its prevalence is unknown as is the risk of consumer exposure. It is important to determine the role of food in transmission of antibiotic-resistant bacteria, taking into account that the prevalence of MRSA varies according to geographical location. The aim of this study was to determine the prevalence of MRSA in Colombian foods and to typify isolated strains by detecting antimicrobial resistance, clonal groups and Toxin A gene. Resistance of 149 S. aureus strains isolated from food was determined by disk diffusion with oxacillin (1μg) and cefoxitin (30μg), Antimicrobial Susceptibility Test (AST) and mecA gene amplification. Positive strains were genotyped using pulsed field electrophoresis (PFGE). 5 (3.35%) of the 149 strains resistant to oxacillin and cefoxitin, were positive to mecA gene, indicating the presence of the SCC cassette. The electrophoretic pattern obtained by PFGE for these strains revealed that 4 (80%) of the 5 strains belong to the Chilean clone, with 100% genetic similarity; this clone has been associated with 65% of infections associated with health care. Furthermore, none of the 5 strains were positive to Toxin A gene. This is the first evidence of the presence of MRSA in food in Colombia. It is necessary to continue this research by extending the sampling and collecting enough information to carry out risk analysis of the danger.

Prevalence of methicillin-resistant Staphylococcus aureus in meat

Recently the isolation of methicillin-resistant Staphylococcus aureus (MRSA) strains from several food-producing animals has been reported. During slaughtering of MRSA-positive animals, contamination of carcasses with MRSA may occur and consequently the meat of these animals may get contaminated. The aim of this study was to estimate the prevalence of MRSA in raw meat samples from the retail trade. Samples of raw beef, pork, veal, lamb/mutton, chicken, turkey, fowl and game were collected from the retail trade. A detection method including a two-step enrichment in Mueller–Hinton broth + 6.5% NaCl and phenol red mannitol broth containing ceftizoxime and aztreonam, followed by isolation on MRSA ID agar (bioMérieux) was evaluated and subsequently applied for the detection of MRSA in samples of raw meats. MRSA strains were isolated from 264 (11.9%) of 2217 samples analyzed. Isolation percentages for the meat species were: beef (10.6%), veal (15.2%), lamb and mutton (6.2%), pork (10.7%), chicken (16.0%), turkey (35.3%), fowl (3.4%) and game (2.2%). The majority (85%) of the isolated strains belonged to spa-types of pulsed-field gel electrophoresis (PFGE) non-typeable (NT)-MRSA, corresponding to the multilocus sequence type ST398, a type also recently isolated in the Netherlands from pigs. However, a smaller part of these strains were found to be of other ST's, possibly of human origin. Further studies are needed to elucidate transmission routes of MRSA in relation to meat and other foods and to provide the tools for preventing the spread of MRSA. At present the high prevalence of MRSA in meat has not been shown to contribute significantly to the dissemination of MRSA to humans and the possible health hazard for consumers of the presence of MRSA in foods should be further elucidated.

BIOMOLECULAR IDENTIFICATION OF METHICILLIN-RESISTANT STRAINS OF STAPHYLOCOCCUS AUREUS (MRSA) ISOLATED FROM MEAT AND MEAT PROCESSING ENVIRONMENTS

371 samples from meat and meat-environments were collected and examined for the detection of methicillin-resistant Staphylococcus aureus (MRSA). The structural gene for penicillin-binding protein 2a (mecA gene), was amplified by PCR and detected by agarose gel electrophoresis. 96 samples (25.8%), contained S. aureus and 2 of them (2.08%) were mecA positive. Further assays are necessary to evaluate the spread of MRSA in food and food-environments.