Isolation, Virulence, and Antimicrobial Resistance of Methicillin-Resistant Staphylococcus aureus (MRSA) and Methicillin Sensitive Staphylococcus aureus (MSSA) Strains from Oklahoma Retail Poultry Meats

The Epidemiology of Animal-Associated Methicillin-Resistant Staphylococcus aureus

Methicillin-resistant Staphylococcus aureus (MRSA) remains an important etiological factor of human and animal infectious diseases, causing significant economic losses not only in human healthcare but also in the large-scale farming sector. The constantly changing epidemiology of MRSA observed globally affects animal welfare and raises concerns for public health. High MRSA colonization rates in livestock raise questions about the meaning of reservoirs and possible transmission pathways, while the prevalence of MRSA colonization and infection rates among companion animals vary and might affect human health in multiple ways. We present the main findings concerning the circulation of animal-associated MRSA (AA-MRSA) in the environment and factors influencing the direction, mechanisms, and routes of its transmission. Studies have shown it that S. aureus is a multi-host bacterial pathogen; however, its adaptation mechanisms enabling it to colonize and infect both animal and human hosts are still rarely discussed. Finally, we elaborate on the most successful strategies and programs applied limiting the circulation of AA-MRSA among animals and humans. Although MRSA strains colonizing animals rarely infect humans, they undergo host-adaptive evolution enabling them to spread and persist in human populations.

Whole-Genome Epidemiology and Characterization of Methicillin-Susceptible Staphylococcus aureus ST398 From Retail Pork and Bulk Tank Milk in Shandong, China

Staphylococcus aureus (S. aureus) is now regarded as a zoonotic agent. Methicillin-susceptible S. aureus (MSSA) ST398 is a livestock-associated bacterium that is most prevalent in China, but there are currently no data available for Shandong. Therefore, the aim of this study was to investigate the epidemiology and characterization of MSSA ST398 from retail pork and bulk tank milk (BTM) in Shandong. A total of 67 S. aureus isolates were collected from retail pork between November 2017 and June 2018. Among the isolates, high antimicrobial resistance rates were observed for penicillin (97.0%), and 92.5% of the isolates were multi-drug resistant (MDR). Eight sequence types (STs) were identified in the retail pork isolates, and the predominant type was ST15 (n=26), which was followed by ST398 (n=14). Staphylococcal protein A gene (spa) typing identified spa types t034 and t1255 in MSSA ST398 from retail pork. Using whole-genome sequencing analysis, we described the phylogeny of 29 MSSA ST398 isolates that were obtained from retail pork (n=14) and BTM (n=15). The phylogenetic tree showed that the MSSA ST398 isolates from different sources had the same lineage. Among the 29 MSSA ST398 isolates, five resistance genes were detected, and all isolates carried DHA-1. Fifteen toxin genes were detected, and all isolates carried eta, hla, and hlb. In conclusion, this study found that a high risk for MSSA ST398 was present in retail pork and BTM. These findings have major implications for how investigations of MSSA ST398 outbreaks should be conducted in the One-Health context.

Staphylococcus aureus in poultry, with special emphasis on methicillin-resistant strain infection: A comprehensive review from one health perspective

Staphylococcus aureus is a Gram-positive coccus normally present on the skin and internal organs of animals, birds, and humans. Under certain conditions, S. aureus could produce septicemia and affection of the skin, joints, and heart, as well as sepsis and death. The pathogenicity of S. aureus is associated with the presence of some virulent surface proteins and the production of some virulent toxins and enzymes. This pathogen is considered one of the most important and worldwide foodborne causes as it is incriminated in most cases of food poisoning. The hazardous use of antibiotics in the veterinary field leads to the development of multidrug-resistant S. aureus strains that can be transmitted to humans. The incidence of methicillin-resistant S. aureus (MRSA) strains has increased globally. These resistant strains have been detected in live animals, poultry, and humans. In addition, retail animal products, especially those of avian origin, are considered the main source of MRSA strains that can be easily transmitted to humans. MRSA infection is regarded as nosocomial or occupational. Humans get infected with MRSA strains through improper handling or preparation of contaminated animals or poultry carcasses or improper cooking with contaminated meat. Live birds also can transmit MRSA to close-contact workers in poultry farms. Transmission of MRSA infection in hospitals is from an infected individual to a healthy one. Prevention and control of MRSA are based on the application of hygienic measures in farms as well as proper processing, handling, and cooking of retail poultry products. The cooperation between veterinary and human practitioners is a must to avoid the possibility of zoonotic transmission. Accordingly, this review focused on the sources and transmission of MRSA infection, virulence and resistance factors, incidence and prevalence in poultry and different products, antibiotic resistance, and prevention and control strategies.

Prevalence, Enterotoxigenic Potential and Antimicrobial Resistance of Staphylococcus aureus and Methicillin-Resistant Staphylococcus aureus (MRSA) Isolated from Algerian Ready to Eat Foods

Staphylococcus aureus causes a foodborne intoxication due to the production of enterotoxins and shows antimicrobial resistance, as in the case of methicillin-resistant strains (MRSA). Herein, we analyzed 207 ready-to-eat foods collected in Algeria, reporting a S. aureus prevalence of 23.2% (48/207) and respective loads of coagulase positive staphylococci (CPS) ranging from 1.00 ± 0.5 to 5.11 ± 0.24 Log CFU/g. The 48 S. aureus isolates were widely characterized by staphylococcal enterotoxin gene (SEg)-typing and 16S-23S rDNA intergenic spacer region (ISR)-PCR, as well as by detecting tst and mecA genes, genetic determinants of toxic shock syndrome toxin-1 and methicillin resistance, respectively. We found that the S. aureus isolates belonged to seven different SEg-types harboring the following combinations of genes: (1) selW, selX; (2) egc (seG, seI, seM, seN, seO), selW, selX; (3) seA, seH, seK, seQ, selW, selX; (4) seB, selW, selX; (5) seD, selJ, seR, selW, selX; (6) seH, selW, selX, selY; and (7) seA, egc, selW, selX, while among these, 2.1% and 4.2% were tst- and mecA- (staphylococcal chromosomal cassette mec-type IV) positive, respectively. Selected strains belonging to the 12 detected ISR-types were resistant towards antimicrobials including benzylpenicillin, ofloxacin, erythromycin, lincomycin, tetracyclin, kanamycin, oxacillin, and cefoxitin; 8.3% (1/12) were confirmed as MRSA and 16.7% (2/12) were multidrug resistant. The present study shows the heterogeneity of the S. aureus population in Algerian ready-to-eat foods as for their toxigenic potential and antimicrobial resistance, shedding the light on the quality and safety related to the consume of ready-to-eat foods in Algeria.

Prevalence and Characteristics of Staphylococcus aureus Associated with Meat and Meat Products in African Countries: A Review

Antimicrobial resistance has been increasing globally, which negatively affects food safety, veterinary, and human medicine. Ineffective antibiotics may cause treatment failure, which results in prolonged hospitalisation, increased mortality, and consequently, increased health care costs. Staphylococcus aureus causes a diverse range of infections including septicaemia and endocarditis. However, in food, it mainly causes food poisoning by the production of enterotoxins. With the discovery of methicillin-resistant S. aureus strains that have a separate reservoir in livestock animals, which were termed as livestock-associated methicillin-resistant S. aureus (LA-MRSA) in 2005, it became clear that animals may pose another health risk. Though LA-MRSA is mainly transferred by direct contact, food transmission cannot be excluded. While the current strains are not very pathogenic, mitigation is advisable, as they may acquire new virulence genes, becoming more pathogenic, and may transfer their resistance genes. Control of LA-MRSA poses significant problems, and only Norway has an active mitigation strategy. There is limited information about LA-MRSA, MRSA in general, and other S. aureus infections from African countries. In this review, we discuss the prevalence and characteristics of antimicrobial susceptible and resistant S. aureus (with a focus on MRSA) from meat and meat products in African countries and compare it to the situation in the rest of the world.

Occurrence, distribution and pattern analysis of methicillin resistant (MRSA) and methicillin sensitive (MSSA) Staphylococcus aureus on fomites in public facilities

Methicillin-resistant Staphylococcus aureus (MRSA) is a human pathogen incriminated as a causative agent of hospital nosocomial infections as well as a wide range of diseases in communities. This study was conducted to assess the occurrence and distribution of MRSA and methicillin-sensitive (MSSA) on different fomites in public facilities in northern Jordan and to determine their antibiograms, toxin genes profiles, as well as identify their genetic relatedness. A total of 2600 swabs were collected from 14 fomite surfaces in a variety of public facilities including hospitals, universities, schools, transportation sites, and market places. The identity of the 380 S. aureus isolates was confirmed. Among them, 158 (41.6%) were MRSA while the rest of the isolates, 222 (58.4%) were MSSA. MRSA isolates were recovered from all fomites sites. However, among the total collected samples, the percentages of MRSA in public facilities were significantly higher in hospitals and transportation fomites, while percentages of MRSA among fomites sites were higher in public reception sites, chairs, and toilet seats. Antibiotic resistance profiles indicated that 24.5% of the isolates were resistant to cefoxitin, oxacillin, and oxytetracycline. In contrast, only 3.95% were resistant to trimethoprim-sulfamethoxazole, and 15.3% were resistant to ciprofloxacin. Multidrug-resistant patterns were higher in MRSA than in MSSA isolates. There was no apparent difference in toxin gene profiles between MRSA and MSSA. Molecular analysis revealed 85 patterns and 16 clusters at a 9% mean similarity level. In conclusion, this study provides evidence for the potential of MRSA transmission via inanimate surfaces.

Comparative Study of the Difference in Behavior of the Accessory Gene Regulator (Agr) in USA300 and USA400 Community-Associated Methicillin-Resistant Staphylococcus aureus (CA-MRSA)

Community-associated Methicillin-Resistant Staphylococcus aureus (CA-MRSA) is notorious as a leading cause of soft tissue infections. Despite several studies on the Agr regulator, the mechanisms of action of Agr on the virulence factors in different strains are still unknown. To reveal the role of Agr in different CA-MRSA, we investigated the LACΔagr mutant and the MW2Δagr mutant by comparing LAC (USA300), MW2 (USA400), and Δagr mutants. The changes of Δagr mutants in sensitivity to oxacillin and several virulence factors such as biofilm formation, pigmentation, motility, and membrane properties were monitored. LACΔagr and MW2Δagr mutants showed different oxacillin sensitivity and biofilm formation compared to the LAC and MW2 strains. Regardless of the strain, the motility was reduced in Δagr mutants. And there was an increase in the long chain fatty acid in phospholipid fatty acid composition of Δagr mutants. Other properties such as biofilm formation, pigmentation, motility, and membrane properties were different in both Δagr mutants. The Agr regulator may have a common role like the control of motility and straindependent roles such as antibiotic resistance, biofilm formation, change of membrane, and pigment production. It does not seem easy to control all MRSA by targeting the Agr regulator only as it showed strain-dependent behaviors.

Frequency of osteonecrosis in bisphosphonate users submitted to dental procedures: A systematic review

OBJECTIVE

To determine the frequency of osteonecrosis of the jaw in bisphosphonate users submitted to dental procedures.

METHODS

This systematic review searched the sources: MEDLINE, EMBASE, Web of Science, Scopus, and Virtual Health Library, with no restriction on language or publication date. Reviewers, in pairs and independently, selected the studies, extracted their data, and assessed the risk of bias. Meta-analyses were pooled using the DerSimonian and Laird random effects model.

RESULTS

A total of 27 studies (5391 participants) were included. The most reported bisphosphonates were zoledronate (n = 17 studies) and alendronate (n = 19) for treating cancers (n = 11) and osteoporosis (n = 16), respectively. Twelve studies were of low methodological quality. The frequency of osteonecrosis was 2.7% (95% CI: 0.9-5.2%) and proved higher for intravenous [6.9% (0.7-17.3%)] than oral [0.2% (0.9-5.2%)] bisphosphonate use. No association between longer treatment duration and greater frequency of osteonecrosis was observed.

CONCLUSIONS

Higher frequency of osteonecrosis was observed in intravenous bisphosphonate users submitted to dental extraction. Further studies collecting more detailed information on the bisphosphonates used and of greater methodological rigor are warranted to confirm these findings and better inform prescribers, dental surgeons, and other professionals on risks of bisphosphonate use in this patient group.

Prevalence and Characteristics of Multidrug-Resistant Livestock-Associated Methicillin-Resistant Staphylococcus aureus (LA-MRSA) CC398 Isolated from Quails (Coturnix Coturnix Japonica) Slaughtered for Human Consumption

Simple Summary

Methicillin-resistant Staphylococcus aureus (MRSA) is an important pathogen in both humans and animals worldwide. MRSA associated with livestock is a zoonotic pathogen that has been reported in several animals and, although its infections in humans are rare, this strain is recognized as an occupational hazard for people working in direct contact with livestock. Thus, we aimed to isolate MRSA from quails and to characterize their antimicrobial resistance and genetic lineages. One hundred swab samples were recovered from quails at the slaughterhouse. To investigate the prevalence and antimicrobial resistance of MRSA in poultry, we conducted this study on 100 quails slaughtered for human consumption. The antimicrobial resistance was investigated in all isolates as well as virulence genes and genetic lineages. Twenty-nine MRSA were isolated. The results showed that all MRSA isolates had resistance to multiple antibiotics. All strains were classified as livestock-associated. Most strains belonged to a well-known livestock-associated lineage: CC398.

Abstract

Livestock-associated MRSA (LA-MRSA) is a zoonotic pathogen that has been reported in several animals, and it is often associated with clonal complex (CC) 398. We aimed to isolate MRSA from quails and to characterize their antimicrobial resistance and genetic lineages. One hundred swab samples were recovered from quails at the slaughterhouse. The swabs were inoculated onto CHROMagar™ MRSA agar plates for MRSA isolation. The presence of antimicrobial-resistant genes and virulence factors was investigated by PCR. All strains were typed by MLST, SCCmec-, spa- and agr-typing. From the 100 samples, 29 MRSA were isolated. All strains were resistant to penicillin, cefoxitin, ciprofloxacin, erythromycin and clindamycin and carried the blaZ, mecA, ermB and ermC genes. All strains, except one, showed resistance to tetracycline and harbored the tetM, tetK and tetL genes in different combinations. Twenty strains belonged to ST398 and SCCmec type V, and nine strains belonged to the new ST6831. Twenty-eight out of twenty-nine strains were ascribed to t011 and one to t108. As far as we know, this is the first report of MRSA from quails slaughtered for human consumption. Most strains belonged to ST398-t011, which is the most common LA-MRSA clone found in livestock in Europe.

Staphylococcus aureus enhances biofilm formation, aerotolerance, and survival of Campylobacter strains isolated from retail meats

In retail meat products, Campylobacter jejuni, C. coli, and Staphylococcus aureus have been reported in high prevalence. The polymicrobial interaction between Campylobacter and other bacteria could enhance Campylobacter survival during the adverse conditions encountered during retail meat processing and storage. This study was designed to investigate the potential role of S. aureus from retail meats in enhancing the survival of Campylobacter exposed to low temperature, aerobic conditions, and biofilm formation. Results indicated that viable S. aureus cells and filter-sterilized cell-free media obtained from S. aureus prolonged the survival of Campylobacter at low temperature and during aerobic conditions. Biofilm formation of Campylobacter strains was significantly enhanced in the presence of viable S. aureus cells, but the results were inconclusive when extracts from cell-free media were used. In conclusion, the presence of S. aureus cells enhances survivability of Campylobacter strains in adverse conditions such as low temperature and aerobic conditions. Further investigations are warranted to understand the interaction between Campylobacter and S. aureus, and effective intervention strategies are needed to reduce the incidence of both foodborne pathogens in retail meat products.

Prevalence of antimicrobial resistance genes and its association with restricted antimicrobial use in food-producing animals: a systematic review and meta-analysis

BACKGROUND

There is ongoing debate regarding potential associations between restrictions of antimicrobial use and prevalence of antimicrobial resistance (AMR) in bacteria.

OBJECTIVES

To summarize the effects of interventions reducing antimicrobial use in food-producing animals on the prevalence of AMR genes (ARGs) in bacteria from animals and humans.

METHODS

We published a full systematic review of restrictions of antimicrobials in food-producing animals and their associations with AMR in bacteria. Herein, we focus on studies reporting on the association between restricted antimicrobial use and prevalence of ARGs. We used multilevel mixed-effects models and a semi-quantitative approach based on forest plots to summarize findings from studies.

RESULTS

A positive effect of intervention [reduction in prevalence or number of ARGs in group(s) with restricted antimicrobial use] was reported from 29 studies for at least one ARG. We detected significant associations between a ban on avoparcin and diminished presence of the vanA gene in samples from animals and humans, whereas for the mecA gene, studies agreed on a positive effect of intervention in samples only from animals. Comparisons involving mcr-1, blaCTX-M, aadA2, vat(E), sul2, dfrA5, dfrA13, tet(E) and tet(P) indicated a reduced prevalence of genes in intervention groups. Conversely, no effects were detected for β-lactamases other than blaCTX-M and the remaining tet genes.

CONCLUSIONS

The available body of scientific evidence supported that restricted use of antimicrobials in food animals was associated with an either lower or equal presence of ARGs in bacteria, with effects dependent on ARG, host species and restricted drug.

Mapping foodborne pathogen contamination throughout the conventional and alternative poultry supply chains

Recently, there has been a consumer push for natural and organic food products. This has caused alternative poultry production, such as organic, pasture, and free-range systems, to grow in popularity. Due to the stricter rearing practices of alternative poultry production systems, different types of levels of microbiological risks might be present for these systems when compared to conventional production systems. Both conventional and alternative production systems have complex supply chains that present many different opportunities for flocks of birds or poultry meat to be contaminated with foodborne pathogens. As such, it is important to understand the risks involved during each step of production. The purpose of this review is to detail the potential routes of foodborne pathogen transmission throughout the conventional and alternative supply chains, with a special emphasis on the differences in risk between the two management systems, and to identify gaps in knowledge that could assist, if addressed, in poultry risk-based decision making.

The impact of essential oils on antibiotic use in animal production regarding antimicrobial resistance - a review

Population growth directly affects the global food supply, demanding a higher production efficiency without farmland expansion - in view of limited land resources and biodiversity loss worldwide. In such scenario, intensive agriculture practices have been widely used. A commonly applied method to maximize yield in animal production is the use of subtherapeutic doses of antibiotics as growth promoters. Because of the strong antibiotic selection pressure generated, the intense use of antibiotic growth promoters (AGP) has been associated to the rise of antimicrobial resistance (AMR). Also, cross-resistance can occur, leading to the emergence of multidrug-resistant pathogens and limiting treatment options in both human and animal health. Thereon, alternatives have been studied to replace AGP in animal production. Among such alternatives, essential oils and essential oil components (EOC) stand out positively from others due to, besides antimicrobial effectiveness, improving zootechnical indexes and modulating genes involved in resistance mechanisms. This review summarizes recent studies in essential oils and EOC for zoonotic bacteria control, providing detailed information about the molecular-level effects of their use in regard to AMR, and identifying important gaps to be filled within the animal production area.

Prevalence and risk of staphylococcal and coliform carcass contamination of chickens slaughtered in the informal market in Gauteng, South Africa

Purpose

The primary objective was to determine the prevalence of indicator microorganisms [Staphylococcus aureus, non-S. aureus staphylococci (NSAS), coliforms and aerobic bacteria] for contamination of chicken carcasses, carcass drip and rinse water from the informal chicken market in Gauteng, South Africa.

Design/methodology/approach

Chicken swabs, chicken drips and rinse waters were collected from 151 chickens from 47 random outlets. Pre-tested questionnaires were administered to capture the risk factors for bacterial contamination. Standard microbiological procedures were conducted for isolation and enumeration of target bacteria.

Findings

NSAS (64% and 41%) and S. aureus (12% and 31%) were prevalent on carcasses and in carcass drip respectively. Coliforms (62%) and aerobic bacteria (85%) were detected in rinse water. Significant risk factors for contamination of carcasses with NSAS, S. aureus and coliform organisms were: evisceration of chickens on the same location used for sale, cleaning of display counter with dirty clothes/wipes, holding of differently sourced chickens in the same cage prior to slaughter, not cleaning the display table/counter and hands at all, washing knives in rinse water, high turnover of daily slaughter and length of time to display chickens.

Research limitations/implications

The limitations of this research were the limited geographical coverage and small sample size.

Practical implications

The isolation of these indicator microorganisms suggests the potential presence of other chicken-borne pathogens not tested for in the study.

Social implications

The findings serve to inform policy on public health and street-vended food and can guide control on good sanitary practices.

Originality/value

This is the first comprehensive report on ready to eat chickens from the informal markets in Gauteng, South Africa.

Comparative Genomics of Plasmid-Bearing Staphylococcus aureus Strains Isolated From Various Retail Meats

Food poisoning due to the consumption of Staphylococcus aureus contaminated food is a major health problem worldwide. In this study, we sequenced the genomes of ten plasmid-bearing S. aureus strains isolated from retail beef, chicken, turkey, and pork. The chromosomes of the strains varied in size from 2,654,842 to 2,807,514 bp, and a total of 25 plasmids were identified ranging from 1.4 to 118 kb. Comparative genomic analysis revealed similarities between strains isolated from the same retail meat source, indicating an origin-specific genomic composition. Genes known to modulate attachment, invasion, and toxin production were identified in the 10 genomes. Strains from retail chicken resembled human clinical isolates with respect to virulence factors and genomic islands, and retail turkey and pork isolates shared similarity with S. aureus from livestock. Most chromosomes contained antimicrobial resistance, heavy metal resistance, and stress response genes, and several plasmids contained genes involved in antimicrobial resistance and virulence. In conclusion, the genomes of S. aureus strains isolated from retail meats showed an origin-specific composition and contained virulence and antimicrobial resistance genes similar to those present in human clinical isolates.

Prevalence and Characteristics of Antimicrobial-Resistant Staphylococcus aureus and Methicillin-Resistant Staphylococcus aureus from Retail Meat in Korea

This study was to investigate the prevalence and characteristics of antimicrobial-resistant Staphylococcus aureus and methicillin-resistant S. aureus (MRSA) from 4,264 retail meat samples including beef, pork, and chicken in Korea between 2013 and 2018. A broth microdilution antimicrobial susceptibility testing was performed for S. aureus. Molecular typing by multilocus sequence typing (MLST), spa typing, and pulsed-field gel electrophoresis (PFGE), was performed on mecA-positive S. aureus strain. S. aureus was isolated at a rate of 18.2% (777/4,264), of which MRSA comprised 0.7% (29 strains). MLST analysis showed that 11 out of the 29 MRSA isolates were predominantly sequence type (ST) 398 (37.9%). In addition, ST72, ST692, ST188, ST9, and ST630 were identified in the MRSA isolates. The spa typing results were classified into 11 types and showed a high correlation with MLST. The antimicrobial resistance assays revealed that MRSA showed 100% resistance to cefoxitin and penicillin. In addition, resistance to tetracycline (62.1%), clindamycin (55.2%), and erythromycin (55.2%) was relatively high; 27 of the 29 MRSA isolates exhibited multidrug resistance. PFGE analysis of the 18 strains excluding the 11 ST398 strains exhibited a maximum of 100% homology and a minimum of 64.0% homology. Among these, three pairs of isolates showed 100% homology in PFGE; these results were consistent with the MLST and spa typing results. Identification of MRSA at the final consumption stage has potential risks, suggesting that continuous monitoring of retail meat products is required.

[Methicillin-resistant Staphylococcus aureus in the Americas: systematic review and metanalysis of prevalence in food-producing animalsStaphylococcus aureus resistente a la meticilina en la Región de las Américas: revisión sistemática y metanálisis de la prevalencia en la actividad agropecuaria]

OBJECTIVE

To determine the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) in animals used to produce foods in the Americas.

METHOD

A systematic literature review was performed in the following databases: Scopus, Web of Science, MEDLINE, EMBASE, and Virtual Health Library. Articles published in the past 10 years, without language limits, were selected. The outcome of interest was the prevalence of MRSA in food-producing animals. Prevalence rates were meta-analyzed in grouped random effects models using the DerSimonian and Laird method. The geographic distribution of MRSA and the time trend of resistance were also analyzed.

RESULTS

Of 19 studies included, 11 were performed in the United States and 11 analyzed pig samples. Five studies were performed in South America. The samples analyzed in the studies were collected in farming, processing, and retail sites. MRSA prevalence in the Americas was 7.6% (95%CI: 5.6-9.5%), and was higher in pigs [12.6% (95%CI: 7.0-18.2%)] followed by bovine cattle [2.4% (95%CI: 1.2-3.7%)] and poultry [1.8% (95CI%: 0.3-3.4%)]. MRSA prevalence was higher in pigs in North America and bovine cattle in Latin America. There was no significant variation in MRSH prevalence along the 10-year period analyzed.

CONCLUSIONS

MRSA prevalence in food-producing animals in the Americas was higher in pigs, without significant changes across time.

Methicillin-resistant Staphylococcus aureus (MRSA) isolated from chicken meat and giblets often produces staphylococcal enterotoxin B (SEB) in non-refrigerated raw chicken livers

Methicillin-resistant Staphylococcus aureus (MRSA) is responsible for several difficult-to-treat infections and staphylococcal food poisoning (SFP). This study was conducted to investigate the prevalence and enterotoxigenicity of MRSA in broiler chicken meat and giblets. A total of 5.5% (8/144) of the examined samples were contaminated with mecA positive/mecC negative MRSA, with staphylococcal counts of approximately 10² colony forming units (CFU)/g in breast, leg and gizzard samples and approximately 3.3 × 10³ CFU/g in frozen liver samples. Most MRSA isolates (75%, 6/8) harboured the staphylococcal enterotoxin B (seb) gene. Reverse transcription-PCR (RT-PCR) showed that MRSA isolates initiated SEB production in experimentally contaminated chicken livers within 24 h of storage at temperatures over 8 °C. SEB was maximally produced at 24 °C when the MRSA counts reached 7.3 × 10³ ± 1.2 × 10³ CFU/g sample homogenate. The current study concludes that the main broiler chicken MRSA isolates in Egypt harbour the seb gene. To mitigate possible SEB production, especially in broiler chicken livers, a maximum "out of refrigeration" time limit should be implemented for cold chain poultry products.

Staphylococcus aureus in Animals

Staphylococcus aureus is a mammalian commensal and opportunistic pathogen that colonizes niches such as skin, nares and diverse mucosal membranes of about 20-30% of the human population. S. aureus can cause a wide spectrum of diseases in humans and both methicillin-sensitive and methicillin-resistant strains are common causes of nosocomial- and community-acquired infections. Despite the prevalence of literature characterising staphylococcal pathogenesis in humans, S. aureus is a major cause of infection and disease in a plethora of animal hosts leading to a significant impact on public health and agriculture. Infections in animals are deleterious to animal health, and animals can act as a reservoir for staphylococcal transmission to humans.Host-switching events between humans and animals and amongst animals are frequent and have been accentuated with the domestication and/or commercialisation of specific animal species. Host-switching is typically followed by subsequent adaptation through acquisition and/or loss of mobile genetic elements such as phages, pathogenicity islands and plasmids as well as further host-specific mutations allowing it to expand into new host populations.In this chapter, we will be giving an overview of S. aureus in animals, how this bacterial species was, and is, being transferred to new host species and the key elements thought to be involved in its adaptation to new ecological host niches. We will also highlight animal hosts as a reservoir for the development and transfer of antimicrobial resistance determinants.

Molecular Characterization of Staphylococcus aureus Plasmids Associated With Strains Isolated From Various Retail Meats

Staphylococcus aureus is considered one of the most important foodborne bacterial pathogens causing food poisoning and related illnesses. S. aureus strains harbor plasmids encoding genes for virulence and antimicrobial resistance, but few studies have investigated S. aureus plasmids, especially megaplasmids, in isolates from retail meats. Furthermore, knowledge about the distribution of genes encoding replication (rep) initiation proteins in food isolates is lacking. In this study, the prevalence of plasmids in S. aureus strains isolated from retail meats purchased in Oklahoma was investigated; furthermore, we evaluated associations between rep families, selected virulence and antimicrobial resistance genes, and food source origin. Two hundred and twenty-two S. aureus isolates from chicken (n = 55), beef liver (n = 43), pork (n = 42), chicken liver (n = 29), beef (n = 24), turkey (n = 22), and chicken gizzards (n = 7) were subjected to plasmid screening with alkaline lysis and PFGE to detect small-to-medium sized and large plasmids, respectively. The S. aureus isolates contained variable sizes of plasmids, and PFGE was superior to alkaline lysis in detecting large megaplasmids. A total of 26 rep families were identified by PCR, and the most dominant rep families were rep₁₀ and rep₇ in 164 isolates (89%), rep₂₁ in 124 isolates (56%), and rep₁₂ in 99 isolates (45%). Relationships between selected rep genes, antimicrobial resistance and virulence genes, and meat sources were detected. In conclusion, S. aureus strains isolated from retail meats harbor plasmids with various sizes and there is an association between rep genes on these plasmids and the meat source or the antimicrobial resistance of the strains harboring them.

Comparison of different approaches to antibiotic restriction in food-producing animals: stratified results from a systematic review and meta-analysis

BACKGROUND

We have previously reported, in a systematic review of 181 studies, that restriction of antibiotic use in food-producing animals is associated with a reduction in antibiotic-resistant bacterial isolates. While informative, that report did not concretely specify whether different types of restriction are associated with differential effectiveness in reducing resistance. We undertook a sub-analysis of the systematic review to address this question.

METHODS

We created a classification scheme of different approaches to antibiotic restriction: (1) complete restriction; (2) single antibiotic-class restriction; (3) single antibiotic restriction; (4) all non-therapeutic use restriction; (5) growth promoter and prophylaxis restriction; (6) growth promoter restriction and (7) other/undetermined. All studies in the original systematic review that were amenable to meta-analysis were included into this substudy and coded by intervention type. Meta-analyses were conducted using random effects models, stratified by intervention type.

RESULTS

A total of 127 studies were included. The most frequently studied intervention type was complete restriction (n=51), followed by restriction of non-therapeutic (n=33) and growth promoter (n=19) indications. None examined growth promoter and prophylaxis restrictions together. Three and seven studies examined single antibiotic-class and single antibiotic restrictions, respectively; these two intervention types were not significantly associated with reductions in antibiotic resistance. Though complete restrictions were associated with a 15% reduction in antibiotic resistance, less prohibitive approaches also demonstrated reduction in antibiotic resistance of 9%-30%.

CONCLUSION

Broad interventions that restrict global antibiotic use appear to be more effective in reducing antibiotic resistance compared with restrictions that narrowly target one specific antibiotic or antibiotic class. Importantly, interventions that allow for therapeutic antibiotic use appear similarly effective compared with those that restrict all uses of antibiotics, suggesting that complete bans are not necessary. These findings directly inform the creation of specific policies to restrict antibiotic use in food-producing animals.

Prevalence and risk factors contributing to antibiotic-resistant Staphylococcus aureus isolates from poultry meat products in South Africa, 2015-2016

Staphylococcus aureus, including methicillin-resistant strains, has been detected in food products of animal origin globally. Limited data have been reported on the factors contributing to antibiotic resistance of food-borne pathogens in South Africa. The primary aim of this study was to determine the prevalence of S. aureus, including antibiotic-resistant strains, in poultry meat products as well as the evaluation of potential risk factors for contamination of poultry meat products with antibiotic-resistant S. aureus isolates. A cross-sectional investigation was conducted in municipalities located across the nine provinces of South Africa, which included abattoirs, meat processing facilities, retail outlets and cold stores at the major ports of entry into South Africa. Staphylococcus aureus isolates obtained from various poultry meat products were tested for susceptibility to 14 antibiotic compounds representing 10 antibiotic classes using the Kirby–Bauer disc diffusion method. Potential risk factors were evaluated using a logistic regression model. Of the 311 samples tested, 34.1% (n = 106) were positive for S. aureus (95% confidence interval [CI], 28.9% – 39.7%). Seventy-two of the 106 isolates were randomly selected for antibiotic sensitivity testing. Twenty-one per cent (n = 15) of the isolates selected for sensitivity testing were methicillin-resistant strains (95% CI, 12.2% – 32.0%). Multi-drug resistance was detected in 22.2% (n = 16) of these isolates tested (95% CI, 13.3% – 33.6%). Origin of the product (p = 0.160), type of meat product (p = 0.962), type of facility (p = 0.115) and facility hygiene practices (p = 0.484) were not significantly associated with contamination of poultry meat products with methicillin-resistant strains. The study provides baseline data for further studies on antibiotic resistance risk assessments for food-borne pathogens, including S. aureus, which should guide the implementation plans of the South African National Antimicrobial Resistance Strategy Framework, 2017–2024.

Examination of unintended consequences of antibiotic use restrictions in food-producing animals: Sub-analysis of a systematic review

Antimicrobial resistance is considered one of the greatest threats to global and public health today. The World Health Organization, the Food and Agriculture Organization, and the World Organisation for Animal Health, known as the Tripartite Collaboration, have called for urgent action. We have previously published a systematic review of 181 studies, demonstrating that interventions that restrict antibiotic use in food-producing animals are associated with a reduction in antibiotic resistant bacterial isolates in both animals and humans. What remains unknown, however, are whether (and what) unintended consequences may arise from such interventions. We therefore undertook a sub-analysis of the original review to address this research question. A total of 47 studies described potential consequences of antibiotic restrictions. There were no consistent trends to suggest clear harm. There may be increased bacterial contamination of food products, the clinical significance of which remains unclear. There is a need for rigorous evaluation of the unintended consequences of antibiotic restrictions in human health, food availability, and economics, given their possible widespread implications.

Antibiotic resistance is lower in Staphylococcus aureus isolated from antibiotic-free raw meat as compared to conventional raw meat

The frequent use of antibiotics contributes to antibiotic resistance in bacteria, resulting in an increase in infections that are difficult to treat. Livestock are commonly administered antibiotics in their feed, but there is current interest in raising animals that are only administered antibiotics during active infections. Staphylococcus aureus (SA) is a common pathogen of both humans and livestock raised for human consumption. SA has achieved high levels of antibiotic resistance, but the origins and locations of resistance selection are poorly understood. We determined the prevalence of SA and MRSA in conventional and antibiotic-free (AF) meat products, and also measured rates of antibiotic resistance in these isolates. We isolated SA from raw conventional turkey, chicken, beef, and pork samples and also from AF chicken and turkey samples. We found that SA contamination was common, with an overall prevalence of 22.6% (range of 2.8-30.8%) in conventional meats and 13.0% (range of 12.5-13.2%) in AF poultry meats. MRSA was isolated from 15.7% of conventional raw meats (range of 2.8-20.4%) but not from AF-free meats. The degree of antibiotic resistance in conventional poultry products was significantly higher vs AF poultry products for a number of different antibiotics, and while multi-drug resistant strains were relatively common in conventional meats none were detected in AF meats. The use of antibiotics in livestock contributes to high levels of antibiotic resistance in SA found in meat products. Our results support the use of AF conditions for livestock in order to prevent antibiotic resistance development in SA.

Molecular Characterization and Antibiotic Resistance of Foodborne Pathogens in Street-Vended Ready-to-Eat Meat Sold in South Africa

ABSTRACT

The consumption of food contaminated with microbial populations remains a key route of foodborne infection in developing countries and creates a serious public health burden. This study aimed at identifying foodborne pathogens and their antibiotic resistance profiles in ready-to-eat meat sold in public eateries in the Johannesburg area. A total of 115 samples were examined for the incidence of bacteria pathogens and their antibiotic resistance profiles against commonly used antibiotics (ampicillin, tetracycline, chloramphenicol, erythromycin, ciprofloxacin, streptomycin, and sulphonamides) using the molecular and the disc diffusion methods. Fifteen bacteria species were detected in the samples. Staphylococcus aureus had the highest prevalence (25%), and 53.33% of the isolates exhibited multidrug resistance to the antibiotics tested. Among the isolated bacteria, S. aureus; was resistant to at least six antimicrobial agents, whereas 100% of S. aureus,Enterococcus faecalis, and Planomicrobium glaciei were resistant to streptomycin, ciprofloxacin, and chloramphenicol, respectively. This study revealed that a wide diversity of bacteria species contaminate meat sold on the street, which indicates that consumers of ready-to-eat meat sold in public eateries are at risk of food poisoning. Hence, strict intervention strategies should be put in place by government agencies to reduce the menace of food poisoning in the country.

HIGHLIGHTS

RTE meats were analyzed for microbial contamination. Foodborne pathogens were detected in the meat samples. Antibiotic resistance profiles were tested. RTE meats contain foodborne pathogens, and isolates exhibited antibiotic resistance. Consumers of RTE meat in the Johannesburg CBD are at risk of food poisoning.

Prevalence, Serotyping, Molecular Typing, and Antimicrobial Resistance of Salmonella Isolated From Conventional and Organic Retail Ground Poultry

Ground poultry is marketed as a healthier alternative to ground beef despite the fact that poultry is a major source of foodborne Salmonella. The objectives of this study were to determine the prevalence of Salmonella in Oklahoma retail ground poultry and to characterize representative isolates by serotyping, antimicrobial resistance, PFGE patterns, and large plasmid profiling. A total of 199 retail ground poultry samples (150 ground turkey and 49 ground chicken) were investigated. The overall prevalence of Salmonella in ground poultry was 41% (82/199), and the incidence in conventional samples (47%, 66/141) was higher than in organic samples (27%, 16/58). The prevalence of Salmonella in organic ground chicken and organic ground turkey was 33% (3/9) and 26% (13/49), respectively. Twenty six Salmonella isolates (19 conventional and 7 organic) were chosen for further characterization. The following six serotypes and number of isolates per serotype were identified as follows: Tennessee, 8; Saintpaul, 4; Senftenberg, 4; Anatum, 4 (one was Anatum_var._15+); Ouakam, 3; and Enteritidis, 3. Resistance to 16 tested antimicrobials was as follows: gentamycin, 100% (26/26); ceftiofur, 100% (26/26); amoxicillin/clavulanic acid, 96% (25/26); streptomycin, 92% (24/26); kanamycin, 88% (23/26); ampicillin, 85% (22/26); cephalothin, 81% (21/26); tetracycline, 35% (9/26); sulfisoxazole, 27% (7/26); nalidixic acid, 15% (4/26); and cefoxitin, 15% (4/26). All isolates were susceptible to amikacin, chloramphenicol, ceftriaxone, and trimethoprim/sulfamethoxazole. All screened isolates were multidrug resistant (MDR) and showed resistance to 4-10 antimicrobials; isolates from organic sources showed resistance to 5-7 antimicrobials. PFGE was successful in clustering the Salmonella isolates into distinct clusters that each represented one serotype. PFGE was also used to investigate the presence of large plasmids using S1 nuclease digestion. A total of 8/26 (31%) Salmonella isolates contained a ∼100 Kb plasmid that was present in all Anatum and Ouakam isolates. In conclusion, the presence of multidrug resistant Salmonella with various serotypes, PFGE profiles, and large plasmids in ground poultry stresses the importance of seeking novel interventions to reduce the risk of this foodborne pathogen. Multidrug resistance (MDR) is considered a high additional risk and continued surveillance at the retail level could minimize the risk for the consumer.

Antibiotic Susceptibility profile of Staphylococcus aureus isolated from sausages in Meknes, Morocco

Background and Aims

Staphylococcus aureus is one of the most common causes of foodborne disease worldwide, due to the consumption of food contaminated by their toxins. This study aimed to determine the prevalence and the antimicrobial resistance of S. aureus isolated from sausages in Meknes city of Morocco.

Materials and Methods

A total of 156 samples (Beef sausages, Turkey sausages, and Artisanal sausages "Merguez") were collected from different shopping sites (butchery, supermarket, street vendors, and weekly market "Souk") and used for the isolation of S. aureus. All the isolated strains were tested for their antimicrobials resistance to 16 antibiotics.

Results

Our results showed the presence of S. aureus in 63 samples (40.38%). Furthermore, the antimicrobial resistance study showed that 84.13% of isolated S. aureus were resistant to streptomycin, 76.20% to tetracycline, 42.86% to ampicillin, 41.27% to doxycycline, 38.1% to penicillin G, and 19.05% to chloramphenicol with the presence of 25 different phenotypic profiles. However, all isolated strains were sensitive to oxacillin, cefoxitin, gentamicin, and vancomycin.

Conclusion

The findings of this study revealed consumption of sausages as a potential risk of foodborne poisonings because of its contamination with the multi-resistant strains of S. aureus. Moreover, this contamination is related to the season, sampling sites and the origin of the raw material.

Antimicrobial Resistance Profiles of Staphylococcus aureus Isolated from Meat Carcasses and Bovine Milk in Abattoirs and Dairy Farms of the Eastern Cape, South Africa

Background: Staphylococcus aureus (S. aureus) occasionally threatens the life of the host as a persistent pathogen even though it is normal flora of humans and animals. We characterized drug resistance in S. aureus isolated from animal carcasses and milk samples from the abattoirs and dairy farms in the Eastern Cape Province. Methods: A total of 1000 meat swab samples and 200 raw milk samples were collected from selected abattoirs and dairy farms. S. aureus was isolated and positively identified using biochemical tests and confirmed by molecular methods. An antibiotic susceptibility test was performed on all isolates for 14 antibiotics and correspondent genes were detected. Results: Of the 1200 samples collected, 134 (11.2%) samples were positive for S. aureus. Resistance ranged from 71.6% for penicillin G to 39.2% for tetracycline. A resistance gene (blaZ) was detected in 13 (14.9%), while msrA was found in 31 (52.5%) of S. aureus isolates. Conclusions: The present result shows the potential dissemination of multidrug-resistant S. aureus strains in the dairy farms and abattoirs in the Eastern Cape. Therefore, this implies that the organism may rapidly spread through food and pose serious public health risk.

Prevalence of methicillin-resistant Staphylococcus aureus (MRSA) in broilers and workers at 'pluck shops' in Trinidad

Livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) is a cause of zoonotic infections in many countries. People with occupational contact with food animal production are at risk of colonization. The aim of this study was to determine the prevalence of MRSA and their frequency of resistance to other antimicrobial agents from broilers and workers at the 'pluck shops' in Trinidad. For isolation of MRSA, choanal, cloacal and pharyngeal swabs taken from broilers and nasal swabs from humans were enriched then plated on CHROMagar MRSA and Brilliance MRSA. MRSA was confirmed using the PBP2a test kit, resistance to oxacillin and cefoxitin and polymerase chain reaction (PCR) for the mecA gene. Antimicrobial resistance of the MRSA isolates to 16 antimicrobial agents was determined using the disc diffusion method. Of the 287 broilers and 47 humans sampled, MRSA was isolated at a frequency of 2 (0.7%) and 0 (0.0%) respectively. All the MRSA isolates exhibited resistance to one or more of the 16 antimicrobial agents. The study demonstrated that broilers at 'pluck shops' in Trinidad harbor MRSA. This is the first isolation of MRSA from poultry in Trinidad, West Indies, and this finding is of public health significance since occupational exposure of humans can lead to increased risk of acquiring MRSA infections.

Prevalence, resistance pattern, and molecular characterization of Staphylococcus aureus isolates from healthy animals and sick populations in Henan Province, China

Background

Staphylococcus aureus is one of the most prevalent pathogens and a causative agent of a variety of infections in humans and animals. A total of 640 samples were collected from healthy animals and patients from 2013 to 2014 in Henan Province, China, to investigate the prevalence and perform molecular characterization of S. aureus. Antimicrobial resistance and virulence genes were determined and pulsed-field gel electrophoresis (PFGE) and staphylococcal cassette chromosome mec (SCCmec) typing were performed.

Results

Overall, 22.3% (n = 143) of the samples were positive for S. aureus. The prevalence of methicillin-resistant S. aureus (MRSA) was 5.59%. Capsular polysaccharide locus type 5 (Cap5; 56.64%) was the dominant serotype. S. aureus strains showed high resistance to penicillin (96.50%), ciprofloxacin (52.45%), amikacin (67.83%), erythromycin (96.50%), lincomycin (97.20%), and tetracycline (68.53%) and 109 (76.2%) isolates harbored six or more tested resistance genes. The most predominant resistance genes were aphA (52.45%), ermC (53.15%), and tetM (52.45%). Eighty-seven (60.8%) isolates harbored six or more tested virulence genes. The most predominant enterotoxin genes were sed (20.28%), sej (20.98%), sep (14.69%), and set (37.76%). The prevalence of lukED gene was (57.34%), and a small number of isolates carried pvl (5.59%) and TSST-1 (2.80%). A total of 130 (82.52%) isolates could be typed by PFGE with SmaI digestion. PFGE demonstrated that 45 different patterns (P) that were grouped into 17 pulsotypes and 28 separate pulsotypes using a 90% cut-off value. A total of 118 (82.52%) isolates were successfully typed by spa, and 26 spa types were identified, t15075 (14.00%) and t189 (12.59%) were the most common types. SCCmec types were detected from eight MRSA isolates, with the most prevalent type being SCCmec IVa. MRSA-SCCmec Iva-t437 was observed in human isolates.

Conclusion

This study revealed a high prevalence of S. aureus in healthy animals and patients from Henan Province, China. Resistant S. aureus exhibited varying degrees of multidrug resistance. The presence of antibiotic resistance and virulence genes may facilitate the spread of S. aureus strains and pose a potential threat to public health, highlighting the need for vigilant monitoring of these isolates at the human–animal interface.

Electronic supplementary material

The online version of this article (10.1186/s13099-018-0254-9) contains supplementary material, which is available to authorized users.

Methicillin-Resistant Staphylococcus aureus in Poultry and Poultry Meat: A Meta-Analysis

Methicillin-resistant Staphylococcus aureus (MRSA) is a bacterium that colonizes and infects various host species and has been found in the poultry production chain, raising concerns about possible transmission from farm to fork. The objective of this study was to use meta-analytical methods to estimate the pooled prevalence of MRSA in chickens, turkeys, chicken meat, and turkey meat. Three electronic databases (PubMed, LILACS, and SciELO) were searched to establish MRSA prevalence from 51 studies published from 2003 through May 2017. The heterogeneity was assessed, and the pooled MRSA prevalence was calculated by using the random effects model according to the method of DerSimonian and Laird. Pooled MRSA prevalence (95% confidence interval [CI]) in turkeys, turkey meat, broilers, and chicken meat was 36% (1 to 78%), 13% (1 to 28%), 5% (2 to 9%), and 5% (3 to 8%), respectively. South America had the highest MRSA prevalence (27%; 95% CI, 17 to 37%), and North America had the lowest (1%; 95% CI, 0 to 2%). Livestock-associated MRSA has been isolated from poultry and poultry meat, indicating that this variant can spread from farm to fork. The presence of MRSA in poultry and poultry meat poses risks to public health, and steps should be taken to mitigate the contamination and spread of this bacterium along the poultry production chain.

Complete Genome Sequences of Plasmid-Bearing Multidrug-Resistant Campylobacter jejuni and Campylobacter coli Strains with Type VI Secretion Systems, Isolated from Retail Turkey and Pork

We report the complete genome sequences of multidrug-resistant Campylobacter jejuni and Campylobacter coli isolated from retail turkey and pork, respectively. The chromosomes of these two isolates contained type VI secretion system genes. The two isolates also harbored large plasmids with antimicrobial resistance genes possibly contributing to their multidrug resistance.

Recombination-Mediated Host Adaptation by Avian Staphylococcus aureus

Staphylococcus aureus are globally disseminated among farmed chickens causing skeletal muscle infections, dermatitis, and septicaemia. The emergence of poultry-associated lineages has involved zoonotic transmission from humans to chickens but questions remain about the specific adaptations that promote proliferation of chicken pathogens. We characterized genetic variation in a population of genome-sequenced S. aureus isolates of poultry and human origin. Genealogical analysis identified a dominant poultry-associated sequence cluster within the CC5 clonal complex. Poultry and human CC5 isolates were significantly distinct from each other and more recombination events were detected in the poultry isolates. We identified 44 recombination events in 33 genes along the branch extending to the poultry-specific CC5 cluster, and 47 genes were found more often in CC5 poultry isolates compared with those from humans. Many of these gene sequences were common in chicken isolates from other clonal complexes suggesting horizontal gene transfer among poultry associated lineages. Consistent with functional predictions for putative poultry-associated genes, poultry isolates showed enhanced growth at 42 °C and greater erythrocyte lysis on chicken blood agar in comparison with human isolates. By combining phenotype information with evolutionary analyses of staphylococcal genomes, we provide evidence of adaptation, following a human-to-poultry host transition. This has important implications for the emergence and dissemination of new pathogenic clones associated with modern agriculture.

Characterization of Methicillin-Resistant Staphylococcus aureus Isolated from Healthy Turkeys and Broilers Using DNA Microarrays

Methicillin-resistant Staphylococcus aureus (MRSA) is a major human health problem and recently, domestic animals are described as carriers and possible reservoirs. Twenty seven S. aureus isolates from five turkey farms (n = 18) and two broiler farms (n = 9) were obtained by culturing of choana and skin swabs from apparently healthy birds, identified by Taqman-based real-time duplex nuc-mecA-PCR and characterized by spa typing as well as by a DNA microarray based assay which covered, amongst others, a considerable number of antibiotic resistance genes, species controls, and virulence markers. The antimicrobial susceptibility profiles were tested by agar diffusion assays and genotypically confirmed by the microarray. Five different spa types (3 in turkeys and 2 in broilers) were detected. The majority of MRSA isolates (24/27) belonged to clonal complex 398-MRSA-V. The most frequently occurring spa types were accordingly t011, t034, and t899. A single CC5-MRSA-III isolated from turkey and CC398-MRSA with an unidentified/truncated SCCmec element in turkey and broiler were additionally detected. The phenotypic antimicrobial resistance profiles of S. aureus isolated from both turkeys and broilers against 14 different antimicrobials showed that all isolates were resistant to ampicillin, cefoxitin, oxacillin, doxycycline, and tetracycline. Moreover, all S. aureus isolated from broilers were resistant to erythromycin and azithromycin. All isolates were susceptible to gentamicin, chloramphenicol, sulphonamides, and fusidic acid. The resistance rate against ciprofloxacin was 55.6% in broiler isolates and 42.1% in turkey isolates. All tetracycline resistant isolates possessed genes tetK/M. All erythromycin-resistant broiler isolates carried ermA. Only one broiler isolate (11.1%) carried genes ermA, ermB, and ermC, while 55.6% of turkey isolates possessed ermA and ermB genes. Neither PVL genes (lukF/S-PV), animal-associated leukocidin (lukM and luk-P83) nor the gene encoding the toxic shock syndrome toxin (tst1) were found in turkey and broiler isolates. In conclusion, the detection of MRSA in healthy turkeys and broilers with even additional antibiotic resistance markers is of major public health concern. The difference in antibiotic resistance and virulence markers between MRSA isolates from turkeys and broilers was addressed.

Prevalence of the Antibiotic Resistance Genes in Coagulase-Positive-and Negative-Staphylococcus in Chicken Meat Retailed to Consumers

The use of antibiotics in farm management (growing crops and raising animals) has become a major area of concern. Its implications is the consequent emergence of antibiotic resistant bacteria (ARB) and accordingly their access into the human food chain with passage of antibiotic resistance genes (ARG) to the normal human intestinal microbiota and hence to other pathogenic bacteria causative human disease. Therefore, we pursued in this study to unravel the frequency and the quinolone resistance determining region, mecA and cfr genes of methicillin-susceptible Staphylococcus aureus (MSSA), methicillin-resistant S. aureus (MRSA), methicillin-resistant coagulase-negative staphylococci (MRCNS) and methicillin-susceptible coagulase-negative staphylococci (MSCNS) isolated from the retail trade of ready-to-eat raw chicken meat samples collected during 1 year and sold across the Great Cairo area. The 50 Staphylococcus isolated from retail raw chicken meat were analyzed for their antibiotic resistance phenotypic profile on 12 antibiotics (penicillin, oxacillin, methicillin, ampicillin-sulbactam, erythromycin, tetracycline, clindamycin, gentamicin, ciprofloxacin, chloramphenicol, sulfamethoxazole-trimethoprim, and vancomycin) and their endorsement of the quinolone resistance determining region, mecA and cfr genes. The isolation results revealed 50 isolates, CPS (14) and CNS (36), representing ten species (S. aureus, S. hyicus, S. epidermedius, S. lugdunensis, S. haemolyticus, S. hominus, S. schleiferi, S. cohnii, S. intermedius, and S. lentus). Twenty seven isolates were methicillin-resistant. Out of the characterized 50 staphylococcal isolates, three were MRSA but only 2/3 carried the mecA gene. The ARG that bestows resistance to quinolones, β-lactams, macrolides, lincosamides, and streptogramin B [MLS(_B)] in MRSA and MR-CNS were perceived. According to the available literature, the present investigation was a unique endeavor into the identification of the quinolone-resistance-determining-regions, the identification of MRSA and MR-CNS from retail chicken meat in Egypt. In addition, these isolates might indicate the promulgation of methicillin, oxacillin and vancomycin resistance in the community and imply food safety hazards.

Comparative virulence studies and transcriptome analysis of Staphylococcus aureus strains isolated from animals

Several studies have been conducted to check the prevalence of methicillin-resistant strains of Staphylococcus aureus (MRSA) in animals and animal-derived food products but limited data are available regarding their virulence and associated gene expression profile. In the present study, antibiotic resistance and virulence of MRSA and methicillin-sensitive S. aureus animal isolates were determined in vitro by agar dilution, biofilm formation, adhesion, invasion and intracellular survivability assays. In addition, the pathogenicity of these isolates was examined in a murine model of S. aureus sepsis. MRSA1679a, a strain isolated from chicken, was observed to be highly virulent, in cell culture and in mouse model, and exhibited extensive resistant profile. Comparative gene expression profile of MRSA1679a and the reference human MRSA strain (ATCC 29213) was performed using Illumina-based transcriptome and RT-qPCR analyses. Several virulence elements including 22 toxin genes were detected in MRSA animal-isolate. In addition, we observed enhanced expression of crucial virulence regulators, such as sarA and KdpDE in MRSA animal-isolate compared to the human isolate. Collectively, gene expression profile including several virulence and drug-resistance factors confirmed the unique and highly virulent determinants of the MRSA strain of poultry origin which warrants further attention due to significant threat to public health.

Occurrence, Virulence Factors, Antimicrobial Resistance, and Genotyping of Staphylococcus aureus Strains Isolated from Chicken Products and Humans

Staphylococcus aureus in food is a consequence of inadequate hygienic handling and processing, posing a potential risk to public health. The current study aimed to characterize virulence factors, as well as antimicrobial resistance of Staphylococcus aureus and methicillin-resistant S. aureus (MRSA) isolated from retail chicken products and hand swabs from vendors in Egypt. In addition, genetic relatedness of the isolates from chicken and humans was evaluated by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) using protein A as a target. A total of 110 samples were collected from chicken products (n = 80) and vendors (n = 30). Overall, 30 (37.5%) chicken products samples were positive for S. aureus, whereas hand swabs from meat handlers revealed that 18 (60%) were positive. Ten MRSA strains were characterized by the presence of the mecA gene, comprising seven isolates from chicken and three from humans. Virulence-associated factors were evaluated by PCR, revealing that 31.3% of S. aureus isolates harbored the Panton-Valentine leukocidin (PVL) gene, whereas 10.4% were positive for the sea and sed genes each, and only two isolates were positive for γ-hemolysin-associated gene. Genotyping using spa PCR-RFLP showed identical restriction banding patterns of MRSA isolates of human and chicken meat origin, indicating the genetic relatedness of the isolates. To the best of our knowledge, this is the first study to characterize PVL-positive MRSA from chicken products and to utilize spa-RFLP for evaluating the genetic relatedness between MRSA of human and chicken origin in Egypt.