Antimicrobial resistance of old and recent Staphylococcus aureus isolates from poultry: first detection of livestock-associated methicillin-resistant strain ST398

A look at staphylococci from the one health perspective

Staphylococcus aureus and other staphylococcal species are resident and transient multihost colonizers as well as conditional pathogens. Especially S. aureus represents an excellent model bacterium for the "One Health" concept because of its dynamics at the human-animal interface and versatility with respect to host adaptation. The development of antimicrobial resistance plays another integral part. This overview will focus on studies at the human-animal interface with respect to livestock farming and to companion animals, as well as on staphylococci in wildlife. In this context transmissions of staphylococci and of antimicrobial resistance genes between animals and humans are of particular significance.

Analysis of Retrospective Laboratory Data on the Burden of Bacterial Pathogens Isolated at the National Veterinary Research Institute Nigeria, 2018-2021

Farm animals harbour bacterial pathogens, which are often viewed as important indicators of animal health and determinants of food safety. To better understand the prevalence and inform treatment, we audited laboratory data at the Bacteriology Laboratory of the NVRI from 2018-2021. Antibiotics were classified into seven basic classes: quinolones, tetracyclines, beta-lactams, aminoglycosides, macrolides, nitrofuran, and cephalosporins. Trends were analysed using a generalised linear model with a log link function for the Poisson distribution, comparing proportions between years with an offset to account for the variability in the total number of organisms per year. Avian (73.18%) samples were higher than any other sample. The major isolates identified were Escherichia. coli, Salmonella spp., Klebsiella spp., Staphylococcus spp., Proteus spp., and Pseudomonas spp. We found that antimicrobial resistance to baseline antibiotics increased over the years. Of particular concern was the increasing resistance of Klebsiella spp. to cephalosporins, an important second-generation antibiotic. This finding underscores the importance of farm animals as reservoirs of pathogens harbouring antimicrobial resistance. Effective biosecurity, surveillance, and frugal use of antibiotics in farms are needed because the health of humans and animals is intricately connected.

Development of Thermally Stable Nanobodies for Detection and Neutralization of Staphylococcal Enterotoxin B

In this study, sixteen unique staphylococcal enterotoxin B (SEB)-reactive nanobodies (nbs), including ten monovalent and six bivalent nbs, were developed. All characterized nbs were highly specific for SEB and did not cross-react with other staphylococcal enterotoxins (SE). Several formats of highly sensitive enzyme-linked immunosorbent assays (ELISAs) were established using SEB nbs and a polyclonal antibody (pAb). The lowest limit of detection (LOD) reached 50 pg/mL in PBS. When applied to an ELISA to detect SEB-spiked milk (a commonly contaminated foodstuff), a LOD as low as 190 pg/mL was obtained. The sensitivity of ELISA was found to increase concurrently with the valency of nbs used in the assay. In addition, a wide range of thermal tolerance was observed among the sixteen nbs, with a subset of nbs, SEB-5, SEB-9, and SEB-6², retaining activity even after exposure to 95 °C for 10 min, whereas the conventional monoclonal and polyclonal antibodies exhibited heat-labile properties. Several nbs demonstrated a long shelf-life, with one nb (SEB-9) retaining 93% of its activity after two weeks of storage at room temperature. In addition to their usage in toxin detection, eleven out of fifteen nbs were capable of neutralizing SEB's super-antigenic activity, demonstrated by their inhibition on IL-2 expression in an ex vivo human PBMC assay. Compared to monoclonal and polyclonal antibodies, the nbs are relatively small, thermally stable, and easy to produce, making them useful in applications for sensitive, specific, and cost-effective detection and management of SEB contamination in food products.

Multi-drug resistant ESKAPE pathogens and the uses of plants as their antimicrobial agents

Infections by ESKAPE (Enterococcus sp., Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp.) pathogens cause major concern due to their multi-drug resistance (MDR). The ESKAPE pathogens are frequently linked to greater mortality, diseases, and economic burden in healthcare worldwide. Therefore, the use of plants as a natural source of antimicrobial agents provide a solution as they are easily available and safe to use. These natural drugs can also be enhanced by incorporating silver nanoparticles and combining them with existing antibiotics. By focussing the attention on the ESKAPE organisms, the MDR issue can be addressed much better.

MRSA compendium of epidemiology, transmission, pathophysiology, treatment, and prevention within one health framework

Staphylococcus aureus is recognized as commensal as well as opportunistic pathogen of humans and animals. Methicillin resistant strain of S. aureus (MRSA) has emerged as a major pathogen in hospitals, community and veterinary settings that compromises the public health and livestock production. MRSA basically emerged from MSSA after acquiring SCCmec element through gene transfer containing mecA gene responsible for encoding PBP-2α. This protein renders the MRSA resistant to most of the β-lactam antibiotics. Due to the continuous increasing prevalence and transmission of MRSA in hospitals, community and veterinary settings posing a major threat to public health. Furthermore, high pathogenicity of MRSA due to a number of virulence factors produced by S. aureus along with antibiotic resistance help to breach the immunity of host and responsible for causing severe infections in humans and animals. The clinical manifestations of MRSA consist of skin and soft tissues infection to bacteremia, septicemia, toxic shock, and scalded skin syndrome. Moreover, due to the increasing resistance of MRSA to number of antibiotics, there is need to approach alternatives ways to overcome economic as well as human losses. This review is going to discuss various aspects of MRSA starting from emergence, transmission, epidemiology, pathophysiology, disease patterns in hosts, novel treatment, and control strategies.

Production systems and important antimicrobial resistant-pathogenic bacteria in poultry: a review

Economic losses and market constraints caused by bacterial diseases such as colibacillosis due to avian pathogenic Escherichia coli and necrotic enteritis due to Clostridium perfringens remain major problems for poultry producers, despite substantial efforts in prevention and control. Antibiotics have been used not only for the treatment and prevention of such diseases, but also for growth promotion. Consequently, these practices have been linked to the selection and spread of antimicrobial resistant bacteria which constitute a significant global threat to humans, animals, and the environment. To break down the antimicrobial resistance (AMR), poultry producers are restricting the antimicrobial use (AMU) while adopting the antibiotic-free (ABF) and organic production practices to satisfy consumers' demands. However, it is not well understood how ABF and organic poultry production practices influence AMR profiles in the poultry gut microbiome. Various Gram-negative (Salmonella enterica serovars, Campylobacter jejuni/coli, E. coli) and Gram-positive (Enterococcus spp., Staphylococcus spp. and C. perfringens) bacteria harboring multiple AMR determinants have been reported in poultry including organically- and ABF-raised chickens. In this review, we discussed major poultry production systems (conventional, ABF and organic) and their impacts on AMR in some potential pathogenic Gram-negative and Gram-positive bacteria which could allow identifying issues and opportunities to develop efficient and safe production practices in controlling pathogens.

Prevalence of methicillin-resistant Staphylococcus aureus in dairy farms: A systematic review and meta-analysis

Methicillin-resistant Staphylococcus aureus (MRSA) is an opportunistic bacterium that causes many human and animal infections worldwide. MRSA infections are classified as priority infections owing to their high morbidity and mortality, with a significant risk of zoonotic transmission. This study aimed to determine the pooled prevalence of MRSA in dairy cattle farms and its heterogeneity. Relevant studies were retrieved from three databases: PubMed, Web of Science, and Scopus. The pooled prevalence of MRSA in dairy farms was estimated using a random-effects model. Subgroup and meta-regression analyses were used to assess the probable sources of heterogeneity. Sensitivity and publication bias analyses were also performed. A total of 94 articles were eligible for inclusion in this meta-analysis. The pooled prevalence of MRSA was estimated to be 3.81% [95% confidence interval (95% CI) = 2.61-5.20] with significantly high heterogeneity (I ² = 96.6%, p = 0.00). For the subgroup analysis among continents, the prevalence was highest in Asia (4.89%; 95% CI = 2.88-7.35) and lowest in South America (1.33%, 95% CI = 0.00-5.49). As for the year of publication, MRSA prevalence was highest in reports published from 2015 to 2018 (4.36%, 95% CI = 2.41-6.80) and lowest in reports published before 2015 (2.65%, 95% CI = 0.75-5.52). As for sample type, the prevalence of MRSA in cattle milk (3.91%, 95% CI = 2.64-5.39) was higher than that in other sample types (1.19%, 95% CI = 0.05-3.24). These three factors were not significantly associated with the pooled prevalence of MRSA (p > 0.05). Therefore, the findings of this study indicate that the prevalence of MRSA has been minimal and consistent in dairy cattle farms over time.

Characterization of Staphylococcus aureus Isolates from Bovine Mastitis and Bulk Tank Milk: First Isolation of Methicillin-Susceptible Staphylococcus aureus in Japan

Staphylococcus aureus is one of the most important pathogens in humans as well as in livestock. Particularly, bovine mastitis caused by S. aureus is a serious issue in dairy farms due to disease recurrence. Here, cases of S. aureus-mediated intramammary infection occurring in the Miyagi Prefecture in Japan were monitored from May 2015 to August 2019; a total of 59 strains (49 from bovine milk and 10 from bulk milk) were obtained from 15 dairy farms and analyzed via sequence-based typing methods and antibiotic susceptibility tests. Two pairs of isolates were determined as recurrence cases from the same cows in distinct farms. The sequence type (ST), spa type, and coa type of each pair were the same: one pair showed ST705, t529, and VIb and the other showed ST352, t267, and VIc. In addition, the possession of toxin genes analyzed of each pair was exactly the same. Furthermore, seven oxacillin-sensitive clonal complex 398 isolates were obtained from a single farm. This is the first confirmed case of a Methicillin-Sensitive SA (MSSA) ST398 strain isolated from mastitis-containing cows in Japan. Our findings suggest that nationwide surveillance of the distribution of ST398 strains in dairy farms is important for managing human and animal health.

Synthesizing the connections between environmental disturbances and zoonotic spillover

Zoonotic spillover is a phenomenon characterized by the transfer of pathogens between different animal species. Most human emerging infectious diseases originate from non-human animals, and human-related environmental disturbances are the driving forces of the emergence of new human pathogens. Synthesizing the sequence of basic events involved in the emergence of new human pathogens is important for guiding the understanding, identification, and description of key aspects of human activities that can be changed to prevent new outbreaks, epidemics, and pandemics. This review synthesizes the connections between environmental disturbances and increased risk of spillover events based on the One Health perspective. Anthropogenic disturbances in the environment (e.g., deforestation, habitat fragmentation, biodiversity loss, wildlife exploitation) lead to changes in ecological niches, reduction of the dilution effect, increased contact between humans and other animals, changes in the incidence and load of pathogens in animal populations, and alterations in the abiotic factors of landscapes. These phenomena can increase the risk of spillover events and, potentially, facilitate new infectious disease outbreaks. Using Brazil as a study model, this review brings a discussion concerning anthropogenic activities in the Amazon region and their potential impacts on spillover risk and spread of emerging diseases in this region.

Methicillin-Resistant Staphylococcus aureus (MRSA) and Other Methicillin-Resistant Staphylococci and Mammaliicoccus (MRNaS) Associated with Animals and Food Products in Arab Countries: A Review

Simple Summary

Staphylococci are present in the microbiota of both humans and animal species, being recognized as the most important opportunistic pathogens. Antimicrobial resistance (AMR) has become a global public health issue presenting a significant risk because it severely limits treatment options. Methicillin resistance in staphylococci (MRS) poses a specific problem as it may cause serious human and animal infections, eventually resulting in death. The increasing observation of MRS in different animal species has raised the concern of their impact on animal health and the potential of zoonotic transmission. The availability of comprehensive data on the ecology and distribution of MRS in animals and food products worldwide is necessary to understand their relevance in the “One Health” domain. However, there is a gap in information in terms of MRS and the Arab countries. Therefore, our study aimed to provide an overview of the situation of MRS in these countries by reviewing the available data on livestock and animal products and making recommendations for the future.

Abstract

The prevalence of methicillin resistance in staphylococci has been increasing globally and is currently one of the major public health concerns. In particular, treating infections caused by staphylococci with acquired antimicrobial resistance is problematic, as their treatment is more difficult. The resistance is found both in human and animal staphylococcal strains. Methicillin-resistant staphylococci (MRS) have also been increasingly reported in wildlife. In Arab countries, MRS has been detected in food producing animals and food products; however, the risk this poses is somewhat unclear, and still a significant lack of information on the trend and distribution of these pathogens in these countries, which have a specific ecosystem (desert) and traditions (Muslim culture). In this manuscript, we aim to provide an overview of the prevalence and the major MRS clonal lineages circulating in these specific countries and compare to them other situations with different ecosystems and cultures.

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.

Molecular Diversity of Methicillin-Resistant and -Susceptible Staphylococcus aureus Detected in Animals: A Focus on Aquatic Animals

Staphylococcus aureus (S. aureus) are one of the best-known opportunistic pathogens capable of causing different types of infections in animals. Furthermore, it has the ability to acquire resistance to various antibiotics very easily. Methicillin-resistant S. aureus (MRSA) are currently of great concern as they are the leading cause of infections in humans and animals, with a major impact on health and the economy. Several studies already demonstrate that the spread of MRSA is constantly increasing due to its ability to form reservoirs in humans, animals and the environment. In fact, several works have already identified the presence of these bacteria in animals, including domestic animals, farm animals and even wild animals. Furthermore, the incidence of various S. aureus strains in aquatic animals has also been reported by different authors, although it is still a rarely discussed topic. Some of these strains have previously been associated with humans and other animals. Strain 398 is the strain that manages to infect a wider spectrum of hosts, having been identified in several different species. Aside from this strain, many others have yet to be identified. In addition, many of these strains have virulence factors and antibiotic resistance genes that worsen the situation. The present work is a review of studies that intend to investigate the epidemiology of this agent in samples of aquatic animals from different origins, in order to better understand its distribution, prevalence and the molecular lineages associated with these species.

Livestock-Associated Meticillin-Resistant Staphylococcus aureus—Current Situation and Impact From a One Health Perspective

Purpose of Review

In this article, we aim to provide an overview of the occurrence and characteristics of livestock-associated (LA-) meticillin-resistant Staphylococcus aureus (MRSA). We further question the role of LA-MRSA as a potential foodborne pathogen. We investigate recent findings and developments from a One Health perspective also highlighting current strategies and initiatives aiming to improve reporting, control, and prevention of LA-MRSA.

Recent Findings

While the overall number of invasive MRSA infections in humans is decreasing (in most European countries and the USA) or steadily increasing (in the Asia-Pacific region), the role of LA-MRSA as causative agent of invasive disease and as potential foodborne pathogen is still poorly understood. LA-MRSA prevalence in livestock remains high in many geographical regions and the acquisition of new virulence and resistance determinants constitutes a growing threat for human health.

Summary

The true incidence of LA-MRSA infections due to occupational exposure is unknown. Improved MRSA monitoring and tracking procedures are urgently needed. Strain typing is crucial to enable improved understanding of the impact of LA-MRSA on human and animal health.

In Vitro Antibacterial Effect of the Methanolic Extract of the Korean Soybean Fermented Product Doenjang against Staphylococcus aureus

Simple Summary

The emergence of bacterial antibiotic resistance is a negative phenomenon occurring worldwide in both animals and humans. The EU banned the use of antibiotic growth promoters in animal production, as their administration to livestock is assumed to substantially contribute to the spread of bacterial resistance. Therefore, alternatives to antibiotic substances are needed to maintain the quality and quantity of animal products. Certain plant materials, such as fermented soybean products, can serve as a source of substances with potential to decrease the growth of resistant bacteria, such as Staphylococcus aureus. Fermented soybean products, including doenjang, are known to contain natural phytoestrogens called isoflavones, which are especially interesting due to their antimicrobial activity; these products can also be utilized in animal feed. Thus, the antibacterial activity of the methanolic extract of the Korean soybean fermented product doenjang was evaluated using standardized microbiological methods against nine strains of resistant and sensitive S. aureus, including those occurring in animals. The extract has been shown to be active at a concentration range of 2048–4096 µg/mL against all tested S. aureus strains and can therefore serve as a promising alternative to antibiotics in animal feed after additional testing in the laboratory and on living animals.

Abstract

Ultra-high performance liquid chromatography/mass spectrometry showed soyasaponin I and the isoflavones daidzein, genistein, and glycitein to be the main components of the methanolic extract of the Korean soybean fermented product doenjang, which is known to be a rich source of naturally occurring bioactive substances, at average contents of 515.40, 236.30, 131.23, and 29.00 ng/mg, respectively. The antimicrobial activity of the methanolic extract of doenjang against nine Staphylococcusaureus strains was determined in vitro by the broth microdilution method to investigate its potential to serve as an alternative antibacterial compound. The results suggest that the extract is an effective antistaphylococcal agent at concentrations of 2048–4096 µg/mL. Moreover, the tested extract also showed the ability to inhibit the growth of both methicillin-sensitive and methicillin-resistant animal and clinical S. aureus isolates. The growth kinetics of the chosen strains of S. aureus at the minimum inhibitory concentration of the methanolic extract of doenjang support the idea that the tested extract acts as an antibacterial compound. To the best of our knowledge, this is the first report on the antistaphylococcal action of the methanolic extract of doenjang thus, additional studies including in vivo testing are necessary to confirm this hypothesis.

Genetic characterization of two methicillin-resistant Staphylococcus aureus spa type t127 strains isolated from workers in the dairy production chain in Greece

Methicillin-resistant Staphylococcus aureus (MRSA) constitutes a constant threat for the public health. Aim of the present study was to analyse the whole genome sequences of two MRSA strains belonging to Staphylococcus protein A (spa) type t127 isolated from humans working in two distantly located dairy production farms in Greece.MRSA strains were isolated from the nasal cavity of a food handler in a milk industry in Epirus, northwestern Greece (E-MRSA), and a person working in a cattle farm in Thrace, northeastern Greece (T-MRSA). Whole genome sequences taken using next generation sequencing were analysed for resistance and virulence genes applying various bioinformatic tools.Both isolates were assigned to ST1-IVa-t127 type, and they were transferring genes conferring resistance to tetracycline, β-lactams, and aminoglycosides; T-MRSA was carrying additional genes leading to macrolide, lincosamide and streptogramin B (MLSB) resistance. Both isolates were carrying three plasmid replicon types, rep5, rep7 and rep16, while T-MRSA harboured also rep10 and rep15. E-MRSA carried scn and sak genes which were absent from T-MRSA.In conclusion, the genetic characterization of two unrelated ST1-IVa-t127 MRSA strains isolated from humans in close contact with livestock in Greece can be used as basis for further epidemiological and evolutionary studies.

Antimicrobial Resistance Trends in Staphylococcus aureus Strains Carried by Poultry in North of Morocco: A Preliminary Analysis

The transmission of antibiotic resistance to human population through food consumption is a global public health threat. This study aimed to assess the nasopharyngeal carriage of S. aureus in poultry and to investigate antimicrobial susceptibility and virulence-associated genes. Nasopharyngeal swabs were collected from chickens at the slaughterhouse of Tangier and immediately transported to the microbiological laboratory for phenotypic identification and assessment of antibiotic susceptibility. The presence of 16S rRNA, nuc, mecA, mecC, Panton–Valentine leukocidin (PVL), and the toxic shock syndrome toxin 1 (TSST-1) genes were detected by PCR analysis for all isolates. Overall, 548 nasopharyngeal swabs were collected, of which 17 (3.4%) were S. aureus positive. More than half of the strains (54%) were resistant to penicillin, 29.4% to tetracycline, 23.5% to erythromycin, and 17% showed resistance to ciprofloxacin. The mecA and mecC were not identified in any of the recovered isolates. Of the S. aureus recovered, 29.41% of the isolates were found to be toxinogenic; 17.64% and 11.76% were positive for PVL and TSST-1 encoding genes, respectively. The trends of antibiotic resistance and the toxinogenic S. aureus carried by the poultry intended for consumption in Tangier present a huge concern. Preventive and containment measures should be implemented in order to limit the dissemination of resistance genes through the food chain and to reduce their increased rate.

Livestock-Associated Methicillin-Resistant Staphylococcus aureus and Related Risk Factors in Holdings of Veal Calves in Northwest Italy

Livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) have emerged worldwide as zoonotic pathogens. Data on LA-MRSA in veal calf production in Italy are lacking; the aim of this survey was to fill current knowledge gaps in its prevalence and characteristics. Between February 2012 and January 2013 nasal swabs were taken from 1650 three- to six-month-old veal calves on 55 farms in Piedmont (northwest Italy), including gathering-related epidemiological data. S. aureus were screened for methicillin resistance by phenotypic and molecular (mecA gene detection) methods. MRSA were further genotyped by multilocus sequence typing. About 30% of the herds tested positive for MRSA: three different clonal complexes (CC398, CC97, and CC1) and staphylococcal cassette chromosome mec types (IVa, IVb, and V) were detected. Multilevel logistic regression model indicated poor cleaning, importation from Austria, and animal age as risk factors and coagulase-negative staphylococci colonization as a predictive factor for the occurrence of MRSA. The detection of CCs circulating in pigs and dairy cattle in Italy underscores the ability of the LA-MRSA clones to spread among animal production systems. In addition to maintaining preventive control measures for human health, better cleaning procedures need to be implemented, especially after new calves have been introduced into the herd.

Species Distribution, Antimicrobial Resistance, and Enterotoxigenicity of Non-aureus Staphylococci in Retail Chicken Meat

Non-aureus staphylococci (NAS), including coagulase-negative staphylococci, have emerged as important causes of opportunistic infections in humans and animals and a potential cause of staphylococcal food poisoning. In this study, we investigated (i) the staphylococcal species profiles of NAS in in retail chicken meat, (ii) the phenotypic and genotypic factors associated with antimicrobial resistance in the NAS isolates, and (iii) the prevalence of classical and newer staphylococcal enterotoxin (SE) genes. A total of 58 NAS of nine different species were isolated from retail raw chicken meat samples. The occurrence of multidrug resistance in the NAS, particularly S. agnetis and S. chromogenes, with high resistance rates against tetracycline or fluoroquinolones were confirmed. The tetracycline resistance was associated with the presence of tet(L) in S. chromogenes and S. hyicus or tet(K) in S. saprophyticus. The occurrence of fluoroquinolone resistance in S. agnetis and S. chromogenes was usually associated with mutations in the quinolone resistance determining regions (QRDR) of gyrA and parC. In addition, the frequent presence of SE genes, especially seh, sej, and sep, was detected in S. agnetis and S. chromogenes. Our findings suggest that NAS in raw chicken meat can have potential roles as reservoirs for antimicrobial resistance and enterotoxin genes.

The first outbreak of methicillin-resistant Staphylococcus aureus in dairy cattle in Poland with evidence of on-farm and intrahousehold transmission

Staphylococcus aureus is a widely recognized pathogen responsible for many serious diseases in both humans and animals. It is also one of the major causative agents of bovine mastitis. Methicillin-resistant S. aureus (MRSA), although relatively rare in this pathology, has been increasingly reported in livestock animals, mainly in pigs, but also cattle, sheep, and poultry. The recent emergence of livestock-associated (LA-)MRSA is cause for an immediate public health concern due to the risk of zoonotic transmission to humans, and is of particular concern for people who work in animal husbandry or have prolonged contact with livestock animals. This study reports on the first LA-MRSA outbreak in dairy cattle and the first probable case of MRSA transmission between humans and cows in Poland. A single dairy farm located in Eastern Poland was monitored on a regular basis for the occurrence of mastitis. Over a 1-yr study period, 717 quarter-milk samples from 583 cows were collected and examined microbiologically. A total of 5 MRSA isolates from as many cows with subclinical mastitis were cultured. They all belonged to the same outbreak, given a 2-mo time window in which they were identified. During the outbreak, 24 oral and nasal swabs were voluntarily taken from 6 people: a milker, a veterinarian, and 4 members of the veterinarian's family. Eight swabs from a milker, veterinarian, and 2 family members yielded positive MRSA cultures. All MRSA isolates were genotyped with a combination of multiple-locus variable number tandem repeat analysis, multilocus sequence typing, and staphylococcal protein A gene (spa) typing. Eleven bovine (n = 5; 5 cases) and human (n = 6; 4 cases) isolates showed an identical drug-susceptibility profile and were indistinguishable upon multiple-locus variable number tandem repeat analysis (pattern A), multilocus sequence typing (ST398) and spa (t034) typing. The results of this study provide the evidence of transmission of MRSA between humans and cows, and between humans in the family setting. This work, despite being a preliminary investigation, underscores the risk of intra- and interspecies transmission of LA-MRSA and urges enhancement of the existing biosecurity measures aimed at preventing MRSA (and other milk pathogens) spread at both the farm- and household levels.

Simultaneous Detection of Three Foodborne Pathogens Based on Immunomagnetic Nanoparticles and Fluorescent Quantum Dots

This paper presents a peptide-mediated immunomagnetic separation technique and an immunofluorescence quantum dot technique for simultaneous and rapid detection of Escherichia coli O157:H7, Staphylococcus aureus, and Vibrio parahaemolyticus. First, three peptides that can specifically recognize the three foodborne pathogens were combined with magnetic nanoparticles to form an immunomagnetic nanoparticle probe for capturing three kinds of target bacteria and then added three quantum dot probes (quantum dots-aptamer), which formed a sandwich composite structure. When the three quantum dot probes specifically combined with the three pathogenic bacteria, the remaining fluorescent signal in the supernatant will be reduced by magnetic separation. Therefore, the remaining fluorescent signal in the supernatant can be measured with a fluorescence spectrophotometer to indirectly determine the three pathogens in the sample. The linear range of the method was 10-10⁷ cfu/mL, and in the buffer, the detection limits of E. coli O157:H7, S. aureus, and V. parahaemolyticus were 2.460, 5.407, and 3.770 cfu/mL, respectively. In the tap water simulation, the detection limits of E. coli O157:H7, S. aureus, and V. parahaemolyticus were 2.730, 1.990 × 10¹, and 4.480 cfu/mL, respectively. In the milk simulation sample, the detection limits of E. coli O157:H7, S. aureus, and V. parahaemolyticus were 6.660, 1.070 × 10¹, and 2.236 × 10¹ cfu/mL, respectively. The method we presented can detect three kinds of foodborne pathogens at the same time, and the entire experimental process did not exceed 4 h. It has high sensitivity and low detection limit and may be used in the sample detection of other pathogens.

Staphylococci in poultry intestines: a comparison between farmed and household chickens

Both pathogenic as well as nonpathogenic species of staphylococci have been reported in poultry, but these studies have not compared staphylococcal flora of both farmed and household broiler chickens. Staphylococci from farmed (n = 51) and household chicken intestines (n = 43) were isolated and tested for resistance to antimicrobials, presence of resistance genes, and inhibitory activity against other bacteria; correlation of resistance phenotype and genotype was also evaluated. At least 12 staphylococcal species were identified; Staphylococcus carnosus subspecies carnosus was the predominant species from both sources. Most farmed chicken staphylococci were resistant to tigecycline (38/51; 74.8%) while the highest level of resistance among the household chicken staphylococci was to clindamycin (31/43; 72.1%). The mecA gene was only detected in staphylococci from household chickens, whereas ermC and tetK or tetM were found in staphylococci from both groups of birds. Multidrug resistance (resistance ≥ 2 antimicrobial classes) was observed in 88% of resistant staphylococci ranging from 2 to 8 classes and up to 10 antimicrobials. Isolates produced inhibitory activity against 7 clinical bacterial strains primarily Enterococcus faecalis (25/88; 28.4%) and Escherichia coli (22/88; 25%). This study demonstrated that the staphylococcal population among farmed and household chickens varies by species and resistance to antimicrobials. These results may reflect the influence of the environment or habitat of each bird type on the intestinal microflora. As resistance in the staphylococci to antimicrobials used to treat human infections was detected, further study is warranted to determine strategies to prevent transfer of these resistant populations to humans via contamination of the poultry meat.

Characteristics of methicillin-resistant Staphylococcus aureus from broiler farms in Germany are rather lineage- than source-specific

Methicillin-resistant Staphylococcus aureus (MRSA) are a major concern for public health, and broiler farms are a potential source of MRSA isolates. In this study, a total of 56 MRSA isolates from 15 broiler farms from 4 different counties in Germany were characterised phenotypically and genotypically. Spa types, dru types, SCCmec types, and virulence genes as well as resistance genes were determined by using a DNA microarray or specific PCR assays. In addition, PFGE profiles of isolates were used for analysis of their epidemiological relatedness. While half of the isolates belonged to spa type t011, the other half was of spa types t1430 and t034. On 3 farms, more than 1 spa type was found. The most common dru type was dt10a (n = 19), followed by dt11a (n = 17). Susceptibility testing of all isolates by broth microdilution revealed 21 different resistance phenotypes and a wide range of resistance genes was present among the isolates. Up to 10 different resistance phenotypes were found on individual farms. Resistance to tetracyclines (n = 53), MLS_B antibiotics (n = 49), trimethoprim (n = 38), and elevated MICs of tiamulin (n = 29) were most commonly observed. Microarray analysis detected genes for leucocidin (lukF/S), haemolysin gamma (hlgA), and other haemolysines in all isolates. In all t1430 isolates, the egc cluster comprising of genes encoding enterotoxin G, I, M, N, O, U, and/or Y was found. The splitstree analysis based on microarray and PCR gene profiles revealed that all CC9/SCCmec IV/t1430/dt10a isolates clustered apart from the other isolates. These findings confirm that genotypic patterns were specific for clonal lineages rather than for the origin of isolates from individual farms.

Prevalence and characteristics of Livestock-Associated Methicillin-Resistant Staphylococcus aureus (LA-MRSA) isolated from chicken meat in the province of Quebec, Canada

This study was conducted to estimate the prevalence of Livestock-Associated Methicillin-Resistant Staphylococcus aureus (LA-MRSA) in retail chicken meat and broiler chickens from the Province of Quebec, Canada, and to characterize LA-MRSA isolates. A total of 309 chicken drumsticks and thighs were randomly selected in 2013 from 43 retail stores in the Monteregie. In addition, nasal swabs and caeca samples were collected in 2013-2014 from 200 broiler chickens of 38 different flocks. LA-MRSA was not detected in broiler chickens. Fifteen LA-MRSA isolates were recovered from four (1.3%) of the 309 chicken meat samples. Multi-Locus Sequence Typing (MLST) and SCCmec typing revealed two profiles (ST398-MRSA-V and ST8-MRSA-IVa), which were distinct using pulse-field gel electrophoresis (PFGE) and microarray (antimicrobial resistance and virulence genes) analyses. In addition to beta-lactam resistance, tetracycline and spectinomycin resistance was detected in all isolates from the 3 positive samples of the ST398 profile. Southern blot hybridization revealed that the resistance genes aad(D) and lnu(A), encoding resistances to aminoglycosides and lincosamides respectively, were located on plasmid. All isolates were able to produce biofilms, but biofilm production was not correlated with hld gene expression. Our results show the presence of two separate lineages of MRSA in retail chicken meat in Quebec, one of which is likely of human origin.

Citrox Improves the Quality and Shelf Life of Chicken Fillets Packed under Vacuum and Protects against Some Foodborne Pathogens

Natural antibacterial agents such as citrox are effective against many foodborne pathogens and foods contaminated with bacteria. We studied the antimicrobial effects of citrox solutions (1% and 2%) on the total viable counts of methicillin-resistant Staphylococcus aureus (MRSA) in chicken meat fillets. The total coliform group counts found in the chicken samples were also determined. The samples were treated with S. aureus at a concentration of 10⁶ colony-forming units (cfu)/g of meat and vacuum-packed (VP) at 4 °C for 3, 6, 9, 12, 15, 18, and 21 days. We also studied the effect of citrox on the total volatile basic nitrogen (TVBN) content and pH changes during the storage period of the meat samples. The results revealed that citrox inhibited the growth of MRSA in the chicken fillets. The total viable counts of MRSA decreased after treatment with 2% citrox in all treated samples that were stored at 4 °C by approximately 2 log units compared with the samples inoculated with S. aureus (Chicken-Staph groups) after 3, 6, 9, and 12 days of storage, and by approximately 1 log unit compared with the control samples treated with salt (Chicken-Salt groups) after 3, 6, and 9 days of storage. TVBN was reduced in the Chicken-Citrox-treated samples stored at 4 °C compared with the Chicken-Staph- and Chicken-Salt-treated samples. The results indicated that citrox is effective in reducing the total counts of MRSA and in improving the quality of chicken during the first three days of storage by reducing the number of bacteria by 1 log unit and extending the shelf life of chicken.

Prevalence of methicillin-resistant Staphylococcus aureus (MRSA) carriage and pattern of antibiotic resistance among sheep farmers from Southern Italy

PURPOSE

We conducted a cross-sectional study to measure the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) colonization, with a particular focus on livestock associated (LA)-MRSA in farmers working in contact with livestock (sheep) in one Italian region. Furthermore, we have assessed the antimicrobial resistance pattern of isolates and the association of carriage with specific characteristic of farms and working tasks.

PATIENTS AND METHODS

Demographic data, occupational history, and contact with animals information was collected. Nasal and oropharyngeal swabs were collected and all samples were tested for the isolation and identification of S. aureus. Isolates were examined for antimicrobial susceptibility and all MRSA strains underwent molecular analyses through multiple-locus variable number of tandem repeat analysis (MLVA).

RESULTS

A total of 115 sheep farms and 275 sheep farmers were enrolled. MRSA colonized workers were found in three farms; S. aureus was isolated in 97 workers (35.5%), whereas MRSA was isolated in 3 (1.1%) workers. All MRSA isolates were classified as multidrug resistant. Two of the MRSA isolates were resistant to quinupristin/dalfopristin (QDA), mupirocin, erythromycin, and tetracycline. Among methicillin-susceptible S. aureus (MSSA), 32 (34%) were resistant to tetracycline, 31 (33%) to erythromycin, 26 (27.6%) to QDA, and 22 (23.4%) to linezolid and clindamycin. One MRSA belonged to MLVA complex (MC) 001, found to colonize both humans and animals.

CONCLUSION

The picture of MRSA transmission among sheep farmers does not seem to be critical, although there is the need to improve adequate control measures to prevent and minimize any biological risk in sheep farms for both animal and human health. Specific monitoring/surveillance programs would help in better understanding the epidemiology of resistant strains.

Genotypes, Enterotoxin Gene Profiles, and Antimicrobial Resistance of Staphylococcus aureus Associated with Foodborne Outbreaks in Hangzhou, China

Staphylococcal food poisoning is an illness caused by the consumption of food that contains sufficient amounts of one or more enterotoxins. In the present study, a total of 37 S. aureus isolates were recovered from leftover food, swabs from a kitchen environment, and patient feces associated with four foodborne outbreaks that occurred in Hangzhou, southeast China, and were characterized by multilocus sequence typing (MLST), spa typing, pulse-field gel electrophoresis (PFGE), and antimicrobial susceptibility. Classical enterotoxin and enterotoxin-like genes were profiled by PCR analysis. ST6-t304 was the most common clone (40.54%), followed by ST2315-t11687 (32.43%). Six clusters (A to F) were divided based on PFGE patterns, and Clusters A and C were the most common types, constituting 86.49% of all isolates. Moreover, sea was the most frequently identified enterotoxin gene (81.08%), followed by the combination of seg-sei-selm-seln-sleo-selu and sec-sell (each 48.65%). Five isolates also harbored the exotoxin cluster sed-selj-ser. In addition, resistance to penicillin (97.30%), erythromycin (37.85), tetracycline (32.43%), clindamycin, gentamicin, and sulfamethoxazole (each 10.81%) was observed. Our research demonstrated the link between leftover foods and patients by molecular typing and detecting the profiles of enterotoxin or enterotoxin-like genes in human and food isolates. S. aureus maintains an extensive repertoire of enterotoxins and drug resistance genes that could cause potential health threats to consumers.

Nasal Colonization of Humans with Occupational Exposure to Raw Meat and to Raw Meat Products with Methicillin-Susceptible and Methicillin-Resistant Staphylococcus aureus

Livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) is widely disseminated as a nasal colonizer of conventionally raised livestock and of humans subjected to occupational exposure. Reports on contamination of raw meat raise the question as to whether occupationally exposed food handlers are at particular risk of nasal colonization by LA-MRSA. Here, we report the results from a cross-sectional study on nasal S. aureus/MRSA colonization of butchers, meat sellers, and cooks in Germany. We sampled 286 butchers and meat sellers in 26 butcheries and 319 cooks handling meat in 16 professional canteen kitchens. Swabs were processed on both blood agar plates and MRSA-selective plates. MRSA were confirmed by PCR for mec genes and by broth microdilution. All isolates were subjected to molecular typing. PCR for markers useful to differentiate human-adapted and animal-adapted subpopulations was performed due to the presence of clonal complexes known to occur in both livestock and humans (CC5, CC7, CC8, CC9, and CC398). Only two participants (0.33%) were colonized by MRSA (Hospital-associated MRSA ST22). Nasal colonization by methicillin-susceptible S. aureus (MSSA) was detected in 16.6% of cooks and in 26.2% of butchers and meat sellers. Among 16 of the isolates attributed to CC7, three were negative for the immune evasion gene cluster, suggesting an animal origin. Isolates attributed to CC5, CC8, and CC398 were negative for markers typical of animal-adapted subpopulations. The occupational handling of raw meat and raw meat products was not associated with nasal colonization by LA-MRSA.

Antimicrobial resistance and virulence genes of Streptococcus isolated from dairy cows with mastitis in China

Streptococcus is a major mastitis-causing pathogen in dairy cows. To investigate the prevalence, antimicrobial resistance and virulence gene of Streptococcus in mastitic milk, a total of 735 mastitic raw milk samples from dairy cows in 11 provinces of China were collected and tested. Antimicrobial resistance of Streptococcus isolates was determined by disc diffusion against 8 classes 29 antimicrobial agents, and Streptococcus resistant genes and virulence genes were determined by PCR and agarose gel electrophoresis. A total of 64 (8.71%) isolates of Streptococcus were isolated and identified using biochemical profiling, including 22 isolates of Streptococcus agalactiae, 13 isolates of Streptococcus dysgalactiae, and 29 isolates of Streptococcus uberis. Out of 64 resistant Streptococcus isolates, all isolates (100%) were resistant to 3 or more antimicrobials. The most frequency (n = 18, 28.12%) of the isolates were multi-resistant to 5-7 antimicrobials and the highest multi-resistant number was 29 (n = 1, 1.56%). Streptococcus isolates had the highest resistance rate to tetracycline (98.44%) and oxacillin (98.44%), followed by penicillin G (96.88%) and doxycycline (96.88%), and the lowest resistance was observed with respect to ciprofloxacin (1.56%). A total of 16 antimicrobials resistance genes with 25 combination patterns were detected in the isolates. The gene combination of Sul1/Sul2/Sul3 + gyrA/parC + cat1/cat2 was the most common pattern (12.5%). The correlation between resistant phenotypes and resistance genes in Streptococcs was 35.87%. A total of 7 virulence genes were detected and 59 (92.19%) isolates harbored at least one gene. Twenty-four classes of gene patterns were found in the isolates and the patterns of bca (9.38%) and cfb (9.38%) were the most prevalent form. In conclusion, the issue of drug resistance of Streptococcus is still a great concern in cattle health in China.

Phenotypic detection of methicillin-resistant Staphylococcus aureus in village chickens from poultry markets in Maiduguri, Nigeria

Objective:

The study was carried out to detect the carriage of methicillin-resistant Staphylococcus aureus (MRSA) and their antimicrobial susceptibilities in village chickens sold at Maiduguri poultry markets using phenotypic characterization.

Materials and Methods:

This was a cross-sectional study where 120 samples comprised 50% each of Nasal and cloacal swabs, were, respectively, collected from live village chickens sold at Maiduguri poultry markets and examined for the presence MRSA based on bacterial culture, biochemical characteristics, growth on oxacillin resistant screening agar base, and antimicrobial susceptibility tests.

Results:

The study revealed an overall occurrence of 38.33% S. aureus and 32.60% MRSA, respectively. Antimicrobial susceptibility test was carried out on MRSA positive isolates against seven antimicrobials. All the isolates (100%) exhibited resistance against cefoxitin, whereas the least antimicrobial resistance was recorded against erythromycin and streptomycin each with 26.6%, respectively. In the same way, the highest antibiotic susceptibility in this study was observed against erythromycin (60%) and least susceptibility was against vancomycin and streptomycin with 20% each. A varying intermediate antibiotic susceptibility ranging from 13.33% to 53.33% was observed. Multiple-drug resistance patterns were exhibited by MRSA isolates from this study with 73.3% of the isolates exhibiting resistance to two or more antibiotics.

Conclusion:

This study has shown the carriage of MRSA by village chickens which calls for serious public health concern and concludes that these birds might have acquired these pathogens from the environment or infected humans since they normally receive no less medical attention.

Characterisation of mecA gene negative Staphylococcus aureus isolated from bovine mastitis milk from Northern Germany

Staphylococcus aureus (S. aureus) is an important causative agent of contagious intermammary infections in dairy cattle. S. aureus is also considered as an important foodborne pathogen and cause of food poisoning cases and outbreaks worldwide. In order to understand the molecular ecology of S. aureus, the present study compared phenotypic and genotypic characteristics of 70 S. aureus isolates from bovine mastitis milk samples collected during the period from August 2001 to March 2014 in different regions of Northern Germany. The S. aureus isolates were characterised phenotypically, as well as genotypically for their genetic diversity using multi-locus sequence typing (MLST), spa typing and the presence of virulence genes encoding 16 staphylococcal enterotoxins (sea-selu), toxic shock syndrome toxin (tst), thermonuclease (nuc), clumping factor (clfA and clfB), coagulase (coa) and the methicillin resistance gene mecA. A total of 16 sequence types were grouped into eight clonal complexes (CCs), and 17 spa types were identified. These included six novel sequence types and one novel spa type. The majority of bovine mastitis milk-associated sequence types belonged to the clonal complex CC5, CC97, CC133, and CC151 and showed closely related genotypes or lineages with sequence types of human origin. The genotype CC133 (ST133-t1403) was predominant, constituting 27.1% of the isolates. In addition, the S. aureus isolates displayed nine different enterotoxigenic profiles. All S. aureus were methicillin-susceptible (MSSA). The current study provides new information on phenotypic and genotypic traits of S. aureus isolates from bovine mastitis. The comparison of characteristics of isolates from the present study originating from mastitis milk showed similarities with human isolates. This might help to better understand the distribution of S. aureus in the one health context.

Occurrence and Characterization of Methicillin Resistant Staphylococcus aureus in Processed Raw Foods and Ready-to-Eat Foods in an Urban Setting of a Developing Country

Infections by methicillin-resistant Staphylococcus aureus (MRSA) are gradually increasing in the community. In this study, we investigated a total of 162 food samples including 112 ready-to-eat (RTE) foods and 40 processed raw meat and fish samples collected from retail vendors in Dhaka, Bangladesh and determined the occurrence of toxigenic S. aureus and MRSA. Around 22% of samples were positive for S. aureus, RTE foods being more positive (23%) than the processed raw meat/fish samples (18%). Among 35 S. aureus isolates, 74% were resistant to erythromycin, 49% to ciprofloxacin and around 30% to oxacillin and cefoxitin. Around 37% of isolates were resistant to ≥3 classes of antibiotics and 26% of isolates (n = 9) were identified as MRSA. Majority of the isolates were positive for enterotoxin genes (74%), followed by pvl gene (71%), toxic shock syndrome toxin (tsst) gene (17%) and exfoliative toxin genes (11%). Multi locus sequence typing (MLST) of 9 MRSA isolates identified four different types such as ST80 (n = 3), ST6 (n = 2), ST239 (n = 2) and ST361 (n = 2). spa typing of MRSA isolates revealed seven different types including t1198 (n = 2), t315 (n = 2), t037 (n = 1), t275 (n = 1), t304 (n = 1), t8731 (n = 1) and t10546 (n = 1). To our knowledge, this is the first report entailing baseline data on the occurrence of MRSA in RTE foods in Dhaka highlighting a potential public health risk to street food consumers.

Methicillin-resistant Staphylococcus aureus: livestock-associated, antimicrobial, and heavy metal resistance

Staphylococcus aureus is an opportunistic pathogen of human and other mammals that is of increasing clinical and veterinary importance due to its ability to rapidly develop antimicrobial resistance. The injudicious use of antibiotics has given rise to the emergence of antibiotic resistant S. aureus strains, most importantly methicillin-resistant Staphylococcus aureus (MRSA). The emergence of livestock-associated MRSA (LA-MRSA) has highlighted the importance of directed research toward its prevention, as well as the need for the discovery and development of more efficient treatment than is currently available. Furthermore, the treatment of MRSA is complicated by the co-selection of heavy metal and antibiotic resistance genes by microorganisms. Livestock and livestock production systems are large reservoirs of heavy metals due to their use in feed as well as environmental contaminant, which has allowed for the selection of LA-MRSA isolates with heavy metal resistance. The World Health Organization reported that Africa has the largest gaps in data on the prevalence of antimicrobial resistance, with no reports on rates for LA-MRSA harboring heavy metal resistance in South Africa. This review aimed to report the emergence of LA-MRSA in South Africa, specifically the most frequent sequence type ST398, globally. Furthermore, we aimed to highlight the importance of LA-MRSA in clinical and food security, as well as this research gap in South Africa. This review sheds light on the prevalence of heavy metals in livestock farms and abattoirs, and focuses on the phenomenon of the co-selection of heavy metal and antibiotic resistance genes in MRSA, emphasizing the importance of a focused direction for research in humans, animals as well as environment using one-health approach.

Antimicrobial Resistance among Staphylococci of Animal Origin

Antimicrobial resistance among staphylococci of animal origin is based on a wide variety of resistance genes. These genes mediate resistance to many classes of antimicrobial agents approved for use in animals, such as penicillins, cephalosporins, tetracyclines, macrolides, lincosamides, phenicols, aminoglycosides, aminocyclitols, pleuromutilins, and diaminopyrimidines. In addition, numerous mutations have been identified that confer resistance to specific antimicrobial agents, such as ansamycins and fluoroquinolones. The gene products of some of these resistance genes confer resistance to only specific members of a class of antimicrobial agents, whereas others confer resistance to the entire class or even to members of different classes of antimicrobial agents, including agents approved solely for human use. The resistance genes code for all three major resistance mechanisms: enzymatic inactivation, active efflux, and protection/modification/replacement of the cellular target sites of the antimicrobial agents. Mobile genetic elements, in particular plasmids and transposons, play a major role as carriers of antimicrobial resistance genes in animal staphylococci. They facilitate not only the exchange of resistance genes among members of the same and/or different staphylococcal species, but also between staphylococci and other Gram-positive bacteria. The observation that plasmids of staphylococci often harbor more than one resistance gene points toward coselection and persistence of resistance genes even without direct selective pressure by a specific antimicrobial agent. This chapter provides an overview of the resistance genes and resistance-mediating mutations known to occur in staphylococci of animal origin.

Molecular Typing of ST239-MRSA-III From Diverse Geographic Locations and the Evolution of the SCCmec III Element During Its Intercontinental Spread

ST239-MRSA-III is probably the oldest truly pandemic MRSA strain, circulating in many countries since the 1970s. It is still frequently isolated in some parts of the world although it has been replaced by other MRSA strains in, e.g., most of Europe. Previous genotyping work (Harris et al., 2010; Castillo-Ramírez et al., 2012) suggested a split in geographically defined clades. In the present study, a collection of 184 ST239-MRSA-III isolates, mainly from countries not covered by the previous studies were characterized using two DNA microarrays (i) targeting an extensive range of typing markers, virulence and resistance genes and (ii) a SCCmec subtyping array. Thirty additional isolates underwent whole-genome sequencing (WGS) and, together with published WGS data for 215 ST239-MRSA-III isolates, were analyzed using in-silico analysis for comparison with the microarray data and with special regard to variation within SCCmec elements. This permitted the assignment of isolates and sequences to 39 different SCCmec III subtypes, and to three major and several minor clades. One clade, characterized by the integration of a transposon into nsaB and by the loss of fnbB and splE was detected among isolates from Turkey, Romania and other Eastern European countries, Russia, Pakistan, and (mainly Northern) China. Another clade, harboring sasX/sesI is widespread in South-East Asia including China/Hong Kong, and surprisingly also in Trinidad & Tobago. A third, related, but sasX/sesI-negative clade occurs not only in Latin America but also in Russia and in the Middle East from where it apparently originated and from where it also was transferred to Ireland. Minor clades exist or existed in Western Europe and Greece, in Portugal, in Australia and New Zealand as well as in the Middle East. Isolates from countries where this strain is not epidemic (such as Germany) frequently are associated with foreign travel and/or hospitalization abroad. The wide dissemination of this strain and the fact that it was able to cause a hospital-borne pandemic that lasted nearly 50 years emphasizes the need for stringent infection prevention and control and admission screening.

Carriage Methicillin-Resistant Staphylococcus aureus in Poultry and Cattle in Northern Algeria

Multiresistant and especially Methicillin-Resistant Staphylococcus aureus (MRSA) poses a serious public health problem that requires their immediate identification and antibiotic resistance characteristics. In order to determine antibiotic resistance S. aureus poultry and bovine origin, 8840 samples were collected from slaughterhouses in the northern region of Algeria between years 2009 and 2014. 8375 samples were from an avian origin (1875 from laying hens and 6500 from broiler chickens) and the rest was from bovine origin. Bacteriological isolation and identification were made by classical culture method and antibiotic resistance patterns were determined by disc diffusion test. The prevalence of S. aureus was 42% in laying hens, 12% in broilers, and 55% in bovine samples. The prevalence of MRSA was 57%, 50%, and 31% in laying hens, broiler chickens, and bovine, respectively. While MRSA strains isolated from poultry showed cross-resistance to aminoglycosides, fluoroquinolones, macrolides, sulphonamides, and cyclins, those isolated from bovine also revealed similar multiresistance except for sulphonamide. This high percentage of methicillin resistance and multidrug resistance in S. aureus poultry and bovine origin may have importance for human health and curing of human infections.

Association Between the Methicillin Resistance of Staphylococcus aureus Isolated from Slaughter Poultry, Their Toxin Gene Profiles and Prophage Patterns

In this work, 85 strains of Staphylococcus aureus were isolated from samples taken from slaughter poultry in Poland. Attempts were made to determine the prophage profile of the strains and to investigate the presence in their genome of genes responsible for the production of five classical enterotoxins (A–E), toxic shock syndrome toxin (TSST-1), exfoliative toxins (ETA and ETB) and staphylokinase (SAK). For this purpose, multiplex PCR was performed using primer-specific pairs for targeted genes. The presence of the mecA gene was found in 26 strains (30.6%). The genomes of one of the methicillin-resistant S. aureus (MRSA) strains and two methicillin-sensitive S. aureus (MSSA) strains contained the gene responsible for the production of enterotoxin A. Only one MRSA strain and two MSSA strains showed the presence of the toxic shock syndrome toxin (tst) gene. Only one of the MSSA strains had the gene (eta) responsible for the production of exfoliative toxins A. The presence of the staphylokinase gene (sak) was confirmed in 13 MRSA strains and in 5 MSSA strains. The study results indicated a high prevalence of prophages among the test isolates of Staphylococcus aureus. In all, 15 prophage patterns were observed among the isolates. The presence of 77-like prophages incorporated into bacterial genome was especially often demonstrated. Various authors emphasize the special role of these prophages in the spread of virulence factors (staphylokinase, enterotoxin A) not only within strains of the same species but also between species and even types of bacteria.

Variability of SCCmec elements in livestock-associated CC398 MRSA

The most common livestock-associated lineage of methicillin-resistant Staphylococcus aureus (MRSA) in Western Europe is currently clonal complex (CC) 398. CC398-MRSA spread extensively across livestock populations in several Western European countries, and livestock-derived CC398-MRSA strains can also be detected in humans. Based on their SCCmec elements, different CC398 strains can be distinguished. SCCmec elements of 100 veterinary and human CC398-MRSA isolates from Germany and Austria were examined using DNA microarray-based assays. In addition, 589 published SCC and/or genome sequences of CC398-MRSA (including both, fully finished and partially assembled sequences) were analysed by mapping them to the probe sequences of the microarrays. Several isolates and sequences showed an insertion of a large fragment of CC9 genomic DNA into the CC398 chromosome. Fifteen subtypes of SCCmec elements were detected among the 100 CC398 isolates and 41 subtypes could be discerned among the published CC398 sequences. Eleven of these were also experimentally detected within our strain collection, while four subtypes identified in the isolates where not found among the sequences. A high prevalence of heavy metal resistance genes, especially of czrC, was observed among CC398-MRSA. A possible co-selection of resistances to antibiotics and zinc/copper supplements in animal feed as well as a spill-over of SCCmec elements that have evolved in CC398-MRSA to other, possibly more virulent and/or medically relevant S. aureus lineages might pose public health problems in future.

Basis of Virulence in Enterotoxin-Mediated Staphylococcal Food Poisoning

The Staphylococcus aureus enterotoxins are a superfamily of secreted virulence factors that share structural and functional similarities and possess potent superantigenic activity causing disruptions in adaptive immunity. The enterotoxins can be separated into two groups; the classical (SEA-SEE) and the newer (SEG-SElY and counting) enterotoxin groups. Many members from both these groups contribute to the pathogenesis of several serious human diseases, including toxic shock syndrome, pneumonia, and sepsis-related infections. Additionally, many members demonstrate emetic activity and are frequently responsible for food poisoning outbreaks. Due to their robust tolerance to denaturing, the enterotoxins retain activity in food contaminated previously with S. aureus. The genes encoding the enterotoxins are found mostly on a variety of different mobile genetic elements. Therefore, the presence of enterotoxins can vary widely among different S. aureus isolates. Additionally, the enterotoxins are regulated by multiple, and often overlapping, regulatory pathways, which are influenced by environmental factors. In this review, we also will focus on the newer enterotoxins (SEG-SElY), which matter for the role of S. aureus as an enteropathogen, and summarize our current knowledge on their prevalence in recent food poisoning outbreaks. Finally, we will review the current literature regarding the key elements that govern the complex regulation of enterotoxins, the molecular mechanisms underlying their enterotoxigenic, superantigenic, and immunomodulatory functions, and discuss how these activities may collectively contribute to the overall manifestation of staphylococcal food poisoning.

A Novel Methicillin-Resistant Staphylococcus aureus t11469 and a Poultry Endemic Strain t002 (ST5) Are Present in Chicken in Ebonyi State, Nigeria

Background

The changing epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) from a hospital-associated pathogen to an organism commonly found in the community and in livestock reflects an organism well-equipped to survive in diverse environments and adjust to different environmental conditions including antimicrobial use.

Methods

We investigated the molecular epidemiology of S. aureus and MRSA in poultry in Ebonyi State, Nigeria. Samples were collected from 1800 birds on 9 different farms within the state. Positive isolates were tested for antibiotic susceptibility and molecular typing.

Results

Prevalence in birds was 13.7% (247/1800). MRSA prevalence in poultry was 0.8%. The prevalence of MRSA in broilers and layers was 1.2% and 0.4%, respectively. All tested isolates were susceptible to vancomycin. Molecular analysis of the isolates revealed 3 spa types: t002, t084, and a novel spa type, t11469. The novel spa type t11469 belonged to sequence type ST5.

Conclusion

The detection of t002 in chicken suggests the presence of livestock-associated MRSA in poultry in Ebonyi State. The detection of the new spa type t11469 in poultry that has not been characterised to ascertain its pathogenic potential remains a cause for concern, especially as some were found to carry PVL genes, a putative virulence factor in staphylococcal infection.

Antimicrobial policies in animals and human health

This invited commentary aims to highlight 3 recommendations to rationalize antimicrobial consumption in livestock, in order to minimize the spread of resistant bacteria and simultaneously safeguarding animal and public health.

Longitudinal study of Staphylococcus aureus colonization and infection in a cohort of swine veterinarians in the United States

Background

People working with pigs are at elevated risk of harboring methicillin resistant S. aureus (MRSA) in their nose, which is attributable to occupational exposure to animals harboring livestock adapted S. aureus. To obtain insight into the biological nature of occupationally related nasal culture positivity, we conducted a longitudinal study of 66 swine veterinarians in the USA.

Methods

The study cohort resided in 15 US states and worked predominantly with swine. Monthly for 18 months, participants self-collected nasal swabs and completed a survey to report recent exposure to pigs and other animals; the occurrence of work related injuries; and any relevant health events such as skin and soft tissue infections or confirmed staphylococcal infections. Nasal swabs were cultured using selective methods to determine the presence of MRSA and methicillin susceptible S. aureus (MSSA), and isolates were characterized by spa typing and MLST.

Results

Prevalences of S. aureus (64%, monthly range from 58 to 82%) and MRSA (9.5%; monthly range from 6 to15%) were higher than reported for the US population (30% and 1.5% respectively). Predominant spa types were t034 (ST398, 37%), t002 (ST5, 17%) and t337 (ST9/ST398 13%), a distribution similar to that found in a concurrent study in pigs in the USA. Veterinarians were classified into three groups: Persistent carriers (PC, 52%), Intermittent carriers (IC, 47%) and Non-carriers (NC, 1%). Persistent carriage of a single spa type was observed in 14 (21%) of participants, and paired (first and last) isolates from PC subjects had minor genetic differences. Swabs from PC veterinarians carried higher numbers of S. aureus. Among IC veterinarians, culture positivity was significantly associated with recent contact with pigs.

Conclusions

Exposure to pigs did not lead to prolonged colonization in most subjects, and the higher numbers of S. aureus in PC subjects suggests that unknown host factors may determine the likelihood of prolonged colonization by S. aureus of livestock origin. Exposure to S. aureus and persistent colonization of swine veterinarians was common but rarely associated with S. aureus disease.

Electronic supplementary material

The online version of this article (10.1186/s12879-017-2802-1) contains supplementary material, which is available to authorized users.

MRSA in Pig Population

Methicillin resistant Staphylococcus aureus (MRSA) is widespread worldwide in different types of animal species and as a zoonosis takes a great risk for human health not only as a food toxicoinfection, but also as a highly resistant pathogen causing serious soft tissue infectious, septicaemia and even death. One of the most affected food-producing animal species is swine in the production of which new antibiotics in big amounts are used more and more continuously, increasing antimicrobial resistance. In this study several commercial pig farms and pigs with different age groups as well as farm workers and samples from environment were examined with the purpose of detecting MRSA prevalence and evaluating antimicrobial resistance. A total of 85 isolated MRSA strains were characterised by conventional microbial and molecular methods. MRSA was found in all farms. MRSA prevalence in different pig age groups and farms varied from none to 79.2% reaching higher values among 3-3.5 (26.6%) and 4-4.5 (31.9%) old pigs. The 98.7% of 74 further investigated MRSA isolates were resistant to penicillin, 94.9% to tetracycline, 45.6% to cephalexin and 10 different spa types were found among which spa type t011 was the most widespread. To the best of our knowledge, this is the first time MRSA was researched in sow milk and the first description of the presence of MRSA in several age groups of pigs in Latvia.

Presence of Methicillin-resistant Staphylococcus Aureus in Slaughterhouse Environment, Pigs, Carcasses, and Workers

Introduction

Methicillin-resistant Staphylococcus aureus (MRSA) is a highly resistant and difficult to cure zoonotic microorganism, which makes up a large part of food toxic infections and has shown high prevalence among pig population all over the world. The aim of the study was to establish the occurrence of MRSA in slaughterhouses, evaluate its antimicrobial resistance, and verify whether there are any differences or similarities with reference to other European countries.

Material and Methods

A total of 100 pigs, 105 carcasses, 19 workers, and 24 samples from the environment of several slaughterhouses were examined by conventional microbial and molecular methods.

Results

In total, 78 MRSA isolates were found. MRSA prevalence in slaughtered pigs varied from 8.0% to 88.6% depending on the slaughterhouse, reaching higher prevalence in slaughterhouses with higher slaughter capacity. In total, 21.1% of all workers were carriers of MRSA and 6.7% of carcasses were contaminated with MRSA. The 98.2% of MRSA isolates were resistant to penicillin, 89.1% to tetracycline, 60.1% to erythromycin, 65.5% to gentamycin, and 15 different spa types were found, among which spa type t01333 was most widespread.

Conclusion

The study indicated that MRSA prevalence and spa types differed according to slaughterhouse slaughter capacity and good hygiene practices. Quite high MRSA occurrence among slaughterhouse workers is one of the main factors which increase pork contamination risk.

Prevalence of methicillin-resistant Staphylococcus aureus (MRSA) in retail food in Singapore

We characterised 227 Staphylococcus aureus isolates from retail food and food handlers’ gloves samples obtained through food surveillance and risk assessment studies between 2011 and 2014. Of 227 isolates, five (2.2%) were methicillin-resistant and belonged to sequence types ST80 (n = 3) and ST6 (n = 2). All five isolates belonged to SCCmec type IV, were Panton-Valentine leukocidin (pvl)-negative and staphylococcal enterotoxin genes-positive. Resistance to azithromycin was found in ST80 isolates, in addition to resistance to beta-lactams. Our finding of two clinically relevant methicillin-resistant S. aureus (MRSA) strains (ST80 and ST6) in ready-to-eat food and food contact surfaces at retail in Singapore suggests food and food contact surfaces as potential environmental sources of MRSA in the community.

Characterization of Staphylococcus aureus in Goose Feces from State Parks in Northeast Ohio

Staphylococcus aureus can colonize a range of species. Although numerous studies have isolated pathogenic bacteria from wild birds, very little is known regarding S. aureus and their potential to spread methicillin-resistant (MRSA) strains. The objective of this study was to determine the presence and molecular characteristics of S. aureus in geese fecal samples collected from ten state parks across Northeast Ohio (NEO). A total of 182 fecal samples from Canada geese (Branta canadensis) were collected in April 2015. Isolates were characterized using multi-locus sequence (MLST) and spa typing, as well as PCR to detect the presence of Panton-Valentine leukocidin (PVL), mecA, and scn genes. Antibiotic susceptibility testing was done via Vitek-2 system. The overall contamination by S. aureus in fecal samples was 7.1% (13/182); 7/182 (3.8%) were MRSA and 6/182 (3.3%) were methicillin-susceptible S. aureus (MSSA). One isolate was positive for PVL. A total of eight different spa types were observed. MLST included ST5, ST8, ST291, ST298, and ST2111. One (7.7%) MSSA isolate was multi-drug resistant. The S. aureus contamination in NEO state parks ranged from 0% (park 1, 4, 8, 9) to 35% (7/20) (park 5). Parks 2, 3, 6, and 7 had 5% (1/20) positive. The results of this study indicate that the feces of geese collected at various state parks in NEO may harbor S. aureus.

Genetic characterisation of antimicrobial resistance and virulence genes in <i>Staphylococcus aureus</i> isolated from commercial broiler chickens in the Durban metropolitan area, South Africa

Antimicrobial resistance of Staphylococcus aureus in human and veterinary medicine is a serious worldwide problem. The aim of this study was to investigate the prevalence of S. aureus in commercial broiler chickens as well as to establish antimicrobial susceptibility and the distribution of genetic determinants conferring resistance and virulence. One hundred and ninety-four samples were aseptically collected from broiler chicken slaughterhouses and retail outlets around the Durban metropolitan area in South Africa. Microbiological and molecular methods were used to detect the presence of S. aureus as well as its resistance- and virulence-associated genes. Polymerase chain reaction (PCR) was used to confirm the presence of S. aureus by amplifying the nuc gene. Approximately 54% of 194 samples were positive for S. aureus. The disc diffusion technique was used to investigate antimicrobial susceptibility profiles of the S. aureus isolates to a battery of 10 antimicrobial agents, namely ampicillin, chloramphenicol, gentamicin, erythromycin, cefoxitin, kanamycin, streptomycin, tetracycline, vancomycin and trimethoprim. The results demonstrated that S. aureus isolates of abattoir origin had a high level (79.4%) of resistance to tetracycline, followed by ampicillin, vancomycin, cefoxitin, trimethoprim, erythromycin and streptomycin with resistance rates of 65.1%, 61.9%, 60.3%, 58.7%, 57.1% and 46.0%, respectively. Staphylococcus aureus isolates of retail origin exhibited higher antimicrobial resistance prevalence rates than those of abattoir origin. Tetracycline had the highest resistance rate (100%), followed by cefoxitin (91.7%), erythromycin (83.3%), streptomycin (83.3%) and kanamycin (66.7%). All isolates were resistant to two or more antimicrobial agents. Out of the four virulence genes that were screened, only two were detected (coagulase and protein A); however, their prevalence rates were very low. All antimicrobial resistance genes screened were detected (mecA, BlaZ and tetK), although their prevalence did not correspond with antimicrobial susceptibility testing.