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

Assessing antibiotic residue presence in Turkey meat: insights from a four-box method analysis

Contemporary poultry farming involves extensive antibiotic use, which could potentially pose health risks to consumers through antibiotic residues in animal-derived food products, especially meat. Recent decisions, particularly the ban on nearly all antibiotic feed additives utilized as growth promoters, have resulted in a decrease in their usage. Nonetheless, their essential role in therapy and their economic value are indisputable. This study evaluated the presence of antibiotic residues in marketed turkey meat using the four-box method. The analyses indicated that, of the 400 samples examined, the overall prevalence of contamination was 65.75%. Among the different types of antibiotics identified in the samples, β-lactam/tetracycline residues were the highest, with a prevalence of 41.44%. The analysis of different sample types revealed significant contamination rates in turkey organs, particularly the liver, with a contamination prevalence of approximately 83.75%, and the wing muscle, 78.75%. Two antibiotic families, β-lactam and tetracycline, were identified in the wing muscle and liver at frequencies of 44.44% and 43.28%, respectively. Regarding cross-contamination, positive samples exhibited contamination concurrently by a specific type of residue, with a notable rate of 58.19%. All analyzed organs exhibited contamination by multiple residue types, with varying contaminants present in different organs. The findings indicated varying detection rates of antibiotic residues in consumed turkey meat. These highlight the excessive use of antibiotics in the poultry industry, increasing consumer exposure to these residues'associated risks. Therefore, it is essential to implement stricter measures and monitoring systems regarding the use of antibiotics in poultry farming.

Prevalence of MRSA in Livestock, Including Cattle, Farm Animals, and Poultry, in Mainland China, Hong Kong Special Administrative Region, Sri Lanka, and Bangladesh: A Systematic Review and Meta-Analysis

Methicillin-resistant Staphylococcus aureus (MRSA) can spread from animals to humans, but how it adapts to infect both is not fully understood. Our review aimed to determine the prevalence of MRSA in livestock, poultry, and companion animals in different countries, including Bangladesh, the Hong Kong SAR, Mainland China, and Sri Lanka. Articles were collected using PubMed, Embase, Web of Science, Scopus, CINAHL, and Google Scholar. Only prevalence studies that followed the PICO guidelines were included. A random-effects model meta-analysis was used to pool the data. The quality of the evidence and bias were assessed using the GRADEpro and Cochrane collaboration tools. Out of 1438 articles, 69 studies were eligible for meta-analysis. The studies showed significant heterogeneity (I2 = 97.00%, p < 0.0001) in the prevalence of MRSA colonization. Therefore, a random-effects model was used to determine the pooled prevalence of MRSA colonization, which was found to be 4.92% (95% CI: 3.79% to 6.18%). Begg's test (p = 0.0002) and Egger's test (p = 0.0044) revealed publication bias. Subgroup analysis of the pooled prevalence of MRSA showed a significant difference (p < 0.00001) when the subgroups were divided by country, MRSA detection method, whether pre-enrichment was performed or not, study period, sample collection location, and study population. Although significant factors can partially explain the heterogeneity, it is crucial to recognize the heterogeneity within different subgroups. The pooled prevalence of MRSA was found to vary significantly (p < 0.00001) among the study periods and has increased since the study period of 2020. Therefore, it is crucial to continuously monitor and implement measures to control the spread of MRSA in animals to minimize the risk of transmission to humans.

Methicillin-Resistant S. aureus Carrying the PVL and Toxic Shock Syndrome Toxin in Healthy Dogs in Algeria

Background/Objectives: Staphylococcus aureus and Staphylococcus pseudintermedius are major opportunistic pathogens in both humans and dogs. In pets, the dissemination of methicillin-resistant isolates (MRSA or MRSP) is problematic for the treatment of animals and is a public health issue due to their zoonotic potential. MRSA and MRSP may also harbor virulent genes that increase their dangerousness. This study aimed to assess the prevalence of (MR)SA and (MR)SP in healthy dogs and their owners in Algeria. Methods: Swabs were collected from various body sites of healthy dogs (n = 88) and from the nose of their owners (n = 38). Antimicrobial susceptibility testing was performed by antibiograms according to the disc diffusion method, and clonality was assessed using Pulsed-Field Gel Electrophoresis (PFGE). All methicillin-resistant isolates were short-read whole-genome sequenced using the Illumina technology. Results: 26 S. aureus and 17 S. pseudintermedius isolates were respectively collected from 13 dogs (13/88, 14.8%). No MRSP isolate was detected, while MRSA was found in six dogs (6.8%). Isolates belonged to ST1 (n = 3), ST 80 (n = 1), and ST 22 (n = 2, including the single-locus variant ST7118). All MRSA displayed the immune evasion cluster (IEC) type E. The ST80 isolate presented the Panton-Valentine toxin, and the ST22/ST7118 isolates carried the tst gene coding for the toxic shock syndrome toxin. Conclusions: The epidemiology of MRSA in healthy Algerian dogs mirrors the one in Algerian people. This poses a zoonotic and public health concern due to the virulence and resistance genes displayed by these isolates. Our results indicate the need for developing One Health strategies to avoid a large-scale dissemination of MRSA in Algerian dogs.

Spread of livestock-associated methicillin-resistant Staphylococcus aureus in poultry and its risks to public health: A comprehensive review

The livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) strains are prevalent in the poultry farming environment and are a common component of the bacterial microbiota on the skin and mucous membranes of healthy animals. The origin and spread of LA-MRSA are attributed to the use of antibiotics in animals, and close contact between people and different animal species increases the risk of animal exposure to humans. The epidemiology of LA-MRSA in poultry significantly changed when ST398 and ST9 were found in food-producing animals. The significance of LA-MRSA and zoonotic risk associated with handling and processing foods of avian origin is highlighted by the LA-MRSA strain's ability to infect chickens. People who work with poultry are more prone to contract LA-MRSA than the general population. There is scientific consensus that individuals who have close contact with chickens can become colonized and subsequently infected with LA-MRSA; these individuals could include breeders, medical professionals, or personnel at chicken slaughterhouses. The prevention of LA-MRSA infections and diseases of poultry origin requires taking precautions against contamination across the entire chicken production chain.

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

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

Pathogenomic profile and clonal diversity of potential zoonotic MRSA-CC7-ST789-t091-SCCmecV from human skin and soft tissue infections

The whole genome sequence (WGS) of prevalent MRSA strains harboring mecA gene obtained from skin and soft tissue infections (SSTIs) in Nigerian hospitals were profiled for pathogenomic structure and evaluated for clonal diversity. The two MRSA strains identified among 66 isolated multi-drug resistant S. aureus from a collection of 256 clinical samples were phenotyped for antibiotic resistance and genotyped for mecA, SCCmec, and spa types. The mecA positive MRSA was analysed using whole-genome sequencing for resistomes, virulomes, phylogenomic profiles and clonal diversity. The identified MRSA-CC7-ST789-t091-SCCmecV strains from a female child (aged 1 year) with severe otorrhea and an adult male (aged 23) with purulent wound abscess showed high-level resistance to streptomycin, vancomycin, kanamycin, sulfamethoxazole and ciprofloxacin. Both strains harbored abundant resistomes, inherent plasmids, chromosomal replicons and typical seven housekeeping genes (arc3, aroE4, glpF1, gmk4, pta4, tpi6, yqiL3). The most abundant putative virulomes were pathogenesis-associated proteins (included hemolysin gamma, leucocidins, proteases, staphylococcal superantigen/enterotoxin-like genes (Set/Ssl), capsule- and biofilm-associated genes, and hyaluronate lyase). Comparative phylogenomic analysis revealed the relatedness of the two clonal strains with prevalent MRSA-CC7 pathotypes observed in Italy (2013 and 2014), Denmark (2014), Thailand (2015 and 2016), USA (2018), and Nigeria (2016 and 2020); and share high genetic similarities with livestock strains from cow milk and cattle. Identified MRSA-CC7-ST789-t091-SCCmecV pathotypes implicated in SSTIs from Nigeria harboring repertoires of antibiotic resistance and virulence genes, and genetic relatedness with livestock strains; show the possibility of gene transfer between animal and human. Adequate hospital MRSA infection control and geno-epidemiological surveillance for animal and human transfer is required.

Staphylococcus spp. in Salad Vegetables: Biodiversity, Antimicrobial Resistance, and First Identification of Methicillin-Resistant Strains in the United Arab Emirates Food Supply

Contamination of leafy greens with Staphylococcus spp. can occur at various supply chain stages, from farm to table. This study comprehensively analyzes the species diversity, antimicrobial resistance, and virulence factors of Staphylococci in salad vegetables from markets in the United Arab Emirates (UAE). A total of 343 salad items were sampled from three major cities in the UAE from May 2022 to February 2023 and tested for the presence of Staphylococcus spp. using standard culture-based methods. Species-level identification was achieved using matrix-assisted laser desorption ionization-time of flight mass spectrometry. Antimicrobial susceptibility testing was conducted using the VITEK-2 system with AST-P592 cards. Additionally, whole genome sequencing (WGS) of ten selected isolates was performed to characterize antimicrobial resistance determinants and toxin-related virulence factors. Nine Staphylococcus species were identified in 37.6% (129/343) of the tested salad items, with coagulase-negative staphylococci (CoNS) dominating (87.6% [113/129]) and S. xylosus being the most prevalent (89.4% [101/113]). S. aureus was found in 4.6% (14/343) of the salad samples, averaging 1.7 log10 CFU/g. One isolate was confirmed as methicillin-resistant S. aureus, harboring the mecA gene. It belonged to multi-locus sequence type ST-672 and spa type t384 and was isolated from imported fresh dill. Among the characterized S. xylosus (n = 45), 13.3% tested positive in the cefoxitin screen test, and 6.6% were non-susceptible to oxacillin. WGS analysis revealed that the cytolysin gene (cylR2) was the only toxin-associated factor found in S. xylosus, while a methicillin-sensitive S. aureus isolate harbored the Panton-Valentine Leukocidin (LukSF/PVL) gene. This research is the first to document the presence of methicillin-resistant S. aureus in the UAE food chain. Furthermore, S. xylosus (a coagulase-negative staphylococcus not commonly screened in food) has demonstrated phenotypic resistance to clinically relevant antimicrobials. This underscores the need for vigilant monitoring of antimicrobial resistance in bacterial contaminants, whether pathogenic or commensal, at the human-food interface.

Methicillin-resistant Staphylococcus aureus prevalence in food-producing animals and food products in Saudi Arabia: A review

In Saudi Arabia, the occurrence of methicillin-resistant Staphylococcus aureus (MRSA) in food and livestock represents a major public health hazard. The emergence of livestock-associated MRSA has heightened the risk of human infection with comparable virulence traits. The lack of information about MRSA transmission in our region hinders accurate risk assessment, despite its detection in food animals and retail foods. Adopting a One Health approach is essential for effectively combating MRSA in Saudi Arabia. This method unites actions in the human, animal, and environmental spheres. To combat MRSA contamination, surveillance measures need strengthening; interdisciplinary collaboration among healthcare professionals, veterinarians, and environmental scientists is crucial, and targeted interventions must be implemented in local food chains and animal populations. Through a holistic strategy, public health and sustainable food production in the region are protected. This review aims to improve public health interventions by increasing understanding of MRSA prevalence and related risks in local food chains and animal populations.

Methicillin-Resistant Staphylococcus aureus (MRSA) in Dairy Products and Bulk-Tank Milk (BTM)

In order to contribute to an assessment of the role of food in the risks of transmission of methicillin-resistant Staphylococcus aureus (MRSA), a review was undertaken of research on this microorganism in milk and dairy products published from January 2001 to February 2024. A total of 186 publications were selected, 125 for dairy products and 61 for bulk-tank milk (BTM). MRSA was detected in 68.8% of the research into dairy products and 73.8% of investigations relating to BTM, although in most studies the prevalence was less than 5%. Of the set of S. aureus strains isolated, approximately 30% corresponded to MRSA. The foods most extensively contaminated with this microorganism were raw milk and some types of soft cheese. Determination of the mecA gene on its own is known not to suffice for the detection of all MRSA strains. The great diversity of techniques used to study MRSA in milk and dairy products made it difficult to draw comparisons between studies. It would thus be advisable to develop a standardized protocol for the study of this microorganism in foods.

Non-aureus staphylococci and mammaliicocci (NASM): their role in bovine mastitis and One Health

Non-aureus staphylococci (NAS) are gaining importance in mastitis and public health, and some NAS have been reclassified as mammaliicocci (NASM). Bovine milk production has a major influence on the world economy, being an essential source of income for small, medium and large producers, and bovine mastitis caused by NASM can cause an economic impact. Mastitis generates financial losses due to reduced revenue, increased veterinary costs and expenses associated with animal slaughter. However, it is also a public health issue involving animal health and welfare, human health and the ecosystem. Furthermore, it is an increasingly common infection caused by NASM, including antimicrobial-resistant strains. Despite all these adverse effects that NASM can cause, some studies also point to its protective role against mastitis. Therefore, this review article addresses the negative and positive aspects that NASM can cause in bovine mastitis, the virulence of the disease and resistance factors that make it difficult to treat and, through the One Health approach, presents a holistic view of how mastitis caused by NASM can affect both animal and human health at one and the same time.

Clonal Flux and Spread of Staphylococcus aureus Isolated from Meat and Its Genetic Relatedness to Staphylococcus aureus Isolated from Patients in Saudi Arabia

In this study, we investigated both meat-derived and methicillin-resistant Staphylococcus aureus (MRSA), exploring their genetic relatedness to patient-derived MRSA isolates in Saudi Arabia. We collected 250 meat samples and identified 53 S. aureus isolates, with 79% being methicillin-sensitive Staphylococcus aureus (MSSA) and 21% being MRSA. Moreover, we included 80 clinically confirmed patient-derived MRSA isolates. We identified the most common S. aureus clone in both patients and retail meat. In meat, ST6 and ST97 were the most common clones in 55% of the MRSA isolates, and ST1153 and ST672 were the most common in 21% and 17% of the MSSA isolates. In patients, ST5 and ST6 were the predominant clones in 46% of the S. aureus isolates. CC5/ST5-SCCmecVc-t311 and CC361/ST672-SCCmecV-t3841 were common MRSA clones in both meat and patients. CC97 and CC361 clones were the second most prevalent S. aureus clones in meat and were relatively common in patients. Furthermore, we sequenced and characterized novel S. aureus strains ST8109, ST8110, and ST8111. The genomic similarities between meat- and patient-derived S. aureus isolates suggest that retail meat might be a reservoir for S.aureus and MRSA transmission. Therefore, a structured One Health approach is recommended for S. aureus dissemination, genetic characterization, antibiotic resistance, and impact on human health.

The Socioeconomic Factors of Street Food Vending in Developing Countries and Its Implications for Public Health: A Systematic Review

The sale of ready-to-eat (RTE) street food represents an important source of income in many developing countries. However, these foods are frequently implicated in outbreaks of gastrointestinal diseases. Street food vendors face several constraints that hamper improvement in the microbiological quality of their products. The aim of this review was to update knowledge about the main causes of foodborne illnesses in developing countries, including the growing concern with the microbial transmission of antibiotic resistance. Following PRISMA guidelines, this systematic review was conducted on original articles published from January 2010 to July 2023. The search was carried out using Scopus, PubMed, Web of Science, Food Science and Technology Abstracts (FSTA), the International Information System for Agricultural Sciences and Technology (AGRIS), as well as isolated searches of relevant articles from Google Scholar. The initial search identified 915 articles, 50 of which were included in this systematic review. The results indicate that, in the majority of the 15 countries examined, women constitute the predominant segment of street food vendors, representing more than 55% of the total number of these vendors. In 11 countries, street food vendors under the age of 18 were identified. Most vendors had a low level of education and, consequently, were unaware of good hygiene practices when handling food. The combination of factors such as poor hygiene practices on the part of food handlers and the lack of facilities, namely, the absence of available potable water, were frequently listed as the main causes of food contamination. Enterobacteriaceae such as Escherichia coli (61.9%), Salmonella (30.1%), and Shigella spp. (9.5%), as well as Staphylococcus aureus (30.1%) and Listeria monocytogenes (14.3%), were the most common pathogens found in RTE street foods. In 22 studies from 13 developing countries, 59% (13/22) reported high multidrug resistance in Enterobacteriaceae (40% to 86.4% in E. coli, 16.7 to 70% in Salmonella, and 31 to 76.4% in S. aureus). To address the challenges faced by street vendors and improve their economic activities, it is necessary for government entities, consumers, and vendors to work together collaboratively.

Microbiological Quality and Safety of Fresh Quail Meat at the Retail Level

The objective of this study was to evaluate the microbiological quality and safety of 37 fresh quail meats. Mesophiles, Pseudomonas spp., Enterobacteriaceae, and staphylococci counts were 5.25 ± 1.14, 3.92 ± 1.17, 3.09 ± 1.02, and 2.80 ± 0.64 log CFU/g, respectively. Listeria monocytogenes was detected in seven samples (18.92%). Campylobacter jejuni was detected in one sample (2.70%). Clostridium perfringens was not detected in any sample. The dominant bacteria were Pseudomonas spp. (30.46%), Micrococcaceae (19.87%), lactic acid bacteria (14.57%), and Enterobacteriaceae (11.92%). Brochotrix thermosphacta and enterococci were isolated to a lesser extent, 7.28% and 1.99%, respectively. The dominant Enterobacteriaceae found were Escherichia coli (42.53%). ESBL-producing E. coli was detected in one sample (2.70%), showing resistance to 16 antibiotics. Sixteen different Staphylococcus spp. and three Mammaliicoccus spp. were identified, the most common being S. cohnii (19.86%) and M. sciuri (17.02%). S. aureus and S. epidermidis were also found in one and four samples, respectively. Methicillin-resistant M. sciuri and S. warneri were found in 13.51% and 10.81% of quail samples, respectively. These bacteria showed an average of 6.20 and 18.50 resistances per strain, respectively. The high resistance observed in ESBL-producing E. coli and methicillin-resistant S. warneri is of special concern. Measures should be adopted to reduce the contamination of quail meat.

Prevalence and Molecular Characterization of Methicillin-Resistant Staphylococci (MRS) and Mammaliicocci (MRM) in Dromedary Camels from Algeria: First Detection of SCCmec-mecC Hybrid in Methicillin-Resistant Mammaliicoccus lentus

Dromedary camels are an important source of food and income in many countries. However, it has been largely overlooked that they can also transmit antibiotic-resistant bacteria. The aim of this study was to identify the Staphylococcaceae bacteria composition of the nasal flora in dromedary camels and evaluate the presence of methicillin-resistant Mammaliicoccus (MRM) and methicillin-resistant Staphylococcus (MRS) in dromedary camels in Algeria. Nasal swabs were collected from 46 camels from seven farms located in two different regions of Algeria (M'sila and Ouargla). We used non-selective media to determine the nasal flora, and antibiotic-supplemented media to isolate MRS and MRM. The staphylococcal isolates were identified using an Autoflex Biotyper Mass Spectrometer (MALDI-TOF MS). The mecA and mecC genes were detected by PCR. Methicillin-resistant strains were further analysed by long-read whole genome sequencing (WGS). Thirteen known Staphylococcus and Mammaliicoccus species were identified in the nasal flora, of which half (49.2%) were coagulase-positive staphylococci. The results showed that four out of seven farms were positive for MRS and/or MRM, with a total of 16 isolates from 13 dromedary camels. The predominant species were M. lentus, S. epidermidis, and S. aureus. Three methicillin-resistant S. aureus (MRSA) were found to be ST6 and spa type t304. Among methicillin-resistant S. epidermidis (MRSE), ST61 was the predominant ST identified. Phylogenetic analysis showed clonal relatedness among M. lentus strains, while S. epidermidis strains were not closely related. Resistance genes were detected, including mecA, mecC, ermB, tet(K), and blaZ. An SCCmec type VIII element was found in a methicillin-resistant S. hominis (MRSH) belonging to the ST1 strain. An SCCmec-mecC hybrid element was detected in M. lentus, similar to what was previously detected in M. sciuri. This study highlights that dromedary camels may be a reservoir for MRS and MRM, and that they contain a specific set of SCCmec elements. This emphasizes the need for further research in this ecological niche from a One Health perspective.

Antimicrobial Activity of Sempervivum tectorum L. Extract on Pathogenic Bacteria Isolated from Otitis Externa of Dogs

The present study investigated the antimicrobial activity, total phenolic content, and proanthocyanidin concentration of ethanolic extracts from fresh leaves of Sempervivum tectorum L. The extracts were phytochemically analyzed and evaluated for antimicrobial activity. The broth microdilution method was used to assess antimicrobial activity against pathogenic bacteria isolated from ear swabs taken from dogs with otitis externa. Many compounds were present in the ethanolic aqueous extracts, which exhibited a broad spectrum of antimicrobial activity. They showed strong antibacterial activity against standard clinical Gram-positive strains such as S. aureus and Gram-negative strains such as P. aeruginosa. In our study, the obtained quantity of total phenolic compounds in the ethanol:water extract of leaves was 126.17 mg GAE/g. The proanthocyanidin concentration in the tested Sempervivum tectorum L. extracts was 15.39 mg PAC/g material. The high contents of total phenolics and proanthocyanidin indicated that these compounds contribute to antimicrobial activity. The antimicrobial activity of the tested S. tectorum L. extracts ranged from 1.47 to 63.75 µg/mL, starting with 1.47 µg/mL and 1.75 µg/mL against S. aureus ATCC 25923 and P. aeruginosa ATCC 27853 strains, respectively. Likewise, S. tectorum L. ethanol extract demonstrated a bacteriostatic effect against S. aureus clinical isolate with a median MIC of 23.25 µg/mL and MBC of 37.23 µg/mL; and bactericidal against S. aureus ATCC 25923 with the median MIC of 20.33 µg/mL and MBC of 37.29 µg/mL. In the Gram-negative P. aeruginosa clinical and standard strains, the expressed MIC and MBC values were 24.234 and 20.53 µg/mL for MIC, and 37.30 and 37.02 µg/mL for MBC, respectively.

Pet animals as reservoirs for spreading methicillin-resistant Staphylococcus aureus to human health

Methicillin-resistant Staphylococcus aureus (MRSA) is a strain of pathogenic bacteria that is a major problem in the world's health. Due to their frequent interaction with humans, pets are one of the main risk factors for the spread of MRSA. The possibility for zoonotic transmission exists since frequently kept dogs and cats are prone to contract MRSA and act as reservoirs for spreading MRSA. The mouth, nose, and perineum are the primary locations of MRSA colonization, according to the findings of MRSA identification tests conducted on pets. The types of MRSA clones identified in cats and dogs correlated with MRSA clones infecting humans living in the same geographic area. A significant risk factor for the colonization or transmission of MRSA is human-pet contact. An essential step in preventing the spread of MRSA from humans to animals and from animals to humans is to keep hands, clothing, and floor surfaces clean.

A Sequalae of Lineage Divergence in Staphylococcus aureus from Community-Acquired Patterns in Youth to Hospital-Associated Profiles in Seniors Implied Age-Specific Host-Selection from a Common Ancestor

The rapidly changing epidemiology of Staphylococcus aureus and evolution of strains with enhanced virulence is a significant issue in global healthcare. Hospital-associated methicillin-resistant S. aureus (HA-MRSA) lineages are being completely replaced by community-associated S. aureus (CA-MRSA) in many regions. Surveillance programs tracing the reservoirs and sources of infections are needed. Using molecular diagnostics, antibiograms, and patient demographics, we have examined the distributions of S. aureus in Ha'il hospitals. Out of 274 S. aureus isolates recovered from clinical specimens, 181 (66%, n = 181) were MRSA, some with HA-MRSA patterns across 26 antimicrobials with almost full resistances to all beta-lactams, while the majority were highly susceptible to all non-beta-lactams, indicating the CA-MRSA type. The rest of isolates (34%, n = 93) were methicillin-susceptible, penicillin-resistant MSSA lineages (90%). The MRSA in men was over 56% among total MRSA (n = 181) isolates and 37% of overall isolates (n = 102 of 274) compared to MSSA in total isolates (17.5%, n = 48), respectively. However, these were 28.4% (n = 78) and 12.4% (n = 34) for MRSA and MSSA infections in women, respectively. MRSA rates per age groups of 0-20, 21-50, and >50 years of age were 15% (n = 42), 17% (n = 48), and 32% (n = 89), respectively. However, MSSA in the same age groups were 13% (n = 35), 9% (n = 25), and 8% (n = 22). Interestingly, MRSA increased proportional to age, while MSSA concomitantly decreased, implying dominance of the latter ancestors early in life and then gradual replacement by MRSA. The dominance and seriousness of MRSA despite enormous efforts in place is potentially for the increased use of beta-lactams known to enhance virulence. The Intriguing prevalence of the CA-MRSA patterns in young otherwise healthy individuals replaced by MRSA later in seniors and the dominance of penicillin-resistant MSSA phenotypes imply three types of host- and age-specific evolutionary lineages. Thus, the decreasing MSSA trend by age with concomitant increase and sub-clonal differentiation into HA-MRSA in seniors and CA-MRSA in young and otherwise healthy patients strongly support the notion of subclinal emergences from a resident penicillin-resistant MSSA ancestor. Future vertical studies should focus on the surveillance of invasive CA-MRSA rates and phenotypes.

A PEGylated Nanostructured Lipid Carrier for Enhanced Oral Delivery of Antibiotics

Antimicrobial resistance is a major concern for public health throughout the world that severely restricts available treatments. In this context, methicillin-resistant Staphylococcus aureus (MRSA) is responsible for a high percentage of S. aureus infections and mortality. To overcome this challenge, nanoparticles are appropriate tools as drug carriers to improve the therapeutic efficacy and decrease the toxicity of drugs. In this study, a polyethylene glycol (PEG)ylated nanostructured lipid carrier (PEG-NLC) was synthesized to improve the oral delivery of trimethoprim/sulfamethoxazole (TMP/SMZ) for the treatment of MRSA skin infection in vitro and in vivo. The nanoformulation (PEG-TMP/SMZ-NLC) was synthesized with size and drug encapsulation efficiencies of 187 ± 9 nm and 93.3%, respectively, which could release the drugs in a controlled manner at intestinal pH. PEG-TMP/SMZ-NLC was found efficient in decreasing the drugs’ toxicity by 2.4-fold in vitro. In addition, the intestinal permeability of TMP/SMZ was enhanced by 54%, and the antibacterial effects of the drugs were enhanced by 8-fold in vitro. The results of the stability study demonstrated that PEG-TMP/SMZ-NLC was stable for three months. In addition, the results demonstrated that PEG-TMP/SMZ-NLC after oral administration could decrease the drugs’ side-effects such as renal and hepatic toxicity by ~5-fold in MRSA skin infection in Balb/c mice, while it could improve the antibacterial effects of TMP/SMZ by 3 orders of magnitude. Overall, the results of this study suggest that the application of PEGylated NLC nanoparticles is a promising approach to improving the oral delivery of TMP/SMZ for the treatment of MRSA skin infection.