Methicillin-susceptible Strains Research Articles

The efficacy of the food-grade antimicrobial xanthorrhizol against Staphylococcus aureus is associated with McsL channel expression.

The emergence and spread of multidrug-resistant Staphylococcus aureus strains demonstrates the urgent need for new antimicrobials. Xanthorrhizol, a plant-derived sesquiterpenoid compound, has a rapid killing effect on methicillin-susceptible strains and methicillin-resistant strains of S. aureus achieving the complete killing of staphylococcal cells within 2 min using 64 μg/mL xanthorrhizol. However, the mechanism of its action is not yet fully understood. The S. aureus cells treated with xanthorrhizol were studied using optical diffraction tomography. Activity of xanthorrhizol against the wild-type and mscL null mutant of S. aureus ATCC 29213 strain was evaluated in the time-kill assay. Molecular docking was conducted to predict the binding of xanthorrhizol to the SaMscL protein. Xanthorrhizol treatment of S. aureus cells revealed a decrease in cell volume, dry weight, and refractive index (RI), indicating efflux of the cell cytoplasm, which is consistent with the spontaneous activation of the mechanosensitive MscL channel. S. aureus ATCC 29213ΔmscL was significantly more resistant to xanthorrhizol than was the wild-type strain. Xanthorrhizol had an enhanced inhibitory effect on the growth and viability of exponentially growing S. aureus ATCC 29213ΔmscL cells overexpressing the SaMscL protein and led to a noticeable decrease in their viability in the stationary growth phase. The amino acid residues F5, V14, M23, A79, and V84 were predicted to be the residues of the binding pocket for xanthorrhizol. We also showed that xanthorrhizol increased the efflux of solutes such as K+ and glutamate from S. aureus ATCC 29213ΔmscL cells overexpressing SaMscL. Xanthorrhizol enhanced the antibacterial activity of the antibiotic dihydrostreptomycin, which targets the MscL protein. Our findings indicate that xanthorrhizol targets the SaMscL protein in S. aureus cells and may have important implications for the development of a safe antimicrobial agent.

Evaluating the antimicrobial and anti-biofilm activity of three synthetic antimicrobial Citropin analogs and their ability to fight against Staphylococcus aureus and Staphylococcus pseudintermedius.

We developed three new analogs of the antimicrobial peptide (AMP) Citropin 1.1: DAN-1-13, AJP-1-1, and HHX-2-28, and tested their potential antimicrobial and antibiofilm activities against Staphylococcus aureus and S. pseudintermedius. Potential cytotoxic or hemolytic effects were determined using cultured human keratinocytes and erythrocytes to determine their safety. To assess the antimicrobial activity of each compound, minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) were determined against methicillin-resistant and methicillin-susceptible strains of S. aureus and S. pseudintermedius. Activity against newly formed and mature biofilms was determined in two clinical isolates using spectrophotometry and scanning electron microscopy (SEM). All three compounds exhibited antimicrobial and bactericidal activity against all studied S. aureus and S. pseudintermedius strains, with MICs ranging from 4-32μg ml-1 and MBCs ranging from 8-128μg ml-1. Subinhibitory concentrations of all compounds also showed ant-biofilm activity in the two tested isolates. All compounds exhibited limited cytotoxic and hemolytic activity. Novel analogs of Citropin 1.1 exhibit antimicrobial and bactericidal activities against S. aureus and S. pseudintermedius isolates and inhibit the biofilm formation of these bacteria.

Increased production of aureolysin and staphopain A is a primary determinant of the reduced virulence of Staphylococcus aureus sarA mutants in osteomyelitis.

We previously demonstrated that mutation of sarA in Staphylococcus aureus limits biofilm formation, cytotoxicity for osteoblasts and osteoclasts, and virulence in osteomyelitis, and that all of these phenotypes can be attributed to the increased production of extracellular proteases. Here we extend these studies to assess the individual importance of these proteases alone and in combination with each other using the methicillin-resistant USA300 strain LAC, the methicillin-susceptible USA200 strain UAMS-1, and isogenic sarA mutants that were also unable to produce aureolysin (Aur), staphopain A (ScpA), staphylococcal serine protease A (subsp.), staphopain B (SspB), and the staphylococcal serine protease-like proteins A-F (SplA-F). Biofilm formation was restored in LAC and UAMS-1 sarA mutants by subsequent mutation of aur and scpA, while mutation of aur had the greatest impact on cytotoxicity to mammalian cells, particularly with conditioned medium (CM) from the more cytotoxic strain LAC. However, SDS-PAGE and western blot analysis of CM confirmed that mutation of sspAB was also required to mimic the phenotype of sarA mutants unable to produce any extracellular proteases. Nevertheless, in a murine model of post-traumatic osteomyelitis, mutation of aur and scpA had the greatest impact on restoring the virulence of LAC and UAMS-1 sarA mutants, with concurrent mutation of sspAB and the spl operon having relatively little effect. These results demonstrate that the increased production of Aur and ScpA in combination with each other is a primary determinant of the reduced virulence of S. aureus sarA mutants in diverse clinical isolates including both methicillin-resistant and methicillin-susceptible strains.IMPORTANCEPrevious work established that SarA plays a primary role in limiting the production of extracellular proteases to prevent them from limiting the abundance of S. aureus virulence factors. Eliminating the production of all 10 extracellular proteases in the methicillin-resistant strain LAC has also been shown to enhance virulence in a murine sepsis model, and this has been attributed to the specific proteases Aur and ScpA. The importance of this work lies in our demonstration that the increased production of these same proteases largely accounts for the decreased virulence of sarA mutants in a murine model of post-traumatic osteomyelitis not only in LAC but also in the methicillin-susceptible human osteomyelitis isolate UAMS-1. This confirms that sarA-mediated repression of Aur and ScpA production plays a critical role in the posttranslational regulation of S. aureus virulence factors in diverse clinical isolates and diverse forms of S. aureus infection.

Novel small-molecule compound YH7 inhibits the biofilm formation of Staphylococcus aureus in a sarX-dependent manner.

The emergence of antibiotic-resistant and biofilm-producing Staphylococcus aureus isolates presents major challenges for treating staphylococcal infections. Biofilm inhibition is an important anti-virulence strategy. In this study, a novel maleimide-diselenide hybrid compound (YH7) was synthesized and demonstrated remarkable antimicrobial activity against methicillin-resistant S. aureus (MRSA) and methicillin-susceptible S. aureus (MSSA) in both planktonic cultures and biofilms. The minimum inhibitory concentration (MIC) of YH7 for S. aureus isolates was 16 µg/mL. Quantification of biofilms demonstrated that the sub-MIC (4 µg/mL) of YH7 significantly inhibits biofilm formation in both MSSA and MRSA. Confocal laser scanning microscopy analysis further confirmed the biofilm inhibitory potential of YH7. YH7 also significantly suppressed bacterial adherence to A549 cells. Moreover, YH7 treatment significantly inhibited S. aureus colonization in nasal tissue of mice. Preliminary mechanistic studies revealed that YH7 exerted potent biofilm-suppressing effects by inhibiting polysaccharide intercellular adhesin (PIA) synthesis, rather than suppressing bacterial autolysis. Real-time quantitative PCR data indicated that YH7 downregulated biofilm formation-related genes (clfA, fnbA, icaA, and icaD) and the global regulatory gene sarX, which promotes PIA synthesis. The sarX-dependent antibiofilm potential of YH7 was validated by constructing S. aureus NCTC8325 sarX knockout and complementation strains. Importantly, YH7 demonstrated a low potential to induce drug resistance in S. aureus and exhibited non-toxic to rabbit erythrocytes, A549, and BEAS-2B cells at antibacterial concentrations. In vivo toxicity assays conducted on Galleria mellonella further confirmed that YH7 is biocompatible. Overall, YH7 demonstrated potent antibiofilm activity supports its potential as an antimicrobial agent against S. aureus biofilm-related infections. IMPORTANCE Biofilm-associated infections, characterized by antibiotic resistance and persistence, present a formidable challenge in healthcare. Traditional antibacterial agents prove inadequate against biofilms. In this study, the novel compound YH7 demonstrates potent antibiofilm properties by impeding the adhesion and the polysaccharide intercellular adhesin production of Staphylococcus aureus. Notably, its exceptional efficacy against both methicillin-resistant and methicillin-susceptible strains highlights its broad applicability. This study highlights the potential of YH7 as a novel therapeutic agent to address the pressing issue of biofilm-driven infections.

Chemical composition, antimicrobial and antiproliferative activity of the essential oil from Ambrosia artemisiifolia L

ABSTRACT The aim of our study was to characterize the composition and certain bioactivities of the essential oil of Ambrosia artemisiifolia. Eighty organic compounds were identified in the essential oils obtained by hydrodistillation and microwave-assisted isolation. Germacrene D was the main component in both oils. The essential oil obtained by hydrodistillation exerted antibacterial activity against two S. aureus strains, with MIC values of 0.015% for the methicillin-susceptible strain and 0.25% for the methicillin-resistant strain. In the biofilm formation assay, a dose-dependent inhibition was observed in case of the K. pneumoniae ATCC 600,703. In the ethidium bromide accumulation assay, a dose-dependent inhibition activity was observed against the bacterial efflux pump of the Gram-negative bacteria E. coli ATCC 25,922. The essential oil displayed strong in vitro cytotoxicity against the multidrug-resistant (MDR) Colo 320 cancer cell line with an IC50 value of 0.0103%. The essential oil showed strong inhibition on the proliferation of the doxorubicin-sensitive Colo 205 cells (IC50 values of 0.054%) and in the case of MDR Colo 320 colonic adenocarcinoma cells (IC50 values of 0.008%). This is the first report of the cytotoxic and antiproliferative activities of the essential oil from these species.

Efficacy of ceftobiprole in a murine model of bacteremia and disseminated infection.

Introduction. Ceftobiprole is an advanced-generation broad-spectrum parenteral cephalosporin with activity against MSSA and MRSA.Gap Statement. Ceftobiprole is not currently approved for use to treat S. aureus bacteremia and phase three clinical trials are taking place. Drug approval requires further pre-clinical evidence to support this new indication.Aim. The aim of this study was to evaluate the efficacy of ceftobiprole at the human equivalent efficacious exposure (considering a 500 mg q8h dosing regimen infused over 2 h) against MSSA and MRSA strains in a neutropenic murine model of bacteremia and disseminated infection.Methodology. Two bioluminescent-tagged strains (one MSSA and one MRSA strain) were selected based on their in vitro susceptibility and in vivo growth profiles. Bacterial c.f.u. counts in the blood, lung, kidney, and liver were determined 48 h post-infection or after death. The bioluminescent-tag allowed the visualization of the real-time effects of ceftobiprole therapy compared to the natural progression of the infection in untreated controls.Results. Treatment with ceftobiprole resulted in a significant reduction of the bacterial load with the bioluminescence reduced by 2-log units and bacterial c.f.u. counts reduced by 3- to 6-log units, depending on the organ and bacterial strain. Survival was 100 % in the ceftobiprole-treated group compared to only 0-20 % survival in the untreated control animals for both strains tested.Conclusion. These results suggest that treatment with ceftobiprole using a 500 mg q8h dosing regimen studied in several successful phase three trials, has potential as an antibiotic therapy to treat bacteremia and associated disseminated infections caused by either methicillin-susceptible or methicillin-resistant strains of S. aureus.

Molecular typing and characterization of Staphylococcus aureus isolates from burn wound infections in Fujian, China.

Staphylococcus aureus (S. aureus) is the most common causative agent of burn wound infection, that often leads to high morbidity and mortality. However, there is not enough knowledge about the molecular epidemiology and antimicrobial susceptibility of S. aureus isolates from burn wound infections in Fujian, China. Between 2016 and 2021, 90 S. aureus isolates were collected from burn wound infections in Fujian, China, including 59 methicillin-resistant (MRSA) strains and 31 methicillin-susceptible (MSSA) strains. These were investigated for molecular characteristics, virulence genes, biofilms, and antimicrobial susceptibility. All the isolates were genotyped by multilocus sequence typing (MLST), spa typing, agr typing, and SCCmec typing. Conventional PCR was performed for the detection of virulence genes. Biofilm formation capacity was assessed by tissue culture plate assay (TCP). The antimicrobial susceptibility of the isolates was evaluated using the dilution method. In total, 37 sequence types (ST) and 34 Staphylococcal protein A (spa) types (including a new type named spa-t20720) were identified based on multilocus sequence typing (MLST) and spa typing, respectively. CC8-ST239-t030-agrI-SCCmecIII (57.6%,34/59) and CC7-ST7-t091-agrI (16.1%, 5/31) represented the main clone of MRSA and MSSA isolates, respectively. Antibiotic susceptibility testing identified a significant difference in resistance rates between ST239 and non-ST239 isolates (p < 0.05). Twelve virulence genes were detected, of which the most common were icaA and icaD (both 100%), followed by icaB and icaC (both 96.7%), icaR (95.6%), lukED (81.1%), lukAB (62.2%), pvl (50%), hlgBC (26.7%), and eta (4.4%). Moreover, lukAB, hlgBC, agrI, and agrIII were significantly correlated with burn severity (p < 0.05). MRSA isolates were less likely, compared with MSSA isolates, to carry pvl, lukAB, and hlgBC (p < 0.05). A new spa type, t20720, was identified that contains pvl, lukED, lukAB, hlgBC, icaA, icaB, icaC, icaD, and icaR genes and has strong biofilm formation ability. CC8-ST239-t030-agrI-SCCmecIII and CC7-ST-7-t091-agrI were the prevalent molecular signatures of MRSA and MSSA isolates from burn wound infections in Fujian, China, respectively. The newly identified spa-t20720 isolate, which carries a wide range of virulence genes and has strong biofilm formation ability, requires special clinical attention.

Antimicrobial agents in small animal dermatology for treating staphylococcal infections.

Antibiotic recommendations for treating skin infections have been published many times in the past 30 years. Prior to 2000, the recommendations focused on the use of β-lactam antibiotics, such as cephalosporins, amoxicillin-clavulanate, or β-lactamase stable penicillins. These agents are still recommended, and used, for wild-type methicillin-susceptible strains of Staphylococcus spp. However, since the mid-2000s there has been an increase in methicillin-resistant Staphylococcus spp (MRSP). The increase among S pseudintermedius in animals coincided with the increase in methicillin-resistant S aureus that was observed in people near the same time. This increase led veterinarians to reevaluate their approach to treating skin infections, particularly in dogs. Prior antibiotic exposure and hospitalization are identified as risk factors for MRSP. Topical treatments are more often used to treat these infections. Culture and susceptibility testing is performed more often, especially in refractory cases, to identify MRSP. If resistant strains are identified, veterinarians may have to rely on antibiotics that were previously used uncommonly for skin infections, such as chloramphenicol, aminoglycosides, tetracyclines, and human-label antibiotics such as rifampin and linezolid. These drugs carry risks and uncertainties that must be considered before they are routinely prescribed. This article will discuss these concerns and provide veterinarians guidance on the treatment of these skin infections.

Case Studies.

British Journal of NursingVol. 32, No. Sup7 Case StudiesCase StudiesGema Munoz-Mozas, Colin Fairhurst, Simon ClareGema Munoz-MozasVascular Access Advanced Nurse Practitioner and Lead Vascular Access Nurse, Royal Marsden NHS Foundation TrustSearch for more papers by this author, Colin FairhurstVascular Access Advanced Clinical Practitioner, University Hospitals Plymouth NHS TrustSearch for more papers by this author, Simon ClareResearch and Practice Development Director, the Association for Safe Aseptic PracticeSearch for more papers by this authorGema Munoz-Mozas; Colin Fairhurst; Simon ClarePublished Online:10 Apr 2023https://doi.org/10.12968/bjon.2023.32.Sup7.S11AboutSectionsView articleView Full TextPDF/EPUB ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions ShareShare onFacebookTwitterLinked InEmail View article References Akhtar N, Lee L. Utilization and complications of central venous access devices in oncology patients. 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Virulent potential of methicillin-resistant and methicillin-susceptible Staphylococcus pseudintermedius in dogs

Staphylococcus pseudintermedius is a zoonotic pathogen responsible for several infectious diseases in pet animals, yet its pathogenic potential is not fully understood. Thus, this study aims to unravel the virulence profile of S. pseudintermedius from canine origin. Methicillin-resistant (MRSP) and methicillin-susceptible (MSSP) strains were isolated from different infection sites and their genotypic and phenotypic features were compared to determine the clinical implications of MRSP and MSSP strains. Bacterial identification was performed using MALDI-TOF and 16S-rDNA sequencing. In addition, we used multilocus sequence typing (MLST) for strains’ sequence type (ST) determination and phylogenetic relationship. The strains were screened for toxin genes, including cytotoxins (lukS, lukF), exfoliative toxin (siet), enterotoxins (sea, seb, sec, secCanine, sel, sem, and seq) and toxic shock syndrome toxin (tst-1). In vitro phenotypic analyses assessing antimicrobial susceptibility profile, biofilm formation ability, and expression of extracellular matrix components were performed. The investigated S. pseudintermedius strains belong to 17 unique ST, most of which were classified as ST71. MSSP and MRSP strains shared siet, lukS, and lukF virulence markers. Our findings showed that some MSSP strains also harbored sel, seq, and sem enterotoxin genes, suggesting a more diverse virulence profile. All MRSP strains and 77% of MSSP strains were classified as multidrug resistant (MDR). Moreover, all investigated S. pseudintermedius strains showed strong biofilm formation ability. In summary, our findings highlight the wide spread of highly virulent and drug-resistant zoonotic S. pseudintermedius strains, being a potential concern for One Health issues.

Differentiating methicillin resistant and susceptible Staphylococcus aureus from ocular infections using photoacoustic labeling.

Antibiotic resistance in bacterial species constitutes a growing problem in the clinical management of infections. Not only does it limit therapeutic options, but application of ineffective antibiotics allows resistant species to progress prior to prescribing more effective treatment to patients. Methicillin resistance in Staphylococcus aureus is a major problem in clinical infections as it is the most common hospital acquired infection. We developed a photoacoustic flow cytometer using engineered bacteriophage as probes for rapid determination of methicillin resistance in Staphylococcus aureus with thirteen clinical samples obtained from keratitis patients. This method irradiates cells under flow with 532 nm laser light and selectively generates acoustic waves in labeled bacterial cells, thus enabling detection and enumeration of them. Staphylococcus aureus isolates were classified from culture isolation as either methicillin resistant or susceptible using cefoxitin disk diffusion testing. The photoacoustic method enumerates bacterial cells before and after treatment with antibiotics. Decreasing counts of bacteria after treatment indicate susceptible strains. We quantified the bacterial cells in the treated and untreated samples. Using k-means clustering on the data, we achieved 100% concordance with the classification of Staphylococcus aureus resistance using culture. Photoacoustics can be used to differentiate methicillin resistant and susceptible strains of bacteria from ocular infections. This method may be generalized to other bacterial species using appropriate bacteriophages and testing for resistance using other antibiotics.

Dalbavancin (Xydalba)

&#x0D; CADTH reimbursement reviews are comprehensive assessments of the clinical effectiveness and cost-effectiveness, as well as patient and clinician perspectives, of a drug or drug class.&#x0D; The assessments inform non-binding recommendations that help guide the reimbursement decisions of Canada's federal, provincial, and territorial governments, with the exception of Quebec.&#x0D; This review assesses Dalbavancin (Xydalba) for injection, 500 mg (as dalbavancin hydrochloride) per vial, lyophilized powder for solution, IV infusion.&#x0D; Indication: Treatment of adults with acute bacterial skin and skin structure infections caused by susceptible isolates of the following gram-positive micro-organisms: Staphylococcus aureus (including methicillin-susceptible and methicillin-resistant strains), Streptococcus pyogenes, Streptococcus agalactiae, Streptococcus dysgalactiae, Streptococcus anginosus group (including Streptococcus anginosus, Streptococcus intermedius, Streptococcus constellatus), and Enterococcus faecalis (vancomycin-susceptible strains).&#x0D;

Molecular mechanisms of biofilm formation in Staphylococci bacteria: How antibiotic resistant bacteria is evolving to become more resilient to mechanical force loads.

Among the arsenal of virulence factors used by Staphylococcus aureus bacteria, adhesins play critical roles participating actively on the formation of biofilms. Combining single molecule force spectroscopy in vitro and in silico, we have discovered the extreme mechanostability of the interaction between pathogenic adhesins and proteins of the human extracellular matrix. Here we describe how Staphylococci adhesins use a catch-bond mechanism to hold tight to their human target peptides under high-force loads, while allowing for thermal dissociation in a low-force regime. Furthermore, we employed bioinformatic tools to retrieve and align nearly 200 proteins of the bacterial adhesin superfamily. Using AI-based protein structure prediction, we modelled, together with their human target, adhesins from methicillin susceptible strains of S. aureus (MSSA) and methicillin resistant strains of S. aureus (MRSA). Using GPU-accelerated NAMD 3, thousands of steered molecular dynamics (SMD) simulations were performed using a wide-sampling paradigm. Our protocol reveled that mechanostability is preserved among all strains with a pattern of higher forces for the MRSA strains. In summary, our work shows that the complex formed by Staphylococci adhesins with proteins of the human extracellular matrix is, by far, the most mechanically stable protein complex know to date, surpassing the mechanostability of the widely employed streptavidin:biotin complex by an order of magnitude. To keep such mechanostable complex, a catch-bond mechanism, where bonds live longer under mechanical load, is used by these adhesins. Additionally, we have recently discovered that the mechanostability of the complex is increasing with the evolution of these bacteria to become resistant to methicillin. With increasing prevalence of multidrug resistant bacterial infections, this new finding could be exploited for the development of antiadhesion strategies as an alternative to antibiotics.

Serrapeptase impairs biofilm, wall, and phospho-homeostasis of resistant and susceptible Staphylococcus aureus

Staphylococcus aureus biofilms are implicated in hospital infections due to elevated antibiotic and host immune system resistance. Molecular components of cell wall including amyloid proteins, peptidoglycans (PGs), and lipoteichoic acid (LTA) are crucial for biofilm formation and tolerance of methicillin-resistant S. aureus (MRSA). Significance of alkaline phosphatases (ALPs) for biofilm formation has been recorded. Serrapeptase (SPT), a protease of Serratia marcescens, possesses antimicrobial properties similar or superior to those of many antibiotics. In the present study, SPT anti-biofilm activity was demonstrated against S. aureus (ATCC 25923, methicillin-susceptible strain, methicillin-susceptible S. aureus (MSSA)) and MRSA (ST80), with IC50 values of 0.67 μg/mL and 7.70 μg/mL, respectively. SPT affected bacterial viability, causing a maximum inhibition of − 46% and − 27%, respectively. Decreased PGs content at [SPT] ≥ 0.5 μg/mL and ≥ 8 μg/mL was verified for MSSA and MRSA, respectively. In MSSA, LTA levels decreased significantly (up to − 40%) at lower SPT doses but increased at the highest dose of 2 μg/mL, a counter to spectacularly increased cellular and secreted LTA levels in MRSA. SPT also reduced amyloids of both strains. Additionally, intracellular ALP activity decreased in both MSSA and MRSA (up to − 85% and − 89%, respectively), while extracellular activity increased up to + 482% in MSSA and + 267% in MRSA. Altered levels of DING proteins, which are involved in phosphate metabolism, in SPT-treated bacteria, were also demonstrated here, implying impaired phosphorus homeostasis. The differential alterations in the studied molecular aspects underline the differences between MSSA and MRSA and offer new insights in the treatment of resistant bacterial biofilms.Key points• SPT inhibits biofilm formation in methicillin-resistant and methicillin-susceptible S. aureus.• SPT treatment decreases bacterial viability, ALP activity, and cell wall composition.• SPT-treated bacteria present altered levels of phosphate-related DING proteins.Graphical

Comparison of genotyping methods and toxin gene profiles of Staphylococcus aureus isolates from clinical specimens.

Staphylococcus aureus is a frequent cause of infections worldwide. Methicillin-resistant S. aureus (MRSA) is one of the main causes of Gram-positive infections, and methicillin-susceptible strains (MSSA) primarily colonize and infect community hosts. Multiple virulence factors are involved, with toxins playing a significant role in several diseases. In this study, we assess the prevalence of toxin genes in 89 S. aureus clinical isolates (31 MRSA and 58 MSSA). We evaluated the discriminatory power of the association of internal transcribed spacer-PCR (ITS-PCR) and 3'- end coa gene ( coa-PCR) when compared with other more commonly used and costly techniques. The isolates showed a high level of genetic diversity, and toxins were found in all the isolates. While most toxin classes displayed no statistically significant correlations and were equally distributed in isolates regardless of their resistance status, classic enterotoxins ( sea-see) showed a positive correlation with MSSA isolates. The combination of coa-PCR with ITS-PCR showed a discriminatory index of 0.84, discriminating 22 genotypes that agree with previously determined data by PFGE and MLST. This association between the two PCR-based methods suggests that they can be useful for an initial molecular epidemiological investigation of S. aureus in hospitals, providing significant information while requiring fewer resources.

Pathogenic potential and antimicrobial resistance of Staphylococcus pseudintermedius isolated from human and animals

Crossing of interspecies barriers by microorganisms is observed. In recent years, Staphylococcus pseudintermedius—a species formerly thought to be animal—has also been isolated from human clinical materials. Many virulence factors are responsible for the colonization, which is the first step an infection, of the new host organism. We analyzed the factors influencing this colonization as well as susceptibility to antibiotics in fourteen S. pseudintermedius strains isolated from clinical cases from humans and animals. The occurrence of genes responsible for binding elastin, fibronectin, and fibrinogen and some phenotypic features, although different between strains, is comparable in both groups. However, the animal isolates had more genes coding for virulence factors. All isolates tested had the exfoliating toxin gene and the leukotoxin determining genes, but only the human strains had enterotoxin genes. The assessment of antibiotic resistance of strains of both groups indicates their broad resistance to antibiotics commonly used in veterinary medicine. Antibiotic resistance was more common among animal isolates. The multilocus sequence typing analysis of the studied strains was performed. The results indicated a large diversity of the S. pseudintermedius population in both studied groups of strains. Equipped with important virulence factors, they showed the ability to infect animals and humans. The clonal differentiation of the methicillin-susceptible strains and the multidrug resistance of the strains of both studied groups should be emphasized. The considerable genetic diversity of strains from a limited geographical area indicates the processes of change taking place within this species. Thus, careful observation of the ongoing process of variation is necessary, as they may lead to the selection of S. pseudintermedius, which will pose a significant threat to humans.

Genome Sequencing of Methicillin-Resistant and Methicillin-Susceptible Mammaliicoccus sciuri from Diseased Animals.

ABSTRACTMammaliicoccus sciuri (previously Staphylococcus sciuri) is a frequent colonizer of mammals. We report the draft genomes of a methicillin-resistant strain (2254A) isolated from an armadillo and a methicillin-susceptible strain (6942A) from a cow. Genomes were sequenced using long-read Nanopore sequencing.

A Niclosamide-releasing hot-melt extruded catheter prevents Staphylococcus aureus experimental biomaterial-associated infection

Biomaterial-associated infections are a major healthcare challenge as they are responsible for high disease burden in critically ill patients. In this study, we have developed drug-eluting antibacterial catheters to prevent catheter-related infections. Niclosamide (NIC), originally an antiparasitic drug, was incorporated into the polymeric matrix of thermoplastic polyurethane (TPU) via solvent casting, and catheters were fabricated using hot-melt extrusion technology. The mechanical and physicochemical properties of TPU polymers loaded with NIC were studied. NIC was released in a sustained manner from the catheters and exhibited in vitro antibacterial activity against Staphylococcus aureus and Staphylococcus epidermidis. Moreover, the antibacterial efficacy of NIC-loaded catheters was validated in an in vivo biomaterial-associated infection model using a methicillin-susceptible and methicillin-resistant strain of S. aureus. The released NIC from the produced catheters reduced bacterial colonization of the catheter as well as of the surrounding tissue. In summary, the NIC-releasing hot-melt extruded catheters prevented implant colonization and reduced the bacterial colonization of peri-catheter tissue by methicillin sensitive as well as resistant S. aureus in a biomaterial-associated infection mouse model and has good prospects for preclinical development.

The FnBPA from methicillin-resistant Staphylococcus aureus promoted development of oral squamous cell carcinoma

ABSTRACT Background Oral squamous cell carcinoma (OSCC) is the most common tumor in the oral cavity. Methicillin-resistant Staphylococcus aureus (MRSA) were highly detected in OSCC patients; however, the interactions and mechanisms between drug-resistant bacteria (MRSA) and OSCC are not clear. Aim The aim of this study was to investigate the promotion of MRSA on the development of OSCC. Methods MRSA and MSSA (methicillin-susceptible) strains were employed to investigate the effect on the proliferation of OSCC in vitro and vivo. Results All of the MRSA strains significantly increased the proliferation of OSCC cells and MRSA arrested the cell cycles of OSCC cells in the S phase. MRSA activated the expression of TLR-4, NF-κB and c-fos in OSCC cells. MRSA also promoted the development of squamous cell carcinoma in vivo. The virulence factor fnbpA gene was significantly upregulated in all MRSA strains. By neutralizing FnBPA, the promotions of MRSA on OSCC cell proliferation and development of squamous cell carcinoma were significantly decreased. Meanwhile, the activation of c-fos and NF-κB by MRSA was also significantly decreased by FnBPA antibody. Conclusion MRSA promoted development of OSCC, and the FnBPA protein was the critical virulence factor. Targeting virulence factors is a new method to block the interaction between a drug-resistant pathogen and development of tumors.

Antimicrobial Activity of the Iron-Chelator, DIBI, against Multidrug-Resistant Canine Methicillin-Susceptible Staphylococcus pseudintermedius: A Preliminary Study of Four Clinical Strains.

Staphylococcus pseudintermedius is an important opportunistic pathogen causing various infections in dogs. Furthermore, it is an emerging zoonotic agent and both multidrug-resistant methicillin-resistant S. pseudintermedius (MRSP) as well as methicillin-susceptible (MSSP) strains represent an important therapeutic challenge to veterinary medicine and pose a potential threat to human health. We tested representative S. pseudintermedius clinical strains from dogs suffering from otitis externa for their susceptibilities to a panel of 17 antimicrobials compared to DIBI. DIBI, unlike antibiotics, is a novel water-soluble hydroxypyridinone-containing iron-chelating agent that deprives microbes of growth-essential iron and has been previously shown to inhibit methicillin-resistant Staphylococcus aureus (MRSA). We also characterised the strains according to whether they harbour key antibiotic resistance genes. The strains each displayed multiple antimicrobial resistance patterns; all were negative for the mecA gene and possessed the tetK and tetM genes, but they varied as to their possession of the ermB gene. However, all the isolates had similar susceptibility to DIBI with low MICs (2 µg/mL or 0.2 µM). Because the four MSSPs were equally susceptible to DIBI, subject to confirmation with additional strains, this could provide a potential non-antibiotic, anti-infective alternative approach for the treatment of antimicrobial-resistant canine S. pseudintermedius otitis.