Biofilm Dairy Foods Review: Effect of biofilm production on antimicrobial susceptibility of Staphylococcus aureus bovine mastitis strains from the most prevalent Canadian spa types.

Staphylococcus aureus intramammary infections often leads to clinical and subclinical mastitis in dairy cattle. Prediction of disease evolution and treatment efficacy based on the characteristics of disease-causing strains of S. aureus would significantly improve management of dairy herds. To study the impact of biofilm production and the influence of genetic lineage, we selected S. aureus isolates from the most prevalent Canadian spa types associated with bovine mastitis. Antimicrobial susceptibility in planktonic growth and for bacteria embedded in biofilm was compared. PCR was used to detect the bap gene responsible for atypical biofilm formation. All Canadian spa types from dairy cattle were susceptible to the 8 antimicrobial agents tested. Only strain sa3493 from spa type t267 showed a resistance to pirlimycin. However, bacteria producing larger amounts of biofilms better survived the bactericidal action of antimicrobial agents even when exposed to concentrations 64 folds higher than the minimal inhibitory concentration determined for planktonic cultures. Pirlimycin was more effective on bacteria producing low to moderate levels of biofilm compared with vancomycin or ceftiofur. Antimicrobial agents did not affect the viability of spa types t13401 and t605 that were high biofilm producers. While both these spa types produced high amounts of biofilm, only t605 possessed the bap gene. We also found a close relationship between DIM at sampling and the presence of spa type t605 isolates. These results suggest that detection of S. aureus spa type may help predict the effectiveness of antimicrobial therapy and that some spa types are more likely to be retrieved toward the end of the lactation.

Antibacterial activity of Bajakah Kalalawit phenolic against Staphylococcus aureus and possible use of phenolic nanoparticles.

Dayak tribes indigenous to the Indonesian island of Borneo has been using Bajakah Kalalawit (Uncaria gambir Roxb.) as traditional medicine for ages. This inspired us to develop phenolic from Bajakah Kalalawit extract as antibacterial agent. The extraction was done through decoction method and the determination of phenolic concentration was done using a visible spectrophotometer and Folin-Ciocalteu reagent (mixture of phosphotungstic and phosphomolybdic acids). We investigated the possibility of developing phenolic nanoparticle for future work. Kirby-Bauer method was used to assess antibacterial activity of phenolic against Staphylococcus aureus and the results were compared to Chloramphenicol in terms of its efficacy and duration of inhibition. This study contributes to the ongoing effort to address antibiotic resistance through the development of innovative antibacterial agents derived from natural sources. The results provide valuable insights into the potential of Bajakah Kalalawit phenolic extracts as a promising avenue for combating bacterial infections in the future.

Diffuse Alveolar Hemorrhage: A Rare Life-Threatening Cause of Massive Hemoptysis.

We present a case report of diffuse alveolar hemorrhage (DAH), which presented with massive hemoptysis and impending airway compromise. A previously healthy 33-year-old female presented to the emergency department with dyspnea, chest pain, and massive hemoptysis. Due to impending respiratory failure, the patient was placed on mechanical ventilation and a bronchoscopy revealed a diagnosis of DAH. Throughout the hospital course, the patient received antibiotics, steroids, fresh frozen plasma (FFP), cryoprecipitate, tranexamic acid (TXA), and multiple blood transfusions. The patient was subsequently placed on extracorporeal membrane oxygenation (ECMO), but despite these life-saving measures, the patient died less than 48 hours after her initial presentation. This case serves as a harrowing reminder of DAH's destructive capabilities and the importance of rapid, aggressive management.

"Unmasking a Looming Crisis: Escalating MIC of Last Resort Drugs against MRSA Isolates from a Tertiary Hospital in Central India."

PURPOSE: The Centers for Disease Control and Prevention has classified methicillin-resistant S aureus (MRSA) as a serious public health threat. The escalating minimum inhibitory concentration (MIC) of standard anti-methicillin-resistant S aureus (MRSA) drugs within the susceptible range, known as "MIC creep," jeopardizes their effectiveness against MRSA infections, posing additional challenges in managing MRSA infections. This cross-sectional study was conducted in a tertiary care hospital in Central India to assess the susceptibility trends of clinical MRSA isolates against commonly used anti-MRSA drugs and to observe MIC creep, if any, over three years (2020-2022). METHODS: The study included 158 non-repetitive clinical MRSA isolates. The MICs of vancomycin, teicoplanin, and linezolid were determined in MRSA strains using agar dilution, while the MIC of daptomycin was performed by broth microdilution. MIC creep was assessed by calculating MIC50, MIC90, Modal MIC, G-mean MIC, and susceptible and resistant percentages for the fiscal years 2020, 2021, and 2022. RESULTS: Of the 158 MRSA isolates, none were resistant to vancomycin, teicoplanin, and daptomycin, but two showed resistance to linezolid (LRSA). However, fifteen isolates showed intermediate resistance to vancomycin (VISA), and five showed intermediate resistance to teicoplanin (TISA). MIC of these anti-MRSA drugs increased in 2021 and 2022 compared to 2020. G-mean MIC for vancomycin, teicoplanin, and linezolid in MRSA strains increased significantly over the study period, while daptomycin MIC remained relatively stable, with a slight increase in 2021 and 2022. There was a high resistance rate for clindamycin, doxycycline, and chloramphenicol among VISA, TISA, and LRSA isolates compared to MRSA. CONCLUSIONS: During the three years of the study, "MIC creep" was observed in vancomycin, teicoplanin, and linezolid and, to some extent, for daptomycin in MRSA strains. The recovery of VISA, TISA, and linezolid-resistant MRSAs is worrisome, suggesting possible MRSA treatment failure and being a forerunner of resistant strains.

Exploring staphylococcus in urinary tract infections: A systematic review and meta-analysis on the epidemiology, antibiotic resistance and biofilm formation.

This study aimed to determine the epidemiology, biofilm formation and antibiotic resistance of staphylococci collected worldwide in the context of UTIs. This systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Forty studies from 23 countries were selected for quantitative review. Electronic databases (PubMed, Scopus, Google Scholar, and Web of Sciences) were searched for articles published between 2010 and 2024 on the epidemiology, biofilm formation, and antibiotic resistance of uropathogenic staphylococci. Strict inclusion and exclusion standards were applied during the review of the articles. Forty articles were included in this systematic review. The prevalence of uropathogenic staphylococci varies from country to country, with the pooled prevalence of S. aureus and coagulase-negative staphylococci (CoNS) being 8.71 % (95 %CI: 6.145-11.69) and 13.17 % (95 %CI: 8.08-19.27) respectively. Among CoNS isolates, S. epidermidis was the most common with 19.3 % (95 %CI: 5.88-38.05). The prevalence of methicillin-resistant S. aureus isolates increased significantly from 23 % in 2010-2015 to 47 % in 2021-2024 (p = 0.03). S. haemolyticus is the most antibiotic-resistant species in CoNS, with 45 % of isolates resistant to methicillin, 33 % to gentamicin, and 29 % to tetracycline. Eighty-eight S. aureus strains were biofilm producers, including 35 % moderate biofilm producers and 48 % strong biofilm producers. The combined frequencies of icaA, clfA and fnbpA were 100, 99, and 89 %, respectively. The development of antibiotic resistance and biofilm formation by staphylococci involved in UTIs explains the need for periodic regional surveillance of these infections, which poses a serious public health problem.

Unraveling the Challenges: A Compelling Case of Staph Meningitis and Graft Infection in a Bovine Brain Graft Recipient.

Meningitis due to Staphylococcus aureus is extremely rare, with an annual incidence of 1-3%. In this report, we present a rare case involving meningitis, an infected graft, and an infected fluid collection with two forms of S. aureus in a patient who received a bovine brain graft status post-decompression and suboccipital craniectomy with C1 laminectomy and duraplasty for Chiari malformation. The treatment approach included surgical debridement and graft retention, followed by an extended course of antibiotic treatment with oxacillin and rifampin. The patient successfully completed 12 weeks of total antibiotic therapy and was transitioned to suppressive therapy indefinitely with cefadroxil. This case highlights the importance of prompt identification and treatment of S. aureus meningitis due to the high mortality associated with this disease.

Mechanistic insights and in vivo efficacy of thiosemicarbazones against methicillin-resistant Staphylococcus aureus.

Staphylococcus aureus poses a significant threat in both community and hospital settings due to its infective and pathogenic nature combined with its ability to resist the action of chemotherapeutic agents. Methicillin-resistant S. aureus (MRSA) poses a critical challenge. Metal-chelating thiosemicarbazones (TSCs) have shown promise in combating MRSA and while previous studies hinted at the antimicrobial potential of TSCs, their mechanisms of action against MRSA are still under investigation. We screened a chemical library for anti-staphylococcal compounds and identified a potent molecule named R91 that contained the NNSN structural motif found within TSCs. We identified that R91 and several structural analogs exhibited antimicrobial activity against numerous S. aureus isolates as well as other Gram-positive bacteria. RNAseq analysis revealed that R91 induces copper and oxidative stress responses. Checkerboard assays demonstrated synergy of R91 with copper, nickel, and zinc. Mutation of the SrrAB two-component regulatory system sensitizes S. aureus to R91 killing, further linking the oxidative stress response to R91 resistance. Moreover, R91 was found to induce hydrogen peroxide production, which contributed to its antimicrobial activity. Remarkably, no mutants with elevated R91 resistance were identified, despite extensive attempts. We further demonstrate that R91 can be used to effectively treat an intracellular reservoir of S. aureus in cell culture and can reduce bacterial burdens in a murine skin infection model. Combined, these data position R91 as a potent TSC effective against MRSA and other Gram-positive bacteria, with implications for future therapeutic development.

Highly sensitive SERS nanoplatform based on aptamer and vancomycin for detection of S. aureus and its clinical application.

Staphylococcus aureus (S. aureus) is the most common pathogen in human purulent infections, which can cause local purulent infections, as well as pneumonia, pseudomembranous enteritis, pericarditis, and even systemic infections. The conventional methods including bacteria colony counting, polymerase chain reaction and enzyme-linked immunosorbent assay can't fully meet the requirement of highly sensitive detection of S. aureus due to their own disadvantages. Therefore, it's an urgent need to develop new platform to detect S. aureus in the early infection stage. In this study, a new surface-enhanced Raman scattering (SERS)-based nanoplatform based on dual-recognition of aptamer (Apt) and vancomycin (Van) was developed for the highly sensitive detection of S. aureus. The SERS nanoplatform consisted of two functional parts: aptamer-conjugated Fe3O4 magnetic nanoparticles (Fe3O4-Apt MNPs) for bacteria enrichment and vancomycin modified-Au nanoparticles (Van-Au NPs) as the SERS probes for S. aureus quantitative detection. Upon the target bacteria enrichment, the SERS signals of the supernatant after magnetic separation could be obtained and analyzed under different concentrations of S. aureus. The limit of detection of the proposed assay was found to be 3.27 CFU/mL. We believe that the proposed SERS-based nanoplatform has great potential as a powerful tool in the early detection of specific bacteria.

Structure of biofilm-forming functional amyloid PSMα1 from Staphylococcus aureus.

Biofilm-protected pathogenic Staphylococcus aureus causes chronic infections that are difficult to treat. An essential building block of these biofilms are functional amyloid fibrils that assemble from phenol-soluble modulins (PSMs). PSMα1 cross-seeds other PSMs into cross-ß amyloid folds and is therefore a key element in initiating biofilm formation. However, the paucity of high-resolution structures hinders efforts to prevent amyloid assembly and biofilm formation. Here, we present a 3.5 Å resolution density map of the major PSMα1 fibril form revealing a left-handed cross-ß fibril composed of two C2-symmetric U-shaped protofilaments whose subunits are unusually tilted out-of-plane. Monomeric α-helical PSMα1 is extremely cytotoxic to cells, despite the moderate toxicity of the cross-ß fibril. We suggest mechanistic insights into the PSM functional amyloid formation and conformation transformation on the path from monomer-to-fibril formation. Details of PSMα1 assembly and fibril polymorphism suggest how S. aureus utilizes functional amyloids to form biofilms and establish a framework for developing therapeutics against infection and antimicrobial resistance.

Phylogenetic analysis of Staphylococcus aureus enterotoxin A gene in Iraqi breed cows with bovine mastitis: Implications for disease management.

Background: Although milk is nutritionally valuable, it also serves as a significant medium for the transmission of pathogens and their toxins. Aim: This study aimed to investigate the role of enterotoxin gene A (SEA) in the development of bovine mastitis. We accomplished this by examining milk through polymerase chain reaction (PCR) testing, amino acid substitution analysis, and phylogenetic analysis. Methods: A total of fifty milk samples were collected from locally bred dairy cows in Al-Diwaniyah, located in southern Iraq. We employed the VITEK-2 platform to validate the diagnosis of Staphylococcus aureus and confirm the results of routine tests (culturing and biochemical tests). Subsequently, the genetic mutation and phylogeny analysis were achieved utilizing DNA sequencing to 16S rRNA and enterotoxin A genes. Results: 66% (33/50) of the milk samples found to be contain S. aureus by the VITEK-2 system. Furthermore, 25/33 of the samples were positive by the PCR test. While 60% (15 out of 25) tested positive for the SEA gene. After genomic analysis, we identified amino acid substitutions of serine, glutamine with arginine, tyrosine with cysteine, and aspartic acid with glycine at positions 9, 101, 119, 187, and 191. The phylogenetic investigation demonstrated a genetic relationship between our isolates (Iraqi isolates) and isolates from Indian and the United States. Conclusion: Our study indicated the widespread distribution of the enterotoxin gene A (SEA) of S. aureus among dairy cows. The molecular study revealed significant changes in key amino acids that could play an important role in the bacterium's pathogenesis. The phylogenetic similarities among S. aureus samples from various countries suggest that the bacteria has spread globally.

A rare biofilm dispersion strategy demonstrated by Staphylococcus aureus under oxacillin stress.

Staphylococcus aureus (S. aureus), a versatile Gram-positive bacterium, is implicated in a spectrum of infections, and its resilience is often attributed to biofilm formation. This study investigates the effect of sub-inhibitory doses of oxacillin on biofilm formation by methicillin-resistant S. aureus (MRSA). Specifically, it examines how these doses influence biofilms' development, maturation, and dispersal. The biofilm's zenith reached 48 h of incubation, followed by a noteworthy decline at 96 h and a distinctive clearance zone around biofilm-positive cells exposed to oxacillin. Scanning electron micrographs unveiled an intriguing active biofilm dispersal mechanism, a rarity in this species. Among 180 isolates, only three carrying the elusive icaD gene exhibited this phenomenon. icaD gene was absent in their counterparts. Notably, the icaD gene emerges as a distinctive marker, crucial in regulating biofilm dispersion and setting these isolates apart. The captivating interplay of oxacillin, biofilm dynamics, and genetic signatures disintegrate novel dimensions in understanding MRSA's adaptive strategies and underscores the importance of the icaD gene in engineering biofilm resilience.

Sinigrin reduces the virulence of Staphylococcus aureus by targeting coagulase.

Multi-resistant Staphylococcus aureus (S. aureus) infection is a significant global health concern owing to its high mortality and morbidity rates. Coagulase (Coa), a key enzyme that activates prothrombin to initiate host coagulation, has emerged as a promising target for anti-infective therapeutic approaches. This study identified sinigrin as a potent Coa inhibitor that significantly inhibited S. aureus-induced coagulation at concentration as low as 32 mg/L. Additionally, at a higher concentration of 128 mg/L, sinigrin disrupted the self-protection mechanism of S. aureus. Thermal shift and fluorescence-quenching assays confirmed the direct binding of sinigrin to the Coa protein. Molecular docking analysis predicted specific binding sites for sinigrin in the Coa molecule, and point mutation experiments highlighted the importance of Arg-187 and Asp-222 as critical binding sites for both Coa and sinigrin. In vivo studies demonstrated that the combination of sinigrin with oxacillin exhibited greater antibacterial efficacy than oxacillin alone in the treatment of S. aureus-induced pneumonia in mice. Furthermore, sinigrin was shown to reduce bacterial counts and inflammatory cytokine levels in the lung tissues of S. aureus-infected mice. In summary, sinigrin was shown to directly target Coa, resulting in the attenuation of S. aureus virulence, which suggests the potential of sinigrin as an adjuvant for future antimicrobial therapies.

Osteomyelitis-relevant antibiotics at clinical concentrations show limited effectivity against acute and chronic intracellular S. aureus infections in osteocytes.

Osteomyelitis caused by Staphylococcus aureus can involve the persistent infection of osteocytes. We sought to determine if current clinically utilized antibiotics were capable of clearing an intracellular osteocyte S. aureus infection. Rifampicin, vancomycin, levofloxacin, ofloxacin, amoxicillin, oxacillin, doxycycline, linezolid, gentamicin, and tigecycline were assessed for their minimum inhibitory concentration (MIC) and minimum bactericidal concentrations against 12 S. aureus strains, at pH 5.0 and 7.2 to mimic lysosomal and cytoplasmic environments, respectively. Those antibiotics whose bone estimated achievable concentration was commonly above their respective MIC for the strains tested were further assayed in a human osteocyte infection model under acute and chronic conditions. Osteocyte-like cells were treated at 1×, 4×, and 10× the MIC for 1 and 7 days following infection (acute model), or at 15 and 21 days of infection (chronic model). The intracellular effectivity of each antibiotic was measured in terms of CFU reduction, small colony variant formation, and bacterial mRNA expression change. Only rifampicin, levofloxacin, and linezolid reduced intracellular CFU numbers significantly in the acute model. Consistent with the transition to a non-culturable state, few if any CFU could be recovered from the chronic model. However, no treatment in either model reduced the quantity of bacterial mRNA or prevented non-culturable bacteria from returning to a culturable state. These findings indicate that S. aureus adapts phenotypically during intracellular infection of osteocytes, adopting a reversible quiescent state that is protected against antibiotics, even at 10× their MIC. Thus, new therapeutic approaches are necessary to cure S. aureus intracellular infections in osteomyelitis.

Conserved moonlighting protein pyruvate dehydrogenase induces robust protection against Staphylococcus aureus infection.

Developing an effective Staphylococcus aureus (S. aureus) vaccine has been a challenging endeavor, as demonstrated by numerous failed clinical trials over the years. In this study, we formulated a vaccine containing a highly conserved moonlighting protein, the pyruvate dehydrogenase complex E2 subunit (PDHC), and showed that it induced strong protective immunity against epidemiologically relevant staphylococcal strains in various murine disease models. While antibody responses contributed to bacterial control, they were not essential for protective immunity in the bloodstream infection model. Conversely, vaccine-induced systemic immunity relied on γδ T cells. It has been suggested that prior S. aureus exposure may contribute to the reduction of vaccine efficacy. However, PDHC-induced protective immunity still facilitated bacterial clearance in mice previously exposed to S. aureus. Collectively, our findings indicate that PDHC is a promising serotype-independent vaccine candidate effective against both methicillin-sensitive and methicillin-resistant S. aureus isolates.

Antibiogram profiling and detection of icaA and blaZ genes from Staphylococcus aureus and coagulase-negative Staphylococcus spp. of healthy bovine raw milk sample origin.

Objective: This study focused on the antibiogram profiling of Staphylococcus aureus and coagulase-negative Staphylococcus spp. (CoNS) and the detection of icaA and blaZ genes from bovine raw milk samples. Materials and Methods: Bovine milk samples were collected from dairy farms, and Staphylococcus spp. were isolated and identified via conventional and molecular screening. Disk diffusion test (DDT) was implemented to determine the resistance pattern. Biofilm and ß-lactamase-producing Staphylococcus spp. were identified via amplification of the icaA and blaZ genes. Methicillin-resistant Staphylococcus aureus and CoNS were identified by DDT and PCR of the mecA gene. Results: From 63 samples, 35 were confirmed as Staphylococcus spp., of which 16 (25.39%) S. aureus isolates were coagulase-positive, while 19 (30.16%) were negative. PCR confirmed that 50% (8/16) of S. aureus and 36.84% (7/19) of CoNS possessed the icaA gene. All S. aureus isolates were found resistant to penicillin-G (P) both phenotypically and genotypically. The isolates were also resistant to erythromycin (ERY) and oxytetracycline (TET). While CoNS showed high to reduced resistance against P, TET, ERY, and azithromycin, no S. aureus isolates were resistant to sulfamethoxazole, while 10.53% of CoNS isolates were. All S. aureus and CoNS isolates were susceptible to vancomycin and gentamicin. MR was exhibited by 37.5% of S. aureus and 42.10% of CoNS isolates. Moreover, S. aureus and CoNS had 56.25% and 52.63% multidrug-resistant (MDR) isolates, respectively. Conclusion: The present study revealed the presence of a biofilm-producing, MDR staphylococcal strain in milk that might endanger consumers. Routine surveillance and monitoring, along with antimicrobial resistance learning, can reduce risks.

Evaluation of the effectiveness of some essential oils against zoonotic methicillin-resistant Staphylococcus aureus isolated from dairy products and humans.

Objective: Staphylococcus aureus (S. aureus) is a zooanthroponotic, nosocomial, and community-associated pathogen that threatens livestock management and even public health. The goal of this investigation was to clarify the role of S. aureus in zoonotic illnesses. Besides that, a novel trial was conducted in the current Egyptian study using oil extracts such as cactus oil, tea oil, geranium oil, and thyme oil to demonstrate the susceptibility of methicillin-resistant S. aureus (MRSA) isolates to these organic oils in response to the alarming global concern regarding the decreased susceptibility of S. aureus to known antibiotics, which exacerbates control and treatment protocols. Materials and Methods: A total of 110 samples (45 raw cattle milk samples, 35 Karish cheese samples, and 30 human sputum samples) were collected. The bacterium was identified via traditional culturing methods, Gram staining, and the application of several biochemical tests. After that, various kinds of known commercial antibiotics were used to detect the antimicrobial susceptibility (AMS) of the obtained isolates. Furthermore, conventional polymerase chain reaction (PCR) testing was performed to identify S. aureus (nuc gene) and MRSA (mecA gene), with further application of multiplex PCR for screening of all the obtained isolates for vancomycin resistance via targeting vanA, vanB, and vanC genes. Finally, the agar gel diffusion method was performed to assess the antibacterial activity of four plant extracts (cactus oil, tea oil, geranium oil, and thyme oil) against the obtained MRSA. Results: The culturing method revealed S. aureus positivity in raw cattle milk (13.33%), in Karish cheese (28.57%), and in human samples (20%). The obtained isolates showed mainly resistance to amoxicillin-clavulanic and ampicillin antibiotics, while the dairy samples showed further resistance against ceptaxime and an intermediate reaction against erythromycin. On the molecular side, PCR positivity was present in human samples (10%), raw cow milk (13.33%), and Karish cheese (14.29%). Nine of the fourteen PCR isolates were methicillin-resistant S. aureus (MRSA) isolates. Comparing the four oil extracts against the acquired MRSA isolates, cactus oil extract proved to be the most effective. Conclusion: The study's results are highly promising as they support the notion that certain essential oils possess strong antimicrobial properties against zoonotic S. aureus, thereby reducing the excessive use of antibiotics in veterinary and medical settings.

Potential antivirulence and antibiofilm activities of sub-MIC of oxacillin against MDR S. aureus isolates: an in-vitro and in-vivo study.

BACKGROUND: Multi-drug resistant Staphylococcus aureus is one of the most common causes of nosocomial and community-acquired infections, with high morbidity and mortality. Treatment of such infections is particularly problematic; hence, it is complicated by antibiotic resistance, and there is currently no reliable vaccine. Furthermore, it is well known that S. aureus produces an exceptionally large number of virulence factors that worsen infection. Consequently, the urgent need for anti-virulent agents that inhibit biofilm formation and virulence factors has gained momentum. Therefore, we focused our attention on an already-approved antibiotic and explored whether changing the dosage would still result in the intended anti-virulence effect. METHODS: In the present study, we determined the antibiotic resistance patterns and the MICs of oxacillin against 70 MDR S. aureus isolates. We also investigated the effect of sub-MICs of oxacillin (at 1/4 and 1/8 MICs) on biofilm formation using the crystal violet assay, the phenol-sulphuric acid method, and confocal laser scanning microscopy (CLSM). We examined the effect of sub-MICs on virulence factors and bacterial morphology using quantitative reverse transcription polymerase chain reaction (qRT-PCR) and electron microscopy, respectively. Moreover, we studied the effect of sub-MICs of oxacillin (OX) in-vivo using a wound infection model. RESULTS: Oxacillin at 1/2 MIC showed a significant decrease in bacterial viability, while 1/4 and 1/8 MICs had negligible effects on treated bacterial isolates. Treatment of MDR isolates with 1/4 or 1/8 MICs of oxacillin significantly reduced biofilm formation (64% and 40%, respectively). The treated MDR S. aureus with sub-MICs of OX exhibited a dramatic reduction in several virulence factors, including protease, hemolysin, coagulase, and toxic shock syndrome toxin-1 (TSST-1) production. The sub-MICs of OX significantly decreased (P < 0.05) the gene expression of biofilm and virulence-associated genes such as agrA, icaA, coa, and tst. Furthermore, oxacillin at sub-MICs dramatically accelerated wound healing, according to the recorded scoring of histological parameters. CONCLUSION: The treatment of MDR S. aureus with sub-MICs of oxacillin can help in combating the bacterial resistance and may be considered a promising approach to attenuating the severity of S. aureus infections due to the unique anti-biofilm and anti-virulence activities.

Susceptibility of Staphylococcus aureus to Anti-Inflammatory Drugs with a Focus on the Combinatory Effect of Celecoxib with Oxacillin In Vitro.

Musculoskeletal infections (MIs) are among the most difficult-to-treat staphylococcal diseases due to antibiotic resistance. This has encouraged the development of innovative strategies, such as combination therapy, to combat MI. The aim of this study was to investigate the in vitro antistaphylococcal activity of anti-inflammatory drugs and the combined antimicrobial effect of celecoxib and oxacillin. The minimum inhibitory concentrations (MICs) of 17 anti-inflammatory drugs against standard strains and clinical isolates of S. aureus, including methicillin-resistant strains (MRSAs), were determined using the broth microdilution method. The fractional inhibitory concentration indices (FICIs) were evaluated using checkerboard assays. Celecoxib produced the most potent antistaphylococcal effect against all tested strains (MICs ranging from 32 to 64 mg/L), followed by that of diacerein against MRSA3 and MRSA ATCC 33592 (MIC 64 mg/L). Several synergistic effects were observed against the tested S. aureus strains, including MRSA (FICI ranging from 0.087 to 0.471). The strongest synergistic interaction (FICI 0.087) was against MRSA ATCC 33592 at a celecoxib concentration of 2 mg/L, with a 19-fold oxacillin MIC reduction (from 512 to 26.888 mg/L). This is the first report on the combined antistaphylococcal effect of celecoxib and oxacillin. These findings suggest celecoxib and its combination with oxacillin as perspective agents for research focused on the development of novel therapies for MI caused by S. aureus. This study further indicates that celecoxib could resensitize certain MRSA strains, in some cases, to be susceptible to ß-lactams (e.g., oxacillin) that were not previously tested. It is essential to mention that the in vitro concentrations of anti-inflammatory drugs are higher than those typically obtained in patients. Therefore, an alternative option for its administration could be the use of a drug delivery system for the controlled slow release from an implant at the infection site.

Benefits of Core-Shell Particles over Single-Metal Coatings: Mechanical and Chemical Exposure and Antimicrobial Efficacy.

One of the greatest challenges worldwide is containing the spread of problematic microorganisms. A promising approach is the use of antimicrobial coatings (AMCs). The antimicrobial potential of certain metals, including copper and zinc, has already been verified. In this study, polyethylene terephthalate and aluminum (PET-Al) foils were coated with copper, zinc, and a combination of these two metals, known as core-shell particles, respectively. The resistance of the three different types of coatings to mechanical and chemical exposure was evaluated in various ways. Further, the bacteria Staphylococcus aureus and the bacteriophage ϕ6 were used to assess the antimicrobial efficacy of the coatings. The best efficacy was achieved with the pure copper coating, which was not convincing in the abrasion tests. The result was a considerable loss of copper particles on the surfaces and reduced effectiveness against the microorganisms. The core-shell particles demonstrated better adhesion to the surfaces after abrasion tests and against most chemical agents. In addition, the antimicrobial efficiency remained more stable after the washability treatment. Thus, the core-shell particles had several benefits over the pure copper and zinc coatings. In addition, the best core-shell loading for durability and efficacy was determined in this study.

Estimating bacterial load in S. aureus and E. coli bacteremia using bacterial growth graph from the continuous monitoring blood culture system.

BACKGROUND: We examined whether the time to positivity (TTP) and growth and detection plot graph (GDPG) created by the automated blood culture system can be used to determine the bacterial load in bacteremic patients and its potential association correlation with disease severity. METHODS: Known bacterial inocula were injected into the blood culture bottles. The GDPGs for the specific inocula were downloaded and plotted. A cohort of 30 consecutive clinical cultures positive for S. aureus and E. coli was identified. Bacterial load was determined by comparing the GDPG with the "standard" curves. Variables associated with disease severity were compared across 3 bacterial load categories (< 100, 100-1000, > 1000 CFU/mL). RESULTS: S. aureus growth was sensitive to the blood volume obtained whereas E. coli growth was less so. A 12-hour delay in sample transfer to the microbiology laboratory resulted in a decrease in TTP by 2-3 h. Mean TTP was 15 and 10 h for S. aureus and E. coli, respectively, which correlates with > 1000 CFU/mL and 500-1000 CFU/ml. For S. aureus, patients with a bacterial load > 100 CFU/mL had a higher mortality rate, (OR for death = 9.7, 95% CI 1.6-59, p = 0.01). Bacterial load > 1000 CFU/mL had an odds ratio of 6.4 (95% CI1.2-35, p = 0.03) to predict an endovascular source. For E. coli bacteremia, we did not find any correlations with disease severity. CONCLUSION: GDPG retrieved from the automated blood culture system can be used to estimate bacterial load. S.aureus bacterial load, but not E.coli, was associated with clinical outcome.