Isolated Acromioclavicular Joint Septic Arthritis: A Case Report and Review of Literature.

A 60-year-old diabetic patient presented with acute pain and swelling localized to the left acromioclavicular joint. Laboratory and radiological investigations revealed the presence of pus in the left acromioclavicular joint along with bony erosion of the lateral end of the left clavicle. She was treated with open arthrotomy, debridement, and appropriate antibiotics for the causative methicillin-resistant Staphylococcus aureus (MRSA) infection. Prompt diagnosis and timely intervention can reduce the morbidity and mortality due to septic arthritis. We conducted a review of the literature on patients treated for isolated septic arthritis of the acromioclavicular joint.

An abysmal conundrum associated with a misplaced dialysis catheter.

A 25-year-old female patient with chronic glomerulonephritis, initiated on haemodialysis presented with high-grade fever, a dysfunctional catheter, low oxygen saturation and unstable blood pressure. Upon evaluation, the patient was febrile with elevated white blood cell counts. She was intubated, started on inotropes and transferred to the intensive care unit. Chest radiography showed that the tunnelled internal jugular dialysis catheter had migrated to the inferior vena cava. Echocardiography and transoesophageal echocardiography showed severe heart dysfunction with a large thrombus attached to the catheter, indicating catheter-related atrial thrombus (CRAT). CT pulmonary angiography revealed blockage of the segmental pulmonary arteries, suggesting pulmonary embolism. Blood and tracheal cultures revealed Methicillin-resistant Staphylococcus aureus (MRSA). The patient was administered appropriate antibiotics and anticoagulants and underwent surgical removal of the thrombus and the catheter. This case demonstrates the risks associated with improper placement of dialysis catheters and highlights the brief management of CRAT.

Novel pleuromutilin derivatives conjugated with phenyl-sulfide and boron-containing moieties as potent antibacterial agents against antibiotic-resistant bacteria.

In response to the escalating threat of microbial resistance, a series of novel pleuromutilin derivatives, conjugated with phenyl-sulfide and boron-containing moieties, were designed and synthesized. Most derivatives, especially 14b and 16b, demonstrated significant efficacy against Gram-positive bacteria, including multidrug-resistant strains, as well as pleuromutilin-resistant strains. Compound 16b showed high stability in the liver microsomes of rats and humans, along with acceptable tolerance in vitro and in vivo. Additionally, compound 16b exhibited promising efficacy in MRSA-infected mouse models. Our data highlight the potential of conjugated pleuromutilin derivatives as valuable agents against drug-resistant bacteria.

A Rare Occurrence of Methicillin-Resistant Staphylococcus aureus (MRSA) Pneumonia Complicated by Nasal Vestibulitis and Orbital Cellulitis: A Case Report.

We report the case of left lower lobe community-acquired methicillin-resistant Staphylococcus aureus (MRSA) pneumonia in an immunocompetent male in his 20s. His illness was complicated by the dramatic appearance of right nasal vestibulitis and right preseptal orbital cellulitis post-admission. The patient responded well to vancomycin and made a complete recovery. Community-acquired MRSA pneumonia in immunocompetent adults is a rare entity in India, and the combination with vestibulitis has not yet been reported. This hitherto unreported presentation sheds further light on the evolving pattern of MRSA infections in the community.

Comparison of the Effect of Different Treatment Doses of Intrastromal Vancomycin in a Rabbit Model of Methicillin-Resistant Staphylococcus Aureus (MRSA) Keratitis.

PURPOSE: To compare the effect of different doses of vancomycin on a rabbit model of MRSA keratitis. METHODS: Twenty-four eyes of 24 New-Zealand White rabbits were included in the study. MRSA keratitis was applied to 24 left eyes of 24 New Zealand rabbits. Twenty-four hours after MRSA inoculation; 0.5 mg/0.1 mL, 1 mg/0.1 mL, and 2 mg/0.1 mL and balanced salt solution were administered to 6 rabbits in 4 groups, respectively. RESULTS: The effect of different doses of vancomycin on reducing bacterial load was found to be statistically significant when each was compared to the control group (p = 0.006). When comparing the dosages with each other, no superiority was shown (p = 0.297, p = 0.749, p = 0.262 respectively). There was a significant increase in the posttreatment total clinical score in the control and 2 mg/0.1 mL groups compared to the pretreatment score (p = 0.001, p = 0.001 respectively). CONCLUSION: It is emphasized that necessary treatment can be achieved by administering less antibiotic (0.5 mg/0.1 mL) to the corneal intrastromal area.

The Impact of a Methicillin-Resistant Staphylococcus Aureus Nasal Polymerase Chain Reaction Protocol on Vancomycin Length of Therapy Among Patients With Skin and Soft Tissue Infections.

Objective: We evaluated the impact of a methicillin-resistant Staphylococcus aureus (MRSA) nasal polymerase chain reaction (PCR) protocol on the vancomycin length of therapy (LOT) for skin and soft tissue infections (SSTIs). Design: Retrospective quasi-experimental pre- and post- MRSA nasal PCR protocol implementation study. Setting: Tertiary-care academic medical center in Jacksonville, Florida. Patients: Eligible patients received empiric vancomycin for SSTIs from January 1st to September 30th 2020 (pre-implementation group) and from January 1st to September 30th 2022 (post-implementation group). Intervention: The electronic health system software was modified to provide a best-practice advisory (BPA) prompt to the pharmacist upon order verification of vancomycin for patients with SSTIs. Methods: We reviewed patient records to determine the time from vancomycin prescription to de-escalation. The secondary outcomes were incidence of acute kidney injury (AKI), number of vancomycin levels collected, and hospital length of stay (LOS). Results: The study included 131 patients (pre-implementation, n = 86 and post-implementation, n = 45). There was no significant difference in vancomycin length of therapy (LOT) between implementation groups: mean LOT in days and standard deviation (SD) were 2.7 (1.9) and 2.6 (1.3), respectively, p-value 0.493. Of significance, in the post-implementation group, vancomycin LOT between patients with a negative and positive MRSA PCR were 2.3 (1.1) and 3.9 (1.6), p-value 0.006. There was no difference in secondary outcomes. Conclusion: The utilization of the MRSA nasal PCR to guide vancomycin de-escalation did not significantly change the vancomycin LOT, however in the post-implementation group there was a significant difference in vancomycin LOT between negative and positive MRSA PCRs.

A ß-Lactamase Responsive Peptide Inhibits MRSA Infection through Self-Assembled Nanonet.

Gram-positive S. aureus is one of the leading pathogens for death associated with antimicrobial resistance. The ß-lactamase (Bla) secreted by methicillin-resistant S. aureus (MRSA) hydrolyzes nearly all ß-lactam antibiotics, leaving only a few antibiotics available for the clinical treatment of MRSA infections. Thereby, a Bla-responsive peptide (BLAP) is designed here with the capacity of inhibiting MRSA infection through mimicking the host defense mechanism of human defensin-6. The BLAP comprising a self-assembling peptide sequence can respond specifically to the secreted Bla and assemble in situ surrounding MRSA. The assembled nanofibrous network is able to trap MRSA, preventing its invasion into the host cells effectively. As a consequence, the intramuscular injection of BLAP significantly restricted bacterial infection and abscess formation in mice. The biomimetic BLAP holds great potential for the efficient treatment of drug-resistant gram-positive bacterial infections.

Rate of nosocomial MRSA transmission evaluated via contact screening.

BACKGROUND: The prevention of methicillin-resistant S. aureus (MRSA) transmission in the healthcare setting is a priority in Infection Control practices. A cornerstone of this policy is contact tracing of nosocomial contacts after an unexpected MRSA finding. The objective of this retrospective study was to quantify the rates of MRSA transmission in different clinical settings. METHODS: This multi-centre study included MRSA contact screening results from two regional hospitals and one academic hospital. MRSA contact tracing investigations from 2000 until 2019 were reviewed and post-contact screening results were included of index patients with an MRSA-positive culture and their unprotected contacts. Available typing results were used to rule out incidental findings. RESULTS: Of 27,377 contacts screened after MRSA exposure, 21,488 were Health Care Workers (HCW) and 4816 patients. Post-contact screening was initiated for a total of 774 index cases, the average number of screened contacts per index case was 35.7 (range 1 to 640). MRSA transmission was observed in 0.15% (41) of the contacts, 19 (0.09%) HCW and 22 (0.46%) patients. The number needed to screen to detect one MRSA transmission was 667. The highest risk of MRSA transmission occurred during patient-to-patient contacts, with transmission rates varying from 0.32 to 1.32% among the participating hospitals. No transmissions were detected in HCW (n=2834) in the outpatient setting, and the rate of transmissions among HCW contacts on the wards was 0.13% (19 of 15,874). Among 344 contacts of patients with contact precautions, no transmissions were detected. CONCLUSIONS: Reconsidering current MRSA contact tracing practices may lead to a more targeted approach with a lower number needed to screen.

Particulate 3D Hydrogels of Silk Fibroin-Pluronic to Deliver Curcumin for Infection-Free Wound Healing.

Skin is the largest protective tissue of the body and is at risk of damage. Hence, the design and development of wound dressing materials is key for tissue repair and regeneration. Although silk fibroin is a known biopolymer in tissue engineering, its degradation rate is not correlated with wound closure rate. To address this disadvantage, we mimicked the hierarchical structure of skin and also provided antibacterial properties; a hydrogel with globular structure consisting of silk fibroin, pluronic F127, and curcumin was developed. In this regard, the effect of pluronic and curcumin on the structural and mechanical properties of the hydrogel was studied. The results showed that curcumin affected the particle size, crystallinity, and ultimate elongation of the hydrogels. In vitro assays confirmed that the hydrogel containing curcumin is not cytotoxic while the diffused curcumin and pluronic provided a considerable bactericidal property against Methicillin-resistant Staphylococcus aureus. Interestingly, presence of pluronic caused more than a 99% reduction in planktonic and adherent bacteria in the curcumin-free hydrogel groups. Moreover, curcumin improved this number further and inhibited bacteria adhesion to prevent biofilm formation. Overall, the developed hydrogel showed the potential to be used for skin tissue regeneration.

Dynamical analysis of methicillin-resistant Staphylococcus aureus infection in North Cyprus with optimal control: prevalence and awareness.

The number of Methicillin-resistant Staphylococcus aureus (MRSA) cases in communities and hospitals is on the rise worldwide. In this work, a nonlinear deterministic model for the dynamics of MRSA infection in society was developed to visualize the significance of awareness in interventions that could be applied in the prevention of transmission with and without optimal control. Positivity and uniqueness were verified for the proposed corruption model to identify the level of resolution of infection factors in society. Furthermore, how various parameters affect the reproductive number R 0 and sensitivity analysis of the proposed model was explored through mathematical techniques and figures. The global stability of model equilibria analysis was established by using Lyapunov functions with the first derivative test. A total of seven years of data gathered from a private hospital consisting of inpatients and outpatients of MRSA were used in this model for numerical simulations and for observing the dynamics of infection by using a non-standard finite difference (NSFD) scheme. When optimal control was applied as a second model, it was determined that increasing awareness of hand hygiene and wearing a mask were the key controlling measures to prevent the spread of community-acquired MRSA (CA-MRSA) and hospital-acquired MRSA (HA-MRSA). Lastly, it was concluded that both CA-MRSA and HA-MRSA cases are on the rise in the community, and increasing awareness concerning transmission is extremely significant in preventing further spread.

Brief Report: Nasal colonization with Staphylococcus aureus and methicillin resistant Staphylococcus aureus among community-dwelling older adults with comorbidities seeking follow-up medical care in Central Sri Lanka.

Older adults are more severely affected by infections caused by drug-resistant bacteria including Methicillin-Resistant Staphylococcus aureus (MRSA). We aimed to identify the MRSA colonization rates and associated factors among older adults aged more than 65-years-old. Among the 309 recruited, 152 (49.2 %) were males. Self-collected nasal swabs were used to isolate Staphylococcus aureus and MRSA with routine microbiological methods. Staphylococcus aureus was isolated from 36 (11.7 %) participants while 11 (3.6 %) were colonized with MRSA. We identified a significant association between the male sex and MRSA colonization (P=0.028, Chi-square test). However, this needs careful interpretation given the smaller number of outcome events. Other factors studied had no statistically significant association with MRSA colonization.

REGECEL (an Oxidized Regenerated Cellulose) Provides Superior Bioactivity Effect on Microorganisms.

Introduction: Patients who need to be readmitted to the hospital because of complications from infections or require long-term care and rehabilitation face substantial financial hardships. To ensure the safety of patients undergoing surgery, it is crucial to implement measures that prevent wound infections before and after the procedure. Antibacterial wound dressings are essential to prevent infections during surgical procedures. There are various types of antibacterial wound dressings available on the market, such as silver-based dressings, hydrocolloid dressings, polyhexamethylene biguanide, alginate dressings, collagen-based dressings, and iodine-based dressings. Methods: We used each type (standard, knit, fibril, and non-woven) of a commercial brand of oxidized regenerated cellulose (ORC) called Regecel to test bacterial growth. The choice of antibacterial wound dressing depends on the type of wound being treated. Different bacterial strains require specific culture conditions to thrive and grow in laboratory settings. To obtain accurate and reliable results, it is vital to follow the precise culture conditions required for each bacterial strain. Results: The evaluation of ORC highlighted its potential to inhibit bacterial growth, showing promising results against various bacterial strains and Candida albicans. Different variants of ORC, such as Regecel, have demonstrated impressive capacity to hinder the growth of 32 distinct bacterial strains, with inhibition rates ranging from 40-100%. These bacteria include methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus (VRE), and penicillin-resistant Streptococcus pneumoniae. Conclusion: This study supports the usage and development of ORC (Regecel) as an innovative approach to treating bacterial infections.

Synergistic interaction between Chlorella vulgaris extract and Origanum elongatum essential oil against methicillin-resistant Staphylococcus aureus.

The massive emergence of antimicrobial resistance in recent decades has rendered the use of a single-agent strategy ineffective. Consequently, the combination of different therapeutic agents has emerged as a promising new approach. The aim of the present study was to investigate the combined effect of Chlorella vulgaris methanol extract (CVME) and Origanum elongatum essential oil (OEEO) on methicillin-resistant Staphylococcus aureus (MRSA). Thus, the antibacterial activity of OEEO and CVME on Escherichia coli, Staphylococcus aureus, and MRSA was evaluated using the agar well diffusion and broth microdilution methods. The killing activity of CVME and OEEO, individually and in combination, on MRSA ATCC 43300 was tested using the time-kill assay. The synergistic effect was examined by determining the fractional inhibitory concentration index (FICI) using the checkerboard test. The results showed very significant antibacterial activity against all the bacteria tested, for both OEEO and CVME, with minimum inhibitory concentrations (MICs) ranging from 0.125 to 0.25% (v/v) for OEEO and from 3.12 to 6.25 mg mL-1 for CVME. Minimum bactericidal concentration (MBC) values for OEEO and CVME were in the range 0.125-0.5% (v/v) and 6.25-12.5 mg mL-1, respectively. The inhibition zones associated with OEEO were distinctly greater than those associated with CVME for all the bacteria examined. When used individually, the time-kill curves of OEEO and CVME revealed a dose-dependent effect on MRSA proliferation. Compared with controls, both agents were able to prolong the latent phase of growth curves and decelerate bacterial growth. The killing effect of OEEO on MRSA was considerably higher than that observed with CVME. OEEO prevented MRSA proliferation at only 1/2 of its MIC, while the CVME did so at 2 times its MIC. The combination of OEEO with CVME demonstrated a synergistic effect against MRSA, with a FIC index value of 0.49. The findings therefore suggest that the combination of C. vulgaris methanol extract and O. elongatum essential oil at very low doses may be promising anti-MRSA candidates. A search of the published literature revealed that, to our knowledge, no studies have yet been carried out on the antibacterial potential of combining essential oils and microalgae extracts in the fight against MRSA.

"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.

Persistent Methicillin-Resistant Staphylococcus aureus (MRSA) Nares Test Positivity During Initial Days of Systemic Anti-Staphylococcal Antimicrobial Therapy.

The typical duration of positive nucleic acid tests for methicillin-resistant Staphylococcus aureus (MRSA) in the nares of patients receiving systemic anti-MRSA antimicrobials is unknown. In this study, hospitalized adult patients with an initial positive MRSA nares nucleic acid test prescribed systemic anti-MRSA antimicrobials had follow-up testing done 48-96 hours later. A positive follow-up test was detected in 100/113 (88.5%), indicating that MRSA nares DNA tests still have utility for screening after patients have initiated anti-MRSA therapy.

Exploring Naphthoquinone and Anthraquinone Derivatives as Antibiotic Adjuvants Against Staphylococcus aureus Biofilms: Synergistic Effects of Menadione.

Given the ability of Staphylococcus aureus to form biofilms and produce persister cells, making infections difficult to treat with antibiotics alone, there is a pressing need for an effective antibiotic adjuvant to address this public health threat. In this study, a series of quinone derivatives were evaluated for their antimicrobial and antibiofilm activities against methicillin-susceptible and methicillin-resistant S. aureus reference strains. Following analyses using broth microdilution, growth curve analysis, checkerboard assay, time-kill experiments, and confocal laser scanning microscopy, menadione was identified as a hit compound. Menadione exhibited a notable antibacterial profile (minimum inhibitory concentration, MIC = 4‒16 µg/ml; minimum bactericidal concentration, MBC = 256 µg/ml) against planktonic S. aureus and its biofilms (minimum biofilm inhibitory concentration, MBIC50 = 0.0625‒0.25 µg/ml). When combined with oxacillin, erythromycin, and vancomycin, menadione exhibited a synergistic or additive effect against planktonic cells and biofilms of two S. aureus reference strains and six clinical isolates, highlighting its potential as a suitable adjuvant for further development against S. aureus biofilm-associated infections.

A higher area under the concentration-time curve/minimum inhibitory concentration target as a potential prognostic factor for vancomycin treatment of methicillin-resistant Staphylococcus aureus meningitis: A case report.

The area under the concentration-time curve (AUC)/minimum inhibitory concentration (MIC) - guided approach is recommended for vancomycin therapeutic drug monitoring in severe methicillin-resistant Staphylococcus aureus (MRSA) infection. However, evidence regarding the efficacy of vancomycin AUC-guided strategies for the treatment of systemic infections is limited. This case report describes the successful treatment of MRSA meningitis, with vancomycin using a higher AUC/MIC target. A 61-year-old woman who underwent ventriculoperitoneal (VP) shunt placement for subarachnoid hemorrhage, developed MRSA meningitis due to shunt infection. Vancomycin was administered intravenously, with concurrent monitoring of serum and cerebrospinal fluid (CSF) vancomycin concentrations and AUC/MIC. On post-operative day (POD) 24 of VP shunt placement, the vancomycin trough concentration and AUC/MIC were 12.0 µg/mL and 515, respectively, with persistently positive CSF culture. On POD 28, the trough concentration and AUC/MIC were 18.6 µg/mL and 610, respectively. There were no major adverse events, and CSF culture turned negative on POD 30. The vancomycin CSF-to-serum ratio was approximately 41 %. For patients with MRSA meningitis, we suggest an optimal therapeutic range with a vancomycin AUC/MIC target near the upper limit of the therapeutic window.

Isolation of community-associated methicillin-resistant Staphylococcus aureus (MRSA) sequence type (ST) 30 from house rats (Rattus tanezumi) in Hong Kong.

Methicillin-resistant Staphylococcus aureus (MRSA) is of major public health concern due to its resistance to multiple antibiotics. This resistance has been observed in various settings, including hospitals and communities, and has been detected in both animals and humans. Although peridomestic rat species (Rattus spp.) are well described reservoirs of several human pathogens and antimicrobial resistant bacteria, little is known about their role in MRSA epidemiology. In order to investigate whether Rattus spp. in Hong Kong are potential carriers of MRSA, 221 rats were caught from various ecological areas and nasopharyngeal samples were cultured on MRSA selective media. Genotypic characteristics of MRSA were confirmed by whole genome sequencing. Two clonal sequence type (ST) 30 MRSA isolates, harbouring mecA on staphylococcal chromosome cassette (SCC) mec type IVc, were cultured from two house rats (Rattus tanezumi) caught in two densely populated urban areas. To the best of the authors' knowledge, this is the first detection of community-associated (CA)-MRSA strain ST30 SCCmec IVc in peridomestic rodents in Hong Kong and globally. Our finding indicates that house rats can be carriers of MRSA strains that are widely distributed in the community.

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.

Low concentrations of tetrabromobisphenol A promote the biofilm formation of methicillin-resistant Staphylococcus aureus.

The effect and underlying mechanism of tetrabromobisphenol A (TBBPA), a plastic additive, on biofilm formation of methicillin-resistant Staphylococcus aureus (MRSA USA300) remain unknown. This study first investigated the impact of different concentrations of TBBPA on the growth and biofilm formation of USA300. The results indicated that a low concentration (0.5 mg/L) of TBBPA promoted the growth and biofilm formation of USA300, whereas high concentrations (5 mg/L and 10 mg/L) of TBBPA had inhibitory effects. Further exploration revealed that the low concentration of TBBPA enhance biofilm formation by promoting the synthesis of extracellular proteins, release of extracellular DNA (eDNA), and production of staphyloxanthin. RTqPCR analysis demonstrated that the low concentration of TBBPA upregulated genes associated with extracellular protein synthesis (sarA, fnbA, fnbB, aur) and eDNA formation (atlA) and increased the expression of genes involved in staphyloxanthin biosynthesis (crtM), suggesting a potential mechanism for enhanced resistance of USA300 to adverse conditions. These findings shed light on how low concentrations of TBBPA facilitate biofilm formation in USA300 and highlight the indirect impact of plastic additives on pathogenic bacteria in terms of human health. In the future, in-depth studies about effects of plastic additives on pathogenicity of pathogenic bacteria should be conducted. CAPSULE: The protein and eDNA contents in biofilms of methicillin-resistant Staphylococcus aureus are increased by low concentrations of TBBPA.