Search Results (71)

The repurposing potential of Efavirenz (EFV), a clinically established non-nucleoside reverse transcriptase inhibitor, was comprehensively evaluated for its in vitro antibacterial effect either alone or in combination with other antibacterial agents on several Gram-positive clinical strains showing different antibiotic resistance profiles. The binding potential assessed by an in silico study included Penicillin-binding proteins (PBPs) and WalK membrane kinase. Despite the relatively high minimum inhibitory concentration (MIC) limiting the use of EFV as a single antibacterial agent, it exhibits significant synergistic activity at sub-MIC levels when paired with various antibiotics against Enterococcus species and Staphylococcus aureus. EFV showed restored sensitivity of β-lactams against Methicillin-resistant S. aureus (MRSA). It increased the effectiveness of antibiotics tested against Methicillin-sensitive S. aureus (MSSA). It also helped to overcome the intrinsic resistance barrier for several antibiotics in Enterococcus spp. In silico binding studies aligned remarkably with experimental antimicrobial testing results and highlighted the potential of EFV to direct the engagement of PBPs with moderate to strong binding affinities (pK_a 5.2–6.1). The dual-site PBP2 binding mechanism emerged as a novel inhibition strategy, potentially circumventing resistance mutations. Special attention should be paid to WalK binding predictions (pK_a = 4.94), referring to the potential of EFV to interfere with essential regulatory pathways controlling cell wall metabolism and virulence factor expression. These findings, in general, suggest the possibility of EFV as a promising lead for the development of new antibacterial agents. Full article

Staphylococcus aureus infections are an important cause of morbidity and mortality among patients in intensive care units (ICUs), particularly those with multiple comorbidities and critical conditions. Methicillin-resistant S. aureus (MRSA) and methicillin-sensitive S. aureus (MSSA) strains differ in resistance, clinical behavior, and prognoses, making it important to understand their effects on clinical outcomes. Comparing clinical outcomes of MRSA and MSSA infections is important. This retrospective cohort study analyzed ICU patients with confirmed S. aureus infections at a quaternary care hospital. Demographic, clinical, and comorbidity data were collected. Poisson regression was used to analyze 7-day mortality and identify adjusted risk factors. Seven-day mortality was higher in patients with MSSA than MRSA infections, with an adjusted relative risk for MRSA of 0.380 (95% confidence interval: 0.15–0.95; p = 0.039). Independent risk factors for mortality included lack of an infectious disease consultation, vascular comorbidities, such as peripheral vascular disease and cerebrovascular events, chronic kidney disease, and inotropic support requirement. Patients with MRSA infections required significantly longer ventilatory support (mean 43.5 days vs. 13 days for MSSA; p = 0.019). Staphylococcus aureus infections in ICU patients were associated with poor outcomes, particularly in patients without infectious disease consultation and those with vascular comorbidities. Mortality differences between MRSA and MSSA highlight the importance of appropriate empiric therapy and standardized protocols incorporating infectious disease consultation to improve outcomes in critically ill patients. Full article

Staphylococcus aureus are frequently associated with biofilm formation on intravascular devices. Biofilms limit antimicrobial penetration and promote phenotypic resistance, challenging conventional treatment strategies. Vancomycin (VAN) and gentamicin (GEN) have been used clinically, but their combined antibiofilm activity remains underexplored. This study evaluates the efficacy of VAN and GEN, alone and in combination, against biofilms formed by methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-sensitive S. aureus (MSSA) on polyurethane. MICs were determined for VAN and GEN. Biofilm biomass and metabolic activity were quantified using crystal violet and MTT assays, respectively. Biofilm viability was assessed through fluorescence microscopy and a modified Calgary Biofilm Device. A continuous-flow peristaltic model was developed to test treatment under simulated catheter conditions. While monotherapy with VAN or GEN had modest effects, their combination significantly reduced biomass and metabolic activity. VAN 20 mg/L + GEN 8 mg/L and VAN 40 mg/L + GEN 8 mg/L achieved over 70% reduction in MRSA biofilm viability and complete eradication in MBEC assays. Dynamic model assays confirmed biofilm reduction with combination therapy. The combination of VAN/GEN exhibits synergistic antibiofilm activity against S. aureus, particularly MRSA. These findings support its potential application in catheter salvage strategies, including antibiotic lock therapy. Full article

Methicillin-resistant Staphylococcus aureus (MRSA) is a devastating global health concern. Hypervirulent strains are on the rise, causing morbidities and mortalities worldwide. In tertiary care hospitals, critically ill patients, those undergoing invasive procedures, and pediatric and geriatric patients are at risk. It is not fully clear how strains adapt and specialize in humans and emerge despite the well-established commonality of the S. aureus genome from humans and animals. This study investigates the influence of age-, gender-, and source-specific profiles (clinical, intensive care unit (ICU vs. non-ICU)) on the evolution of hospital-associated (HA)-MRSA versus community-associated (CA)-MRSA lineages. A total of 253 non-duplicate S. aureus isolates were obtained from May 2023 to March 2025. The patients were stratified by age and gender in ICUs and non-ICUs. Standard microbiology methods and Clinical and Laboratory Standards Institute (CLSI) guidelines were used for identification and susceptibility testing, with cefoxitin and oxacillin disk diffusions and molecular diagnosis confirming MRSA. Mann–Whitney U and Chi-square tests assessed the demographic distributions, clinical specimen sources, and MRSA/methicillin-sensitive S. aureus (MSSA) prevalence. Of 253, 41.9% originated from ICUs (71% male; 29% female) and 58.1% from non-ICU wards (64% male; 36% female). In both settings, MRSA colonized the two extremes of age (10–29 and 70+) for males and females, with different mid-life peaks or declines by gender. However, the overall demographic distribution did not differ significantly between the ICU and non-ICU groups (p = 0.287). Respiratory specimens constituted 37% and had the highest MRSA rate (42%), followed by blood (24.5%) and wounds (10.3%). In contrast, MSSA dominated wounds (20.3%). Overall, 73.9% were resistant to cefoxitin and cefotaxime, whereas vancomycin, linezolid, daptomycin, and tigecycline remained highly effective. Younger non-ICU patients (10–29) had higher MSSA, whereas older ICU ones showed pronounced HA-MRSA profiles. By the virtue of methicillin resistance, all MRSA were classified as multidrug resistance. Thus, MRSA colonization of the two extremes of life mostly in ICU seniors and the dominance of invasive MSSA and CA-MRSA patterns in non-ICU youth imply early age- and gender-specific adaptations of the three lineages. MRSA colonizes both ICU and non-ICU populations at extremes of age and gender specifically. High β-lactam resistance underscores the importance of robust stewardship and age- and gender-specific targeting in screening. These findings also indicate host- and organ-specificity in the sequalae of MSSA, CA-MRSA, and HA-MRSA evolutionary dynamics, emphasizing the need for continued surveillance to mitigate MRSA transmission and optimize patient outcomes in tertiary care settings. Full article

The rising prevalence of antibiotic resistance underscores the need for localized drug delivery systems that minimize systemic exposure. Autologous platelet concentrates (APCs), including concentrated platelet-rich fibrin (c-PRF) and liquid-phase concentrated growth factors (LPCGFs), have emerged as potential carriers for antimicrobial agents. This study aimed to evaluate the efficacy of c-PRF and LPCGF as carriers for three antibiotic formulations—amoxicillin with clavulanic acid, clindamycin, and a combination of amoxicillin with metronidazole—against methicillin-sensitive Staphylococcus aureus (MSSA), methicillin-resistant Staphylococcus aureus (MRSA), and Enterococcus faecalis (low-level natural resistance). The disk diffusion method was employed to incorporate antibiotics into both APC types, which were then applied to disks placed on bacterial cultures. The size of the inhibition zones was measured at 20-, 40-, 60-, and 80-h intervals. Every 20 h, the disks were transferred to a new Petri dish. Statistical analysis included Welch’s t-test and two-way ANOVA. c-PRF demonstrated superior performance as a carrier for amoxicillin and clindamycin, showing the presence of inhibition zones for up to 60 h. In contrast, LPCGF exhibited greater efficacy when used with the amoxicillin–metronidazole combination, particularly at higher concentrations. Both APCs showed limited effectiveness against E. faecalis when combined with clindamycin. The study confirms the suitability of autologous platelet concentrates as localized antibiotic delivery systems. The choice between c-PRF and LPCGF should be guided by the drug’s physicochemical properties and clinical application. APCs offer a promising alternative for targeted antimicrobial therapy in dental and surgical settings. Full article

Background/Objectives: Staphylococcus aureus is a leading cause of bacteraemia in Danish hospitals. Approximately 70% of clinical S. aureus isolates are penicillin-resistant, which is predominantly due to blaZ-mediated β-lactamase production. Methods: A collection of 489 S. aureus strains derived from bacteraemia were cultured and their genomes sequenced. Results: From this collection, 71% of isolates were methicillin-susceptible S. aureus (MSSA) harbouring blaZ. While most isolates contained the blaZ gene belonging to the well-characterised A, B, C and D variants, three strains (1%) produced a BlaZ protein characterised by having threonine residues on both positions 128 and 216 and, therefore, belonged to neither of the established blaZ variants. We named this variant, variant F. We report that clinical isolates expressing blaZ variant F were resistant to oxacillin. The β-lactamase production phenotype in isolates carrying either of the A, B, C or D variants was only weakly discernible on MIC gradient strip and disk diffusion tests. When the β-lactamases were expressed either from a T7 promoter or from their endogenous promoters in Escherichia coli, variant F was significantly better at degrading ampicillin than variant A. We also showed that variant F conferred oxacillin resistance when expressed in an isogenic S. aureus strain, while variant A did not. Finally, we demonstrated that the F variant threonine 216 played a role in the enzyme’s superior activity. Conclusions: Our findings demonstrate that the new F variant of BlaZ is sufficient to render S. aureus a BORSA strain, which is superior in the degradation of common anti-staphylococcal β-lactam antibiotics, such as benzylpenicillin, cloxacillin, and oxacillin. It is sensitive to β-lactamase inhibitors and rapidly degrades nitrocefin. We provide a genetic explanation for the borderline oxacillin-resistant S. aureus (BORSA) phenotype. Full article

Since its standardization, clinical antimicrobial susceptibility testing (AST) has relied upon a standard medium, Mueller-Hinton Broth/Agar (MHB/A), to determine antibiotic resistance. However, this microbiologic medium bears little resemblance to the host milieu, calling into question the physiological relevance of resistance phenotypes it reveals. Recent studies investigating antimicrobial susceptibility in mammalian cell culture media, a more host-mimicking environment, demonstrate that exposure to host factors significantly alters susceptibility profiles. One such factor is bicarbonate, an abundant ion in the mammalian bloodstream/tissues. Importantly, bicarbonate sensitizes methicillin-resistant Staphylococcus aureus (MRSA) to early-generation β-lactams used for the treatment of methicillin-susceptible S. aureus (MSSA). This “NaHCO₃-responsive” phenotype is widespread among US MRSA USA300/CC8 bloodstream and skin and soft tissue infection isolates. Translationally, β-lactam therapy has proven effective against NaHCO₃-responsive MRSA in both ex vivo simulated endocarditis vegetation (SEV) and in vivo rabbit infective endocarditis (IE) models. Mechanistically, bicarbonate appears to influence mecA expression and PBP2a production/localization, as well as key elements for PBP2a functionality, including the PBP2a chaperone PrsA, components of functional membrane microdomains (FMMs), and wall teichoic acid (WTA) synthesis. The NaHCO₃-responsive phenotype highlights the critical role of host factors in shaping antibiotic susceptibility, emphasizing the need to incorporate more physiological conditions into AST protocols. Full article

Background/Objectives: The growing resistance of bacteria to antibiotics is a serious problem in health care. The present study aims to assess the drug resistance of Staphylococcus aureus, Enterococcus faecium, Enterococcus faecalis and Streptococcus pneumoniae isolated from infections in a multispecialty hospital over a 6-year period. Methods: Identification and antimicrobial susceptibility testing were performed using the VITEK^®2 automated system (Biomerieux). Results and Conclusions: Based on data from the analyzed hospital, MRSA strains were the etiological factor of 18–28% of S. aureus infections. In each year from 2017 to 2022, the percentage of MSSA strains steadily exceeded the number of MRSA strains. The MRSA strains isolated show significant sensitivity to antibiotic groups other than β-lactams, such as aminoglycosides, tetracyclines, cotrimoxazole, linezolid and vancomycin. Ciprofloxacin is the antibiotic to which S. aureus displays the second-highest resistance, after methicillin. In the case of MRSA strains, almost 100% lack of sensitivity to quinolines was found. An increase in the number of infections caused by strains of the Enterococcus genus was observed. For E. faecium strains, the percentage of vancomycin-resistant strains reached as much as 41% in 2018. Among the resistant strains in E. faecalis, VREs (Vancomycin-Resistant Enterococci) slightly predominate, while GREs (Glycopeptide-Resistant Enterococci) are much more prevalent in E. faecium. The data show that the percentage of S. pneumoniae strains insensitive to ampicillin ranged from 6% to 17%. In 2017, the percentage of strains resistant to this antibiotic reached 17%, while in 2022, their share decreased to 9%. In 2021–2022, the percentage of strains resistant to erythromycin was as high as 33%. This resistance is related to the MLS (macrolides, lincosamides, streptogramines B) mechanism. An increase in S. pneumoniae resistance to 100% was observed in 2017 and 2019. In the analyzed six-year period, from 2020 (beginning of the pandemic), in some groups of antibiotics, a significant increase in consumption in DDD/100 person-days was recorded. This is most visible in the case of fluoroquinolones. The analysis carried out will increase the effectiveness of empirical therapy in the hospital and the prudent use of antibiotics to limit the selection of multidrug-resistant strains. Full article

Staphylococcus aureus is a human pathogen responsible for a wide range of diseases, such as skin and soft tissue infections, pneumonia, toxic shock syndrome, and urinary tract infections. Methicillin-resistant S. aureus (MRSA) is a well-known pathogen with consistently high mortality rates. Detecting the mecA resistance gene and phenotypical profile to β-lactams allows for the differentiation of MRSA from methicillin-susceptible S. aureus (MSSA) isolates. In this study, we characterized 57 S. aureus clinical isolates for β-lactam susceptibility and mecA presence. We classified 52.63% as MRSA and 45.61% as MSSA. However, some isolates evidenced different oxacillin resistance profiles, such as borderline oxacillin-resistant or modified S. aureus (BORSA/MODSA). The cefazolin inoculum effect (CzIE) was established for these samples, emphasizing the relevance of these isolates as a source of therapeutic failure. We also performed the detection of the Panton-Valentine Leucocidin virulence genes as well as the S. aureus spa-type clonality. As expected, spa-types t002 and t008 were the most prevalent clones, demonstrating the success of well-established clones. These findings emphasize the importance of establishing sensitivity profiles, especially in isolates with poor resistance mechanisms, to determine their prevalence and their impact on public health. Full article

Introduction: An ambulance used by an emergency medical service team is the workplace of specialised medical personnel, providing daily transportation for patients in life-threatening conditions, from all walks of life, with numerous diseases and injuries. MRSA (methicillin-resistant Staphylococcus aureus) strains are classified as Gram-positive cocci, characterised primarily by their multidrug resistance. Infections caused by S. aureus have a low treatment success rate and are associated with persistent carrier state. This study aimed to isolate MRSA and MSSA (methicillin-sensitive Staphylococcus aureus) in the emergency vehicle and determine drug resistance of these isolates. Materials and Methods: This study involved an ambulance vehicle operated in central Poland. A total of 39 swabs were taken and evaluated from inside the ambulance on permanent duty. The isolates were analysed using catalase and coagulase assays, Gram staining, culturing on Chapman medium, growth evaluation on agar with 5% sheep blood, and assessing the strains’ sensitivities to selected antibiotics. Material was collected from 13 designated points located in the medical compartment and driver’s cabin. Results: S. aureus bacteria were detected in 51.28% of the samples, 40% of which were MRSA strains. Despite the application of high disinfection standards for the interior of the ambulance, it was not possible to kill all S. aureus strains, which may be because the pathogens in question produce a biofilm that effectively allows them to survive on various surfaces, including those disinfected. Almost 100% of the MRSA isolates were resistant to antibiotics from the β-lactam group (penicillin, ticarcillin, cefotaxime, and cefoxitin), the macrolide group (erythromycin) and the lincosamide group (clindamycin). However, only a few MRSA strains proved resistant to streptomycin (12.5%) and ciprofloxacin (37.5%). β-lactam antibiotics, such as cefotaxime (100% resistant strains) and penicillin (58% resistant strains), were also ineffective against MSSA. Although MSSA isolates showed slight resistance to ticarcillin and erythromycin (33.3%) and clindamycin (25%), the remaining antibiotics proved effective (no resistant strains). Conclusions: Among the isolated strains, the greatest resistance to β-lactam antibiotics and erythromycin was observed. Multidrug-resistant strains of S. aureus were found in the emergency medical system. Even the MSSA strains detected in the studied ambulance showed resistance to some of the antibiotics used. The prevalence of S. aureus strains within ambulances indicates the need for a high hygiene level in daily prehospital work with patients. Full article

Background and Objectives: Staphylococcus aureus is a prominent component of the human flora; however, it can cause various pathological conditions. The emergence of methicillin-resistant S. aureus (MR-SA) has been significantly influenced by the overuse and inappropriate administration of antibiotics. The frequency of MR-SA nasal colonization among healthcare workers (HCWs) is increasing, and MR-SA is not restricted to hospital settings, with a notable rise in infections among individuals unrelated to HCWs. This study aimed to assess the prevalence of S. aureus nasal carriage among students at Government College University Faisalabad (GCUF), University of Agriculture Faisalabad (UAF), a Government School (GS), and a Private School (PS) to characterize the phenotypic traits of isolates and evaluate antimicrobial resistance profiles. Materials and Methods: A total of 1200 nasal swabs were inoculated on blood and mannitol salt agar, followed by phenotypic identification of S. aureus and MR-SA using biochemical tests. Antimicrobial susceptibility testing was conducted via the Kirby–Bauer disk diffusion method, and minimum inhibitory concentration (MIC) determination was performed using the broth dilution method. Additionally, nuc and mecA gene amplification through PCR aided in isolate identification. Results: The results revealed that 14% (168) of students harbored S. aureus in their nasal cavities, with 8.5% (102) carrying methicillin-sensitive S. aureus (MSSA) and 5.5% (66) carrying MR-SA. Male students exhibited higher S. aureus (57.7%) and MR-SA (21.4%) prevalence compared to females (42.3% and 17.9%, respectively). Urban students showed a higher S. aureus prevalence (54.2%), while rural students exhibited a higher MR-SA rate (22%). Overall, 80.3% of S. aureus isolates displayed resistance to erythromycin followed by fluoroquinolones (47.6%) and clindamycin (42.2%). All the S. aureus isolates, including MR-SA, remained susceptible to vancomycin and linezolid. PCR results revealed that 95.5% (63) of MR-SA isolates carried the mecA gene. Conclusions: The high prevalence of multi-drug-resistant (MDR) S. aureus raises significant public health concerns, with educational institutions potentially serving as reservoirs for bacterial transmission. The improper use of antibiotics contributes to bacterial resistance and increased infection rates. It is crucial to implement measures to prevent antibiotic misuse and develop comprehensive strategies within educational settings to effectively combat S. aureus and MR-SA prevalence. Full article

Recently, there has been a surge towards searching for primitive treatment strategies to discover novel therapeutic approaches against multi-drug-resistant pathogens. Endophytes are considered unexplored yet perpetual sources of several secondary metabolites with therapeutic significance. This study aims to isolate and identify the endophytic fungi from Annona squamosa L. fruit peels using morphological, microscopical, and transcribed spacer (ITS-rDNA) sequence analysis; extract the fungus’s secondary metabolites by ethyl acetate; investigate the chemical profile using UPLC/MS; and evaluate the potential antibacterial, antibiofilm, and antiviral activities. An endophytic fungus was isolated and identified as Aspergillus flavus L. from the fruit peels. The UPLC/MS revealed seven compounds with various chemical classes. The antimicrobial activity of the fungal ethyl acetate extract (FEA) was investigated against different Gram-positive and Gram-negative standard strains, in addition to resistant clinical isolates using the agar diffusion method. The CPE-inhibition assay was used to identify the potential antiviral activity of the crude fungal extract against low pathogenic human coronavirus (HCoV 229E). Selective Gram-positive antibacterial and antibiofilm activities were evident, demonstrating pronounced efficacy against both methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-sensitive Staphylococcus aureus (MSSA). However, the extract exhibited very weak activity against Gram-negative bacterial strains. The ethyl acetate extract of Aspergillus flavus L exhibited an interesting antiviral activity with a half maximal inhibitory concentration (IC₅₀) value of 27.2 µg/mL against HCoV 229E. Furthermore, in silico virtual molecular docking-coupled dynamics simulation highlighted the promising affinity of the identified metabolite, orienting towards three MRSA biotargets and HCoV 229E main protease as compared to reported reference inhibitors/substrates. Finally, ADME analysis was conducted to evaluate the potential oral bioavailability of the identified metabolites. Full article

The present study aimed to evaluate the in vitro antibacterial and antibiofilm activity of bacterial cellulose hydrogel produced by Zoogloea sp. (HYDROGEL) containing vancomycin (VAN) against bacterial strains that cause wound infections, such as multidrug-resistant (MDR) Staphylococcus aureus and Staphylococcus epidermidis. Initially, HYDROGEL was obtained from sugar cane molasses, and scanning electron microscopy (SEM) was performed to determine morphological characteristics. Then, VAN was incorporated into HYDROGEL (VAN-HYDROGEL). The antibacterial activity of VAN, HYDROGEL, and VAN-HYDROGEL was assessed using the broth microdilution method to determine the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) against methicillin-sensitive S. aureus (MSSA) ATCC 25923, methicillin-resistant S. aureus (MRSA) ATCC 33591, S. epidermidis INCQS 00016 (ATCC 12228), five clinical isolates of MRSA, and nine clinical isolates of methicillin-resistant S. epidermidis, following the Clinical and Laboratory Standards Institute (CLSI) guidelines. Additionally, the antibacterial activity of VAN, HYDROGEL, and VAN-HYDROGEL was studied using the time-kill assay. Subsequently, the antibiofilm activity of VAN, HYDROGEL, and VAN-HYDROGEL was evaluated using crystal violet and Congo red methods, as well as SEM analysis. VAN and VAN-HYDROGEL showed bacteriostatic and bactericidal activity against MRSA and methicillin-resistant S. epidermidis strains. HYDROGEL did not show any antibacterial activity. Analysis of the time-kill assay indicated that HYDROGEL maintained the antibacterial efficacy of VAN, highlighting its efficiency as a promising carrier. Regarding antibiofilm activity, VAN and HYDROGEL inhibited biofilm formation but did not demonstrate biofilm eradication activity against methicillin-resistant S. aureus and S. epidermidis strains. However, it was observed that the biofilm eradication potential of VAN was enhanced after incorporation into HYDROGEL, a result also proven through images obtained by SEM. From the methods carried out in this study, it was possible to observe that HYDROGEL preserved the antibacterial activity of vancomycin, aside from exhibiting antibiofilm activity and enhancing the antibiofilm effect of VAN. In conclusion, this study demonstrated the potential of HYDROGEL as a candidate and/or vehicle for antibiotics against MDR bacteria that cause wound infections. Full article

Bloodstream infections by bacteria, especially multidrug-resistant bacteria, remain a worldwide public health concern. We evaluated the antibacterial activity of ceftobiprole and comparable drugs against different bloodstream isolates and different sequence types of methicillin-resistant Staphylococcus aureus (MRSA) in China. We found that MRSA, methicillin-susceptible Staphylococcus aureus (MSSA), and methicillin-susceptible coagulase-negative Staphylococcus (MSCNS) displayed ceftobiprole sensitivity rates of >95%, which are similar to the rates for linezolid, daptomycin, and vancomycin. Of the tested MRCNS strains, 90.4% were sensitive to ceftobiprole. The sensitivities of ST59, ST398, and ST22 MRSA to ceftobiprole were higher than that of ST239. Ceftobiprole’s MIC_50/90 value against Enterococcus faecalis was 0.25/2 mg/L, whereas Enterococcus faecium was completely resistant to this drug. Ceftobiprole exhibited no activity against ESBL-positive Enterobacterales, with resistance rates between 78.6% and 100%. For ESBL-negative Enterobacterales, excluding Klebsiella oxytoca, the sensitivity to ceftobiprole was comparable to that of ceftazidime, ceftriaxone, and cefepime. The MIC_50/90 value of ceftobiprole against Pseudomonas aeruginosa was 2/16 mg/L, and for Acinetobacter baumannii, it was 32/>32 mg/L. Thus, ceftobiprole shows excellent antimicrobial activity against ESBL-negative Enterobacterales and Pseudomonas aeruginosa (comparable to that of ceftazidime, ceftriaxone, and cefepime); however, it is not effective against ESBL-positive Enterobacterales and Acinetobacter baumannii. These results provide important information to clinicians. Full article

Infections caused by Staphylococcus aureus are particularly difficult to treat due to the high rate of antibiotic resistance. S. aureus also forms biofilms that reduce the effects of antibiotics and disinfectants. Therefore, new therapeutic approaches are increasingly required. In this scenario, plant waste products represent a source of bioactive molecules. In this study, we evaluated the antimicrobial and antibiofilm activity of the rice husk extract (RHE) on S. aureus clinical isolates. In a biofilm inhibition assay, high concentrations of RHE counteracted the formation of biofilm by S. aureus isolates, both methicillin-resistant (MRSA) and -sensitive (MSSA). The observation of the MRSA biofilm by confocal laser scanning microscopy using live/dead cell viability staining confirmed that the bacterial viability in the RHE-treated biofilm was reduced. However, the extract showed no or little biofilm disaggregation ability. An additive effect was observed when treating S. aureus with a combination of RHE and oxacillin/cefoxitin. In Galleria mellonella larvae treated with RHE, the extract showed no toxicity even at high concentrations. Our results support that the rice husk has antimicrobial and antibiofilm properties and could potentially be used in the future in topical solutions or on medical devices to prevent biofilm formation. Full article