Methicillin-resistant Research Articles

A COMPARATIVE STUDY OF ANTIMICROBIAL SENSITIVITY IN PATIENTS WITH ACUTE PYELONEPHRITIS AND EMPHYSEMATOUS PYELONEPHRITIS

Background: Urinary tract infections (UTIs) commonly affect men and can lead to serious complications such as acute pyelonephritis (APN) and emphysematous pyelonephritis (EPN). APN typically impacts the renal pelvis and parenchyma, often exacerbated by conditions like obesity, diabetes, or immunosuppression. EPN, characterized by gas formation within the renal tissues, is predominantly caused by Escherichia coli and Klebsiella pneumoniae. Objective: This study aims to identify the pathogens responsible for emphysematous pyelonephritis, compare their prevalence with acute pyelonephritis, and evaluate their antimicrobial sensitivity patterns. Methods: A comparative study was conducted over twelve months, from July 2023 to June 2024, involving 145 patients diagnosed with APN and EPN at the Institute of Kidney Disease, Peshawar. Urine samples were collected and cultured to determine the causative microorganisms and assess their antibiotic sensitivities. Data analysis was performed using SPSS 23. Results: Among the patients, 72.4% (n=105) were diagnosed with APN and 27.6% (n=40) with EPN. Escherichia coli was the most common pathogen in both conditions. Antimicrobial sensitivity testing showed high effectiveness of colistin (90.4%), amikacin (88.0%), piperacillin/tazobactam (82.4%), imipenem (82.4%), and gentamicin (82.4%) for APN. However, sensitivities were lower in EPN, reflecting a concerning rise in antimicrobial resistance. Conclusion: The prevalence of antimicrobial resistance, especially in EPN cases, poses significant challenges. Although colistin, aminoglycosides, and carbapenems remain largely effective, their misuse is contributing to increased resistance. Adhering to WHO guidelines for antimicrobial prescriptions is critical to manage and prevent the escalation of multidrug resistance.

Ferroptosis Inducers Erastin and RSL3 Enhance Adriamycin and Topotecan Sensitivity in ABCB1/ABCG2-Expressing Tumor Cells.

Acquired resistance to chemotherapeutic drugs is the primary cause of treatment failure in the clinic. While multiple factors contribute to this resistance, increased expression of ABC transporters-such as P-glycoprotein (P-gp), breast cancer resistance protein (BCRP), and multidrug resistance proteins-play significant roles in the development of resistance to various chemotherapeutics. We found that Erastin, a ferroptosis inducer, was significantly cytotoxic to NCI/ADR-RES, a P-gp-expressing human ovarian cancer cell line. Here, we examined the effects of both Erastin and RSL3 (Ras-Selected Ligand 3) on reversing Adriamycin resistance in these cell lines. Our results show that Erastin significantly enhanced Adriamycin uptake in NCI/ADR-RES cells without affecting sensitive cells. Furthermore, we observed that Erastin enhanced Adriamycin cytotoxicity in a time-dependent manner. The selective iNOS inhibitor, 1400W, reduced both uptake and cytotoxicity of Adriamycin in P-gp-expressing NCI/ADR-RES cells only. These findings were also confirmed in a BCRP-expressing human breast cancer cell line (MCF-7/MXR), which was selected for resistance to Mitoxantrone. Both Erastin and RSL3 were found to be cytotoxic to MCF-7/MXR cells. Erastin significantly enhanced the uptake of Hoechst dye, a well-characterized BCRP substrate, sensitizing MCF-7/MXR cells to Topotecan. The effect of Erastin was inhibited by 1400W, indicating that iNOS is involved in Erastin-mediated enhancement of Topotecan cytotoxicity. RSL3 also significantly increased Topotecan cytotoxicity. Our findings-demonstrating increased cytotoxicity of Adriamycin and Topotecan in P-gp- and BCRP-expressing cells-suggest that ferroptosis inducers may be highly valuable in combination with other chemotherapeutics to manage patients' cancer burden in the clinical setting.

Protective role of ABCC drug subfamily resistance transporters (ABCC1-7) in intestinal inflammation.

The ABCC subfamily contains thirteen members. Nine of these transporters are called multidrug resistance proteins (MRPs). The MRPs have been associated with developing ulcerative colitis (UC). This study aimed to evaluate the ABCC expression in UC patients and its role in a dextran sulfate sodium (DSS)-induced colitis mice model under 5-aminosalicylates or methylprednisolone treatment and compared with control without inflammation. DSS-induced colitis mice were treated with 5-aminosalicylates (50mg/kg 24h) or methylprednisolone (2mg/kg 24h). Human rectal biopsies were obtained from UC patients. The abcc-relative mRNA levels and protein expression were determined by RT-PCR and immunohistochemistry. abcc4, abcc5, and abcc6 mRNA levels were significantly increased in DSS-induced colitis compared to the other groups. The 5-aminosalicylate treatment dramatically increased the abcc2 and abcc3 mRNA levels vs. control. Methylprednisolone treatment increased abcc1 vs. DSS-induced colitis and colitis treated with 5-aminosalicylate. Immunohistochemical analysis revealed down-regulation of ABCC1/ABCC2/ABCC5/ABCC7 in mice colitis vs. control. Treatment with 5-aminosalicylate restored ABCC5 levels, while methylprednisolone restored ABCC2/ABCC5/ABCC7 in colitis mice at similar control levels. Relative mRNA levels of mrp1-5 were increased in active UC patients vs. control. ABCC2/ABCC4/ABCC7 were conspicuously expressed in the mucosa of 5-aminosalicylate and/or methylprednisolone-treated UC patients, while ABCC2/ABCC4/ABCC5/ABCC7 in submucosa, ABCC1/ABCC5/ABCC7 in muscular, and ABCC1/ABCC4/ABCC5/ABCC7 in serosa were expressed vs. controls. This is the first report about the differential up-regulation of the ABCC subfamily gene and protein expression in DSS-induced colitis under aminosalicylates or methylprednisolone treatment.

Stereospecific Resistance to N2-Acyl Tetrahydro-β-carboline Antimalarials Is Mediated by a PfMDR1 Mutation That Confers Collateral Drug Sensitivity.

Half the world's population is at risk of developing a malaria infection, which is caused by parasites of the genus Plasmodium. Currently, resistance has been identified to all clinically available antimalarials, highlighting an urgent need to develop novel compounds and better understand common mechanisms of resistance. We previously identified a novel tetrahydro-β-carboline compound, PRC1590, which potently kills the malaria parasite. To better understand its mechanism of action, we selected for and characterized resistance to PRC1590 in Plasmodium falciparum. Through in vitro selection of resistance to PRC1590, we have identified that a single-nucleotide polymorphism on the parasite's multidrug resistance protein 1 (PfMDR1 G293V) mediates resistance to PRC1590. This mutation results in stereospecific resistance and sensitizes parasites to other antimalarials, such as mefloquine, quinine, and MMV019017. Intraerythrocytic asexual stage specificity assays have revealed that PRC1590 is most potent during the trophozoite stage when the parasite forms a single digestive vacuole (DV) and actively digests hemoglobin. Moreover, fluorescence microscopy revealed that PRC1590 disrupts the function of the DV, indicating a potential molecular target associated with this organelle. Our findings mark a significant step in understanding the mechanism of resistance and the mode of action of this emerging class of antimalarials. In addition, our results suggest a potential link between resistance mediated by PfMDR1 and PRC1590's molecular target. This research underscores the pressing need for future research aimed at investigating the intricate relationship between a compound's chemical scaffold, molecular target, and resistance mutations associated with PfMDR1.

Comparison of Reported Antibiotic Treatment in Chicken Farming and Antibiotic-Resistant (E. coli) in Commercial Poultry Meat

This study investigates the prevalence and antimicrobial resistance of Escherichia coli in poultry meat sold in Al Bayda, Libya. A total of 37 chicken meat samples were analyzed for resistance to 12 antibiotics, using the disk diffusion method. The results indicated high resistance rates, particularly to ampicillin, ampicillin-sulbactam, cefazolin, and tetracycline, with 48% of the isolates exhibiting multidrug resistance. Conventionally reared poultry showed significantly higher resistance to gentamicin, commonly used in egg vaccines. The study found no significant differences in resistance across production categories, but brand-specific factors were strongly associated with resistance levels. These findings suggest that antibiotic use in poultry production, particularly in conventional systems, contributes to increased resistance, emphasizing the need for improved regulations and monitoring of antibiotic use across all stages of production to ensure food safety and reduce the spread of resistance.

Ceftobiprole activity against multidrug-resistant Staphylococcus aureus clinical isolates collected in the United States from 2016 through 2022.

Ceftobiprole was recently approved by the United States (US) Food and Drug Administration (FDA) for the treatment of adult patients with Staphylococcus aureus bacteremia, including right-side endocarditis, acute bacterial skin and skin structure infections, and community-acquired bacterial pneumonia in adults and pediatrics. Ceftobiprole is an advanced-generation cephalosporin approved in many countries for the treatment of adults with community-acquired pneumonia and hospital-acquired pneumonia, excluding ventilator-associated pneumonia. We evaluated the activities of ceftobiprole and comparators against methicillin-resistant S. aureus (MRSA) and multidrug-resistant (MDR) S. aureus clinical isolates. A total of 19,764 S. aureus isolates were collected from patients with various infection types at 37 US medical centers from 2016 to 2022. Susceptibility testing was performed by broth microdilution according to Clinical and Laboratory Standard Institutes (CLSI) standards. Isolates were categorized as MDR if they were nonsusceptible by CLSI criteria to ≥3 antimicrobials. Ceftobiprole was highly active against MRSA (n = 8,184; MIC50/90, 1/2 mg/L; 99.3% susceptible [S]) and MDR (n = 2,789; MIC50/90, 1/2 mg/L; 98.1%S) isolates and retained activity against 87.3% of ceftaroline-nonsusceptible isolates (n = 433; MIC50/90, 2/4 mg/L). Ceftobiprole demonstrated greater susceptibility rates than ceftaroline against all resistant subsets. Ceftobiprole was highly active against isolates nonsusceptible to clindamycin (98.0%S), daptomycin (100.0%S), doxycycline (98.2%S), erythromycin (99.5%S), gentamicin (98.1%S), levofloxacin (99.1%S), tetracycline (99.1%S), tigecycline (100.0%S), and trimethoprim-sulfamethoxazole (99.4%S) and isolates with decreased susceptibility to vancomycin (98.3%S).

Asymptomatic carriage and molecular characterization of Staphylococcus aureus in pre-clinical and clinical medical students.

Medical students are exposed to the hospital environment and patients during their studies, increasing the risk of exposure to virulent and antibiotic-resistant isolates of Staphylococcus aureus. The aim of the study is to determine the prevalence of Staphylococcus aureus among medical students who have varying levels of exposure to the hospital environment to provide valuable insights into the risk of colonization and transmission. Nasal swabs and fingerprints were obtained and cultured on a selective medium for staphylococci. The obtained isolates were confirmed as methicillin-sensitive S. aureus (MSSA) or methicillin-resistant (MRSA) using PCR. Antibiotic resistance, the presence of virulence genes including enterotoxin encoding genes, and spa typing were performed. Among pre-clinical students, MSSA was detected on the nose in 45.2% and on the fingerprints in 10.6% of the participants. Among clinical students, MSSA was detected on the nose in 42.0% and on the fingerprints in 25.4%. Only one MRSA isolate was obtained. Genes seg and sei were the most frequently detected in both student groups, with their presence in over 40% of isolates among clinical students. The eta and etb genes were mainly detected from the nose in both student groups. In pre-clinical students, S. aureus carrying eta gene occurred in 6.4% and etb in 8.5%. In clinical students, the occurrence was 5.1% for eta and 8.5% for etb. The tst gene was identified only in the nose and fingerprints of the clinical student group. The most frequently observed resistance was to clindamycin and erythromycin. In total 58 different spa types were identified. High rates of asymptomatic MSSA carriage were observed in both groups of medical students. Detected MSSA strains showed a high degree of genetic variability, with a number of them carrying the virulence and antibiotic resistance genes. Although students do not exhibit increased risk to their patient's, increased hygiene is required in asymptomatic carriage personnel. The overall prevalence of MRSA was low, with a minimal risk of spread.

A Bioinspired Virus-Like Mechano-Bactericidal Nanomotor for Ocular Multidrug-Resistant Bacterial Infection Treatment.

Multidrug-resistant (MDR) bacteria and their associated biofilms are major causative factors in eye infections, often resulting in blindness and presenting considerable global health challenges. Presently, mechano-bactericidal systems, which combine distinct topological geometries with mechanical forces to physically induce bacterial apoptosis, show promising potential. However, the physical interaction process between current mechano-bactericidal systems and bacteria is generally based on passive diffusion or Brownian motion and lacks the force required for biofilm penetration; thus, featuring low antibacterial efficacy. Here, a biomimetic mechano-bactericidal nanomotor (VMSNT) is synthesized by functionalizing COOH-PEG-phenylboronic acid (PBA) on virus-like mesoporous silica, with subsequent partial coating of Au caps. Enhanced by self-thermophoresis capabilities and virus-like topological shapes, VMSNT significantly improves mechanical antibacterial effects and biofilm penetration. In addition, scanning electron microscope (SEM) and confocal laser scanning microscope (CLSM)analyses demonstrate that VMSNT can precisely target bacteria within the infection microenvironment, facilitated by PBA's ability to recognize and bind to the peptidoglycan on bacterial surfaces. Remarkably, VMSNT is also effective in eliminating MDR bacteria and reducing inflammation in mice models of methicillin-resistant Staphylococcus aureus (MRSA)-infected keratitis and endophthalmitis, with minimal adverse effects. Overall, such a nanomotor presents a promising approach for addressing the challenges of ocular MDR bacterial infections.

Exploring target selectivity in designing and identifying PI3Kα inhibitors for triple negative breast cancer with fragment-based and bioisosteric replacement approach

Triple-negative breast cancer (TNBC) is one of the most fatal malignancies in the world, accounting for 42% of all deaths due to metastasis. The significant development is hindered by the multi-drug resistance and poor patient compliance. PIK3CA gene mutation is one of the important causes of TNBC, which causes dysregulation of the cell cycle and cell proliferation. PI3Kα selective inhibition can decrease the TNBC by a significant level with minimal off-target effects. Novel compounds with high selectivity towards PI3Kα are crucial for treating TNBC. After extensive literature analysis, it was observed that fragment-based drug discovery, combined with structure-based virtual screening and bioisosteric replacement strategy, could provide a novel way for hit-to-lead optimization. The present study focussed on the fragment-based direct linking of 11269 moieties of the ChemDiv fragment library, - to generate novel moieties and further screened them using molecular docking, MMGBSA, and target selectivity analysis. Further, the top 2 moieties – Djh1 and Djh2 were selected after MMGBSA analysis and target selectivity prediction towards kinase. Further induced fit docking (IFD) analysis, DFT analysis, and MD simulation were employed to establish that – Djh1 and Djh2 could act as potential hit molecules for selective inhibition of PI3Kα. Further bioisosteric replacement, docking analysis, and target selectivity analysis were performed with the bioisosteres. The top two bioisosteres of Djh1 – Compound 10, Compound 06 represented excellent efficacy and selectivity towards PI3Kα in the treatment of TNBC after analysis of ADMET analysis. Further, in vitro and in vivo analysis might prove the effectiveness of the hit compounds.

Extended spectrum betalactamase and Carbapenemase producing gram negative bacteria from healthcare workers gowns at Debre Berhan Comprehensive Specialized Hospital, Ethiopia

Extended-spectrum beta-lactamase (ESBL) and carbapenemase-producing (CP) gram-negative bacteria are the major public health concerns. Gowns used by healthcare workers (HCWs) in daily practice are a source of hospital-acquired infections in hospital settings. The study aimed to determine the prevalence of extended-spectrum beta-lactamase and carbapenemase-producing gram-negative bacteria from gowns of healthcare workers at Debre Berhan Comprehensive Specialized Hospital, Amhara Regional State, Ethiopia. A hospital-based cross-sectional study was conducted from August to October 2022. A total of 226 swab samples were collected from gowns of HCWs and cultured on MacConkey agar. Bacterial identifications were done by standard biochemical tests. Screening for ESBL and carbapenemase production was done using CHROME agar. Confirmation of ESBL and carbapenemase production was done by the combination disk method and modified carbapenem inactivation method, respectively. Data were analyzed by using SPSS version 25. The overall contamination rate of gowns was 46.9% (106/226). Among 226 swab samples, a total of 117 (51.7%) gram-negative bacteria were isolated. Among these, the most frequent isolates were E. coli, accounted 36 (30.8%) followed by K. pneumoniae, 26(22.2%). The overall multi-drug resistance (MDR) rate was 65 (55.6%). Of the 117 isolates, 17(14.5%) and 12(10.3%) were ESBL and carbapenemase producers respectively. Gown type (p = 0.041), laundering practice (p = 0.045), number of gowns (p = 0.002), and gown washing frequency per week (p = 0.017).were significantly associated with bacterial contamination of gowns. In this study, the prevalence of ESBL and CP Gram-negative bacteria from gowns of healthcare workers was found to be alarming. Therefore, strict infection prevention and control practices, as well as good hygienic practices, should be implemented to reduce and prevent cross-contamination and the spread of antimicrobial-resistant strains in hospital settings.

Molecular Mechanisms of Dietary Compounds in Cancer Stem Cells from Solid Tumors: Insights into Colorectal, Breast, and Prostate Cancer.

Cancer stem cells (CSC) are known to be the main source of tumor relapse, metastasis, or multidrug resistance and the mechanisms to counteract or eradicate them and their activity remain elusive. There are different hypotheses that claim that the origin of CSC might be in regular stem cells (SC) and, due to accumulation of mutations, these normal cells become malignant, or the source of CSC might be in any malignant cell that, under certain environmental circumstances, acquires all the qualities to become CSC. Multiple studies indicate that lifestyle and diet might represent a source of wellbeing that can prevent and ameliorate the malignant phenotype of CSC. In this review, after a brief introduction to SC and CSC, we analyze the effects of phenolic and non-phenolic dietary compounds and we highlight the molecular mechanisms that are shown to link diets to CSC activation in colon, breast, and prostate cancer. We focus the analysis on specific markers such as sphere formation, CD surface markers, epithelial-mesenchymal transition (EMT), Oct4, Nanog, Sox2, and aldehyde dehydrogenase 1 (ALDH1) and on the major signaling pathways such as PI3K/Akt/mTOR, NF-κB, Notch, Hedgehog, and Wnt/β-catenin in CSC. In conclusion, a better understanding of how bioactive compounds in our diets influence the dynamics of CSC can raise valuable awareness towards reducing cancer risk.

Effect of Fecal Microbiota Transplant on Antibiotic Resistance Genes Among Patients with Chronic Pouchitis.

Pouchitis is common among patients with ulcerative colitis (UC) who have had colectomy with ileal pouch-anal anastomosis. Antibiotics are first-line therapy for pouch inflammation, increasing the potential for gut colonization with multi-drug resistant organisms (MDRO). Fecal microbial transplant (FMT) is being studied in the treatment of pouchitis and in the eradication of MDRO. Prior work using aerobic antibiotic culture disks suggests that some patients with chronic pouchitis may regain fluoroquinolone sensitivity after FMT. However, gut MDRO include anaerobic, fastidious organisms that are difficult to culture using traditional methods. We aimed to assess whether FMT reduced the abundance of antibiotic resistance genes (ARG) or affected resistome diversity, evenness, or richness in patients with chronic pouchitis. We collected clinical characteristics regarding infections and antibiotic exposures for 18 patients who had previously been enrolled in an observational study investigating FMT as a treatment for pouchitis. Twenty-six pre- and post-FMT stool samples were analyzed using FLASH (Finding Low Abundance Sequences by Hybridization), a CRISPR/Cas9-based shotgun metagenomic sequence enrichment technique that detects acquired and chromosomal bacterial ARGs. Wilcoxon rank sum tests were used to assess differences in clinical characteristics, ARG counts, resistome diversity and ARG richness, pre- and post-FMT. All 13 of the patients with sufficient stool samples for analysis had recently received antibiotics for pouchitis prior to a single endoscopic FMT. Fecal microbiomes of all patients had evidence of multi-drug resistance genes and ESBL resistance genes at baseline; 62% encoded fluoroquinolone resistance genes. A numerical decrease in overall ARG counts was noted post-FMT, but no statistically significant differences were noted (P = 0.19). Richness and diversity were not significantly altered. Three patients developed infections during the 5-year follow-up period, none of which were associated with MDRO. Antibiotic resistance genes are prevalent among antibiotic-exposed patients with chronic pouchitis. FMT led to a numerical decrease, but no statistically significant change in ARG, nor were there significant changes in the diversity, richness, or evenness of ARGs. Further investigations to improve FMT engraftment and to optimize FMT delivery in patients with inflammatory pouch disorders are warranted.

Serratia Infections in Burn Care.

Serratia marcescens is an opportunistic nosocomial pathogen with significant implications for burn care due to its multidrug resistance, virulence, and ability to colonize hospital environments. This retrospective study, conducted at an American Burn Association Verified Burn Centre, reviewed 22 cases of S. marcescens infections from 2015 to 2020. Patients exhibited a mean total body surface area (TBSA) burned of 28% (range: 2-71%), with 68% sustaining burns >20% TBSA and 40.9% presenting with inhalation injuries. The pathogen was most commonly isolated from sputum (36%) and burn wound tissue (50%), with a mean time to positive culture of 8.7 days. Early-onset infections were associated with increased mortality, particularly in patients with major burns, as five out of seven such individuals succumbed to infection. The overall mortality rate was 23%, despite timely antibiotic administration. Targeted topical antimicrobials, such as Dakin's solution, nanocrystalline silver, and polyhexamethylene biguanide (PHMB), offer potential benefits but lack robust evidence for optimal use. Stronger clinical data are needed to guide their application and improve outcomes. These findings underscore the need for enhanced surveillance, refined treatment strategies, and research into S. marcescens management in burn care.

Structural insights into binding-site access and ligand recognition by human ABCB1.

ABCB1 is a broad-spectrum efflux pump central to cellular drug handling and multidrug resistance in humans. However, how it is able to recognize and transport a wide range of diverse substrates remains poorly understood. Here we present cryo-EM structures of lipid-embedded human ABCB1 in conformationally distinct apo-, substrate-bound, inhibitor-bound, and nucleotide-trapped states at 3.4-3.9 Å resolution, in the absence of stabilizing antibodies or mutations. The substrate-binding site is located within one half of the molecule and, in the apo state, is obstructed by the transmembrane helix (TM) 4. Substrate and inhibitor binding are distinguished by major TM rearrangements and their ligand binding chemistry, with TM4 playing a central role in all conformational transitions. Furthermore, our data identify secondary structure-breaking residues that impart localized TM flexibility and asymmetry between the two transmembrane domains. The resulting structural changes and lipid interactions that are induced by substrate and inhibitor binding can predict substrate-binding profiles and may direct ABCB1 inhibitor design.

Loop-mediated isothermal amplification assay coupled with lateral flow dipstick for the rapid detection of methicillin-resistant Staphylococcus pseudintermedius from dogs.

Staphylococcus pseudintermedius is a global animal pathogen. Traditional identification methods are time-consuming necessitating a more efficient approach. This study validated and enhanced the loop-mediated isothermal amplification (LAMP) technique by integration it with a lateral flow dipstick (LFD) assay for the detection of S. pseudintermedius and methicillin-resistant S. pseudintermedius (MRSP) strains. Conventional identification methods were compared with LAMP and matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). The isolates were tested for MRSP detection using oxacillin and cefoxitin disk diffusion tests alongside the LAMP assay targeting the mecA gene, a marker for methicillin resistance. Results showed that LAMP combined with LFD effectively detected S. pseudintermedius and MRSP. This study identified 53 isolates as S. pseudintermedius by conventional and LAMP methods, with MALDI-TOF MS correctly identifying 39.62% (21/53). The mecA gene, crucial for methicillin resistance, was detected in all PCR-positive isolates (n = 33) by LAMP, while the disk diffusion method identified 69.70% (23/33) of mecA-positive strains. LAMP and conventional methods exhibited superior accuracy, sensitivity, and specificity (all 100%) compared to MALDI-TOF MS, which showed lower sensitivity (39.62%) for S. pseudintermedius identification. Similarly, the LAMP assay demonstrated higher accuracy, sensitivity, and specificity (all 100%) for MRSP detection compared to the disk diffusion method (83.33%, 69.70%, and 94.87%, respectively). The LAMP assay coupled with the LFD method proved suitable for routine bacterial identification in laboratories, offering adequate sensitivity and specificity with simple steps and short reaction time.

Anti-Biofilm Agents to Overcome Pseudomonas aeruginosa Antibiotic Resistance.

Pseudomonas aeruginosa is one of world's most threatening bacteria. In addition to the emerging prevalence of multi-drug resistant (MDR) strains, the bacterium also possesses a wide variety of virulence traits that worsen the course of the infections. Particularly, its ability to form biofilms that protect colonies from antimicrobial agents is a major cause of chronic and hard-to-treat infections in immune-compromised patients. This protective barrier also ensures cell growth on abiotic surfaces and thus enables bacterial survival on medical devices. Hence, as the WHO alerted to the need to develop new treatments, the use of anti-biofilm agents (ABAs) appeared as a promising approach. Given the selection pressure imposed by conventional antibiotics, a new therapeutic strategy has emerged that aims at reducing bacterial virulence without inhibiting cell growth. So-called anti-virulence agents (AVAs) would then restore the efficacy of conventional antibiotics (ATBs) or potentiate the effectiveness of the immune system. The last decade has seen the development of ABAs as AVAs against P. aeruginosa. This review aims to highlight the design strategy and critical features of these molecules to pave the way for further discoveries of highly potent compounds.

Determination of Staphylococcus aureus isolation, identification and antibiotic susceptibility in raw milk

Staphylococcus aureus in raw milk poses a potential risk to public health due to its toxin-producing strains and high levels of antibiotic resistance. In this study, the presence of S. aureus in raw milk and the antibiotic resistance profiles of the isolated strains were examined. A total of 100 raw milk samples were analyzed, and S. aureus contamination was detected in 47 samples at various levels. The contamination levels ranged from 2.00 to 4.99 log cfu/ml and 45.9% of the contaminated samples were found to be in 3-4 log cfu/ml range. The minimum inhibitory concentration values for the antibiotics cefoxitin, methicillin, tetracycline, tylosin, florphenicol, neomycin, ciprofloxacin, lincomycin, and polymyxin B were determined using the broth microdilution method to examine the antibiotic resistance profiles of the isolated strains. It was determined that 13 (27.6%) of the S. aureus isolates were resistant to all the tested antibiotic groups. Additionally, all isolates were resistant to cefoxitin, methicillin, tylosin, and lincomycin, followed by resistance rates of 95.8% to florphenicol, 89.4% to neomycin, and 87.3% to polymyxin B. Furthermore, all isolates were observed to be multidrug-resistant (MDR). This study indicates that the contamination of raw milk with S. aureus and the antibiotic resistance profile pose a significant public health risk. The fact that all isolates were MDR limits treatment options and complicates infection control. These findings show that the need for stricter hygiene practices in milk production processes and careful management of antibiotic use.

Combating Antibiotic-Resistant Bacterial Infection Using Coassembled Dimeric Antimicrobial Peptide-Based Nanofibers.

The emergence of multidrug-resistant (MDR) pathogens, coupled with the limited effectiveness of existing antibiotics in eradicating biofilms, presents a significant threat to global health care. This critical situation underscores the urgent need for the discovery and development of antimicrobial agents. Recently, peptide-derived antimicrobial nanomaterials have shown promise in combating such infections. Amino acid noncovalent forces, notably π-π stacking and electrostatic interactions, remain underutilized for guiding the coassembly of peptides into bacteriostatic nanomaterials. Thus, we constructed a dimeric nanopeptide system using the disulfide bonds of cysteine. The self-assembly of dimeric peptides into nanofibers was realized by the interaction of π-π aromatic amino acids (Trp, Phe, and Pyr) and the electrostatic attraction between oppositely charged amino acids (Asp and Arg). The optimal dimeric peptide 2D2W exhibits potent antibacterial activity against resistant bacteria and is nontoxic. Mechanistically, 2D2W penetrated the outer membrane after electrostatic adsorption, resulting in plasma membrane depolarization, homeostatic disruption, and ultimately bacterial death. In a mouse model of peritonitis, 2D2W demonstrated efficacy in the in vivo treatment of bacterial infections. In conclusion, the design of dimeric nanopeptides co-driven by intermolecular forces provides a promising avenue for the development of high-performance antimicrobial nanomaterials. These advances may also facilitate the application and advancement of peptide-based bacteriostatic agents in clinical practice.

Nutrient evaluation, minerals quantification and antibacterial potential of <i>Mentha longifolia</i> (L.) flower, leaves and stem against foodborne bacterial pathogens

This study was conducted for the assessment of the nutrition, minerals and antibacterial activities of leaves, stem and flower of Mentha longifolia (wild mint). Proximate compositions were carried out using standards methods, mineral analysis were determined using Atomic Absorption Spectrophotometer and Flame Photometer, antibacterial activities were assessed using Zone of Inhibition Assay. Broth dilution method was used to determine the Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The proximate composition of Mentha longifolia observed that moisture was found in the range of 2.3-2.8%, ash was 2.5-7.5%, crude fat was 0.5-2.1%, crude fiber was 8.5-22.5%, protein was 2.1-4.5%, carbohydrate was 69.6-78.7% and energy was 291.3-347.7 Kcal/100 g dw. Sodium concentration was found in the range of 1250-1590 mg/kg, Potassium was 3240-4820 mg/kg, Calcium was 12400-24000 mg/kg, Magnesium was 4800-9600 mg/kg, Zinc was 32-64 mg/kg, Iron was 140-498 mg/kg, Manganese was 32-107 mg/kg and Chromium was 3-6 mg/kg in Mentha longifolia leaves, flower and stem. The highest zone of inhibition (23±0.2) of Mentha longifolia leaves extract (tincture) was calculated against Bacillus cereus. Similarly the highest zone of inhibition of Mentha longifolia flower and stem was noted against Bacillus cereus in tincture extract were 17±01 mm and 16±01 mm respectively. The Mentha longifolia leaves MIC range was 40–120 mg/mL and MBC 60–200 mg/mL. The flower extracts MIC range 70–220 mg/mL and MBC 110–300 mg/mL. Generally the antibacterial activities of wild mint leaves extracts were higher as compared to flower and stem extracts (p<0.05). The results commonly observed Gram-negative bacteria are typically high opposed to the Mentha longifolia extracts as compared to Gram-positive bacteria. The proximate and minerals analysis concludes that this herb is used to formulate nutraceutical products and their extracts can be used against multi drug resistance bacteria accomplished of causing foodborne diseases.

Moxifloxacin-Loaded Polymeric Nanoparticles for Overcoming Multidrug Resistance in Chronic Pulmonary Infections Caused by Pseudomonas aeruginosa.

Pseudomonas aeruginosa (P. aeruginosa) infections are increasingly challenging due to their propensity to form biofilms and low outer membrane permeability, especially in chronically infected patients with thick mucus. P. aeruginosa exhibits multiple drug resistance mechanisms, making it one of the most significant global public health threats. In this study, we found that moxifloxacin (MXC) and antibacterial peptides (ε-poly-l-lysine, ε-PLL) exhibited a synergistic effect against multidrug-resistant P. aeruginosa (MDR-P. aeruginosa). MXC was combined with ε-PLL to prepare lipase-responsive nanoparticles (MCIP/(PEG-PCL)/PLL NPs) with a weakly negative charge. The weakly negatively charged MCIP/(PEG-PCL)/PLL NPs demonstrated remarkable mucus and biofilm penetration capabilities, thereby overcoming one of the adaptive drug resistance mechanisms. MCIP/(PEG-PCL)/PLL NPs improved the outer and inner membrane permeability and inhibited the expression of the efflux pump MexAB-OprM gene in MDR-P. aeruginosa, thereby overcoming mechanisms of both intrinsic and acquired drug resistance. Meanwhile, the nanoparticles demonstrated an ability to reduce repeated infections with MDR-P. aeruginosa. Additionally, the bacterial burden in the lungs of mice treated with MCIP/(PEG-PCL)/PLL NPs was significantly lower than that in the MXC group, resulting in a 99% clearance rate. Notably, MCIP/(PEG-PCL)/PLL NPs showed no toxicity toward BEAS-2B cells or RAW 267.4 cells, nor did they adversely affect pulmonary function or major organs. This study demonstrated the potential of the nanodrug delivery system composed of the antibiotic moxifloxacin and the antibacterial peptide ε-PLL in addressing the clinical challenges of treating chronic pulmonary infections caused by MDR-P. aeruginosa.