The global emergence of multidrug resistance (MDR) in gram-negative bacteria has become a matter of worldwide concern. MDR in these pathogens is closely linked to the overexpression of certain efflux pumps, particularly the resistance-nodulation-cell division (RND) efflux pumps. Inhibition of these pumps presents an attractive and promising strategy to combat antibiotic resistance, as the efflux pump inhibitors can effectively restore the potency of existing antibiotics. AcrAB-TolC is one well-studied RND efflux pump, which transports a variety of substrates, therefore providing resistance to a broad spectrum of antibiotics. To develop effective pump inhibitors, a comprehensive understanding of the structural aspect of the AcrAB-TolC efflux pump is imperative. Previous studies on this pump\'s structure have been limited to individual components or in vitro determination of fully assembled pumps. Recent advancements in cellular cryo-electron tomography (cryo-ET) have provided novel insights into this pump\'s assembly and functional mechanism within its native cell membrane environment. Here, we present a summary of the structural data regarding the AcrAB-TolC efflux pump, shedding light on its assembly pathway and operational mechanism.

Chemotherapy is still the main therapeutic strategy for gastric cancer (GC). However, most patients eventually acquire multidrug resistance (MDR). Hyperactivation of the EGFR signaling pathway contributes to MDR by promoting cancer cell proliferation and inhibiting apoptosis. We previously identified the secreted protein CGA as a novel ligand of EGFR and revealed a CGA/EGFR/GATA2 positive feedback circuit that confers MDR in GC. Herein, we outline a microRNA-based treatment approach for MDR reversal that targets both CGA and GATA2. We observed increased expression of CGA and GATA2 and increased activation of EGFR in GC samples. Bioinformatic analysis revealed that miR-107 could simultaneously target CGA and GATA2, and the low expression of miR-107 was correlated with poor prognosis in GC patients. The direct interactions between miR-107 and CGA or GATA2 were validated by luciferase reporter assays and western blot analysis. Overexpression of miR-107 in MDR GC cells increased their susceptibility to chemotherapeutic agents, including fluorouracil, adriamycin and vincristine, in vitro. Notably, intratumor injection of the miR-107 prodrug enhanced MDR xenograft sensitivity to chemotherapies in vivo. Molecularly, targeting CGA and GATA2 with miR-107 inhibited EGFR downstream signaling, as evidenced by the reduced phosphorylation of ERK and AKT. These results suggest that miR-107 may contribute to the development of a promising therapeutic approach for the treatment of MDR in GC.

Pseudomonas aeruginosa is one of the most common nosocomial pathogens and part of the top emergent species associated with antimicrobial resistance that has become one of the greatest threat to public health in the twenty-first century. This bacterium is provided with a wide set of virulence factors that contribute to pathogenesis in acute and chronic infections. This review aims to summarize the impact of multidrug resistance on the virulence and fitness of P. aeruginosa. Although it is generally assumed that acquisition of resistant determinants is associated with a fitness cost, several studies support that resistance mutations may not be associated with a decrease in virulence and/or that certain compensatory mutations may allow multidrug resistance strains to recover their initial fitness. We discuss the interplay between resistance profiles and virulence from a microbiological perspective but also the clinical consequences in outcomes and the economic impact.

UNASSIGNED: This study was aimed to investigate the multidrug resistance patterns in clinical isolates of Escherichia coli and their correlation with integrons and phylogenetic groupings.
UNASSIGNED: A total of 37 clinical E. coli isolates were evaluated for drug resistance patterns by disk diffusion method. Phylogenetic groupings and the presence of integrons among E. coli were determined by multiplex PCR assays.
UNASSIGNED: Multidrug resistance was identified in 84% of the clinical isolates of E. coli with higher resistance found against cephalosporins (94.6%) and fluoroquinolones (83.8%), while lower resistance was observed against polymyxins (24.3%) and carbapenems (29.7%). Metallo-β-lactamases were found in all carbapenem resistant isolates. The phylogenetic group B2 was the most dominant (40.5%), followed by groups A (35.1%), D (13.5%) and B1 (10.8%). Integrons were detected in 25 (67.6%) isolates and intI1, intI2, and intI3 genes were found in 62.2%, 18.9% and 10.8% of isolates respectively.
UNASSIGNED: Our results show that phylogenetic classification of E. coli is not relevant with antimicrobial resistance. However, there was strong association between the integron classes and resistance against β-lactam and fluoroquinolones antimicrobials. Additionally, this study highlighted that the presence of integrons plays a crucial role in the development of multidrug resistance in clinical isolates of E. coli. Most significantly, this is the first report of detection of three classes of integron among clinical isolates of E. coli in Pakistan.

BACKGROUND: The global burden associated with antimicrobial resistance is of increasing concern. The aim of this study was to evaluate risk factors associated with multidrug-resistant (MDR) infection and its clinical impact in a cohort of patients with healthcare-associated (HCA) bacteremic urinary tract infections (BUTI).
METHODS: This is a post-hoc analysis a prospective multicenter study of patients with HCA-BUTI (ITUBRAS-2). The primary outcome was MDR profile. Secondary outcomes were clinical response (at 48-72h and at hospital discharge) and length of hospital stay from onset of BUTI. Logistic regression was used to evaluate variables associated with MDR profile and clinical response. Length of hospital stay was evaluated using multivariate median regression.
RESULTS: 443 episodes were included, of which 271 (61.17%) were classified as expressing an MDR profile. In univariate analysis, MDR profile was associated with E. coli episodes (OR 3.13, 95% CI 2.11-4.69, p<0.001) and the extensively drug-resistant (XDR) pattern with P. aeruginosa etiology (OR 7.84, 95% CI 2.37-25.95; p=0.001). MDR was independently associated with prior use of fluoroquinolones (aOR 2.43; 95% CI 1.25-4.69), cephalosporins (aOR 2.14; 95% CI 1.35-3.41) and imipenem or meropenem (aOR 2.08; 95% CI 1.03-4.20) but not with prior ertapenem. In terms of outcomes, MDR profile was not associated with lower frequency of clinical cure, but with longer hospital stay.
CONCLUSIONS: MDR profile was independently associated with prior use of fluoroquinolones, cephalosporins, imipenem and meropenem, but not with prior ertapenem. MDR-BUTI episodes were not associated with worse clinical cure, although was independently associated with longer duration of hospital stay.

BACKGROUND: Intravenous fosfomycin (IVFOF) is gaining interest in severe infections. Its use may be limited by adverse events (AEs). Little experience exists on IVFOF therapeutic drug monitoring (TDM) in real-life setting.
METHODS: Retrospective study of patients receiving IVFOF for > 48 h at Policlinico Hospital (Milan, Italy) from 01/01/2019 to 01/01/2023. AEs associated to IVFOF graded CTCAE ≥ II were considered. Demographic and clinical risk factors for IVFOF-related AEs were analysed with simple and multivariable regression models. The determination of IVFOF TDM was made by a rapid ultraperformance liquid chromatography mass spectrometry method (LC-MS/MS) on plasma samples. The performance of TDM (trough levels (Cmin) in intermittent infusion, steady state levels (Css) in continuous infusion) in predicting AEs ≤ 5 days after its assessment was evaluated.
RESULTS: Two hundred and twenty-four patients were included. At IVFOF initiation, 81/224 (36.2%) patients were in ICU and 35/224 (15.7%) had septic shock. The most frequent infection site was the low respiratory tract (124/224, 55.4%). Ninety-five patients (42.4%) experienced ≥ 1AEs, with median time of 4.0 (2.0-7.0) days from IVFOF initiation. Hypernatremia was the most frequent AE (53/224, 23.7%). Therapy discontinuation due to AEs occurred in 38/224 (17.0%). ICU setting, low respiratory tract infections and septic shock resulted associated with AEs (RRadjusted 1.59 (95%CI:1.09-2.31), 1.46 (95%CI:1.03-2.07) and 1.73 (95%CI:1.27-2.37), respectively), while IVFOF daily dose did not. Of the 68 patients undergone IVFOF TDM, TDM values predicted overall AEs and hypernatremia with AUROC of 0.65 (95%CI:0.44-0.86) and 0.91 (95%CI:0.79-1.0) respectively for Cmin, 0.67 (95%CI:0.39-0.95) and 0.76 (95%CI:0.52-1.0) respectively for Css.
CONCLUSIONS: We provided real world data on the use of IVFOF-based regimens and associated AEs. IVFOF TDM deserves further research as it may represent a valid tool to predict AEs.
CONCLUSIONS: Real world data on intravenous fosfomycin for severe bacterial infections. AEs occurred in over 40% (therapy discontinuation in 17%) and were related to baseline clinical severity but not to fosfomycin dose. TDM showed promising results in predicting AEs.

OBJECTIVE: Escherichia coli is one of the most common bacteria isolated from urine samples collected from dogs and cats with urinary tract infection (UTI). Uncomplicated UTIs in dogs and cats can be treated with short courses of first-line antimicrobial drugs, e.g. amoxicillin, amoxicillin with clavulanic acid, or trimethoprim/sulfonamide. Recurrent or complicated UTIs often require long-term treatment with broad-spectrum antibiotics. However, the choice of drug should be based on antimicrobial susceptibility.
METHODS: Between March - September 2022, E. coli isolates cultured from the urine of 66 dogs and 41 cats with UTI symptoms were tested for antimicrobial resistance by using Minimum Inhibitory Concentration (MIC). Antimicrobial susceptibility was tested for ampicillin, ampicillin/sulbactam, cefazolin, cefuroxime, aztreonam, gentamycin, amikacin, colistin, trimethoprim/sulfamethoxazole, ciprofloxacin, chloramphenicol and tetracycline.
RESULTS: The highest prevalence of resistance was documented for ampicillin (68% in dogs, 100% in cats) and ampicillin with sulbactam (59% in dogs, 54% in cats). The most common antimicrobial resistance patterns of E. coli were ampicillin alone (12 isolates, 29.3% in cats) and beta-lactams, including aztreonam (14 isolates, 21.2% in dogs).
CONCLUSIONS: High resistance to aztreonam (61% and 32% of isolates from dogs and cats, respectively), other beta-lactams, and fluoroquinolones should cause be alarm due to zoonotic potential and cross-transmission of antimicrobial-resistant microorganisms between animals and humans.

UNASSIGNED: Neuropathic adverse events occur frequently in linezolid-containing regimens, some of which remain irreversible after drug discontinuation.
UNASSIGNED: We aimed to identify and validate a host RNA-based biomarker that can predict linezolid-associated neuropathy before multidrug-resistant/rifampicin-resistant tuberculosis (MDR/RR-TB) treatment initiation and to identify genes and pathways that are associated with linezolid-associated neuropathy.
UNASSIGNED: Adult patients initiating MDR/RR-TB treatment including linezolid were prospectively enrolled in 3 independent cohorts in Germany. Clinical data and whole blood RNA for transcriptomic analysis were collected. The primary outcome was linezolid-associated optic and/or peripheral neuropathy. A random forest algorithm was used for biomarker identification. The biomarker was validated in an additional fourth cohort of patients with MDR/RR-TB from Romania.
UNASSIGNED: A total of 52 patients from the 3 identification cohorts received linezolid treatment. Of those, 24 (46.2%) developed peripheral and/or optic neuropathies during linezolid treatment. The majority (59.3%) of the episodes were of moderate (grade 2) severity. In total, the expression of 1,479 genes differed significantly at baseline of treatment. Suprabasin (SBSN) was identified as a potential biomarker to predict linezolid-associated neuropathy. In the validation cohort, 10 of 42 (23.8%) patients developed grade ≥3 neuropathies. The area under the curve for the biomarker algorithm prediction of grade ≥3 neuropathies was 0.63 (poor; 95% confidence interval: 0.42 - 0.84).
UNASSIGNED: We identified and preliminarily validated a potential clinical biomarker to predict linezolid-associated neuropathies before the initiation of MDR/RR-TB therapy. Larger studies of the SBSN biomarker in more diverse populations are warranted.

This study aimed to isolate and characterize biological and genomic features of a phage infecting Enterococcus faecalis. The phage was isolated from environmental water and temperature and pH stability, one-step growth curve, and multiplicity of infection (MOI) were determined. Whole genome sequencing (WGS) and structural and functional annotations were performed. Its antibiofilm activity was also evaluated. The optimal MOI was 0.01, the latency period was 5 min, and the burst size was 202 plaque forming unit (PFU). High phage survival rates were observed at between pH 4-10 and temperatures between 4-50 °C. WGS and Transmission electron microscopy (TEM) showed that it was an Efquatrovirus representing siphovirus morphotype respectively. It was named as Enterococcus phage Ef212 and has a linear 40,690 bp double-stranded DNA with 45.3% G + C content (GenBank accession number: OR052631). BACPHLIP tool demonstrated that Enterococcus phage Ef212 is a lytic phage (88%). A total of 80 open reading frames (ORFs) were found and there were no antibiotic resistance genes, pathogenicity, virulence genes, or tRNAs in the phage genome. It was diverged from the most similar phages (identity, 88.35%; coverage, 89%) by phylogenetic analysis. Phage Ef212 shared a large part of its genome (60/80) with several other phages, yet some unique parts were found in their genomes. Host range analysis showed that phage Ef212 showed lytic activity against vancomycin-resistant and vancomycin-susceptible E. faecalis clinical isolates. This novel phage Ef212 showed the ability to inhibit and reduce the biofilm formation by around 42% and 38%, respectively. The biological and genomic features indicate that having an effective antibacterial activity, phage Ef212 seemed a promising therapeutic and biocontrol agent.

UNASSIGNED: Antimicrobial resistance is increasingly becoming a global health concern. This study aimed to investigate and report MDR Escherichia coli (E. coli) prevalence, resistance, and virulence genes from poultry in Jos, Plateau State, Nigeria.
UNASSIGNED: The samples were analyzed using microbiological standard methods and polymerase chain reactions (PCRs).
UNASSIGNED: A total of 179 cloacal swabs were collected from bothlocal and exotic poultry breeds, of which 99.4% (178/179) tested positive for E. coli. Among these culturally identified samples, 99.4% (177/178) were furtherconfirmed Escherichia coli with a molecular weight of 401 bp. Multidrugresistance of 45% (80/178) was observed from the confirmed isolates. PCR assays were conducted to detect genes associated with resistance to antibiotics, specifically, tetracycline (tetA gene), sulfonamide (sul1 gene), ampicillin (ampC gene), and quinolone (gyrA gene). Antimicrobial susceptibility test (AST) results revealed substantial antibiotic resistance, with 81.9% (145/177) of the isolates being resistant to tetracycline, 80.2% (142/177) to quinolone, 69.5% (123/177) to sulfonamide, and 66.1% (117/177) to ampicillin. Further analysis on 18 isolates that showed resistance to up to four different antibiotics was carried out using multiplex PCR to detect eae, hlyA, rfbE, fliC, and fstx virulence genes. The study found that 44.4% (15/18) of the isolates were positive for the eae gene, 27.7% (5/18) for stx, 22.2% (4/18) for rfbe gene, and 5.5% (1) for hlya gene, and none tested positive for fliC gene.
UNASSIGNED: These results showed high antibiotic resistance, virulent genes, and significant levels of MDR in E. coli from poultry. This study highlights the urgent need for antimicrobial stewardship practices within the poultry industry due to their profound implications for food safety and public health. This issue is particularly critical in Nigeria, where poultry farming constitutes a significant portion of smallholder farming practices.