Multidrug Resistant Gram Research Articles

Multidrug Resistance Gram-negative Bacteria in Intensive Care Unit of Tertiary Care Hospital: A Descriptive Cross-sectional Study

Introduction: Antimicrobial resistance is global health problem, amongst major causes for mortality. It is one of the hinderance for achievement of Sustainable Goal 3 (Good health and well-being) of WHO. Multidrug resistant gram negative bacteria are major threat to humanity especially patients admitted in intensive care unit. This is associated with to treatment failure and mortality of the patients in intensive care unit. Therefore, this study was conducted to find out the prevalence of Multidrug resistant gram negative bacteria in intensive care unit of tertiary care center. Methods: A descriptive cross-sectional study was conducted in the Department of Microbiology of a tertiary care hospital from February, 2020 till August, 2021 for 18 months after obtaining ethical approval from the Institutional Review Committee (Reference Number: 246). All the samples from Intensive Care Unit were processed following standard methodology. Only Gram-negative bacteria isolated from samples were included in the study. Convenience sampling method was used. The point estimated was calculated at 95% Confidence Interval. Data was entered in Microsoft Excel 2016 and analysis was done using IBM SPSS Statistics version 16.0.Results: Out of 500 samples only 380 showed growth of gram negative bacteria. The prevalence Multi Drug Resistance was 83.15%. The prevalence of multidrug resistant was notably higher among Acinetobacter spp (100%) followed by Non fermenter (95%) and Escherichia coli (87.1%). Multidrug resistant isolates were least resistant towards carbapenem group of antibiotics.Conclusions: The prevalence of Multidrug resistant gram negative bacteria was found to be lower than in the study conducted in similar setting.

Antibacterial and Wound Healing Assessment of Silver Nanoparticles against Multidrug-Resistant Klebsiella variicola

The increase in antimicrobial resistance and the absence of novel antibiotic development cause problems in controlling infections for wound healing. Antibacterial properties of nanomaterials have emerged as a potentially effective approach in the pursuit of superior alternatives, nevertheless, the toxicity associated with higher concentrations has emerged as a significant obstacle. According to this study, green nanoparticle synthesis is demonstrated to be both economical and biocompatible on account of the bioactive compounds present. In the present work, silver nanoparticles prepared by using Pistacia khinjuk gum, then, nanoparticle-based cream was prepared and compared with Fusidin and Vaseline creams via assessment in vitro antibacterial and in vivo wound healing activity on Wistar albino rats infected with multi drug resistant Gram negative bacteria which was newly recorded in Iraq, namely Klebsiella variicola. The findings revealed that the application of nanoparticle cream resulted in more rapid and effective wound healing (11 days), demonstrating a significant synergistic effect in comparison to Fusidin (16 days), Vaseline (20 days), and the untreated control group rats (32 days). The results indicated that green nanoparticles proved to be a significant strategy in the fight against multidrug resistant bacteria, without any toxicity concerns.

Ventilator Associated Pneumonia in Tertiary Care Hospital, Maharajgunj, Kathmandu, Nepal

Introduction: Ventilator Associated Pneumonia (VAP) is the most common nosocomial infection among intensive care unit (ICU) patients and lack of much information in Nepal. So, the aim of this study was to determine prevalence and bacteriological profile of VAP with special reference to multi-drug resistant (MDR), Methicillin-resistant Staphylococcus aureus(MRSA), Metallo-β-Lactamase(MBL), Extended-Spectrum β-Lactamase(ESBL)-producing bacterial strains. Methods: A total 150 tracheal specimens were studied during June 2011 to May 2012 at Department of Microbiology, TUTH as described by American Society for Microbiology (ASM). Combination disk method was done for the detection of ESBL and MBL producing isolates. Results: Prevalence of VAP was found to be 34%. Acinetobactereal coaccticusbaumannii complex (44%) was the commonest isolate, followed by Klebsiellapneumoniae (22%), Pseudomonas aeruginosa (16%) and Staphylococcus aureus (12%). Among MDR Gram negative bacteria (GNB), 39% were MBL and 33% were ESBL-producers. All GNB (61) were sensitive to Polymyxin B and Colistinsulphate, whereas, 48% were found resistant to Carbapenems. Prevalence of MRSA was 75%, which were all sensitive to Vancomycin. Conclusion: High prevalence of VAP, MDR along with MRSA or ESBL or MBL producing strains was found in the study. Thus, suitable control measures must be adopted to cope up this alarming situation with genetic characterization.

Frequency and MIC-based Antimicrobial Resistance Profile of MDR and XDR Gram Negative Isolates of Blood Culture Specimens in a Tertiary Care Setting

The escalation of antimicrobial resistance (AMR) among Gram-negative bacteria, particularly multidrug-resistant (MDR) and extensively drug-resistant (XDR) pathogens, posed a significant challenge in tertiary care settings. This paper comprehensively analyzed the antimicrobial resistance profile of MDR and XDR Gram-negative isolates from blood culture specimens at Jinnah Hospital, Lahore, a leading tertiary care facility. Over a period of one year, 9600 blood culture specimens were processed, revealing a high incidence of resistance to a wide array of antibiotics, with notable findings including 100% susceptibility to Colistin and over 90% resistance to several commonly used antibiotics such as Ciprofloxacin and Piperacillin/Tazobactam. Among the positive isolates, 33.8% were classified as MDR and 66.2% as XDR. The study emphasized the critical role of Minimum Inhibitory Concentrations (MICs) in guiding therapeutic decisions, highlighting the wide variability in resistance patterns and the necessity for personalized antimicrobial therapy. The prevalence of MDR and XDR isolates underscored the urgent need for advanced treatment modalities, comprehensive surveillance, and robust antimicrobial stewardship initiatives. Additionally, the study pointed to the emergence of colistin resistance as a critical challenge in managing infections caused by these pathogens. Through detailed analysis and discussion, this study illuminated the grave challenge posed by AMR in tertiary care settings. It emphasized the importance of innovative approaches to antimicrobial stewardship, developing new antimicrobial agents, and ongoing surveillance to effectively combat this public health crisis.

Risk Factors and Outcomes of Candida auris in Southeast Michigan

Background: Candida auris is an emerging multidrug resistant fungus that presents a serious global health threat and causes severe infections with a high mortality rate in hospitalized patients with significant underlying comorbidities. We describe the risk factors and clinical outcomes associated with C. auris in Southeast Michigan. Methods: This is a retrospective case series of culture-positive C. auris patients who had contact with our healthcare facility in Detroit from 2021 to 2023. We evaluated demographics, comorbidities, risk factors, and outcomes. A comparative analysis of colonized and infected patients was performed. Results: Forty-eight (81%) colonized and 11 (19%) infected patients were included (Table); 70% were male with median age of 66 years. All variables were comparable between the two groups except chronic kidney disease, which was significantly more prevalent among colonized patients (40% vs 0, p=0.011). All patients had prior exposure to acute care hospital (ACH), 37% to long-term acute care hospital, and 42% to skilled nursing facility within 1 year of diagnosis. Chronic wounds, prior broad-spectrum antibiotic use, and indwelling devices were prevalent in both groups; more than half required mechanical ventilation in the last month, and one third had tracheostomy at the time of C. auris detection. Almost 60% had a prior history of drug-resistant organisms, including multi-drug resistant gram negative (37%) and carbapenem-resistant (20%) organisms. Blood (82%) and wound (18%) were sources of invasive candidiasis. More than half (61%) of the testing was performed at ACH. Nine patients (82%) with invasive disease were treated with echinocandins (88%); among the colonized, two (4%) were treated with echinocandins but had persistent colonization. Thirty-day mortality was not significantly different among the two groups and was nearly 20%. Conclusions: In this large cohort study, a history of healthcare exposure, drug-resistant organisms, use of broad-spectrum antibiotics, indwelling devices, and chronic wounds were common risk factors among C. auris patients. Limiting the use of broad-spectrum antimicrobials and invasive devices, adherence to infection prevention and control practices, and interfacility transfer communication are important mitigating strategies to reduce the incidence and spread of C. auris.

Molecular Identification of Some Multidrug Resistance Gram Negatives Bacteria from Clinical Mastitis Cow and Study the Antimicrobial Activity of Thymus Vulgaris in Basrah Provence

Molecular Identification of Some Multidrug Resistance Gram Negatives Bacteria from Clinical Mastitis Cow and Study the Antimicrobial Activity of Thymus Vulgaris in Basrah Provence

Epidemiology, Clinical Conditions, Pathogenesis and Mechanism of Resistant of Acinetobacter baumannii: A Narrative Review

The world is facing a growing threat from multidrug-resistant (MDR) gram negative “superbugs,” such as Acinetobacter baumannii. This morbidity and mortality loss caused there of indirectly hampers the economic developments in countries. These multidrug-resistant A. baumannii worldwide represents a major public health problem. The development of antibiotics decreased the mortality among the human and animals leading to a better life expectancy. But the injudicious use of antimicrobials and selection pressure the microbes have developed resistance which became more prominent during last few decades. High antimicrobial resistance was observed against all β-lactam and non- β-lactam antibiotics by the MBL producers. In developing countries also, the misuse and underuse of antimicrobials due to lack of awareness of patients, medical workers and financial problems emerged the antimicrobial resistant strains. Due to rapid globalization of human population by travel and other factor these resistant strains spread easily between developed and developing countries making it a global problem. Bangladesh Journal of Medical Microbiology, July 2023;17 (2):88-92

Approach to multidrug resistant infections in pediatric transplant recipients.

There is increasing recognition of infections due to multidrug-resistant Gram negative (MDRGN) bacterial infections among children undergoing solid organ and hematopoietic cell transplantation, which may be associated with morbidity and mortality. We present two vignettes that highlight the clinical challenges of evaluation, management, and prevention of MDRGN bacterial infections in children prior to and after transplantation. The goal of this discussion is to provide a framework to help develop an approach to evaluation and management of these infections. Source control remains the utmost priority in management of MDR infections and is paired with antibiotic selection guided by in vitro susceptibilities, adverse effect profiles, and clinical response. Identification and confirmation of resistance can be challenging and often requires additional testing for recognition of complex mechanisms. Current antimicrobial approaches to MDRGN infections include use of novel agents, prolonged infusion, and/or combination therapy. We also discuss preventative efforts including infection control, antimicrobial stewardship, targeted pre-emptive or prophylactic treatment, and decolonization. The impact of MDRGN infections on patient and graft survival highlights the need to optimize treatment and prevention strategies.

730. Emerging patterns of multidrug resistance Gram negative bacterial infections and its clinical outcome at a tertiary medical center

Abstract Background Antimicrobial resistance (AMR) is a complex threat to global health security and universal health coverage. The continued escalation of AMR among Gram-negative bacteria (GNB) is a major concern due to the endemic presence of MDR and extremely drug-resistant (XDR) pathogens.In this regard, the present study aimed to asses the magnitude of MDR, its risk factors, and mortality in MDR/XDR - GNB. Methods GNB isolates were retrieved from patients, identified and assessed for antibiotic resistance pattern using VITEK® 2 compact system. The extended spectrum β-lactamase (ESBL) production in 100 GNB isolates was determined by double disk synergy test and genes confirmed by PCR in retrospective cohort study (2011-2012). The carbapenemase production in 100 isolates was confirmed by modified carbapenem inactivation method in prospective cross-sectional study (2021-2022). The metallo β-lactamase (MBLs) were screened by combined disk test and carbapenemase genes detected by multiplex-PCR. Minimum inhibitory concentration (MIC) of colistin was determined by Broth Micro dilution method and clonal relatedness was evaluated by Multilocus sequence typing (MLST). Results In retrospective study, all cases confirmed ESBL with high incidence of antibiotic resistance in cephalosporins,chloramphenicol and ciprofloxacin. All isolates were susceptible to carbapenem. bla TEM and bla CTX-M were prevalent ESBL genes, with 7 % mortality. In prospective study, isolates were positive for carbapenemase with XDR pattern and 47% of mortality. 90% isolates were MBLs positive and 30% had at least two carbapenemase genes, the combination of bla OXA-48 and bla NDM-1 was highly prevalent. Colistin resistance was observed in 20% and 30% isolates with 8 and 4 µg/ml MICs, respectively. Further, multiplex-PCR confirmed the mcr genes and clonal relatedness was determined. Conclusion The high prevalence rate of MDR-GNB from producing ESBLs (2011-12) to carbapenemase (2021-2022) was observed. Our results emphasize on antibiotic stewardship policies and regular surveillance programmes for monitoring AMR and screening of drug resistance genes. MLST, molecular surveillance, is valuable tool for rapid epidemiological investigation with precision in determining clonal relatedness Disclosures All Authors: No reported disclosures

Designing of fragment based inhibitors with improved activity against E. coli AmpC β-lactamase compared to the conventional antibiotics

One of the most common primary resistance mechanism of multi-drug resistant (MDR) Gram negative pathogenic bacteria to combat β-lactam antibiotics, such as penicillins, cephalosporins and carbapenems is the generation of β- lactamases. The uropathogenic E. coli is mostly getting multi-drug resistance due to the synthesis of AmpC β-lactamases and therefore new antibiotics and inhibitors are needed to treat the evolving infections. The current study was designed for targetting AmpC β-lactamase of E. coli using molecular docking based virtual screening, linking fragments for designing novel compounds and binding mode analysis using molecular dynamic simulation with target protein. The FCH group all-purpose fragment library consisting of 9388 fragments has been screened against AmpC β-lactamase protein of E. coli and the antibiotics and anti-infectives used in treatment of Urinary tract Infections (UTIs) were also screened with AmpC β-lactamase protein. Among the 9388 fragments, 339 fragment candidates were selected and linked with cefepime antibiotic having maximum binding affinity for AmpC target protein. Computational analysis of interactions as well as molecular dynamics (MD) simulations were also conducted for identifying the most promising ligand-pocket complexes from docking investigations to comprehend their thermodynamic properties and verify the docking outcomes as well. Overall, the linked complexes (LCs) showed good binding interactions with AmpC β-lactamase. Interestingly, our fragment-based LCs remained relatively stable in comparison with cefepime antibiotic. Moreover, S12 fragment linked complex remained the most stable during 50 ns with remarkable number of interactions indicating it as promising candidate in novel lead discovery against MDR E. coli infections.

Polymyxins leading to nephrotoxicity

Drug resistance gram-negative bacteria are the most hazardous type of germ because they cause life-threatening illnesses. Polymyxins are cyclic lipodecapeptide antibiotics that are effective against gram-negative bacteria like Acinetobacter, Pseudomonas, and other Enterobacteriaceae (such Klebsiella, Escherichia coli, and Serratia). Polymyxins kill bacteria by rupturing the bacterial outer membrane (OM). The main side effect of this antibiotic class is the development of kidney damage. Transposable genetic elements, such as MCR genes, can encode bacterial resistance to polymyxins. Colistin's prodrug is colistimethate sodium (CMS). Polymyxin dosage should be modified based on renal function. Polymyxins have demonstrated excellent clinical results, which have aided in the development of a better dosage regimen. Monte Carlo simulations were used to determine the most effective polymyxin dosages. Polymyxin resurgence has resulted in the eradication of multidrug resistant gram negative bacteria.

Phenotypic methods for detection of metallo-β-lactamase (MBL) production in multidrug resistant gram negative bacilli – comparative study

Introduction: One of the most common mechanism of resistance of bacterial pathogens to β-lactam antibiotics is production of β-lactamase, there are different types of Beta lactamases, which are expressed by drug resistant gram-negative bacteria. Carbapenemases (Metallo beta lactamases/MBL) are the β-lactamases with the widest spectrum of activity. Early detection of MBL-producing organisms is crucial to establish appropriate antimicrobial therapy and to prevent their interhospital and intrahospital dissemination. Several phenotypic methods are available for the detection of MBL producing bacteria. As there is no standardized method present study was done to screen MDR gram negative bacilli isolated from clinical samples for MBL-production by a low cost, convenient and sensitive procedure. Methods: All non-duplicate MDR gram negative isolates obtained from various clinical samples were screened for carbapenam resistance. All carbapenam resistant bacteria were screened for production of MBL by 3 phenotypic tests (Double disc synergy, combined disk test, Hodge test). The results were compared and analyzed on the basis of results obtained by E test. Results: During Study Period, 988 non duplicate gram negative bacilli were isolated, 70.64% (698) were multi drug resistant. Amongst Total number of MDR Isolates to carbapenam resistance was seen in 62(9.28%). These 62 isolates that were resistant to carbapenam were tested for MBL production. 54 (87%) of these 62 isolates showed MBL production by disc potentiation test whereas 41 isolates (66%) gave positive result by DDST. By Modified Hodge test, out of 62, 48 isolates (77.4%) were MBL positive. Compared to E- test, the Sensitivity Specificity and Accuracy for Disc potentiation test was 90%,100% and 90.32%, for Modified Hodge test was 80%,100% and 80.6% and for Double disc synergy test was 68.3%,100% and 69.3%. Conclusion: In our study, in comparison to MBL E test, disc potentiation test is more sensitive than double disc synergy test and Modified Hodge test for detection of MBL phenotypically

Efficacy of Ceragenins Alone and in Combinations with Antibiotics Against Multidrug-Resistant Gram Negative Pathogens from Bloodstream Infections.

Ceragenins (CSAs) that mimic the activities of antimicrobial peptides may be new options for the treatment of infections caused by multidrug-resistant pathogens. This study investigated the antibacterial activities of eight different ceragenins against MDR pathogens and the synergistic effects of some ceragenins in combinations with antibiotics (meropenem-MEM, ceftazidime + avibactam-CZA, tigecycline-TIG). A disc diffusion method was used for antibiotic susceptibility tests, a broth microdilution, and checkerboard methods were used to detect minimum inhibitory concentrations (MICs) and the effects of combinations, respectively. While MIC90 values CSA-13, CSA-44, CSA-131 against Klebsiella pneumoniae isolates had similar effect with MEM (8µg/ml); CSA-13, CSA-44, CSA-131, CSA-138, and CSA-144 had better activity than MEM against Acinetobacter baumannii and Pseudomonas aeruginosa isolates. In particular, CSA-44 and CSA-131 were effective against A. baumannii and P. aeruginosa isolates which resistant to both COL and MEM. CSA-44+MEM and CSA-131+CZA combinations showed synergistic activity against most (70%) of MDR- E. coli isolates. Although TIG is known to have weak activity in nonfermentative bacteria, CSA-44+TIG combination showed synergistic activity against two (17%) of the A. baumanni isolates. In addition, CSA-44+TIG and CSA-131+TIG combinations showed additive effects against all P. aeruginosa isolates. Antagonism was not detected in any of the combinations. CSA-44 and CSA-131 alone/or in combinations with MEM or CZA can be considered as new alternative treatments in serious infections caused by MDR pathogens.

Predictors and Outcomes of Multidrug-Resistant Gram-Negative Bacterial Bloodstream Infections in Pediatric Oncology Patients

Background Pediatric patients with cancer are at great risk of infection either from disease process or after being immuno-suppressed by chemotherapy and radiotherapy, this is especially with gram negative and multidrug resistant (MDR) pathogens. The primary aim of our study is to detect the frequency of multidrug resistant gram negative bacteria (MDR-GNB) infections at the Pediatric Oncology Department. The secondary aim is to identify the patterns of resistance of different pathogens to commonly used antimicrobials and detect the risk factors and outcomes of MDR-GNB infections in pediatric oncology patients. Patients and Methods We studied episodes of fever and /or bacteremia in children (aged 1 m to 18 y) with hematologic and solid malignancies in the pediatric oncology department in Ain Shams University Hospital between January 2020 and March 2021. We studied different risks for MDR-GNB including sex, age, underlying malignancy, the presence of indwelling catheter, absolute neutrophil count and other laboratory investigations. Results MDR bacteria were isolated in about 15% samples. The most commonly detected MDR-GNB pathogens were Klebsiella (61.1%) and Acintobacter (22.2%). Among studied patients, MDR-GNB were significantly reported among patients with T-lymphoblastic lymphoma (p = 0.006). Although most patients were neutropenic, neutrophil count was not significantly correlated (p = 0.981). Low serum albumin on the other hand was significantly correlated with MDR-GNB (p = 0.009). Conclusion MDR-GNB is a significant threat to pediatric oncology patients. Contact precautions for all patients with colonization or infection with MDR pathogens and an antimicrobial stewardship based on local epidemiology should be implemented to prevent MDR infections.

Serum Cystatin C as a Marker for Acute Kidney Injury Evaluation in Neonates Treated with Colistin

Background Colistin is increasingly used worldwide due to the emergence of multi-drug resistant (MDR) gram negative bacilli with concerns about its side effects especially nephrotoxicity. Serum cystatin C (CysC) is an endogenous protease inhibitor produced at a constant rate by nucleated cells and used as a filtration marker of glomerular filtration rate (GFR). Aim to study the effect of colistin on serum cystatin C as a marker for acute kidney injury in neonates in relation to serum urea and serum creatinine. Patients and method 78 neonates with gestational age of at least 30 weeks after treatment with colistin or antibiotics were divided into two groups non – colistin group and colistin group 39 pateints on each group. Kidney function tests were assessed before treatment and also after treatment but together with Kidney Disease Improving Global Outcome (KDIGO) criteria & serum cystatin C. Results Serum cystatin C was found to be significantly higher in colistin group than non – colistin group. No significant differences were found between both groups regarding serum creatinine, serum urea and even KDIGO criteria of acute kidney injury in neonates. Conclusion Serum cystatin C is an early marker of acute kidney injury in neonates which may not be detected by serum urea or serum creatinine

Morphological modification of silver nanoparticles against multi-drug resistant gram–negative bacteria and cytotoxicity effect in A549 lung cancer cells through in vitro approaches

Morphological modification of silver nanoparticles against multi-drug resistant gram–negative bacteria and cytotoxicity effect in A549 lung cancer cells through in vitro approaches

Use of Newer and Repurposed Antibiotics against Gram-Negative Bacteria in Neonates.

Antimicrobial resistance has become a significant public health problem globally with multidrug resistant Gram negative (MDR-GN) bacteria being the main representatives. The emergence of these pathogens in neonatal settings threatens the well-being of the vulnerable neonatal population given the dearth of safe and effective therapeutic options. Evidence from studies mainly in adults is now available for several novel antimicrobial compounds, such as new β-lactam/β-lactamase inhibitors (e.g., ceftazidime-avibactam, meropenem-vaborbactam, imipenem/cilastatin-relebactam), although old antibiotics such as colistin, tigecycline, and fosfomycin are also encompassed in the fight against MDR-GN infections that remain challenging. Data in the neonatal population are scarce, with few clinical trials enrolling neonates for the evaluation of the efficacy, safety, and dosing of new antibiotics, while the majority of old antibiotics are used off-label. In this article we review data about some novel and old antibiotics that are active against MDR-GN bacteria causing sepsis and are of interest to be used in the neonatal population.

New Antimicrobials for the Treatment of Neonatal Sepsis Caused by Multi-Drug-Resistant Bacteria: A Systematic Review.

Infections by multi-drug-resistant (MDR) organisms are sharply increasing in newborns worldwide. In low and middle-income countries, a disproportionate amount of neonatal sepsis caused by MDR Gram negatives was recently reported. Newborns with infections by MDR organisms with limited treatment options may benefit from novel antimicrobials. We performed a literature search investigating the use in newborns, infants and children of novel antimicrobials for the treatment of MDR Gram negatives, namely ceftazidime/avibactam, ceftolozane/tazobactam, cefiderocol, meropenem/vaborbactam, imipenem/relebactam, and Gram positives with resistance of concern, namely ceftaroline and dalbavancin. PubMed, EMBASE, and Web of Science were searched. A total of 50 records fulfilled the inclusion criteria. Most articles were case reports or case series, and ceftazidime/avibactam was the most studied agent. All studies showed favorable efficacy and safety profile in newborns and across different age cohorts. novel antibiotics may be considered in newborns for the treatment of MDR Gram negatives with limited treatment options and for Gram positives with resistance concerns. Further studies are needed to address their effectiveness and safety in newborns.

Snapshot of Phenotypic and Molecular Virulence and Resistance Profiles in Multidrug-Resistant Strains Isolated in a Tertiary Hospital in Romania.

A current major healthcare problem is represented by antibiotic resistance, mainly due to multidrug resistant (MDR) Gram negative bacilli (GNB), because of their extended spread both in hospital facilities and in the community's environment. The aim of this study was to investigate the virulence traits of Klebsiella pneumoniae, Acinetobacter baumannii, and Pseudomonas aeruginosa MDR, XDR, and PDR strains isolated from various hospitalized patients. These GNB strains were investigated for the presence of soluble virulence factors (VF), such as hemolysins, lecithinase, amylase, lipase, caseinase, gelatinase, and esculin hydrolysis, as well as for the presence of virulence genes encoding for VF involved in adherence (TC, fimH, and fimA), biofilm formation (algD, ecpRAB, mrkA, mrkD, ompA, and epsA), tissue destruction (plcH and plcN), and in toxin production (cnfI, hlyA, hlyD, and exo complex). All P. aeruginosa strains produced hemolysins; 90% produced lecithinase; and 80% harbored algD, plcH, and plcN genes. The esculin hydrolysis was detected in 96.1% of the K. pneumoniae strains, whereas 86% of them were positive for the mrkA gene. All of the A. baumannii strains produced lecithinase and 80% presented the ompA gene. A significant association was found between the number of VF and the XDR strains, regardless of the isolation sources. This study opens new research perspectives related to bacterial fitness and pathogenicity, and it provides new insights regarding the connection between biofilm formation, other virulence factors, and antibiotic resistance.

Unraveling topoisomerase IA gate dynamics in presence of PPEF and its preclinical evaluation against multidrug-resistant pathogens

Type IA topoisomerases maintain DNA topology by cleaving ssDNA and relaxing negative supercoils. The inhibition of its activity in bacteria prevents the relaxation of negative supercoils, which in turn impedes DNA metabolic processes leading to cell death. Using this hypothesis, two bisbenzimidazoles, PPEF and BPVF are synthesized, selectively inhibiting bacterial TopoIA and TopoIII. PPEF stabilizes the topoisomerase and topoisomerase-ssDNA complex, acts as an interfacial inhibitor. PPEF display high efficacy against ~455 multi-drug resistant gram positive and negative bacteria. To understand molecular mechanism of inhibition of TopoIA and PPEF, accelerated MD simulation is carried out, and results suggested that PPEF binds, stabilizes the closed conformation of TopoIA with –6Kcal/mol binding energy and destabilizes the binding of ssDNA. The TopoIA gate dynamics model can be used as a tool to screen TopoIA inhibitors as therapeutic candidates. PPEF and BPVF cause cellular filamentation and DNA fragmentation leading to bacterial cell death. PPEF and BPVF show potent efficacy against systemic and neutropenic mouse models harboring E. coli, VRSA, and MRSA infection without cellular toxicity.