Multidrug-resistant Gram-negative Bacteria Research Articles

Synergistic antibacterial effects of closantel and its enantiomers in combination with colistin against multidrug resistant gram-negative bacteria.

Drug combinations and repurposing have recently provided promising alternatives to cope with the increasingly severe issue of antibiotic resistance and depletion of natural drug molecular repertoires that undermine traditional antibacterial strategies. Closantel, an effective adjuvant, reverses antibiotic resistance in gram-negative bacteria. Herein, the combined antibacterial enantioselectivity of closantel is presented through separate enantiomer studies. Despite yielding unexpected differences, two closantel enantiomers (R, S) increased colistin activity against gram-negative bacteria both in vitro and in vivo. The fractional inhibitory concentration indices of R-closantel and S-closantel combined with colistin against Pseudomonas aeruginosa, Klebsiella pneumoniae, and Escherichia coli ranged from 0.0087 to 0.5004 and from 0.0117 to 0.5312, respectively. This difference was further demonstrated using growth inhibition assays and time-killing curves. Mechanistically, a higher intracellular concentration of R-CLO is more effective in enhancing the antimicrobial activity of combination. A mouse cutaneous infection model confirmed the synergistic stereoselectivity of closantel. This discovery provides novel insights for developing precision medication and containment of increasing antibiotic resistance.

Flavomycin restores colistin susceptibility in multidrug-resistant Gram-negative bacteria.

Colistin is a critical antibiotic in combating multi-drug resistant Gram-negative bacteria, but the emergence of mobilized colistin resistance (mcr) undermines its effectiveness. Previous studies have found that colistin can synergy with various drugs; however, its exact mechanisms with hydrophobic drugs are still unrevealed. Generally, the membrane destruction of colistin is thought to be the essential trigger for its interactions with its partner drugs. Here, we use clustered regularly interspaced palindromic repeats (CRISPR)-CRISPR-associated protein 9 (Cas9) for specifically mutating the binding site of one hydrophobic drug (flavomycin) and show that antimicrobial activity of flavomycin is critical for the synergy. Our results first give the evidence that the synergy is set off by colistin's membrane destruction and operated the final antimicrobial function by its partner drugs.

Antibacterial activity and antibiotic-potentiating effects of methanol extracts from Ocimum basilicum and Sarcocephalus latifolius against multidrug-resistant Gram-negative bacteria overexpressing efflux pumps

Antibacterial activity and antibiotic-potentiating effects of methanol extracts from Ocimum basilicum and Sarcocephalus latifolius against multidrug-resistant Gram-negative bacteria overexpressing efflux pumps

Addressing the Global Threat of Multidrug-Resistant Infections: The Role of Ceftazidime-Avibactam Revisited.

Background and objective Bloodstream infections (BSIs) due to multidrug-resistant Gram-negativebacteria(MDR-GNB) pose a significant global health threat amid rising antimicrobial resistance (AMR). This study aimed to investigatethe efficacy of ceftazidime-avibactam (CZA) as a therapeutic option for these infections, addressing the urgent need for novel treatments. Materials and methods This study was conducted over one year in the Department of Microbiology, JSS Medical College and Hospital, Mysuru, India, and employed a laboratory-based prospective design. From a total of 376 positive blood cultures, 147 multidrug-resistant (MDR) organisms were identified, and 100 were randomly selected for final analysis. Susceptibility testing via disk diffusion and minimum inhibitory concentration (MIC) determination was performed to evaluate CZA efficacy. Results Klebsiella pneumoniae (K. pneumoniae)was the predominant (78%) organism among the subsets, with varying susceptibility patterns observed across species. The overall CZA susceptibility was 45%, with significant discrepancies between disk diffusion and gold standard testing. Notably, there was limited efficacy against Pseudomonas aeruginosa (P.aeruginosa) Conclusions This study underscores the pressing need for reliable testing methods and novel treatment strategies in combating MDR infections. Further research with larger sample sizes is imperative to validate our findings and guide clinicians effectively in addressing this critical health challenge.

Evaluating the Metabolomic Profile and Anti-Pathogenic Properties of Cannabis Species.

The Cannabis species is one of the potent ancient medicinal plants acclaimed for its medicinal properties and recreational purposes. The plant parts are used and exploited all over the world for several agricultural and industrial applications. For many years Cannabis spp. has proven to present a highly diverse metabolomic profile with a pool of bioactive metabolites used for numerous pharmacological purposes ranging from anti-inflammatory to antimicrobial. Cannabis sativa has since been an extensive subject of investigation, monopolizing the research. Hence, there are fewer studies with a comprehensive understanding of the composition of bioactive metabolites grown in different environmental conditions, especially C. indica and a few other Cannabis strains. These pharmacological properties are mostly attributed to a few phytocannabinoids and some phytochemicals such as terpenoids or essential oils which have been tested for antimicrobial properties. Many other discovered compounds are yet to be tested for antimicrobial properties. These phytochemicals have a series of useful properties including anti-insecticidal, anti-acaricidal, anti-nematicidal, anti-bacterial, anti-fungal, and anti-viral properties. Research studies have reported excellent antibacterial activity against Gram-positive and Gram-negative multidrug-resistant bacteria as well as methicillin-resistant Staphylococcus aureus (MRSA). Although there has been an extensive investigation on the antimicrobial properties of Cannabis, the antimicrobial properties of Cannabis on phytopathogens and aquatic animal pathogens, mostly those affecting fish, remain under-researched. Therefore, the current review intends to investigate the existing body of research on metabolomic profile and anti-microbial properties whilst trying to expand the scope of the properties of the Cannabis plant to benefit the health of other animal species and plant crops, particularly in agriculture.

3-O-Substituted Quercetin: an Antibiotic-Potentiating Agent against Multidrug-Resistant Gram-Negative Enterobacteriaceae through Simultaneous Inhibition of Efflux Pump and Broad-Spectrum Carbapenemases.

The discovery of safe and efficient inhibitors against efflux pumps as well as metallo-β-lactamases (MBL) is one of the main challenges in the development of multidrug-resistant (MDR) reversal agents which can be utilized in the treatment of carbapenem-resistant Gram-negative bacteria. In this study, we have identified that introduction of an ethylene-linked sterically demanding group at the 3-OH position of the previously reported MDR reversal agent di-F-Q endows the resulting compounds with hereto unknown multitarget inhibitory activity against both efflux pumps and broad-spectrum β-lactamases including difficult-to-inhibit MBLs. A molecular docking study of the multitarget inhibitors against efflux pump, as well as various classes of β-lactamases, revealed that the 3-O-alkyl substituents occupy the novel binding sites in efflux pumps as well as carbapenemases. Not surprisingly, the multitarget inhibitors rescued the antibiotic activity of a carbapenem antibiotic, meropenem (MEM), in NDM-1 (New Delhi Metallo-β-lactamase-1)-producing carbapenem-resistant Enterobacteriaceae (CRE), and they reduced MICs of MEM more than four-fold (synergistic effect) in 8-9 out of 14 clinical strains. The antibiotic-potentiating activity of the multitarget inhibitors was also demonstrated in CRE-infected mouse model. Taken together, these results suggest that combining inhibitory activity against two critical targets in MDR Gram-negative bacteria, efflux pumps, and β-lactamases, in one molecule is possible, and the multitarget inhibitors may provide new avenues for the discovery of safe and efficient MDR reversal agents.

NhaA: A promising adjuvant target for colistin against resistant Escherichia coli

The emergence and widespread of multidrug-resistant Gram-negative bacteria have posed a severe threat to human health and environmental safety, escalating into a global medical crisis. Utilization of antibiotic adjuvants is a rapid approach to combat bacterial resistance effectively since the development of new antimicrobial agents is a formidable challenge. NhaA, driven by proton motive force, is a crucial secondary transporter on the cytoplasmic membrane of Escherichia coli. We found that 2-Aminoperimidine (2-AP), which is a specific inhibitor of NhaA, could enhance the activity of colistin against sensitive E. coli and reverse the resistance in mcr-1 positive E. coli. Mechanistic studies indicated that 2-AP induced dysfunction in cytoplasmic membrane through the suppression of NhaA, leading to metabolic inhibition and ultimately enhancing the sensitivity of E. coli to colistin. Moreover, 2-AP restored the efficacy of colistin against resistant E. coli in two animal infection models. Our findings reveal the potential of NhaA as a novel target for colistin adjuvants, providing new possibilities for the clinical application of colistin.

Antimicrobial efficacy of Punica granatum Lythraceae peel extract against pathogens belonging to the ESKAPE group.

The improper use and abuse of antibiotics have led to an increase in multidrug-resistant (MDR) bacteria resulting in a failure of standard antibiotic therapies. To date, this phenomenon represents a leading public health threat of the 21st century which requires alternative strategies to fight infections such as the identification of new molecules active against MDR strains. In the last 20 years, natural extracts with biological activities attracted scientific interest. Following the One Health Approach, natural by-products represent a sustainable and promising alternative solution. Consistently, the aim of the present study was to evaluate the antimicrobial activity of hydro-alcoholic pomegranate peel extract (PPE) against MDR microorganisms belonging to Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp. "ESKAPE" group pathogens. Through semiquantitative and quantitative methods, the PPE showed effective antimicrobial activity against Gram-positive and Gram-negative MDR bacteria. The kinetics of bactericidal action of PPE highlighted that microbial death was achieved in a time- and dose-dependent manner. High concentrations of PPE exhibited antioxidant activity, providing a protective effect on cellular systems and red blood cell membranes. Finally, we report, for the first time, a significant intracellular antibacterial property of PPE as highlighted by its bactericidal action against the staphylococcal reference strain and its bacteriostatic effect against clinical resistant strain in the HeLa cell line. In conclusion, due to its characterized content of polyphenolic compounds and antioxidant activity strength, the PPE could be considered as a therapeutic agent alone or in conjunction with standard antibiotics against challenging infections caused by ESKAPE pathogens.

Discovery of YFJ-36: Design, Synthesis, and Antibacterial Activities of Catechol-Conjugated β-Lactams against Gram-Negative Bacteria.

Cefiderocol is the first approved catechol-conjugated cephalosporin against multidrug-resistant Gram-negative bacteria, while its application was limited by poor chemical stability associated with the pyrrolidinium linker, moderate potency against Klebsiella pneumoniae and Acinetobacter baumannii, intricate procedures for salt preparation, and potential hypersensitivity. To address these issues, a series of novel catechol-conjugated derivatives were designed, synthesized, and evaluated. Extensive structure-activity relationships and structure-metabolism relationships (SMR) were conducted, leading to the discovery of a promising compound 86b (Code no. YFJ-36) with a new thioether linker. 86b exhibited superior and broad-spectrum in vitro antibacterial activity, especially against A. baumannii and K. pneumoniae, compared with cefiderocol. Potent in vivo efficacy was observed in a murine systemic infection model. Furthermore, the physicochemical stability of 86b in fluid medium at pH 6-8 was enhanced. 86b also reduced potential the risk of allergy owing to the quaternary ammonium linker. The improved properties of 86b supported its further research and development.

Design, Synthesis, and Biological Evaluation of Novel Arylomycins against Multidrug-Resistant Gram-Negative Bacteria.

G0775, an arylomycin-type SPase I inhibitor that is being evaluated in a preclinical study, exhibited potent antibacterial activities against some Gram-negative bacteria but meanwhile suffered defects such as a narrow antibacterial spectrum and poor pharmacokinetic properties. Herein, systematic structural modifications were carried out, including optimization of the macrocyclic skeleton, warheads, and lipophilic regions. The optimization culminated in the discovery of 138f, which showed more potent activity and a broader spectrum against clinically isolated carbapenem-resistant Gram-negative bacteria, especially against Acinetobacter baumannii and Pseudomonas aeruginosa. 162, the free amine of 138f, exhibited an excellent pharmacokinetic profile in rats. In a neutropenic mouse thigh model of infection with multidrug-resistant P. aeruginosa, the potent in vivo antibacterial efficacy of 162 was confirmed and superior to that of G0775 (3.5-log decrease vs 1.1-log decrease in colony-forming unit (CFU)). These results support 162 as a potential antimicrobial agent for further research.

Development of a multiplex real-time PCR assay for simultaneous detection of common colistin and carbapenemase genes

Carbapenem and colistin are often used as last-resort treatment for Gram-negative multi-drug resistant (MDR) bacteria. Nevertheless, co-resistance of these drugs is threatening the global healthcare system. Rapid and accurate detection of carbapenem and colistin resistant bacteria is critical for adequate antibiotic therapy and infection control, particularly in the context of an outbreak. The presence of blaNDM, blaKPC, blaIMP-1 and blaOXA-48 is responsible for greater than 95% phenotypic resistance in carbapenem-resistant Enterobacteriaceae, while mcr-1 is the most prevalent and well disseminated of all mcr genes in colistin-resistant strains. In this study, we aim to develop a multiplex real time-PCR assay for simultaneous detection of the five genes blaNDM, blaKPC, blaIMP-1, blaOXA-48 and mcr-1. The melting curve-based multiplex real time PCR assay was established with the dissociation temperature range extended from 76°C to 87°C. The whole process is completed within one hour and half, allowing rapid screening of the five genes in cultured bacteria samples with a limit of detection of 10 CFU/ml. The proposed multiplex real-time PCR assay is a robust, reliable and rapid method for the detection of bacterial strains carrying blaOXA-48, blaIMP, blaNDM, blaKPC and mcr-1 gene individually or in cocktail of genes. This assay will be a valuable tool for surveillance and monitoring of MDR bacteria additionally resistant to either carbapenem or colistin or both drugs.

The significance of monitoring respiratory sample cultures and polymerase chain reaction tests for detecting bacterial pathogens in severely and critically ill patients with COVID-19

Background. Bacterial superinfection is one of the most common and potentially lethal complications in severely and critically ill patients with COVID-19. Objectives. To determine the colonisation time frame and the spectrum of potential bacterial pathogens in respiratory samples from patients with severe and critical COVID-19, using routine culture and polymerase chain reaction (PCR) tests. Methods. A prospective observational study was conducted on patients aged ≥18 years with confirmed severe and critical COVID-19 who were admitted to or transferred to the intensive care unit (ICU). Respiratory samples were collected for microbial culture and PCR testing within the first 2 days after ICU admission/transfer, between days 3 and 6, and after 7 days of ICU stay. Results. A total of 82 patients, with a median (interquartile range) age of 74.5 (67.3 - 81.0) years and a median Charlson comorbidity index of 4 (3 - 5), were enrolled in the study. Colonisation with any pathogen was observed in 67% of patients, after a median of 4 (2 - 6) days in the ICU. On days 0 - 2 of the ICU stay, micro-organisms were detected in 18% of patients, with Klebsiella pneumoniae (without acquired antibiotic resistance) and methicillin-susceptible Staphylococcus aureus being most frequently identified. Later, Acinetobacter baumannii and carbapenem-resistant K. pneumoniae became the predominant micro-organisms, identified in nearly half of the patients. In 74% of the samples, the results of microbial culture and PCR tests were identical. In 17%, PCR revealed bacterial pathogens not identified by culture. Conclusion. Our study confirms that colonisation of the respiratory tract occurs early in the course of ICU stay. Superinfections are predominantly caused by multidrug-resistant Gram-negative bacteria.

Combinatorial metabolic engineering of Bacillus subtilis for de novo production of polymyxin B

Polymyxin is a lipopeptide antibiotic that is effective against multidrug-resistant Gram-negative bacteria. However, its clinical development is limited due to low titer and the presence of homologs. To address this, the polymyxin gene cluster was integrated into Bacillus subtilis, and sfp from Paenibacillus polymyxa was expressed heterologously, enabling recombinant B. subtilis to synthesize polymyxin B. Regulating NRPS domain inhibited formation of polymyxin B2 and B3. The production of polymyxin B increased to 329.7 mg/L by replacing the native promoters of pmxA, pmxB, and pmxE with PfusA, C2up, and PfusA, respectively. Further enhancement in this production, up to 616.1 mg/L, was achieved by improving the synthesis ability of 6-methyloctanoic acid compared to the original strain expressing polymyxin heterologously. Additionally, incorporating an anikasin-derived domain into the hybrid nonribosomal peptide synthase of polymyxin increased the B1 ratio in polymyxin B from 57.5% to 62.2%. Through optimization of peptone supply in the fermentation medium and fermentation in a 5.0-L bioreactor, the final polymyxin B titer reached 962.1 mg/L, with a yield of 19.24 mg/g maltodextrin and a productivity of 10.02 mg/(L·h). This study demonstrates a successful approach for enhancing polymyxin B production and increasing the B1 ratio through combinatorial metabolic engineering.

Molecular detection of antimicrobial resistance genes in multidrug-resistant Gram-negative bacteria isolated from clinical samples in two hospitals in Niger

Background: According to the World Health Organization (WHO), bacterial resistance to antibiotics is a global public health challenge, which is also developing in Niger. The aim of this study was to determine the prevalence of antibiotic resistance genes in Gram-negative bacilli isolated from clinical samples in the biological laboratories of two selected health facilities in Niger.
 Methodology: Clinical bacterial isolates were randomly collected from two biological laboratories of Zinder National Hospital and Niamey General Reference Hospital. These were multi-resistant Gram-negative bacteria that have been routinely isolated from pathological samples of patients. Molecular detection of resistance genes was carried out by polymerase chain reaction (PCR) amplification using specific primers. These include plasmid-mediated AmpC beta lactamase genes (blaCITM, blaDHAM, blaFOXM), ‘Cefotaxime-Munich’ type beta lactamase genes (blaCTX-M-1, blaCTX-M-2, blaCTX-M-9), KPC-type beta lactamase gene (blaKPC), Oxa-type beta lactamase gene (blaOXA-48), SHV-type beta lactamase gene (blaSHV), TEM-type beta lactamase gene (blaTEM), quinolone resistance genes (qnrA, qnrB, qnrS), and sulfonamide resistance genes (sul1, sul2, sul3).
 Results: A total of 24 strains of multidrug-resistant Gram-negative bacteria isolated from different clinical samples were analysed. The distribution of the resistance genes detected is as follows; AmpC blaCITM (n=6; 25.0%), AmpC blaDHAM (n=4; 17.0%), AmpC blaFOXM (n=0), blaCTX-M-1 (n=11; 46.0%), blaCTX-M-2 (n=0), blaCTX-M-9 (n=0), blaKPC (n=0), blaOXA-48 (n=2; 8..0%), blaSHV (n=5; 21.0%), blaTEM (n=0), qnrA (n=0), qnrB (n=5; 21.0%), qnrS (n=17; 71.0%), sul1 (n=22; 92.0%), sul2 (n=12; 50.0%), and sul3 (n=0). All isolates tested had at least two resistance genes.
 Conclusion: The results of this study provide a better understanding of the resistance situation of clinical isolates in Niger. Therefore, it is more than necessary to intensify the detection on a larger number of samples and on a national scale. This will make it possible to assess the true extent of the phenomenon and consequently guide control strategies through a national multisectoral plan.
 Contexte: Selon l'Organisation Mondiale de la Santé (OMS), la résistance bactérienne aux antibiotiques constitue un défi mondial de santé publique, qui se développe également au Niger. Le but de cette étude était de déterminer la prévalence des gènes de résistance aux antibiotiques chez les bacilles Gram négatif isolés à partir d'échantillons cliniques dans les laboratoires de biologie de deux formations sanitaires sélectionnées au Niger.
 Méthodologie: Des isolats bactériens cliniques ont été collectés de manière aléatoire dans deux laboratoires de biologie de l'Hôpital National de Zinder et de l'Hôpital Général de Référence de Niamey. Il s’agissait de bactéries Gram-négatives multirésistantes qui ont été systématiquement isolées à partir d’échantillons pathologiques de patients. La détection moléculaire des gènes de résistance a été réalisée par amplification par réaction en chaîne par polymérase (PCR) à l'aide d'amorces spécifiques. Il s'agit notamment des gènes de bêta-lactamase AmpC à médiation plasmidique (blaCITM, blaDHAM, blaFOXM), des gènes de bêta-lactamase de type «Céfotaxime-Munich» (blaCTX-M-1, blaCTX-M-2, blaCTX-M-9), du gène de bêta-lactamase de type KPC (blaKPC), du gène de bêta-lactamase de type Oxa (blaOXA-48), le gène bêta-lactamase de type SHV (blaSHV), le gène bêta-lactamase de type TEM (blaTEM), les gènes de résistance aux quinolones (qnrA, qnrB, qnrS) et les gènes de résistance aux sulfamides (sul1, sul2, sul3).
 Résultats: Au total, 24 souches de bactéries Gram-négatives multirésistantes isolées de différents échantillons cliniques ont été analysées. La répartition des gènes de résistance détectés est la suivante; AmpC blaCITM (n=6; 25,0%), AmpC blaDHAM (n=4; 17,0%), AmpC blaFOXM (n=0), blaCTX-M-1 (n=11; 46,0%), blaCTX-M-2 (n=0), blaCTX-M-9 (n=0), blaKPC (n=0), blaOXA-48 (n=2; 8,0%), blaSHV (n=5; 21,0%), blaTEM (n=0), qnrA (n=0), qnrB (n=5; 21,0%), qnrS (n=17; 71,0%), sul1 (n=22; 92,0%), sul2 (n=12; 50,0%) et sul3 (n=0). Tous les isolats testés possédaient au moins deux gènes de résistance.
 Conclusion: Les résultats de cette étude permettent de mieux comprendre la situation de résistance des isolats cliniques au Niger. Il est donc plus que nécessaire d’intensifier la détection sur un plus grand nombre d’échantillons et à l’échelle nationale. Cela permettra d'évaluer l'ampleur réelle du phénomène et par conséquent d'orienter les stratégies de lutte à travers un plan national multisectoriel.

Use of Cefiderocol in the Management of Children With Infection or Colonization With Multi-drug Resistant Gram-negative Bacteria: A Retrospective, Single-center Case Series.

Cefiderocol, a novel siderophore cephalosporin, represents a treatment option for infections with multidrug-resistant Gram-negative bacteria, of which rates are rising worldwide. Clinical data on its use in children is limited. In our pediatric case series, the largest reported to date, cefiderocol seems safe and well tolerated, with more favorable clinical outcomes when compared to the literature reviewing adult cases.

Analysis of factors influencing the risk of secondary infection in patients colonized or infected with multidrug-resistant Gram-negative bacteria following hospitalization

We seek to investigate the multifaceted factors influencing secondary infections in patients with multidrug-resistant Gram-negative bacteria (MDR-GNB) colonization or infection post-hospitalization. A total of 100 patients with MDR-GNB colonization or infection were retrospectively reviewed, encompassing those admitted to both the general ward and intensive care unit of our hospital from August 2021 to December 2022. Patients were categorized into the control group (non-nosocomial infection, n = 56) and the observation group (nosocomial infection, n = 44) based on the occurrence of nosocomial infection during hospitalization. Clinical data were compared between the two groups, including the distribution and antibiotic sensitivity of MDR-GNB before nosocomial infection. Significant differences were observed between the two groups in terms of age, underlying diseases, immune status, length of stay, and invasive medical procedures (P < 0.05). The observation group also had fewer patients practicing optimized hygiene, strict isolation, and antibiotic control than the control group (P < 0.05). Factors influencing the risk of secondary infection after hospitalization in patients colonized or infected with MDR-GNB included patient age, underlying diseases, immune status, length of hospitalization, medical invasive procedures, optimized hygiene, strict isolation, and antibiotic control (P < 0.05). The length of hospitalization and treatment cost in the observation group were higher than those in the control group (P < 0.05). This study comprehensively analyzes the intricate mechanisms of secondary infections in patients with MDR-GNB infections post-hospitalization. Key factors influencing infection risk include patient age, underlying diseases, immune status, length of hospitalization, medical invasive procedures, optimized hygiene, strict isolation, and antibiotic control.

Recent Trends of Antibiotic Resistance Patterns of Gram-negative Bacteria Collected from Clinical Isolates in Dhaka City

Abstract BACKGROUND: Gram-negative bacteria responsible for a significant rise in antimicrobial resistance over the past 20 years. This alarming resistance has been linked to increased mortality and health-care costs, particularly for patients, clinicians, and the health-care system. Gram-negative bacteria cause a wide range of infectious diseases including gastrointestinal tract infections, urinary tract infections, respiratory tract infections, meningitis, typhoid fever, shigellosis, bacteremia, and septicemia. METHODS: A total of 220 different clinical specimens were collected between October 2022 and November 2023 from various renowned diagnostic centers of Dhaka, Bangladesh. According to the study plan, 199 Gram-negative bacterial isolates were collected, transported, and processed in the Microbiology Laboratory of Stamford University Bangladesh. RESULTS: The study found that female patients were predominant than male patients except for the Proteus cases. Escherichia coli was highly resistant to various antibiotics, with resistance levels ranging from 100% to 66%, although colistin was found effective. Azithromycin was the most ineffective antibiotic against Klebsiella, with 100% resistance. Other antibiotics showed high resistance, although colistin and imipenem showed effective sensitivity. High resistance levels were observed in azithromycin, colistin, doxycycline, nalidixic acid, co-trimoxazole, nitrofurantoin, cefuroxime, and amoxyclave for Proteus-infected patients, although some antibiotics showed effective sensitivity. However, Acinetobacter isolates were also found with high resistance levels across all age groups. For Pseudomonas cases, amoxyclav, nitrofurantoin, and cotrimoxazole were the most ineffective antibiotics, but colistin, ceftazidime, piperacillin, meropenem, and amikacin showed satisfactory efficacy. CONCLUSION: The study reveals alarming multidrug resistance in Gram-negative bacteria in Dhaka, raising public health concerns. Age and gender should be considered when selecting antibiotics.

Structural Insights into the Lipopolysaccharide Transport (Lpt) System as a Novel Antibiotic Target.

Lipopolysaccharide (LPS) is a critical component of the extracellular leaflet within the bacterial outer membrane, forming an effective physical barrier against environmental threats in Gram-negative bacteria. After LPS is synthesized and matured in the bacterial cytoplasm and the inner membrane (IM), LPS is inserted into the outer membrane (OM) through the ATP-driven LPS transport (Lpt) pathway, which is an energy-intensive process. A trans-envelope complex that contains seven Lpt proteins (LptA-LptG) is crucial for extracting LPS from the IM and transporting it across the periplasm to the OM. The last step in LPS transport involves the mediation of the LptDE complex, facilitating the insertion of LPS into the outer leaflet of the OM. As the Lpt system plays an essential role in maintaining the impermeability of the OM via LPS decoration, the interactions between these interconnected subunits, which are meticulously regulated, may be potential targets for the development of new antibiotics to combat multidrug-resistant Gram-negative bacteria. In this review, we aimed to provide an overview of current research concerning the structural interactions within the Lpt system and their implications to clarify the function and regulation of LPS transport in the overall process of OM biogenesis. Additionally, we explored studies on the development of therapeutic inhibitors of LPS transport, the factors that limit success, and future prospects.

Prevalence of multidrug-resistant bacterial infections in diabetic foot ulcers: A meta-analysis.

Multidrug-resistant (MDR) bacterial infections have become increasingly common in recent years due to the increased prevalence of diabetic foot ulcers (DFUs). We carried out a meta-analysis aimed at investigating the prevalence of MDR bacteria isolated from DFUs and analysing the risk factors for MDR bacterial infection in patients with DFUs. The PubMed/Medline, Web of Science, Embase, Cochrane Library, Ovid, Scopus, and ProQuest databases were searched for studies published up to November 2023 on the clinical outcomes of MDR bacteria in DFUs. The main outcome was the prevalence of MDR bacteria in DFUs. A total of 21 studies were included, representing 4885 patients from which 2633 MDR bacterial isolates were obtained. The prevalence of MDR bacteria in DFUs was 50.86% (95% confidence interval (CI): 41.92%-59.78%). The prevalence of MDR gram-positive bacteria (GPB) in DFUs was 19.81% (95% CI: 14.35%-25.91%), and the prevalence of MDR gram-negative bacteria (GNB) in DFUs was 32.84% (95% CI: 26.40%-39.62%). MDR Staphylococcus aureus (12.13% (95% CI: 8.79%-15.91%)) and MDR Enterococcus spp. (3.33% (95% CI: 1.92%-5.07%)) were the main MDR-GPB in DFUs. MDR Escherichia coli, MDR Pseudomonas aeruginosa, MDR Enterobacter spp., MDR Klebsiella pneumoniae, and MDR Proteus mirabilis were the main MDR-GNB in DFUs. The prevalence rates were 6.93% (95% CI: 5.15%-8.95%), 6.01% (95% CI: 4.03%-8.33%), 3.59% (95% CI: 0.42%-9.30%), 3.50% (95% CI: 2.31%-4.91%), and 3.27% (95% CI: 1.74%-5.21%), respectively. The clinical variables of diabetic foot ulcer patients infected with MDR bacteria and non-MDR bacteria in the included studies were analysed. The results showed that peripheral vascular disease, peripheral neuropathy, nephropathy, osteomyelitis, Wagner's grade, previous hospitalization and previous use of antibacterial drugs were significantly different between the MDR bacterial group and the non-MDR bacterial group. We concluded that there is a high prevalence of MDR bacterial infections in DFUs. The prevalence of MDR-GNB was greater than that of MDR-GPB in DFUs. MDR S. aureus was the main MDR-GPB in DFUs, and MDR E. coli was the main MDR-GNB in DFUs. Our study also indicated that peripheral vascular disease, peripheral neuropathy, nephropathy, osteomyelitis, Wagner's grade, previous hospitalization, and previous use of antibacterial drugs were associated with MDR bacterial infections in patients with DFUs.

Epidemiology, Clinical, and Microbiological Characteristics of Multidrug-Resistant Gram-Negative Bacteremia in Qatar.

Antimicrobial resistance is a global healthcare threat with significant clinical and economic consequences peaking at secondary and tertiary care hospitals where multidrug-resistant Gram-negative bacteria (MDR GNB) lead to poor outcomes. A prospective study was conducted between January and December 2019 for all invasive bloodstream infections (BSIs) secondary to MDR GNB in Qatar identified during routine microbiological service to examine their clinical, microbiological, and genomic characteristics. Out of 3238 episodes of GNB BSIs, the prevalence of MDR GNB was 13% (429/3238). The predominant MDR pathogens were Escherichia coli (62.7%), Klebsiella pneumoniae (20.4%), Salmonella species (6.6%), and Pseudomonas aeruginosa (5.3%), while out of 245 clinically evaluated patients, the majority were adult males, with the elderly constituting almost one-third of the cohort and with highest observed risk for prolonged hospital stays. The risk factors identified included multiple comorbidities, recent healthcare contact, previous antimicrobial therapy, and admission to critical care. The in-hospital mortality rate was recorded at 25.7%, associated with multiple comorbidities, admission to critical care, and the acquisition of MDR Pseudomonas aeruginosa. Resistant pathogens demonstrated high levels of antimicrobial resistance but noticeable susceptibility to amikacin and carbapenems. Genomic analysis revealed that Escherichia coli ST131 and Salmonella enterica ST1 were the predominant clones not observed with other pathogens.