Resistant Strains Research Articles

Phages adapt to recognize an O-antigen polysaccharide site by mutating the ‘backup’ tail protein ORF59, enabling reinfection of phage-resistant Klebsiella pneumoniae

Phages demonstrate remarkable promise as antimicrobial agents against antibiotic-resistant bacteria. However, the emergence of phage-resistant strains poses challenges to their effective application. In this paper, we presented the isolation of a phage adaptive mutant that demonstrated enhanced and sustained antibacterial efficacy through the co-evolution of Klebsiella pneumoniae (K. pneumoniae) 111-2 and phage ZX1Δint in vitro. Our experiments revealed that phage ZX1Δint successfully completed the adsorption phase by binding to the host surface, specifically targeting the capsular polysaccharide (CPS) receptor via the primary receptor-binding protein (RBP) ORF60 and the auxiliary RBP ORF59. Upon exposure to phage predation, mutations in genes wbaP, wbaZ or wzc, which encode the synthesis of the CPS, conferred resistance by reducing phage adsorption. In response to these host defense mechanisms, the adaptive mutant phages have evolved to utilize an alternative binding site located on an O-antigen site of lipopolysaccharide (LPS) through a mutation in the backup RBP ORF59. This evolutionary change enabled the phages to reinfect previously phage-resistant strains. Notably, the adaptive mutant phage PR2 carrying the ORF59 mutation Q777R, demonstrated the capacity to infect both wild-type and resistant strains, exhibiting prolonged antimicrobial activity against the wild strains. In conclusion, our findings elucidated a complex phage-host adsorption-antagonism mechanism characterized by mutation-driven alterations in phage receptor recognition. This work contributes to a deeper understanding of phage adaptability and highlights the potential for phages to combat phage-resistant bacteria through an in vitro evolutionary approach.

ARGai 2.0: A Feature Engineering Enabled Deep Network Model for Antibiotic Resistance Gene and Strain Identification in E. coli

ARGai 2.0: A Feature Engineering Enabled Deep Network Model for Antibiotic Resistance Gene and Strain Identification in E. coli

Design and development of pyrazol-5-ylbenzamide derivatives containing chiral oxazoline moiety as fungicides based on molecular docking.

Development of novel chiral antifungal agents for effective control of plant pathogens is urgently needed. In this study, a series of pyrazol-5-yl-benzamide derivatives containing chiral oxazoline moiety were rationally designed and developed based on molecular docking. The in vitro antifungal assay results indicated that compounds (rac)-4h (R1 = Et), (S)-4 h (R1 = S-Et) and (R)-4 h (R1 = R-Et) exhibited remarkable antifungal activities against Valsa mali with median effective concentration (EC50) values of 0.24, 0.06 and 1.08 mg/L, respectively. Preliminary structure-activity relationships (SARs) revealed that the modification of the chiral substituent group at the oxazoline moiety significantly affected the antifungal activities of the target compounds. Furthermore, compounds (S)-4h (87.5%) and (R)-4h (84.3%) exhibited in vivo protective activities comparable to tebuconazole (87.5%) against V. mali. Subsequent molecular docking analysis, succinate dehydrogenase (SDH) enzyme inhibition assays and molecular dynamic (MD) simulations verified that the potential target enzyme of this class of derivatives could be SDH and helped to explain the large difference in antifungal activities of compounds (S)-4h and (R)-4h. Confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM) observations confirmed that these two compounds severely disrupted the mycelial morphology of V. mali. Theoretical calculation studies provided some insight into the subsequent modification of such pyrazol-5-yl-benzamide derivatives. Resistance frequency studies showed that (S)-4h and (R)-4h treatments were less likely to produce resistant fungal strains than tebuconazole. Meanwhile, compounds (S)-4h and (R)-4h exhibited no apparent toxicity to the Apis mellifera L. Therefore, these derivatives are potential candidates for the development of novel chiral fungicides for crop protection. © 2025 Society of Chemical Industry.

Exploring Antibacterial Properties of Marine Sponge-Derived Natural Compounds: A Systematic Review

The rise in multidrug-resistant (MDR) bacteria has prompted extensive research into antibacterial compounds, as these resistant strains compromise current treatments. This resistance leads to prolonged hospitalization, increased mortality rates, and higher healthcare costs. To address this challenge, the pharmaceutical industry is increasingly exploring natural products, particularly those of marine origin, as promising candidates for antimicrobial drugs. Marine sponges, in particular, are of interest because of their production of secondary metabolites (SM), which serve as chemical defenses against predators and pathogens. These metabolites exhibit a wide range of therapeutic properties, including antibacterial activity. This systematic review examines recent advancements in identifying new sponge-derived compounds with antimicrobial activity, specifically targeting Pseudomonas aeruginosa, a prevalent Gram-negative pathogen with the highest incidence rates in clinical settings. The selection criteria focused on antimicrobial compounds with reported Minimum Inhibitory Concentration (MIC) values. The identified SM include alkaloids, sesterterpenoids, nitrogenous diterpene, and bromotyrosine-derived derivatives. The structural features of the active compounds selected in this review may provide a foundational framework for developing new, highly bioactive antimicrobial agents.

Prevalence and Antimicrobial Susceptibility of Mycoplasma hominis and Ureaplasma Species among Women in Dakar

Introduction: Genital mycoplasmas, which cause infections of the lower reproductive tract in women, are a major cause of morbidity and complications. The aim of this study was to determine the prevalence of mycoplasma infections and the antibiotic susceptibility profile among women in Dakar. Material and methods: We conducted a retrospective descriptive study over a four-year period, from 02 January 2018 to 31 December 2021. The study population consisted of women referred to the microbiology laboratory at Military Hospital of Ouakam for genital mycoplasma testing. The Mycoplasma IES kit was used for mycoplasma testing and susceptibility testing in accordance with the manufacturer's recommendations. Results: A total of 1431 patients were enrolled during the study period. The mean age was 32.6 ± 8.5 years. The overall prevalence of mycoplasma infection was 55.8% (798/1431). Of the 798 positive cultures, 52.8% were infected with Ureaplasma urealyticum (UU) and 17.9% with Mycoplasma hominis (MH). UU+MH co-infection was 31.08%. Analysis of the sensitivity profiles showed that UU was sensitive to most of the antibiotics used, while M. hominis strains showed low levels of resistance to tetracyclines (TET DOX, MIN), quinolones (OFX, LEV, SPA) and JOS. This resistance was much higher with macrolides (ERY, ROX, AZT), certain quinolones (ASP, CIP) and aminoglycosides (SPE). However, M. hominis strains were much more resistant to these molecules than U. urealitycum isolates. Conclusion: Our study revealed a high rate of genital mycoplasma infection among women in Dakar. The high rates of resistance to certain molecules underline the importance of surveillance to prevent transmission of resistant strains and rational use of antibiotics.

Syzygium aromaticum extract mediated, sustainable silver nanoparticle synergetic with heterocyclic antibiotic clarithromycin and their antimicrobial activities

Microorganisms are becoming resistant to drugs and antimicrobials, making it a significantly critical global issue. Nosocomial infections are resulting in alarmingly increasing rates of morbidity and mortality. Plant derived compounds hold numerous antimicrobial properties, making them a very capable source to counteract resistant microbial strains. Syzygium aromaticum (Clove) extract has been proven by studies to contain active ingredients that demonstrate antibacterial, antifungal, antioxidant, and insecticidal properties. It has also been used historically for its pain relief especially for tooth ache. Clove extract derived nanoparticle synthesis is a promising method of combining therapeutics with metals at nanoscale. Such nanostructured systems in combination with the heterocyclic antibiotic clarithromycin could potentiate the action of plant extracts, decrease drug side effects and improve antimicrobial activity. In this study, clove extract (C) was successfully used to synthesize silver nanoparticles (AgNP) to create AgNPC and AgNPCA (A = clarithromycin). The two compounds underwent different analytical methods consisting of SEM, EDS, DLS, UV-vis, FTIR and XRD. These nanoparticles were used against a variety of 10 pathogens and exhibited very good to intermediate antibacterial properties. AgNPC resulted in better antibacterial properties and smaller nanoparticle size. This study demonstrates the potential of clove extract mediated AgNP synthesis in combination with and without the antibiotic clarithromycin.

Targeting InhA in drug-resistant Mycobacterium tuberculosis: potent antimycobacterial activity of diaryl ether dehydrozingerone derivatives.

Tuberculosis (TB) remains a major global threat, with 10 million new cases and 1.5 million deaths each year. In multidrug-resistant tuberculosis (MDR-TB), resistance is most commonly observed against isoniazid (INH) and rifampicin (RIF), the two frontline drugs. Isoniazid resistance is predominantly linked to mutations in the InhA gene, which encodes an enzyme involved in mycolic acid synthesis, a vital component of the mycobacterial cell wall. Mutations in InhA reduce drug binding, rendering INH ineffective. These morbidity and mortality figures, along with the fact that the rise and global spread of drug-resistant TB, underscores the need for the discovery of novel therapeutics. In this direction, we have previously synthesized, characterized, and screened a library of diaryl ether dehydrozingerone derivatives against mycobacteria and identified two best hits, 7 and 14, based on bacteriostatic activities. The present study aimed to thoroughly investigate the antituberculosis potential of these compounds, particularly regarding drug-resistant TB. Our findings revealed that both compounds exhibited tuberculocidal activity against the standard laboratory strain Mycobacterium tuberculosis (M. tb) H37Rv, with minimal bactericidal concentrations (MBC) of 4μg/ml for compound 7 and 8μg/ml for compound 14. Next, concentration vs time-kill kinetics of both these compounds showed concentration-dependent bactericidal activities against M. tb and complete pathogen eradication from culture at just 16× MIC. Both compounds were found to be suitable for combination regimens as their interactions with isoniazid and rifampicin against M. tb were observed to be synergistic. Additionally, 7 and 14 exhibited minimal hemolysis against human RBCs and less cytotoxicity was observed against three human cell lines up to 1000μM. Molecular docking revealed that these compounds bind more effectively to M. tb InhA, including its mutant forms where isoniazid binding is impaired, outperforming both isoniazid and triclosan in binding affinity. Importantly 7 and 14 showed potent activity against drug-susceptible clinical isolates and two isoniazid-resistant M. tb clinical isolates equivalent to that against M. tb H37Rv. The most interesting observation was that both compounds were found to be effective against three multi-drug resistant (MDR) strains of M. tb, thereby depicting their potential against drug-resistant TB. An ex vivo assay on RAW 264 cells infected with M. tb demonstrated a significant reduction in bacterial load at 8× MIC, revealing the fact that these compounds are highly effective against intracellular M. tb H37Rv. To the best of our knowledge, this is the first study that reports promising antimycobacterial potential of 7 and 14 against drug-susceptible, isoniazid-resistant, and MDR tuberculosis which warrants further exploration considering the need for new anti-TB medicine.

A reduction-secretion system contributes to roxarsone (V) degradation and efflux in Brevundimonas sp. M20

Roxarsone (V) (Rox(V)) is an organoarsenical compound that poses significant risks to aquatic ecosystems and various diseases. Reducing trivalent 3-amino-4-hydroxyphenylarsonic acid (HAPA(III)) offers a competitive advantage; however, it leads to localized arsenic contamination, which can disrupt the soil microbiome and impede plant growth. Three genes, BsntrA, arsC2, and BsexpA, encoding nitroreductase, arsenate reductase, and MFS transporter, respectively, were identified in the Rox(V)-resistant strain Brevundimonas sp. M20. A three-step approach, including nitroreduction, As(V) reduction, and HAPA(III) secretion, which is responsible for roxarsone(V) resistance, was subsequently confirmed. Moreover, the flavonoid compound baicalin occupied the HAPA(III) delivery space and grabbed the R127 residues via stronger interactions. This steric hindrance prevented the transportation of HAPA(III) by BsexpA to the extracellular space. These results demonstrate a new Rox(V) reduction pathway, providing a potential efflux pump inhibitor to trap more toxins.

Bacteriophage Treatment Induces Phenotype Switching and Alters Antibiotic Resistance of ESBL Escherichia coli

Background/Objectives: Bacteriophage therapy represents a promising strategy to combat multidrug-resistant pathogens, such as Escherichia coli. In this study, we explored the effects of a bacteriophage infection on an Extended Spectrum Beta-Lactamase (ESBL) positive E. coli isolate. Methods: We used next generation sequencing, proteomics and phenotypic screens to investigate the effect of bacteriophage infections on E. coli metabolism and resistance phenotypes. Results: The bacteriophage infection led to notable alterations in colony morphology, indicating profound changes in bacterial metabolism. Proteomic analysis revealed significant shifts in protein expression, with 65 proteins upregulated and 246 downregulated post-infection. The downregulated proteins were involved in various metabolic pathways, including nucleic acid, protein and lipid metabolism, and iron acquisition. Bacteriophage treatment also led to increased bacterial membrane permeability. Altogether, these alterations in bacterial metabolism and membrane permeability may lead to a general reduction in antibiotic resistance. Indeed, the bacteriophage-infected E. coli exhibited increased sensitivity to various classes of antibiotics, including beta-lactams, fluoroquinolones, trimethoprim-sulfamethoxazole, and aminoglycosides. Conclusions: Our findings highlight the potential of bacteriophage therapy as an adjunct to existing antibiotics, enhancing their efficacy against resistant strains.

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.

Overexpression of multiple cytochrome P450 genes with and without knockdown resistance mutations confers high resistance to deltamethrin in Culex quinquefasciatus

BackgroundThe cytochrome P450s-mediated metabolic resistance and the target site insensitivity caused by the knockdown resistance (kdr) mutation in the voltage-gated sodium channel (vgsc) gene were the main mechanisms conferring resistance to deltamethrin in Culex quinquefasciatus from Thailand. This study aimed to investigate the expression levels of cytochrome P450 genes and detect mutations of the vgsc gene in deltamethrin-resistant Cx. quinquefasciatus populations in Thailand.MethodsTwo field-collected strains of Cx. quinquefasciatus, Cq_SP and Cq_NiH, were selected with deltamethrin to generate the resistant strains Cq_SP-R and Cq_NiH-R, respectively. Bioassays were tested on larvae and adults of each strain according to WHO methods. Eight cytochrome P450 genes were analyzed for the expression level using quantitative real time-PCR. The cDNA of mosquitoes was amplified and sequenced for four fragments of vgsc gene. The kdr L1014F mutation and the haplotype of the CYP9M10 gene were detected in survivor and dead mosquitoes after exposure to the deltamethrin WHO test paper. Statistical analyses were performed using Fisher’s exaction test.ResultsBioassay tests revealed a significantly higher resistance level in Cq_SP-R than in Cq_NiH-R strains in both larvae and adults. All eight cytochrome P450 genes were significantly overexpressed in larvae of Cq_NiH-R strain compared to the parent and susceptible Cq_Sus strains. The CYP6AA7 and CYP9J34 genes had the highest expression ratios, exceeding 24-fold in Cq_NiH-R larvae. In Cq_SP-R strain, the CYP4H34 and CYP9J34 genes were overexpressed in both stages. The kdr L1014F mutation was found in Cq_SP-R and its parent Cq_SP strains with a significantly higher mutant allele frequency in the survivor mosquitoes than in dead mosquitoes (P < 0.0001). The V240M and novel L925F mutations were found only in Cq_SP-R strain. Heterozygous genotype for the D-Cu( +)/Cu(–) of CYP9M10 gene was detected in Cq_NiH and Cq_NiH-R strains but other strains were mostly homozygous for the Cu(–)/Cu(–).ConclusionsOverexpression of multiple cytochrome P450 genes alone has a relatively minor impact on resistance. The combined mechanisms of cytochrome P450- and kdr-mediated resistance result in significantly higher resistance to deltamethrin in Cx. quinquefasciatus. This study supports sustainable public health initiatives in Thailand to address the evolving challenges of insecticide resistance.

Clinical and molecular analysis of ESBL, carbapenemase, and colistin-resistant bacteria in UTI patients.

Uropathogens, particularly bacteria, can infect any part of the urinary tract and cause bacteriuria. Our study aimed to examine the antibiotic-resistant profile, associated risk factors, and phenotypic and genotypic features of ESBL, carbapenemase, and mcr resistance genes in multidrug-resistant bacteria. Samples were inoculated on culture media, identified using standard biochemical tests, and species confirmation was performed via 16S rRNA gene amplification. Furthermore, antibiotic susceptibilities were evaluated using the Kirby-Bauer disc diffusion method. The phenotypically confirmed resistant strains were further inspected for ESBL, carbapenemases, and mcr variants using PCR. Merely 57.24% (83/145) of the samples exhibited growth. Of these, 39.70% (33/83) were identified as Klebsiella pneumoniae, 27.70% (23/83) as Escherichia coli, 10.80% (9/83) as Pseudomonas aeruginosa, 9.60% (8/83) as Staphylococcus aureus, 7.20% (6/83) as Proteus mirabilis, and 4.80% (4/83) as Staphylococcus saprophyticus. Overall, 22.54% (16/71) of the gram-negative strains were confirmed molecularly to have resistant genes. The ESBL - producers accounted for 21.74% (5/23) of E. coli, 21.21% (7/33) of K. pneumoniae, and 22.22% (2/9) of P. aeruginosa. Likewise, carbapenemase-harboring strains included 6.06% (2/33) of K. pneumoniae, 4.35% (1/23) of E. coli, and 11.11% (1/9) of P. aeruginosa. Notably, 3.03% (1/33) of K. pneumoniae, 8.70% (2/23) of E. coli, and 11.11% (1/9) of P. aeruginosa strains tested positive for the mcr-1 gene. None of the Proteus strains showed any resistant genes. The most common variants were blaSHV-11 (non-ESBL) and blaCTX-M-15 (ESBL) accounted for 28.57% (4/14) each, blaTEM-116 accounted for 14.29% (2/14), blaSHV-1, blaSHV-75, blaTEM-1 and blaOXA-1 accounted for 7.14% (1/14) each of the ESBL. Similarly, the carbapenemase variants included blaOXA-48, blaNDM-1, blaVIM-1, and blaKPC-2, each accounting for 25.0% (1/4), while 37.50% (6/16) of the strains exhibited co-existence of different gene variants. Based on our findings, it can be concluded that females, especially those in middle age, were more infected. These pathogens exhibited a wide range of ESBL, carbapenemase, and mcr-1 variants. Imipenem was suggested as the preferred medication.

Resistance reduction and cross-resistance of spinosad-resistant Rhyzopertha dominica (Coleoptera: Bostrichidae) and the association between spinosad resistance and maltase activity.

The lesser grain borer, Rhyzopertha dominica, is a serious stored-products pest mainly controlled by insecticides. Spinosad, an environmentally friendly biological insecticide with low mammalian toxicity, is considered a suitable candidate for R. dominica management. Given the structural similarity of spinosad and maltose, both containing a neutral sugar structure, it was hypothesized that maltase may hydrolyze spinosad, rendering R. dominica resistant to spinosad. In this study, multiple spinosad-resistant strains (RdSR) were used to test the hypothesis. The resistance reduction examination of a spinosad-resistant strain RdSR-1 showed a significant decrease in resistance level over 1 year with the LC50 decreasing from 2.996 to 0.392 mg kg-1 indicating an 86.92% reduction. Cross-resistance investigations using the resistant strain RdSR-2 revealed a correlation between spinosad and spinetoram, while no such cross-resistance was observed with other insecticides. The expression levels of four maltase genes were significantly higher in the resistant strain RdSR-1 than the susceptible one. Furthermore, 3,5-Dinitrosalicylic acid (DNS) assays suggested increased spinosad hydrolysis in the resistant strain RdSR-3 compared to the susceptible one. The maltase inhibitor, acarbose, was applied to susceptible R. dominica, resulting in a significant increase in mortality among individuals exposed to both acarbose and spinosad. These findings imply that acarbose can synergize the efficacy of spinosad in R. dominica. The study suggests maltase as a potential resistance mechanism in R. dominica against spinosad. This novel mechanism combined with reduction and cross-resistance results provide valuable insights for control strategy development. © 2025 Society of Chemical Industry.

AIE-Active Antibacterial Photosensitizer Disrupting Bacterial Structure: Multicenter Validation against Drug-Resistant Pathogens.

Antimicrobial resistance (AMR) has emerged as a global challenge in treating bacterial infections, creating an urgent need for broad-spectrum antimicrobial agents that can effectively combat multidrug-resistant (MDR) bacteria. Despite advancements in novel antimicrobial agents, many fail to comprehensively cover common resistant bacterial strains or undergo rigorous multi-center validation. Herein, a cationic AIE-active photosensitizers are developed, ITPM, derived from a triphenylamine-pyridine backbone to address the MDR challenge. Rigorous validation demonstrates that ITPM possesses superior fluorescence imaging capabilities and exceptional antibacterial efficacy. And its broad-spectrum activity is verified through a multi-center study involving six clinically relevant MDR strains. Additionally, resistance development studies and comparisons with advanced clinical antibiotics reveal that ITPM exhibits potent, broad-spectrum antimicrobial activity with minimal resistance development. This efficacy is attributed to its unique antibacterial mechanism involving disrupting bacterial internal structures. These findings establish ITPM as a promising candidate for broad-spectrum antimicrobial therapy, offering a potential solution to the growing crisis of AMR in clinical settings.

Characterization of Key Lipid Components in the Cell Membrane of Freeze-Drying Resistant Lacticaseibacillus paracasei Strains Using Nontargeted Lipidomics.

Lactic acid bacteria (LAB) are usually freeze-dried into powder for transportation and storage, with the bacterial membrane playing a crucial role in this process. However, different strains exhibit different levels of freeze-drying resistance in their cell membranes. In this study, Lacticaseibacillus paracasei (L. paracasei) strains 1F20, K56, and J5, demonstrating survival rates of 59.51, 25.86, and 4.05% after freeze-drying, respectively, were selected. The membrane structure and composition of these strains were subsequently analyzed. Bacterial live/dead staining results indicated that strain 1F20 maintained the highest membrane integrity after drying. Nontargeted lipidomics analysis revealed six differential lipid species that differed in membrane lipid compositions. KEGG functional enrichment analysis revealed 13 significantly different pathways, with glycerophospholipid metabolism being the most critical. This study explored the membrane composition of L. paracasei at the cellular level and identified key lipid species associated with freeze-drying resistance, providing a reference for screening highly resistant strains.

Emerging Threats: Antimicrobial Resistance in Extended-Spectrum Beta-Lactamase and Carbapenem-Resistant Escherichia coli.

Antimicrobial resistance (AMR) in Escherichia coli strains, particularly those producing Extended-Spectrum Beta-Lactamase (ESBL) and Carbapenemase (CR-Ec), represents a serious global health threat. These resistant strains have been associated with increased morbidity, mortality, and healthcare costs, as they limit the effectiveness of standard antibiotic therapies. The prevalence of ESBL- and CR-Ec-producing strains continues to rise, driven by the overuse and misuse of antibiotics in healthcare and agricultural settings, and facilitated by global interconnectedness through international travel, trade, and food distribution. This review article examines the molecular mechanisms behind ESBL and CR resistance, focusing on the key genes involved in these processes, such as blaCTX-M, blaKPC, and blaNDM, and the clinical challenges posed by these strains. Additionally, the public health impact, including the spread of infections in hospital and community environments, is highlighted. The discussion emphasizes the urgent need for improved diagnostic tools, robust surveillance systems, and innovative therapeutic strategies. Emerging treatments, including phage therapy and novel antibiotic combinations, show promise in addressing these challenges and offer potential breakthroughs in combating resistant strains. Lastly, the review calls for stronger antimicrobial stewardship and policy reforms to mitigate the spread of resistant E. coli strains and protect global public health. Effective intervention at multiple levels, from diagnostics to policy, is critical to controlling the threat posed by AMR.

Comparative Proteomics of Resistant and Susceptible Strains of Frankliniella occidentalis to Abamectin.

Western flower thrips, Frankliniella occidentalis (Thysanoptera: Thripidae) is an invasive agricultural pest with developed resistance to abamectin in some strains due to frequent treatment with the pesticide. In this study, we examined differentially expressed proteins (DEPs) between abamectin-resistant (AbaR; under abamectin selective pressure) and susceptible strains (AbaS; without abamectin selective pressure) of F. occidentalis. Proteins were isolated from second instar larvae of both strains and separated via two-dimensional polyacrylamide gel electrophoresis. Nano-flow liquid chromatography-tandem mass spectrometry identified selected protein spot features. From 70 DEPs, 43 spot features were identified: A total of 23 showed an increase in abundance, and 20 were down-regulated in response to abamectin pressure. The enzymatic and structural proteins were classified into the functional groups of macromolecular metabolisms, signaling and cellular processes, immune system, genetic information processing, and exoskeleton-related proteins. The up-regulation of exoskeleton-related proteins may contribute to forming a thicker cuticle, potentially hindering abamectin penetration, which is an interesting finding that needs further investigation. Two novel proteins, triacylglycerol lipase and cuticle protein CPF 2, were only expressed in AbaR. This work provides insights into abamectin resistance mechanisms in F. occidentalis, which will provide important information for developing insecticide resistance management approaches for this pest.

Clinical presentation with consequences and laboratory diagnosis of multi and extensive drug resistance in typhoid cases

Background: Enteric fever is among the major problem in the health care settings of developing countries like Pakistan. Unjudicial use and over the counter availability of antibiotics lead to the emergence of multi drug resistant and extensive drug-resistant strains of salmonella outbreak which demonstrate severity of disease of the disease. Our objective is to determine the clinical presentation, consequences and antibiotic susceptibility patterns of Multi Drug Resistant (MDR) typhoid and Extensive drug resistance (XDR) typhoid cases. Methods: The study was conducted in the department of Microbiology, Dow Diagnostic Reference and Research Laboratory, Dow University of Health Sciences. All laboratory proven Salmonella positive cultures samples were selected from laboratory that were either fully or partially treated, or were taking anti-Salmonella. Clinical trends along with clinical outcomes were assessed from clinical presentation. Furthermore, Demographic details were noted. Detailed history about the presenting illness with examination findings and medications were recorded. Results: A total of 333 patients had positive blood culture for enteric fever, in which maximum number of XDR cases 84% (n=281) were observed in blood cultures followed by MDR salmonella in 16 % (n=52). Meropenem and azithromycin didn’t show any resistance in our study. Conclusion: Our study has demonstrated that pediatric population is more vulnerable for developing salmonella infection. Carbapenems and azithromycin are among the last choices for the treatment of XDR cases. Analysis of our results imply stress on the implementation of preventive measures for spread of enteric fever including proper diagnosis, vaccination and good sanitation system

N-Acetyl cysteine exhibits antimicrobial and anti-virulence activity against Salmonella enterica.

Salmonella enterica is a common foodborne pathogen that causes intestinal illness varying from mild gastroenteritis to life-threatening systemic infections. The frequency of outbreaks due to multidrug-resistant Salmonella has been increased in the past few years with increasing numbers of annual deaths. Therefore, new strategies to control the spread of antimicrobial resistance are required. In this work, we found that N-acetyl cysteine (NAC) inhibits S. enterica at MIC of 3 mg ml-1 and synergistically activates the bactericidal activities of common antibiotics from three-fold for ampicillin and apramycin up to1000-fold for gentamycin. In addition, NAC inhibits the expression of virulence genes at sub-inhibitory concentrations in a dose-dependent manner. The whole-genome sequencing revealed that continuous exposure of S. enterica to NAC leads to the development of resistance; these resistant strains are attenuated for virulence. These results suggest that NAC may be a promising adjuvant to antibiotics for treating S. enterica in combination with other antibiotics.

Study of the Drug Resistance Function of Ivermectin-Resistance-Related miRNAs in Haemonchus contortus.

Haemonchus contortus has caused significant economic losses in many regions. The emergence of drug resistance has created new difficulties for the prevention and control of parasitic diseases in cattle and sheep. The mechanism of drug resistance to ivermectin in H. contortus is not clear; therefore, it is of great significance to study it. Non-coding RNAs, especially microRNAs (miRNAs), play important roles in drug resistance in some human tumors and insects. However, few studies have investigated whether miRNAs are involved in the regulation of drug resistance to ivermectin. In the early stages of this study, four miRNAs that may be involved in the regulation of ivermectin resistance in H. contortus were identified by high-throughput sequencing analysis of ivermectin-sensitive and -resistant strains of H. contortus. To verify whether these miRNAs are indeed related to ivermectin resistance in H. contortus, RNA interference (RNAi) experiments were performed on these miRNAs. The expression of candidate drug-resistance-related miRNA target genes before and after RNAi was detected by quantitative polymerase chain reaction. The resistance of the third-stage larvae (L3s) of H. contortus before and after RNAi was detected using 0.5% dimethyl sulfoxide and 100µg/mL ivermectin treatment. The locomotion behavior of the L3s of H. contortus before and after RNAi was detected by counting the frequency of head thrashes and body bending. Finally, we confirmed that miR-10,025-y, miR-5960-z, miR-27-y, and miR-276-y were involved in and regulate ivermectin resistance in H. contortus.