Cefoxitin inhibits the formation of biofilm involved in antimicrobial resistance MDR Escherichia coli. - Related Documents




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575201.0000Cefoxitin inhibits the formation of biofilm involved in antimicrobial resistance MDR Escherichia coli. The study investigates the relationship between biofilm formation and antibiotic resistance in Escherichia coli (E. coli) isolated from calves. Using biochemical and molecular methods, we identified the isolates and assessed their biofilm-forming ability through an improved crystal violet staining method. The minimum inhibitory concentrations (MICs) of 18 antibiotics against the isolates were determined using the broth microdilution method. The impact of cefoxitin on biofilm formation was analyzed using laser scanning confocal microscopy (LSCM). Additionally, qRT-PCR was employed to evaluate the expression levels of biofilm-related genes (luxS, motA, fliA, pfs, and csgD) in response to varying cefoxitin concentrations. Results indicated a significant correlation between antimicrobial resistance (AMR) and biofilm formation ability. Cefoxitin effectively reduced biofilm formation of multidrug-resistant E. coli isolates at 1/2 and 1 MIC, with enhanced inhibition at higher concentrations. The QS-related genes luxS, pfs, motA, and fliA were downregulated, leading to decreased csgD expression. At 1/2 MIC, csgD expression was significantly reduced. In conclusion, cefoxitin inhibits biofilm formation in multidrug-resistant E. coli by down-regulating key genes, offering a potential strategy to mitigate resistance and control infections in calves caused by biofilm-positive E. coli isolates.202540122078
575810.9997RND pump inhibition: in-silico and in-vitro study by Eugenol on clinical strain of E. coli and P. aeruginosa. Multidrug-resistant (MDR) gram-negative bacteria pose significant challenges to the public health. Various factors are involved in the development and spread of MDR strains, including the overuse and misuse of antibiotics, the lack of new antibiotics being developed, and etc. Efflux pump is one of the most important factors in the emergence of antibiotic resistance in bacteria. Aiming at the introduction of novel plant antibiotic, we investigated the effect of eugenol on the MexA and AcrA efflux pumps in Pseudomonas aeruginosa (P. aeruginosa) and Escherichia coli (E. coli). Molecular docking was performed using PachDock Server 1.3. The effect of eugenol on bacteria was determined by disk diffusion, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). A cartwheel test was also performed to evaluate efflux pump inhibition. Finally, the expression of the MexA and AcrA genes was examined by real-time PCR. The results of molecular docking showed that eugenol interacted with MexA and AcrA pumps at - 29.28 and - 28.59 Kcal.mol(-1), respectively. The results of the antibiogram test indicated that the antibiotic resistance of the treated bacteria decreased significantly (p < 0.05). The results of the cartwheel test suggested the inhibition of efflux pump activity in P. aeruginosa and E. coli. Analysis of the genes by real-time PCR demonstrated that the expression of MexA and AcrA genes was significantly reduced, compared to untreated bacteria (p < 0.001). The findings suggest, among other things, that eugenol may make P. aeruginosa and E. coli more sensitive to antibiotics and that it could be used as an inhibitor to prevent bacteria from becoming resistant to antibiotics.202337587975
575920.9996The Relationship between Antibiotic Susceptibility and pH in the Case of Uropathogenic Bacteria. Urinary tract infections (UTIs) are common bacterial infections caused mainly by enteric bacteria. Numerous virulence factors assist bacteria in the colonization of the bladder. Bacterial efflux pumps also contribute to bacterial communication and to biofilm formation. In this study, the phenotypic and genetic antibiotic resistance of clinical UTI pathogens such as Escherichia coli, Klebsiella pneumoniae, and Proteus mirabilis were determined by disk diffusion method and polymerase chain reaction (PCR). Following this, different classes of antibiotics were evaluated for their antibacterial activity at pH 5, 6, 7 and 8 by a microdilution method. Gentamicin (GEN) was the most potent antibacterial agent against E. coli strains. The effect of GEN on the relative expression of marR and sdiA genes was evaluated by quantitative PCR. The slightly acidic pH (pH 6) and GEN treatment induced the upregulation of marR antibiotic resistance and sdiA QS activator genes in both E. coli strains. Consequently, bacteria had become more susceptible to GEN. It can be concluded that antibiotic activity is pH dependent and so the artificial manipulation of urinary pH can contribute to a more effective therapy of multidrug resistant bacterial infections.202134943643
576030.9996Downregulation of Klebsiella pneumoniae RND efflux pump genes following indole signal produced by Escherichia coli. BACKGROUND: More than a century has passed since it was discovered that many bacteria produce indole, but research into the actual biological roles of this molecule is just now beginning. The influence of indole on bacterial virulence was extensively investigated in indole-producing bacteria like Escherichia coli. To gain a deeper comprehension of its functional role, this study investigated how indole at concentrations of 0.5-1.0 mM found in the supernatant of Escherichia coli stationary phase culture was able to alter the virulence of non-indole-producing bacteria, such as Pseudomonas aeruginosa, Proteus mirabilis, and Klebsiella pneumoniae, which are naturally exposed to indole in mixed infections with Escherichia coli. RESULTS: Biofilm formation, antimicrobial susceptibility, and efflux pump activity were the three phenotypic tests that were assessed. Indole was found to influence antibiotic susceptibly of Pseudomonas aeruginosa, Proteus mirabilis and Klebsiella pneumoniae to ciprofloxacin, imipenem, ceftriaxone, ceftazidime, and amikacin through significant reduction in MIC with fold change ranged from 4 to 16. Biofilm production was partially abrogated in both 32/45 Pseudomonas aeruginosa and all eight Proteus mirabilis, while induced biofilm production was observed in 30/40 Klebsiella pneumoniae. Moreover, acrAB and oqxAB, which encode four genes responsible for resistance-nodulation-division multidrug efflux pumps in five isolates of Klebsiella pneumoniae were investigated genotypically using quantitative real-time (qRT)-PCR. This revealed that all four genes exhibited reduced expression indicated by 2^-ΔΔCT < 1 in indole-treated isolates compared to control group. CONCLUSION: The outcomes of qRT-PCR investigation of efflux pump expression have established a novel clear correlation of the molecular mechanism that lies beneath the influence of indole on bacterial antibiotic tolerance. This research provides novel perspectives on the various mechanisms and diverse biological functions of indole signaling and how it impacts the pathogenicity of non-indole-producing bacteria.202439182027
575640.9995Chlorogenic acid attenuates tet (X)-mediated doxycycline resistance of Riemerella anatipestifer. INTRODUCTION: The increasing resistance of R. anatipestifer has posed a significant threat to the poultry industry in recent years. The tet gene is the primary determinant of tetracycline resistance in numerous bacteria, and the enzyme modification gene tet(X) is predominantly detected in tetracycline-resistant R. anatipestifer strains. METHODS: In this study, we evaluated the susceptibility of both the standard strain and clinical isolates of R. anatipestifer to doxycycline. And the expression levels of tet(X), tet(A), and tet(O) genes were detected. To assess drug susceptibility, shuttle plasmids were constructed to transfer the tet(X) gene into the standard strain of R. anatipestifer followed by treatment with chlorogenic acid. RESULTS AND DISCUSSION: The results revealed that the minimum inhibitory concentration of doxycycline for the standard strain was 0.25μg/mL, whereas it exceeded 8μg/mL for the clinical isolates. Furthermore, there was a significant upregulation observed in expression levels of tet(X), tet(A), and tet(O) genes among induced strains. Interestingly, when transferring the tet(X) gene into the standard strain, its sensitivity to doxycycline decreased; however, MIC values for chlorogenic acid remained consistent between both standard and drug-resistant strains of R. anatipestifer. Moreover, we made a surprising discovery that screening passage with chlorogenic acid resulted in increased sensitivity of R. anatipestifer to doxycycline. Further analysis demonstrated a reversal in expression trends among three differentially expressed genes within induced drug resistance group after intervention with chlorogenic acid. The main objective behind this study is to investigate both killing effect exerted by chlorogenic acid on drug-resistant R. anatipestifer as well as its regulatory impact on drug resistance genes. This will provide novel insights and theoretical basis towards development of chlorogenic acid as a promising drug for treatment and control of drug resistance in R. anatipestifer.202438764851
575150.9995The use of eugenol in combination with cefotaxime and ciprofloxacin to combat ESBL-producing quinolone-resistant pathogenic Enterobacteriaceae. AIM: Emergence of extended-spectrum beta-lactamase (ESBL) producing with quinolone-resistant (QR) pathogenic Enterobacteriaceae augmented the need to establish therapeutic options against them. Present study aimed towards determination of synergistic combination of eugenol (EG) with cefotaxime (CTX) and ciprofloxacin (CIP) to combat against this resistance and potentiation of antibacterial drugs by EG against these bacteria. METHODS AND RESULTS: Synergistic interaction between EG and CTX/CIP (FICI: 0·08-0·5) were observed among ESBL-QR bacteria using checkerboard assay. Approximately, 2- to 1024-fold minimum inhibitory concentration value reduction and 17- to 165 030-fold dose reduction index strongly suggested synergistic interaction between EG and antibiotics. Cell viability assay showed reduction in log(10) CFU per ml from 16·6 to 3·1 at synergistic concentration. Scanning electron microscopy further proved disruptive effect of EG on cell architecture. Eugenol and/or its combination also altered genes' expressions that imparted antibiotic resistance by ~1·6 to ~1226 folds. CONCLUSIONS: Reduced doses of antibiotics, bacterial morphological alterations, efflux pump down regulation, porin over expression and beta-lactamase gene inhibition of ESBL-QR bacteria by EG alone or in combination with CTX/CIP might have reversed antibiotic resistance profile of ESBL-QR bacteria. SIGNIFICANCE AND IMPACT OF THE STUDY: This study provided a molecular insight into action of EG and/with CTX and CIP, which might have potentiated antibiotic's activity against ESBL-QR bacteria.202032502298
576860.9995The resistance mechanism of Escherichia coli induced by ampicillin in laboratory. BACKGROUND: Multi-drug-resistant Escherichia coli poses a great threat to human health, especially resistant to ampicillin (AMP), but the mechanism of drug resistance is not very clear. PURPOSE: To understand the mechanism of resistance of E. coli to beta-lactam antibiotics by inducing drug resistance of sensitive bacteria in laboratory. METHODS: Clinical sensitive E. coli strain was induced into resistance strain by 1/2 minimum inhibitive concentration (MIC) induced trails of AMP. The drug resistance spectrum was measured by modified K-B susceptibility test. Whole-genome sequencing analysis was used to analyze primary sensitive strain, and resequencing was used to analyze induced strains. Protein tertiary structure encoded by the gene containing single nucleotide polymorphism (SNP) was analyzed by bioinformatics. RESULTS: After 315 hrs induced, the MIC value of E. coli 15743 reached to 256 µg/mL, 64 times higher than that of the sensitive bacteria. During the induction process, the bacterial resistance process is divided into two stages. The rate of drug resistance occurs rapidly before reaching the critical concentration of 32 µg/mL, and then the resistance rate slows down. Sequencing of the genome of resistant strain showed that E. coli 15743 drug-resistant strain with the MIC values of 32 and 256 µg/mL contained four and eight non-synonymous SNPs, respectively. These non-synonymous SNPs were distributed in the genes of frdD, ftsI, acrB, OmpD, marR, VgrG, and envZ. CONCLUSION: These studies will improve our understanding of the molecular mechanism of AMP resistance of E. coli, and may provide the basis for prevention and control of multi-drug-resistant bacteria and generation of new antibiotics to treat E. coli infection.201931571941
473870.9994Detection and evaluation of susceptibility to antibiotics in non-hydrogen sulfide-producing antibiotic-resistant soil microbe: Pseudomonas guariconensis. Antimicrobial resistance in bacteria is a global threat that can make antibacterial treatments ineffective. One well-known method of antibiotic resistance and a common defensive mechanism in many harmful bacteria is the synthesis of endogenous hydrogen sulfide (H(2)S) in bacteria. In this study, soil bacteria were screened using the lead acetate agar test and the triple sugar iron test to determine that they were non-endogenous H(2)S producers. This was further validated by full genome analysis of the identified organism against the gene sequences of H(2)S-producing genes. Antibacterial resistance of the bacteria was phenotypically analyzed using the Kirby-Bauer disk diffusion method. Then, the effect of exogenous H(2)S on the antibiotic-resistant bacteria was checked in sodium sulfide, leading to antibiotic re-sensitization.202538767682
565980.9994Pseudomonas aeruginosa clinical isolates in Egypt: phenotypic, genotypic, and antibiofilm assessment of Pluronic F-127. BACKGROUND: Virulence factors play an important role in developing bacterial resistance leading to the increased severity of Pseudomonas aeruginosa infections. Several genes encoding for virulence factors is coordinated by the quorum sensing (QS) system. In the present study, the prevalence of virulence genes, particularly those involved in controlling biofilm formation, and their correlation with antibiotic resistance patterns was investigated. The ability of the pathogens to form biofilm and the impact of Pluronic F-127 as a potential biofilm inhibitor was assessed. RESULTS: A total of 118 P. aeruginosa clinical isolates were collected. The highest resistance rates were observed against ceftazidime (94%), while colistin was the most effective followed by polymyxin B with sensitivity rate 72% and 59%, respectively. Out of 118 isolates: 111 (94%) were biofilm producers, 24.6% of them were strong. The QS genes; lasR and rhlR, were detected in 85% and 89% of the isolates, respectively, toxA gene in 95% and ampC gene in 69% of the isolates. Pluronic F-127 was confirmed as a biofilm inhibitor in lowest concentration used 1.25 mg/ml which inhibits 78% of strong biofilm forming isolates and has better effect on detachment of established biofilm by 90% of biofilm forming isolates. CONCLUSION: The ability of bacteria to form biofilms contributes greatly to the development of antibiotic resistance, which leads to the occurrence of persistent and chronic bacterial illnesses. Many isolates exhibited moderate to strong biofilm forming ability, which showed a high resistance pattern. The results demonstrated that Pluronic F-127 has a promising level of biofilm inhibition and detachment in most isolates. It has a chance to serve as a substitute means for combating biofilm formation.202540281406
576590.9994Expression of Pseudomonas aeruginosa Antibiotic Resistance Genes Varies Greatly during Infections in Cystic Fibrosis Patients. The lungs of individuals with cystic fibrosis (CF) become chronically infected with Pseudomonas aeruginosa that is difficult to eradicate by antibiotic treatment. Two key P. aeruginosa antibiotic resistance mechanisms are the AmpC β-lactamase that degrades β-lactam antibiotics and MexXYOprM, a three-protein efflux pump that expels aminoglycoside antibiotics from the bacterial cells. Levels of antibiotic resistance gene expression are likely to be a key factor in antibiotic resistance but have not been determined during infection. The aims of this research were to investigate the expression of the ampC and mexX genes during infection in patients with CF and in bacteria isolated from the same patients and grown under laboratory conditions. P. aeruginosa isolates from 36 CF patients were grown in laboratory culture and gene expression measured by reverse transcription-quantitative PCR (RT-qPCR). The expression of ampC varied over 20,000-fold and that of mexX over 2,000-fold between isolates. The median expression levels of both genes were increased by the presence of subinhibitory concentrations of antibiotics. To measure P. aeruginosa gene expression during infection, we carried out RT-qPCR using RNA extracted from fresh sputum samples obtained from 31 patients. The expression of ampC varied over 4,000-fold, while mexX expression varied over 100-fold, between patients. Despite these wide variations, median levels of expression of ampC in bacteria in sputum were similar to those in laboratory-grown bacteria. The expression of mexX was higher in sputum than in laboratory-grown bacteria. Overall, our data demonstrate that genes that contribute to antibiotic resistance can be highly expressed in patients, but there is extensive isolate-to-isolate and patient-to-patient variation.201830201819
6284100.9994Acinetobacter baumannii quorum-sensing signalling molecule induces the expression of drug-resistance genes. Quorum-sensing signalling molecules such as N‑acyl homoserine lactones (AHLs) enable certain Gram‑negative bacteria to respond to environmental changes through behaviours, such as biofilm formation and flagellar movement. The present study aimed to identify Acinetobacter baumannii AHLs and assess their influence on antibiotic resistance. A clinical isolate of A. baumannii strain S (AbS) was collected from the wound of a burn patient and high‑performance liquid chromatography and tandem quadrupole or quadrupole time‑of‑flight high‑resolution mass spectrometry was used to identify AbS AHLs. Antibiotic sensitivity was assessed in an AHL‑deficient AbS mutant (AbS‑M), and the expression of drug-resistance genes in the presence of meropenem in AbS, AbS‑M and AbS‑M treated with the AHL N-3-hydroxy-dodecanoyl-homoserine lactone (N‑3‑OH‑C12‑HSL). AbS‑M was more sensitive to meropenem and piperacillin than wild‑type AbS, but resistance was restored by supplementation with N‑3‑OH‑C12‑HSL. In addition, meropenem‑treated AbS‑M expressed lower levels of the drug‑resistance genes oxacillinase 51, AmpC, AdeA and AdeB; treatment with N‑3‑OH‑C12‑HSL also restored the expression of these genes. Overall, the results of the present study indicate that N‑3‑OH‑C12‑HSL may be involved in regulating the expression of drug‑resistance genes in A. baumannii. Therefore, this quorum‑sensing signalling molecule may be an important target for treating multidrug‑resistant A. baumannii infections.201728487993
5639110.9994Disinfectant and antibiotic resistance of lactic acid bacteria isolated from the food industry. Quaternary ammonium compounds (QACs) are widely used as disinfectant in medical and food environments. There is a growing concern about the increasing incidence of disinfectant-resistant microorganisms from food. Disinfectant-resistant lactic acid bacteria (LAB) may survive disinfection and cause spoilage problems. Moreover, resistant LAB may potentially act as a reservoir for resistance genes. A total number of 320 LAB from food industry and meat were screened for resistance to the QAC benzalkonium chloride (BC). Out of 320 strains, five strains (1.5%) were considered to be resistant and 56 (17.5%) were tolerant to BC. The resistant strains were isolated from food processing equipment after disinfection. The resistant, tolerant, and some sensitive control bacteria were examined for susceptibility to 18 different antibiotics, disinfectants, and dyes using disc agar diffusion test and microdilution method. Little systematic cross-resistance between BC and any of the antimicrobial agents tested were detected except for gentamycin and chlorhexidine. A BC-tolerant strain was much easier to adapt to higher levels of BC as compared to a BC-sensitive strain. No known gram-positive QAC resistance genes (qacA/B, qacC, qacG, and qacH) were detected in the BC-resistant strains. Identification to species level of the BC-resistant isolates was carried out by comparative analysis of 16S-rDNA sequencing. In conclusion, resistance to BC is not frequent in LAB isolated from food and food environments. Resistance may occur after exposure to BC. The BC resistant isolates showed no cross-resistance with other antimicrobial compounds, except for gentamycin and chlorhexidine. Nevertheless, BC-resistant LAB may be isolated after disinfection and may contribute to the dissemination of resistance.200111310806
5766120.9994Ceftazidime resistance in Pseudomonas aeruginosa is multigenic and complex. Pseudomonas aeruginosa causes a wide range of severe infections. Ceftazidime, a cephalosporin, is a key antibiotic for treating infections but a significant proportion of isolates are ceftazidime-resistant. The aim of this research was to identify mutations that contribute to resistance, and to quantify the impacts of individual mutations and mutation combinations. Thirty-five mutants with reduced susceptibility to ceftazidime were evolved from two antibiotic-sensitive P. aeruginosa reference strains PAO1 and PA14. Mutations were identified by whole genome sequencing. The evolved mutants tolerated ceftazidime at concentrations between 4 and 1000 times that of the parental bacteria, with most mutants being ceftazidime resistant (minimum inhibitory concentration [MIC] ≥ 32 mg/L). Many mutants were also resistant to meropenem, a carbapenem antibiotic. Twenty-eight genes were mutated in multiple mutants, with dacB and mpl being the most frequently mutated. Mutations in six key genes were engineered into the genome of strain PAO1 individually and in combinations. A dacB mutation by itself increased the ceftazidime MIC by 16-fold although the mutant bacteria remained ceftazidime sensitive (MIC < 32 mg/L). Mutations in ampC, mexR, nalC or nalD increased the MIC by 2- to 4-fold. The MIC of a dacB mutant was increased when combined with a mutation in ampC, rendering the bacteria resistant, whereas other mutation combinations did not increase the MIC above those of single mutants. To determine the clinical relevance of mutations identified through experimental evolution, 173 ceftazidime-resistant and 166 sensitive clinical isolates were analysed for the presence of sequence variants that likely alter function of resistance-associated genes. dacB and ampC sequence variants occur most frequently in both resistant and sensitive clinical isolates. Our findings quantify the individual and combinatorial effects of mutations in different genes on ceftazidime susceptibility and demonstrate that the genetic basis of ceftazidime resistance is complex and multifactorial.202337192202
2868130.9994Detection and Analysis of Drug and Disinfectant Resistance Genes in the Sewage of a Center for Disease Control and Prevention. PURPOSE: Sewage is a significant reservoir for drug and disinfectant resistance genes and a medium for dissemination. This study aimed to evaluate the presence of drug and disinfectant resistance genes in the sewage of a Center for Disease Control and Prevention (CDC) and to assess the risks of their dissemination. METHODS: Sewage from a CDC in Hangzhou was collected, filtered, and enriched, and its microorganisms were cultured. The isolated bacteria were identified, and the minimum inhibitory concentration (MIC) was determined. The drug and disinfectant resistance genes in the sewage and bacteria were detected through polymerase chain reaction amplification. RESULTS: Three kinds of bacteria were isolated from the sewage sample. The MIC for Sphingomonas and Staphylococcus xylosus against chlorine-containing disinfectants was 250 mg/L, whereas the MIC for Bacillus firmus was 500 mg/L. The β-lactam resistance gene TEM and the disinfectant resistance gene qacA were positive in the bacteria, whereas the β-lactam resistance genes TEM, SHV, and VIM-1, the tetracycline resistance gene tetM, the aminoglycoside resistance genes aac(6')/aph(2') and aph3'-III, and the disinfectant resistance genes qacA, qacE, and qacEΔ1 were positive in the sewage. CONCLUSION: Drug and disinfectant resistance genes were found in the sewage of a CDC and were associated with bacteria. Thus, optimizing the monitoring and treatment of sewage is crucial.202540303605
5763140.9994Development of in vitro resistance to fluoroquinolones in Pseudomonas aeruginosa. Fluoroquinolone resistance in Pseudomonas aeruginosa typically arises through site-specific mutations and overexpression of efflux pumps. In this study, we investigated the dynamics of different resistance mechanisms in P. aeruginosa populations that have evolved under fluoroquinolone pressure, as well as the interactions between these mechanisms in evolutionary trajectories. Bacteria of strain ATCC27853 were selected under different concentrations of ciprofloxacin and levofloxacin for six parallel lineages, followed by amplification of four target genes in the quinolone-resistance determining region (QRDR) and Sanger sequencing to identify the mutations. The expression of four efflux pump proteins was evaluated by real-time polymerase chain reaction using the relative quantitation method, with the ATCC27853 strain used as a control. We found that ciprofloxacin killed P. aeruginosa sooner than did levofloxacin. Further, we identified five different mutations in three subunits of QRDRs, with gyrA as the main mutated gene associated with conferring fluoroquinolone resistance. Additionally, we found a larger number of mutations appearing at 2 mg/L and 4 mg/L of ciprofloxacin and levofloxacin, respectively. Moreover, we identified the main efflux pump being expressed as MexCD-OprJ, with initial overexpression observed at 0.25 mg/L and 0.5 mg/L of ciprofloxacin and levofloxacin, respectively. These results demonstrated gyrA(83) mutation and MexCD-OprJ overexpression as the primary mechanism conferring ciprofloxacin and levofloxacin resistance in P. aeruginosa. In addition, we also show that ciprofloxacin exhibited a stronger ability to kill the bacteria while potentially rendering it more susceptible to resistance.202032758289
5770150.9994Prevalence of silver resistance genes in bacteria isolated from human and horse wounds. The aim of this study was to investigate the prevalence of silver resistance genes in 172 bacterial strains which had been isolated from both human and equine wounds. PCR screening for 8 currently named genes in 3 silver resistance transcriptional units, silE, silRS and silP, silCBA and silF was performed on total DNA extracted from all clinical isolates. Plasmids were isolated from sil-positive strains to determine if the genes were present on the chromosome. MICs and zone of inhibition assays were utilised to examine phenotypic resistance to silver nitrate and ionic silver. Evidence of silver resistance genes was demonstrated in six strains of Enterobacter cloacae, an organism rarely implicated as a primary pathogen in chronic wounds. MIC data showed that all strains were inhibited at silver nitrate concentrations > or =5mg/L. When tested against a silver-containing absorbent wound dressing all strains showed inhibition of growth after 24h. In MIC and zone of inhibition studies, inhibition was evident but reduced in strains which contained sil genes. Although sil genes were found in six of the wound isolates studied, the genes were consistently associated with a non-pathogenic bacterium. Furthermore, investigation of phenotypic resistance in sil-positive isolates showed that silver continued to be effective.200919362435
4745160.9994Determination of Antimicrobial Resistance and the Impact of Imipenem + Cilastatin Synergy with Tetracycline in Pseudomonas aeruginosa Isolates from Sepsis. Pseudomonas aeruginosa is among the most ubiquitous bacteria in the natural world, exhibiting metabolic and physiological versatility, which makes it highly adaptable. Imipenem + cilastatin and tetracycline are antibiotic combinations commonly used to treat infections caused by P. aeruginosa, including serious infections such as sepsis. In the context of bacterial infections, biofilm, formed by bacterial cells surrounded by extracellular substances forming a matrix, plays a pivotal role in the resistance of P. aeruginosa to antibiotics. This study aimed to characterize a representative panel of P. aeruginosa isolates from septicemias, assessing their susceptibility to various antibiotics, specifically, imipenem + cilastatin and tetracycline, and the impact of these treatments on biofilm formation. Results from antibiotic susceptibility tests revealed sensitivity in most isolates to six antibiotics, with four showing near or equal to 100% sensitivity. However, resistance was observed in some antibiotics, albeit at minimal levels. Notably, tetracycline showed a 100% resistance phenotype, while imipenem + cilastatin predominantly displayed an intermediate phenotype (85.72%), with some resistance (38.1%). Microdilution susceptibility testing identified effective combinations against different isolates. Regarding biofilm formation, P. aeruginosa demonstrated the ability to produce biofilms. The staining of microtiter plates confirmed that specific concentrations of imipenem + cilastatin and tetracycline could inhibit biofilm production. A significant proportion of isolates exhibited resistance to aminoglycoside antibiotics because of the presence of modifying genes (aac(3)-II and aac(3)-III), reducing their effectiveness. This study also explored various resistance genes, unveiling diverse resistance mechanisms among P. aeruginosa isolates. Several virulence genes were detected, including the las quorum-sensing system genes (lasI and lasR) in a significant proportion of isolates, contributing to virulence factor activation. However, genes related to the type IV pili (T4P) system (pilB and pilA) were found in limited isolates. In conclusion, this comprehensive study sheds light on the intricate dynamics of P. aeruginosa, a remarkably adaptable bacterium with a widespread presence in the natural world. Our findings provide valuable insights into the ongoing battle against P. aeruginosa infections, highlighting the need for tailored antibiotic therapies and innovative approaches to combat biofilm-related resistance.202338004699
4767170.9994The impact of probiotic cell-free metabolites in MDR Pseudomonas aeruginosa: antibacterial properties and effect on antibiotic resistance genes expression. There is a significant demand for novel antibacterial agents against multidrug-resistant (MDR) gram-negative bacteria. Recently, probiotics have been noted for their antibacterial properties against various pathogens. This study aimed to investigate the effects of probiotic cell-free supernatants on MDR Pseudomonas aeruginosa. Clinical isolates demonstrating the highest degree of antibiotic resistance were chosen, and the antibacterial effect of probiotic metabolites was evaluated using an agar-well diffusion assay. In addition, the effect of probiotics on the expression of resistance genes was evaluated using real-time PCR. The CFS was assessed using GC-MS to determine the antibacterial compounds. The supernatants inhibited the growth of the isolates (P < 0.0001); however, there was no noticeable difference in the effectiveness of the probiotics. In addition, the supernatants decreased the expression levels of mexD, mexB, mexF, and ampC, and an increase in oprD was observed in some groups. After the assessment of Lactobacillus acidophilus by GC-MS, antibacterial compounds, such as acetamide, nonadecane, 9-methyl, and tetradecane, were determined. Our findings showed that probiotic metabolites can effectively inhibit the growth of MDR P. aeruginosa. Gene expression analysis also revealed that the mechanism of antibacterial action was most likely related to the regulation of efflux pumps.202337742315
6286180.9994The mRNA expression of ompF, invA and invE was associated with the ciprofloxacin-resistance in Salmonella. Salmonella developed drug-resistance under durative antibiotic pressures pressure. The widespread prevalence of Salmonella has been associated with not only drug-resistance but also pathogenicity. Outer membrane porin proteins (OMPs) are critical for the drug resistance of bacteria. Virulence genes in Salmonella pathogenicity islands (SPIs) play key roles in the virulence of bacteria. In this study, we analyzed the expression levels of three critical genes in ciprofloxacin-resistant strains and ciprofloxacin-susceptible strains of Salmonella, including outer membrane porin protein F (ompF), virulence genes invA and invE. In the clinical ciprofloxacin-resistant strains of Salmonella, the expression level of ompF was decreased. Meanwhile, the expression levels of invA and invE were decreased except for only one strain, indicating generally decreased virulence. These results were also verified with ciprofloxacin-induced resistant strains. Thus, it was informative for understanding the drug-resistance in Salmonella. Monitoring drug-resistance and virulence relevant genes would be significant in the prevention and control of salmonellosis.202032535789
2340190.9994Binary CuO\CoO nanoparticles inhibit biofilm formation and reduce the expression of papC and fimH genes in multidrug-resistant Klebsiella oxytoca. BACKGROUND AND AIM: Binary copper-cobalt oxide nanoparticles (CuO\CoO NPs) are modern kinds of antimicrobials, which may get a lot of interest in clinical application. This study aimed to detect the effect of the binary CuO\CoO NPs on the expression of papC and fimH genes in multidrug-resistant (MDR) isolates of Klebsiella oxytoca to reduce medication time and improve outcomes. METHODS: Ten isolates of K. oxytoca were collected and identified by different conventional tests besides PCR. Antibiotic sensitivity and biofilm-forming ability were carried out. The harboring of papC and fimH genes was also detected. The effect of binary CuO\CoO nanoparticles on the expression of papC and fimH genes was investigated. RESULTS: Bacterial resistance against cefotaxime and gentamicin was the highest (100%), while the lowest percentage of resistance was to amikacin (30%). Nine of the ten bacterial isolates had the ability to form a biofilm with different capacities. MIC for binary CuO\CoO NPs was 2.5 µg/mL. Gene expression of papC and fimH was 8.5- and 9-fold lower using the NPs. CONCLUSION: Binary CuO\CoO NPs have a potential therapeutic effect against infections triggered by MDR K. oxytoca strains due to the NPs-related downregulation ability on the virulence genes of K. oxytoca.202337269387