Aminoglycosides Gentamicin Research Articles

Molecular Properties of Virulence and Antibiotic Resistance of Pseudomonas aeruginosa Causing Clinically Critical Infections.

The increase in the number of hospital strains of hypervirulent and multidrug resistant (MDR) Pseudomonas aeruginosa is a major health problem that reduces medical treatment options and increases mortality. The molecular profiles of virulence and multidrug resistance of P. aeruginosa-associated hospital and community infections in Mexico have been poorly studied. In this study, we analyzed the different molecular profiles associated with the virulence genotypes related to multidrug resistance and the genotypes of multidrug efflux pumps (mex) in P. aeruginosa causing clinically critical infections isolated from Mexican patients with community- and hospital-acquired infections. Susceptibility to 12 antibiotics was determined using the Kirby-Bauer method. The identification of P. aeruginosa and the detection of virulence and efflux pump system genes were performed using conventional PCR. All strains isolated from patients with hospital-acquired (n = 67) and community-acquired infections (n = 57) were multidrug resistant, mainly to beta-lactams (ampicillin [96.7%], carbenicillin [98.3%], cefalotin [97.5%], and cefotaxime [87%]), quinolones (norfloxacin [78.2%]), phenicols (chloramphenicol [91.9%]), nitrofurans (nitrofurantoin [70.9%]), aminoglycosides (gentamicin [75%]), and sulfonamide/trimethoprim (96.7%). Most strains (95.5%) isolated from patients with hospital- and community-acquired infections carried the adhesion (pilA) and biofilm formation (ndvB) genes. Outer membrane proteins (oprI and oprL) were present in 100% of cases, elastases (lasA and lasB) in 100% and 98.3%, respectively, alkaline protease (apr) and alginate (algD) in 99.1% and 97.5%, respectively, and chaperone (groEL) and epoxide hydrolase (cif) in 100% and 97.5%, respectively. Overall, 99.1% of the strains isolated from patients with hospital- and community-acquired infections carried the efflux pump system genes mexB and mexY, while 98.3% of the strains carried mexF and mexZ. These findings show a wide distribution of the virulome related to the genotypic and phenotypic profiles of antibiotic resistance and the origin of the strains isolated from patients with hospital- and community-acquired infections, demonstrating that these molecular mechanisms may play an important role in high-pathogenicity infections caused by P. aeruginosa.

Metallo-β-lactamases producing Pseudomonas aeruginosa and the molecular mechanism of drug resistance variants

BackgroundMetallo-β-lactamases (MBLs) type carbapenemases are produced by pathogenic Pseudomonas spp. and exhibit carbapenemase activity. The study will look into drug resistance and the molecular mechanisms of drug-resistant Pseudomonas aeruginosa variants. MethodsA total of 74 P. aeruginosa strains were isolated from urine, pus, sputum, blood, throat swab, Foley’s catheter, and nasal swab. The isolates were screened for antibiotic susceptibility and the identified MDR strains were further tested for β-lactamase production. Multiplex PCR was used to identify the presence of mcr-1 and blaNDM-1 genes in MDR organisms. The minimum inhibitory concentration for ceftazidime and colistin was also determined, in addition to the biofilm inhibitor activity. Confocal microscopy was used to determine the production of biofilms. ResultsThe isolated P. aeruginosa strains exhibited antibiotic resistance to aminoglycosides (amikacin and gentamicin). Fifty three percent of the isolated P. aeruginosa strains produced metallo-β-lactamase and the remaining isolates were non-metallo-β-lactamase type (46.8 %) (p < 0.0001). The MIC value of β-lactamase producers against colistin ranges from 0.5 µg/mL to 6 µg/mL. The MDR bacteria exhibited mcr-1 and blaNDM−1 genes. The MDR P. aeruginosa strain treated with colistin and ceftazidime inhibited initial biofilm formation. These combination of antibiotics effectively prevented initial biofilm development than individual antibiotics (p < 0.001). ConclusionsThe current analysis detected MDR among P. aeruginosa isolates that carried drug-resistant genes.

RNA polymerase stalling-derived genome instability underlies ribosomal antibiotic efficacy and resistance evolution

Bacteria often evolve antibiotic resistance through mutagenesis. However, the processes causing the mutagenesis have not been fully resolved. Here, we find that a broad range of ribosome-targeting antibiotics cause mutations through an underexplored pathway. Focusing on the clinically important aminoglycoside gentamicin, we find that the translation inhibitor causes genome-wide premature stalling of RNA polymerase (RNAP) in a loci-dependent manner. Further analysis shows that the stalling is caused by the disruption of transcription-translation coupling. Anti-intuitively, the stalled RNAPs subsequently induce lesions to the DNA via transcription-coupled repair. While most of the bacteria are killed by genotoxicity, a small subpopulation acquires mutations via SOS-induced mutagenesis. Given that these processes are triggered shortly after antibiotic addition, resistance rapidly emerges in the population. Our work reveals a mechanism of action of ribosomal antibiotics, illustrates the importance of dissecting the complex interplay between multiple molecular processes in understanding antibiotic efficacy, and suggests new strategies for countering the development of resistance.

Antibiotic Resistance Profiles of Extended-Spectrum β-Lactamase (ESBL)- and Metallo-β-Lactamase (MBL)-Producing Klebsiella pneumoniae Isolates From Diabetic Foot Ulcers: Implications for Treatment Strategies.

Background Diabetic foot ulcers (DFUs) are prevalent complications of diabetes mellitus, often leading to severe infections and adverse clinical outcomes. Klebsiella pneumoniae, a gram-negative bacterium, has emerged as a significant causative agent in DFU infections, raising concerns due to its increasing antibiotic resistance, particularly in extended-spectrum β-lactamase (ESBL) and metallo-β-lactamase (MBL) production. Aim This study aimed to comprehensively assess the prevalence, antibiotic resistance profiles, and clinical correlates of ESBL- and MBL-producing K. pneumoniae isolates specifically derived from DFUs. Methods A cross-sectional observational study was conducted at Krishna Vishwa Vidyapeeth from January 2023 to June 2023, involving 126 patients diagnosed with DFUs. Clinical and demographic data were collected, and wound swabs underwent microbiological analysis. Phenotypic detection methods were employed to identify ESBL and MBL production, followed by standardized antibiotic susceptibility testing. Results Among the 126 isolates tested, 36 (28.6%) were identified as ESBL-producing and 21 (16.7%) as MBL-producing strains. ESBL-producing isolates exhibited high resistance rates to antibiotics such as ampicillin (92.3%), amoxicillin-acid (84.6%), and cephalosporins, including ceftriaxone (76.9%), and cefepime (73.8%). MBL-producing isolates demonstrated even broader resistance profiles, including resistance to fluoroquinolones (ciprofloxacin, 60.0%; levofloxacin, 57.1%), aminoglycosides (gentamicin, 42.9%), and carbapenems (meropenem, 38.1%; imipenem, 35.7%). Conclusion This study identifies a significant prevalence of ESBL- and MBL-producing K. pneumoniae in DFUs, showcasing high antibiotic resistance rates. Comorbidities correlate significantly with the presence of resistant isolates, necessitating treatment strategies for effective management.

Aminoglycoside antibiotics as first-line treatment of acute appendicitis and cholecystitis

We analyzed the efficacy and safety of aminoglycosides in a retrospective study of 415 patients with acute appendicitis and 277 patients with acute cholecystitis. The following variables increased the incidence of postoperative complications, defined as surgical site infection, recurrent intraabdominal infection, non-infectious post-operative complication, or death: age (p = 0.016 and 0.011), kidney disease (p = 0.019 and <0.001), and ASA Score (p < 0.001). The type of antibiotic therapy did not have a statistically significant effect on the incidence of postoperative complications in patients with acute appendicitis and cholecystitis (p = 0.561 and 0.547, respectively). A linear regression model showed a higher complication rate in patients with kidney disease (p = 0.014) and neoplasms (p = 0.013); the type of antibiotic therapy did not have a significant effect on the outcome (p = 0.765). There was no statistically significant difference in the post-treatment levels of creatinine in patients treated with aminoglycosides (gentamicin 3 mg/kg once daily) and in those who received other antibiotics (p = 0.75).

The FinO/ProQ-like protein PA2582 impacts antimicrobial resistance in Pseudomonas aeruginosa.

Bacteria employ small regulatory RNAs (sRNA) and/or RNA binding proteins (RBPs) to respond to environmental cues. In Enterobacteriaceae, the FinO-domain containing RBP ProQ associates with numerous sRNAs and mRNAs, impacts sRNA-mediated riboregulation or mRNA stability by binding to 5'- or 3'-untranslated regions as well as to internal stem loop structures. Global RNA-protein interaction studies and sequence comparisons identified a ProQ-like homolog (PA2582/ProQ Pae ) in Pseudomonas aeruginosa (Pae). To address the function of ProQ Pae , at first a comparative transcriptome analysis of the Pae strains PAO1 and PAO1ΔproQ was performed. This study revealed more than 100 differentially abundant transcripts, affecting a variety of cellular functions. Among these transcripts were pprA and pprB, encoding the PprA/PprB two component system, psrA, encoding a transcriptional activator of pprB, and oprI, encoding the outer membrane protein OprI. RNA co-purification experiments with Strep-tagged Pae ProQ protein corroborated an association of ProQ Pae with these transcripts. In accordance with the up-regulation of the psrA, pprA, and pprB genes in strain PAO1ΔproQ a phenotypic analysis revealed an increased susceptibility toward the aminoglycosides tobramycin and gentamicin in biofilms. Conversely, the observed down-regulation of the oprI gene in PAO1ΔproQ could be reconciled with a decreased susceptibility toward the synthetic cationic antimicrobial peptide GW-Q6. Taken together, these studies revealed that ProQ Pae is an RBP that impacts antimicrobial resistance in Pae.

Occurrence of Antimicrobial-Resistant Enterococcus spp. in Healthy Chickens Never Exposed to Antimicrobial Agents in Central Italy.

Enterococci are part of the natural flora of the gastrointestinal tract of mammals, including humans, birds and invertebrates. They can cause infection, mainly among hospitalized patients, as well as acquire and transfer antimicrobial resistance genes. The present study allowed the isolation of 98 Enterococcus (73.47% E. faecium, 23.47% E. faecalis, 3.06% E. avium) strains from 120-day-old healthy chickens that had never been treated with antimicrobials. Their antimicrobial resistance was evaluated by the agar disk diffusion method; high-level aminoglycoside (streptomycin and gentamicin) and vancomycin resistance were established using the microbroth dilution method. The highest percentages of resistant isolates were detected with quinupristin-dalfopristin (88.78%), rifampicin (64.29%), tetracyclines (45.92%), and enrofloxacin (41.84%). High percentages of susceptible strains were found with teicoplanin (100%), amoxicillin-clavulanic acid (97.96%), nitrofurantoin (94.90%), ampicillin (92.86%), chloramphenicol (90.82%), and linezolid (88.78%). About 60% of the strains were classified as MDR (multidrug-resistant). Moreover, PCR was carried out to investigate genes encoding for tetracyclines resistance determinants: tet(M), tet(L), tet(O), tet(K), and Int-Tn. Genes were detected in 68 (69.38%) strains: 36 were shown to be resistant with the agar disk diffusion method, while 28 were intermediate, and 2 were susceptible. The present study showed that chickens never treated with antimicrobials potentially harbor enterococci having phenotypic and genotypic characters of antimicrobial resistance.

Antibacterial Activities of the Algal Bromophenol Methylrhodomelol Against Pseudomonas aeruginosa.

Methylrhodomelol (1: ) is a bromophenol from the red alga Vertebrata lanosa that has been associated with antimicrobial properties. The aim of the current study was, therefore, to assess the antimicrobial potential of this compound in more detail against the gram-negative pathogen Pseudomonas aeruginosa. 1: exerted weak bacteriostatic activity against different strains when grown in minimal medium, whereas other phenolics were inactive. In addition, 1: (35 and 10 µg/mL) markedly enhanced the susceptibility of multidrug-resistant P. aeruginosa toward the aminoglycoside gentamicin, while it did not affect the viability of Vero kidney cells up to 100 µM. Finally, pyoverdine release was reduced in bacteria treated at sub-inhibitory concentration, but no effect on other virulence factors was observed. Transcriptome analysis of treated versus untreated P. aeruginosa indicated an interference of 1: with bacterial carbon and energy metabolism, which was corroborated by RT-qPCR and decreased ATP-levels in treated bacteria. In summary, the current study characterized the antibacterial properties of methylrhodomelol, revealed its potential as an adjuvant to standard antibiotics, and generated a hypothesis on its mode of action.

Perfil epidemiológico das otites canina e felina em um Hospital Veterinário Universitário: um estudo retrospectivo

The objective of this work was to analyze the cases of otitis in companion animals treated at the Veterinary Hospital Jeremias Pereira da Silva / Universidade Federal do Piauí (UFPI) and the profile of antimicrobial drugs used in the treatment of these infections. A retrospective cross-sectional observational epidemiological study was carried out on the assisted animals with otitis at the Veterinary Hospital Jeremias Pereira da Silva / (UFPI), during the period from January 2015 to December 2020, through access to the registration system called “Doctorvet”, evaluating the characteristics of the patients treated, the diagnosis and therapy adopted and the clinical response to these services. Mixed breed dogs (MBDs), with bilateral presentation of this disease and the presence of comorbidities were frequent occurrences in the animals treated. Antibiotic prescriptions of aminoglycosides (Gentamicin and Neomycin) were the most used, in formulations associated with other substances, such as antifungals and anti-inflammatories, with the commercial presentation Aurivet being the most prescribed and the one that received the greatest number of favorable reports. However, the use of other different therapeutic protocols was evidenced without justification for this choice. Establishing therapeutic protocols to be followed by veterinary clinicians, when treating otitis, and monitoring the success or failure of these prescriptions, will contribute to reveal much more than the epidemiological profile of the etiologic agents, but the adequate use of antimicrobial agents, controlling the increase in rates of antibiotic resistance, as well as consolidating promising therapeutic approaches for these infections.

Dynamics of antimicrobial resistance of uropathogenic isolates of Escherichia coli

Objective. To evaluate the dynamics of antimicrobial resistance of Escherichia coli isolates from the urine of patients hospitalized in medical institutions of Tashkent city from 2018 to 2021. Materials and Methods. The study included 1020 E. coli isolates from the urine of patients with clinical symptoms of urinary tract infections admitted to the reference laboratory of the Antimicrobial Resistance Research Center (ARRC) from three medical institutions in Tashkent city for the period 2018– 2021. Determination of sensitivity to 15 antimicrobial agents was carried out by disc-diffusion method in accordance with the guidelines of the European Committee for the Determination of Sensitivity to Antimicrobial Agents (EUCAST v.8-v.12, depending on the year of isolates isolation and testing). Results. A high level of resistance to aminopenicillins, including inhibitor-protected ones (88.0–91.1%), 3–4 generation cephalosporins (84.5–87.7%) and fluoroquinolones (74.2–81.8%) was detected. Carbapenems showed the highest activity among the tested antimicrobials: resistance to imipenem, meropenem and ertapenem was 0%, 0.8% and 18%, respectively. Notable increase in resistance to ampicillin and ceftazidime was found, but a consistently high level of resistance to piperacillin-tazobactam. A statistically significant increase (p &lt; 0.001) was found between 2018–2021 in resistance to the aminoglycoside antibiotics amikacin and gentamicin from 3.2% and 37.8% to 85.4% and 80.6%, respectively. Conclusions. In our study, for most antibiotic groups, the level of resistance remained relatively stable from 2018 to 2021, except for an explosive increase in the frequency of resistance to aminoglycosides, as well as a further increase in resistance to ampicillin and ceftazidime. The need for monitoring and tracking of antibiotic pathogens when choosing treatment regimens for various infections is obvious.

Synthesis, antibacterial and antimonooxidase activity of 4-(2-methyl-1,3-oxazol-5-yl)benzenesulfonamide

A new method for obtaining 4-(2-methyl-1,3-oxazol-5-yl)benzenesulfonamide an antiglaucomatous drug candidate oxazopt was developed using a diazotization reaction. A combined potentiated effect of the antimicrobial action of carbapenems (meropenem) and aminoglycosides (gentamicin) against antibiotic-resistant gram-positive bacteria Enterococcus faecium, Enterococcus faecalis and gram-negative bacteria Escherichia coli and antimonooxidase effect in vitro was revealed for this compound.

Genotypic characterization, antimicrobial susceptibility and virulence determinants of Campylobacter jejuni and Campylobacter coli isolated from pastured poultry farms.

Campylobacter is the leading bacterial pathogen that causes foodborne illnesses worldwide. Pasture farming is regarded as an important source of agricultural production for small farming communities. Consumer preference for pasture-raised animal products has increased; however, there is a paucity of information on the microbiological quality of pasture-raised poultry products. The purpose of this study was to explore genetic relatedness of thermophilic Campylobacter isolates, to assess antibiotic resistance phenotypically and genotypically, and to screen the presence of virulence determinants of Campylobacter isolates from pasture-raised poultry farms from southeastern United States. Ninety-seven Campylobacter isolates previously identified by Q7 BAX® System Real-Time PCR were genotyped by multilocus sequence typing (MLST). Campylobacter isolates were then evaluated for their phenotypic antimicrobial susceptibility against nine antimicrobial agents using Sensititre plates. Additionally, Campylobacter isolates were tested for the presence of antimicrobial resistance-associated elements. Furthermore, Campylobacter isolates were screened for the presence of 13 genes encoding putative virulence factors by PCR. These included genes involved in motility (flaA and flhA), adhesion and colonization (cadF, docC, racR, and virB11), toxin production (cdtA, cdtB, cdtC, wlaN, and ceuE) and invasion (ciaB and iamA). Among 97 Campylobacter isolates, Campylobacter jejuni (n = 79) and Campylobacter coli (n = 18) were identified. By MLST, C. jejuni isolates were assigned to seven clonal complexes. Among them, ST-353, ST-607 and ST-21 were the most common STs recognized. All C. coli (n = 18) isolates were included in CC-828. Interestingly, eight STs identified were not belonging any previous identified clonal complex. Campylobacter isolates displayed a high resistance rate against tetracycline (81.4%), while a low rate of resistance was observed against macrolides (azithromycin and erythromycin), quinolones and fluoroquinolones (nalidixic acid and ciprofloxacin), aminoglycosides (gentamicin), ketolide (telithromycin), amphenicol (florfenicol) and lincomycin (clindamycin). Thirteen isolates (13.54%) were pan-susceptible to all tested antibiotics, while nine isolates were multi-antimicrobial resistant (MAR; resist to three or more antimicrobial classes). Interestingly, there were no isolates resistant to all antimicrobial classes. Thr86Ile mutation was identified in all quinolones resistant strains. Erythromycin encoding gene (ermB) was identified in 75% of erythromycin resistant isolates. The A2075 mutation was detected in one erythromycin resistant strain, while A2074 could not be identified. The tetO gene was identified in 93.7% of tetracycline resistant isolates and six tetracycline susceptible isolates. In conclusion, the results of this study revealed that Campylobacter isolates from pasture-raised poultry farms showed the ST relatedness to Campylobacter isolates commonly associated with humans, indicating pasture-raised broiler flocks, similar to conventionally-reared broiler flocks, as a potential vector for antibiotic-resistant and pathogenic strains of thermophilic Campylobacter to humans.

Toxigenic characterization, spoilage potential, and antimicrobial susceptibility of coagulase-positive Staphylococcus species isolated from Minas Frescal cheese

This study aimed to identify coagulase-positive staphylococci (CPS) species from 21 samples of clandestine Minas Frescal cheese, investigate the potential for deterioration in psychrotrophic and mesophilic conditions, verify the toxigenic potential of Staphylococcus aureus, and determine the antimicrobial susceptibility profile of toxigenic S. aureus. Species determination was performed based on the detection of β-hemolysis in 5% ovine blood agar; fermentation of mannitol, maltose, and trehalose sugars; and production of acetoin. After species determination, DNA extraction and analysis was performed for S. aureus colonies for genes encoding staphylococcal toxins (eta, etb, tst, sea, seb, sec, sed, and see) using 2 multiplex PCR assays. Isolates identified as toxigenic S. aureus were tested for antimicrobial susceptibility to tetracycline, erythromycin, clindamycin, gentamicin, ciprofloxacin, sulfazotrim, trimethoprim, streptomycin, cefoxitin, vancomycin and enrofloxacin. Elevated CPS counts were observed with an average of >6 log cfu/g. Of the 355 isolates, 177 (49.86%) were identified as S. aureus. Staphylococcus hyicus, Staphylococcus intermedius, Staphylococcus delphini, and Staphylococcus coagulans were identified in 3 (0.84%), 2 (0.56%), 2 (0.56%), and 1 (0.28%) isolates, respectively. Of the total number of S. aureus, 25 (52.08%) were positive for the gene that encodes for toxic shock toxin (TSST-1). Another 16 (33.33%) were positive for the sea gene, and 4 isolates (8.33%) were positive for see and one isolate each was positive for seb (2.08%), sec (2.08%), and etb (2.08%) genes. All isolates demonstrated lipolytic activity under mesophilic and psychrotrophic conditions. S. intermedius and S. hyicus had the most prominent proteolytic potential. Multidrug resistance was observed in most of the potentially toxigenic isolates, with clindamycin having the lowest efficiency (40%), whereas the aminoglycosides (gentamicin and streptomycin) had the highest effectiveness demonstrating inhibition in all evaluated isolates. Methicillin-resistant S. aureus (MRSA) was detected. Minas Frescal cheeses, marketed in the north of Tocantins in the Brazilian Amazon region, do not comply with legal quality standards and pose a public health risk due to the enterotoxigenic potential of multiresistant isolates, in addition to low shelf life of the samples given the high spoilage potential of this microbiota.

L-glutamine sensitizes Gram-positive-resistant bacteria to gentamicin killing.

Because of the stubborn resistance to antibiotics, treating clinically resistant bacteria is a tricky business. Although considerable attention has been devoted to preventing and treating infections from drug-resistant bacteria, few studies are available on combining metabolites and antibiotics to combat methicillin-resistant Staphylococcus aureus (MRSA). This study found that exogenous L-glutamine potentiated aminoglycoside (gentamicin)-mediated killing efficacy in a dose- and time-dependent manner in MRSA (USA300 cell line) and other Gram-positive-resistant bacteria including MRSA 252, Listeria monocytogenes, and Corynebacterium diphtheriae. L-glutamine promoted the uptake of gentamicin through increasing the membrane permeability and was correlated with disrupted pH gradient. Furthermore, L-glutamine decreased intracellular reactive oxygen species by glutathione, which also increased USA300 sensitivity to gentamicin. We also demonstrated that combined treatment with gentamicin and L-glutamine enhanced the survival of MRSA-infected mice. In conclusion, we developed a promising therapeutic strategy for treating Gram-positive-resistant bacterial infections.IMPORTANCEMethicillin-resistant Staphylococcus aureus (MRSA) infection severely threatens human health due to high morbidity and mortality; it is urgent to develop novel strategies to tackle this problem. Metabolites belong to antibiotic adjuvants which improve the effect of antibiotics. Despite reports of L-glutamine being applied in antibiotic adjuvant for Gram-negative bacteria, how L-glutamine affects antibiotics against Gram-positive-resistant bacteria is still unclear. In this study, L-glutamine increases the antibacterial effect of gentamicin on MRSA, and it links to membrane permeability and pH gradient (ΔpH), resulting in uptake of more gentamicin. Of great interest, reduced reactive oxygen species (ROS) by glutathione was found under L-glutamine treatment; USA300 becomes sensitive again to gentamicin. This study not only offers deep understanding on ΔpH and ROS on bacterial resistance but also provides potential treatment solutions for targeting MRSA infection.

Detection and genomic characterization of a multidrug-resistant Salmonella Newport co-harbouring blaCMY-2, qnrB19 and mcr-9 from the diarrheic faeces of a foal

ObjectivesThis study reports the genomic characterization of the multidrug resistant Salmonella Newport strain 195_20 recovered from the diarrheic faeces of a foal in Brazil and co-harbouring the mcr-9, blaCMY-2 and qnrB19 antibiotic resistance genes. MethodsBacterial isolate positive for mobile colistin resistance gene (mcr-9) was submitted to antimicrobial susceptibility testing by disk diffusion and broth microdilution for colistin and polymyxin B. The isolate was submitted to whole genome sequencing by Illumina technology and Nanopore Sequencing. Conjugation assays, plasmid sizes determined by S1-PFGE and plasmid content were investigated by hybrid assembly after MinIon long reads sequencing. ResultsIsolate 195_20 was identified as sequence type ST45, resistant to penicillin and cephalosporins (ampicillin, ceftazidime, ceftriaxone and cefotaxime), aminoglycosides (streptomycin and gentamicin), phenicol (chloramphenicol), quinolones and fluoroquinolones (nalidixic acid, ciprofloxacin, and pefloxacin), folate pathway antagonists (sulfonamides and trimethoprim-sulfamethoxazole), and tetracycline. A transferable IncHI2/IncHI2A plasmid sized ca. 262kb was found to carry the mcr-9 gene in a module consisting of IS903-mcr-9-wbuC-IS26. In addition, an 174kb IncC and a 48kb IncN plasmid were also identified in the 195_20 isolate, carrying blaCMY-2 and qnrB19, respectively. ConclusionsNot surprisingly, isolate 195_20 was susceptible to polymyxins, possibly due to absence of qseBC regulatory operon. Presence of mobile colistin resistance (mcr-9), third-generation cephalosporins (blaCMY-2) and quinolone (qnrB19) resistance determinants in zoonotic pathogens from animals in close contact with humans alerts for the possible route of transmission between these different reservoirs.

Vitamin E and Silymarin Reduce Oxidative Tissue Damage during Gentamycin-Induced Nephrotoxicity.

Aminoglycoside antibiotics and gentamicin (GN), in particular, are still widely used in clinical practice. It is a well-known fact that GN causes nephrotoxicity, and redox disturbances are discussed as a factor in its side effects. Recently, a new type of cell oxidative death, named ferroptosis, was discovered; it is associated with iron accumulation in the cell, glutathione (GSH) depletion and inactivation of glutathione peroxidase-4 (GPX4), reactive oxygen species (ROS) increment with concomitant lipid peroxidation. In this regard, a possible connection between GN-induced renal damage, ferroptosis and the overall antioxidant status of the organism could be investigated. Moreover, due to its beneficial effects, GN is still one of the main choices as a therapeutic agent for several diseases, and the possible reduction of its side effects with the application of certain antioxidants will be of important clinical significance. The study was conducted with adult male white mice divided into several groups (n = 6). GN nephrotoxicity was induced by the administration of GN 100-200 mg/kg i.p. for 10 days. The control group received only saline. The other groups received either Vitamin E (400 mg/kg p.o.) or Silymarin (200 mg/kg p.o.) applied alone or together with GN for the same period. After the end of the study, the animals were sacrificed, and blood and tissue samples were taken for the assessment of biochemical parameters and antioxidant status, as well as routine and specific for GPX4 histochemistry examination. The experimental results indicate that GN-induced nephrotoxicity negatively modulates GPX4 activity and is associated with increased production of ROS and lipid peroxidation. The groups treated with antioxidants demonstrated preserved antioxidant status and better GPX4 activity. In conclusion, the inhibition of ROS production and especially the suppression of ferroptosis, could be of clinical potential and can be applied as a means of reducing the toxic effects of GN application.

Preparation and investigation of a novel antibacterial collagen-based material loaded with gentamicin following surface modification with citric acid for corneal tissue engineering

Corneal disease is an important clinical problem that affects millions of blind people and keratoplasty is currently the most successful treatment for corneal blindness. Unfortunately, there is a very high risk of bacterial infection during corneal transplantation. In this study, we proposed a novel synthetic collagen-based film for corneal therapy, and we effectively incorporated aminoglycoside gentamicin molecules onto the surface of the collagen film. We anticipate that this collagen-based substance will be antimicrobial and repair corneal tissue damage. Three steps were used to create this gentamicin-modified carboxylated collagen film, including: (i) Cross-link the collagen molecules with 1-ethyl-3- (3-dimethylaminopropyl) carbodiimide and n-hydroxysuccinimide to create a collagen (Col) film. (ii) Citric acid was used to modify the Col film's surface in order to increase the number of carboxyl groups there (ColCA). (iii) Gentamicin molecules were grafted onto the surface of ColCA film by forming amide bonds (ColCA-GM). We discovered that this ColCA-GM film has good physicochemical properties and excellent biocompatibility. Furthermore, it was demonstrated that treating collagen films with citric acid significantly improved the antibacterial properties of ColCA-GM film. The outcomes point to a variety of potential applications for this novel film in corneal tissue engineering.

A study of Alfa Feto Protein parameter in Serum and Histological Effects of Pups Liver by SEM in Pregnant Rats Exposed to Overdose of Aminoglycoside antibiotics

The study has been conducted in Animal House/Faculty of Sciences/University of Kufa between December 2022 and February 2022, fifteen female Albino Rats are used. Gentamicin is aminoglycoside antibiotics widely used during pregnancy for treatment the infections. The present study has been intended to show Alfa Feto Protein parameter in serum and the histological effects of gentamicin on pups liver by SEM in female Albino Rats. The females Rats are randomly divided into three main groups, comprising five rats for each group .The control group is given inta peritoneal injection of physiological normal saline and the second and third group are given inta peritoneal injection of gentamicin doses twenty, forty mg/kg/day respectively for 20 days from the first day to the end of experimental allocated for each female.The rats are sacrificed in 20 th (dpc) to study the Alfa Feto Protein parameter in serum and histological effects of gentamicin on pups liver. The physiological study show negative results in all study groups due to absent of malformations in pups and present histological effects in external architecture structure of pups liver compare with control groups. In conclusion; aminoglycoside gentamicin caused histological effects on pupa liver and not absent of malformations in pups due to negative results of Alfa Feto Protein parameter.

Determination of Minimum Inhibitory Concentration of Different Antibiotics against Pseudomonas aeruginosa by E- test at a Tertiary Care Hospital

Background: Antimicrobial drug resistance is a matter of worldwide concern. Different microorganisms, including bacteria, are becoming more resistant day by day. So it is of utmost importance to know the antimicrobial susceptibility pattern not only for initiation of treatment but also for prevention of drug resistance. By determining minimum inhibitory concentration (MIC) by Epsilometer-test (E-test), we can determine the exact dose of a particular drug.&#x0D; Aims: The study is aimed to determine the MIC of different antibiotics against intermediate isolates of P. aeruginosa isolated from clinically suspected patients of chronic suppurative otitis media (CSOM).&#x0D; Materials and Methods: A cross-sectional type of descriptive study was conducted in the Department of Microbiology, Rajshahi Medical College, Rajshahi, during the period of January 2019 to December 2019 to identify the causative bacteria of CSOM with their antibiotic susceptibility pattern. A total of 96 aural swabs were collected from clinically suspected cases of CSOM, irrespective of age and sex, in the ENT department of Rajshahi Medical College Hospital, Rajshahi. Isolation and identification of bacteria were made as per standard procedure, and then antimicrobial susceptibility testing was performed by the disc diffusion method. At last, E-test was performed on different antibiotics against intermediate isolates of P. aeruginosa.&#x0D; Results: Among 73 isolates, 37 showed intermediate susceptibility towards selected antibiotics such as beta-lactams (Ceftazidime, Ceftriaxone), aminoglycosides (Gentamicin), and quinolones (Ciprofloxacin) by disc diffusion method. Among 37 intermediate isolates, P. aeruginosa was 14 in number. Regarding MIC breakpoints in terms of susceptibility, out of 14 intermediate isolates of P. aeruginosa, 09(64.28%) isolates were susceptible, 03(21.43%) intermediate, and 2(14.28%) were resistant to different antibiotics by E-test.&#x0D; Conclusion: In this study, higher susceptibility of different antibiotics against intermediate isolates of P. aeruginosa was observed by E-test than the disc diffusion method.&#x0D; TAJ 2022; 36: No-1: 47-54

Antimicrobial-Resistant Escherichia coli, Enterobacter cloacae, Enterococcus faecium, and Salmonella Kentucky Harboring Aminoglycoside and Beta-Lactam Resistance Genes in Raw Meat-Based Dog Diets, USA.

The practice of feeding raw meat-based diets to dogs has grown in popularity worldwide in recent years. However, there are public health risks in handling and feeding raw meat-based dog diets (RMDDs) to dogs since there are no pathogen reduction steps to reduce the microbial load, which may include antimicrobial-resistant pathogenic bacteria. A total of 100 RMDDs from 63 suppliers were sampled, and selective media were used to isolate bacteria from the diets. Bacterial identification, antimicrobial susceptibility testing, and whole-genome sequencing (WGS) were conducted to identify antimicrobial resistance (AMR). The primary meat sources for RMDDs included in this study were poultry (37%) and beef (24%). Frozen-dry was the main method of product production (68%). In total, 52 true and opportunistic pathogens, including Enterobacterales (mainly Escherichia coli, Enterobacter cloacae) and Enterococcus faecium, were obtained from 30 RMDDs. Resistance was identified to 19 of 28 antimicrobials tested, including amoxicillin/clavulanic acid (23/52, 44%), ampicillin (19/52, 37%), cephalexin (16/52, 31%), tetracycline (7/52, 13%), marbofloxacin (7/52, 13%), and cefazolin (6/52, 12%). All 19 bacterial isolates submitted for WGS harbored at least one type of AMR gene. The identified AMR genes were found to mediate resistance to aminoglycoside (gentamicin, streptomycin, amikacin/kanamycin, gentamicin/kanamycin/tobramycin), macrolide, beta-lactam (carbapenem, cephalosporin), tetracycline, fosfomycin, quinolone, phenicol/quinolone, and sulfonamide. In conclusion, the results of this study suggest that feeding and handling RMDDs may pose a significant public health risk due to the presence of antimicrobial-resistant pathogens, and further research and intervention may be necessary to minimize these risks.