Resistance Determinants Research Articles

Exploring Molecular Drivers of PARPi Resistance in BRCA1-Deficient Ovarian Cancer: The Role of LY6E and Immunomodulation.

Approximately 50% of patients diagnosed with ovarian cancer harbor tumors with mutations in BRCA1, BRCA2, or other genes involved in homologous recombination repair (HR). The presence of homologous recombination deficiency (HRD) is an approved biomarker for poly-ADP-ribose polymerase inhibitors (PARPis) as a maintenance treatment following a positive response to initial platinum-based chemotherapy. Despite this treatment option, the development of resistance to PARPis is common among recurrent disease patients, leading to a poor prognosis. In this study, we conducted a comprehensive analysis using publicly available datasets to elucidate the molecular mechanisms driving PARPi resistance in BRCA1-deficient ovarian cancer. Our findings reveal a central role for the interferon (IFN) pathway in mediating resistance in the context of BRCA1 deficiency. Through integrative bioinformatics approaches, we identified LY6E, an interferon-stimulated gene, as a key mediator of PARPi resistance, with its expression linked to an immunosuppressive tumor microenvironment (TME) encouraging tumor progression and invasion. LY6E amplification correlates with poor prognosis and increased expression of immune-related gene signatures, which is predictive of immunotherapy response. Interestingly, LY6E expression upon PARPi treatment resistance was found to be dependent on BRCA1 status. Gene expression analysis in the Orien/cBioPortal database revealed an association between LY6E and genes involved in DNA repair, such as Rad21 and PUF60, emphasizing the interplay between DNA repair pathways and immune modulation. Moreover, PUF60, Rad21, and LY6E are located on chromosome 8q24, a locus often amplified and associated with the progression of ovarian cancer. Overall, our study provides novel insights into the molecular determinants of PARPi resistance and highlights LY6E as a promising prognostic biomarker in the management of HRD ovarian cancer. Future studies are needed to fully elucidate the molecular mechanisms underlying the role of LY6E in PARPi resistance.

Exploring AMR and virulence in Klebsiella pneumoniae isolated from humans and pet animals: A complement of phenotype by WGS-derived profiles in a One Health study in Egypt

Klebsiella pneumoniae is a ubiquitous nosocomial pathogen associated with various types of infections in hospitalized patients and different animal species. In the current study, 49 Klebsiella strains isolated from humans, dogs, and cats were investigated using NGS technology. MALDI-TOF failed to identify newly discovered K. variicola and K. quasipneumoniae isolates correctly. MLST analysis revealed different sequence types among K. pneumoniae isolates, and the most frequent STs were ST29, ST219, and ST37. Three ST23 that are generally known as hypervirulent type were identified but they lacked major discriminatory determinants for hypervirulent K. pneumoniae (hvKp). K. pneumoniae isolates showed high diversity, and several isolates from humans and animals were assigned to the same ST and were almost identical. Isolates from humans exhibited more pronounced resistance patterns compared to the animal isolates. High levels of resistance were observed for piperacillin, trimethoprim/sulfamethoxazole, and cephalosporins, and resistance to carbapenem compounds was only found in isolates of human origin. Three strains of human origin were extensively drug-resistant (XDR). A diverse range of resistance genes primarily confer resistance to beta-lactams., phenicol/quinolone, aminoglycoside, macrolide, sulfonamides, and fosfomycin were identified in silico. However, there were inconsistencies between the phenotypic characterization of isolates and the set of resistance genes detected in silico in this set of Klebsiella isolates. Further research using a larger number of isolates from various sources is necessary to fully comprehend the relationship between the presence of antimicrobial resistance determinants and phenotypic data. It is also necessary to monitor the spread of K. pneumoniae from a One Health perspective in Egypt.

Prevalence and Molecular Epidemiology of Intestinal Colonization by Multidrug-Resistant Bacteria among Hematopoietic Stem-Cell Transplantation Recipients: A Bulgarian Single-Center Study.

Background/Objectives: Intestinal colonization by multidrug-resistant (MDR) bacteria is considered one of the main risk factors for invasive infections in the hematopoietic stem-cell transplant (HSCT) setting, associated with hard-to-eradicate microorganisms. The aim of this study was to assess the rate of intestinal colonization by MDR bacteria and their microbial spectrum in a group of post-HSCT patients to study the genetic determinants of beta-lactam and glycopeptide resistance in the recovered isolates, as well as to determine the epidemiological relation between them. Methods: The intestinal colonization status of 74 patients admitted to the transplantation center of University Hospital "St. Marina"-Varna in the period January 2019 to December 2021 was investigated. Stool samples/rectal swabs were screened for third-generation cephalosporin and/or carbapenem-resistant Gram-negative bacteria, methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE), and Stenotrophomonas maltophilia. Identification and antimicrobial susceptibility testing were performed by Phoenix (BD, Sparks, MD, USA) and MALDI Biotyper sirius (Bruker, Bremen, Germany). Molecular genetic methods (PCR, DNA sequencing) were used to study the mechanisms of beta-lactam and glycopeptide resistance in the collected isolates, as well as the epidemiological relationship between them. Results: A total of 28 patients (37.8%) were detected with intestinal colonization by MDR bacteria. Forty-eight non-duplicate MDR bacteria were isolated from their stool samples. Amongst them, the Gram-negative bacteria prevailed (68.8%), dominated by ESBL-producing Escherichia coli (30.3%), and followed by carbapenem-resistant Pseudomonas sp. (24.2%). The Gram-positive bacteria were represented exclusively by Enterococcus faecium (31.2%). The main beta-lactam resistance mechanisms were associated with CTX-M and VIM production. VanA was detected in all vancomycin-resistant enterococci. A clonal relationship was observed among Enterobacter cloacae complex and among E. faecium isolates. Conclusions: To the best of our knowledge, this is the first Bulgarian study that presents detailed information about the prevalence, resistance genetic determinants, and molecular epidemiology of MDR gut-colonizing bacteria in HSCT patients.

AmpC induction by imipenem in Pseudomonas aeruginosa occurs in the absence of OprD and impacts imipenem/relebactam susceptibility.

In the United States, carbapenem resistance in Pseudomonas aeruginosa is linked to the regulation of chromosomal resistance determinants, AmpC and OprD. The β-lactamase AmpC requires overexpression and genetic modifications to be capable of inhibiting imipenem activity. The outer membrane porin OprD can be downregulated or undergo genetic modifications that strongly correlate with imipenem non-susceptibility. Co-administration of imipenem and the β-lactamase inhibitor, relebactam, can lower imipenem minimal inhibitory concentrations and restore susceptibility. However, it is not understood how this occurs in P. aeruginosa isolates that do not overproduce AmpC or produce a functional OprD for imipenem entry. Therefore, we investigated whether imipenem could enter P. aeruginosa in the absence of OprD and whether any of the chromosomal β-lactamases (AmpC, OXA-50, and PIB-1) contributed to imipenem and/or imipenem/relebactam non-susceptibility. This investigation evaluated 17 imipenem non-susceptible clinical isolates and three laboratory strains of PAO1, two of which were porin transposon mutants for either oprD or opdP. Expression of OXA-50 and PIB-1 RNA was similar to PAO1. However, all 20 isolates exhibited blaampC induction under sublethal exposure to imipenem. This occurred in the absence of detectable OprD protein in 18 isolates. Collectively, our data identify that (i) OprD was not the only channel required for imipenem entry and (ii) imipenem susceptibility can be restored by imipenem/relebactam due to the interaction between relebactam and blaampC overexpression due to imipenem induction.IMPORTANCEInfections caused by Pseudomonas aeruginosa are associated with high mortality and worsened clinical outcomes. The carbapenem, imipenem, has been combined with the β-lactamase inhibitor relebactam to treat carbapenem-resistant P. aeruginosa. Downregulation of the outer membrane porin, OprD is the major mechanism of imipenem resistance; however, relebactam inhibits the chromosomally encoded AmpC β-lactamase. We investigated how relebactam was able to reduce P. aeruginosa imipenem minimal inhibitory concentrations (MICs) in isolates in which OprD was downregulated. Our data show that imipenem is capable of entering the cell in the absence of OprD and capable of inducing the AmpC β-lactamase. The induction of AmpC provides a substrate for relebactam, impacting the imipenem MIC. The data presented support the use of an alternative porin(s) for entry of imipenem. This study provides the basis for further investigation into modifications of imipenem or similar molecules that would increase the affinity for other porins in isolates resistant to imipenem.

The determination of abrasion resistance and adhesion of varnishes with various ratios of graphene additive on different wood

The determination of abrasion resistance and adhesion of varnishes with various ratios of graphene additive on different wood

Carbapenem-Resistant Enterobacterales in the Western Balkans: Addressing Gaps in European AMR Surveillance Map.

In the context of global efforts to combat antimicrobial resistance (AMR), the importance of comprehensive AMR data is more crucial than ever. AMR surveillance networks, such as the European Antimicrobial Resistance Surveillance Network (EARS-Net) and the Central Asian and European Surveillance of Antimicrobial Resistance (CAESAR), support member states in obtaining high-quality AMR data. Nevertheless, data gaps persist in some countries, including those in the Western Balkans (WBs), a region with high AMR rates. This review analyzed existing research on carbapenem-resistant Enterobacterales (CRE) to better understand the AMR landscape in the WB countries. The most prevalent CRE was Klebsiella pneumoniae, followed by Escherichia coli, Enterobacter cloacae, and Proteus mirabilis, with sporadic cases of Morganella morganii, Providencia spp., Klebsiella oxytoca, and Citrobacter sedlakii. Carbapenemase production was identified as the most common mechanism of carbapenem resistance, but other resistance mechanisms were not investigated. An increasing trend in carbapenem resistance has been observed over the last decade, alongside a shift in carbapenemase epidemiology from the NDM type in 2013-2014 to the OXA-48 type in recent years. Few studies have applied whole-genome sequencing for CRE analysis, which has demonstrated the spread of resistance determinants across different niches and over time, emphasizing the importance of molecular-based research. The overall low number of studies in the WB countries can be attributed to limited resources, highlighting the need for enhanced support in education, training, technology, and equipment to improve data collection and evaluation.

Poultry manure and vegetables as vehicles for antimicrobial resistance determinants distribution in some Farms in Delta State, Nigeria

Poultry manure and vegetables as vehicles for antimicrobial resistance determinants distribution in some Farms in Delta State, Nigeria

Genomic characterization of an uncommon Delftia acidovorans isolate obtained from aBulgarian immunocompetent outpatient diagnosed with bronchitis.

Delftia acidovorans is an aerobic, non-fermenting Gram-negative bacterium (NFGNB), found in soil, water and hospital environments. It is rarely clinically significant, most commonly affecting hospitalized or immunocompromised patients. The present study aimed to explore the genomic characteristics of a Bulgarian clinical D. acidovorans isolate (designated Dac759) in comparison to all strains of this species with available genomes in the NCBI Genome database (n = 34). Dac759 was obtained in 2021 from the sputum of a 65-year-old female immunocompetent outpatient with bronchitis. Species identification using MALDI-TOF mass spectrometry, antimicrobial susceptibility testing, whole-genome sequencing (WGS), and phylogenomic analysis were performed. The isolate demonstrated high-level resistance to colistin (16 mg L-1); resistance to gentamicin; reduced susceptibility to piperacillin, piperacillin-tazobactam, ceftazidime, cefepime, ciprofloxacin, and levofloxacin; and susceptibility to imipenem, meropenem, amikacin, and tobramycin. The observed genome size (6.43 Mb) and GC content (66.76%) were comparable with the accessible data from sequenced D. acidovorans genomes. A limited number of resistance determinants were identified in the assembled genome as follows: blaOXA-459, emrE, oqxB, and mexCD-oprJ. The phylogenomic analysis indicated a high heterogenicity of the included D. acidovorans genomes. In conclusion, to the best of our knowledge, this is the first documented case of a clinically relevant D. acidovorans isolate in Bulgaria. Unlike the majority of reports in the literature, Dac759 affected a patient with no malignancies or other preexisting comorbidities. With this in mind, its genome sequence is a valuable resource for the fundamental study of uncommon bacterial pathogens of public health importance.

Multidrug-resistant tuberculosis clusters and transmission in Taiwan: a population-based cohort study.

Multidrug-resistant tuberculosis (MDR-TB) remains a challenge in the TB program of Taiwan, where 0.5% of new cases and 2.1% of previously treated cases were resistant to at least rifampin (RIF) and isoniazid (INH). Since >80% of our MDR-TB are new cases, genotyping of MDR Mycobacterium tuberculosis is implemented to facilitate contact investigation, cluster identification, and outbreak delineation. This is a population-based retrospective cohort study analyzing MDR-TB cases from 2019 to 2022. Whole genome sequencing (WGS) was performed using the Illumina MiSeq and analyzed using the TB Profiler. A single nucleotide polymorphism (SNP) threshold of ≤ 12 and phylogenetic methods were used to identify putative transmission clusters. An outbreak was confirmed using genomic data and epidemiologic links. Of the 297 MDR-TB cases, 246 (82.8%), 45 (15.2%), and 6 (2.0%) were simple MDR, extensively drug-resistant tuberculosis (pre-XDR-TB) and extensively drug-resistant tuberculosis (XDR-TB), respectively. The sublineage 2.2 modern Beijing was the predominant (48.8%) MDR-TB strain in Taiwan. Phylogenetic analysis identified 25.3% isolates in 20 clusters, with cluster sizes ranging from 2 to 13 isolates. Nevertheless, only 2 clusters, one household and one community, were confirmed as outbreaks. In this study, we found that males had a higher risk of MDR-TB transmission compared to females, and those infected with the sublineage 2.1-proto-Beijing genotype isolates were at a higher risk of transmission. Furthermore, 161 (54.2%) isolates harbored compensatory mutations in the rpoC and non-rifampicin resistant determinant region (non-RRDR) of the rpoB gene. MDR-TB strains containing rpoB S450L and other compensatory mutations concurrently were significantly associated with clusters, especially the proto-Beijing genotype strains with the compensatory mutation rpoC E750D or the modern Beijing genotype strains with rpoC D485Y/rpoC E1140D. Routine and continuous surveillance using WGS-based analysis is recommended to warn of risks and delineate transmission clusters of MDR-TB. We proposed the use of compensatory mutations as epidemiological markers of M. tuberculosis to interrupt putative MDR-TB transmission.

Detection of KPC-3 producing Escherichia coli ST410 in Volos, Greece.

Escherichia coli A382 was isolated in July 2024 from a positive blood culture obtained from the central venous catheter of a male patient undergoing chemotherapy at the Hospital of Volos, Thessaly, Greece. Whole-genome sequencing analysis revealed that the isolate A382 is E. coli belonging to the ST410 high-risk clone, which co-harbors the blaKPC-3 and blaSHV-182 genes on an IncX3 plasmid. It also harbors blaTEM-1 and has five replicons, as follows: IncX3, IncQ1, CoIRNAI, IncF1A, and IncFIB. Complete genome analysis revealed that E. coli A382 isolate carries a range of virulence factors (iutA, iucC, fimH, fdeC, yehA, yehD, yehC, yehB, cgs, ahha, ccI, hlyE, papC, irp2, fyuA, lpfA, and nlpl) and many other non-beta-lactam resistance determinants, including dfrA14 and sul2, but it is susceptible to aminoglycosides, nitrofurantoin, tigecycline, colistin and ceftazidime-avibactam. In conclusion in this study, we describe the phenotypic and genome characteristics of an extensively drug-resistant E. coli ST410.

Co-Occurrence of Two Plasmids Encoding Transferable blaNDM-1 and tet(Y) Genes in Carbapenem-Resistant Acinetobacter bereziniae.

Acinetobacter bereziniae has emerged as a significant human pathogen, acquiring multiple antibiotic resistance genes, including carbapenemases. This study focuses on characterizing the plasmids harboring the blaNDM-1 and tet(Y) genes in two carbapenem-resistant A. bereziniae isolates (UCO-553 and UCO-554) obtained in Chile during the COVID-19 pandemic. Methods: Antibiotic susceptibility testing was conducted on UCO-553 and UCO-554. Both isolates underwent whole-genome sequencing to ascertain their sequence type (ST), core genome multilocus sequence-typing (cgMLST) profile, antibiotic resistance genes, plasmids, and mobile genetic elements. Conjugation experiments were performed for both isolates. Results: Both isolates exhibited broad resistance, including resistance to carbapenems, third-generation cephalosporins, fluoroquinolones, tetracycline, cotrimoxazole, and aminoglycosides. Both isolates belong to sequence type STPAS1761, with a difference of 17 out of 2984 alleles. Each isolate carried a 47,274 bp plasmid with blaNDM-1 and aph(3')-VI genes and two highly similar plasmids: a 35,184 bp plasmid with tet(Y), sul2, aph(6)-Id, and aph(3″)-Ib genes, and a 6078 bp plasmid containing the ant(2″)-Ia gene. Quinolone-resistance mutations were identified in the gyrA and parC genes of both isolates. Importantly, blaNDM-1 was located within a Tn125 transposon, and tet(Y) was embedded in a Tn5393 transposon. Conjugation experiments successfully transferred blaNDM-1 and tet(Y) into the A. baumannii ATCC 19606 strain, indicating the potential for horizontal gene transfer. Conclusions: This study highlights the critical role of plasmids in disseminating resistance genes in A. bereziniae and underscores the need for the continued genomic surveillance of this emerging pathogen. The findings emphasize the importance of monitoring A. bereziniae for its potential to cause difficult-to-treat infections and its capacity to spread resistance determinants against clinically significant antibiotics.

First detection of VEB-1 extended-spectrum β-lactamase-producing Escherichia coli clinical isolate in Japan.

ESBLs are plasmid-mediated enzymes that confer resistance to clinically significant antimicrobial agents, such as broad-spectrum cephalosporins. Recently, the rapid spread of CTX-M-type ESBL-producing E. coli has become a global issue, including in Japan, where ESBL production in human pathogenic E. coli, such as the ExPEC and UPEC lineages, which typically harbor several virulence genes, is a severe public health concern. To date, VEB (Vietnamese extended-spectrum β-lactamase) producers have been found only in hospital wastewater and rivers in Japan. Thus, we describe the first detection of a very rare human-derived blaVEB-1 gene in the E. coli B2-ST95 pandemic clonal lineage that is highly associated with ExPEC and UPEC in a Japanese clinical setting. Furthermore, we characterized the genomic features of plasmids harboring the class 1 integron-borne blaVEB-1. Our findings highlight the significance of closely monitoring ESBL-producing E. coli isolates to prevent the potential dissemination of this resistance determinant in Japan.

Oxidative Stress and Age-Related Tumors.

Oxidative stress is the result of the imbalance between reactive oxygen and nitrogen species (RONS), which are produced by several endogenous and exogenous processes, and antioxidant defenses consisting of exogenous and endogenous molecules that protect biological systems from free radical toxicity. Oxidative stress is a major factor in the aging process, contributing to the accumulation of cellular damage over time. Oxidative damage to cellular biomolecules, leads to DNA alterations, lipid peroxidation, protein oxidation, and mitochondrial dysfunction resulting in cellular senescence, immune system and tissue dysfunctions, and increased susceptibility to age-related pathologies, such as inflammatory disorders, cardiovascular and neurodegenerative diseases, diabetes, and cancer. Oxidative stress-driven DNA damage and mutations, or methylation and histone modification, which alter gene expression, are key determinants of tumor initiation, angiogenesis, metastasis, and therapy resistance. Accumulation of genetic and epigenetic damage, to which oxidative stress contributes, eventually leads to unrestrained cell proliferation, the inhibition of cell differentiation, and the evasion of cell death, providing favorable conditions for tumorigenesis. Colorectal, breast, lung, prostate, and skin cancers are the most frequent aging-associated malignancies, and oxidative stress is implicated in their pathogenesis and biological behavior. Our aim is to shed light on the molecular and cellular mechanisms that link oxidative stress, aging, and cancers, highlighting the impact of both RONS and antioxidants, provided by diet and exercise, on cellular senescence, immunity, and development of an antitumor response. The dual role of ROS as physiological regulators of cell signaling responsible for cell damage and diseases, as well as its use for anti-tumor therapeutic purposes, will also be discussed. Managing oxidative stress is crucial for promoting healthy aging and reducing the risk of age-related tumors.

In vitro efficacy of aquaculture antimicrobials and genetic determinants of resistance in bacterial isolates from tropical aquaculture disease outbreaks.

Understanding the efficacy of antimicrobials against pathogens from clinical samples is critical for their responsible use. The manuscript presents in vitro efficacy and antimicrobial resistance (AMR) genes in seven species of fish pathogens from the disease outbreaks of Indian aquaculture against oxytetracycline, florfenicol, oxolinic acid, and enrofloxacin. In vitro efficacy was evaluated by minimum inhibitory concentration and minimum bactericidal concentration. The gene-specific PCR screened AMR genes against quinolones (qnrA, qnrB, and qnrS) and tetracyclines (tetM, tetS, tetA, tetC, tetB, tetD, tetE, tetH, tetJ, tetG, and tetY). The results showed that Aeromonas veronii (45%) showed the maximum resistance phenotype, followed by Streptococcus agalactiae (40%), Photobacterium damselae (15%), Vibrio parahaemolyticus (10%), and Vibrio vulnificus (5%). There was no resistance among Vibrio harveyi and Vibrio alginolyticus against the tested antimicrobials. The positive association between tetA, tetB, tetC, tetM, or a combination of these genes to oxytetracycline resistance and qnrS to quinolone resistance indicated their potential in surveillance studies. The prevalence of resistance phenotypes (16.43%) and evaluated AMR genes (2.65%) against aquaculture antimicrobials was low. The resistance phenotype pattern abundance was 0.143. All the isolates showed susceptibility to florfenicol. The results help with the appropriate drug selection against each species in aquaculture practices.

Non-canonical IL-22 receptor signaling remodels the mucosal barrier during fungal immunosurveillance.

Mucosal barrier integrity is vital for homeostasis with commensal organisms while preventing pathogen invasion. We unexpectedly found that fungal-induced immunosurveillance enhances resistance to fungal outgrowth and tissue invasion by remodeling the oral mucosal epithelial barrier in mouse models of adult and neonatal Candida albicans colonization. Epithelial subset expansion and tissue remodeling were dependent on interleukin-22 (IL-22) and signal transducer and activator of transcription 3 (STAT3) signaling, through a non-canonical receptor complex composed of glycoprotein 130 (gp130) coupled with IL-22RA1 and IL-10RB. Immunosurveillance-induced epithelial remodeling was restricted to the oral mucosa, whereas barrier architecture was reset once fungal-specific immunity developed. Collectively, these findings identify fungal-induced transient mucosal remodeling as a critical determinant of resistance to mucosal fungal infection during early stages of microbial colonization.

Molecular genetic characteristics of Streptococcus pneumoniae serogroups 15 and 11 representatives circulating in Russia and their relationship with global genetic lineages

Aim of the study. Genetic analysis of Streptococcus pneumoniae serogroups 15 and 11 circulating in Russia according to the following parameters: serotype affiliation; clonal complex (CC); presence of resistance and virulence determinants; relatedness to genetic lineages circulating in the world, and justification of inclusion of the actual serotypes of serogroups 15 and 11 in the future conjugate vaccine composition. Materials and methods. The study included whole genome data of S. pneumoniae serogroups 11 and 15. Results. Genomes of serogroup 15 strains from Russia are represented mainly by serotypes 15B and 15C, the majority of which belong to CC-1025 and CC-1262. CC-1025 is characterized by a more frequent association with invasive diseases. Representatives of CC-1025 and CC-1262 contain virulence determinants unique to these genetic lineages within the studied population of serogroup 15: oligopeptide transporters, fructose-specific PTS system, unique hydrolase variants, additional iron ion transporters, the gene of zinc metalloprotease ZmpC (activating human MMP9). The genomes of serogroup 11 are represented mainly by serotype 11A, the majority belong to CC-62 and CC-1012. The virulence determinants unique to CC-62 (within the studied serogroup 11) include bacteriocins, components of oligopeptide transport, flavin reductase-like protein (adhesin, also protects bacteria from oxidative stress), fucose processing operon, PsaA (adhesin, also a component of the ATP-binding cassette transporter that imports manganese ions). Conclusion. In the Russian Federation, serogroups 15 and 11 are the most common non-vaccine serogroups. No antimicrobial resistance determinants have been identified in the genomes of representatives of these serogroups. For each of the genetic lineages prevalent in Russia and associated with serogroups 15 and 11, unique virulence determinants within the studied serogroup have been identified, which may contribute to the success of these lineages. It is advisable to include serotypes 15B and 11A in vaccines promising for the Russian Federation.

Characteristics of the Klebsiella Pneumoniae Strain Isolated from a Positive Blood Culture of a Premature Newborn Baby According to the Results of Whole Genome Sequencing

Relevance. K. pneumoniae is a common nosocomial pathogen in pediatric hospitals, often characterized by the presence of a wide range of virulence factors and genetic determinants of antibiotic resistance. Аim. To analyze the results obtained during wholegenome sequencing of a Klebsiella pneumoniae strain isolated from a positive blood culture of a premature newborn. Materials and methods. An ESBL-producing strain of K. pneumoniae isolated from a positive blood culture of a newborn premature infant. Sequencing was performed on the MiSeq platform (Illumina). Analysis of DNA nucleotide sequences of the complete genome of K. pneumoniae was carried out using the website of the Center for Genomic Epidemiology. The search for genetic determinants of antibiotic resistance and virulence was carried out using online services. Results and its discussion. The resulting nucleotide sequence was 5,414,099 bp in length, and the proportion of GC nitrogenous bases was 57.3%. The isolated strain belonged to the sequence type ST3559, had 4 genes encoding the synthesis of enzymes that hydrolyze antibacterial drugs from the beta-lactam group, 2 genes providing resistance to quinolones/fluoroquinolones, 1 resistance gene each to trimethoprim, chloramphenicol, fosfomycin and aminoglycoside antibiotics. Most of the virulence factor genes identified in the studied strain ensure the recognition and absorption of iron ions necessary for the competitive functioning of the bacterial cell. K. pneumoniae possesses the acrA efflux pump gene and its regulators, as well as 4 prophage particles and 1 CRISPCas IE system. Conclusions. Whole-genome sequencing of the K. pneumoniae strain isolated from a positive blood culture of a premature newborn allows us to characterize in detail the causative agent of a generalized infection and detect a wide range of genetic determinants of virulence factors and antibiotic resistance. The ESBL-producing strain of K. pneumoniae, as the etiological agent of neonatal sepsis, was characterized by the presence of virulence genes, multidrug resistance, both due to genes encoding enzymes that hydrolyze antibiotics, and due to the presence of efflux pumps and their regulators. The use of the results of traditional cultural research methods together with high-throughput sequencing data is a promising area of scientific research and has a reserve of practical application in the field of clinical medicine, genetics of microorganisms, molecular epidemiology at the local and global levels

Emergence of multidrug resistant mobile colistin resistance (mcr) carrying Aeromonas spp. isolated from retail foods in Mymensingh district, Bangladesh

The emergence of plasmid-mediated mobile colistin resistance (mar) in bacteria under Enterobacteriaceae, and aeromonads isolated from foods has been reported in many parts of the world. So far, we know there is no report of mcr carrying Aeromonas spp. Isolated from retail foods in Bangladesh. Therefore, this study was carried out to determine the prevalence of mcr carrying Aeromonas spp. isolated from retail foods (meat, milk, and fish) in Mymensingh district and their characterization for antimicrobial resistance patterns. The prevalence of mcr-1 gene carrying Aeromonas spp. was 30 % (15/50) in chickens, 23 % (8/35) in fish, and 10 % (2/20) in milk. No other tested mcr gene variants (mcr-2 to 4) were detected. The minimum inhibitory concentration (MIC) for colistin was determined to be 80% (12/15) and 75% (6/8) of the mcr-1 gene carrying Aeromonas spp. isolated from chicken and fish, respectively, had an MIC of 8-16 µg/ml whereas 100% (2/2) of the isolate from milk showed a MIC of 4–8 µg/ml. Most of the mcr-1 gene-carrying isolates from chicken meats, fish, and milk were resistant to oxytetracycline, and ampicillin (80%–100%). Apart from multidrug resistant (MDR), extensive MDR was detected in mcr-1 gene-carrying Aeromonas spp., irrespective of the sample’s origin. Overall, these data suggested that the mcr-1 gene-carrying Aeromonas spp. in retail foods could be a potential reservoir for antimicrobial resistance determinants. To the best of our knowledge, this is the first report of the mcr gene carrying Aeromonas spp. isolated from retail foods such as chicken meat, fish, and milk in Bangladesh. Res. Agric. Livest. Fish. Vol. 11, No. 2, August 2024: 115-124

Characterization of blaOXA-232 carrying carbapenem-resistant Klebsiella pneumoniae (CRKP) & their expression profiles under selective carbapenem pressure: An in-depth study from India.

Background & objectives OXA-232 is a five amino acid substitution variant of OXA-48 and is reported in carbapenem-resistant Klebsiella pneumoniae (CRKP), which is associated with nosocomial infections among immunocompromised patients in the intensive care unit. This study aimed to characterise blaOXA-232 in CRKP of clinical origin and investigate its transcriptional response against sub-inhibitory levels of carbapenems. Methods CRKP was isolated from blood (pathogens) and stool cultures (colonisers) of neonates and was characterized for blaOXA-232. Co-existing resistance determinants were investigated in blaOXA-232 positive isolates, followed by horizontal gene transferability assay and PCR-based replicon typing (PBRT). Cloning of blaOXA-232 was performed, and expression of blaOXA-232 in the isolates and their clones under sub-inhibitory concentrations of carbapenems was checked via RT-PCR. Mobile genetic elements associated with blaOXA-232 were investigated, followed by DNA fingerprinting through enterobacterial repetitive intergenic consensus (ERIC) PCR. Results blaOXA-232 with co-carriage of extended-spectrum beta-lactamases (ESBLs), sulphonamides and quinolones were identified in seven CRPK isolates recovered from blood samples of neonates. Transformation and cloning of blaOXA-232 was successful. The sub-inhibitory concentration of carbapenems induces elevated expression of this resistant determinant. ISEcp1 was associated with blaOXA-232 in the upstream region within two haplotypes of CRKP isolates of clinical origin. Interpretation & conclusions Selective carbapenem pressure resulted in higher expression of this gene, which could account for treatment failure. With frequent reports of occurrence among clinical isolates, monitoring and further investigation of this novel variant are necessary to understand its transmission dynamics and to thwart its further dissemination.

Phenotypic and genotypic determination of resistance to common disinfectants among strains of Acinetobacter baumannii producing and non-producing biofilm isolated from Iran

BackgroundNosocomial infections are a global problem in hospitals all around the world. It is considered a major health problem, especially in developing countries. The increase in the patient’s stay in hospitals has increased the mortality rate, and consequently, the costs drastically increase. The main purpose of using disinfectants in the hospital environment is to reduce the risk of nosocomial infections. Ethylene diamine tetra acetic acid (EDTA) causes lysis and increases susceptibility to antimicrobial agents in the planktonic form of bacteria. This substance affects the permeability of the outer membrane of bacteria. It also prevents the formation of biofilms by bacteria.Materials and methodsIn the current study, 120 isolates of Acinetobacter baumannii (A. baumannii) were confirmed by phenotypic and genotypic methods. Antibiogram was performed and then the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of isolates against 5% sodium hypochlorite, ethanol %70, sayasept-HP 2%, chlorhexidine 2%, dettol 4/8% were evaluated. In addition, the disinfectant effect was re-evaluated with the mixture of EDTA solution. All isolates were examined for biofilm presence by crystal violet staining method in triplicates and repeated three times for each strain. Also for all isolates detection of efflux pump genes (Qac-E, qacE-Δ1, SUG-E) by PCR technique was done.ResultsAntibiogram results of A. baumannii showed that 6.7% were Multi-drug-resistant (MDR), and 89.2% were Extensively drug-resistant (XDR) isolates. The highest effect of disinfectants was related to 5% sodium hypochlorite, and the least effect was 70% ethanol. EDTA increases the efficacy of selected disinfectants significantly. The highest prevalence of the efflux pump genes was related to SUG-E (95%) and Qac-E (91.7%), and, the qacE-Δ1 gene with 12.5%. The biofilm production rate was 91.3% among all isolates.ConclusionThe best and safest way to disinfect hospital floors and surfaces is to choose the right disinfectants, and learn how to use them properly. In this study, a mixture of disinfectants and EDTA had a significant effect on bactericidal activity. it was found that improper use of disinfectants, especially the use of sub-inhibitory dilutions, increases the resistance of bacteria to disinfectants.