Journal of global antimicrobial resistance最新文献

Objectives: The rise of multidrug-resistant (MDR) Klebsiella pneumoniae is a significant public health threat. Klebsiella quasipneumoniae is often misidentified as K. pneumoniae, and its genetic and virulence traits remain underexplored. This study characterizes the genomic and phenotypic features of a K. quasipneumoniae subsp. similipneumoniae strain (KP24) .

Methods: Antibiotic susceptibility was tested using microbroth dilution assay. Virulence was evaluated through serum killing assay and Galleria mellonella infection model. Whole genome sequencing (WGS) and bioinformatics analysis determined sequence typing, resistance profiles, and plasmid types. Conjugation assays assessed plasmid transferability, while phylogenetic analysis explored genetic relationships.

Results: KP24 exhibited an MDR phenotype, including resistance to carbapenems, ceftazidime/avibactam, and tigecycline. KP24 showed significantly higher serum survival and G. mellonella lethality than ATCC700603, though it was less virulent than the hypervirulent strain NUTH-K2044. WGS identified KP24 as ST1859 and KL35, harboring the aerobactin virulence gene cluster (iucABCDiutA) and multiple resistance genes, including tmexCD2-toprJ2, bla_KPC-2, bla_OXA-10, bla_IMP-4, and qnrS1. Notably, the tmexCD2-toprJ2 and bla_KPC-2 genes were located on the same plasmid (pKP24-1) , an uncommon co-existence. Conjugation assays confirmed the independent transferability of pKP24-1 to Escherichia coli J53. Phylogenetic analysis revealed that ST1859 forms a distinct monoclade with low genetic diversity, closely related to ST334, suggesting regional expansion and potential global dissemination.

Conclusions: KP24 represents a hypovirulent yet multidrug-resistant strain of K. quasipneumoniae subsp. similipneumoniae, with a concerning combination of virulence and resistance determinants. The co-location of tmexCD2-toprJ2 and bla_KPC-2 on a transferable plasmid highlights the potential for horizontal gene transfer of critical resistance mechanisms.

Objectives: Carbapenems are considered to be the last resort to the serious infections caused by multidrug-resistant (MDR) Gram-negative bacteria. The emergence of carbapenem-resistant Enterobacteriaceae has posed serious threat to human health. However, carbapenem resistance is rarely reported in E. fergusonii. In this study, an NDM-5 producing E. fergusonii strain EFSXRJ10 was isolated from chicken in China.

Methods: The minimal inhibitory concentrations (MICs) were determined using broth microdilution-based antimicrobial susceptibility testing. The complete genome sequence of the NDM-positive isolate was obtained through Illumina NovaSeq and Oxford Nanopore GridION sequencing platforms, followed by hybrid assembly with Unicycler. In the plasmid conjugation assay, the sodium azide-resistant E. coli strain J53 was employed as the recipient.

Results: Strain EFSXRJ10 was resistant to ampicillin, amoxycillin-Clavulanic acid, gentamicin, spectinomycin, tetracycline, florfenicol, sulfafurazole, cefotaxime, ceftazidime, apramycin and meropenem. The bla_NDM-5 gene was located on the IncHI2 plasmid. This plasmid can be transferred by conjugation at a frequency of (4.78 ± 0.67) × 10^-5. The bla_NDM-5-carrying plasmid which harboring 14 antibiotic resistance genes belonged to IncHI2/ST3 type and exhibited high similarity to other bla_NDM-5-carrying IncHI2 plasmids deposited in GenBank. The genetic structure surrounding bla_NDM-5 was organized as "IS3000-ΔISAba125-IS5-ΔISAba125-bla_NDM-5-ble_MBL-trpF-dsbD-IS26-∆umuD-∆ISKox3-∆IS3000".

Conclusions: This is the first report on the characterization of bla_NDM-5-bearing IncHI2 plasmid in E. fergusonii. Surveillance and control measures should be implemented to arrest the transmission of bla_NDM-5 from food animals.

Objectives: Across recent decades the increasing prevalence of multi-drug resistant KPC-carrying K. pneumoniae (KPC-Kp) has become a worldwide public concern. Herein, we characterized a ceftazidime/avibactam (CAZ/AVI), meropenem/vaborbactam (MER-VAB) and imipenem/relebactam (IMI-REL) resistant KPC-Kp strain isolated from a critically ill transplanted patient.

Methods: Antimicrobial susceptibility test and whole-genome sequencing (WGS) were conducted to characterize the strain at the phenotypic and the genotypic levels. Genomic DNA was sequenced using the Illumina platform. Bioinformatic analyses were used to investigate the genome sequences both for resistance and virulence features, and for characterization of plasmids.

Results: The phenotypic characterization revealed that the KPC-Kp isolate was highly resistant to a wide range of antibiotics, including all the beta-lactam/beta lactamase inhibitor combinations, such as CAZ/AVI, MER-VAB, IMI-REL, and cefiderocol (FDC). WGS analysis showed that the isolate, belonging to the rare lineage ST661, contained several resistance and virulence genes. Among the resistance genes, we identified a new KPC variant, inside the mobile genetic element Tn4401, KPC-245, characterized by an insertion of 9 aminoacids (RAPNKDDYT) at position 263 and an aminoacidic change E274D of the protein sequence, compared to KPC-3. Interestingly, the presence of mutations only in bla_KPC gene, and not in other beta-lactamases coding genes, strongly points KPC-245 role in beta-lactam/beta-lactamase inhibitor combinations and FDC resistance.

Conclusions: In our study, by using WGS analysis on a clinical isolate, we identified a new bla_KPC variant inside the Tn4401 transposon. Our results confirm the important role of the continuous surveillance of MDR K. pneumoniae in the clinical context.

Objectives: The purpose of this study was to analyze the genome of the multidrug-resistant Citrobacter freundii strain CAPA023, which was obtained from diseased Arapaima gigas fry. The study focused on determining mobile genetic elements and genetic factors that contribute to antibiotic resistance and pathogenicity.

Methods: Genomic DNA was sequenced using Illumina NovaSeq (2 × 150 bp) and assembled de novo using Shovill v1.1.0. Resistance genes, virulence factors, plasmids, and mobile elements were identified using ResFinder, CARD, PlasmidFinder, MobileFinder, PathogenFinder, and VFDB.

Results: The 5,059,550 bp draft genome (60 contigs, 51.5% GC) revealed resistance genes for various antibiotic classes, efflux pumps, IncFIB(K) and Col440I plasmids, insertion sequences, and multiple virulence genes.

Conclusion: Considering that this bacterium was found in diseased fish, it is possible that C. freundii plays an important role in the spread of virulence factors and antibiotic resistance in aquaculture environments. This highlights the importance of genomic surveillance in Amazonian aquaculture.

Objectives: ;Antimicrobial stewardship programs (ASP) aim to improve the quality of medical prescribing and contain antimicrobial resistance (AMR). There is little information on the implementation of ASP in hospitals in Mexico. This study aimed to characterize ASP in a sample of hospitals in Mexico and to identify the facilitators and barriers perceived in their implementation, including the COVID-19 pandemic.

Methods: ;A self-assessment electronic survey was adapted from the CDC and WHO ASP's core elements, considering ASP organization, structure, education, guidelines, interventions, surveillance, monitoring, and reporting processes. The survey was addressed to ASP team leaders in a sample of public and private hospitals carrying out regular antimicrobial stewardship activities in Mexico in 2021 and 2022.

Results: ;Fifty hospitals participated: 32 (64%) public and 18 (36%) private. Fifty-two percent of hospitals had an official ASP document, 12% allocated protected time for ASP professionals, and 34% had an annual plan. Most hospitals had an ASP committee (68%); only 14% allocated funding. Most interventions were restrictive (68%). 61% percent of hospitals prepared cumulative antibiograms periodically, 54% monitored antimicrobial consumption (DDD/DOT), 44% monitored adherence to guidelines, and 24% monitored the implementation of interventions. The main barriers identified were work overload, insufficient human resources, and hospital reconversion due to COVID-19 (particularly in public hospitals), while the support of hospital authorities was the most important facilitator.

Conclusions: ;This diagnosis provides a baseline for strengthening ASP implementation in the country's hospitals. National and institutional policies should prioritize targeting ASP planning, monitoring, and human resources allocation.

Objectives: Carbapenem-resistant Citrobacter spp. (CRC) are increasingly recognized as healthcare-associated pathogens, while systematic studies on clinical epidemiology, genetic diversity, and resistant mechanisms of CRC are relatively scarce. The present study provides comprehensive and systematic research on CRC.

Methods: Clinical isolates of Citrobacter spp. resistant to carbapenems were collected from 5 hospitals across China between October 2014 and December 2017. All the isolates were identified by MALDI-TOF MS and FastANI. Whole-genome sequencing and phylogenetic analyses were performed. Sequencing data were analyzed using MLST, PlasmidFinder, ResFinder, and ISFinder tools.

Results: Thirty-one CRC isolates were isolated from 5 hospitals in different provinces. These strains exhibited significant phylogenetic divergence. ST85 (12.90%) and ST116 (12.90%) were the predominant STs. NDM (41.94%), KPC-2 (25.81%), and IMP (19.35%) were the most frequent carbapenemases of CRC. Interestingly, KPC is frequently associated with C. freundii, while NDM is predominantly observed in C. portucalensis. All the IncX3 and IncN-type plasmids carrying bla_NDM- and most non-type plasmids carrying bla_KPC- were transferrable by conjugation. The genes bla_NDM and bla_KPC were primarily located within relatively conserved genomic environments, including "ISAba125-bla_NDM-ble_MBL-trpF-dsbD-cutA1-groES-groEL-ISCR27" and "Tn3 transposase-ISKpn27-bla_KPC-2-△ISKpn6-korC-kclA-hp-hp-△repB-TnAS1".

Conclusions: The clonal transmission of CRC and the conjugative antibiotic resistance plasmids were the key mechanisms driving the spread of multidrug resistance. It highlights the need to strengthen molecular surveillance, with a focus on high-prevalence clones such as ST85 and ST116 carrying mobile resistance elements.

Objectives: We studied two Klebsiella pneumoniae carbapenemase (KPC)-14 variants from clinical Pseudomonas aeruginosa isolates (C137 and C159) to better understand the genomic diversity, mechanisms, and genes that confer antibiotic resistance and pathogenicity.

Methods: Genomic DNA from C137/159 was subjected to Illumina and Oxford Nanopore sequencing. Horizontal transmission of the plasmid was evaluated using cloning experiments. The expression of efflux pumps, the outer membrane protein OprD, and the enzyme AmpC was quantified using qRT-PCR. The detectability of KPC-14 was evaluated using different methods, and biofilm formation assays and growth curves were assessed.

Results: C137 and C159, sequence type 463 ExoU-positive multidrug-resistant strains, were concurrently resistant to carbapenems and ceftazidime-avibactam (CZA). Both strains possessed five intrinsic antimicrobial resistance genes (fosA, catB7, crpP, bla_PAO, and a bla_OXA-486 variant) as well as bla_KPC-14. In strain C137, bla_KPC-14 was located on a plasmid (pC137). Both strains expressed the bla_KPC-14 gene, concurrent inactivation of OprD, overexpression of the MexX efflux pump, and a pronounced capacity for biofilm formation. The genomic environment of KPC-14 consisted of IS26/IS26/TnpR_Tn3/ISKpn27/ISKpn6/IS26, which classified it as pseudo-compound transposon (PCT). IS26-mediated PCTs may store a variety of resistance genes, including bla_KPC-2 and KPC variants, which are currently disseminating in this region.

Conclusion: The KPC-14 variant presents significant challenges for clinical treatment. The bla_KPC-14 gene carried by PCTs was integrated into the chromosome and exhibited stability throughout bacterial inheritance. Our research highlights the need for improved clinical surveillance of KPC-producing P. aeruginosa.

Objectives: Infections due to carbapenemase-producing Enterobacterales harboring more than one carbapenemase-encoding gene spreads mainly by plasmid and transposon mobilization.

Objectives: Analyze the mobile genetic elements carrying bla_KPC and bla_NDM of K. pneumoniae carbapenemase co-producers (KpKN).

Methods: K. pneumoniae isolates with reduced susceptibility to carbapenems were obtained from 2016 to 2023. To evaluate the genetic environment of KpKN, 22 isolates were selected for antimicrobial susceptibility testing and whole-genome sequencing (WGS).

Results: The bla_KPC-2 gene was carried mainly by IncN/IncFIB, a novel co-integrated plasmid in the Tn4401b transposon. The bla_NDM-1 was disseminated in the only two KpKN isolates recovered before 2020 by IncHI1B/IncFIB plasmid type, in the Tn3000 transposon. Noteworthy, isolates obtained since 2020 showed the bla_NDM-1 gene carried by IncA/C in an IS26-flanked pseudo-composite transposon containing ISCR1, which also had genes that confer resistance to sulfonamides, aminoglycosides, macrolides, quinolones, amphenicols, tetracyclines, rifampicin, sulfonamide, and trimethoprim. The isolates belong mainly to ST11 and ST16.

Conclusions: The plasmid and transposon changes during the different periods could be related to higher dissemination of the bla_NDM-1 and the large number of resistance genes present in the IS26-flanked transposon may have increased the co-selection of this plasmid through the wide use of antimicrobials during the pandemic.

Background: Ceftazidime-avibactam was approved in patients with hospital-acquired pneumonia (HAP), including ventilator-associated pneumonia (VAP), based on the multinational Phase 3 REPROVE study. This study assessed efficacy and safety of ceftazidime-avibactam in Chinese adults with HAP/VAP.

Methods: This was a Phase 4, prospective, multi-centre, open-label study, conducted at 42 sites in China. Patients with HAP/VAP received ceftazidime-avibactam 2.5 g by 2-hour IV infusion every 8 hours for 7-14 days. Primary efficacy endpoint was clinical response at the test-of-cure (TOC) visit in the clinical modified intent-to-treat (cMITT) analysis set. Secondary endpoints included microbiological response at TOC (microbiological modified intent-to-treat; [mMITT] analysis set) and all-cause mortality at TOC and Day 28. Results were summarized descriptively.

Results: Of 257 screened individuals, 235 were treated with ceftazidime-avibactam (safety analysis set); 71% were male; median age was 67 years. Klebsiella pneumoniae (n = 49 [61.3%]) and Pseudomonas aeruginosa (n = 16 [20.0%]) were the most frequently isolated baseline pathogens. Clinical cure at TOC was achieved in 62.7% patients (131/209, 95% CI: [56.0, 69.0]) in the cMITT analysis set. Favourable microbiological responses at TOC occurred in 51.3% (41/80, 95% CI: [40.4, 62.0]) patients (mMITT analysis set). All-cause mortality was 5.7% (12/209; 95% CI: 3.2, 9.6) at TOC and Day 28 (cMITT analysis set). No new safety signals were identified.

Conclusions: Ceftazidime-avibactam was effective in Chinese patients with HAP/VAP, and results were consistent with the Phase 3 REPROVE study. These findings support the use of ceftazidime-avibactam as a potential treatment option in Chinese adults with HAP/VAP.

Objectives: The present study aimed to green synthesize and characterize the zinc nanoparticles (ZNP) and evaluate its potency to control Toxoplasma gondii infection in mice by stimulating the immune system, antioxidant activity, and anti-inflammatory effects.

Methods: By in vivo, T. gondii infected mice were orally treated by ZNP (5-20 mg/kg) for 14 days. The number and size of tissue cysts, oxidant-antioxidant enzymes, the expression of inflammatory cytokines, apoptotic, and pathogenicity-related factors were evaluated by real-time polymerase chain reaction (PCR).

Results: ZNP ranged in size from 10-70 nm with an average size of 45.7±19.4 nm. ZNP treatment resulted in a significant reduction in the number and size of tissue cysts (p<0.05). The oral administration of infected mice with ZNP caused a considerable decrease in malondialdehyde levels and a marked increase (p<0.001) in the activity of the antioxidant enzymes glutathione peroxidase and superoxide dismutase. ZNP administration triggered a significant reduction in the expression levels of the genes of interleukin-1β, tumor necrosis factor-α, nuclear factor kappa B, bradyzoite antigen-1, and B-cell lymphoma-2. Conversely, there was an increase in the expression levels of the genes of IL-10, Serpin A3k, caspase-3, and Bcl-2-associated X protein (P < 0.001).

Conclusion: In summary, the recent investigation illustrated that ZNP demonstrates promising in vivo effects against T. gondii infection in mice. These effects are ascribed to its antioxidant properties, anti-inflammatory characteristics through the inhibition the specific inflammatory cytokines, and its ability to inhibit pathogenicity in mice without any observable signs of toxicity.