Characterization of ST15-KL112 Klebsiella pneumoniae Co-Harboring Bla oxa-232 and rmtF in China.

Introduction: This study aimed to investigate the emergence and characteristics of carbapenem-resistant Klebsiella pneumoniae (CRKP) strains that demonstrate resistance to multiple antibiotics, including aminoglycosides and tigecycline, in a Chinese hospital. Methods: A group of ten CRKP strains were collected from the nine patients in a Chinese hospital. Antimicrobial Susceptibility Testing (AST) and phenotypic inhibition assays precisely assess bacterial antibiotic resistance. Real-time quantitative PCR (RT-qPCR) was used to analyze the mRNA levels of efflux pump genes (acrA/acrB and oqxA/oqxB) and the regulatory gene (ramA). The core-genome tree and PFGE patterns were analyzed to assess the clonal and horizontal transfer expansion of the strains. Whole-genome sequencing was performed on a clinical isolate of K. pneumoniae named Kpn20 to identify key resistance genes and antimicrobial resistance islands (ARI). Results: The CRKP strains showed high resistance to carbapenems, aminoglycosides (CLSI, 2024), and tigecycline (EUCAST, 2024). The mRNA expression levels of efflux pump genes and regulatory genes were detected by RT-qPCR. All 10 isolates had significant differences compared to the control group of ATCC13883. The core-genome tree and PFGE patterns revealed five clusters, indicating clonal and horizontal transfer expansion. Three key resistance genes (blaoxa-232, blaCTX-M-15 , and rmtF) were observed in the K. pneumoniae clinical isolate Kpn20. Mobile antibiotic resistance islands were identified containing bla CTX-M-15 and rmtF, with multiple insertion sequences and transposons present. The coexistence of bla oxa-232 and rmtF in a high-risk K. pneumoniae strain was reported. Conjugation assay was utilized to investigate the transferability of bla oxa-232-encoding plasmids horizontally. Conclusion: The study highlights the emergence of ST15-KL112 high-risk CRKP strains with multidrug resistance, including to aminoglycosides and tigecycline. The presence of mobile ARI and clonal and horizontal transfer expansion of strains indicate the threat of transmission of these strains. Future research is needed to assess the prevalence of such isolates and develop effective control measures.

Co-occurrence of OXA-232, RmtF-encoding plasmids, and pLVPK-like virulence plasmid contributed to the generation of ST15-KL112 hypervirulent multidrug-resistant Klebsiella pneumoniae.

The emergence of carbapenem-resistant Klebsiella pneumoniae (CRKP) strains and restricted therapeutic options pose a global threat to public health. Aminoglycosides are a wise choice, which can effectively reduce the mortality rate when combined with ß-lactam drugs. However, in this study, we identified a ST15-KL112 CRKP FK3006 which not only exhibited resistance to carbapenems, but also exhibited high level resistance to aminoglycosides. In addition to the multidrug resistant phenotype, FK3006 also owned typical pathogenic characteristic, including hypermucoviscosity and hypervirulence phenotypes. According to the whole-genome sequencing, one pLVPK-like virulence plasmid, and three key resistant plasmids (bla OXA-232, bla CTX-M-15, and rmtF) were observed in FK3006. Compared to other typical ST15 CRKP, the presence of pLVPK-like virulence plasmid (p3006-2) endowed the FK3006 with high virulence features. High siderophore production, more cell invasive and more resistant to serum killing was observed in FK3006. The Galleria mellonella infection model also further confirmed the hypervirulent phenotype of FK3006 in vivo. Moreover, according to the conjugation assay, p3006-2 virulence plasmid also could be induced transfer with the help of conjugative IncFIIK p3006-11 plasmid (bla CTX-M-15). In addition to the transmissible plasmid, several insertion sequences and transposons were found around bla CTX-M-15, and rmtF to generate the mobile antimicrobial resistance island (ARI), which also make a significant contribution to the dissemination of resistant determinants. Overall, we reported the uncommon co-existence of bla OXA-232, rmtF-encoding plasmids, and pLVPK-like virulence plasmid in ST15-KL112 K. pneumoniae. The dissemination threatens of these high-risk elements in K. pneumoniae indicated that future studies are necessary to evaluate the prevalence of such isolates.

A Nationwide Genomic Study of Clinical Klebsiella pneumoniae Carrying blaOXA-232 and rmtF in China.

OXA-232 carbapenemase is becoming a threat in China due to its high prevalence, mortality, and limited treatment options. However, little information is available on the impact of OXA-232-producing Klebsiella pneumoniae in China. This study aims to characterize the clonal relationships, the genetic mechanisms of resistance, and the virulence of OXA-232-producing K. pneumoniae isolates in China. We collected 81 OXA-232-producing K. pneumoniae clinical isolates from 2017 to 2021. Antimicrobial susceptibility testing was performed using the broth microdilution method. Capsular types, multilocus sequence types, virulence genes, antimicrobial resistance (AMR) determinants, plasmid replicon types, and single-nucleotide polymorphism (SNP) phylogeny were inferred from whole-genome sequences. OXA-232-producing K. pneumoniae strains were resistant to most antimicrobial agents. These isolates showed partial differences in susceptibility to carbapenems: all strains were resistant to ertapenem, while the resistance rates to imipenem and meropenem were 67.9% and 97.5%, respectively. Sequencing and capsular diversity analysis of the 81 K. pneumoniae isolates revealed 3 sequence types (ST15, ST231, and one novel ST [ST-V]), 2 K-locus types (KL112 and KL51), and 2 O-locus types (O2V1 and O2V2). The predominant plasmid replicon types associated with the OXA-232 and rmtF genes were ColKP3 (100%) and IncFIB-like (100%). Our study summarized the genetic characteristics of OXA-232-producing K. pneumoniae circulating in China. The results demonstrate the practical applicability of genomic surveillance and its utility in providing methods to prevent transmission. It alerts us to the urgent need for longitudinal surveillance of these transmissible lineages. IMPORTANCE In recent years, the detection rate of carbapenem-resistant K. pneumoniae has increased and represents a major threat to clinical anti-infective therapy. Compared with KPC-type carbapenemases and NDM-type metallo-ß-lactamases, OXA-48 family carbapenemases are another important resistance mechanism mediating bacterial resistance to carbapenems. In this study, we investigated the molecular characteristics of OXA-232 carbapenemase-producing K. pneumoniae isolated from several hospitals to clarify the epidemiological dissemination characteristics of such drug-resistant strains in China.

One Health Spread of 16S Ribosomal RNA Methyltransferase-Harboring Gram-Negative Bacterial Genomes: An Overview of the Americas.

Aminoglycoside antimicrobials remain valuable therapeutic options, but their effectiveness has been threatened by the production of bacterial 16S ribosomal RNA methyltransferases (16S-RMTases). In this study, we evaluated the genomic epidemiology of 16S-RMTase genes among Gram-negative bacteria circulating in the American continent. A total of 4877 16S-RMTase sequences were identified mainly in Enterobacterales and nonfermenting Gram-negative bacilli isolated from humans, animals, foods, and the environment during 1931-2023. Most of the sequences identified were found in the United States, Brazil, Canada, and Mexico, and the prevalence of 16S-RMTase genes have increased in the last five years (2018-2022). The three species most frequently carrying 16S-RMTase genes were Acinetobacter baummannii, Klebsiella pneumoniae, and Escherichia coli. The armA gene was the most prevalent, but other 16S-RMTase genes (e.g., rmtB, rmtE, and rmtF) could be emerging backstage. More than 90% of 16S-RMTase sequences in the Americas were found in North American countries, and although the 16S-RMTase genes were less prevalent in Central and South American countries, these findings may be underestimations due to limited genomic data. Therefore, whole-genome sequence-based studies focusing on aminoglycoside resistance using a One Health approach in low- and middle-income countries should be encouraged.

High Rates of Aminoglycoside Methyltransferases Associated with Metallo-Beta-Lactamases in Multidrug-Resistant and Extensively Drug-Resistant Pseudomonas aeruginosa Clinical Isolates from a Tertiary Care Hospital in Egypt.

BACKGROUND: Multidrug-resistant (MDR) and extensively drug-resistant (XDR) strains of Pseudomonas aeruginosa are the leading cause of healthcare-associated infections worldwide. OBJECTIVE: The aim was to identify the resistant phenotypes among P. aeruginosa and to characterize different aminoglycosides and carbapenem resistance genes as major mechanisms of resistance in these isolates, in Theodor Bilharz Research Institute (TBRI), a tertiary care hospital in Cairo, Egypt. METHODS: During a period of 11 months, 42 P. aeruginosa clinical isolates were collected from the microbiology laboratory by routine culture. Antimicrobial sensitivity testing to the aminoglycosides gentamicin and amikacin, and other classes of antibiotics, was performed by a disk diffusion method. Isolates were tested for aminoglycoside resistance genes, aac(6')-lb, aac-(3)-lla, rmtB, rmtC, armA, rmtD, and rmtF, and carbapenemase resistance genes bla NDM, bla VIM, and bla IMP, using conventional PCR. RESULTS: Thirty-three (78.5%) of the clinical P. aeruginosa isolates showed MDR and XDR phenotypes at 42.4% and 57.65%, respectively, and these were included in the study. Aminoglycoside resistance was found in 97%, whereas carbapenem resistance was found in 81% of the isolates phenotypically. Only 59.4% (19/26) of the aminoglycoside-resistant isolates harbored resistance genes; none of the amikacin-susceptible isolates harbored any of the tested aminoglycoside resistance genes. Aminoglycoside resistance genes rmtB, armA, aac(6')-lb, and rmtF were found at rates of 17/33 (51.5%), 3/33 (9%), 2/33 (6%), and 2/33 (6%), respectively, whereas rmtD, acc(3)-II, and rmtC were not detected. Only 40.7% (11/27) of the carbapenem-resistant isolates harbored resistance genes. Carbapenem resistance genes, bla NDM andbla VIM, were found at rates of 7/33 (21.2%) and 6/33 (18.1%), respectively, and bla IMP was not detected. CONCLUSION: Rates of MDR and XDR P. aeruginosa and resistance to aminoglycosides and carbapenems in our setting are high. Methyltransferases and metallo-beta-lactamases are the main mechanisms of resistance to aminoglycosides and carbapenems, respectively. The presence of bla NDM and rmtF in the strains confirms their rapid dissemination in the Egyptian environment.

Emergence of ST15 Klebsiella pneumoniae Clinical Isolates Producing Plasmids-Mediated RmtF and OXA-232 in China.

BACKGROUND: RmtF, as 16S rRNA methyltransferase, leads to high-level resistance to aminoglycoside and is now barely reported. METHODS AND RESULTS: Three rmtF-positive Klebsiella pneumoniae isolates, belonging to the pandemic clone sequence type 15, were isolated from children and coproduced bla OXA-232 and bla CTX-M-15. The rmtF gene was located on an IncFIB transformable plasmid of 128,536-bp and bla OXA-232 was on a 6141-bp ColKP3 plasmid, respectively. CONCLUSION: Plasmids with rmtF found worldwide, shared relatively low similarity, and merely matched partly in their multidrug resistance region. Notably, clinical isolates coproducing rmtF and bla OXA-232 are gradually increasing in China.

Comparative in vitro activity of plazomicin and older aminoglyosides against Enterobacterales isolates; prevalence of aminoglycoside modifying enzymes and 16S rRNA methyltransferases.

Comparative in vitro activity of plazomicin and 4 older aminoglycosides was evaluated with broth microdilution in 714 blood isolates from 14 hospitals in Turkey. Isolates included Escherichia coli (n=320), Klebsiella spp. (n=294), Enterobacter spp. (n=69), Serratia marcescens (n=20), and Citrobacter spp. (n=11). Isolates resistant to older aminoglycosides (n=240) were screened for aminoglycoside modifying enzyme genes: aac(6')-Ib, aac(3)-Ia, aac(3)-IIa, ant(2″)-Ia. Isolates with high MICs for plazomicin (n=41) were screened for 16S rRNA methyltransferase genes (armA, rmtA, rmtB, rmtC, rmtD, rmtE, rmtF, rmtG, rmtH, npmA) and 2 carbapenemase genes (blaOXA-48, blaNDM-1). Overall, resistance to plazomicin, amikacin, netilmicin, gentamicin, and tobramycin was 7.7%, 7.4%, 31.5%, 32.9%, and 34.7%, respectively. aac(6')-Ib and aac(3)-IIa were the most common AME genes. Co-occurrence of blaNDM-1 with armA and rmtC and blaOXA-48 with armA was striking. Enterobacter cloacae carrying rmtC+blaNDM-1, S. marcescens with armA+blaOXA-48, and rmtF+ blaOXA-48 in K. pneumoniae were reported for the first time.

How do auditory cortex neurons represent communication sounds?

A major goal in auditory neuroscience is to characterize how communication sounds are represented at the cortical level. The present review aims at investigating the role of auditory cortex in the processing of speech, bird songs and other vocalizations, which all are spectrally and temporally highly structured sounds. Whereas earlier studies have simply looked for neurons exhibiting higher firing rates to particular conspecific vocalizations over their modified, artificially synthesized versions, more recent studies determined the coding capacity of temporal spike patterns, which are prominent in primary and non-primary areas (and also in non-auditory cortical areas). In several cases, this information seems to be correlated with the behavioral performance of human or animal subjects, suggesting that spike-timing based coding strategies might set the foundations of our perceptive abilities. Also, it is now clear that the responses of auditory cortex neurons are highly nonlinear and that their responses to natural stimuli cannot be predicted from their responses to artificial stimuli such as moving ripples and broadband noises. Since auditory cortex neurons cannot follow rapid fluctuations of the vocalizations envelope, they only respond at specific time points during communication sounds, which can serve as temporal markers for integrating the temporal and spectral processing taking place at subcortical relays. Thus, the temporal sparse code of auditory cortex neurons can be considered as a first step for generating high level representations of communication sounds independent of the acoustic characteristic of these sounds. This article is part of a Special Issue entitled "Communication Sounds and the Brain: New Directions and Perspectives".