Assessment of the activity and mechanisms of resistance to cefiderocol and combinations of ß-lactams and the novel ß-lactamase inhibitors avibactam, taniborbactam, zidebactam, nacubactam, xeruborbactam, and ANT3310 in emerging double-carbapenemase-producing Enterobacterales.

We aimed to investigate the activity of and mechanisms of resistance to cefiderocol and innovative ß-lactam/ß-lactamase inhibitor combinations in a nationwide collection of double-carbapenemase-producing Enterobacterales. In all, 57 clinical isolates co-producing two carbapenemases collected from Spanish hospitals during the period 2017-2022 were analyzed. Minimum inhibitory concentration (MIC) values for ceftazidime, ceftazidime/avibactam, aztreonam, aztreonam/avibactam, aztreonam/nacubactam, cefiderocol, cefepime, cefepime/taniborbactam, cefepime/zidebactam, cefepime/nacubactam, imipenem, imipenem/relebactam, meropenem, meropenem/vaborbactam, meropenem/xeruborbactam, and meropenem/ANT3310 were determined by reference broth microdilution. Genetic drivers of resistance were analyzed by whole-genome sequencing (WGS). The collection covered nine carbapenemase associations: VIM + OXA-48 (21/57), NDM + OXA-48 (11/57), KPC + VIM (10/57), KPC + OXA-48 (6/57), IMP + OXA-48 (3/57), NDM + KPC (2/57), NDM + VIM (2/57), NDM + GES (1/57), and KPC + IMP (1/57). Ceftazidime/avibactam, imipenem/relebactam, and meropenem/vaborbactam were the least active options. Aztreonam/avibactam and aztreonam/nacubactam were active against the whole collection and yielded MIC50/MIC90 values of ≤0.25/0.5 mg/L and 1/2 mg/L, respectively. Cefepime/zidebactam (56/57 susceptible), meropenem/xeruborbactam (56/57 susceptible), cefepime/nacubactam (55/57 susceptible), and cefiderocol (53/57 susceptible) were also highly active, with MIC50/MIC90 values ranging from ≤0.25-2 mg/L to 2-4 mg/L, respectively. Meropenem/ANT3310 (MIC50/MIC90 = 0.5/≥64 mg/L; 47/57 susceptible) and cefepime/taniborbactam (MIC50/MIC90 = 0.5/16 mg/L; 44/57 susceptible) also retained high levels of activity, although they were affected by NDM-type enzymes in combination with porin deficiency. Our findings highlight that cefiderocol and combinations of ß-lactams and the novel ß-lactamase inhibitors avibactam, nacubactam, taniborbactam, zidebactam, xeruborbactam, and ANT3310 show promising activity against double-carbapenemase-producing Enterobacterales.

Mitomycin C as an Anti-Persister Strategy against Klebsiella pneumoniae: Toxicity and Synergy Studies.

The combination of several therapeutic strategies is often seen as a good way to decrease resistance rates, since bacteria can more easily overcome single-drug treatments than multi-drug ones. This strategy is especially attractive when several targets and subpopulations are affected, as it is the case of Klebsiella pneumoniae persister cells, a subpopulation of bacteria able to transiently survive antibiotic exposures. This work aims to evaluate the potential of a repurposed anticancer drug, mitomycin C, combined with the K. pneumoniae lytic phage vB_KpnM-VAC13 in vitro and its safety in an in vivo murine model against two clinical isolates of this pathogen, one of them exhibiting an imipenem-persister phenotype. At the same time, we verified the absence of toxicity of mitomycin C at the concentration using the human chondrocyte cell line T/C28a2. The viability of these human cells was checked using both cytotoxicity assays and flow cytometry.

Characterizing carbapenemase-producing Escherichia coli isolates from Spain: high genetic heterogeneity and wide geographical spread.

Introduction: Carbapenemase-Producing Escherichia coli (CP-Eco) isolates, though less prevalent than other CP-Enterobacterales, have the capacity to rapidly disseminate antibiotic resistance genes (ARGs) and cause serious difficult-to-treat infections. The aim of this study is phenotypically and genotypically characterizing CP-Eco isolates collected from Spain to better understand their resistance mechanisms and population structure. Methods: Ninety representative isolates received from 2015 to 2020 from 25 provinces and 59 hospitals Spanish hospitals were included. Antibiotic susceptibility was determined according to EUCAST guidelines and whole-genome sequencing was performed. Antibiotic resistance and virulence-associated genes, phylogeny and population structure, and carbapenemase genes-carrying plasmids were analyzed. Results and discussion: The 90 CP-Eco isolates were highly polyclonal, where the most prevalent was ST131, detected in 14 (15.6%) of the isolates. The carbapenemase genes detected were bla OXA-48 (45.6%), bla VIM-1 (23.3%), bla NDM-1 (7.8%), bla KPC-3 (6.7%), and bla NDM-5 (6.7%). Forty (44.4%) were resistant to 6 or more antibiotic groups and the most active antibiotics were colistin (98.9%), plazomicin (92.2%) and cefiderocol (92.2%). Four of the seven cefiderocol-resistant isolates belonged to ST167 and six harbored bla NDM. Five of the plazomicin-resistant isolates harbored rmt. IncL plasmids were the most frequent (45.7%) and eight of these harbored bla VIM-1. bla OXA-48 was found in IncF plasmids in eight isolates. Metallo-ß-lactamases were more frequent in isolates with resistance to six or more antibiotic groups, with their genes often present on the same plasmid/integron. ST131 isolates were associated with sat and pap virulence genes. This study highlights the genetic versatility of CP-Eco and its potential to disseminate ARGs and cause community and nosocomial infections.

Activity of cefiderocol and innovative ß-lactam/ß-lactamase inhibitor combinations against isogenic strains of Escherichia coli expressing single and double ß-lactamases under high and low permeability conditions.

OBJECTIVES: To analyse the impact of the most clinically relevant ß-lactamases and their interplay with low outer membrane permeability on the activity of cefiderocol, ceftazidime/avibactam, aztreonam/avibactam, cefepime/enmetazobactam, cefepime/taniborbactam, cefepime/zidebactam, imipenem/relebactam, meropenem/vaborbactam, meropenem/xeruborbactam and meropenem/nacubactam against recombinant Escherichia coli strains. METHODS: We constructed 82 E. coli laboratory transformants expressing the main ß-lactamases circulating in Enterobacterales (70 expressing single ß-lactamase and 12 producing double carbapenemase) under high (E. coli TG1) and low (E. coli HB4) permeability conditions. Antimicrobial susceptibility testing was determined by reference broth microdilution. RESULTS: Aztreonam/avibactam, cefepime/zidebactam, cefiderocol, meropenem/xeruborbactam and meropenem/nacubactam were active against all E. coli TG1 transformants. Imipenem/relebactam, meropenem/vaborbactam, cefepime/taniborbactam and cefepime/enmetazobactam were also highly active, but unstable against most of MBL-producing transformants. Combination of ß-lactamases with porin deficiency (E. coli HB4) did not significantly affect the activity of aztreonam/avibactam, cefepime/zidebactam, cefiderocol or meropenem/nacubactam, but limited the effectiveness of the rest of carbapenem- and cefepime-based combinations. Double-carbapenemase production resulted in the loss of activity of most of the compounds tested, an effect particularly evident for those E. coli HB4 transformants in which MBLs were present. CONCLUSIONS: Our findings highlight the promising activity that cefiderocol and new ß-lactam/ß-lactamase inhibitors have against recombinant E. coli strains expressing widespread ß-lactamases, including when these are combined with low permeability or other enzymes. Aztreonam/avibactam, cefiderocol, cefepime/zidebactam and meropenem/nacubactam will help to mitigate to some extent the urgency of new compounds able to resist MBL action, although NDM enzymes represent a growing challenge against which drug development efforts are still needed.

Corrigendum: Phenotypic and molecular characterization of IMP-producing Enterobacterales in Spain: predominance of IMP-8 in Klebsiella pneumoniae and IMP-22 in Enterobacter roggenkampii.

[This corrects the article DOI: 10.3389/fmicb.2022.1000787.].

Corrigendum: CARB-ES-19 multicenter study of carbapenemase-producing Klebsiella pneumoniae and Escherichia coli from all Spanish provinces reveals interregional spread of high-risk clones such as ST307/OXA-48 and ST512/KPC-3.

[This corrects the article DOI: 10.3389/fmicb.2022.918362.].

Molecular studies of phages-Klebsiella pneumoniae in mucoid environment: innovative use of mucolytic agents prior to the administration of lytic phages.

Mucins are important glycoproteins that form a protective layer throughout the gastrointestinal and respiratory tracts. There is scientific evidence of increase in phage-resistance in the presence of mucin for some bacterial pathogens. Manipulation in mucin composition may ultimately influence the effectiveness of phage therapy. In this work, two clinical strains of K. pneumoniae (K3574 and K3325), were exposed to the lytic bacteriophage vB_KpnS-VAC35 in the presence and absence of mucin on a long-term co-evolution assay, in an attempt to mimic in vitro the exposure to mucins that bacteria and their phages face in vivo. Enumerations of the bacterial and phage counts at regular time intervals were conducted, and extraction of the genomic DNA of co-evolved bacteria to the phage, the mucin and both was performed. We determined the frequency of phage-resistant mutants in the presence and absence of mucin and including a mucolytic agent (N-acetyl L-cysteine, NAC), and sequenced them using Nanopore. We phenotypically demonstrated that the presence of mucin induces the emergence of bacterial resistance against lytic phages, effectively decreased in the presence of NAC. In addition, the genomic analysis revealed some of the genes relevant to the development of phage resistance in long-term co-evolution, with a special focus on the mucoid environment. Genes involved in the metabolism of carbohydrates were mutated in the presence of mucin. In conclusion, the use of mucolytic agents prior to the administration of lytic phages could be an interesting therapeutic option when addressing K. pneumoniae infections in environments where mucin is overproduced.

An increase in erythromycin resistance in methicillin-susceptible Staphylococcus aureus from blood correlates with the use of macrolide/lincosamide/streptogramin antibiotics. EARS-Net Spain (2004-2020).

Objectives: To describe and analyse erythromycin resistance trends in blood isolates of Staphylococcus aureus (EARS-Net Spain, 2004-2020) and the association of these trends with the consumption of macrolide, lincosamide, and streptogramin B (MLSB) antibiotics. To assess molecular changes that could be involved in erythromycin resistance trends by whole genome analysis of representative isolates. Materials and methods: We collected antibiotic susceptibility data for all first-blood S. aureus isolates in patients from 47 Spanish hospitals according to EARS-Net criteria. MLSB antibiotic consumption was obtained from the Spanish Agency for Medicines and Medical Devices (2008-2020). We sequenced 137 representative isolates for core genome multilocus sequence typing, resistome and virulome analysis. Results: For the 36,612 invasive S. aureus isolates, methicillin resistance decreased from 26.4% in 2004 to 22.4% in 2020. Erythromycin resistance in methicillin-susceptible S. aureus (MSSA) increased from 13.6% in 2004 to 28.9% in 2020 (p < 0.001); however, it decreased from 68.7 to 61.8% (p < 0.0001) in methicillin-resistant S. aureus (MRSA). Total consumption of MLSB antibiotics increased from 2.72 defined daily doses per 1,000 inhabitants per day (DID) in 2014 to 3.24 DID in 2016. By WGS, the macrolide resistance genes detected were erm (59.8%), msrA (46%), and mphC (45.2%). The erm genes were more prevalent in MSSA (44/57, 77.2%) than in MRSA (38/80, 47.5%). Most of the erm genes identified in MSSA after 2013 differed from the predominant ermC gene (17/22, 77.3%), largely because ermT was significantly associated with MSSA after 2013 (11/29, 37.9%). All 13 ermT isolates in this study, except one, belonged to ST398 and came from 10 hospitals and six Spanish provinces. Conclusion: The significant increase in erythromycin resistance in blood MSSA correlated with the consumption of the MLSB antibiotics in Spain. These preliminary data seem support the hypothesis that the human ST398 MSSA clade with ermT-mediated resistance to erythromycin may be involved in this trend.

CRISPR-Cas13a-Based Assay for Accurate Detection of OXA-48 and GES Carbapenemases.

Carbapenem-resistant pathogens have been recognized as a health concern as they are both difficult to treat and detect in clinical microbiology laboratories. Researchers are making great efforts to develop highly specific, sensitive, accurate, and rapid diagnostic techniques, required to prevent the spread of these microorganisms and improve the prognosis of patients. In this context, CRISPR-Cas systems are proposed as promising tools for the development of diagnostic methods due to their high specificity; the Cas13a endonuclease can discriminate single nucleotide changes and displays collateral cleavage activity against single-stranded RNA molecules when activated. This technology is usually combined with isothermal pre-amplification reactions in order to increase its sensitivity. We have developed a new LAMP-CRISPR-Cas13a-based assay for the detection of OXA-48 and GES carbapenemases in clinical samples without the need for nucleic acid purification and concentration. To evaluate the assay, we used 68 OXA-48-like-producing Klebsiella pneumoniae clinical isolates as well as 64 Enterobacter cloacae complex GES-6, 14 Pseudomonas aeruginosa GES-5, 9 Serratia marcescens GES-6, 5 P. aeruginosa GES-6, and 3 P. aeruginosa (GES-15, GES-27, and GES-40) and 1 K. pneumoniae GES-2 isolates. The assay, which takes less than 2 h and costs approximately 10 € per reaction, exhibited 100% specificity and sensitivity (99% confidence interval [CI]) for both OXA-48 and all GES carbapenemases. IMPORTANCE Carbapenems are one of the last-resort antibiotics for defense against multidrug-resistant pathogens. Multiple nucleic acid amplification methods, including multiplex PCR, multiplex loop-mediated isothermal amplification (LAMP) and multiplex RPAs, can achieve rapid, accurate, and simultaneous detection of several resistance genes to carbapenems in a single reaction. However, these assays need thermal cycling steps and specialized instruments, giving them limited application in the field. In this work, we adapted with high specificity and sensitivity values, a new LAMP CRISPR-Cas13a-based assay for the detection of OXA-48 and GES carbapenemases in clinical samples without the need for RNA extraction.

Widespread Detection of Yersiniabactin Gene Cluster and Its Encoding Integrative Conjugative Elements (ICEKp) among Nonoutbreak OXA-48-Producing Klebsiella pneumoniae Clinical Isolates from Spain and the Netherlands.

In this study, we determined the presence of virulence factors in nonoutbreak, high-risk clones and other isolates belonging to less common sequence types associated with the spread of OXA-48-producing Klebsiella pneumoniae clinical isolates from The Netherlands (n = 61) and Spain (n = 53). Most isolates shared a chromosomally encoded core of virulence factors, including the enterobactin gene cluster, fimbrial fim and mrk gene clusters, and urea metabolism genes (ureAD). We observed a high diversity of K-Locus and K/O loci combinations, KL17 and KL24 (both 16%), and the O1/O2v1 locus (51%) being the most prevalent in our study. The most prevalent accessory virulence factor was the yersiniabactin gene cluster (66.7%). We found seven yersiniabactin lineages-ybt 9, ybt 10, ybt 13, ybt 14, ybt 16, ybt 17, and ybt 27-which were chromosomally embedded in seven integrative conjugative elements (ICEKp): ICEKp3, ICEKp4, ICEKp2, ICEKp5, ICEKp12, ICEKp10, and ICEKp22, respectively. Multidrug-resistant lineages-ST11, ST101, and ST405-were associated with ybt 10/ICEKp4, ybt 9/ICEKp3, and ybt 27/ICEKp22, respectively. The fimbrial adhesin kpi operon (kpiABCDEFG) was predominant among ST14, ST15, and ST405 isolates, as well as the ferric uptake system kfuABC, which was also predominant among ST101 isolates. No convergence of hypervirulence and resistance was observed in this collection of OXA-48-producing K. pneumoniae clinical isolates. Nevertheless, two isolates, ST133 and ST792, were positive for the genotoxin colibactin gene cluster (ICEKp10). In this study, the integrative conjugative element, ICEKp, was the major vehicle for yersiniabactin and colibactin gene clusters spreading. IMPORTANCE Convergence of multidrug resistance and hypervirulence in Klebsiella pneumoniae isolates has been reported mostly related to sporadic cases or small outbreaks. Nevertheless, little is known about the real prevalence of carbapenem-resistant hypervirulent K. pneumoniae since these two phenomena are often separately studied. In this study, we gathered information on the virulent content of nonoutbreak, high-risk clones (i.e., ST11, ST15, and ST405) and other less common STs associated with the spread of OXA-48-producing K. pneumoniae clinical isolates. The study of virulence content in nonoutbreak isolates can help us to expand information on the genomic landscape of virulence factors in K. pneumoniae population by identifying virulence markers and their mechanisms of spread. Surveillance should focus not only on antimicrobial resistance but also on virulence characteristics to avoid the spread of multidrug and (hyper)virulent K. pneumoniae that may cause untreatable and more severe infections.

Carbapenemase-Producing Klebsiella pneumoniae in COVID-19 Intensive Care Patients: Identification of IncL-VIM-1 Plasmid in Previously Non-Predominant Sequence Types.

During the COVID-19 pandemic, intensive care units (ICUs) operated at or above capacity, and the number of ICU patients coinfected by nosocomial microorganisms increased. Here, we characterize the population structure and resistance mechanisms of carbapenemase-producing Klebsiella pneumoniae (CP-Kpn) from COVID-19 ICU patients and compare them to pre-pandemic populations of CP-Kpn. We analyzed 84 CP-Kpn isolates obtained during the pandemic and 74 CP-Kpn isolates obtained during the pre-pandemic period (2019) by whole genome sequencing, core genome multilocus sequence typing, plasmid reconstruction, and antibiotic susceptibility tests. More CP-Kpn COVID-19 isolates produced OXA-48 (60/84, 71.4%) and VIM-1 (18/84, 21.4%) than KPC (8/84, 9.5%). Fewer pre-pandemic CP-Kpn isolates produced VIM-1 (7/74, 9.5%). Cefiderocol (97.3-100%) and plazomicin (97.5-100%) had the highest antibiotic activity against pandemic and pre-pandemic isolates. Sequence type 307 (ST307) was the most widely distributed ST in both groups. VIM-1-producing isolates belonging to ST307, ST17, ST321 and ST485, (STs infrequently associated to VIM-1) were detected during the COVID-19 period. Class 1 integron Int1-blaVIM-1-aac(6')-1b-dfrB1-aadAI-catB2-qacEΔ1/sul1, found on an IncL plasmid of approximately 70,000 bp, carried blaVIM-1 in ST307, ST17, ST485, and ST321 isolates. Thus, CP-Kpn populations from pandemic and pre-pandemic periods have similarities. However, VIM-1 isolates associated with atypical STs increased during the pandemic, which warrants additional monitoring and surveillance.

Phenotypic and molecular characterization of IMP-producing Enterobacterales in Spain: Predominance of IMP-8 in Klebsiella pneumoniae and IMP-22 in Enterobacter roggenkampii.

Objectives: Little is known about IMP-producing Enterobacterales (IMP-Ent) in Europe. We analyzed at genomic and phenotypic level IMP-Ent isolates circulating in Spain in a 9-year period. Materials and methods: IMP-Ent isolates submitted to our reference laboratory were included. Antibiotic susceptibility was performed using microdilution method (EUCAST), and IMP-carbapenemase activity was measured with carbapenemase inhibitors, the ß-CARBA method, the modified Hodge test (MHT), and the modified carbapenemase inhibition method (mCIM). All isolates collected were sequenced for high-resolution single-nucleotide polymorphism (SNP) typing, core genome multilocus sequence typing (cgMLST), and resistome analysis. Results: Fifty IMP-Ent isolates, collected from 19 hospitals in 13 Spanish provinces, were detected: Klebsiella pneumoniae (IMP-Kpn) (24; 48%), Enterobacter roggenkampii (13; 26%), Enterobacter hormaechei (8, 16%), Klebsiella oxytoca (two; 4%), Enterobacter asburiae (one, 2%), Serratia marcescens (one; 2%) and Escherichia coli (one; 2%). All isolates were positive by the MHT and ß-CARBA tests; 48 (96%) were mCIM positive; 12 (24%) and 26 (52%) displayed positive inhibition with dipicolinic (meropenem) and EDTA (ertapenem), respectively. Five IMP-carbapenemase types were identified: IMP-8 (22; 44%), IMP-22 (17; 34%), IMP-13 (7; 14%), IMP-28 (two; 4%), and IMP-15 (two; 4%), predominating IMP-8 in K. pneumoniae and IMP-22 in E. roggenkampii. IMP-28 was exclusively identified in K. oxytoca and IMP-15 in E. hormaechei. Predominant STs were ST405 (29.2%), ST15 (25%) and ST464 (20.8%) in IMP-Kpn; ST96 (100%) in E. roggenkampii and ST182 (62.5%) in E. hormachei. Colistin and amikacin were the most active non-carbapenem antibiotics against IMP-Ent. Conclusion: IMP-Ent isolates remain infrequent in Spain, although in recent years have been circulating causing nosocomial outbreaks, being IMP-8-producing K. pneumoniae and IMP-22-producing E. roggenkampii the most frequently detected in this study. Inhibition with EDTA or dipicolinic acid presented false negative results in some IMP-producing strains. Active microbiological and molecular surveillance is essential for a better comprehension and control of IMP-Ent dissemination.

CARB-ES-19 Multicenter Study of Carbapenemase-Producing Klebsiella pneumoniae and Escherichia coli From All Spanish Provinces Reveals Interregional Spread of High-Risk Clones Such as ST307/OXA-48 and ST512/KPC-3.

Objectives: CARB-ES-19 is a comprehensive, multicenter, nationwide study integrating whole-genome sequencing (WGS) in the surveillance of carbapenemase-producing K. pneumoniae (CP-Kpn) and E. coli (CP-Eco) to determine their incidence, geographical distribution, phylogeny, and resistance mechanisms in Spain. Methods: In total, 71 hospitals, representing all 50 Spanish provinces, collected the first 10 isolates per hospital (February to May 2019); CPE isolates were first identified according to EUCAST (meropenem MIC > 0.12 mg/L with immunochromatography, colorimetric tests, carbapenem inactivation, or carbapenem hydrolysis with MALDI-TOF). Prevalence and incidence were calculated according to population denominators. Antibiotic susceptibility testing was performed using the microdilution method (EUCAST). All 403 isolates collected were sequenced for high-resolution single-nucleotide polymorphism (SNP) typing, core genome multilocus sequence typing (cgMLST), and resistome analysis. Results: In total, 377 (93.5%) CP-Kpn and 26 (6.5%) CP-Eco isolates were collected from 62 (87.3%) hospitals in 46 (92%) provinces. CP-Kpn was more prevalent in the blood (5.8%, 50/853) than in the urine (1.4%, 201/14,464). The cumulative incidence for both CP-Kpn and CP-Eco was 0.05 per 100 admitted patients. The main carbapenemase genes identified in CP-Kpn were bla OXA-48 (263/377), bla KPC-3 (62/377), bla VIM-1 (28/377), and bla NDM-1 (12/377). All isolates were susceptible to at least two antibiotics. Interregional dissemination of eight high-risk CP-Kpn clones was detected, mainly ST307/OXA-48 (16.4%), ST11/OXA-48 (16.4%), and ST512-ST258/KPC (13.8%). ST512/KPC and ST15/OXA-48 were the most frequent bacteremia-causative clones. The average number of acquired resistance genes was higher in CP-Kpn (7.9) than in CP-Eco (5.5). Conclusion: This study serves as a first step toward WGS integration in the surveillance of carbapenemase-producing Enterobacterales in Spain. We detected important epidemiological changes, including increased CP-Kpn and CP-Eco prevalence and incidence compared to previous studies, wide interregional dissemination, and increased dissemination of high-risk clones, such as ST307/OXA-48 and ST512/KPC-3.

Carbapenemase-producing Pseudomonas aeruginosa in Spain: interregional dissemination of the high-risk clones ST175 and ST244 carrying blaVIM-2, blaVIM-1, blaIMP-8, blaVIM-20 and blaKPC-2.

Carbapenemase-producing (CP) Pseudomonas aeruginosa is rare compared with mutation-driven carbapenem-resistance, but this situation may be changing. A collection of CP P. aeruginosa isolates was characterized in this study. In 2016, 232 unduplicated carbapenem-resistant P. aeruginosa isolates, of which 71 (30.6%) carried carbapenemase genes, were submitted to the Spanish antibiotic reference laboratory and were further analysed by whole-genome sequencing (WGS). Of the 71 CP P. aeruginosa, 39 (54.9%) carried blaVIM-2, 14 (19.7%) blaVIM-1, 8 (11.3%) blaIMP-8, 6 (8.5%) blaVIM-20, 2 (2.8%) blaVIM-2 plus blaKPC-2, one (1.4%) blaIMP-13 and one (1.4%) blaVIM-1 plus blaIMP-18. Four sequence types (ST175, ST244, ST815 and ST155) encompassed 83.1% of the 71 CP P. aeruginosa; ST175 was detected in hospitals from seven provinces. Using core genome multilocus sequence typing (cgMLST), four clusters were detected: Cluster 1 included nine ST815/VIM-2 isolates; Cluster 2 included five ST175/VIM-2 isolates; Cluster 3 included seven ST244 isolates (five VIM-2 and two VIM-2 plus KPC-2); and Cluster 4 included 11 ST175 isolates (seven VIM-2 and four IMP-8). The average number of acquired resistance genes was significantly higher in the blaVIM-1-carying isolates (7.1 ± 0.94) than in the blaVIM-2-carrying isolates (4.5 ± 0.20). CP P. aeruginosa isolates are spreading in Spain, mainly due to the dissemination of high-risk clones such as ST175 and ST244 producing VIM and IMP carbapenemases. Emergence of CP P. aeruginosa is a cause of clinical and epidemiological concern.

Interregional spread in Spain of linezolid-resistant Enterococcus spp. isolates carrying the optrA and poxtA genes.

The emergence of linezolid-resistant Enterococcus spp. (LRE) due to transferable resistance determinants is a matter of concern. To understand the contribution of the plasmid-encoded optrA and poxtA genes to the emergence of LRE, clinical isolates from different Spanish hospitals submitted to the Spanish Reference Laboratory from 2015-2018 were analysed. Linezolid resistance mechanisms were screened in all isolates by PCR and sequencing. Genetic relatedness of Enterococcus spp. carrying optrA and poxtA was studied by PFGE and MLST. Antimicrobial susceptibility was tested by broth microdilution using EUCAST standards. A total of 97 LRE isolates were studied, in 94 (96.9%) of which at least one resistance determinant was detected; 84/97 isolates (86.6%) presented a single resistance mechanism as follows: 45/84 (53.6%) carried the optrA gene, 38/84 (45.2%) carried the G2576T mutation and 1/84 (1.2%) carried the poxtA gene. In addition, 5/97 isolates (5.2%) carried both optrA and the G2576T mutation and 5/97 (5.2%) carried both optrA and poxtA. The optrA gene was more frequent in Enterococcus faecalis (83.6%) than Enterococcus faecium (11.1%) and was mainly associated with community-acquired urinary tract infections. Carriage of the poxtA gene was more frequent in E. faecium (13.9%) than E. faecalis (1.6%). Among the optrA-positive E. faecalis isolates, two main clusters were detected by PFGE. These two clusters belonged to ST585 and ST480 and were distributed throughout 11 and 6 Spanish provinces, respectively. This is the first description of LRE carrying the poxtA gene in Spain, including the co-existence of optrA and poxtA in five isolates.

Emergence of NDM-producing Klebsiella pneumoniae and Escherichia coli in Spain: phylogeny, resistome, virulence and plasmids encoding blaNDM-like genes as determined by WGS.

OBJECTIVES: NDM carbapenemases have spread worldwide. However, little information exists about the impact of NDM-producing Enterobacteriaceae in Spain. By WGS, we sought to elucidate the population structure of NDM-like-producing Klebsiella pneumoniae and Escherichia coli in Spain and to determine the plasmids harbouring blaNDM-like genes. METHODS: High-resolution SNP typing, core-genome MLST and plasmid reconstruction (PlasmidID) were performed on 59 NDM-like-producing K. pneumoniae and 8 NDM-like-producing E. coli isolated over an 8 year period in Spain. RESULTS: Five major epidemic clones of NDM-producing K. pneumoniae caused five important nationwide outbreaks: ST437/NDM-7, ST437/NDM-1, ST147/NDM-1, ST11/NDM-1 and ST101/NDM-1; in contrast, the spread of NDM-producing E. coli was polyclonal. Three blaNDM types were identified: blaNDM-1, 61.2%; blaNDM-7, 32.8%; and blaNDM-5, 6%. Five K. pneumoniae isolates co-produced other carbapenemases (three blaOXA-48 and two blaVIM-1). The average number of acquired resistance genes was higher in K. pneumoniae than in E. coli. The plasmids encoding blaNDM-like genes belonged to IncFII, IncFIB, IncX3, IncR, IncN and IncC types, of which IncF, IncR and IncC were associated with MDR. The genetic surroundings of blaNDM-like genes showed a highly variable region upstream of ISAba125. CONCLUSIONS: In recent years NDM-producing K. pneumoniae and E. coli have emerged in Spain; the spread of a few high-risk K. pneumoniae clones such as ST437/NDM-7, ST437/NDM-1, ST147/NDM-1, ST11/NDM-1 and ST101/NDM-1 have caused several interregional outbreaks. In contrast, the spread of NDM-producing E. coli has been polyclonal. Plasmid types IncFII, IncFIB, IncX3, IncR, IncN and IncC carried blaNDM, and the same IncX3 plasmid was detected in K. pneumoniae and E. coli.

Characterization of Carbapenemase-Producing Klebsiella oxytoca in Spain, 2016-2017.

There is little information about carbapenemase-producing (CP) Klebsiella oxytoca, an important nosocomial pathogen. We characterized CP K. oxytoca isolates collected from different Spanish hospitals between January 2016 and October 2017. During the study period, 139 nonduplicate CP K. oxytoca isolates were identified; of these, 80 were studied in detail. Carbapenemase and extended-spectrum ß-lactamase genes were identified by PCR and sequencing. Genetic relatedness was studied by pulsed-field gel electrophoresis (PFGE). Whole-genome sequencing (WGS), carried out on 12 representative isolates, was used to identify the resistome, to elucidate the phylogeny, and to determine the plasmids harboring carbapenemase genes. Forty-eight (60%) isolates produced VIM-1, 30 (37.5%) produced OXA-48, 3 (3.7%) produced KPC-2, 2 (2.5%) produced KPC-3, and 1 (1.2%) produced NDM-1; 4 isolates coproduced two carbapenemases. By PFGE, 69 patterns were obtained from the 80 CP K. oxytoca isolates, and four well-defined clusters were detected: cluster 1 consisted of 11 OXA-48-producing isolates, and the other three clusters included VIM-1-producing isolates (5, 3, and 3 isolates, respectively). In the 12 sequenced isolates, the average number of acquired resistance genes was significantly higher in VIM-1-producing isolates (10.8) than in OXA-48-producing isolates (2.3). All 12 isolates had chromosomally encoded genes of the blaOXY-2 genotype, and by multilocus sequence typing, most belonged to sequence type 2 (ST2). Carbapenemase genes were carried by IncL, IncHI2, IncFII, IncN, IncC, and IncP6 plasmid types. The emergence of CP K. oxytoca was principally due to the spread of VIM-1- and OXA-48-producing isolates in which VIM-1- and OXA-48 were carried by IncL, IncHI2, IncFII, and IncN plasmids. ST2 and the genotype blaOXY-2 predominated among the 12 sequenced isolates.

Carbapenem-resistant Citrobacter spp. isolated in Spain from 2013 to 2015 produced a variety of carbapenemases including VIM-1, OXA-48, KPC-2, NDM-1 and VIM-2.

OBJECTIVES: There is little information about carbapenemase-producing (CP) Citrobacter spp. We studied the molecular epidemiology and microbiological features of CP Citrobacter spp. isolates collected in Spain (2013-15). METHODS: In total, 119 isolates suspected of being CP by the EUCAST screening cut-off values were analysed. Carbapenemases and ESBLs were characterized using PCR and sequencing. The genetic relationship among Citrobacter freundii isolates was studied by PFGE. RESULTS: Of the 119 isolates, 63 (52.9%) produced carbapenemases, of which 37 (58.7%) produced VIM-1, 20 (31.7%) produced OXA-48, 12 (19%) produced KPC-2, 2 (3.2%) produced NDM-1 and 1 (1.6%) produced VIM-2; 9 C. freundii isolates co-produced VIM-1 plus OXA-48. Fourteen isolates (22.2%) also carried ESBLs: 8 CTX-M-9 plus SHV-12, 2 CTX-M-9, 2 SHV-12 and 2 CTX-M-15. Fifty-seven isolates (90.5%) were C. freundii, 4 (6.3%) were Citrobacter koseri, 1 (1.6%) was Citrobacter amalonaticus and 1 (1.6%) was Citrobacter braakii. By EUCAST breakpoints, eight (12.7%) of the CP isolates were susceptible to the four carbapenems tested. In the 53 CP C. freundii analysed by PFGE, a total of 44 different band patterns were observed. Four PFGE clusters were identified: cluster 1 included eight isolates co-producing VIM-1 and OXA-48; blaVIM-1 was carried in a class 1 integron (intI-blaVIM-1-aacA4-dfrB1-aadA1-catB2-qacEΔ1/sul1) and blaOXA-48 was carried in a Tn1999.2 transposon. CONCLUSIONS: We observed the clonal and polyclonal spread of CP Citrobacter spp. across several Spanish geographical areas. Four species of Citrobacter spp. produced up to five carbapenemase types, including co-production of VIM-1 plus OXA-48. Some CP Citrobacter spp. isolates were susceptible to the four carbapenems tested, a finding with potential clinical implications.