Treatment of Infections Caused by Extended-Spectrum-Beta-Lactamase-, AmpC-, and Carbapenemase-Producing Enterobacteriaceae

β-lactam resistant phenotypes reported by VITEK®2 advanced expert systemTM (AES) compared to whole genome sequencing in Enterobacterales from North and Latin America

The VITEK®2 AES β-lactam phenotypes of 488 Enterobacterales from North and Latin America generated by the VITEK®2 were compared to the resistance genotypes provided by whole genome sequencing (WGS). The AES provided phenotypic reports for 447 (91.6 %) isolates, including isolates harbouring carbapenemases (195; 43.6 %), ESBLs (103; 23.0 %) and transferable AmpCs (tAmpC; 28; 6.3 %) genes, as well as wildtype isolates (WT; 121; 27.1 %). Overall, the AES report was accurate for 433/447 (96.9 %) isolates. The AES accurately reported carbapenemase, ESBL, and tAmpC phenotypes for 93.7 %, 93.7 %, and 98.4 % of isolates, respectively, and sensitivity/specificity rates were 96.4 %/91.7 %, 98.1 %/92.4 %, 82.1 %/99.5 %, and 100 %/98.8 %. 14 isolates carrying carbapenemase (7 total; 3 KPC, 2 MBL, 2 OXA-48-like), ESBL (2), and tAmpC-encoding genes (5) were not correctly identified by AES. The AES phenotypic report detected resistance mechanisms among Enterobacterales rapidly and could significantly aid future antimicrobial stewardship initiatives and patient care.

Prevalence and distribution of carbapenem-resistant Enterobacterales in companion animals: A nationwide study in the United States using commercial laboratory data

BACKGROUND

Carbapenem-resistant Enterobacterales (CRE) are a concern in both human and animal medicine globally. Despite extensive research in humans, limited data exist on CRE in companion animals, with a lack of nationwide prevalence estimates.

HYPOTHESIS/OBJECTIVES

To assess the occurrence and trends of CRE in cats and dogs across the United States by analyzing 4 years of commercial antimicrobial susceptibility testing (AST) data.

ANIMALS

Between 2019 and 2022, 477 426 ASTs were conducted on Enterobacterales isolates against imipenem. Isolates were derived from 379 598 dogs and 97 828 cats. Animal origin was not disclosed.

METHODS

In this retrospective study, antimicrobial susceptibility test data from IDEXX Laboratories were analyzed. Analysis included resistance estimations to imipenem stratified by sampling site, an assessment of resistance patterns over time and location, and the application of space-time cluster analysis to identify potential outbreaks. Antibiograms were produced for carbapenem-resistant isolates.

RESULTS

Susceptibility to imipenem was high, at 98.86%. Temporal analysis indicated stability in susceptibility, with an unexplained reduction in susceptible isolates in June 2019. Spatial analysis identified 2 high-risk clusters along the Western Coast (relative risk [RR]: 23.26; P < .001) and in Texas (RR: 10.72; P < .001) in that month. Three other clusters were found, in Missouri (RR: 39.55; P = .038), Florida (RR: 4.53; P < .001), and New York (RR: 9.20; P < .001).

CONCLUSIONS AND CLINICAL IMPORTANCE

CRE are present at a low prevalence in dogs and cats across the United States. Variations in prevalence across patient-level and environmental factors highlight the need for tailored stewardship programs.

Prevalence and genomic characterization of clinical Escherichia coli strains that harbor the plasmid-borne tet(X4) gene in China

The tigecycline resistance gene tet(X4) has been widely reported in animals and animal products in some Asian countries including China in recent years but only sporadically detected in human. In this study, we investigated the prevalence and genetic features of tet(X4)-positive clinical E. coli strains. A total of 462 fecal samples were collected from patients in four hospitals located in four provinces in China in 2023. Nine tet(X4)-positive E. coli strains were isolated and subjected to characterization of their genetic and phenotypic features by performing antimicrobial susceptibility test, whole-genome sequencing, bioinformatic and phylogenetic analysis. The majority of the test strains were found to exhibit resistance to multiple antimicrobial agents including tigecycline but remained susceptible to colistin and meropenem. A total of seven different sequence types (STs) and an unknown ST type were identified among the nine tet(X4)-positive strains. Notably, the tet(X4) gene in six out of these nine tet(X4)-positive E. coli strains was located in a IncFIA-HI1A-HI1B hybrid plasmid, which was an tet(X4)-bearing epidemic plasmid responsible for dissemination of the tet(X4) gene in China. Furthermore, the tet(X4) gene in four out of nine tet(X4)-positive E. coli isolates could be successfully transferred to E. coli EC600 through conjugation. In conclusion, this study characterized the epidemic tet(X4)-bearing plasmids and tet(X4)-associated genetic environment in clinical E. coli strains, suggested the importance of continuous surveillance of such tet(X4)-bearing plasmids to control the increasingly widespread dissemination of tigecycline-resistant pathogens in clinical settings in China.

Decoding the resistome, virulome and mobilome of clinical versus aquatic Acinetobacter baumannii in southern Romania

Acinetobacter baumannii, a notorious opportunistic pathogen, presents a formidable challenge in both clinical and environmental fields due to its resilience and ability to acquire resistance. This study undertook a comprehensive analysis of 183 A. baumannii isolates collected between 2019 and 2022 from intra-hospital infections (IHI), hospital sewages (Hs), wastewater treatment plants (WWTP), and adjacent river waters from two Southern cities, focusing on their resistome, virulome, and mobilome through isolation on chromogenic media, identification by MALDI-TOF-MS and antibiotic susceptibility testing by disk diffusion) followed by genotypic characterization [Whole Genome Sequencing (WGS), 3rd generation sequencing through the MinION (ONT) platform, pangenome description, and respectively horizontal gene transfer through conjugation assays]. Our findings reveal significant genomic plasticity and the prevalence of high-risk international clones, underlining the potential of these isolates to act as reservoirs for antibiotic resistance genes (ARGs) that could be dynamically exchanged between clinical and environmental settings through mobile genetic elements (MGEs) such as the pMAL1 plasmids and the critical role of WWTPs in the persistence and spread of A. baumannii. Moreover, our study presents the first report of the co-occurrence of bla OXA-23 and bla OXA-72 in A. baumannii ST2 clone. Thus, our research underscores the necessity for integrated surveillance and targeted interventions across healthcare and environmental sectors to mitigate the risk posed by this adaptable pathogen.

New Agents Are Coming, and So Is the Resistance

Antimicrobial resistance is a global threat that requires urgent attention to slow the spread of resistant pathogens. The United States Centers for Disease Control and Prevention (CDC) has emphasized clinician-driven antimicrobial stewardship approaches including the reporting and proper documentation of antimicrobial usage and resistance. Additional efforts have targeted the development of new antimicrobial agents, but narrow profit margins have hindered manufacturers from investing in novel antimicrobials for clinical use and therefore the production of new antibiotics has decreased. In order to combat this, both antimicrobial drug discovery processes and healthcare reimbursement programs must be improved. Without action, this poses a high probability to culminate in a deadly post-antibiotic era. This review will highlight some of the global health challenges faced both today and in the future. Furthermore, the new Infectious Diseases Society of America (IDSA) guidelines for resistant Gram-negative pathogens will be discussed. This includes new antimicrobial agents which have gained or are likely to gain FDA approval. Emphasis will be placed on which human pathogens each of these agents cover, as well as how these new agents could be utilized in clinical practice.

Global emergence of double and multi-carbapenemase producing organisms: epidemiology, clinical significance, and evolutionary benefits on antimicrobial resistance and virulence

Redundant carbapenemase-producing (RCP) bacteria, which carry double or multiple carbapenemases, represent a new and concerning phenomenon. The objective of this study is to conduct a comprehensive analysis of the epidemiology and genetic mechanisms of RCP strains to support targeted surveillance and control measures. A retrospective analysis was conducted using surveillance data from 277 articles. Statistical analysis was performed to determine and evaluate species prevalence, proportions of carbapenemases, antibiotic susceptibility profiles, sample information, and patient outcomes. Complete plasmid sequencing data were utilized to investigate potential antimicrobial resistance or virulence advantages that strains may gain from acquiring redundant carbapenemases. RCP bacteria are widely distributed globally, and their prevalence is increasing over time. Several countries, including China, India, Iran, Turkey, and South Korea, have reported more than 100 RCP strains. The most commonly reported RCP species are Klebsiella pneumoniae and Acinetobacter baumannii, which exhibit varying proportions of carbapenemase combinations. Certain species-carbapenemase combinations, such as K. pneumoniae carrying New Delhi metallo-β-lactamase (NDM) + oxacillinase (OXA) (56.76%) and K. pneumoniae carbapenemase (KPC) + Verona integron-encoded metallo-β-lactamase (VIM) (50.00%) carbapenemases, are associated with high mortality rates. In patients with RCP strains isolated from the bloodstream and respiratory system, the mortality rates are 58.70% and 69.23%, respectively. Analysis of plasmids from RCP strains suggests that they may acquire additional antibiotic resistance phenotypes and virulence factors. Carbapenem-resistant bacteria carrying redundant carbapenemases pose a significant global health threat. This study provides valuable insights into the epidemiology and genetic mechanisms of these bacteria, supporting the development of effective control and prevention strategies to mitigate their transmission.IMPORTANCEThis study examined the global distribution patterns of 1,780 bacteria with double or multiple carbapenemases from 277 articles and assessed their clinical impact. The presence of multiple carbapenemases increases the chances of co-resistance to other classes of antibiotics and more virulence factors, further complicating the clinical management of infections.

Metabolomics unveil key pathways underlying the synergistic activities of aztreonam and avibactam against multidrug-resistant Escherichia coli

PURPOSE

Aztreonam/avibactam is effective against serious infections caused by Gram-negative bacteria including Enterobacterales harboring metallo-β-lactamases. While the utility of this combination has been established in vitro and in clinical trials, the purpose of this study is to enhance our understanding of the underlying mechanism responsible for their activities through metabolomic profiling of a multidrug-resistant Escherichia coli clinical isolate.

METHODS

Metabolomic analyses of time-dependent changes in endogenous bacterial metabolites in a clinical isolate of a multidrug-resistant E. coli treated with aztreonam and avibactam were performed. E. coli metabolomes were compared at 15 min, 1 h and 24 h following treatments with either avibactam (4 mg/L), aztreonam (4 mg/L), or aztreonam (4 mg/L) + avibactam (4 mg/L).

RESULTS

Drug treatment affected 326 metabolites with magnitude changes of at least 2-fold, most of which are involved primarily in peptidoglycan biosynthesis, nucleotide metabolism, and lipid metabolism. The feedstocks for peptidoglycan synthesis were depleted by aztreonam/avibactam combination; a significant downstream increase in nucleotide metabolites and a release of lipids were observed at the three timepoints.

CONCLUSION

The findings indicate that the aztreonam/avibactam combination accelerates structural damage to the bacterial membrane structure and their actions were immediate and sustained compared to aztreonam or avibactam alone. By inhibiting the production of crucial cell wall precursors, the combination may have inflicted damages on bacterial DNA.

ESKAPE pathogens: antimicrobial resistance, epidemiology, clinical impact and therapeutics

The rise of antibiotic resistance and a dwindling antimicrobial pipeline have been recognized as emerging threats to public health. The ESKAPE pathogens - Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa and Enterobacter spp. - were initially identified as critical multidrug-resistant bacteria for which effective therapies were rapidly needed. Now, entering the third decade of the twenty-first century, and despite the introduction of several new antibiotics and antibiotic adjuvants, such as novel β-lactamase inhibitors, these organisms continue to represent major therapeutic challenges. These bacteria share several key biological features, including adaptations for survival in the modern health-care setting, diverse methods for acquiring resistance determinants and the dissemination of successful high-risk clones around the world. With the advent of next-generation sequencing, novel tools to track and combat the spread of these organisms have rapidly evolved, as well as renewed interest in non-traditional antibiotic approaches. In this Review, we explore the current epidemiology and clinical impact of this important group of bacterial pathogens and discuss relevant mechanisms of resistance to recently introduced antibiotics that affect their use in clinical settings. Furthermore, we discuss emerging therapeutic strategies needed for effective patient care in the era of widespread antimicrobial resistance.

Dissemination of IncC plasmids in Salmonella enterica serovar Thompson recovered from seafood and human diarrheic patients in China

Salmonella Thompson is a prevalent foodborne pathogen and a major threat to food safety and public health. This study aims to reveal the dissemination mechanism of S. Thompson with co-resistance to ceftriaxone and ciprofloxacin. In this study, 181 S. Thompson isolates were obtained from a retrospective screening on 2118 serotyped Salmonella isolates from foods and patients, which were disseminated in 12 of 16 districts in Shanghai, China. A total of 10 (5.5 %) S. Thompson isolates exhibited resistance to ceftriaxone (MIC ranging from 8 to 32 μg/mL) and ciprofloxacin (MIC ranging from 2 to 8 μg/mL). The AmpC β-lactamase gene blaCMY-2 and plasmid-mediated quinolone resistance (PMQR) genes of qnrS and qepA were identified in the 9 isolates. Conjugation results showed that the co-transfer of blaCMY-2, qnrS, and qepA occurred on the IncC plasmids with sizes of ∼150 (n = 8) or ∼138 (n = 1) kbp. Three typical modules of ISEcp1-blaCMY-2-blc-sugE, IS26-IS15DIV-qnrS-ISKpn19, and ISCR3-qepA-intl1 were identified in an ST3 IncC plasmid pSH11G0791. Phylogenetic analysis indicated that IncC plasmids evolved into Lineages 1, 2, and 3. IncC plasmids from China including pSH11G0791 in this study fell into Lineage 1 with those from the USA, suggesting their close genotype relationship. In conclusion, to our knowledge, it is the first report of the co-existence of blaCMY-2, qnrS, and qepA in IncC plasmids, and the conjugational transfer contributed to their dissemination in S. Thompson. These findings underline further challenges for the prevention and treatment of Enterobacteriaceae infections posed by IncC plasmids bearing blaCMY-2, qnrS, and qepA.

Carbapenemase producing Enterobacterales at a large teaching hospital in Ohio: comparison to state surveillance and retrospective analysis of patient characteristics

Background

The presence of carbapenemase-producing carbapenem-resistant Enterobacterales (CP-CRE) around the world is increasing, particularly in healthcare settings. Surveillance testing for plasmid-mediated carbapenemase genes is necessary to tracking CP-CRE infections.

Aim

In the state of Ohio, surveillance of carbapenem-resistant Enterobacterales (CRE) began in 2018, and to the authors' knowledge data on these cases has not been published to date. This study analyzed data on CRE from a large teaching hospital in Ohio, and by the Ohio Department of Health Laboratory (ODHL).

Methods

Carbapenemase production was detected using mCIM, and plasmid-mediated carbapenemase genes were detected using rtPCR. Data was collected on 344 standard-of-care isolates from a large teaching hospital in Ohio, including data collected from chart review. Deidentified surveillance data on 4,391 CRE isolates was provided by the ODHL. Statistical analysis was performed using binary logistic regression.

Findings

While KPC was the most common carbapenemase gene (n=1590), NDM (n=98), VIM (n=10), IMP (n=39) and OXA-48 (n=35) were also detected in the isolates studied. Klebsiella pneumoniae and Enterobacter cloacae were the most common CRE, and carbapenemase genes were most commonly detected in K. pneumoniae. Inpatient hospital stays and long-term care were associated with CP-CRE and were more common in women.

Conclusion

Surveillance data shows that CP-CRE are present in Ohio, most commonly in Klebsiella pneumoniae. A better understanding of the prevalence of CRE, plasmid-mediated carbapenemase genes present, and the populations affected are important when tracking the spread of disease. Further study and surveillance of carbapenem-resistant organisms can provide a better understanding of their prevalence in the state.

Outcomes and Predictors of Mortality in Patients With KPC-Kp Infections Treated With Meropenem Vaborbactam: An Observational Multicenter Study

Background

Meropenem-vaborbactam is a recent and promising option for the treatment of KPC-producing Klebsiella pneumoniae (KPC-Kp) infections, including those resistant to ceftazidime-avibactam.

Methods

We conducted a retrospective analysis of observational data from 19 Italian hospitals on use and outcomes of patients treated with meropenem-vaborbactam for at least ≥24 hours for KPC-Kp infections. Crude and propensity-weighted multiple Cox regression models were performed to ascertain risk factors independently associated with 30-day mortality.

Results

The cohort included 342 adults with bloodstream infections (n = 172) and nonbacteremic infections (n = 170), of which 107 were lower respiratory tract infections, 30 were complicated urinary tract infections, and 33 were infections involving other sites. Most infections (62.3%) were managed with meropenem-vaborbactam monotherapy, or in combination with at least 1 other active drug (usually fosfomycin, tigecycline, or gentamicin) (37.7%). The 30-day mortality rate was 31.6% (108/342). In multiple Cox regression model, 30-day mortality was independently associated with septic shock at infection onset, Charlson comorbidity index ≥ 3, dialysis, concomitant COVID-19, and INCREMENT score ≥ 8. Administration of meropenem-vaborbactam within 48 hours from infection onset was a negative predictor of mortality. All predictors, except administration of meropenem-vaborbactam within 48 hours, remained significant when the multiple Cox regression model was repeated after adjustment for the propensity score for receipt of combination therapy.

Conclusions

Despite the limits of a retrospective study, the data derived from this multicenter cohort provide additional evidence on the efficacy of meropenem-vaborbactam in treating severe KPC-Kp infections, even when used as monotherapy.

Shift in the dominant sequence type of carbapenem-resistant Klebsiella pneumonia infection from ST278-NDM-1 to ST11-KPC-2 in neonatal patients in a children's hospital in Shanghai, China, 2017-2021

OBJECTIVES

To investigate the clinical characteristics and molecular epidemiology of CRKP infection in neonatal patients in a children's hospital in China from 2017 to 2021.

METHODS

Species identification and antibiotic susceptibilities were tested with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and VITEK 2 systems. The clinical data were collected from medical records. Carbapenem-resistant Klebsiella pneumoniae (CRKP) isolates were investigated by antimicrobial susceptibility testing, carbapenemase genes and multilocus sequence typing.

RESULTS

Six kinds of resistant genes and 23 STs were detected. BlaNDM-1 (n=83, 55.3%) was the predominant carbapenemase gene, followed by blaKPC-2 (n=45, 30.0%), blaNDM-5 (n=7, 4.7%), blaIMP-38 (n=6, 4.0%). BlaNDM-1 was predominant in 2017 and 2018, whereas blaKPC-2 increased in 2019 and became the predominant gene from 2020 to 2021. ST11 accounted for most infections (n=35, 23.3%), followed by ST278 (n=23, 15.3%), ST17 (n=17, 11. 3%) and ST2735 (n=16, 10.7%). ST278 and ST17 were predominant in 2017 and 2018, whereas ST11 increased in 2019 and became the predominant sequence type from 2020 to 2021. Compared with blaNDM-1, the CRKP strains producing blaKPC-2 were characterized by high resistance to gentamicin, amikacin and levofloxacin and the change trend of drug resistance rate before and after COVID-19 was consistent with that of blaNDM-1 and blaKPC-2.

CONCLUSIONS

The main sequence type of CRKP infection changed dynamically from ST278-NDM-1 to ST11-KPC-2 during the years 2017-2021 in the newborns. Antibiotic exposure and the prevalence of COVID-19 since 2020 may have led to changes in hospital population and lead to the changes.

Antimicrobial resistance and AmpC production in ESBL-producing Klebsiella pneumoniae and Klebsiella quasipneumoniae: A retrospective study in Japanese clinical isolates

INTRODUCTION

The study of Klebsiella quasipneumoniae, Klebsiella variicola, and AmpC production in extended-spectrum β-lactamase (ESBL)-producing Klebsiella in Japan is limited, and existing data are insufficient. This study aims to characterize Klebsiella species, determine AmpC production rates, and analyze antimicrobial resistance patterns in ESBL-producing Klebsiella isolates in Japan.

METHODS

A total of 139 clinical isolates of ESBL-producing Klebsiella were collected in Japan, along with their corresponding antimicrobial susceptibility profiles. The isolates were identified using a web-based tool. ESBL genes within the isolates were identified using multiplex PCR. Screening for AmpC-producing isolates was performed using cefoxitin disks, followed by multiplex PCR to detect the presence of AmpC genes. Antimicrobial resistance patterns were analyzed across the predominant ESBL genotypes.

RESULTS

The web-based tool identified 135 isolates (97.1%) as Klebsiella pneumoniae and 4 (2.9%) as K. quasipneumoniae subsp. similipneumoniae, with no instances of K. variicola detected. Among K. pneumoniae, the CTX-M-1 group emerged as the predominant genotype (83/135, 61.5%), followed by K. quasipneumoniae subsp. similipneumoniae (3/4, 75.0%). The CTX-M-9 group was the second most prevalent genotype in K. pneumoniae (45/135, 33.3%). The high resistance rates were observed for quinolones (ranging from 46.7% to 63.0%) and trimethoprim/sulfamethoxazole (78.5%). The CTX-M-1 group exhibited higher resistance to ciprofloxacin (66/83, 79.5%) compared to the CTX-M-9 group (18/45, 40.0%), a trend also observed for levofloxacin and trimethoprim/sulfamethoxazole. Among the 16 isolates that tested positive during AmpC screening, only one K. pneumoniae isolates (0.7%) were confirmed to carry the AmpC gene.

CONCLUSION

Klebsiella pneumoniae with the CTX-M-1 group is the most common ESBL-producing Klebsiella in Japan and showed a low proportion of AmpC production. These isolates are resistant to quinolones and trimethoprim/sulfamethoxazole, highlighting the challenge of managing this pathogen. The findings underscore the importance of broader research and continuous monitoring to address the resistance patterns of ESBL-producing Klebsiella.

Global phylogeography and genomic characterization of blaKPC and blaNDM-positive clinical Klebsiella aerogenes isolates from China, 2016-2022

Carbapenem-resistant Klebsiella aerogenes (CRKA), being one of the members of carbapenem-resistant Enterobacteriaceae (CRE), has caused great public health concern, but with fewer studies compared to other CRE members. Furthermore, studies on phylogenetic analysis based on whole genome Single-Nucleotide Polymorphism (SNP) of CRKA were limited. Here, 20 CRKA isolates (11 blaKPC-2-bearing and 9 blaNDM-1/5-harboring) were characterized by antimicrobial susceptibility testing, conjugation assay, whole genome sequencing (WGS) and bioinformatics analysis. Additionally, the phylogeographic relationships of K. aerogenes were further investigated from public databases. All isolates were multidrug-resistant (MDR) bacteria, and they demonstrated susceptibility to colistin. Most blaKPC-2 or blaNDM-1/5-carrying plasmids were found to be conjugative. Phylogenetic analysis revealed the clonal dissemination of K. aerogenes primarily occurred within clinical settings. Notably, some strains in this study showed the potential for clonal transmission, sharing few SNPs between K. aerogenes and KPC- and/or NDM-positive K. aerogenes isolated from various countries. The STs of K. aerogenes strains had significant diversity. WGS analysis showed that the IncFIIK plasmid was the most prevalent carrier of blaKPC-2, and, blaNDM-1/5 were detected on the IncX3 plasmids. The Tn6296 and Tn3000 transposons were most common vehicles for facilitating the transmission of blaKPC-2 and blaNDM-1/5, respectively. This study highlights the importance of continuous screening and surveillance by WGS for analysis of drug-resistant strains in hospital settings, and provide clinical information that supports epidemiological and public health research on human pathogens.

Epidemiology, Microbiology, and Risk Factors of Bacterial Bloodstream Infections in Patients After Allogeneic Hematopoietic Stem Cell Transplantation

Purpose

To investigate the clinical characteristics, etiology, and risk factors of bacterial bloodstream infection (BSI) in allogeneic hematopoietic stem cell transplantation (allo-HSCT) recipients. This study also aimed to provide a clinical basis for early identification of high-risk patients and optimization of empirical antimicrobial treatment.

Patients and Methods

This is a retrospective study of clinical data during agranulocytosis from 331 patients with hematological malignancies who underwent allo-HSCT at our institute between January 2016 and December 2022. The incidence, distribution and drug resistance patterns, and the risk factors of BSI were analyzed.

Results

Among the 331 HSCT patients, 250 had febrile neutropenia and 45 cases were found to have BSI. The incidence of BSI in patients with agranulocytosis fever was 18% (45/250). A total of 48 pathogens were isolated during BSI episodes, gram-negative bacteria (GNB) accounted for 70.8% (34/48), gram-positive bacteria (GPB) for 29.2% (14/48). Multivariate analysis revealed that ≥grade 2 acute graft-versus-host disease (aGVHD) and previous BSI within 6 months before HSCT were independently associated with an increased occurrence of BSI. Coagulase-negative staphylococci (CoNS) and Escherichia coli were the most commonly isolated GPB and GNB, respectively. A total of 32 GNB were tested for drug susceptibility, the detection rate of carbapenem-resistant Enterobacteriaceae (CRE) was 12.5% (4/32), and extended-spectrum β-lactamase (ESBL) accounted for 56.3% (18/32).

Conclusion

BSIs are still a common and severe complication after allo-HSCT. In our center, BSIs in allo-HSCT patients are dominated by gram-negative bacteria and the resistance rate to carbapenem drugs is high. Risk factors for BSI during agranulocytosis were previous BSI within 6 months before HSCT and ≥grade 2 aGVHD.

Efficacy of cefoperazone/sulbactam for ESBL-producing Escherichia coli and Klebsiella pneumoniae bacteraemia and the factors associated with poor outcomes

OBJECTIVE

We aimed to assess the efficacy of cefoperazone/sulbactam (CPZ/SUL) in extended-spectrum β-lactamase (ESBL)-producing Enterobacterales infections and identify factors influencing outcomes.

METHODS

This retrospective multicentre study was conducted in Taiwan (January 2015 to December 2020) and examined the efficacy of CPZ/SUL treatment in ESBL-producing Enterobacterales bacteraemia. The minimum inhibitory concentrations (MICs) were determined using agar dilution; ESBL/AmpC genes were detected using polymerase chain reaction. The primary outcome was clinical success, whereas the secondary outcome was 30-day mortality. Clinical success was defined as the complete resolution of clinical signs and symptoms of K. pneumoniae or E. coli infection, with no evidence of persistent or recurrent bacteraemia. The factors influencing outcomes were identified using a multivariate analysis.

RESULTS

CPZ/SUL demonstrated a clinical success rate of 82.7% (91/110) in treating ESBL-producing Enterobacterales bacteraemia, with a 30-day mortality rate of 9.1% (10/110). Among 110 ESBL-producing isolates, a high clinical success rate was observed at an MIC of ≤32/32 mg/L. Multivariate analysis revealed that a Charlson comorbidity index (CCI) of ≥6 was associated with lower clinical success [odds ratio (OR): 5.80, 95% confidence interval (CI): 1.15-29.14, P = 0.033]. High Sequential Organ Failure Assessment scores (≥6) were significantly associated with increased 30-day mortality (OR: 14.34, 95% CI: 1.45-141.82, P = 0.023).

DISCUSSION

CPZ/SUL demonstrated a clinical success rate of 82.7% (91/110) in treating ESBL-producing Enterobacterales bacteraemia. Treatment success was evident when the CPZ and SUL MIC was ≤32/32 mg/L. Comorbidities (CCI ≥6) were associated with lower clinical success, while disease severity (Sequential Organ Failure Assessment score ≥6) correlated with higher mortality.

Antimicrobial efficacy of eravacycline against emerging extensively drug-resistant (XDR) Acinetobacter baumannii isolates

PURPOSE

Drug-resistant Acinetobacter baumannii is an emerging threat. This study has been conducted to observe the efficacy of eravacycline along with the RND-efflux pump system.

METHODS

A cross-sectional study was done collecting 48 clinical isolates of Acinetobacter baumannii. MICs of 15 antibiotics were detected along with BMD of tigecycline and eravacycline. PCR products of drug-resistant regulatory genes were sequenced and analyzed.

RESULTS

Of the total 48 Isolates, 35 (72.91%) were XDR and 13 (27.08%) were MDR. Out of all, 60.41% of isolates were found to be susceptible to eravacycline by BMD according to both FDA and EUCAST guidelines. A 2-fold decline of MIC50/90 was observed with the use of eravacycline compared to tigecycline. RND-efflux genes like AdeC in 30 (62.5%) isolates and Regulatory gene AdeS in 29 (60.41%) isolates were detected, explaining the existing resistance mechanism.

CONCLUSIONS

XDR Acinetobacter poses an escalating threat due to its resistance to multiple antibiotics, raising serious concerns in healthcare settings. Eravacycline is an encouraging new drug for empirical use in severe infection caused due to the same. Molecular investigation and strict antimicrobial stewardship should be followed to control the emergence, and a better understanding of mechanisms of resistance to prevent the spread of drug-resistant isolates.

Genomic and epidemiological insight of an outbreak of carbapenemase-producing Enterobacterales in a Portuguese hospital with the emergence of the new KPC-124

BACKGROUND

Carbapenemase-producing Enterobacterales (CPE) is an increasing problem in healthcare settings. This study aimed to identify the source of a CPE outbreak that occurred in 2022, in a tertiary hospital in the North of Portugal, to identify exposed patients, and to assess the risk of becoming CPE-positive following hospital admission.

METHODS

A multi-disciplinary investigation was conducted including descriptive, analytical, and molecular epidemiology, environmental screening, and assessment of infection control measures. Clinical and environmental isolates were analyzed using whole-genome sequencing and phylogenetic analysis. Additionally, a prospective observational cohort study was conducted to further investigate the risk factors associated with the emergence of new cases in cohorts of CPE-negative admitted patients.

RESULTS

We observed the presence of multispecies KPC-, IMP-, and/or NDM-producing isolates. Genetically indistinguishable clinical and environmental isolates were found on the same room/ward. The ST45 KPC-3-producing Klebsiella pneumoniae clone was the responsible for the outbreak. During patients' treatment, we detected the emergence of resistance to ceftazidime-avibactam, associated with mutations in the blaKPC-3 gene (blaKPC-46, blaKPC-66 and blaKPC-124, the last variant never previously reported), suggesting a vertical evolutionary trajectory. Patients aged ≥ 75 years, hygiene/feeding-care dependent, and/or subjected to secretion aspiration were risk factors for CPE colonization after hospital admission. Additionally, cases with previous admission to the emergency department suggest that CPE dissemination may occur not only during hospitalization but also in the emergency department.

CONCLUSION

Overall, the study highlights that selection pressure with antibiotics, like ceftazidime-avibactam, is a contributing factor to the emergence of new β-lactamase variants and antibiotic resistance. It also shows that the hospital environment can be a significant source of CPE transmission, and that routine use of infection control measures and real-time molecular epidemiology investigations are essential to ensure the long-term termination of CPE outbreaks and prevent future resurgences.

Emergence of plasmid-mediated high-level tigecycline resistance gene tet(X4) in Enterobacterales from retail aquatic products

The spread of antimicrobial-resistant microbes and genes in various foods poses a significant threat to public health. Of particular global concern is the plasmid-mediated tigecycline resistance gene tet(X4), which, while identified in various sources, has not hitherto been reported in aquatic products. This study aimed to investigate the occurrence and characterization of tigecycline-resistant strains from aquatic products. A total of 73 nonrepetitive seafood samples were purchased from 26 farmers' markets to detect tigecycline-resistant strains. Of these, nine Escherichia coli strains (comprising two ST58, one ST195, ST10, ST48, ST88, ST877, ST1244, ST14462) and one Citrobacter meridianamericanus, recovered from nine (12.33 %, 9/73) seafood samples (fish, n = 7; shrimp, clam and crab, n = 1 respectively), were positive for the tet(X4). Notably, phylogenetic analysis showed that E. coli ST195, a common ST carrying tet(X4), has a close phylogenetic relationship (23∼48 SNPs) with 32 tet(X4)-harboring E. coli ST195 isolates (isolated from pigs, animal foods, vegetable, and humans) deposited in NCBI database. Additionally, E. coli ST58 was closely (2 SNPs) related to one tet(X4)-positive E. coli strain from retail vegetables documented in the NCBI database. Whole genome sequencing and bioinformatic analysis revealed that tet(X4) genes were located on IncX1 (7 E. coli) or hybrid plasmid IncFIA(HI1)/IncHI1B(R27)/IncHI1A (2 E.coli and one C. meridianamericanus). These plasmids displayed high homology with those of plasmids from other sources deposited in GenBank database. These findings underscore the role of epidemic clones and plasmids in driving the dissemination of tet(X4) gene within Enterobacterales of aquatic products origin. To the best of our knowledge, this is the first report of tet(X4)-positive Enterobacterales from aquatic products. The pervasive propagation of tet(X4) gene facilitated by epidemic plasmids and clones across food animals, food products, humans, and the environment presents a serious threat to public health.

Daily occupational exposure in swine farm alters human skin microbiota and antibiotic resistome

Antimicrobial resistance (AMR) is a major threat to global public health, and antibiotic resistance genes (ARGs) are widely distributed across humans, animals, and environment. Farming environments are emerging as a key research area for ARGs and antibiotic resistant bacteria (ARB). While the skin is an important reservoir of ARGs and ARB, transmission mechanisms between farming environments and human skin remain unclear. Previous studies confirmed that swine farm environmental exposures alter skin microbiome, but the timeline of these changes is ill defined. To improve understanding of these changes and to determine the specific time, we designed a cohort study of swine farm workers and students through collected skin and environmental samples to explore the impact of daily occupational exposure in swine farm on human skin microbiome. Results indicated that exposure to livestock-associated environments where microorganisms are richer than school environment can reshape the human skin microbiome and antibiotic resistome. Exposure of 5 h was sufficient to modify the microbiome and ARG structure in workers' skin by enriching microorganisms and ARGs. These changes were preserved once formed. Further analysis indicated that ARGs carried by host microorganisms may transfer between the environment with workers' skin and have the potential to expand to the general population using farm workers as an ARG vector. These results raised concerns about potential transmission of ARGs to the broader community. Therefore, it is necessary to take corresponding intervention measures in the production process to reduce the possibility of ARGs and ARB transmission.

Long-term outcomes of an educational paediatric antimicrobial stewardship programme: a quality improvement study

BACKGROUND AND OBJECTIVES

Antimicrobial stewardship programmes (ASPs) have resulted in antimicrobial consumption (AMC) reduction and quality of prescription (QOP) improvement. However, evidence of ASP impact in paediatrics is still limited. This study aims to assess a paediatric ASP long-term outcomes.

METHODS

A quality improvement study assessed by a interrupted time series analysis was conducted in a paediatric tertiary hospital. QOP expressed as proportion of adequate prescriptions, AMC measured by defined daily dose incidence per 1000 occupied bed days, incidence density of bloodstream infections (BSIs) and its related all-cause crude death rate (CDR) were compared between pre (from January 2013 to December 2015) and post (from January 2016 to December 2019) ASP activities intensification, which included a dedicated paediatric infectious diseases physician to actively perform educational interviews with prescribers.

RESULTS

Inappropriate prescribing showed a significant downward shift associated to the intervention with a -51.4% (-61.2% to -41.8%) reduction with respect to the expected values. Overall AMC showed no trend change after the intervention. For neonatology a28.8% (-36.8% to -20.9%) reduction was observed. Overall anti-pseudomonal cephalosporin use showed a -51.2% (-57.0% to -45.4%) reduction. Decreasing trends were observed for carbapenem use, with a quarterly per cent change (QPC) of -2.4% (-4.3% to -0.4%) and BSI-related CDR (QPC=-3.6%; -5.4% to -1.7%) through the study period. Healthcare-associated multi-drug-resistant BSI remained stable (QPC=2.1; -0.6 to 4.9).

CONCLUSIONS

Intensification of counselling educational activities within an ASP suggests to improve QOP and to partially reduce AMC in paediatric patients. The decreasing trends in mortality remained unchanged.

Prevalence of drug resistant Enterobacteriaceae in a Nepalese tertiary care hospital

Antimicrobial resistance in Enterobacteriaceae is an emerging global public health problem. Numerous studies have reported community-acquired AmpC beta-lactamase and extended spectrum beta-lactamase (ESBL) producing Enterobacteriaceae in Nepal. However, there are limited data on community-acquired Metallo-beta-lactamase (MBL) producing Enterobacteriaceae. A hospital-based descriptive cross-sectional study was conducted using 294 Enterobacteriaceae isolates from a total of 2,345 different clinical specimens collected from patients attending a tertiary care hospital in Nepal. Bacteria were isolated using standard microbiological growth media and identified using biochemical tests. For antimicrobial susceptibility testing, Kirby-Bauer disc diffusion technique was used. AmpC, ESBL, and MBL productions were detected by using combined disc method. AmpC, ESBL, and MBL productions were detected in 19.4%, 29.6%, and 8.5% of total Enterobacteriaceae isolates respectively. Higher rates of beta-lactamases production were seen among the isolates from in-patients in comparison with those from out-patients. However, 11.6%, 25%, and 3.7% of the total isolates from out-patients were AmpC, ESBL, and MBL producers respectively. The co-production of the beta-lactamases was also detected, with two Klebsiella pneumoniae isolates producing all three beta-lactamases. One MBL producing Proteus vulgaris isolate that was pan-resistant with no remaining treatment options was also isolated. Prevalence of drug resistant Enterobacteriaceae in our study was very high. Detection of AmpC, ESBL, and MBL positive isolates from out-patients, who did not have recent history of hospital visit, indicated the community dissemination of the drug resistant bacteria. This is a matter of great concern and an immediate attention to formulate strategies to prevent further development and spread of antibiotic resistance is required.

In Vitro Antimicrobial Activity of Five Newly Approved Antibiotics against Carbapenemase-Producing Enterobacteria-A Pilot Study in Bulgaria

To solve the problem with pan-drug resistant and extensively drug-resistant Gram-negative microbes, newly approved drugs such as ceftazidime/avibactam, cefiderocol, plazomicin, meropenem/vaborbactam, and eravacycline have been introduced in practice. The aim of the present study was to collect carbapenemase-producing clinical Enterobacterales isolates, to characterize their carbapenemase genes and clonal relatedness, and to detect their susceptibility to commonly used antimicrobials and the above-mentioned newly approved antibiotics. Sixty-four carbapenemase producers were collected in a period of one year from four Bulgarian hospitals, mainly including Klebsiella pneumoniae (89% of the isolates) and also single Proteus mirabilis, Providencia stuartii and Citrobacter freundii isolates. The main genotype was blaNDM-1 (in 61%), followed by blaKPC-2 (23%), blaVIM-1 (7.8%) and blaOXA-48 (7.8%). Many isolates showed the presence of ESBL (blaCTX-M-15/-3 in 76.6%) and AmpC (blaCMY-4 in 37.5% or blaCMY-99 in 7.8% of isolates). The most common MLST type was K. pneumoniae ST11 (57.8%), followed by ST340 (12.5%), ST258 (6.3%) and ST101 (6.3%). The isolates were highly resistant to standard-group antibiotics, except they were susceptible to tigecycline (83.1%), colistin (79.7%), fosfomycin (32.8%), and aminoglycosides (20.3-35.9%). Among the newly approved compounds, plazomicin (90.6%) and eravacycline (76.3%) showed the best activity. Susceptibility to ceftazidime/avibactam and meropenem/vaborbactam was 34.4% and 27.6%, respectively. For cefiderocol, a large discrepancy was observed between the percentages of susceptible isolates according to EUCAST susceptibility breakpoints (37.5%) and those of CLSI (71.8%), detected by the disk diffusion method. This study is the first report to show patterns of susceptibility to five newly approved antibiotics among molecularly characterized isolates in Bulgaria. The data may contribute to both the improvement of treatment of individual patients and the choice of infection control strategy and antibiotic policy.

SMT-738: a novel small-molecule inhibitor of bacterial lipoprotein transport targeting Enterobacteriaceae

Carbapenem-resistant Enterobacteriaceae (CREs) are described by the Centers for Disease Control as an urgent threat, and there is a critical need for new therapeutic agents able to treat infections caused by these pathogens. Herein, we describe the microbiological profile, the mechanism f action, and the in vitro safety as well as the pharmacokinetic (PK)/PD profile of SMT-738, a small molecule belonging to a new chemical class. SMT-738 is active against Enterobacterales [including multi-drug-resistant Escherichia coli with 90% of isolates having a minimum inhibitory concentration (MIC90) of 1 µg/mL and Klebsiella pneumoniae 2 µg/mL] and inactive against a broad panel of Gram-negative and Gram-positive pathogens. SMT-738 displays rapid bactericidal activity (2-4 h) and has a low propensity for resistance development (less than ~10-9). Characterization of resistant mutants following exposure to SMT-738 identified mutations within the lipoprotein transport complex (LolCDE), a clinically unexploited and essential bacterial molecular target in Gram-negative bacteria. SMT-738 has a promising in vitro toxicology profile. Furthermore, PK studies demonstrated that when dosed intravenously, SMT-738 maintained exposure levels across infection sites (bloodstream/urinary tract/lung). Proof-of-concept studies across multiple murine in vivo infection models (bloodstream/pneumonia/urinary tract) demonstrated that SMT-738 significantly reduced the bacterial burden compared to baseline and vehicle control. SMT-738 represents a promising novel drug candidate being developed to address clinically challenging serious life-threatening infections caused by highly resistant Enterobacteriaceae including CRE.

Clinical and Microbiological Risk Factors for 30-Day Mortality of Bloodstream Infections Caused by OXA-48-Producing Klebsiella pneumoniae

Bloodstream infections (BSI) caused by carbapenem-resistant Klebsiella pneumoniae are associated with high morbidity and mortality, and the therapy options available for their treatment are frequently scarce. The aim of this study was to analyze risk factors for 30-day mortality in patients with BSI caused by OXA-48-producing K. pneumoniae. The clinical and treatment features of the patients, who attended a single hospital over a five-year period, were retrospectively reviewed. The microbiological features, including the sequence types (ST) and the somatic (O) and capsular (K) antigens, as well as their resistance properties, comprising phenotypes and genetic background, were also considered. To identify the risk factors for 30-day mortality, uni- and multivariate statistical analyses were performed. The univariate analysis revealed statistically significant correlations for age, male gender, lower respiratory system infection, infection by ST147 isolates, and infection by isolates expressing the K64 antigen. The multivariate analysis, applied to variables yielding p-values close to or lower than 0.05 in the univariate analysis, confirmed gender, lower respiratory system infection, and infection with ST147 isolates, but not age or infection with K64 isolates, as risk factors for 30-day mortality. Moreover, the multivariate analysis showed that patients suffering from hematological malignancies or having been treated with inappropriate therapy, both having p-values slightly higher than 0.05 in the univariate analysis, exhibited significantly poorer outcomes in the multivariant analysis. The association of the ST147 clone with an increased risk of mortality is a novel finding that deserves further attention. Studies like the one presented here can certainly benefit the management of patients with nosocomial BSI caused by carbapenemase-producing K. pneumoniae.

Photodynamic therapy for the treatment of Pseudomonas aeruginosa infections: A scoping review

BACKGROUND

Pseudomonas aeruginosa is a Gram-negative bacillus that causes superficial and deep infections, which can be minor to life-threatening. Recently, P. aeruginosa has gained significant relevance due to the increased incidence of multidrug-resistant (MDR) strains that complicate antibiotic treatment. Due to MDR strains, alternative therapies, such as antimicrobial photodynamic therapy (PDT), are presented as a good option to treat nonsystemic infections. PDT combines a photosensitizer agent (PS), light, and oxygen to generate free radicals that destroy bacterial structures such as the envelope, matrix, and genetic material. This work aimed to identify the development stage of the PDT applied to P. aeruginosa to conclude which research stage should be emphasized more.

METHODS

Systematic bibliographic search in various public databases was performed. Related articles were identified using keywords, and relevant ones were selected using inclusion and exclusion criteria according to the PRISMA protocol.

RESULTS

We found 29 articles that meet the criteria, constituting a good body of evidence associated with using PDT against P. aeruginosa in vitro and less developed for in vivo research.

CONCLUSIONS

We conclude that PDT could become an effective adjunct to antimicrobial therapy against P. aeruginosa. This effectiveness depends on the PS used and the location of the infection. Many PS already demonstrated efficacy in PDT, but the evidence is supported significantly by in vitro and very few in vivo studies. Therefore, we conclude that further research efforts should focus on demonstrating the safety and efficacy of these PSs in vivo in animal infection models.

High Prevalence of Carbapenem-Resistant Enterobacterales Colonization Among Intensive Care Unit Patients in a Tertiary Hospital, China

Intestinal colonization with carbapenem-resistant Enterobacterales (CRE) has been shown as a significant risk factor for subsequent CRE infections, especially in intensive care units (ICUs). The aim of this study was to determine the prevalence of intestinal CRE colonization among ICU patients in a Chinese tertiary hospital. Fecal sample screenings for CRE were performed on ICU patients weekly. Antibiotic-susceptibility profile of CRE strains was determined using the Vitek-2 analysis system and broth microdilution method. The carbapenemases of all isolates were determined by phenotypes and genotypes. Clonal relatedness was analyzed by pulsed-field gel electrophoresis (PFGE). Whole-genome sequencing was used to identify the multilocus sequence type (ST), plasmid replicons, and insertion sequences (ISs) of isolates. The overall colonization rate of CRE was 40.4% (82/203). A total of 84 CRE strains were detected, mostly with Klebsiella pneumoniae (92.9%). Antibiotic susceptibility testing profile revealed that 84 CRE strains were resistant to most antibiotics except for tigecycline and colistin. The carbapenemase-encoding genes including blaKPC-2, blaNDM-1, and blaIMP-4 were detected, and blaKPC-2 was the predominant genotype (90.8%). A total of 9 STs were identified among 84 CRE strains, and ST11 was the most common type (83.3%). A variety of mobile genetic elements, including plasmids and ISs, were detected via online tool prediction. PFGE analysis of the 78 K. pneumoniae strains showed 8 different pulsotypes, and pulsotype A was highly prevalent. This study found that the prevalence of CRE colonization was alarmingly high in the ICU, and that effective infection control measures are urgently needed to prevent the dissemination of CRE.

Evaluation of the BioFire® FilmArray® Pneumonia plus Panel for Detecting Bacterial Etiological Agents of Lower Respiratory Tract Infections in an Oncologic Hospital. Comparison with Conventional Culture Method

Conventional methods used to determine pneumonia pathogens are characterized by low sensitivity and long turnaround times. Introducing new tests with better parameters in patients at higher risk of infections is highly anticipated. The results of the conventional quantitative culture method (CM) in determining the bacterial etiology of pneumonia were compared with the results of the Pneumonia plus Panel test (PNP; BioFire® Diagnostics, USA) in 79 samples of bronchoalveolar lavage (BAL). Materials were collected from 79 patients with suspected pneumonia treated in an oncologic hospital due to solid tumors. Only 16/79 BAL samples (20.3%) were true positive (TP) for bacterial etiology in CM vs. 27/79 samples (34.2%) true positive in the PNP test. The total agreement between methods of interpreting the result (positive or negative) was 84.8%. The most prevalent pathogens in both methods were Staphylococcus aureus, followed by Escherichia coli, Pseudomonas aeruginosa, and Haemophilus influenzae. The PNP test identified several respiratory pathogens that were not grown in culture. The semiquantitative value reported by the PNP test was higher than that reported by culture. The PNP test vs. combined test (PNP test and CM methods) demonstrated positive predictive value (PPV) and negative predictive value (NPV) values of 100.0% and 98.1%, and the sensitivity and specificity were 96.4% and 100.0%. The PNP test is a good tool for determining the etiology of bacterial pneumonia and may support the care of an oncologic patient. However, further large-sample studies are needed to research in strictly defined groups of oncologic patients.

Extended-spectrum β-lactamases producing Enterobacteriaceae (ESBL-PE) prevalence in Nepal: A systematic review and meta-analysis

An alarming increase in the occurrence of extended-spectrum β-lactamase-producing Enterobacteriaceae (ESBL-PE) has threatened the treatment and management of bacterial infections. This systematic review and meta-analysis aimed to provide a quantitative estimate of the prevalence of ESBL among the members of the Enterobacteriaceae family by analyzing the community-based and clinical studies published between 2011 and 2021 from Nepal and determine if ESBL-PE correlates with multidrug resistance (MDR). The Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines were followed for systematic review and meta-analysis and the articles' quality was assessed using the Newcastle-Ottawa scale. Of the 2529 articles screened, 65 articles were systematically reviewed, data extracted, and included in in-depth meta-analysis. The overall pooled prevalence of ESBL-producers in Enterobacteriaceae was 29 % (95 % CI: 26-32 %) with high heterogeneity (I2 = 96 %, p < 0.001). Escherichia coli was the predominant ESBL-producing member of the Enterobacteriaceae family, followed by Citrobacter spp. and Klebsiella spp. The prevalence of ESBL-PE increased from 18.7 % in 2011 to 29.5 % in 2021. A strong positive correlation (r = 0.98) was observed between ESBL production and MDR in Enterobacteriaceae. ESBL-PE isolates showed high resistance to ampicillin, cephalosporins, and amoxicillin-clavulanic acid, and blaCTX-M type was the most reported gene variant among ESBL-PE. In conclusion, this study demonstrated an increased prevalence of ESBL-PE in Nepal over the last decade, and such isolates showed a high level of MDR against the β-lactams and non-β-lactam antibiotics. Tackling the rising antibiotic resistance (AR) and MDR in ESBL-PE would require concerted efforts from all stakeholders to institute effective infection control programs in the community and clinical settings.

Efficacy and safety of ceftazidime/avibactam in patients with infections caused by β-lactamase-producing Gram-negative pathogens: a pooled analysis from the Phase 3 clinical trial programme

OBJECTIVES

This post hoc pooled analysis evaluated clinical and microbiological outcomes and safety in patients with infections caused by β-lactamase-producing Gram-negative pathogens across five Phase 3, randomized, controlled, multicentre trials of ceftazidime/avibactam in adults with complicated intra-abdominal infection (cIAI), complicated urinary tract infection (cUTI)/pyelonephritis and nosocomial pneumonia (NP), including ventilator-associated pneumonia (VAP).

METHODS

In each trial, RECLAIM/RECLAIM 3 (cIAI), REPRISE (cIAI/cUTI), RECAPTURE (cUTI) and REPROVE (NP, including VAP) patients were randomized 1:1 to IV ceftazidime/avibactam (plus metronidazole for patients with cIAI) or comparators (carbapenems in >97% patients) for 5-21 days. Clinical and microbiological responses at the test-of-cure visit were assessed for patients with ESBLs, and/or plasmidic and/or overexpression of chromosomal AmpC, and/or serine carbapenemases without MBLs identified in baseline Gram-negative isolates by phenotypic screening and molecular characterization in the pooled microbiological modified ITT (mMITT) population.

RESULTS

In total, 813 patients (ceftazidime/avibactam, n = 389; comparator, n = 424) had ≥1 β-lactamase-producing baseline pathogen identified, amongst whom 792 patients (ceftazidime/avibactam, n = 379; comparator, n = 413) had no MBLs. The most frequent β-lactamase-producing pathogens across treatment groups were Escherichia coli (n = 381), Klebsiella pneumoniae (n = 261) and Pseudomonas aeruginosa (n = 53). Clinical cure rates in the pooled non-MBL β-lactamase-producing mMITT population were 88.1% (334/379) for ceftazidime/avibactam and 88.1% (364/413) for comparators; favourable microbiological response rates were 76.5% (290/379) and 68.8% (284/413), respectively. The safety profile of ceftazidime/avibactam was consistent with previous observations.

CONCLUSIONS

This analysis provides supportive evidence of the efficacy and safety of ceftazidime/avibactam in patients with infections caused by ESBLs, AmpC and serine carbapenemase-producing Gram-negative pathogens.

TRIAL REGISTRATION

NCT01499290; NCT01726023; NCT01644643; NCT01595438/NCT01599806; NCT01808092.

Utilization of an immunochromatographic lateral flow assay for rapid detection of carbapenemase production in gram negative bacilli

BACKGROUND

Rapid detection of carbapenemase production in gram negative bacilli has important treatment considerations.

OBJECTIVE

We evaluated a lateral flow assay (LFA) for carbapenemase production compared with molecular detection of 5 (blaKPC, blaNDM, blaVIM, blaIMP, and blaOXA-48) carbapenemase genes.

METHODS

A total of 218 carbapenem nonsusceptible strains, including species of Enterobacterales, Pseudomonas aeruginosa isolated from clinical cultures were tested using the Cepheid Xpert Carba-R assay and the NG Biotech Carba-5 lateral flow immunoassay.

RESULTS

Overall agreement with LFA was 98.2% with accuracy for each target >99% compared with polymerase chain reaction. Results were available within 15 minutes compared with 1 hour for molecular detection.

CONCLUSION

The use of accurate, rapid diagnostics compliments antimicrobial stewardship programs.

Clinical features, microbial spectrum, and antibiotic susceptibility patterns of spontaneous bacterial peritonitis in cirrhotic patients

BACKGROUND AND AIMS

The microbial spectrum and antimicrobial resistance patterns change over time and vary across regions in patients with spontaneous bacterial peritonitis (SBP). There is an urgent need to clarify the factors associated with in-hospital mortality in these patients.

METHODS

In this study, 377 patients with SBP and 794 patients with bacterascites were analyzed for the microbial spectrum, antimicrobial resistance profiles, and laboratory findings.

RESULTS

The most common pathogens were Escherichia coli (96, 25.5%), Staphylococcus epidermidis (55, 14.6%), and Enterococcus faecium (42, 11.1%). Multidrug-resistant (MDR) bacteria comprised 49.7% of gram-positive bacteria (GPB) and 48.8% of gram-negative bacteria (GNB). The most sensitive antibiotics were amikacin (91.5%), meropenem (89.8%) and piperacillin/tazobactam (87.6%). Extensively drug-resistant (XDR) (OR=51.457, p < 0.001), neutrophil count (OR=1.088, p < 0.001), and the model for end-stage liver disease (MELD) score (OR=1.124, p < 0.001) were independent predictive factors of in-hospital mortality in patients with SBP.

CONCLUSION

MDR represented nearly half of the bacteria isolated from patients with SBP, of which the high prevalence of extended-spectrum β-lactamase-producing and Carbapenem-resistant bacteria is concerning. The presence of XDR, higher MELD score, and neutrophil count were independent predictive factors associated with higher in-hospital mortality in patients with SBP, indicating that intensive care should be provided to these patients.

The burden of hospital acquired infections and antimicrobial resistance

The burden of Hospital care-associated infections (HCAIs) is becoming a global concern. This is compounded by the emergence of virulent and high-risk bacterial strains such as "ESKAPE" pathogens - (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa and Enterobacter species), especially within Intensive care units (ICUs) that house high-risk and immunocompromised patients. In this review, we discuss the contributions of AMR pathogens to the increasing burden of HCAIs and provide insights into AMR mechanisms, with a particular focus on last-resort antibiotics like polymyxins. We extensively discuss how structural modifications of surface-membrane lipopolysaccharides and cationic interactions influence and inform AMR, and subsequent severity of HCAIs. We highlight some bacterial phenotypic survival mechanisms against polymyxins. Lastly, we discuss the emergence of plasmid-mediated resistance as a phenomenon making mitigation of AMR difficult, especially within the ICUs. This review provides a balanced perspective on the burden of HCAIs, associated pathogens, implication of AMR and factors influencing emerging AMR mechanisms.

Empirical cefepime+vancomycin versus ceftazidime+vancomycin versus meropenem+vancomycin in the treatment of healthcare-associated meningitis: results of the multicenter ephesus study

BACKGROUND

Herein, we analyzed the efficacy of main antibiotic therapy regimens in the treatment of healthcare-associated meningitis (HCAM).

MATERIALS/METHODS

This retrospective cohort study was conducted in 18 tertiary-care academic hospitals Turkey, India, Egypt and Romania. We extracted data and outcomes of all patients with post-neurosurgical meningitis cases fulfilling the study inclusion criteria and treated with empirical therapy between December 2006-September 2018.

RESULTS

Twenty patients in the cefepime + vancomycin-(CV) group, 31 patients in the ceftazidime + vancomycin-(CFV) group, and 119 patients in the meropenem + vancomycin-(MV) group met the inclusion criteria. The MV subgroup had a significantly higher mean Glasgow Coma Score, a higher rate of admission to the intensive care unit within the previous month, and a higher rate of antibiot herapy within the previous month before the meningitis episode (p < 0.05). Microbiological success on Day 3-5, end of treatment (EOT) clinical success (80% vs. 54.8%% vs 57.9%), and overall success (EOT success followed by one-month survival without relapse or reinfection 65% vs. 51.6% vs. 45.3%), EOT all cause mortality (ACM) and day 30 ACM (15% vs. 22.6% vs. 26%) did not differ significantly (p > 0.05) among the three cohorts. No regimen was effective against carbapenem-resistant bacteria, and vancomycin resulted in an EOT clinical success rate of 60.6% in the methicillin-resistant staphylococci or ampicillin-resistant enterococci subgroup (n = 34).

CONCLUSIONS

Our study showed no significant difference in terms of clinical success and mortality among the three treatment options. All regimens were ineffective against carbapenem-resistant bacteria. Vancomycin was unsuccessful in approximately 40% of cases involving methicillin-resistant staphylococci or ampicillin-resistant enterococci.

Cefepime in vivo activity against carbapenem-resistant Enterobacterales that test as cefepime susceptible or susceptible-dose dependent in vitro: implications for clinical microbiology laboratory and clinicians

BACKGROUND

Carbapenem-resistant Enterobacterales (CRE) are a public health concern. Among these isolates, there are reports of isolates that test as cefepime susceptible or susceptible-dose dependent (SDD) in vitro despite presence of a carbapenemase. This study aimed to evaluate the pharmacokinetic/pharmacodynamic profile of cefepime against carbapenemase-producing (CP-CRE) and non-producing (non-CP-CRE) isolates with a range of cefepime MICs.

METHODS

Reference broth microdilution and modified carbapenem inactivation method (mCIM) were performed on genotypically characterized clinical CRE isolates. Ultimately, CP-CRE (n = 21; blaKPC) and non-CP-CRE (n = 19) isolates with a distribution of cefepime MICs (≤0.5 to >256 mg/L) were utilized in the murine thigh infection model. Mice were treated with cefepime human-simulated regimens (HSRs) representative of a standard dose (1 g q12h 0.5 h infusion) or the SDD dose (2 g q8h 0.5 h infusion). Efficacy was assessed as the change in bacterial growth at 24 h compared with 0 h control, where ≥1 log bacterial reduction is considered translational value for clinical efficacy.

RESULTS

Among both cohorts of CRE isolates, i.e. CP-CRE and non-CP-CRE, that tested as SDD to cefepime in vitro, 1 log bacterial reduction was not attainable with cefepime. Further blunting of cefepime efficacy was observed among CP-CRE isolates compared with non-CP-CRE across both susceptible and SDD categories.

CONCLUSIONS

Data indicate to avoid cefepime for the treatment of serious infections caused by CRE isolates that test as cefepime susceptible or SDD. Data also provide evidence that isolates with the same antibiotic MIC may have different pharmacokinetic/pharmacodynamic profiles due to their antimicrobial resistance mechanism.

In vitro synergy screens of FDA-approved drugs reveal novel zidovudine- and azithromycin-based combinations with last-line antibiotics against Klebsiella pneumoniae

Treatment of infections caused by multi-drug resistant (MDR) enterobacteria remains challenging due to the limited therapeutic options available. Drug repurposing could accelerate the development of new urgently needed successful interventions. This work aimed to identify and characterise novel drug combinations against Klebsiella pneumoniae based on the concepts of synergy and drug repurposing. We first performed a semi-qualitative high-throughput synergy screen (sHTSS) with tigecycline, colistin and fosfomycin (last-line antibiotics against MDR Enterobacteriaceae) against a FDA-library containing 1430 clinically approved drugs; a total of 109 compounds potentiated any of the last-line antibiotics. Selected hits were further validated by secondary checkerboard (CBA) and time-kill (TKA) assays, obtaining 15.09% and 65.85% confirmation rates, respectively. Accordingly, TKA were used for synergy classification based on determination of bactericidal activities at 8, 24 and 48 h, selecting 27 combinations against K. pneumoniae. Among them, zidovudine or azithromycin combinations with last-line antibiotics were further evaluated by TKA against a panel of 12 MDR/XDR K. pneumoniae strains, and their activities confronted with those clinical combinations currently used for MDR enterobacteria treatment; these combinations showed better bactericidal activities than usual treatments without added cytotoxicity. Our studies show that sHTSS paired to TKA are powerful tools for the identification and characterisation of novel synergistic drug combinations against K. pneumoniae. Further pre-clinical studies might support the translational potential of zidovudine- and azithromycin-based combinations for the treatment of these infections.

Emergence of novel tigecycline resistance gene tet(X5) variant in multidrug-resistant Acinetobacter indicus of swine farming environments

Antibiotic-resistant bacteria are emerging all the time, but the continued emergence of novel resistance genes and genetic structures is even more alarming. Tigecycline is currently the important last barrier in the treatment of multidrug-resistant (MDR) infections. tet(X), a resistance gene to tigecycline, is the most prevalent and constantly emerging novel variants. In this research, we characterized two MDR Acinetobacter indicus strains to tigecycline that were identified and analyzed by antimicrobial susceptibility testing, conjugation transfer, whole genome sequencing (WGS) and bioinformatics analysis, and gene function analysis. The results showed that three tet(X) variants were carried in BDT201, including tet(X6) on the chromosome, tet(X3) on the plasmid pBDT201-2, and a novel tet(X5) variant adjacent to the ISAba1 elements on the plasmid pBDT201-3. The novel Tet(X5) variant showed 98.7% amino acid identity with Tet(X5) and was named Tet(X5.4). By expressing tet(X5.4) gene, the tigecycline minimum inhibitory concentration (MIC) values for Escherichia coli JM109 increased 32- fold (from 0.13 to 4 mg/L). BDT2076 contained tigecycline and carbapenems resistance genes, such as tet(X3), blaOXA-58, blaNDM-3, and blaCARB-2. The continuous emergence of MDR bacteria and resistance genes is a global environmental health issue that can not be ignored and therefore needs to pay more urgent attention to it.

Carbapenem-Resistant Klebsiella pneumoniae in COVID-19 Era-Challenges and Solutions

The COVID-19 era brought about new medical challenges, which, together with nosocomial bacterial infections, resulted in an enormous burden for the healthcare system. One of the most alarming nosocomial threats was carbapenem-resistant Klebsiella pneumoniae (CRKP). Monitoring CRKP incidence and antimicrobial resistance globally and locally is vitally important. In a retrospective study, the incidence of CRKP in the pre-COVID-19 period (2017-2019) and the COVID-19 pandemic (2020-2022) was investigated in the Central Military Hospital in Ružomberok, Slovak Republic. The relative incidence of CRKP significantly increased during the COVID-19 period-by 4.8 times, from 0.18 to 0.76%. At the same time, 47% of CRKP-positive patients also had COVID-19. Twenty-six KPC and sixty-nine NDM-producing isolates were identified. CRKPs isolated in the year 2022 were submitted to whole genome sequencing, and their susceptibility was tested to cefiderocol, ceftazidime-avibactam, imipenem-relebactam and meropenem-vaborbactam, with excellent results. KPC-producing isolates were also highly susceptible to colistin (92%). The NDM isolates revealed lower susceptibility rates, including only 57% colistin susceptibility. ST-307 prevailed in KPC and ST-11 in NDM isolates. Despite the excellent activity of new antimicrobials, rational antibiotic policy must be thoroughly followed, supported by complementary treatments and strict anti-epidemic precautions.

Intra-abdominal infection after tumor surgery: tigecycline combined with β-lactam antibiotics versus tigecycline alone

BACKGROUNDS

Tigecycline has a broad spectrum of antimicrobial activity and has been approved for the treatment of complicated intra-abdominal infections. However, it is debatable whether tigecycline should be used alone or in combination. This study aimed to investigate whether tigecycline plus β-lactam antibiotics (combination therapy [CT] group) are superior to tigecycline alone (monotherapy [MT] group) in non-critically ill intra-abdominal infection patients after tumor surgery.

METHODS

This was a multicenter, retrospective cohort study. The primary outcome was mortality during the hospital stay. Secondary outcomes were clinical success rate, microbial eradication rate, relapse rate within one week, course of treatment, and adverse effects. Propensity score matching (PSM) was used to adjust the degree of infection before medication between the MT and CT groups. Univariate comparisons were performed using the chi-squared test for qualitative variables and Student's t-test or the Mann-Whitney U-test for continuous variables, as appropriate. Multivariate logistic regression analysis was performed to examine the relationship between antimicrobial treatments and mortality during hospitalization. The paired samples Wilcoxon test was used to compare the parameters before and after medication.

RESULTS

In total, 291 patients were included in the final analysis: 128 in MT group and 163 in CT group. Mortality rate was 6.25% in the MT group and 6.13% in the CT group (P = 0.97). Multivariate logistic regression model showed that carbapenem-resistant organisms (OR: 4.35, 95% CI: 2.36 ~ 61.70) and age > 65 (OR: 1.32, 95% CI:1.19 ~ 3.01) were independent risk factors for death. CT group had a shorter defervescence time (P < 0.05), with less likelihood of relapse (P < 0.05) but had a more significant effect on activated partial thromboplastin and prothrombin time.

CONCLUSIONS

Tigecycline plus β-lactam wasn't superior to tigecycline monotherapy for the treatment of non-critically ill patients with intra-abdominal infection. But for advanced age patients with cancer, tigecycline combination therapy maybe a better choice in terms of mortality.

An Overview of Cefiderocol's Therapeutic Potential and Underlying Resistance Mechanisms

Antimicrobial resistance continues to increase globally and treatment of difficult-to-treat (DTT) infections, mostly associated with carbapenem-resistant (CR) Pseudomonas aeruginosa, CR Acinetobacter baumannii, and CR- and third-generation-cephalosporins-resistant Enterobacterales remains a challenge for the clinician. The recent approval of cefiderocol has broaden the armamentarium for the treatment of patients with DTT infections. Cefiderocol is a siderophore cephalosporin that has shown excellent antibacterial activity, in part due to its innovative way of cell permeation. It is relatively stable compared to most commonly found carbapenamases. However, some resistant mechanisms to cefiderocol have already been identified and reduced susceptibility has developed during patient treatment, highlighting that the clinical use of cefiderocol must be rational. In this review, we summarize the current available treatments against the former resistant bacteria, and we revise and discuss the mechanism of action of cefiderocol, underlying the biological function of siderophores, the therapeutic potential of cefiderocol, and the mechanisms of resistance reported so far.

The tigecycline resistance gene tetX has an expensive fitness cost based on increased outer membrane permeability and metabolic burden in Escherichia coli

Livestock-derived tetX-positive Escherichia coli with tigecycline resistance poses a serious risk to public health. Fitness costs, antibiotic residues, and other tetracycline resistance genes (TRGs) are fundamental in determining the spread of tetX in the environment, but there is a lack of relevant studies. The results of this study showed that both tetO and tetX resulted in reduction in growth and an increased in the metabolic burden of E. coli, but the presence of doxycycline reversed this phenomenon. Moreover, the protection of E. coli growth and metabolism by tetO was superior to that of tetX in the presence of doxycycline, resulting in a much lower competitiveness of tetX-carrying E. coli than tetO-carrying E. coli. The results of RNA-seq showed that the increase in outer membrane proteins (ompC, ompF and ompT) of tetX-carrying E. coli resulted in increased membrane permeability and biofilm formation, which is an important reason for fitness costs. Overall, the increased membrane permeability and metabolic burden of E. coli is the mechanistic basis for the high fitness cost of tetX, and the spread of tetO may limit the spread of tetX. This study provides new insights into the rational use of tetracycline antibiotics to control the spread of tetX.

Ertapenem-Induced Neurotoxicity: A Literature Review of Clinical Characteristics and Treatment Outcomes

Background

Neurotoxicity is a rare adverse event for ertapenem. Given the limited evidence, large patient data are needed to aid in the identification and management of this fatal complication. Aim of the review, we summarize the characteristics, risk factors, and treatment of ertapenem-induced neurotoxicity.

Methods

Pubmed, Web of Science, Embase, Cochrane library, Wanfang, CNKI, China VIP database were searched up from 31 October 2001 to 31 December 2022. All articles concerning neurotoxicity induced by ertapenem were included. The retrieved articles were screened by two experienced clinicians by reading the titles, abstracts, and full texts.

Results

A total of 66 patients were included, with a median age of 71.5 years (range 40-92), of whom 45 (68.2%) were male. Twelve patients (18.2%) received irrational doses (exceeding the recommended dose), and 30 patients (45.5%) had chronic renal insufficiency. The median time to symptom onset was 5 (range 1-14). Epileptiform seizures (42.4%), visual hallucinations (36.4%), altered mental status (25.8%), and confusion (22.7%) were the most common symptoms of ertapenem-induced neurotoxicity. Of the 29 patients with reported albumin levels, 25 had serum albumin <3.5 g/dl. Ertapenem was discontinued in 95.5% of patients, and 90.9% recovered completely. Median time to symptom recovery was 7 days (range 1-42) after intervention including antiepileptic administration, or hemodialysis.

Conclusion

Neurotoxicity is a rare adverse event for ertapenem, especially in patients with advanced age, renal insufficiency, pre-existing neurological disease, and hypoalbuminemia. This adverse reaction usually resolves with medication interruption, or antiepileptic administration and hemodialysis.

Comparison of bleeding risk and hypofibrinogenemia-associated risk factors between tigecycline with cefoperazone/sulbactam therapy and other tigecycline-based combination therapies

Background: Tigecycline and cefoperazone/sulbactam can cause coagulation disorders; tigecycline may also lead to hypofibrinogenemia, raising safety concerns. This study aimed to investigate whether tigecycline plus cefoperazone/sulbactam increases the risk of bleeding compared with other tigecycline-based combination therapies and identify risk factors for tigecycline-associated hypofibrinogenemia. Methods: In this multi-method, multicenter, retrospective study, coagulation and other baseline variables were compared using a cohort study, and risk factors for hypofibrinogenemia using a case-control study. Results: The 451 enrolled participants were divided into three group: tigecycline plus cefoperazone/sulbactam (Group A, 193 patients), tigecycline plus carbapenems (Group B, 200 patients) and tigecycline plus β-lactams without N-methylthio-tetrazole (NMTT) side chains (Group C, 58 patients). Activated partial thromboplastin time and prothrombin time were prolonged, and fibrinogen declined for all patients after tigecycline-based medication (all p < 0.05). Prothrombin time in Group B was significantly longer than in other groups (p < 0.05), but there were no significant differences in bleeding events between the three groups (p = 0.845). Age greater than 80 years (OR: 2.85, 95% CI: 1.07-7.60), treatment duration (OR: 1.29, 95% CI: 1.19-1.41), daily dose (OR: 2.6, 95% CI: 1.29-5.25), total bilirubin (OR: 1.01, 95% CI: 1.01-1.02) and basal fibrinogen (OR: 1.32, 95% CI: 1.14-1.63) were independent risk factors of hypofibrinogenemia. The optimal cut-off for treatment course was 6 days for high-dose and 11 days for low-dose. Conclusion: Tigecycline plus cefoperazone/sulbactam did not increase the risk of bleeding compared with tigecycline plus carbapenem, or tigecycline plus β-lactam antibiotics without NMTT-side-chains. Coagulation function should be closely monitored in patients receiving tigecycline treatment.

In vitro Synergistic Activity of Ceftazidime-Avibactam in Combination with Aztreonam or Meropenem Against Clinical Enterobacterales Producing blaKPC or blaNDM

Background

It is often challenging to select appropriate combination therapies to treat infections caused by carbapenem-resistant Enterobacterales (CRE) with high-level resistance to carbapenem.

Methods

We investigated the in vitro synergistic activity of ceftazidime-avibactam-, polymyxin- or tigecycline-, and meropenem-based combinations using checkerboard assays against 16 CRE including Klebsiella pneumoniae carrying bla_KPC-2 (CR1-bla_KPC-2) and Enterobacter cloacae carrying bla_NDM-1 (CR2-bla_NDM-1) with meropenem MICs ≥128 mg/L. Time-kill assays were used to observe synergistic bactericidal activity.

Results

Meropenem in combination with ertapenem, amikacin, tigecycline or polymyxin B, and tigecycline plus ceftazidime-avibactam showed weak synergistic activities against CR1-bla_KPC-2 and CR2-bla_NDM-1. Polymyxin B combined with tigecycline or ceftazidime-avibactam, and ceftazidime-avibactam plus amikacin showed synergistic effects against two tigecycline-non-susceptible KPC-producers or three ceftazidime-avibactam-resistant NDM-producer, and 50% (5/10) of strains with amikacin MICs ≥4096 mg/L, respectively. Synergistic interactions of ceftazidime-avibactam plus aztreonam or meropenem in checkerboard assays were measured for 100% (16/16) and 93.8% (15/16) of strains, respectively. The time-kill assay further verified that the ceftazidime-avibactam combination had the potential to restore aztreonam susceptibility and reduced meropenem MICs to 8 mg/L.

Conclusion

Ceftazidime-avibactam plus aztreonam or meropenem could be an effective strategy for treating CRE infections, particularly those with high-level resistance to carbapenems and/or ceftazidime-avibactam.

Molecular characteristics of carbapenem-resistant gram-negative bacilli in pediatric patients in China

BACKGROUND

Carbapenem-resistant gram-negative bacilli (CR-GNB) have been increasingly reported in China. However, dynamic monitoring data on molecular epidemiology of CR-GNB are limited in pediatric patients.

RESULTS

300 CR-GNB isolates (200 Carbapenem-resistant K. pneumoniae (CRKP), 50 carbapenem-resistant A.baumannii (CRAB) and 50 carbapenem-resistant P. aeruginosa (CRPA)) were investigated. The predominant carbapenemase gene was blaNDM-1 (73%) and blaKPC-2 (65%) in neonates and non-neonates. Meanwhile, the predominant STs were ST11 (54%) in neonates and ST17 (27.0%) and ST278 (20.0%) in non-neonates. Notably, a shift in the dominant sequence type of CRKP infections from ST17 /ST278-NDM-1 to ST11-KPC-2 was observed during the years 2017-2021 and KPC-KP showed relatively higher resistance to aminoglycosides and quinolones than NDM-KP.BlaOXA-23 was isolated from all the CRAB isolates while only one isolate expressing blaBIC and 2 isolates expressing blaVIM-2 were found in CRPA isolates. ST195 (22.0%) and ST244 (24.0%) were the most common in CRAB and CRPA isolates and all the STs of CRAB belonged to CC92 while CRPA presents ST types with diversity distribution.

CONCLUSION

CRKP showed different molecular phenotypes in neonates and non-neonates and was changing dynamically and high-risk clone of ST11 KPC-KP should be paid more attention. Most CRKP and CRAB strains shared the same CCs, suggesting that intrahospital transmission may occur, and large-scale screening and more effective measures are urgently needed.

Antibiotic stewardship in the ICU: time to shift into overdrive

Antibiotic resistance is a major health problem and will be probably one of the leading causes of deaths in the coming years. One of the most effective ways to fight against resistance is to decrease antibiotic consumption. Intensive care units (ICUs) are places where antibiotics are widely prescribed, and where multidrug-resistant pathogens are frequently encountered. However, ICU physicians may have opportunities to decrease antibiotics consumption and to apply antimicrobial stewardship programs. The main measures that may be implemented include refraining from immediate prescription of antibiotics when infection is suspected (except in patients with shock, where immediate administration of antibiotics is essential); limiting empiric broad-spectrum antibiotics (including anti-MRSA antibiotics) in patients without risk factors for multidrug-resistant pathogens; switching to monotherapy instead of combination therapy and narrowing spectrum when culture and susceptibility tests results are available; limiting the use of carbapenems to extended-spectrum beta-lactamase-producing Enterobacteriaceae, and new beta-lactams to difficult-to-treat pathogen (when these news beta-lactams are the only available option); and shortening the duration of antimicrobial treatment, the use of procalcitonin being one tool to attain this goal. Antimicrobial stewardship programs should combine these measures rather than applying a single one. ICUs and ICU physicians should be at the frontline for developing antimicrobial stewardship programs.

The PEST (Pathology, Epidemiology, Severity, Treatment) approach to optimizing antimicrobial therapy

BACKGROUND

Selecting an empiric antimicrobial regimen can be difficult for early learners and misuse of antibiotics can lead to adverse events and antimicrobial resistance. There have been few interventions that have focused on improving antibiotic decision making, as a form of therapeutic reasoning, for post-graduate trainees. We describe here an approach to aid internal medicine interns in their therapeutic reasoning, particularly when it comes to diagnosing and empirically treating infections.

METHODS

The PEST (pathology, epidemiology, severity, treatment) model was created as a four-step approach to therapeutic reasoning and choosing an appropriate antimicrobial regimen for a given infectious disease syndrome. In February 2020, we conducted two independent teaching sessions for interns on the PEST approach. We assessed pre-and post-teaching responses to five clinical vignette-based questions. Results were presented as a percentage of interns who chose an appropriate antibiotic and provided sufficient therapeutic reasoning as defined by using at least three out of the four PEST criteria. Statistical analysis occurred via Fischer's exact test to determine the level of statistical significance between responses.

RESULTS

Twenty-seven interns participated in the activity. At baseline, several interns had incorporated aspects of the PEST approach in their pre-teaching responses. Ten interns commented on the usefulness of such a systematic approach. While there was no statistically significant difference in antibiotic selection, the teaching session demonstrated a trend towards significance in improving therapeutic reasoning as defined by the PEST strategy.

CONCLUSION

Our results suggested an improvement in using a structured cognitive tool such as the PEST approach to reinforce therapeutic reasoning, but the method did little to improve antibiotic selection. Some interns used select "PEST" concepts prior to the intervention suggesting that the PEST approach may enhance prior knowledge or clinical reasoning skills. Continued incorporation of the PEST approach using a case-based framework may solidify conceptual and practical knowledge of antimicrobial selection. Further studies are needed to assess the impact of such teaching interventions.

Treatment options for infections caused by multidrug-resistant Gram-negative bacteria: a guide to good clinical practice

The rapid emergence of multidrug-resistant Gram-negative bacterial infections necessitates the development of new treatments or the repurposing of available antibiotics. Here, treatment options for treatment of these infections, recent guidelines and evidence are reviewed. Studies that included treatment options for infections caused by multidrug-resistant Gram-negative bacteria (Enterobacterales and nonfermenters), as well as extended-spectrum β-lactamase-producing and carbapenem-resistant bacteria, were considered. Potential agents for the treatment of these infections, considering type of microorganism, mechanism of resistant, source and severity of infection as well as pharmacotherapy considerations, are summarized.

Antimicrobial Resistance in Romania: Updates on Gram-Negative ESCAPE Pathogens in the Clinical, Veterinary, and Aquatic Sectors

Multidrug-resistant Gram-negative bacteria such as Acinetobacter baumannii, Pseudomonas aeruginosa, and members of the Enterobacterales order are a challenging multi-sectorial and global threat, being listed by the WHO in the priority list of pathogens requiring the urgent discovery and development of therapeutic strategies. We present here an overview of the antibiotic resistance profiles and epidemiology of Gram-negative pathogens listed in the ESCAPE group circulating in Romania. The review starts with a discussion of the mechanisms and clinical significance of Gram-negative bacteria, the most frequent genetic determinants of resistance, and then summarizes and discusses the epidemiological studies reported for A. baumannii, P. aeruginosa, and Enterobacterales-resistant strains circulating in Romania, both in hospital and veterinary settings and mirrored in the aquatic environment. The Romanian landscape of Gram-negative pathogens included in the ESCAPE list reveals that all significant, clinically relevant, globally spread antibiotic resistance genes and carrying platforms are well established in different geographical areas of Romania and have already been disseminated beyond clinical settings.

Antimicrobial Stewardship on Patients with Neutropenia: A Narrative Review Commissioned by Microorganisms

The emergence of antibiotic resistance poses a global health threat. High-risk patients such as those with neutropenia are particularly vulnerable to opportunistic infections, sepsis, and multidrug-resistant infections, and clinical outcomes remain the primary concern. Antimicrobial stewardship (AMS) programs should mainly focus on optimizing antibiotic use, decreasing adverse effects, and improving patient outcomes. There is a limited number of published studies assessing the impact of AMS programs on patients with neutropenia, where early appropriate antibiotic choice can be the difference between life and death. This narrative review updates the current advances in strategies of AMS for bacterial infections among high-risk patients with neutropenia. Diagnosis, drug, dose, duration, and de-escalation (5D) are the core variables among AMS strategies. Altered volumes of distribution can make standard dose regimens inadequate, and developing skills towards a personalized approach represents a major advance in therapy. Intensivists should partner antibiotic stewardship programs to improve patient care. Assembling multidisciplinary teams with trained and dedicated professionals for AMS is a priority.