Epidemiology of carbapenem-resistant Gram-negative infections globally:

Prevalence and molecular epidemiology of carbapenemase-producing Enterobacterales isolated from dog and cat faeces submitted to veterinary laboratories in the USA

AIMS

To estimate the prevalence of carbapenemase-producing Enterobacterales (CPE) carriage among pets using faecal specimens submitted to veterinary diagnostic laboratories throughout the US. A secondary aim was to employ whole-genome sequencing (WGS) to characterize isolates of CPE from companion animals and compare them to publicly available CPE genomes.

METHODS AND RESULTS

To estimate the prevalence of CPE in companion animals in the USA, a multicenter surveillance study including 8 different veterinary diagnostic laboratories from across the USA was conducted. Briefly, remnant faecal specimens from dogs and cats were screened using two selective agar plates (CHROMID Carba and MacConkey with 1 mg/L cefotaxime and 0.125 mg/L meropenem) and presumptive CPE isolates screened by the modified carbapenemase inactivation method for carbapenemase production. A total of 2393 specimens were screened and yielded 196 isolates for carbapenemase screening. A total of 5 isolates from 4 dogs and 1 cat at 3 different veterinary diagnostic laboratories were confirmed to produce a carbapenemase (0.21%). Whole-genome sequencing (WGS) revealed two E. coli (ST167) isolates that both produced an NDM-5 carbapenemase, two Enterobacter hormaechei (ST171) isolates that produced an NDM-5 carbapenemase and a KPC-4 carbapenemase respectively and one Klebsiella oxytoca (ST199) that produced an Oxa-48-type carbapenemase. Both E. coli isolates were found to be within at least 22 SNPs of previously characterized canine and human CPE isolates.

CONCLUSIONS

This study demonstrates that the prevalence of CPE among companion animals is relatively low (0.21%) but that given the genetic relatedness of animal isolates to human isolates, additional surveillance is needed.

Tackling Carbapenem Resistance and the Imperative for One Health Strategies-Insights from the Portuguese Perspective

Carbapenemases, a class of enzymes specialized in the hydrolysis of carbapenems, represent a significant threat to global public health. These enzymes are classified into different Ambler's classes based on their active sites, categorized into classes A, D, and B. Among the most prevalent types are IMI/NMC-A, KPC, VIM, IMP, and OXA-48, commonly associated with pathogenic species such as Acinetobacter baumannii, Klebsiella pneumoniae, and Pseudomonas aeruginosa. The emergence and dissemination of carbapenemase-producing bacteria have raised substantial concerns due to their ability to infect humans and animals (both companion and food-producing) and their presence in environmental reservoirs. Adopting a holistic One Health approach, concerted efforts have been directed toward devising comprehensive strategies to mitigate the impact of antimicrobial resistance dissemination. This entails collaborative interventions, highlighting proactive measures by global organizations like the World Health Organization, the Center for Disease Control and Prevention, and the Food and Agriculture Organization. By synthesizing the evolving landscape of carbapenemase epidemiology in Portugal and tracing the trajectory from initial isolated cases to contemporary reports, this review highlights key factors driving antibiotic resistance, such as antimicrobial use and healthcare practices, and underscores the imperative for sustained vigilance, interdisciplinary collaboration, and innovative interventions to curb the escalating threat posed by antibiotic-resistant pathogens. Finally, it discusses potential alternatives and innovations aimed at tackling carbapenemase-mediated antibiotic resistance, including new therapies, enhanced surveillance, and public awareness campaigns.

Molecular characterization and descriptive analysis of carbapenemase-producing Gram-negative rod infections in Bogota, Colombia

In this study, the genetic differences and clinical impact of the carbapenemase-encoding genes among the community and healthcare-acquired infections were assessed. This retrospective, multicenter cohort study was conducted in Colombia and included patients infected with carbapenem-resistant Gram-negative rods between 2017 and 2021. Carbapenem resistance was identified by Vitek, and carbapenemase-encoding genes were identified by whole-genome sequencing (WGS) to classify the alleles and sequence types (STs). Descriptive statistics were used to determine the association of any pathogen or gene with clinical outcomes. A total of 248 patients were included, of which only 0.8% (2/248) had community-acquired infections. Regarding the identified bacteria, the most prevalent pathogens were Pseudomonas aeruginosa and Klebsiella pneumoniae. In the WGS analysis, 228 isolates passed all the quality criteria and were analyzed. The principal carbapenemase-encoding gene was blaKPC, specifically blaKPC-2 [38.6% (88/228)] and blaKPC-3 [36.4% (83/228)]. These were frequently detected in co-concurrence with blaVIM-2 and blaNDM-1 in healthcare-acquired infections. Notably, the only identified allele among community-acquired infections was blaKPC-3 [50.0% (1/2)]. In reference to the STs, 78 were identified, of which Pseudomonas aeruginosa ST111 was mainly related to blaKPC-3. Klebsiella pneumoniae ST512, ST258, ST14, and ST1082 were exclusively associated with blaKPC-3. Finally, no particular carbapenemase-encoding gene was associated with worse clinical outcomes. The most identified genes in carbapenemase-producing Gram-negative rods were blaKPC-2 and blaKPC-3, both related to gene co-occurrence and diverse STs in the healthcare environment. Patients had several systemic complications and poor clinical outcomes that were not associated with a particular gene.IMPORTANCEAntimicrobial resistance is a pandemic and a worldwide public health problem, especially carbapenem resistance in low- and middle-income countries. Limited data regarding the molecular characteristics and clinical outcomes of patients infected with these bacteria are available. Thus, our study described the carbapenemase-encoding genes among community- and healthcare-acquired infections. Notably, the co-occurrence of carbapenemase-encoding genes was frequently identified. We also found 78 distinct sequence types, of which two were novel Pseudomonas aeruginosa, which could represent challenges in treating these infections. Our study shows that in low and middle-income countries, such as Colombia, the burden of carbapenem resistance in Gram-negative rods is a concern for public health, and regardless of the allele, these infections are associated with poor clinical outcomes. Thus, studies assessing local epidemiology, prevention strategies (including trials), and underpinning genetic mechanisms are urgently needed, especially in low and middle-income countries.

Intraventricular or intrathecal polymyxin B for treatment of post-neurosurgical intracranial infection caused by carbapenem-resistant gram-negative bacteria: a 8-year retrospective study

PURPOSE

Post-neurosurgical intracranial infection caused by carbapenem-resistant gram-negative bacteria (CRGNB) is a life-threatening complication. This study aimed to assess the current practices and clinical outcomes of intravenous (IV) combined with intraventricular (IVT)/intrathecal (ITH) polymyxin B in treating CRGNB intracranial infection.

METHODS

A retrospective study was conducted on patients with post-neurosurgical intracranial infection due to CRGNB from January 2013 to December 2020. Clinical characteristics and treatment outcomes were collected and described. Kaplan-Meier survival and multivariate logistic regression analyses were performed.

RESULTS

The study included 114 patients, of which 72 received systemic antimicrobial therapy combined with IVT/ITH polymyxin B, and 42 received IV administration alone. Most infections were caused by carbapenem-resistant Acinetobacter baumannii (CRAB, 63.2%), followed by carbapenem-resistant Klebsiella pneumoniae (CRKP, 31.6%). Compared with the IV group, the IVT/ITH group had a higher cerebrospinal fluid (CSF) sterilization rate in 7 days (p < 0.001) and lower 30-day mortality (p = 0.032). In the IVT/ITH group, patients with CRKP infection had a higher initial fever (p = 0.014), higher incidence of bloodstream infection (p = 0.040), lower CSF sterilization in 7 days (p < 0.001), and higher 30-day mortality (p = 0.005) than those with CRAB infection. Multivariate logistic regression analysis revealed that the duration of IVT/ITH polymyxin B (p = 0.021) was independently associated with 30-day mortality.

CONCLUSIONS

Intravenous combined with IVT/ITH polymyxin B increased CSF microbiological eradication and improved clinical outcomes. CRKP intracranial infections may lead to more difficult treatment and thus warrant attention and further optimized treatment.

Ceftazidime-Avibactam resistance in clinical isolates of carbapenem-resistant Klebsiella pneumoniae: A phenotypic and genotypic analysis

OBJECTIVE

To find the prevalence of Ceftazidime-Avibactam (CAZ-AVI) resistant Klebsiella pneumoniae in clinical isolates and to determine the genes responsible for Ceftazidime-Avibactam resistance using PCR.

METHODS

A total of 89 carbapenem resistant Klebsiella pneumoniae from various clinical samples were included in the study. CAZ-AVI resistance was tested using E-test. CAZ-AVI resistant strains were subjected to conventional PCR for detection of carbapenamase genes blaNDM- 1, blaOXA-48, blaVIM, blaIMP, blaKPC.

RESULTS

Of the 89 isolates screened for CAZ-AVI resistance, 45(50.5%) isolates were found to be resistant. 42 isolates were subjected to PCR for detection of β lactamase genes.34 isolates were positive for blaNDM-1 and all 42 isolates were positive for blaOXA-48. Co-expression of NDM-1 and OXA-48 was seen in 34 isolates. Sensitivity of mCIM test to identify a carbapenamse compared to PCR was 61.9%. Sensitivity of eCIM test to identify NDM-1 was 80%.

CONCLUSION

CAZ-AVI was effective in vitro in 49.4% of the isolates. Indicating that CAZ-AVI is a promising addition to antibiotics against CRE as well as a carbapenem sparing drug in ESBL producing organisms. β-Lactamase-related mutations are the main mechanism leading to CAZ-AVI resistance.

The impact of colonization by multidrug resistant bacteria on graft survival, risk of infection, and mortality in recipients of solid organ transplant: systematic review and meta-analysis

BACKGROUND

The Global increase in colonization by multidrug-resistant (MDR) bacteria poses a significant concern. The precise impact of MDR colonization in solid organ transplant recipients (SOTR) remains not well established.

OBJECTIVES

To assess the impact of MDR colonization on SOTR's mortality, infection, or graft loss.

METHODS AND DATA SOURCES

Data from PROSPERO, OVID Medline, OVID EMBASE, Wiley Cochrane Library, ProQuest Dissertations, Theses Global, and SCOPUS were systematically reviewed, spanning from inception until 20 March 2023. The study protocol was registered with PROSPERO (CRD42022290011) and followed the PRISMA guidelines. STUDY ELIGIBILITY CRITERIA, PARTICIPANTS, INTERVENTIONS, AND ASSESSMENT OF RISK OF BIAS: Cohorts and case-control studies that reported on adult SOTR colonized by Methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE), extended-spectrum β-lactamase (ESBL) or carbapenem-resistant Enterobacteriaceae. (CRE), or MDR-pseudomonas, and compared to noncolonized, were included. Two reviewers assessed eligibility, conducted a risk of bias evaluation using the Newcastle-Ottawa Scale, and rated certainty of evidence using the GRADE approach.

METHODS OF DATA SYNTHESIS

We employed RevMan for a meta-analysis, using random-effects models to compute pooled odds ratios (OR) and 95% confidence intervals (CI). Statistical heterogeneity was determined using the I2 statistic.

RESULTS

15,202 SOTR (33 cohort, six case-control studies) were included, where liver transplant and VRE colonization (25 and 14 studies) were predominant. MDR colonization significantly increased posttransplant 1-year mortality (OR, 2.35; 95% CI, 1.63-3.38) and mixed infections (OR, 10.74; 95% CI, 7.56-12.26) across transplant types (p < 0.001 and I2 = 58%), but no detected impact on graft loss (p 0.41, I2 = 0). Subgroup analysis indicated a higher association between CRE or ESBL colonization with outcomes (CRE: death OR, 3.94; mixed infections OR, 24.8; ESBL: mixed infections OR, 10.3; no mortality data) compared to MRSA (Death: OR, 2.25; mixed infection: OR, 7.75) or VRE colonization (Death: p 0.20, mixed infections: OR, 5.71).

CONCLUSIONS

MDR colonization in SOTR, particularly CRE, is associated with increased mortality. Despite the low certainty of the evidence, actions to prevent MDR colonization in transplant candidates are warranted.

Carriage of third-generation cephalosporin-resistant and carbapenem-resistant Enterobacterales among children in sub-Saharan Africa: a systematic review and meta-analysis

Background

The increasing resistance of Enterobacterales to third-generation cephalosporins and carbapenems in sub-Saharan Africa (SSA) is a major public health concern. We did a systematic review and meta-analysis of studies to estimate the carriage prevalence of Enterobacterales not susceptible to third-generation cephalosporins or carbapenems among paediatric populations in SSA.

Methods

We performed a systematic literature review and meta-analysis of cross-sectional and cohort studies to estimate the prevalence of childhood (0-18 years old) carriage of extended-spectrum cephalosporin-resistant Enterobacterales (ESCR-E) or carbapenem-resistant Enterobacterales (CRE) in SSA. Medline, EMBASE and the Cochrane Library were searched for studies published from 1 January 2005 to 1 June 2022. Studies with <10 occurrences per bacteria, case reports, and meta-analyses were excluded. Quality and risk of bias were assessed using the Newcastle-Ottawa scale. Meta-analyses of prevalences and odds ratios were calculated using generalised linear mixed-effects models. Heterogeneity was assessed using I2 statistics. The protocol is available on PROSPERO (CRD42021260157).

Findings

Of 1111 studies examined, 40 met our inclusion criteria, reporting on the carriage prevalence of Enterobacterales in 9408 children. The pooled carriage prevalence of ESCR-E was 32.2% (95% CI: 25.2%-40.2%). Between-study heterogeneity was high (I2 = 96%). The main sources of bias pertained to participant selection and the heterogeneity of the microbiological specimens. Carriage proportions were higher among sick children than healthy ones (35.7% vs 16.9%). The pooled proportion of nosocomial acquisition was 53.8% (95% CI: 32.1%-74.1%) among the 922 children without ESCR-E carriage at hospital admission. The pooled odds ratio of ESCR-E carriage after antibiotic treatment within the previous 3 months was 3.20 (95% CI: 2.10-4.88). The proportion of pooled carbapenem-resistant for Enterobacterales was 3.6% (95% CI: 0.7%-16.4%).

Interpretation

This study suggests that ESCR-E carriage among children in SSA is frequent. Microbiology capacity and infection control must be scaled-up to reduce the spread of those multidrug-resistant microorganisms.

Funding

There was no funding source for this study.

Carbapenem-resistant Enterobacterales among hospitalized patients in Cape Town, South Africa: clinical and microbiological epidemiology

Background

Carbapenem-resistant Enterobacterales (CRE) are a substantial problem in Cape Town. CRE epidemiology is largely unknown and mortality remains high.

Objectives

To describe and characterize the clinical and microbiological epidemiology of CRE within Cape Town hospitals to better inform therapy with regard to current and novel antibiotics, as well as improve antimicrobial stewardship (AMS), and infection prevention and control (IPC).

Methods

This prospective, multicentre study performed between 1 November 2020 and 30 November 2022, across three public and three private hospitals included hospitalized participants with CRE from clinical cultures. Participant demographics, clinical information and microbiology results were collected and analysed.

Results

Ninety percent of participants were from public hospitals. The age distribution ranged from 7 days to 88 years. Notable risk factors for CRE infection included recent exposure to antibiotics, medical devices and surgery. The most prevalent species was Klebsiella pneumoniae. However, a higher proportion of Serratia marcescens compared with previous reports was identified. The detected carbapenemases were blaOXA-48-like (80%) and blaNDM (11%). With the exception of amikacin (63%), tigecycline (65%), colistin (95%) and ceftazidime/avibactam (87%), susceptibility to antibiotics was low.

Conclusions

This study identified common risk factors for CRE infection and generated a description of carbapenemase enzymes, species distribution and antibiograms, enabling a better understanding of CRE epidemiology. This provides insights into transmission patterns and resistance determinants of CREs, beneficial to informing data-driven regional patient management, AMS and IPC strategies.

Epidemiology, Clinical, and Microbiological Characteristics of Multidrug-Resistant Gram-Negative Bacteremia in Qatar

Antimicrobial resistance is a global healthcare threat with significant clinical and economic consequences peaking at secondary and tertiary care hospitals where multidrug-resistant Gram-negative bacteria (MDR GNB) lead to poor outcomes. A prospective study was conducted between January and December 2019 for all invasive bloodstream infections (BSIs) secondary to MDR GNB in Qatar identified during routine microbiological service to examine their clinical, microbiological, and genomic characteristics. Out of 3238 episodes of GNB BSIs, the prevalence of MDR GNB was 13% (429/3238). The predominant MDR pathogens were Escherichia coli (62.7%), Klebsiella pneumoniae (20.4%), Salmonella species (6.6%), and Pseudomonas aeruginosa (5.3%), while out of 245 clinically evaluated patients, the majority were adult males, with the elderly constituting almost one-third of the cohort and with highest observed risk for prolonged hospital stays. The risk factors identified included multiple comorbidities, recent healthcare contact, previous antimicrobial therapy, and admission to critical care. The in-hospital mortality rate was recorded at 25.7%, associated with multiple comorbidities, admission to critical care, and the acquisition of MDR Pseudomonas aeruginosa. Resistant pathogens demonstrated high levels of antimicrobial resistance but noticeable susceptibility to amikacin and carbapenems. Genomic analysis revealed that Escherichia coli ST131 and Salmonella enterica ST1 were the predominant clones not observed with other pathogens.

Phenotypic and Genotypic Characterization of Pan-Drug-Resistant Klebsiella pneumoniae Isolated in Qatar

In secondary healthcare, carbapenem-resistant Enterobacterales (CREs), such as those observed in Klebsiella pneumoniae, are a global public health priority with significant clinical outcomes. In this study, we described the clinical, phenotypic, and genotypic characteristics of three pan-drug-resistant (PDR) isolates that demonstrated extended resistance to conventional and novel antimicrobials. All patients had risk factors for the acquisition of multidrug-resistant organisms, while microbiological susceptibility testing showed resistance to all conventional antimicrobials. Advanced susceptibility testing demonstrated resistance to broad agents, such as ceftazidime-avibactam, ceftolozane-tazobactam, and meropenem-vaborbactam. Nevertheless, all isolates were susceptible to cefiderocol, suggested as one of the novel antimicrobials that demonstrated potent in vitro activity against resistant Gram-negative bacteria, including CREs, pointing toward its potential therapeutic role for PDR pathogens. Expanded genomic studies revealed multiple antimicrobial-resistant genes (ARGs), including blaNMD-5 and blaOXA derivative types, as well as a mutated outer membrane porin protein (OmpK37).

Clinical success of anti-infective combination therapy compare to monotherapy in patients with carbapenem-resistant Pseudomonas aeruginosa infection: a 10-years retrospective study

BACKGROUND

Carbapenem-resistant Pseudomonas aeruginosa (CRPA) infection has become a major public health concern. The recommendations for monotherapy and combination therapy in the current guidelines lack sufficient evidence to support them. The primary objective of this study is to determine the effectiveness of anti-Infective combination therapy compared to monotherapy in achieving clinical success in patients with CRPA infection and risk factors of clinical failure of monotherapy.

METHODS

A retrospective study from Medical Information Mart for Intensive Care IV (MIMIC-IV) was conducted. We included adults with infections caused by CRPA. The outcomes of this study were clinical success, complete clinical success, and 28-day all-cause mortality.

RESULTS

A total of 279 subjects were finally enrolled. The rate of clinical success for combination therapy was higher than that for monotherapy (73.1% versus 60.4%, p=0.028). Compared to clinical failure patients, patients in the clinical success group were more likely to die within 28 days after CRPA was found (48.3% versus 3.6%, p<0.001). In a multivariate logistic regression analysis, monotherapy was found to be significantly correlated with clinical success (OR, 0.559, 95% CI, 0.321-0.976; p = 0.041).

CONCLUSION

Combination therapy is more effective for CRPA infection patients, especially those whose SOFA score is ≥ 2 or whose Charlson comorbidity index is ≥ 6.

Detection of rare carbapenemases in Enterobacterales-comparison of two colorimetric and three CIM-based carbapenemase assays

Rapid and reliable detection of carbapenemase-producing Enterobacterales (CPE) is crucial for prompt treatment and infection control. Most assays target the primary four enzymes (KPC, OXA-48-like, VIM, and NDM), often missing less common variants (e.g., GES, IMI, OXA-23, and OXA-58). Therefore, assays based on the hydrolysis of carbapenems are recommended in addition to differentiation tests such as PCR or immunochromatographic assays. The aim of this study was to compare the currently Clinical and Laboratory Standards Institute (CLSI)-recommended tests mCIM (modified carbapenem inactivation method) and Carba NP with new colorimetric tests (NitroSpeed-Carba NP) and novel variations of the carbapenem inactivation method (CIM) such as simplified CIM (sCIM) or modified zinc-supplemented CIM (mzCIM). The challenge collection included 205 clinical isolates, 139 CPE vs 66 non-CPE. Among all 205 isolates, the sensitivity/specificity of mCIM was 81.3%/98.5%, Carba NP 76.3%/100%, NitroSpeed-Carba NP 86.3%/78.8%, sCIM 100%/94%, and mzCIM 97.8%/98.5%. For rare carbapenemases (n = 48), the sensitivity of mzCIM (98.3%) and sCIM (100%) was higher than that of mCIM (60.4%), Carba NP (50%), or NitroSpeed-Carba NP (70.2%). Most indeterminate results occurred for mCIM (14.4%), Carba NP (8.2%), and sCIM (6.3%). The detection of rare carbapenemases remains challenging with the currently recommended assays. The CIM-based tests demonstrated superior sensitivity, with sCIM and mzCIM outperforming the currently recommended mCIM and Carba NP, especially among isolates with weakly hydrolyzing carbapenemases (e.g., OXA-23 and OXA-58). Although colorimetric assays provide more rapid results, laboratories have to be aware of the low sensitivity for rare carbapenemases. Both sCIM and the new mzCIM performed well, are cost-effective, and can easily be implemented in any laboratory.IMPORTANCEDetection of so-called rare carbapenemases (e.g., GES, IMI, OXA-23, and OXA-58) in Enterobacterales is challenging, and data on the performance of currently available assays are scarce. This study systematically assessed the performance of currently recommended and novel hydrolysis-based assays on a set of molecularly characterized isolates. It demonstrates that the currently recommended assays mCIM and Carba NP perform well on isolates producing common carbapenemases such as KPC, VIM, NDM, and OXA-48, but have only a moderate sensitivity in the detection of rare carbapenemases. In contrast, the newer CIM-based variants, sCIM and mzCIM, are equally capable of detecting frequent and uncommon carbapenemases. These assays could potentially help to improve our knowledge on the epidemiology of these "rare" enzymes.

Exploring the genetic basis of natural resistance to microcins

Enterobacteriaceae produce an arsenal of antimicrobial compounds including microcins, ribosomally produced antimicrobial peptides showing diverse structures and mechanisms of action. Microcins target close relatives of the producing strain to promote its survival. Their narrow spectrum of antibacterial activity makes them a promising alternative to conventional antibiotics, as it should decrease the probability of resistance dissemination and collateral damage to the host's microbiota. To assess the therapeutic potential of microcins, there is a need to understand the mechanisms of resistance to these molecules. In this study, we performed genomic analyses of the resistance to four microcins [microcin C, a nucleotide peptide; microcin J25, a lasso peptide; microcin B17, a linear azol(in)e-containing peptide; and microcin E492, a siderophore peptide] on a collection of 54 Enterobacteriaceae from three species: Escherichia coli, Salmonella enterica and Klebsiella pneumoniae. A gene-targeted analysis revealed that about half of the microcin-resistant strains presented mutations of genes involved in the microcin mechanism of action, especially those involved in their uptake (fhuA, fepA, cirA and ompF). A genome-wide association study did not reveal any significant correlations, yet relevant genetic elements were associated with microcin resistance. These were involved in stress responses, biofilm formation, transport systems and acquisition of immunity genes. Additionally, microcin-resistant strains exhibited several mutations within genes involved in specific metabolic pathways, especially for S. enterica and K. pneumoniae.

Emergence of OXA-48-producing hypervirulent Klebsiella pneumoniae strains in Taiwan

The OXA-48-producing hypervirulent Klebsiella pneumoniae (hvKP) strains were rarely reported. In this study, we characterized three carbapenem-resistant hvKP strains (KP2185, NCRE61, and KP2683-1) isolated from renal abscess, scrotal abscess, and blood samples in a Taiwan hospital. The three strains belonged to two different clones: ST23 K1 (KP2683-1) and ST11 KL64 (KP2185 and NCRE61). KP2683-1 exhibited the highest virulence in an in vivo model. Whole-genome sequencing analysis showed that KP2185 and NCRE61 acquired IncFIB type plasmids containing a set of virulence genes (iroBCDN, iucABCD, rmpA, rmpA2, and iutA), while KP2683-1 acquired an IncL type plasmid harboring blaOXA-48.

Intestinal carbapenem-resistant Klebsiella pneumoniae undergoes complex transcriptional reprogramming following immune activation

Carbapenem-resistant Klebsiella pneumoniae (CR-Kp) is a significant threat to public health worldwide. The primary reservoir for CR-Kp is the intestinal tract. There, the bacterium is usually present at low density but can bloom following antibiotic treatment, mostly in hospital settings. The impact of disturbances in the intestinal environment on the fitness, survival, expansion, and drug susceptibility of this pathogen is not well-understood, yet it may be relevant to devise strategies to tackle CR-Kp colonization and infection. Here, we adopted an in vivo model to examine the transcriptional adaptation of a CR-Kp clinical isolate to immune activation in the intestine. We report that as early as 6 hours following host treatment with anti-CD3 antibody, CR-Kp underwent rapid transcriptional changes including downregulation of genes involved in sugar utilization and amino acid biosynthesis and upregulation of genes involved in amino acid uptake and catabolism, antibiotic resistance, and stress response. In agreement with these findings, treatment increased the concentration of oxidative species and amino acids in the mouse intestine. Genes encoding for proteins containing the domain of unknown function (DUF) 1471 were strongly upregulated, however their deletion did not impair CR-Kp fitness in vivo upon immune activation. Transcription factor enrichment analysis identified the global regulator cAMP-Receptor Protein, CRP, as a potential orchestrator of the observed transcriptional signature. In keeping with the recognized role of CRP in regulating utilization of alternative carbon sources, crp deletion in CR-Kp resulted in strongly impaired gut colonization, although this effect was not amplified by immune activation. Thus, following intestinal colonization, which occurs in a CRP-dependent manner, CR-Kp can rapidly respond to immune cues by implementing a well-defined and complex transcriptional program whose direct relevance toward bacterial fitness warrants further investigation. Additional analyses utilizing this model may identify key factors to tackle CR-Kp colonization of the intestine.

Plasmids, a molecular cornerstone of antimicrobial resistance in the One Health era

Antimicrobial resistance (AMR) poses a substantial threat to human health. The widespread prevalence of AMR is, in part, due to the horizontal transfer of antibiotic resistance genes (ARGs), typically mediated by plasmids. Many of the plasmid-mediated resistance genes in pathogens originate from environmental, animal or human habitats. Despite evidence that plasmids mobilize ARGs between these habitats, we have a limited understanding of the ecological and evolutionary trajectories that facilitate the emergence of multidrug resistance (MDR) plasmids in clinical pathogens. One Health, a holistic framework, enables exploration of these knowledge gaps. In this Review, we provide an overview of how plasmids drive local and global AMR spread and link different habitats. We explore some of the emerging studies integrating an eco-evolutionary perspective, opening up a discussion about the factors that affect the ecology and evolution of plasmids in complex microbial communities. Specifically, we discuss how the emergence and persistence of MDR plasmids can be affected by varying selective conditions, spatial structure, environmental heterogeneity, temporal variation and coexistence with other members of the microbiome. These factors, along with others yet to be investigated, collectively determine the emergence and transfer of plasmid-mediated AMR within and between habitats at the local and global scale.

Interprofessional Therapeutic Drug Monitoring of Carbapenems Improves ICU Care and Guideline Adherence in Acute-on-Chronic Liver Failure

(1) Background: Acute-on-chronic liver failure (ACLF) is a severe, rapidly progressing disease in patients with liver cirrhosis. Meropenem is crucial for treating severe infections. Therapeutic drug monitoring (TDM) offers an effective means to control drug dosages, especially vital for bactericidal antibiotics like meropenem. We aimed to assess the outcomes of implementing TDM for meropenem using an innovative interprofessional approach in ACLF patients on a medical intensive care unit (ICU). (2) Methods: The retrospective study was conducted on a medical ICU. The outcomes of an interprofessional approach comprising physicians, hospital pharmacists, and staff nurses to TDM for meropenem in critically ill patients with ACLF were examined in 25 patients. Meropenem was administered continuously via an infusion pump after the application of an initial loading dose. TDM was performed weekly using high-performance liquid chromatography (HPLC). Meropenem serum levels, implementation of the recommendations of the interprofessional team, and meropenem consumption were analyzed. (3) Results: Initial TDM for meropenem showed a mean meropenem serum concentration of 20.9 ± 9.6 mg/L in the 25 analyzed patients. Of note, in the initial TDM, only 16.0% of the patients had meropenem serum concentrations within the respective target range, while 84.0% exceeded this range. Follow-up TDM showed serum concentrations of 15.2 ± 5.7 mg/L (9.0-24.6) in Week 2 and 11.9 ± 2.3 mg/L (10.2-13.5) in Week 3. In Week 2, 41.7% of the patients had meropenem serum concentrations that were within the respective target range, while 58.3% of the patients were above this range. In Week 3, 50% of the analyzed serum concentrations of meropenem were within the targeted range, and 50% were above the range. In total, 100% of the advice given by the interprofessional team regarding meropenem dosing or a change in antibiotic therapy was implemented. During the intervention period, the meropenem application density was 37.9 recommended daily doses (RDD)/100 patient days (PD), compared to 42.1 RDD/100 PD in the control period, representing a 10.0% decrease. (4) Conclusions: Our interprofessional approach to TDM significantly reduced meropenem dosing, with all the team's recommendations being implemented. This method not only improved patient safety but also considerably decreased the application density of meropenem.

The whole-genome molecular epidemiology of sequential isolates of Acinetobacter baumannii colonizing the rectum of patients in an adult intensive care unit of a tertiary hospital

IMPORTANCE

Acinetobacter baumannii is a multidrug-resistant nosocomial pathogen that colonizes and infects debilitated patients in the ICU. There is very little information on the genomic characteristics of colonizing strains. This information is important to understand the evolution of lineages of A. baumannii that develop resistance while patients receive antibiotic treatment in the ICU. Our study demonstrated different patterns of colonization of the rectum of ICU patients with different STs of A. baumannii while one ST colonized all patients. Some STs carried more antibiotic resistance genes compared to others. However, there was a correlation between ST and a particular resistance gene profile. Our results further elucidate the dynamics of enteric colonization of this opportunistic pathogen.

Carbapenem resistant Enterobacterales in the United Arab Emirates: a retrospective analysis from 2010 to 2021

Background

Carbapenem-resistant Enterobacterales (CRE) are spreading in the United Arab Emirates (UAE) where their dissemination is facilitated by international travel, trade, and tourism. The objective of this study is to describe the longitudinal changes of CRE as reported by the national AMR surveillance system of the UAE.

Methods

In this study, we retrospectively describe CRE isolated from 317 surveillance sites, including 87 hospitals and 230 centers/clinics from 2010 to 2021. The associated clinical, demographic, and microbiological characteristics are presented by relying on the UAE national AMR surveillance program. Data was analyzed using WHONET microbiology laboratory database software (http://www.whonet.org).

Results

A total of 14,593 carbapenem resistant Enterobacterales were analyzed, of which 48.1% were carbapenem resistant Klebsiella pneumoniae (CRKp), 25.1% carbapenem resistant Escherichia coli (CREc), and 26.8% represented 72 other carbapenem resistant species. Carbapenem resistant strains were mostly associated with adults and isolated from urine samples (36.9% of CRKp and 66.6% of CREc) followed by respiratory samples (26.95% for CRKp) and soft tissue samples (19.5% for CRKp). Over the studied period carbapenem resistance rates remained high, especially in K. pneumoniae, and in 2021 were equivalent to 67.6% for imipenem, 76.2% for meropenem, and 91.6% for ertapenem. Nevertheless, there was a statistically significant decreasing trend for imipenem and meropenem resistance in Klebsiella species (p < 0.01) while the decrease in ertapenem resistance was non-significant. Concerning E. coli, there was a statistically significant decreasing trend for meropenem and imipenem resistance over the 12 years, while ertapenem resistance increased significantly with 83.8% of E. coli exhibiting ertapenem resistance in 2021. Resistance rates to ceftazidime and cefotaxime remained higher than 90% (in 2021) for CRKp and cefotaxime rates increased to 90.5% in 2021 for CREc. Starting 2014, resistance to colistin and tigecycline was observed in carbapenem resistant Enterobacterales. CRE were associated with a higher mortality (RR: 6.3), admission to ICU (RR 3.9), and increased length of stay (LOS; 10 excess inpatient days per CRE case).

Conclusion

This study supports the need to monitor CRE in the UAE and draws attention to the significant increase of ertapenem resistance in E. coli. Future surveillance analysis should include a genetic description of carbapenem resistance to provide new strategies.

Antibiotic prophylaxis after 48 h postoperatively are not associated with decreased surgical site infections and other healthcare associated infections in pancreatic surgery patients: a retrospective cohort study

BACKGROUND

It is controversial whether antibiotic should be used prophylactically 48 h after pancreatic surgery. Hence, the association of antibiotic prophylaxis (AP) after 48 h postoperatively with the incidence of surgical site infections (SSIs) and other healthcare-associated infections (HAIs) in patients receiving pancreatic surgery was evaluated.

METHODS

A retrospective cohort analysis was performed on 1073 patients who underwent pancreatic surgery. These patients were categorized into the non-AP after 48 h postoperatively group (n = 963) and the AP after 48 h postoperatively group (n = 110) based on whether or not they obtained AP from 48 h to 30 days after surgery. Outcomes included SSIs and other HAIs.

RESULTS

The incidence of SSIs in the non-AP after 48 h postoperatively group (98/963, 10.2%) was notably lower than that in the AP after 48 h postoperatively group (22/110, 20.0%) (P = 0.002). Other HAIs incidence was not significantly different between the non-AP after 48 h postoperatively group (77/963, 8.0%) and the AP after 48 h postoperatively group (11/110, 10.0%) (P = 0.468). Multiple regression analysis demonstrated that AP after 48 h postoperatively was a risk factor for SSIs (OR = 2.14, 95% CI 1.28-3.59) but not for other HAIs (OR = 1.24, 95% CI 0.63-2.42) after adjustment for age, gender, and diabetes. Subsequent to adjustment for all confounding factors, AP after 48 h postoperatively was not a influence factor for SSIs (OR = 2.13, 95% CI 0.76-5.99) and other HAIs (OR = 3.69, 95% CI 0.99-13.81).

CONCLUSIONS

AP after 48 h postoperatively following pancreatic surgery was not associated with the lower morbidity rate of SSIs and other HAIs. Nonetheless, this study may facilitate further development of strategies towards standardization of the duration of AP management of pancreatic surgery.

Prevalence and risk factors for colonisation and infection with carbapenem-resistant Enterobacterales in intensive care units: A prospective multicentre study

OBJECTIVES

This study aimed to investigate the prevalence and risk factors for carbapenem-resistant Enterobacterales colonisation/infection at admission and acquisition among patients admitted to the intensive care unit.

RESEARCH METHODOLOGY/DESIGN

A prospective and multicentre study.

SETTING

This study was conducted in 24 intensive care units in Anhui, China.

MAIN OUTCOME MEASURES

Demographic and clinical data were collected, and rectal carbapenem-resistant Enterobacterales colonisation was detected by active screening. Multivariate logistic regression models were used to analyse factors associated with colonisation/infection with carbapenem-resistant Enterobacterales at admission and acquisition during the intensive care unit stay.

RESULTS

There were 1133 intensive care unit patients included in this study. In total, 5.9% of patients with carbapenem-resistant Enterobacterales colonisation/infection at admission, and of which 56.7% were colonisations. Besides, 8.5% of patients acquired carbapenem-resistant Enterobacterales colonisation/infection during the intensive care stay, and of which 67.6% were colonisations. At admission, transfer from another hospital, admission to an intensive care unit within one year, colonisation/infection/epidemiological link with carbapenem-resistant Enterobacterales within one year, and exposure to any antibiotics within three months were risk factors for colonisation/infection with carbapenem-resistant Enterobacterales. During the intensive care stay, renal disease, an epidemiological link with carbapenem-resistant Enterobacterales, exposure to carbapenems and beta-lactams/beta-lactamase inhibitors, and intensive care stay of three weeks or longer were associated with acquisition.

CONCLUSION

The prevalence of colonisation/infection with carbapenem-resistant Enterobacterales in intensive care units is of great concern and should be monitored systematically. Particularly for the 8.5% prevalence of carbapenem-resistant Enterobacterales acquisition during the intensive care stay needs enhanced infection prevention and control measures in these setting. Surveillance of colonisation/infection with carbapenem-resistant Enterobacterales at admission and during the patient's stay represents an early identification tool to prevent further transmission of carbapenem-resistant Enterobacterales.

IMPLICATIONS FOR CLINICAL PRACTICE

Carbapenem-resistant Enterobacterales colonization screening at admission and during the patient's stay is an important tool to control carbapenem-resistant Enterobacterales spread in intensive care units.

Octominin: An antimicrobial peptide with antibacterial and anti-inflammatory activity against carbapenem-resistant Escherichia coli both in vitro and in vivo

OBJECTIVES

The emergence of carbapenem-resistant Escherichia coli (CREC) is a global concern as its prevalence restricts treatment options and poses a considerable threat to public health. In this study, in vitro and in vivo activity of the antimicrobial peptide Octominin against CREC was investigated to reveal possible mechanisms of action. Furthermore, its safety and factors influencing its antibacterial effect were assessed. Additionally, the anti-inflammatory effects of Octominin were examined.

METHODS

The antimicrobial activity of Octominin against 11 strains of CREC was determined using the broth microdilution method, growth curve, and time-kill assay. Its possible mechanism of action was unraveled using the propidium iodide and N-phenyl-1-naphthylamine fluorochrome and lipopolysaccharide-binding assays. To understand the safety and stability of Octominin, its cytotoxicity, hemolysis, and antibacterial activity under various conditions (i.e, temperature, ions) were estimated. Additionally, a Galleria mellonella infection model was utilized to evaluate the efficacy of Octominin in vivo, and qRT-PCR was performed to assess its effect on the expression of proinflammatory cytokines.

RESULTS

Octominin displayed a significant antibacterial effect, with MICs of 4-8 µg/mL and MBCs of 8-16 µg/mL. Octominin exerted its antibacterial effect by disrupting bacterial membranes. Cytotoxicity and hemolysis tests demonstrated the potential application of Octominin in vivo. The G. mellonella infection model asserted the in vivo efficacy of Octominin. Furthermore, Octominin inhibited the expression of proinflammatory cytokines. Although the temperature had little effect on its the activity, serum and ions reduced activity.

CONCLUSION

Octominin is a promising alternative agent with remarkable antibacterial and anti-inflammatory effects for treating infections caused by CREC.

"Superbugs" with hypervirulence and carbapenem resistance in Klebsiella pneumoniae: the rise of such emerging nosocomial pathogens in China

Although hypervirulent Klebsiella pneumoniae (hvKP) can produce community-acquired infections that are fatal in young and adult hosts, such as pyogenic liver abscess, endophthalmitis, and meningitis, it has historically been susceptible to antibiotics. Carbapenem-resistant K. pneumoniae (CRKP) is usually associated with urinary tract infections acquired in hospitals, pneumonia, septicemias, and soft tissue infections. Outbreaks and quick spread of CRKP in hospitals have become a major challenge in public health due to the lack of effective antibacterial treatments. In the early stages of K. pneumoniae development, HvKP and CRKP first appear as distinct routes. However, the lines dividing the two pathotypes are vanishing currently, and the advent of carbapenem-resistant hypervirulent K. pneumoniae (CR-hvKP) is devastating as it is simultaneously multidrug-resistant, hypervirulent, and highly transmissible. Most CR-hvKP cases have been reported in Asian clinical settings, particularly in China. Typically, CR-hvKP develops when hvKP or CRKP acquires plasmids that carry either the carbapenem-resistance gene or the virulence gene. Alternatively, classic K. pneumoniae (cKP) may acquire a hybrid plasmid carrying both genes. In this review, we provide an overview of the key antimicrobial resistance mechanisms, virulence factors, clinical presentations, and outcomes associated with CR-hvKP infection. Additionally, we discuss the possible evolutionary processes and prevalence of CR-hvKP in China. Given the wide occurrence of CR-hvKP, continued surveillance and control measures of such organisms should be assigned a higher priority.

Pediatric intensive care unit treatment alters the diversity and composition of the gut microbiota and antimicrobial resistance gene expression in critically ill children

Introduction

Common critical illnesses are a growing economic burden on healthcare worldwide. However, therapies targeting the gut microbiota for critical illnesses have not been developed on a large scale. This study aimed to investigate the changes in the characteristics of the gut microbiota in critically ill children after short-term pediatric intensive care unit (PICU) treatments.

Methods

Anal swab samples were prospectively collected from March 2021 to March 2022 from children admitted to the PICU of Xinhua Hospital who received broad-spectrum antibiotics on days 1 (the D1 group) and 7 (the D7 group) of the PICU treatment. The structural and functional characteristics of the gut microbiota of critically ill children were explored using metagenomic next-generation sequencing (mNGS) technology, and a comparative analysis of samples from D1 and D7 was conducted.

Results

After 7 days of PICU admission, a significant decrease was noted in the richness of the gut microbiota in critically ill children, while the bacterial diversity and the community structure between groups remained stable to some extent. The relative abundance of Bacilli and Lactobacillales was significantly higher, and that of Campylobacter hominis was significantly lower in the D7 group than in the D1 group. The random forest model revealed that Prevotella coporis and Enterobacter cloacae were bacterial biomarkers between groups. LEfSe revealed that two Gene Ontology entries, GO:0071555 (cell wall organization) and GO:005508 (transmembrane transport), changed significantly after the short-term treatment in the PICU. In addition, 30 KEGG pathways were mainly related to the activity of enzymes and proteins during the processes of metabolism, DNA catabolism and repair, and substance transport. Finally, 31 antimicrobial resistance genes had significantly different levels between the D7 and D1 groups. The top 10 up-regulated genes were Erm(A), ErmX, LptD, eptB, SAT-4, tetO, adeJ, adeF, APH(3')-IIIa, and tetM.

Conclusion

The composition, gene function, and resistance genes of gut microbiota of critically ill children can change significantly after short PICU treatments. Our findings provide a substantial basis for a better understanding of the structure and function of gut microbiota and their role in critical illnesses.

Eravacycline -Synergistic activity with other antimicrobials in carbapenem resistant isolates of Escherichia coli and Acinetobacter baumannii

Carbapenem resistant Enterobacteriaceae are unaffected by most used antibiotics. Carbapenem resistance in Gram-negative bacterial isolates poses a concern. Eravacycline is a potent new therapy option to treat organisms that exhibit extended-spectrum -lactamases and carbapenem-resistant Enterobacteriaceae. The chequerboard microdilution panel method was used to evaluate the effectiveness of eravacycline when combined with other antibiotics. Most effective against Escherichia coli isolates was the combination of eravacycline and polymyxin B, with 60% synergism and eravacycline-Ceftazidime combination was the most potent combination against Acinetobacter baumannii with 80% synergism. Eravacycline is having synergistic benefits against carbapenem-resistant isolates when combined with cephalosporins or polymyxin B.

Integration of phenotypic, qPCR and genome sequencing methodologies for the detection of antimicrobial resistance and virulence in clinical isolates of a tertiary hospital, India

The emergence of antimicrobial resistance (AMR) and virulence in clinical isolates is a significant public health concern. The rapid and accurate detection of these traits in clinical isolates is essential for effective infection control and treatment. We demonstrated the integration of multiple detection methodologies, including phenotypic testing, quantitative polymerase chain reaction (qPCR), and genome sequencing, to detect AMR and virulence in clinical isolates. One hundred sixty-two gram-negative bacterial clinical isolates were selected for this study from the Shri Vinoba Bhave Civil Hospital, Silvassa, a tertiary government hospital. Antimicrobial susceptibility was detected by determining the Minimum Inhibitory Concentration (MIC) using Vitek-2, whereas the combined disk (CD) method was used for phenotypic detection of carbapenemase activity. The highest sensitivity rates were obtained for antibiotics colistin 87.93%, amikacin 67.52%, tigecycline 63.39%, nitrofurantoin 60.87%, and gentamycin 56.08%. The most resistant antibiotics were ceftazidime (71.93%), ciprofloxacin (67.95%) and trimethoprim/sulfamethoxazole (65.56%). Approximately 46.91% (76) of all the isolates were MBL isolates. The qPCR results confirmed the presence of blaNDM-1 in 29.01% of the isolates. The blaNDM-1 harbouring isolates in descending order, were Acinetobacter, Enterobacter cloacae, and Klebsiella pneumoniae. Klebsiella and Acinetobacter isolates were extensively drug-resistant. Whole genome sequencing performed on one of the Klebsiella pneumoniae isolates revealed the presence of many virulence factors, which increased the pathogenicity of the clinical isolates. The results showed that antimicrobial resistance, including carbapenem resistance, blaNDM-1, and virulence factors, was highly prevalent among isolates from tertiary clinical hospitals. The integration of multiple detection methodologies can potentially improve the detection of AMR and virulence in clinical isolates, leading to better patient outcomes and a reduced spread of these essential traits.

Establishment and Validation of Models for the Risk of Multi-Drug Resistant Bacteria Infection and Prognosis in Elderly Patients with Pulmonary Infection: A Multicenter Retrospective Study

Purpose

The aim of this study was to establish risk prediction and prognosis models for multidrug-resistant bacterial infections (MDRB) in elderly patients with pulmonary infections in a multicenter setting.

Patients and Methods

This study is a retrospective cohort analysis in Anhui province of China. Data dimension reduction and feature selection were performed using the lasso regression model. Multifactorial regression analysis to identify risk factors associated with MDRB infection and prognosis. The relevant risks of each patient in the prognostic training cohort were scored based on prognostic independent risk factors. Subsequently, patients were classified into high-risk and low-risk groups, and survival differences were compared between them. Finally, models were established based on independent risk factors for infection, risk groups, and independent prognostic factors, and were presented on nomograms. The predictive accuracy of the model was assessed using corresponding external validation set data.

Results

The study cohort comprised 994 elderly patients with pulmonary infection. Multivariate analysis revealed that endotracheal intubation, previous antibiotic use beyond 2 weeks, and concurrent respiratory failure or cerebrovascular disease were independent risk factors associated with the incidence of MDRB infection. Cox regression analysis identified respiratory failure, malnutrition, an APACHE II score of at least 20, and higher blood creatinine levels as independent prognostic risk factors. The models were validated using an external validation dataset from multiple centers, which demonstrated good diagnostic ability and a good fit with a fair benefit.

Conclusion

In conclusion, our study provides an appropriate and generalisable assessment of risk factors affecting infection and prognosis in patients with MDRB, contributing to improved early identification of patients at higher risk of infection and death, and appropriately guiding clinical management.

Comparing the transmission of carbapenemase-producing and extended-spectrum beta-lactamase-producing Escherichia coli between broiler chickens

The emergence of carbapenemase-producing Enterobacteriaceae (CPE) is a threat to public health, because of their resistance to clinically important carbapenem antibiotics. The emergence of CPE in meat-producing animals is particularly worrying because consumption of meat contaminated with resistant bacteria comparable to CPE, such as extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae, contributed to colonization in humans worldwide. Currently, no data on the transmission of CPE in livestock is available. We performed a transmission experiment to quantify the transmission of CPE between broilers to fill this knowledge gap and to compare the transmission rates of CPE and other antibiotic-resistant E. coli. A total of 180 Ross 308 broiler chickens were distributed over 12 pens on the day of hatch (day 0). On day 5, half of the 10 remaining chickens in each pen were orally inoculated with 5·102 colony-forming units of CPE, ESBL, or chloramphenicol-resistant E. coli (catA1). To evaluate the effect of antibiotic treatment, amoxicillin was given twice daily in drinking water in 6 of the 12 pens from days 2-6. Cloacal swabs of all animals were taken to determine the number of infectious broilers. We used a Bayesian hierarchical model to quantify the transmission of the E. coli strains. E. coli can survive in the environment and serve as a reservoir. Therefore, the susceptible-infectious transmission model was adapted to account for the transmission of resistant bacteria from the environment. In addition, the caecal microbiome was analyzed on day 5 and at the end of the experiment on day 14 to assess the relationship between the caecal microbiome and the transmission rates. The transmission rates of CPE were 52 - 68 per cent lower compared to ESBL and catA1, but it is not clear if these differences were caused by differences between the resistance genes or by other differences between the E. coli strains. Differences between the groups in transmission rates and microbiome diversity did not correspond to each other, indicating that differences in transmission rates were probably not caused by major differences in the community structure in the caecal microbiome. Amoxicillin treatment from day 2-6 increased the transmission rate more than three-fold in all inoculums. It also increased alpha-diversity compared to untreated animals on day 5, but not on day 14, suggesting only a temporary effect. Future research could incorporate more complex transmission models with different species of resistant bacteria into the Bayesian hierarchical model.

Increased antibiofilm and growth inhibitory effect of Imipenem/Cilastatin nanoliposomes against clinical Pseudomonas aeruginosa isolates

Numerous infections are linked to Pseudomonas aeruginosa. It is one of the major medical concerns because of virulence and antibiotic resistance. Antibiotic encapsulation in liposomes is a good strategy for controlling infections caused by this microorganism. Evaluation of anti-Pseudomonas aeruginosa effect of liposomal form of Imipenem/Cilastatin in vitro condition. By using the disk agar diffusion technique, the isolates' pattern of antibiotic resistance was identified. The antibiotic was placed into the nanoliposome after it had been made using the thin layer and ethanol injection techniques. SEM and DLS were used to determine the size, shape, and zeta potential of the encapsulated drug form and the empty nanoliposome. Additionally, Imipenem/Cilastatin encapsulation in nanoliposomes was studied using FT-IR spectroscopy. In the microbial assay experiments the MIC, MBC and MBEC of liposomal and free drug forms were determined. The nanoparticles were spherical, with a diameter ranging from 30 to 39 nm, and the EE% in the thin layer and ethanol injection procedures were 97 and 98, respectively. Imipenem/Cilastatin nanoliposomes showed peaks at 3009 cm-1 and 1650 cm-1, demonstrating the thermodynamic stability for the chemical structure of the drug enclosed and validating the encapsulation of antibiotic in the nanoliposomes. When compared to free drug forms, nanoliposomes had lower MIC and MBC values in the majority of the isolates and had a greater ability to eradicate the biofilm formation. It was shown that the two nanoliposome preparation techniques were more efficient in 80% of the isolates, which had outcomes that were consistent with those of numerous other investigations. Overall, we demonstrated that the antibacterial activity of nanoliposomes was higher than that of the free drug form based on the evaluation of their MIC and MBC. Pharmaceutical nanoliposome techniques provide an excellent future perspective on how to manage microbial infections that are resistant to antibiotics.

Antibiotic-Resistant ESKAPE Pathogens and COVID-19: The Pandemic beyond the Pandemic

Antibacterial resistance is a renewed public health plague in modern times, and the COVID-19 pandemic has rekindled this problem. Changes in antibiotic prescribing behavior, misinformation, financial hardship, environmental impact, and governance gaps have generally enhanced the misuse and improper access to antibiotics during the COVID-19 pandemic. These determinants, intersected with antibacterial resistance in the current pandemic, may amplify the potential for a future antibacterial resistance pandemic. The occurrence of infections with multidrug-resistant (MDR), extensively drug-resistant (XDR), difficult-to-treat drug-resistant (DTR), carbapenem-resistant (CR), and pan-drug-resistant (PDR) bacteria is still increasing. The aim of this review is to highlight the state of the art of antibacterial resistance worldwide, focusing on the most important pathogens, namely Enterobacterales, Acinetobacter baumannii, and Klebsiella pneumoniae, and their resistance to the most common antibiotics.

Multiplex lateral flow test strip for detection of carbapenemase genes using barcoded tetrahedral DNA capture probe-based biosensing interface

Carbapenem-resistant Enterobacterales pose significant global health challenges due to their rapid spread and ability to hydrolyse various beta-lactam antibiotics. Rapid tests for these carbapenemase genes are crucial to ensure appropriate prescription administration and infection control. In this study, we developed a rapid visual nanodiagnostic platform for multiplexed detection of carbapenemase genes using a lateral flow strip. The nanodiagnostic strip was designed with separate barcoded DNA tetrahedrons for the blaKPC and blaNDM genes. These tetrahedrons were distributed on a nitrocellulose membrane at two different test lines as capture probes. When tested against a panel of carbapenemase genes, the tetrahedral probes captured single-stranded amplicons of asymmetric PCR via strand hybridisation. The amplicons acted as bridging elements, binding the DNA-modified gold nanoparticles to the test line of the strip, resulting in clear visual readouts specific to the blaKPC and blaNDM genes. By employing barcoded tetrahedrons and asymmetric PCR in conjunction with the lateral flow strip, a single diagnostic test enabled the detection of multiple carbapenemase genes. The test yielded results as low as 0.12 fM for blaKPC and 0.05 fM for blaNDM within 75 min. Furthermore, the strip effectively identified specific carbapenemase genes in clinical isolates using real-time PCR, antibody-based lateral flow systems for carbapenemase detection, and carbapenemase phenotype experiments. Thus, the strip develop has a high potential for testing blaKPC and blaNDM genes in practice.

Persistent transmission of carbapenem-resistant, hypervirulent Klebsiella pneumoniae between a hospital and urban aquatic environments

The increasing prevalence of infections caused by carbapenem-resistant hypervirulent Klebsiella pneumoniae strains (CR-hvKP) prompts the question of whether these strains also circulate outside of clinical settings. However, the environmental occurrence and dissemination of CR-hvKP are poorly studied. In the current study, we investigated the epidemiological characteristics, and dissemination dynamics of carbapenem-resistant K. pneumoniae (CRKP) isolated from a hospital, an urban wastewater treatment plant (WWTP), and adjacent rivers in Eastern China during one year of monitoring. A total of 101 CRKP were isolated, 54 were determined to be CR-hvKP harboring pLVPK-like virulence plasmids, which were isolated from the hospital (29 out of 51), WWTP (23 out of 46), and rivers (2 out of 4), respectively. The period with lowest detection rate of CR-hvKP in the WWTP, August, corresponded with the lowest detection rate at the hospital. Comparing the inlet and outlet of the WWTP, no significant reduction of the detection of CR-hvKP and relative abundance of carbapenem resistance genes was observed. The detection rate of CR-hvKP and the relative abundance of carbapenemase genes were significantly higher in the WWTP in colder months compared to warmer months. Clonal dissemination of CR-hvKP clones of ST11-KL64 between the hospital and the aquatic environment, as well as the horizontal spread of IncFII-IncR and IncC plasmids carrying carbapenemase genes, was observed. Furthermore, phylogenetic analysis showed that the ST11-KL64 CR-hvKP strain has spread nationally by interregional transmission. These results indicated transmission of CR-hvKP clones between hospital and urban aquatic environments, prompting the need for improved wastewater disinfection and epidemiological models to predict the public health hazard from prevalence data of CR-hvKP.

A review of Spaulding's classification system for effective cleaning, disinfection and sterilization of reusable medical devices: Viewed through a modern-day lens that will inform and enable future sustainability

Despite advances in medicine and innovations in many underpinning fields including disease prevention and control, the Spaulding classification system, originally proposed in 1957, remains widely used for defining the disinfection and sterilization of contaminated re-usable medical devices and surgical instruments. Screening PubMed and Scopus databases using a PRISMA guiding framework generated 272 relevant publications that were used in this review. Findings revealed that there is a need to evolve how medical devices are designed, and processed by cleaning, disinfection (and/or sterilization) to mitigate patient risks, including acquiring an infection. This Spaulding Classification remains in use as it is logical, easily applied and understood by users (microbiologists, epidemiologists, manufacturers, industry) and by regulators. However, substantial changes have occurred over the past 65 years that challenge interpretation and application of this system that includes inter alia emergence of new pathogens (viruses, mycobacteria, protozoa, fungi), a greater understanding of innate and adaptive microbial tolerance to disinfection, toxicity risks, increased number of vulnerable patients and associated patient procedures, and greater complexity in design and use of medical devices. Common cited examples include endoscopes that enable non- or minimal invasive procedures but are highly sophisticated with various types of materials (polymers, electronic components etc), long narrow channels, right angle and heat-sensitive components and various accessories (e.g., values) that can be contaminated with high levels of microbial bioburden and patient tissues after use. Contaminated flexible duodenoscopes have been a source of several significant infection outbreaks, where at least 9 reported cases were caused by multidrug resistant organisms [MDROs] with no obvious breach in processing detected. Despite this, there is evidence of the lack of attention to cleaning and maintenance of these devices and associated equipment. Over the last few decades there is increasing genomic evidence of innate and adaptive resistance to chemical disinfectant methods along with adaptive tolerance to environmental stresses. To reduce these risks, it has been proposed to elevate classification of higher-risk flexible endoscopes (such as duodenoscopes) from semi-critical [contact with mucous membrane and intact skin] to critical use [contact with sterile tissue and blood] that entails a transition to using low-temperature sterilization modalities instead of routinely using high-level disinfection; thus, increasing the margin of safety for endoscope processing. This timely review addresses important issues surrounding use of the Spaulding classification system to meet modern-day needs. It specifically addresses the need for automated, robust cleaning and drying methods combined with using real-time monitoring of device processing. There is a need to understand entire end-to-end processing of devices instead of adopting silo approaches that in the future will be informed by artificial intelligence and deep-learning/machine learning. For example, combinational solutions that address the formation of complex biofilms that harbour pathogenic and opportunistic microorganisms on the surfaces of processed devices. Emerging trends are addressed including future sustainability for the medical devices sector that can be enabled via a new Quintuple Helix Hub approach that combines academia, industry, healthcare, regulators, and society to unlock real world solutions.

Evolution of carbapenem resistance in klebsiella pneumoniae and escherichia coli carrying blaNDM-1 gene: imipenem exposure results in sustained resistance memory of strains in vitro

BACKGROUND

Antibiotics exert an outstanding selective pressure on bacteria, forcing their chromosomal gene mutations and drug resistance genes to spread. The objective of this study is to evaluate the expression of the New Delhi Metallo-β-Lactamase-1 gene (bla_NDM-1) in the clinical isolate (Klebsiella pneumoniae TH-P12158), transformant strains Escherichia coli BL21 (DE3)-bla_NDM-1, and Escherichia coli DH5α- bla_NDM-1 when exposed to imipenem.

METHODS

β-Lactamase genes (bla_SHV, bla_TEM-1, bla_CTX-M-9, bla_IMP, bla_NDM-1, bla_KPC, bla_OXA, bla_GES, and bla_DHA) from randomly selected carbapenems-sensitive K.pneumoniae (n = 20) and E.coli (n = 20) strains were amplified by PCR. The recombinant plasmid of pET-28a harboring bla_NDM-1 was transformed into E.coli BL21 (DE3) and E.coli DH5α by electroporation. The resistance phenotype and higher bla_NDM-1 expression in K.pneumoniae TH-P12158, transformant E.coli BL21 (DE3)-bla_NDM-1, and E.coli DH5α-bla_NDM-1 were observed when exposed to imipenem with grade increasing, decreasing, and canceling doses, respectively.

RESULTS

After being exposed to different doses of imipenem, the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) of antimicrobial drugs and bla_NDM-1 expression of strains increased, which was positively correlated with doses of imipenem. On the contrary, with the decrease or cancellation of imipenem doses, the bla_NDM-1 expression was deteriorated, while the MIC and MBC values remained relatively stable. These results demonstrated that low doses of imipenem (˂MIC) could press bla_NDM-1 positive strains producing stable drug resistance memory and altered bla_NDM-1 expression.

CONCLUSIONS

Low doses of imipenem could press bla_NDM-1 positive strains producing sustained resistance memory and altered bla_NDM-1 expression. In particular, the positive correlation between the resistance genes expression and antibiotics exposure shows promising guiding significance for clinical medication.

Transferable IncX3 plasmid harboring blaNDM-1, bleMBL, and aph(3')-VI genes from Klebsiella pneumoniae conferring phenotypic carbapenem resistance in E. coli

BACKGROUND

The dissemination of carbapenem resistance via carbapenemases, such as the metallo-β-lactamase NDM, among Enterobacterales poses a public health threat. The aim of this study was to characterize a plasmid carrying the blaNDM-1 gene, which was extracted from a clinical Klebsiella pneumoniae uropathogen from an Egyptian patient suffering from a urinary tract infection.

METHODS AND RESULTS

The recovered plasmid was transformed into competent E. coli DH5α which acquired phenotypic resistance to cefoxitin, ceftazidime, and ampicillin/sulbactam, and intermediate sensitivity to ceftriaxone and imipenem (a carbapenem). Whole plasmid sequencing was performed on the extracted plasmid using the DNBSEQ™ platform. The obtained forward and reverse reads were assembled into contigs using the PRINSEQ and PLACNETw web tools. The obtained contigs were uploaded to PlasmidFinder and ResFinder for in silico plasmid typing and detection of antimicrobial resistance genes, respectively. The final consensus sequence was obtained using the Staden Package software. The plasmid (pNDMKP37, NCBI accession OK623716.1) was typed as an IncX3 plasmid with a size of 46,160 bp and harbored the antibiotic resistance genes blaNDM-1, bleMBL, and aph(3')-VI. The plasmid also carried mobile genetic elements involved in the dissemination of antimicrobial resistance including insertion sequences IS30, IS630, and IS26.

CONCLUSIONS

This is Egypt's first report of a transmissible plasmid co-harboring blaNDM-1 and aph(3')-VI genes. Moreover, the respective plasmid is of great medical concern as it has caused the horizontal transmission of multidrug-resistant phenotypes to the transformant. Therefore, new guidelines should be implemented for the rational use of broad-spectrum antibiotics, particularly carbapenems.

Epidemiology and mortality outcome of carbapenem- and colistin-resistant Klebsiella pneumoniae, Escherichia coli, Acinetobacter baumannii, and Pseudomonas aeruginosa bloodstream infections

BACKGROUND

Bloodstream infections caused by carbapenem-resistant Gram-negative bacteria represent a major therapeutic challenge to clinicians worldwide. This study examined the epidemiology of carbapenem and colistin resistance in Klebsiella pneumoniae, Escherichia coli, Pseudomonas aeruginosa, and Acinetobacter baumannii blood isolates in an academic institution in Oman.

METHODS

Adult patients with bloodstream infections caused by Klebsiella pneumoniae, Escherichia coli, Pseudomonas aeruginosa, and Acinetobacter baumannii, between January 1, 2017, and December 31, 2020, were identified. Rates of carbapenem resistance, carbapenem-colistin dual resistance, and 30-day all-cause mortality were examined.

RESULTS

585 non-repeat bloodstream infections due to Klebsiella pneumoniae, Escherichia coli, Pseudomonas aeruginosa, and Acinetobacter baumannii were identified during the study period. OXA-48 was the most prevalent carbapenemase gene in carbapenem-resistant K. pneumoniae blood isolates. Carbapenem resistance was observed in 160 (27.7%) of blood isolates, with 131 (81.9%) of these being healthcare-onset cases. Carbapenem resistance was highest in Acinetobacter baumannii (80.4%), followed by Klebsiella pneumoniae (46.4%), and Pseudomonas aeruginosa (29.9%). Sixteen (13.4%) of the carbapenem-resistant blood isolates were found to be colistin resistant. Thirty-day all-cause mortality was 68.1% in patients with bloodstream infections caused by carbapenem-resistant isolates, versus 21.3% in patients with bloodstream infections caused by carbapenem-susceptible isolates.

CONCLUSION

The prevalence of carbapenem resistance and carbapenem-colistin dual resistance in Gram-negative blood culture isolates from patients with bloodstream infections is unacceptably high. Patients with bloodstream infections due to carbapenem-resistant isolates had substantially higher mortality.

Antibiotic susceptibility pattern, risk factors, and prediction of carbapenem-resistant Pseudomonas aeruginosa in patients with nosocomial pneumonia

Objectives

This study was aimed at describing antibiotic susceptibility patterns and developing a predictive model by assessing risk factors for carbapenem-resistant Pseudomonas aeruginosa (CRPA).

Methods

A retrospective case-control study was conducted at a teaching hospital in China from May 2019 to July 2021. Patients were divided into the carbapenem-susceptible P. aeruginosa (CSPA) group and the CRPA group. Medical records were reviewed to find an antibiotic susceptibility pattern. Multivariate analysis results were used to identify risk factors and build a predictive model.

Results

A total of 61 among 292 patients with nosocomial pneumonia were infected with CRPA. In the CSPA and CRPA groups, amikacin was identified as the most effective antibiotic, with susceptibility of 89.7%. The CRPA group showed considerably higher rates of resistance to the tested antibiotics. Based on the results of mCIM and eCIM, 28 (45.9%) of 61 isolates might be carbapenemase producers. Independent risk factors related to CRPA nosocomial pneumonia were craniocerebral injury, pulmonary fungus infection, prior use of carbapenems, prior use of cefoperazone-sulbactam, and time at risk (≥15 d). In the predictive model, a score >1 point indicated the best predictive ability.

Conclusions

CRPA nosocomial pneumonia could be predicted by risk factor assessment particularly based on the underlying disease, antimicrobial exposure, and time at risk, which could help prevent nosocomial pneumonia.

Hospital sanitary facilities on wards with high antibiotic exposure play an important role in maintaining a reservoir of resistant pathogens, even over many years

BACKGROUND

Hospitals with their high antimicrobial selection pressure represent the presumably most important reservoir of multidrug-resistant human pathogens. Antibiotics administered in the course of treatment are excreted and discharged into the wastewater system. Not only in patients, but also in the sewers, antimicrobial substances exert selection pressure on existing bacteria and promote the emergence and dissemination of multidrug-resistant clones. In previous studies, two main clusters were identified in all sections of the hospital wastewater network that was investigated, one K. pneumoniae ST147 cluster encoding NDM- and OXA-48 carbapenemases and one VIM-encoding P. aeruginosa ST823 cluster. In the current study, we investigated if NDM- and OXA-48-encoding K. pneumoniae and VIM-encoding P. aeruginosa isolates recovered between 2014 and 2021 from oncological patients belonged to those same clusters.

METHODS

The 32 isolates were re-cultured, whole-genome sequenced, phenotypically tested for their antimicrobial susceptibility, and analyzed for clonality and resistance genes in silico.

RESULTS

Among these strains, 25 belonged to the two clusters that had been predominant in the wastewater, while two others belonged to a sequence-type less prominently detected in the drains of the patient rooms.

CONCLUSION

Patients constantly exposed to antibiotics can, in interaction with their persistently antibiotic-exposed sanitary facilities, form a niche that might be supportive for the emergence, the development, the dissemination, and the maintenance of certain nosocomial pathogen populations in the hospital, due to antibiotic-induced selection pressure. Technical and infection control solutions might help preventing transmission of microorganisms from the wastewater system to the patient and vice versa, particularly concerning the shower and toilet drainage. However, a major driving force might also be antibiotic induced selection pressure and parallel antimicrobial stewardship efforts could be essential.

In vitro and in silico antibacterial evaluation of coumarin derivatives against MDR strains of Staphylococcus aureus and Escherichia coli

The increase in antibiotic resistance rates has attracted the interest of researchers for antibacterial compounds capable of potentiating the activity of conventional antibiotics. Coumarin derivatives have been reported to develop effective antibacterials with possible new mechanisms of action for treating infectious diseases caused by bacteria with a profile of drug resistance. In this context, the aim of the present study we have now prepared one variety of new synthetic coumarins evaluating the pharmacokinetic and chemical similarity in silico, their antimicrobial activity against Staphylococcus aureus (ATCC 25923) and Escherichia coli (ATCC 25922), and potential for the modulation of antibiotic resistance against Staphylococcus aureus (SA10) and Escherichia coli (EC06) clinical isolate bacteria by in vitro assay. The antibacterial activity and antibiotic-enhancing properties were evaluated by the broth microdilution method and pharmacokinetically characterized according to the Lipinsk rule of 5 and had their similarity analyzed in databases such as ChemBL and CAS SciFinder. The results demonstrated that only compound C13 showed significant antibacterial activity (MIC ≤256 μg/mL), and all other coumarins did not display relevant antibacterial activity (MIC ≥1024 μg/mL). However, they did modulate the antibiotics activities to norfloxacin and gentamicin, except, compound C11 to norfloxacin against Staphylococcus aureus (SA10). The in silico properties prediction and drug-likeness results demonstrated that all coumarins presented a good drug-likeness score with no violations and promising in silico pharmacokinetic profiles showing that they have the potential to be developed into an oral drug. The results indicate that the coumarin derivatives showed good in vitro antibacterial activity. These new coumarin derivatives also demonstrated the capacity to modulate antibiotic resistance with potential synergy action for current antimicrobials assayed, as antibiotic adjuvants, to reduce the emergence of antimicrobial resistance.

Development of a Novel Antibacterial Peptide, PAM-5, via Combination of Phage Display Selection and Computer-Assisted Modification

Antibacterial peptides (ABPs) have been proposed as potential candidates for alternative antibacterial agents due to the extensive dissemination of antibiotic resistance. However, ABP isolation from natural resources can be tedious without consistent yield. Moreover, many natural ABPs are not developed for clinical application due to potential toxicity to mammalian cells. Therefore, the objective of this study was to develop a potent ABP with minimal toxicity via phage display selection followed by computer-assisted modification. Briefly, a 12-mer phage-displayed peptide library was used to isolate peptides that bound to the cell surface of Pseudomonas aeruginosa with high affinity. The affinity-selected peptide with the highest selection frequency was modified to PAM-5 (KWKWRPLKRKLVLRM) with enhanced antibacterial features by using an online peptide database. Using in vitro microbroth dilution assay, PAM-5 was shown to be active against a panel of Gram-negative bacteria and selected Gram-positive bacteria. Interestingly, the peptide was stable in human plasma by exhibiting a similar bactericidal effect via ex vivo assay. Scanning electron microscopy and SYTOX Green uptake assay revealed that PAM-5 was able to cause membrane disruption and permeabilization of the bacteria. Additionally, the peptide was also able to bind to bacterial DNA as demonstrated by gel retardation assay. In the time-kill assay, PAM-5 was shown to kill the bacteria rapidly in 10 min. More importantly, PAM-5 was non-cytotoxic to Vero cells and non-haemolytic to human erythrocytes at all concentrations tested for the antibacterial assays. Thus, this study showed that the combination of phage display screening and computer-assisted modification could be used to develop potent novel ABPs, and PAM-5 derived from these approaches is worth to be further elucidated for its potential clinical use.

Genome-based characterization of conjugative IncHI1B plasmid carrying carbapenemase genes blaVIM-1, blaIMP-23, and truncated blaOXA-256in Klebsiella pneumoniae NTU107224

The wide dissemination of plasmids carrying antibiotic resistance determinants among bacteria is a severe threat to global public health. Here, we characterized an extensively drug-resistant (XDR) Klebsiella pneumoniae NTU107224 by whole genome sequencing (WGS) in combination with phenotypic tests. Broth dilution method was used to determine the minimal inhibitory concentrations (MICs) of NTU107224 to 24 antibiotics. The whole genome sequence of NTU107224 was determined by Nanopore/Illumina hybrid genome sequencing. Conjugation assay was performed to determine the transferability of plasmids in NTU107224 to recipient K. pneumoniae 1706. Larvae infection model was used to determine the effect(s) of conjugative plasmid pNTU107224-1 on bacterial virulence. Among the 24 antibiotics tested, XDR K. pneumoniae NTU107224 had low MICs only for amikacin (≤1 μg/mL), polymyxin B (0.25 μg/mL), colistin (0.25 μg/mL), eravacycline (0.25 μg/mL), cefepime/zidebactam (1 μg/mL), omadacycline (4 μg/mL), and tigecycline (0.5 μg/mL). Whole genome sequencing showed that the closed NTU107224 genome comprises a 5,076,795-bp chromosome, a 301,404-bp plasmid named pNTU107224-1, and a 78,479-bp plasmid named pNTU107224-2. IncHI1B plasmid pNTU107224-1 contained three class 1 integrons accumulated various antimicrobial resistance genes (including carbapenemase genes bla_VIM-1, bla_IMP-23, and truncated bla_OXA-256) and the blast results suggested the dissemination of IncHI1B plasmids in China. By day 7 after infection, larvae infected with K. pneumoniae 1706 and transconjugant had 70% and 15% survival rates, respectively. We found that the conjugative plasmid pNTU107224-1 is closely related to IncHI1B plasmids disseminated in China and contributes to the virulence and antibiotic resistance of pathogens.

Ceftazidime-Avibactam (C/A) Resistant, Meropenem Sensitive KPC-Producing Klebsiella pneumoniae in ICU Setting: We Are What We Are Treated with?

The continuous spread of carbapenem-resistant Klebsiella pneumoniae (CP-Kp) strains presents a severe challenge to the healthcare system due to limited therapeutic options and high mortality. Since its availability, ceftazidime/avibactam (C/A) has become a first-line option against KPC-Kp, but C/A-resistant strains have been reported increasingly, especially with pneumonia or prior suboptimal blood exposure to C/A treatment. A retrospective, observational study was conducted with all patients admitted to the Intensive Care Unit (ICU) dedicated to COVID-19 patients at the City of Health & Sciences in Turin, between 1 May 2021 and 31 January 2022, with the primary endpoint to study strains with resistance to C/A, and secondly to describe the characteristics of this population, with or without previous exposure to C/A. Seventeen patients with colonization or invasive infection due to Klebsiella pneumoniae, C/A resistance, and susceptibility to meropenem (MIC = 2 µg/L) were included; the bla_KPC genotype was detected in all isolates revealing D179Y mutation in the bla_KPC-2 (bla_KPC-33) gene. Cluster analysis showed that 16 out of the 17 C/A-resistant KPC-Kp isolates belonged to a single clone. Thirteen strains (76.5%) were isolated in a 60-day period. Only some patients had a previous infection with non-mutant KPC at other sites (5; 29.4%). Eight patients (47.1%) underwent previous large-spectrum antibiotic treatment, and four patients (23.5%) had prior treatment with C/A. The secondary spread of the D179Y mutation in the bla_KPC-2 during the COVID-19 pandemic needs to be addressed constantly by an interdisciplinary interaction between microbiologists, infection control personnel, clinicians, and infectious diseases consultants to properly diagnose and treat patients.

S, Devi R, Baveja S, Devi S, S. J, Bhattacharya S, S. M. R, Yesudhason B, Shetty V, Mutreja A, Manesh A, Varghese GM, Marwick CA, Parcell BJ, Gilbert IH, Veeraraghavan B. In Vitro Activity of Two Cefepime-Based Novel Combinations, Cefepime/Taniborbactam and Cefepime/Zidebactam, against Carbapenemase-Expressing Enterobacterales Collected in India

In recent times, discovery efforts for novel antibiotics have mostly targeted carbapenemase-producing Gram-negative organisms. Two different combination approaches are pertinent: β-lactam-β-lactamase inhibitor (BL/BLI) or β-lactam-β-lactam enhancer (BL/BLE). Cefepime combined with a BLI, taniborbactam, or with a BLE, zidebactam, has been shown to be promising. In this study, we determined the in vitro activity of both these agents along with comparators against multicentric carbapenemase-producing Enterobacterales (CPE). Nonduplicate CPE isolates of Escherichia coli (n = 270) and Klebsiella pneumoniae (n = 300), collected from nine different tertiary-care hospitals across India during 2019 to 2021, were included in the study. Carbapenemases in these isolates were detected by PCR. E. coli isolates were also screened for the presence of the 4-amino-acid insert in penicillin binding protein 3 (PBP3). MICs were determined by reference broth microdilution. Higher MICs of cefepime/taniborbactam (>8 mg/L) were linked to NDM, both in K. pneumoniae and in E. coli. In particular, such higher MICs were observed in 88 to 90% of E. coli isolates producing NDM and OXA-48-like or NDM alone. On the other hand, OXA-48-like-producing E. coli or K. pneumoniae isolates were nearly 100% susceptible to cefepime/taniborbactam. Regardless of the carbapenemase types and the pathogens, cefepime/zidebactam showed potent activity (>99% inhibited at ≤8 mg/L). It seems that the 4-amino-acid insert in PBP3 (present universally in the study E. coli isolates) along with NDM adversely impact the activity of cefepime/taniborbactam. Thus, the limitations of the BL/BLI approach in tackling the complex interplay of enzymatic and nonenzymatic resistance mechanisms were better revealed in whole-cell studies where the activity observed was a net effect of β-lactamase inhibition, cellular uptake, and target affinity of the combination. IMPORTANCE The study revealed the differential ability of cefepime/taniborbactam and cefepime/zidebactam in tackling carbapenemase-producing Indian clinical isolates that also harbored additional mechanisms of resistance. NDM-expressing E. coli with 4-amino-acid insert in PBP3 are predominately resistant to cefepime/taniborbactam, while the β-lactam enhancer mechanism-based cefepime/zidebactam showed consistent activity against single- or dual-carbapenemase-producing isolates including E. coli with PBP3 inserts.

Carbapenemase-loaded outer membrane vesicles protect Pseudomonas aeruginosa by degrading imipenem and promoting mutation of antimicrobial resistance gene

AIMS

To investigate the effect of Klebsiella pneumoniae carbapenemase (KPC)-loaded outer membrane vesicles (OMVs) in protecting Pseudomonas aeruginosa against imipenem treatment and its mechanism.

METHODS

The OMVs of carbapenem-resistant Klebsiella pneumonia (CRKP) were isolated and purified from the supernatant of bacterial culture by using ultracentrifugation and Optiprep density gradient ultracentrifugation. The transmission electron microscope, bicinchoninic acid, PCR and carbapenemase colloidal gold assays were applied to characterize the OMVs. Bacterial growth and larvae infection experiments were performed to explore the protective function of KPC-loaded OMVs for P. aeruginosa under imipenem treatment. Ultra-performance liquid chromatography, antimicrobial susceptibility testing, whole-genome sequencing and bioinformatics analysis were used to investigate the mechanism of P. aeruginosa resistance phenotype mediated by OMVs.

RESULTS

CRKP secreted OMVs loaded with KPC, which protect P. aeruginosa from imipenem through hydrolysis of antibiotics in a dose- and time-dependent manner. Furthermore, carbapenem-resistant subpopulations were developed in P. aeruginosa by low concentrations of OMVs that were confirmed to inadequately hydrolyze imipenem. Interestingly, none of the carbapenem-resistant subpopulations obtained the exogenous antibiotic resistance genes, but all of them possessed OprD mutations, which was consistent with the mechanism of P. aeruginosa induced by sub-minimal inhibitory concentrations of imipenem.

CONCLUSIONS

OMVs containing KPC provide a novel route for P. aeruginosa to acquire an antibiotic-resistant phenotype in vivo.

Carbapenem-resistant gram-negative bacterial infection in intensive care unit patients: Antibiotic resistance analysis and predictive model development

In this study, we analyzed the antibiotic resistance of carbapenem-resistant gram-negative bacteria (CR-GNB) in intensive care unit (ICU) patients and developed a predictive model. We retrospectively collected the data of patients with GNB infection admitted to the ICU of the First Affiliated Hospital of Fujian Medical University, who were then divided into a CR and a carbapenem-susceptible (CS) group for CR-GNB infection analysis. Patients admitted between December 1, 2017, and July 31, 2019, were assigned to the experimental cohort (n = 205), and their data were subjected to multivariate logistic regression analysis to identify independent risk factors for constructing the nomogram-based predictive model. Patients admitted between August 1, 2019, and September 1, 2020, were assigned to the validation cohort for validating the predictive model (n = 104). The Hosmer-Lemeshow test and receiver operating characteristic (ROC) curve analysis were used to validate the model's performance. Overall, 309 patients with GNB infection were recruited. Of them, 97 and 212 were infected with CS-GNB and CR-GNB, respectively. Carbapenem-resistant Klebsiella pneumoniae (CRKP), carbapenem-resistant Acinetobacter baumannii (CRAB) and carbapenem-resistant Pseudomonas aeruginosa (CRPA) were the most prevalent CR-GNB. The multivariate logistic regression analysis results of the experimental cohort revealed that a history of combination antibiotic treatments (OR: 3.197, 95% CI: 1.561-6.549), hospital-acquired infection (OR: 3.563, 95% CI: 1.062-11.959) and mechanical ventilation ≥ 7 days (OR: 5.096, 95% CI: 1.865-13.923) were independent risk factors for CR-GNB infection, which were then used for nomogram construction. The model demonstrated a good fit of observed data (p = 0.999), with an area under the ROC curve (AUC) of 0.753 (95% CI: 0.685-0.820) and 0.718 (95% CI: 0.619-0.816) for the experimental and validation cohort, respectively. The decision curve analysis results suggested that the model has a high practical value for clinical practice. The Hosmer-Lemeshow test indicated a good fit of the model in the validation cohort (p-value, 0.278). Overall, our proposed predictive model exhibited a good predictive value in identifying patients at high risk of developing CR-GNB infection in the ICU and could be used to guide preventive and treatment measures.

Multicenter Surveillance of Antimicrobial Resistance among Gram-Negative Bacteria Isolated from Bloodstream Infections in Ghana

BACKGROUND

Antimicrobial resistance (AMR) in Gram-negative bacteria-causing bloodstream infections (BSIs), such as Klebsiella pneumoniae and non-typhoidal Salmonella (NTS), is a major public health concern. Nonetheless, AMR surveillance remains scarce in sub-Saharan Africa, where BSI treatment is largely empirical. The aim of the study was to determine the distribution and AMR patterns of BSI-causing NTS, K. pneumoniae, and other Gram-negative bacteria in Ghana.

METHODS

A cross-sectional study was conducted between April and December 2021 at eleven sentinel health facilities across Ghana as part of a pilot study on the feasibility and implementation of the human sector AMR surveillance harmonized protocol in sub-Saharan Africa. Gram-negative bacteria recovered from blood specimens of febrile patients were identified using MALDI-TOF and evaluated for antimicrobial resistance using the BD Phoenix M50 analyzer and Kirby-Bauer disc diffusion. The Department of Medical Microbiology at the University of Ghana served as the reference laboratory.

RESULTS

Out of 334 Gram-negative blood isolates, there were 18 (5.4%) NTS, 85 (25.5%) K. pneumoniae, 88 (26.4%) Escherichia coli, 40 (12.0%) Acinetobacter baumannii, 25 (7.5%) Pseudomonas aeruginosa, and 77 (23.1%) other Gram-negative bacteria. As a composite, the isolates displayed high resistance to the antibiotics tested-amoxicillin (89.3%), tetracycline (76.1%), trimethoprim-sulfamethoxazole (71.5%), and chloramphenicol (59.7%). Resistance to third-generation cephalosporins [ceftriaxone (73.7%), cefotaxime (77.8%), and ceftazidime (56.3%)] and fluoroquinolones [ciprofloxacin (55.3%)] was also high; 88% of the isolates were multidrug resistant, and the rate of extended-spectrum beta-lactamase (ESBL) production was 44.6%. Antibiotic resistance in K. pneumoniae followed the pattern of all Gram-negative isolates. Antibiotic resistance was lower in NTS blood isolates, ranging between 16.7-38.9% resistance to the tested antibiotics. Resistance rates of 38.9%, 22.2%, and 27.8% were found for cefotaxime, ceftriaxone, and ceftazidime, respectively, and 27.8% and 23.8% for ciprofloxacin and azithromycin, respectively, which are used in the treatment of invasive NTS. The prevalence of multidrug resistance in NTS isolates was 38.9%.

CONCLUSIONS

Multicenter AMR surveillance of Gram-negative blood isolates from febrile patients was well-received in Ghana, and the implementation of a harmonized protocol was feasible. High resistance and multidrug resistance to first- or second-choice antibiotics, including penicillins, third-generation cephalosporins, and fluoroquinolones, were found, implying that these antibiotics might have limited effectiveness in BSI treatment in the country. Continuation of AMR surveillance in Gram-negative blood isolates is essential for a better understanding of the extent of AMR in these pathogens and to guide clinical practice and policymaking.

Molecular and Clinical Characteristics of Carbapenem-Resistant Klebsiella pneumoniae Isolates at a Tertiary Hospital in Wuhan, China

Background

Carbapenem resistant Klebsiella pneumoniae (CRKP) is an independent risk factor for nosocomial infection which poses a serious threat to human health. How to prevent and suppress CRKP infection and explore its drug resistance mechanisms have become a huge challenge and possesses immediate significance.

Methods

A total of 45 CRKP strains isolated from hospitalized patients in Zhongnan Hospital of Wuhan University were collected from August 2018-December 2020. The strain's identification and antimicrobial susceptibility tests were performed using the VITEK 2 automated identification instrument. Single molecule DNA sequencing of 45 CRKP isolates was performed by the third generation high-throughput sequencing technology.

Results

The results were analyzed by multi locus sequence typing (MLST) and phylogenetic analysis. Antimicrobial susceptibility showed that 45 CRKP isolates were multi-drug resistant strains, and the resistance rates to common antibiotics were as high as 68%. Whole genome sequencing results showed that the CRKP strains carried multiple drug resistance genes and virulence factors. MLST analysis found two different sequence types (ST), of which 44 were ST11 and 1 was ST1049.

Conclusion

Through whole genome sequencing (WGS), we found multiple drug-resistant genes and virulence factors, and there was obvious dominant microbiota. The source was mainly related to nosocomial infection. The ST11-KPC Klebsiella pneumoniae was the main type, which was consistent with the most common type in China. We identified several dominant microbiotas which may serve as a target in the clinical prevention and treatment of severe bacterial infections. Our finding may have a role for guiding clinical antibiotic choosing.

Association between antibiotic resistance and increasing ambient temperature in China: An ecological study with nationwide panel data

Background

Antibiotic resistance leads to longer hospital stays, higher medical costs, and increased mortality. However, research into the relationship between climate change and antibiotic resistance remains inconclusive. This study aims to address the gap in the literature by exploring the association of antibiotic resistance with regional ambient temperature and its changes over time.

Methods

Data were obtained from the China Antimicrobial Surveillance Network (CHINET), monitoring the prevalence of carbapenem-resistant Acinetobacter baumannii (CRAB), Klebsiella pneumoniae (CRKP) and Pseudomonas aeruginosa (CRPA) in 28 provinces/regions over the period from 2005 to 2019. Log-linear regression models were established to determine the association between ambient temperature and antibiotic resistance after adjustment for variations in socioeconomic, health service, and environmental factors.

Findings

A 1 °C increase in average ambient temperature was associated with 1.14-fold increase (95%-CI [1.07–1.23]) in CRKP prevalence and 1.06-fold increase (95%-CI [1.03–1.08]) in CRPA prevalence. There was an accumulative effect of year-by-year changes in ambient temperature, with the four-year sum showing the greatest effect on antibiotic resistance. Higher prevalence of antibiotic resistance was also associated with higher antibiotic consumption, lower density of health facilities, higher density of hospital beds and higher level of corruption.

Interpretation

Higher prevalence of antibiotic resistance is associated with increased regional ambient temperature. The development of antibiotic resistance under rising ambient temperature differs across various strains of bacteria.

Funding

The 10.13039/501100012166National Key R&D Program of China (grant number: 2018YFA0606200), 10.13039/501100001809National Natural Science Foundation of China (grant number: 72074234), 10.13039/501100012476Fundamental Scientific Research Funds for Central Universities, P.R. China (grant number: 22qntd4201), 10.13039/100001547China Medical Board (grant number: CMB-OC-19-337).

Cefepime, not Piperacillin/Tazobactam use, for empirical treatment of bloodstream infections caused by Enterobacter spp.: Results from a population pharmacokinetic/pharmacodynamic analysis

OBJECTIVE

There is a paucity of published data to evaluate the efficacy and safety of imipenem, cefepime and piperacillin/tazobactam dosing regimens against bloodstream infections caused by Klebsiella aerogenes (BSIs-Kae) and Enterobacter cloacae complex (BSIs-Ecc) in patients with various degrees of renal function.

METHODS

Pathogens were isolated from China's blood bacterial resistant investigation network. The dosing regimens of imipenem, cefepime and piperacillin were simulated with intermittent infusion and extended infusion. Monte Carlo simulation was performed to calculate the probability of target attainment and a cumulative fraction of response (CFR) against BSIs-Kae/Ecc.

RESULTS

In total, 203 BSIs-Kae, and 785 BSIs-Ecc were isolated from the surveillance network. Imipenem showed the highest in vitro activity against BSIs-Kae/Ecc, followed by cefepime (85%) and piperacillin/tazobactam (70-80%). The MIC₉₀ values of imipenem, cefepime and piperacillin/tazobactam aginst BSIs-Kae and BSIs-Ecc were 1/1 mg/L, 16/16 mg/L, and 64/128 mg/L, respectively. The simulation results showed imipenem achieved the highest CFRs in patients with normal or decreased renal function, with values of 91-99%, followed by FEP (88-96%), without risk of excessive dosing. However, the intermittent and extended dosing regimens of piperacillin/tazobactam were unlikely to provide adequate exposure for empirical management of BSIs-Kae/Ecc (CFRs, 50-80%), regardless of renal function. Besides, the traditional intermittent piperacillin/tazobactam dosing regimens were highly likely to contribute to suboptimal therapeutic exposure when MIC was close to clinical breakpoints.

CONCLUSIONS

Cefepime, not piperacillin/tazobactam, can be a reasonable carbapenem-sparing option in empirically treating BSIs-Kae/Ecc.