Carbapenem-resistant Enterobacteriaceae Research Articles

Epidemiology and antimicrobial susceptibility profiles of Enterobacterales causing bloodstream infections before and during COVID-19 pandemic: Results of the Study for Monitoring Antimicrobial Resistance Trends (SMART) in Taiwan, 2018–2021

BackgroundThe coronavirus disease 2019 (COVID-19) pandemic has contributed to the spread of antimicrobial resistance, including carbapenem-resistant Enterobacterales. MethodsThis study utilized data from the Study for Monitoring Antimicrobial Resistance Trends (SMART) surveillance program in Taiwan. Enterobacterales from patients with bloodstream infections (BSIs) were collected and subjected to antimicrobial susceptibility testing and β-lactamase gene detection using a multiplex PCR assay. Statistical analysis was conducted to compare susceptibility rates and resistance genes between time periods before (2018–2019) and during the COVID-19 pandemic (2020–2021). ResultsA total of 1231 Enterobacterales isolates were collected, predominantly Escherichia coli (55.6%) and Klebsiella pneumoniae (29.2%). The proportion of nosocomial BSIs increased during the COVID-19 pandemic (55.5% vs. 61.7%, p < 0.05). Overall, susceptibility rates for most antimicrobial agents decreased, with Enterobacterales from nosocomial BSIs showing significantly lower susceptibility rates than those from community-acquired BSIs. Among 123 Enterobacterales isolates that underwent molecular resistance mechanism detection, ESBL, AmpC β-lactamase, and carbapenemase genes were detected in 43.1%, 48.8% and 16.3% of the tested isolates, respectively. The prevalence of carbapenemase genes among carbapenem-resistant Enterobacterales increased during the pandemic, although the difference was not statistically significant. Two novel β-lactamase inhibitor combinations, imipenem-relebactam and meropenem-vaborbactam, preserved good efficacy against Enterobacterales. However, imipenem-relebactam showed lower in vitro activity against imipenem-non-susceptible Enterobacterales than that of meropenem-vaborbactam. ConclusionsThe COVID-19 pandemic appears to be associated with a general decrease in antimicrobial susceptibility rates among Enterobacterales causing BSIs in Taiwan. Continuous surveillance is crucial to monitor antimicrobial resistance during the pandemic and in the future.

Fourth national Japanese antimicrobial susceptibility pattern surveillance program: Bacterial isolates from patients with complicated urinary tract infections

IntroductionAntimicrobial susceptibility patterns of bacterial pathogens isolated from patients with complicated urinary tract infections were analyzed using the national surveillance data, comprising 793 bacterial strains from eight clinically relevant species. Materials and methodsData were collected for the fourth national surveillance project from July 2020 to December 2021 by the Japanese Society of Chemotherapy, the Japanese Association for Infectious Disease, and the Japanese Society of Clinical Microbiology. Surveillance was supervised with the cooperation of 43 medical institutions throughout Japan. ResultsFluoroquinolone required a minimum inhibitory concentration (MIC) of 2–64 mg/L to inhibit the 330 tested Escherichia coli strains. The proportion of levofloxacin-resistant E. coli strains increased from 28.6% in 2008 to 29.6% in 2011, 38.5% in 2015, and 44.5% in 2021. The proportion of levofloxacin-resistant strains of Pseudomonas aeruginosa also increased from previous survey results, showing a continuing downward trend. Conversely, the proportion of levofloxacin-resistant strains of Enterococcus faecalis decreased relative to previous reports. Neither multidrug-resistant P. aeruginosa nor carbapenem-resistant Enterobacteriaceae were detected. For methicillin-resistant Staphylococcus aureus (MRSA), the proportion of vancomycin-susceptible strains (MIC of 2 μg/mL) decreased from 14.7% to 7.7%. DiscussionBacterial strains that produced extended-spectrum β-lactamase included E. coli (82/330 strains, 24.8%), Klebsiella pneumoniae (11/68 strains, 16.2%), and Proteus mirabilis (4/26 strains, 15.4%). As compared to previous surveillance reports, these strains showed an increase in proportion over the years.

Molecular epidemiology of carbapenem-resistant gram-negative bacilli in Ecuador

IntroductionCarbapenem-resistant gram-negative bacilli are a worldwide concern because of high morbidity and mortality rates. Additionally, the increasing prevalence of these bacteria is dangerous. To investigate the extent of antimicrobial resistance and prioritize the utility of novel drugs, we evaluated the molecular characteristics and antimicrobial susceptibility profiles of carbapenem-resistant Enterobacterales, Pseudomonas aeruginosa and Acinetobacter baumannii in Ecuador in 2022.MethodsNinety-five clinical isolates of carbapenem non-susceptible gram-negative bacilli were collected from six hospitals in Ecuador. Carbapenem resistance was confirmed with meropenem disk diffusion assays following Clinical Laboratory Standard Institute guidelines. Carbapenemase production was tested using a modified carbapenemase inactivation method. Antimicrobial susceptibility was tested with a disk diffusion assay, the Vitek 2 System, and gradient diffusion strips. Broth microdilution assays were used to assess colistin susceptibility. All the isolates were screened for the blaKPC,blaNDM,blaOXA-48,blaVIM and blaIMP genes. In addition, A. baumannii isolates were screened for the blaOXA-23, blaOXA-58 and blaOXA-24/40 genes.ResultsCarbapenemase production was observed in 96.84% of the isolates. The blaKPC, blaNDM and blaOXA-48 genes were detected in Enterobacterales, with blaKPC being predominant. The blaVIM gene was detected in P. aeruginosa, and blaOXA-24/40 predominated in A. baumannii. Most of the isolates showed co-resistance to aminoglycosides, fluoroquinolones, and trimethoprim/sulfamethoxazole. Both ceftazidime/avibactam and meropenem/vaborbactam were active against carbapenem-resistant gram-negative bacilli that produce serin-carbapenemases.ConclusionThe epidemiology of carbapenem resistance in Ecuador is dominated by carbapenemase-producing K. pneumoniae harbouring blaKPC. Extensively drug resistant (XDR) P. aeruginosa and A. baumannii were identified, and their identification revealed the urgent need to implement strategies to reduce the dissemination of these strains.

469 Diverse Role of blaCTX-M and Porins in Mediating Ertapenem Resistance Among Carbapenem Resistant Enterobacterales

OBJECTIVES/GOALS: In this study, we aim to report the role of porins and blaCTX-M β-lactamases among Escherichia coli and Klebsiella pneumoniae, focusing on emerging carbapenem resistant Enterobacterales (CRE) subtypes, including non-carbapenemase producing Enterobacterales (NCPE) and ertapenem-resistant but meropenem-susceptible (ErMs) strains. METHODS/STUDY POPULATION: Whole genome sequencing was conducted on 76 carbapenem-resistant isolates across 5 hospitals in San Antonio, U.S. Among these, NCP isolates accounted for the majority of CRE (41/76). Identification and antimicrobial susceptibility testing (AST) results were collected from the clinical charts. Repeat speciation was determined through whole genome sequencing (WGS) analysis and repeat AST, performed with microdilution or ETEST®. Minimum inhibitory concentrations (MIC) were consistent with Clinical and Laboratory Standards Institute (CLSI M100, ED33). WGS and qPCR were used to characterize the resistome of all clinical CRE subtypes, while western blotting and liquid chromatography with tandem mass spectrometry (LC-MS-MS) were used to determine porin expression and carbapenem hydrolysis, respectively. RESULTS/ANTICIPATED RESULTS: blaCTX-Mwas found to be most prevalent among NCP isolates (p = 0.02). LC-MS/MS analysis of carbapenem hydrolysis revealed that blaCTX-M-mediated carbapenem hydrolysis, indicating the need to reappraise the term, “non-carbapenemase (NCP)®” for quantitatively uncharacterized CRE strains harboring blaCTX-M. Susceptibility results showed that 56% of all NCPE isolates had an ErMs phenotype (NCPE vs. CPE, p &lt; 0.001), with E. coli driving the phenotype (E. coli vs. K. pneumoniae, p &lt; 0.001). ErMs strains carrying blaCTX-M, had 4-fold more copies of blaCTX-M than ceftriaxone-resistant but ertapenem-susceptible isolates (3.7 v. 0.9, p &lt; 0.001). Immunoblot analysis demonstrated the absence of OmpC expression in NCP-ErMs E. coli, with 92% of strains lacking full contig coverage ofompC. DISCUSSION/SIGNIFICANCE: Overall, this work provides evidence of a collaborative effort between blaCTX-M and OmpC in NCP strains that confer resistance to ertapenem but not meropenem. Clinically, CRE subtypes are not readily appreciated, potentially leading to mismanagement of CRE infected patients. A greater focus on optimal treatments for CRE subtypes is needed.

Dissemination of NDM-1 and OXA-48 Co-producing Carbapenem-resistant Enterobacterales at Two Tertiary Hospitals in Egypt

Dissemination of NDM-1 and OXA-48 Co-producing Carbapenem-resistant Enterobacterales at Two Tertiary Hospitals in Egypt

Prevalence and characterization of Carbapenem-Resistant Enterobacterales among inpatients and outpatients in Skikda, Algeria.

The spread of Carbapenemase-producing Enterobacterales (CPEs) has become a significant concern in Algeria, with limited data available on their presence in community settings. This research investigated the resistance mechanisms of carbapenem-resistant Enterobacterales (CREs) collected from hospitals and the community in Skikda city, Algeria, between December 2020 and June 2022. The study collected Enterobacterales strains resistant to ertapenem from inpatient and outpatient populations. An automated system was used for identification and antibiotic susceptibility testing. β-lactamase production was evaluated through phenotypic tests and confirmed by standard PCR. Lastly, the carbapenemase genes were sequenced using the Sanger method. 17 CRE were isolated, with 9 from inpatients and 8 from outpatients. These isolates belonged to four species: Klebsiella pneumoniae (n = 8), Escherichia coli (n = 6), Enterobacter cloacae (n = 1), and Proteus mirabilis (n = 1). Of 15 CPEs, 11 were extended-spectrum β-lactamases (ESBLs) positive, 5 were plasmid-mediated cephalosporinase (AmpC) positive, and 1 harbored all three β-lactamases. All metallo-β-lactamase-producing strains carried the New Delhi metallo-beta-lactamase gene (blaNDM), including 5 NDM-1 and 7 NDM-5 variants. The presence of blaOXA-48 and blaOXA-244 was observed in one outpatient strain each. NDM was associated with Cefotaximase Munich (CTX-M) ESBL in 8 isolates, while Cephamycinase (CMY) was detected in 3 NDM-5-producing E. coli. This research highlights the rising prevalence of carbapenemases NDM-1 and NDM-5 among inpatients and outpatients and supports the notion that OXA-48 is becoming increasingly widespread beyond Algerian hospitals.

Risk factors for colonization with extended-spectrum cephalosporin-resistant and carbapenem-resistant Enterobacterales among hospitalized patients in Guatemala: An Antibiotic Resistance in Communities and Hospitals (ARCH) study

ObjectivesThe spread of extended-spectrum cephalosporin-resistant Enterobacterales (ESCrE) and carbapenem-resistant Enterobacterales (CRE) has resulted in increased morbidity, mortality, and health care costs worldwide. To identify the factors associated with ESCrE and CRE colonization within hospitals, we enrolled hospitalized patients at a regional hospital located in Guatemala. MethodsStool samples were collected from randomly selected patients using a cross-sectional study design (March-September, 2021), and samples were tested for the presence of ESCrE and CRE. Hospital-based and household variables were examined for associations with ESCrE and CRE colonization using lasso regression models, clustered by ward (n = 21). ResultsA total of 641 patients were enrolled, of whom complete data sets were available for 593. Colonization with ESCrE (72.3%, n = 429/593) was negatively associated with carbapenem administration (odds ratio [OR] 0.21, 95% confidence interval [CI] 0.11-0.42) and positively associated with ceftriaxone administration (OR 1.61, 95% CI 1.02-2.53), as was reported hospital admission within 30 days of the current hospitalization (OR 2.84, 95% CI 1.19-6.80). Colonization with CRE (34.6%, n = 205 of 593) was associated with carbapenem administration (OR 2.62, 95% CI 1.39-4.97), reported previous hospital admission within 30 days of current hospitalization (OR 2.58, 95% CI 1.17-5.72), hospitalization in wards with more patients (OR 1.05, 95% CI 1.02-1.08), hospitalization for ≥4 days (OR 3.07, 95% CI 1.72-5.46), and intubation (OR 2.51, 95% CI 1.13-5.59). No household-based variables were associated with ESCrE or CRE colonization in hospitalized patients. ConclusionThe hospital-based risk factors identified in this study are similar to what has been reported for risk of health care–associated infections, consistent with colonization being driven by hospital settings rather than community factors. This also suggests that colonization with ESCrE and CRE could be a useful metric to evaluate the efficacy of infection and prevention control programs in clinics and hospitals.

Carriage of antimicrobial-resistant Enterobacterales among pregnant women and newborns in Amhara, Ethiopia

ObjectivesInfections are one of the most common causes of neonatal mortality, and maternal colonization has been associated with neonatal infection. In this study, we sought to quantify carriage prevalence of extended-spectrum-beta-lactamase (ESBL) -producing and carbapenem-resistant Enterobacterales (CRE) among pregnant women and their neonates and to characterize risk factors for carriage in rural Amhara, Ethiopia. MethodsWe conducted a prospective cohort study nested in the Birhan field site. We collected rectal and vaginal samples from 211 pregnant women in their third trimester and/or during labor/delivery and perirectal or stool samples from 159 of their neonates in the first week of life. ResultsWe found that carriage of ESBL-producing organisms was fairly common (women: 22.3%, 95% CI: 16.8-28.5; neonates: 24.5%, 95% CI: 18.1-32.0), while carriage of CRE (women: 0.9%, 95% CI: 0.1-3.4; neonates: 2.5%, 95% CI: 0.7-6.3) was rare. Neonates whose mothers tested positive for ESBL-producing organisms were nearly twice as likely to also test positive for ESBL-producing organisms (38.7% vs 21.1%, P-value = 0.06). Carriage of ESBL-producing organisms was also associated with Woreda (district) of sample collection and recent antibiotic use. ConclusionUnderstanding carriage patterns of potential pathogens and antibiotic susceptibility among pregnant women and newborns will inform local, data-driven recommendations to prevent and treat neonatal infections.

High Prevalence of Carbapenem-Resistant Enterobacterales Producing OXA-48 among Carbapenem-Resistant Isolates in a Regional Hospital in Central Taiwan.

In response to the increasing number of carbapenem-resistant Enterobacterales (CRE), we investigated carbapenemase-producing Klebsiella pneumoniae and non-K. pneumoniae epidemiology and genetics. We collected 76 clinical Enterobacterales and 4 stool surveillance Escherichia coli isolates resistant to ertapenem or imipenem. Using polymerase chain reaction (PCR) and DNA sequencing, we assessed carbapenemases, extended-spectrum β-lactamases, and AmpC β-lactamases. Molecular typing via pulsed-field gel electrophoresis (PFGE) and conjugation experiments were conducted to examine resistance gene transfer. Among the 80 isolates, 96.2% harbored at least one carbapenemase gene, with blaOXA-48 in 87.5%. KPC-2 and IMP-8 carbapenemases were found in 15.0 and 22.5% of the isolates, respectively, with 27.5% having 2 or more carbapenemase genes. The PFGE analysis revealed the presence of diverse genotypes. PCR-based plasmid replicon typing identified IncA/C as the most prevalent type among K. pneumoniae isolates (26/29), and IncF and IncFIB among E. coli isolates (22/28). Conjugal transfer was successful for plasmids encoding OXA-48, CTX-M-3, CTX-M-14, CMY-2, and other β-lactamases, except the KPC-2 gene. In conclusion, our study highlights high carbapenemase prevalence in CRE, primarily OXA-48. Multiple carbapenemases within strains were common, and PFGE showed diverse patterns in these carbapenem-resistant isolates.

Comparison of Daily Versus Admission and Discharge Surveillance Cultures for Multidrug-Resistant Organism Detection in an Intensive Care Unit.

Admission and discharge screening of patients for asymptomatic gut colonization with multidrug-resistant organisms (MDROs) is a common approach to active surveillance, but its sensitivity for detecting colonization is uncertain. Daily rectal or fecal swab samples and associated clinical data were collected over 12 months from patients in one 25-bed medical intensive care unit (ICU) in Chicago, IL and tested for the following MDROs: vancomycin-resistant enterococci; third-generation cephalosporin-resistant Enterobacterales, including extended-spectrum β-lactamase-producing Enterobacterales; and carbapenem-resistant Enterobacterales. MDRO detection by (1) admission and discharge surveillance cultures or (2) clinical cultures were compared to daily surveillance cultures. Samples underwent 16S rRNA gene sequencing to measure the relative abundance of operational taxonomic units (OTUs) corresponding to each MDRO. Compared with daily surveillance cultures, admission/discharge cultures detected 91% of prevalent MDRO colonization and 63% of MDRO acquisitions among medical ICU patients. Few (7%) MDRO carriers were identified by clinical cultures alone. Higher relative abundance of MDRO-associated OTUs and specific antibiotic exposures were independently associated with higher probability of MDRO detection by culture. Admission and discharge surveillance cultures underestimated MDRO acquisitions in an ICU. These limitations should be considered when designing sampling strategies for epidemiologic studies that use culture-based surveillance.

High rates of intestinal colonization with carbapenemase producing Enterobacteriaceae inhematopoietic stem cell transplant recipients.

Carbapenem resistant Enterobacteriaceae (CRE) are major human pathogens because, these cause high number of difficult-to-treat infections. Allogeneic hematopoietic stem cell transplant (AHSCT) recipients are highly exposed to these type of bacteria. The aim of our study was to investigate prevalence of CRE colonization in AHSCT patients and to determine genes encoding carbapenem resistance. Aretrospective study conducted between January 2015 and December 2019, involved 55 patients colonized with CRE strains. We determined the rate of antibiotic resistance according to European Committee on Antimicrobial Susceptibility Testing (EUCAST) and the carbapenem resistance genes by PCR assays for genes encoding most frequent β-lactamases namely, blaGES, blaKPC, blaIMI, blaNDM, blaVIM, blaIMP and blaOXA-48. Eighty-one episodes of CRE colonization were recorded in 55 patients, mainly suffering from acute leukaemia (30%) and aplastic anemia (26%). History of hospitalization was noted in 80 episodes. Prior antibiotic treatment, severe neutropenia and corticosteroid therapy were respectively found in 94%, 76% and 58% of cases. Among the 55 patients, six patients (11%) developed a CRE infection. The CRE responsible for colonization were carbapenemase producers in 90% of cases. They belonged mostly to Klebsiella pneumoniae (61/81) and Escherichia coli species (10/81). Antibiotic resistance rates were 100% for ertapenem, 53% for imipenem, 42% for amikacin, 88% for ciprofloxacin and 27% for fosfomycin. Molecular study showed that blaOXA-48 gene was the most frequent (60.5%), followed by blaNDM (58%). Thirty-five (43%) strains were co-producers of carbapenemases. In our study, we report a high rate of CRE intestinal colonization in AHSCT recipients of our center.

Molecular characteristics of carbapenem-resistant Enterobacteriaceae isolated from two tertiary hospitals in the Philippines

Species belonging to the family Enterobacteriaceae cause infections that result in clinically significant morbidity and mortality. These organisms have been shown to harbor multiple mechanisms of resistance to antibiotics, including carbapenems. Molecular characterization of resistance to carbapenems is critical since few effective therapeutic options exist, most of which are difficult to access in resource-limited settings. One hundred twenty-six Enterobacteriaceae isolates with phenotypic resistance to at least one carbapenem were collected from two tertiary hospitals in the Philippines from 2014 to 2016. The organisms were screened for the presence of genes coding for carbapenemases and extended spectrum β-lactamases (ESBLs) using multiplex PCR. Multilocus sequence typing (MLST) was performed for Klebsiella pneumoniae, Escherichia coli and Enterobacter cloacae complex. The majority of the carbapenem-resistant isolates were K. pneumoniae (70/126, 55.5%) followed by K. ozaenae (19/126, 15%). Amplification of genes conferring carbapenem resistance showed blaNDM in 89 isolates (70%), followed by blaKPC in 21 isolates (16%). MLST revealed the presence of different clones including ST16 (5/70), ST17 (3/70) and ST147 (9/70) in K. pneumoniae, and ST10 (3/13) in E. coli. This study shows that blaNDM is the most prevalent carbapenemase type among carbapenem-resistant Enterobacteriaceae (CRE). Presence of carbapenemase gene and multiple ESBLs in the same organism pose a risk in the clinical setting since it could confer higher antibiotic resistance. This high rate of resistance poses the risk of spread since it can be transferred by mobile genetic elements. This study illustrates the acute need for effective therapeutic and hospital infection controls against CREs.

Hospital-acquired and ventilator-associated pneumonia caused by multidrug-resistant Gram-negative pathogens: Understanding epidemiology, resistance patterns, and implications with COVID-19

The ongoing spread of antimicrobial resistance has complicated the treatment of bacterial hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP). Gram-negative pathogens, especially those with multidrug-resistant profiles, including Escherichia coli, Klebsiella pneumoniae, Enterobacter spp., Pseudomonas aeruginosa, and Acinetobacter spp., are important culprits in this type of infections. Understanding the determinants of resistance in pathogens causing pneumonia is ultimately stressing, especially in the shadows of the COVID-19 pandemic, when bacterial lung infections are considered a top priority that has become urgent to revise. Globally, the increasing prevalence of these pathogens in respiratory samples represents a significant infection challenge, with major limitations of treatment options and poor clinical outcomes. This review will focus on the epidemiology of HAP and VAP and will present the roles and the antimicrobial resistance patterns of implicated multidrug-resistant (MDR) Gram-negative pathogens like carbapenem-resistant Acinetobacter baumannii (CRAB), carbapenem-resistant Pseudomonas aeruginosa (CRPA), carbapenem-resistant Enterobacterales (CRE), as well as colistin-resistant Gram-negative pathogens and extended-spectrum β-lactamase (ESBL)-producing Enterobacterales. While emerging from the COVID-19 pandemic, perspectives and conclusions are drawn from findings of HAP and VAP caused by MDR Gram-negative bacteria in patients with COVID-19.

Device-Associated Infections in COVID-19 Patients: Frequency of Resistant Bacteria, Predictors and Mortality in Medellín, Colombia.

Increased antimicrobial use during the COVID-19 pandemic has raised concerns about the spread of resistant bacteria. This study analyzed the frequency of device-associated infections (DAI) caused by resistant bacteria, the predictors of these infections, and 30-day all-cause mortality in patients with and without COVID-19. A retrospective cohort study was conducted on DAI patients admitted to the ICU (intensive care unit) in 20 hospitals in Medellin, Colombia (2020-2021). The exposure assessed was the COVID-19 diagnosis, and outcomes analyzed were resistant bacterial infections and 30-day mortality. Clinical and microbiological information was collected from surveillance databases. Statistical analysis included generalized linear mixed-effects models. Of the 1521 patients included, 1033 (67.9%) were COVID-19-positive and 1665 DAI were presented. Carbapenem-resistant Enterobacteriaceae (CRE) infections predominated during the study (n = 98; 9.9%). The patients with COVID-19 had a higher frequency of metallo-beta-lactamase-producing CRE infections (n = 15; 33.3%) compared to patients without the disease (n = 3; 13.0%). Long-stay in the ICU (RR: 2.09; 95% CI: 1.39-3.16), diabetes (RR: 1.73; 95% CI: 1.21-2.49), and mechanical ventilation (RR: 2.13; 95% CI: 1.01-4.51) were CRE infection predictors in COVID-19 patients, with a mortality rate of 60.3%. CRE infections were predominant in COVID-19 patients. In pandemic situations, the strategies to control DAI should be maintained to avoid infections caused by resistant bacteria, such as length of stay in the ICU and duration of mechanical ventilation.

Antimicrobial and Diagnostic Stewardship of the Novel β-Lactam/β-Lactamase Inhibitors for Infections Due to Carbapenem-Resistant Enterobacterales Species and Pseudomonas aeruginosa.

Carbapenem-resistant Gram-negative bacterial infections are a major public health threat due to the limited therapeutic options available. The introduction of the new β-lactam/β-lactamase inhibitors (BL/BLIs) has, however, altered the treatment options for such pathogens. Thus, four new BL/BLI combinations-namely, ceftazidime/avibactam, meropenem/vaborbactam, imipenem/relebactam, and ceftolozane/tazobactam-have been approved for infections attributed to carbapenem-resistant Enterobacterales species and Pseudomonas aeruginosa. Nevertheless, although these antimicrobials are increasingly being used in place of other drugs such as polymyxins, their optimal clinical use is still challenging. Furthermore, there is evidence that resistance to these agents might be increasing, so urgent measures should be taken to ensure their continued effectiveness. Therefore, clinical laboratories play an important role in the judicious use of these new antimicrobial combinations by detecting and characterizing carbapenem resistance, resolving the presence and type of carbapenemase production, and accurately determining the minimum inhibitor concentrations (MICs) for BL/BLIs. These three targets must be met to ensure optimal BL/BLIs use and prevent unnecessary exposure that could lead to the development of resistance. At the same time, laboratories must ensure that results are interpreted in a timely manner to avoid delays in appropriate treatment that might be detrimental to patient safety. Thus, we herein present an overview of the indications and current applications of the new antimicrobial combinations and explore the diagnostic limitations regarding both carbapenem resistance detection and the interpretation of MIC results. Moreover, we suggest the use of alternative narrower-spectrum antibiotics based on susceptibility testing and present data regarding the effect of synergies between BL/BLIs and other antimicrobials. Finally, in order to address the absence of a standardized approach to using the novel BL/BLIs, we propose a diagnostic and therapeutic algorithm, which can be modified based on local epidemiological criteria. This framework could also be expanded to incorporate other new antimicrobials, such as cefiderocol, or currently unavailable BL/BLIs such as aztreonam/avibactam and cefepime/taniborbactam.

Prevalence and characteristics of ertapenem-mono-resistant isolates among carbapenem-resistant Enterobacterales in China

ABSTRACT Carbapenem-resistant Enterobacterales (CRE), specifically those resistant to only ertapenem among carbapenems (ETP-mono-resistant), are increasingly reported, while the optimal therapy options remain uncertain. To investigate the prevalence and characteristics of ETP-mono-resistant CRE, CRE strains were systematically collected from 102 hospitals across China between 2018 and 2021. A 1:1 randomized matching study was conducted with ETP-mono-resistant strains to meropenem- and/or imipenem-resistant (MEM/IPM-resistant) strains. Antimicrobial susceptibility testing, whole-genome sequencing, carbapenem-hydrolysing activity and the expression of carbapenemase genes were determined. In total, 18.8% of CRE strains were ETP-mono-resistant, with relatively low ertapenem MIC values. ETP-mono-resistant strains exhibited enhanced susceptibility to β-lactams, β-lactam/β-lactamase inhibitor combinations, levofloxacin, fosfomycin, amikacin and polymyxin than MEM/IPM-resistant strains (P < 0.05). Phylogenetic analysis revealed high genetic diversity among ETP-mono-resistant strains. Extended-spectrum β-lactamases (ESBLs) and/or AmpC, as well as porin mutations, were identified as potential major mechanisms mediating ETP-mono-resistance, while the presence of carbapenemases was found to be the key factor distinguishing the carbapenem-resistant phenotypes between the two groups (P < 0.001). Compared with the MEM/IPM-resistant group, limited carbapenemase-producing CRE (CP-CRE) strains in the ETP-mono-resistant group showed a significantly lower prevalence of ESBLs and porin mutations, along with reduced expression of carbapenemase. Remarkably, spot assays combined with modified carbapenem inactivation method indicated that ETP-mono-resistant CP-CRE isolates grew at meropenem concentrations eightfold above their corresponding MIC values, accompanied by rapidly enhanced carbapenem-hydrolysing ability. These findings illustrate that ETP-mono-resistant CRE strains are relatively prevalent and that caution should be exercised when using meropenem alone for treatment. The detection of carbapenemase should be prioritized.

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).

Spread and evolution of blaKPC-plasmid between Serratia marcescens and Klebsiella pneumoniae

ObjectivesblaKPC-carrying Enterobacterales have post great challenges to global healthcare systems. In this study, we reported the evolution and spread of blaKPC between Serratia marcescens and Klebsiella pneumoniae. MethodsFour S. marcescens and one K. pneumoniae strains were isolated from the sputum samples of the patient. Antimicrobial susceptibility tests and whole genome sequencing were performed to investigate the phenotype & genotype of strains. Conjugation assays, cloning experiment and kinetic parameters measuring were performed to explore the spread and antimicrobial resistance mechanisms. ResultsThe evolution and transmission of blaKPC-2 occurred during the treatment of ceftazidime-avibactam and trimethoprim-sulfamethoxazole. Analysis of the antimicrobial susceptibility and genetic profiles of the clinical strains showed that blaKPC-2 evolved into blaKPC-71 and blaKPC-44, together with resistance to ceftazidime-avibactam and carbapenems susceptibility recovery under antimicrobial pressure. Cloning and expression of blaKPC-44 & blaKPC-71 in E. coli DH5α showed that KPC-44 and KPC-71 resulted in a 64∼128-fold increase in the MIC value for ceftazidime-avibactam. Meanwhile, the kinetic assays also showed that the enzyme activity of KPC-44 and KPC-71 towards carbapenems was destroyed and couldn't be inhibited by avibactam. Based on the conjugation assay and whole genome sequence analyses, we provided evolutionary insights into the transmission pathway trace of blaKPC-bearing plasmids between S. marcescens and K. pneumoniae. ConclusionsMixed-species co-infection is one of the risk factors leading to the spread of plasmids carrying carbapenem-resistant genes, and increased surveillance of multidrug-resistant Enterobacterales is urgently needed.

Emergence of pandrug-resistant carbapenemase-producing Enterobacterales in dogs and cats: a cross-sectional study in Egypt.

One of the most important emerging health problems is the increasing role of animals in the rapid global rise in resistance to last-resort antibiotics, such as carbapenems. However, there is limited information on the role of pet animals in harboring and spreading pandrug-resistant (PDR) carbapenemase-producing Enterobacterales (CPE), especially in Egypt. This cross-sectional study was conducted to screen for CPE in healthy and diseased pets using phenotypic and molecular methods and the NG-Test CARBA 5 immunochromatographic assay. Rectal swabs were collected from 62 dogs and 48 cats, incubated overnight in tryptic soy broth containing 10 μg of meropenem disc and subsequently cultured on MacConkey agar supplemented with meropenem (1 mg/L). Sixty-six isolates (60.6%), including 56 Klebsiella pneumoniae, seven Escherichia coli, and three K. oxytoca isolates, were confirmed to be carbapenem-resistant Enterobacterales (CRE) by the disc diffusion method, broth microdilution test, CNPt-direct, and PCR assay targeting carbapenemase genes. Forty-three (65.2%) dogs and 23 (34.8%) cats carried CPE. Of these, 35 (70.0%) were healthy (including 27 dogs and 8 cats) and 31 (52.5%) were diseased (including 16 dogs and 15 cats). bla OXA-181 was the most common gene detected (42/66, 63.6%), followed by bla IMP (40/66, 60.6%), bla OXA-48-like (29/66, 43.9%), bla KPC and bla VIM (20/66, 30.3% each), and bla NDM (17/66, 25.8%). The identified genotypes were bla KPC-2, bla IMP-1, bla VIM-1, bla NDM-1, and bla NDM-5. The CARBA 5 assay showed higher sensitivity and specificity for the detection of NDM, OXA and KPC than that for VIM and IMP genes. Antimicrobial resistance profiles of CRE isolates revealed 20 PDR, 30 extensively drug-resistant (XDR), and 16 multidrug-resistant (MDR) phenotypes. This study provides evidence of colonization with PDR CPE in dogs and cats. To manage the infection or colonization of pets in veterinary clinical settings, extended surveillance systems should be considered, and the use of critical antibiotics should be strictly controlled.

A systematic review and meta-analysis of carbapenem resistance and its possible treatment options with focus on clinical Enterobacteriaceae: Thirty years of development in Pakistan

BackgroundCarbapenem resistance is epidemic worldwide, these last resort antimicrobials are listed in the WHO ‘watch group’ with higher resistance potential. During the years 2017-18 Pakistan Antimicrobial Resistance Surveillance System reported an increase in carbapenem resistance. However, a comprehensive information on prevalence and molecular epidemiology of carbapenem resistance in Pakistan is not available. This systematic review and meta-analysis is aimed to report the current carbapenem resistance situation in Pakistan and its treatment options. MethodsIn this systematic review and meta-analysis, we investigated the pooled prevalence (PPr) of carbapenem resistance in Enterobacteriaceae and non-Enterobacteriaceae by organizing available data, from Web of Science and PubMed by April 2, 2020, in various groups and subgroups including species, years, provinces, extended spectrum β-lactamase production, clinical presentation, carbapenemase and metallo-β-lactamase production, and New Delhi metallo-β-lactamase (NDM) prevalence. Literature review was updated for the studies publisehd by December 07, 2023. Moreover, we descriptively reviewed the molecular epidemiology of carbapenem resistance in Enterobacteriaceae and non-Enterobacteriaceae in Pakistan. Lastly, we statistically explored different treatment options available for carbapenem resistant infections. We used R package ‘metafor’ for performing meta-analysis and influence diagnostics and determining treatment options. ResultsFrom two academic databases Web of Science and PubMed we identified 343 studies. Eighty-eight studies were selected for the systematic review and meta-analysis. Seventy-four studies were selected for phenotypic analysis, 36 for genotypic analysis, and 31 for available treatment options. PPr-ID of 12% [0.12 (0.07, 0.16)] was observed for phenotypic carbapenem resistance in Enterobacteriaceae with more prevalence recorded in Klebsiella pneumoniae 24% [0.24 (0.05, 0.44)] followed by 9% [0.09 (−0.03, 0.20)] in Escherichia coli. During the last two decades we observed a striking increase in carbapenem resistance PPr i.e., from 0% [0.00 (−0.02, 0.03)] to 36% [0.36 (0.17, 0.56)]. blaNDM with PPr 15% [0.15 (0.06, 0.23)] in naive isolates was found to be the fundamental genetic determinant for carbapenem resistance in Enterobacteriaceae in Pakistan. Polymyxin B, colistin, tigecycline, and fosfomycin were identified as the suggested treatment options available for multidrug resistant infections not responding to carbapenems. Various studies reported carbapenem resistance from human, animal, and environment sources. ConclusionIn conclusion, we found that NDM-1 producing carbapenem resistant Enterobacteriaceae are increasing in Pakistan. Meta-analysis showed that metallo-β-lactamases producing E. coli ST405 and K. pneumoniae sequence type11 are the major resistant clones. Number of reported studies in various subgroups and inconsistency in following CLSI guidelines are the potential limitations of this meta-analysis. A National antimicrobial resistance (AMR) surveillance strategy based on One Health is urgently needed to check any future AMR crisis in Pakistan.