Risk Factors Associated with Carbapenemase Producing Carbapenem-Resistant Enterobacteriaceae (CP-CRE) Positive Cultures in a Cohort of U.S. Veterans

Incidence, risk factors and clinical outcome of multidrug-resistant organisms after heart transplantation

BACKGROUND

Transplant recipients commonly harbor multidrug-resistant organisms (MDROs), as a result of frequent hospital admissions and increased exposure to antimicrobials and invasive procedures.

AIM

To investigate the impact of patient demographic and clinical characteristics on MDRO acquisition, as well as the impact of MDRO acquisition on intensive care unit (ICU) and hospital length of stay, and on ICU mortality and 1-year mortality post heart transplantation.

METHODS

This retrospective cohort study analyzed 98 consecutive heart transplant patients over a ten-year period (2013-2022) in a single transplantation center. Data was collected regarding MDROs commonly encountered in critical care.

RESULTS

Among the 98 transplanted patients (70% male), about a third (32%) acquired or already harbored MDROs upon transplantation (MDRO group), while two thirds did not (MDRO-free group). The prevalent MDROs were Acinetobacter baumannii (14%), Pseudomonas aeruginosa (12%) and Klebsiella pneumoniae (11%). Compared to MDRO-free patients, the MDRO group was characterized by higher body mass index (P = 0.002), higher rates of renal failure (P = 0.017), primary graft dysfunction (10% vs 4.5%, P = 0.001), surgical re-exploration (34% vs 14%, P = 0.017), mechanical circulatory support (47% vs 26% P = 0.037) and renal replacement therapy (28% vs 9%, P = 0.014), as well as longer extracorporeal circulation time (median 210 vs 161 min, P = 0.003). The median length of stay was longer in the MDRO group, namely ICU stay was 16 vs 9 d in the MDRO-free group (P = 0.001), and hospital stay was 38 vs 28 d (P = 0.006), while 1-year mortality was higher (28% vs 7.6%, log-rank-χ 2: 7.34).

CONCLUSION

Following heart transplantation, a predominance of Gram-negative MDROs was noted. MDRO acquisition was associated with higher complication rates, prolonged ICU and total hospital stay, and higher post-transplantation mortality.

Sepsis Stewardship: The Puzzle of Antibiotic Therapy in the Context of Individualization of Decision Making

The main recent change observed in the field of critical patient infection has been universal awareness of the need to make better use of antimicrobials, especially for the most serious cases, beyond the application of simple and effective formulas or rigid protocols. The increase in resistant microorganisms, the quantitative increase in major surgeries and interventional procedures in the highest risk patients, and the appearance of a significant number of new antibiotics in recent years (some very specifically directed against certain mechanisms of resistance and others with a broader spectrum of applications) have led us to shift our questions from "what to deal with" to "how to treat". There has been controversy about how best to approach antibiotic treatment of complex cases of sepsis. The individualized and adjusted dosage, the moment of its administration, the objective, and the selection of the regimen are pointed out as factors of special relevance in a critically ill patient where the frequency of resistant microorganisms, especially among the Enterobacterales group, and the emergence of multiple and diverse antibiotic treatment alternatives have made the appropriate choice of antibiotic treatment more complex, requiring a constant updating of knowledge and the creation of multidisciplinary teams to confront new infections that are difficult to treat. In this article, we have reviewed the phenomenon of the emergence of resistance to antibacterials and we have tried to share some of the ideas, such as stewardship, sparing carbapenems, and organizational, microbiological, pharmacological, and knowledge tools, that we have considered most useful and effective for individualized decision making that takes into account the current context of multidrug resistance. The greatest challenge, therefore, of decision making in this context lies in determining an effective, optimal, and balanced empirical antibiotic treatment.

Proton pump inhibitors increase the risk of carbapenem-resistant Enterobacteriaceae colonization by facilitating the transfer of antibiotic resistance genes among bacteria in the gut microbiome

Carbapenem-resistant Enterobacteriaceae (CRE) pose a global health threat; however, there is still limited understanding of the risk factors and underlying mechanisms of CRE colonization in the gut microbiome. We conducted a matched case-control study involving 282 intensive care unit patients to analyze influencing covariates on CRE colonization. Subsequently, their effects on the gut microbiome were analyzed in a subset of 98 patients (47 CRE carriers and 51 non-CRE carriers) using whole metagenome sequences. The concomitant use of proton pump inhibitors (PPIs) and antibiotics was a significant risk factor for CRE colonization. The gut microbiome differed according to PPI administration, even within the CRE and non-CRE groups. Moreover, the transfer of mobile genetic elements (MGEs) harboring carbapenem resistance genes (CRGs) between bacteria was higher in the PPI-treated group than in the PPI-not-treated group among CRE carriers. The concomitant use of PPIs and antibiotics significantly alters the gut microbiome and increases the risk of CRE colonization by facilitating the transfer of CRGs among bacteria of the gut microbiome. Based on these findings, improved stewardship of PPIs as well as antibiotics can provide strategies to reduce the risk of CRE colonization, thereby potentially improving patient prognosis.

Epidemiological Characteristics of Carbapenem-Resistant Enterobacterales in Japan: A Nationwide Analysis of Data from a Clinical Laboratory Center (2016-2022)

In Japan, nationwide epidemiological surveys on carbapenem-resistant Enterobacterales (CREs), including comprehensive information, are scarce, with most data available only through public reports. This study analyzed data on the Enterobacterales family collected from nationwide testing centers between January 2016 and December 2022, focusing on isolates that met the criteria for CRE in Japan based on drug susceptibility. We investigated 5,323,875 Enterobacterales isolates of 12 different species; among 4696 (0.09%) CRE strains, the proportion of major CRE isolates was as follows: Escherichia coli, 31.3%; Klebsiella pneumoniae, 28.0%; Enterobacter cloacae, 18.5%; and Klebsiella aerogenes, 6.7%. Moreover, over a 7-year period, Providencia rettgeri, E. cloacae, K. aerogenes, and K. pneumoniae demonstrated relatively high CRE percentages of 0.6% (156/26,185), 0.47% (869/184,221), 0.28% (313/110,371), and 0.17% (1314/780,958), respectively. The number of CRE strains isolated from different samples was as follows: urine, 2390; respiratory specimens, 1254; stool, 425; blood, 252; others, 375. In the broader context, including colonization, the predominant isolates of CREs collected at nationwide testing centers are E. coli and K. pneumoniae. Furthermore, recently, attention has been directed toward less common CRE species, such as Klebsiella oxytoca and Providencia rettgeri, and thus, it might be necessary to continue monitoring these less common species.

Difficult-to-treat resistant gram-negative blood stream infections - the beginning of a superbug era - a prospective observational study

INTRODUCTION

Carbapenem resistant gram-negative bacterial infections are a growing concern worldwide. However, India is already in the era of a shortage of effective antibiotics for the management of these infections. Moreover, Difficult-to-Treat Resistance (DTR) gram-negative infections, which are not much studied, further complicate the scenario. This study emphasized the incidence and outcomes of DTR infections.

METHODOLOGY

This is a single-center prospective observational study. The study included hospitalised patients aged ≥18 years with gram-negative bacterial bloodstream infections (GNBSI). Blood cultures with the growth of contaminants and/or single positive culture taken from the femoral site were excluded. Incidences of DTR infections and outcomes in the form of 30-day mortality were analysed.

RESULTS

Two hundred forty patients with GNBSI episodes were recorded. The Incidence of DTR GNBSI was 37.9% (91/240). Multivariate analysis found that Hospital-acquired infections, ICU admission and mechanical ventilation were independent risk factors for DTR GNBSI. The most common DTR GNB isolates were Klebsiella pneumoniae (31/49, 63.3%) and Acinetobacter baumannii (26/52, 50%). The adjusted relative risk of mortality was remarkably high in DTR GNBSI (aRR 3.9; 95% CI 1.9-7.9) as compared to CR+/DTR- GNBSI (aRR 0.3; 95% CI 0.1-1.0) and ESCR/CS GNBSI (aRR 1.1; 95% CI 0.5-2.4).

CONCLUSION

DTR GNB infections are growing concern in India and this need to be evaluated in multicentric studies. Moreover, DTR GNBSI was associated with significantly higher mortality and there is need of further empowerment of antibiotic stewardship practices.

Carbapenem-Resistant enterobacterales in individuals with and without health care risk factors -Emerging infections program, United States, 2012-2015

BACKGROUND

Carbapenem-resistant Enterobacterales (CRE) are usually healthcare-associated but are also emerging in the community.

METHODS

Active, population-based surveillance was conducted to identify case-patients with cultures positive for Enterobacterales not susceptible to a carbapenem (excluding ertapenem) and resistant to all third-generation cephalosporins tested at 8 US sites from January 2012 to December 2015. Medical records were used to classify cases as health care-associated, or as community-associated (CA) if a patient had no known health care risk factors and a culture was collected <3 days after hospital admission. Enterobacterales isolates from selected cases were submitted to CDC for whole genome sequencing.

RESULTS

We identified 1499 CRE cases in 1194 case-patients; 149 cases (10%) in 139 case-patients were CA. The incidence of CRE cases per 100,000 population was 2.96 (95% CI: 2.81, 3.11) overall and 0.29 (95% CI: 0.25, 0.35) for CA-CRE. Most CA-CRE cases were in White persons (73%), females (84%) and identified from urine cultures (98%). Among the 12 sequenced CA-CRE isolates, 5 (42%) harbored a carbapenemase gene.

CONCLUSIONS

Ten percent of CRE cases were CA; some isolates from CA-CRE cases harbored carbapenemase genes. Continued CRE surveillance in the community is critical to monitor emergence outside of traditional health care settings.

Clinical Risk Factors and Microbiological and Intestinal Characteristics of Carbapenemase-Producing Enterobacteriaceae Colonization and Subsequent Infection

Gastrointestinal colonization with carbapenem-resistant Enterobacteriaceae (CRE) is always a prerequisite for the development of translocated infections. Here, we sought to screen for fecal carriage of CRE and identify the risk factors for CRE colonization as well as subsequent translocated pneumonia in critically ill patients admitted to the intensive care unit (ICU) of a university hospital in China. We further focused on the intestinal flora composition and fecal metabolic profiles in CRE rectal colonization and translocated infection patients. Animal models of gastrointestinal colonization with a carbapenemase-producing Klebsiella pneumoniae (carbapenem-resistant K. pneumoniae [CRKP]) clinical isolate expressing green fluorescent protein (GFP) were established, and systemic infection was subsequently traced using an in vivo imaging system (IVIS). The intestinal barrier, inflammatory factors, and infiltrating immune cells were further investigated. In this study, we screened 54 patients hospitalized in the ICU with CRE rectal colonization, and 50% of the colonized patients developed CRE-associated pneumonia, in line with the significantly high mortality rate. Upon multivariate analysis, risk factors associated with subsequent pneumonia caused by CRE in patients with fecal colonization included enteral feeding and carbapenem exposure. Furthermore, CRKP colonization and translocated infection influenced the diversity and community composition of the intestinal microbiome. Downregulated propionate and butyrate probably play important and multiangle roles in regulating immune cell infiltration, inflammatory factor expression, and mucus and intestinal epithelial barrier integrity. Although the risk factors and intestinal biomarkers for subsequent infections among CRE-colonized patients were explored, further work is needed to elucidate the complicated mechanisms. IMPORTANCE Carbapenem-resistant Enterobacteriaceae have emerged as a major threat to modern medicine, and the spread of carbapenem-resistant Enterobacteriaceae is a clinical and public health problem. Gastrointestinal colonization by potential pathogens is always a prerequisite for the development of translocated infections, and there is a growing need to assess clinical risk factors and microbiological and intestinal characteristics to prevent the development of clinical infection by carbapenem-resistant Enterobacteriaceae.

Colonization with Carbapenem-Resistant Enterobacteriaceae Contributes to Unfavorable Outcomes in End-Stage Liver Disease Patients

Carbapenem-resistant Enterobacteriaceae (CRE) are the highest priority pathogens of the World Health Organization, and their prevalence in end-stage liver disease (ESLD) patients is increasing. CRE colonization is an independent risk factor for CRE infections. We aimed to assess risk factors and explore the relationship between CRE colonization, infection, and prognosis in patients with ESLD. A total of 311 patients with ESLD were screened for CRE colonization by fecal swabs from October 2020 to January 2022. Antimicrobial susceptibility was tested using the broth microdilution method. Carbapenem resistance genes, multilocus sequence type, and capsular serotype were analyzed by polymerase chain reaction (PCR). Seventeen CRE strains were detected, among which the most common was Klebsiella pneumoniae. The CRE colonization rate was 5.5%. Artificial liver support was an independent risk factor for CRE colonization. Compared to the non-CRE colonization group, the colonization group had a higher incidence of CRE infection and a worse prognosis. Furthermore, these strains were not closely related, and all were sensitive to polymyxin and tigecycline. There was a high colonization rate in ESLD patients, and colonization strains were highly diverse. CRE colonization deserves attention in these patients, especially when treated with artificial liver support.

Insights on the performance of phenotypic tests versus genotypic tests for the detection of carbapenemase-producing Gram-negative bacilli in resource-limited settings

Background:

Carbapenemase-producing Gram-negative (CPGN) bacteria impose life-threatening infections with limited treatment options. Rigor and rapid detection of CPGN-associated infections is usually associated with proper treatment and better disease prognosis. Accordingly, this study aimed at evaluating the phenotypic methods versus genotypic methods used for the detection of such pathogens and determining their sensitivity/specificity values.

Methods:

A total of 71 CPGN bacilli (30 Enterobacterales and 41 non-glucose-fermenting bacilli) were tested for the carbapenemase production by the major phenotypic approaches including, the modified Hodge test (MHT), modified carbapenem inactivation method (mCIM), combined disk test by EDTA (CDT) and blue-carba test (BCT). The obtained results were statistically analyzed and correlated to the obtained resistant genotypes that were determined by using polymerase chain reactions (PCR) for the detection of the major carbapenemase-encoding genes covering the three classes (Class A, B, and D) of carbapenemases.

Results:

In comparison to PCR, the overall sensitivity/specificity values for detection of carbapenemase-producing organism were 65.62%/100% for MHT, 68.65%/100% for mCIM, 55.22%/100% for CDT and 89.55%/75% for BCT. The sensitivity/specificity values for carbapenemase-producing Enterobacterales were, 74%100% for MHT, 51.72%/ 100% for mCIM, 62.07%/100% for CDT and 82.75%/100% for BCT. The sensitivity/specificity values for carbapenemase-producing non-glucose fermenting bacilli were, 62.16%/100% for MHT, 81.57%/100% for mCIM, 50/100% for CDT and 94.74%/66.66% for BCT. Considering these findings, BCT possess a relatively high performance for the efficient and rapid detection of carbapenemase producing isolates. Statistical analysis showed significant association (p < 0.05) between bla_NDM and/or bla_VIM genotypes with MHT/CDT; bla_KPC/bla_GIM genotypes with CDT and bla_GIM genotype with BCT.

Conclusion:

The current study provides an update on the performance of the phenotypic tests which are varied depending on the tested bacterial genera and the type of the carbapenemase. The overall sensitivity/specificity values for detection of CPO were 65.62%/100% for MHT, 68.65%/100% for mCIM, 55.22%/100% for CDT and 89.55%/75% for BCT. Based on its respective diagnostic efficiency and rapid turnaround time, BCT is more likely to be recommended in a resource-limited settings particularly, when molecular tests are not available.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12866-022-02660-5.

The role of cefiderocol in clinical practice

Cefiderocol is a new antimicrobial with a chemical structure similar to ceftazidime and cefepime. In this review we will focus on the role of cefiderocol in different clinical scenarios produced by resistant Gram-negative microorganisms, especially to carbapenems. In infections caused by Gram-negative microorganisms, inappropriate antibiotic treatment increased the risk of mortality almost fourfold. In patients with hospital-acquired infection and septic shock; with sepsis and poor functional reserve due to fragility; in immunocompromised patients; and in those with local ecology, individual history of colonization or previous infection and risk factors for carbapenem-resistant Enterobacteriaceae (CRE) such as the presence of chronic multi-morbidities, the best option would be to start an active empirical treatment against gram-negative bacteria resistant to carbapenems and later in 24-36 h with the information obtained from the cultures we could decide on a definitive empirical or directed treatment and avoid unnecessary overuse of these antibiotics. Cefiderocol would be in these cases a good candidate due to its excellent in vitro activity against all classes of beta-lactamase-producing Gram-negatives (including carbapenemase class A, B and D producers), as well as against non-fermenting Gram-negatives such as P. aeruginosa, Acinetobacter spp. and S. maltophilia. It is necessary to optimize the use of new antibiotics such as cefiderocol, guaranteeing the best available treatment to patients while delaying the emergence and spread of resistance.

Epidemiological Characteristics of Carbapenemase Producing Carbapenem-Resistant Enterobacteriaceae Colonization

PURPOSE

This study identified the epidemiological characteristics, including the size and major strains, of carbapenemase-producing carbapenem-resistant Enterobacteriaceae (CP-CRE) and CP-CRE-related factors by comparing the characteristics of patients in the CP-CRE and non-CP-CRE groups and the CP-CRE and non-CRE groups.

METHODS

This secondary data analysis study included 24 patients in the CP-CRE group, 113 patients in the non-CP-CRE group, and 113 in the non-CRE group. The size and type of CP-CRE were analyzed in terms of frequency and percentage, and CP-CRE risk factors were identified using multiple logistic regression analysis.

RESULTS

The rate of CP-CRE positivity among patients with CRE was 17.5%, and the most common causative organism in the CP-CRE group was Klebsiella pneumoniae (81.8%). There were no significant differences between patients in the CP-CRE and non-CP-CRE groups. When compared with the non-CRE group, the isolation of multidrug-resistant organisms except for CRE, particularly vancomycin resistant Enterococcus, was confirmed as a major risk factor.

CONCLUSION

To prevent CP-CRE acquisition, patients with multidrug-resistant organisms require treatment with more thorough adherence to CRE prevention and management guidelines.

Antibiotic susceptibility patterns of viridans group streptococci isolates in the United States from 2010 to 2020

Background

Viridans group streptococci (VGS) are typically part of the commensal flora but can also cause severe invasive diseases such as infective endocarditis. There are limited data available showing antibiotic susceptibility over time for VGS.

Objectives

To evaluate antibiotic susceptibility trends in VGS over time.

Methods

In vitro susceptibility patterns for 33 antibiotics were examined for Streptococcus mitis, Streptococcus oralis, and non-speciated VGS isolates from patients in Veterans Affairs (VA) Medical Centers in the United States between 2010 and 2020. Susceptibility determinations were made by the individual clinical microbiology laboratories and data were retrospectively collected from the VA Corporate Data Warehouse. Susceptibility trends were analysed using Poisson regression.

Results

A total of 14 981 VGS isolates were included of which 19.5%, 0.7% and 79.8% were S. mitis, S. oralis and non-speciated VGS isolates, respectively. Cumulative susceptibility rates across all years were similar between species for ceftriaxone (range: 96.0% to 100%), clindamycin (81.3% to 84.5%), and vancomycin (99.7% to 100%). For penicillin, susceptibility rates were 71.0%, 80.9% and 86.3% for S. mitis, S. oralis and non-speciated isolates, respectively. From 2010 to 2020, susceptibility of non-speciated VGS isolates decreased for erythromycin (P = 0.0674), penicillin (P = 0.0835), and tetracycline (P = 0.0994); though the decrease was only significant for clindamycin (P = 0.0033). For S. mitis, a significant susceptibility rate decrease was observed for erythromycin (P = 0.0112).

Conclusions

Susceptibility rates for some clinically relevant antibiotics declined between 2010 and 2020. This worrisome trend highlights the need to improve antimicrobial stewardship efforts to limit unnecessary antibiotic use and preserve empirical treatment options.