Rising rates of carbapenem-resistant enterobacteriaceae in community hospitals: a mixed-methods review of epidemiology and microbiology practices in a network of community hospitals in the southeastern United States

Preliminary insights on carbapenem resistance in Enterobacteriaceae in high-income and low-/middle-income countries

The emergence of carbapenem-resistant Enterobacteriaceae in the hospital sector as well as in the natural environment is a problem that affects both high-income countries (HICs) and low-/middle-income countries (LMICs). The observed differences in the prevalence of carbapenem-resistant strains between HICs and LMICs can be attributed mainly to antibiotic consumption in healthcare facilities and the quantity of treated wastewater. Hospital wastewater is a major hotspot for the spread of carbapenem-resistant Enterobacteriaceae (CRE) and carbapenem resistance genes (CRGs) between the hospital sector and the environment. In this review article, attempts were made to describe and compare antibiotic consumption in hospitals, antimicrobial concentrations in both hospital and municipal wastewater, and the prevalence of CRE and CRGs in patients and in hospital and municipal wastewater in HICs and LMICs. A review of the literature has shown that carbapenems are more widely used in LMICs, but Saudi Arabia, an HIC, is a country with the highest carbapenem consumption in the world. The results of research conducted in both groups of countries indicate that Klebsiella sp./K. pneumoniae is the most common CRE in samples isolated from patients. Escherichia coli was the dominant pathogen in hospital and municipal wastewater in HICs, whereas Enterobacter spp. were most prevalent in LMICs. An analysis of the prevalence of CRGs demonstrated that the same genes are present in both groups of countries (blaKPC, blaKPC-2, blaVIM, blaVIM-1,2, blaNDM, blaIMP, blaIMP-8, blaOXA-48,181, blaNDM-1,5, blaGES, blaGES-5,6, blaIMI-1). The fact that the same CRGs are most prevalent in countries with different levels of economic development could suggest that these genes have a high potential to persist in the natural environment. These findings underscore the need for enhanced monitoring, effective control techniques, and a better understanding of carbapenem resistance pathways to mitigate public health hazards, notwithstanding the constraints of data analysis.

Susceptibility of various Gram-negative bacteria to antibacterial agents: SMART in China 2019-2020

BACKGROUND

The Study for Monitoring Antimicrobial Resistance Trends (SMART) is an international surveillance program longitudinally monitoring aerobic and facultative Gram-negative bacteria (GNB) involvement in infections and their antimicrobial resistance profiles. Here the incidence and resistance patterns of Chinese GNB isolates from bloodstream infections (BSI), intraabdominal infections (IAI), respiratory tract infections (RTI) and urinary tract infections (UTI) to commonly used antibacterial agents has been updated. 4,975 GNB isolates collected from 22 hospitals across 7 regions of China from 2019 to 2020 were analyzed. Antimicrobial minimum inhibitory concentrations were assessed using broth microdilution, and susceptibility interpretations followed the breakpoints of European Committee on Antimicrobial Susceptibility Testing 2022 or Clinical and Laboratory Standards Institute.

RESULTS

This study affirmed that Escherichia coli (Ec) was the most commonly identified GNB (32.1%) and then Klebsiella pneumoniae (Kp) (25.3%), Pseudomonas aeruginosa (Pa) (13.9%) and Acinetobacter baumannii (10.5%). The detection rates of carbapenem-resistant (CR) Enterobacterales varied across major infection sites, ranging from 10.3% in UTI to 18.9% in RTI. Specifically, the detection rates of CR-Kp and CR-Pa ranged from 16.2% in IAI to 35.8% in UTI and from 16.1% in UTI to 38.0% in RTI, respectively. Extended-spectrum β-lactamases (ESBL)-producing Ec and Kp bacteria exhibited over 91.7% susceptibility to carbapenems and at least 87.8% susceptibility to amikacin and colistin, but showed lower susceptibility to piperacillin/tazobactam (57.5-86.2%), levofloxacin (10.8-39.7%) and aztreonam (15.3-27.6%) across different infection sources. Amikacin showed higher efficacy against CR strains compared to other commonly used antibacterial drugs, with 80.0% susceptibility against CR-Ec and 82.3% susceptibility against CR-Pa, while only 36.3% susceptibility was observed against CR-Kp.

CONCLUSIONS

The study found varying incidences of CR isolates in Chinese hospitals. Treatment options remained limited due to resistance to multiple antibacterial agents. Carbapenems demonstrated effective antimicrobial in vitro activity against ESBL-producing Enterobacterales found in BSI, IAI, UTI and RTI, outperforming broad-spectrum cephalosporins and other β-lactamase inhibitors.

Establishing piperacillin-tazobactam susceptibility in ceftriaxone non-susceptible Enterobacterales: comparing disk diffusion, Etest, and VITEK 2 automated minimal inhibitory concentration measurements vs. broth microdilution

OBJECTIVES

Post-hoc analyses of the MERINO trial highlight the uncertainty associated with establishing piperacillin-tazobactam (PTZ) susceptibility in extended-spectrum beta-lactamase-producing Enterobacterales. Herein, we compare the concordance of susceptibility for PTZ among the VITEK 2, disc diffusion, and Etest with broth microdilution (BMD) as the reference standard.

METHODS

Ninety-four consecutive ceftriaxone non-susceptible Escherichia coli and Klebsiella pneumoniae bloodstream isolates were identified from patients at three hospitals in Montréal, Québec. BMD was used as the reference standard against which disc diffusion, VITEK 2 (AST-N391), and Etest susceptibility testing were compared. Errors were categorized as very major (false susceptible), major (false resistant), and minor (other).

RESULTS

Overall, 68/94 (72.3%) of isolates were susceptible to PTZ by BMD. Disc diffusion made no major or very major errors (0%; 97.5% CI: 0-3.8%). The VITEK 2 system had a major error rate of 2.5% (95% CI: 0.003-0.089%) and a very major error rate of 26.7% (95% CI: 0.08-0.55%); however, all isolates with VITEK 2 minimal inhibitory concentrations (MICs) of ≤4 μg/mL were susceptible. Finally, the Etest had a major error rate of 6.3% (95% CI: 0.02-0.14%), but no very major errors. Combining VITEK 2-determined susceptibility with a second test led to an increase in the number of correctly classified susceptible organisms.

DISCUSSION

The VITEK 2 system, and to a lesser extent the Etest, risk major errors. Used alone, the VITEK 2 system also risks very major errors if the estimated MIC is > 4 μg/mL. Combining VITEK 2 with disc diffusion in isolates with an estimated MIC of 8-16 μg/mL could prevent both major and very major errors.

Prevalence of Carbapenemase Production Among Klebsiella and Escherichia coli Isolated From Urinary Tract Infections

Background and aim Urinary tract infections represent a substantial portion of healthcare-associated infections due to E. coli and Klebsiella. Carbapenems are broad-spectrum antibiotics considered highly effective in treating infections caused by multidrug-resistant bacteria. Carbapenem-resistant Enterobacteriaceae (CRE), including carbapenem-producing E. coli and Klebsiella isolates, have become a major concern as they limit treatment options. The study aims to determine the prevalence of carbapenemase-producing E. coli and Klebsiella while also comparing the effectiveness of two detection methods, namely the modified carbapenem inactivation method (mCIM) and modified Hodge test (MHT). Materials and methods A cross-sectional study was conducted from July 2022 to June 2023 in a tertiary care hospital, in Karad, Satara, India. Three hundred urinary isolates of E. coli (150) and Klebsiella (150) were studied. These isolates were tested for antimicrobial susceptibility testing. Two phenotypic methods, the modified carbapenem inactivation method (mCIM) and the modified Hodge test (MHT), were used to study carbapenemase production. Results Out of three hundred isolates, carbapenemase production was detected in 72 isolates (24%) by the modified Hodge test (MHT) and in 111 isolates (37%) by the modified carbapenem inactivation method (mCIM). Among the MHT-positive isolates, 46 (63.8%) were identified as Klebsiella and 26 (36.1%) as E. coli. In contrast, of the mCIM-positive isolates, 68 (61.2%) were Klebsiella, and 43 (38.7%) were E. coli. A total of 41 Klebsiella (27.33%) and 25 E. coli (16.66%) isolates tested positive by both methods, highlighting variability in detection rates between the two methods. Conclusion This study observed MHT and mCIM to be accurate for the detection of carbapenemase among carbapenem-resistant isolates. However, the mCIM demonstrated greater sensitivity compared to the MHT.

The Rapid Phenotypic Susceptibility Testing in Real-Life Experience: How the MIC Values Impact on Sepsis Fast Diagnostic Workflow

The MIC value definition faithfully reflects antimicrobial sensitivity, profoundly impacting the infection's clinical outcome. Our study aimed to evaluate the Accelerate PhenoTM System in defining the importance of fast phenotypic susceptibility data. A number of 270 monomicrobial samples simultaneously underwent standard procedures and fast protocols after a contemporary Gram stain. Finally, we provided Turn-around Time (TAT) and statistical evaluations. The fast technology required a medium value of 7 h to complete ID and AST profiles. Although there were some spectrum limitations, it revealed an optimal success rate in microbial identification directly from positive blood cultures. The Gram-negative AST reached a 98.9% agreement between the Accelerate Pheno™ System and the standard method. In addition, the Gram-positive AST gathered a 98.7% agreement comparing the same systems. The chance to rapidly provide precise MIC values is one of the last frontiers in clinical microbiology, especially in high-prevalence antimicrobial resistance areas.

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.

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.

Assessing Colistin Resistance by Phenotypic and Molecular Methods in Carbapenem-resistant Enterobacterales in a Tertiary Care Hospital in Pakistan

Introduction

Members of Enterobacterales are very common pathogens, which continue to show resistance to many antibiotics. Carbapenem performed well for some time. Colistin was the final hope for the carbapenem-resistant Enterobacterales, but resistance against it has virtually tied the clinician's hands, especially when it comes to treating critically ill patients.

Purpose

Detection of colistin resistance by the agar method as well as by the polymerase chain reaction (mobilized colistin resistance-1 gene) in carbapenem-resistant Enterobacterales.

Materials and Methods

A cross-sectional study from Dec 2019 to Dec 2020 was conducted at the Department of Microbiology, Army Medical College, National University of Medical Sciences Rawalpindi Pakistan. Antimicrobial susceptibility of Enterobacterales was determined according to the Kirby-Bauer disc diffusion method except for colistin. Colistin agar was used, in concentrations of 2 µg/mL and 4 µg/mL. Results were interpreted according to Clinical and Laboratory Standards Institute guidelines 2020. Mobilized colistin-resistant-1 gene in the carbapenem resistant Enterobacterales was detected by performing real-time polymerase chain reaction assay.

Results

Among the 172 carbapenem-resistant Enterobacterales 18 isolates were resistant using the colistin agar test. Whereas by molecular method colistin resistance was detected among 10 isolates that carried mobilized colistin resistance 1 gene, making the frequency of the MCR-1 gene 5.81%. Seventy percent of isolates were from paired blood samples. Eight patients, from whom the colistin resistant gene was isolated expired.

Conclusion

Colistin resistance is a very serious issue and should not be missed in a clinical microbiology laboratory. The phenotypic agar test method is an excellent option for routine use, as it combines ease of performance with affordable cost. However, molecular methods are essential for the detection of mobilized colistin resistance gene (1-9) for epidemiological purposes.

Characteristics of community-acquired carbapenem-resistant Enterobacterales

BACKGROUND

Community-acquired carbapenem-resistant Enterobacterales (CA-CRE) are an important threat.

METHODS

In CRACKLE-2, we defined patients with CA-CRE as admitted from home, without pre-existing conditions, and a positive culture within 48 h of admission. Healthcare-associated CRE (HA-CRE) were those with the lowest likelihood of community acquisition, not admitted from home and cultured >48 h after admission. Specific genetic markers in carbapenemase-producing Klebsiella pneumoniae were evaluated through random forest modelling.

RESULTS

CA-CRE and HA-CRE were detected in 83 (10%) and 208 (26%) of 807 patients. No significant differences were observed in bacterial species or strain type distribution. K. pneumoniae (204/291, 70%) was the most common CRE species, of these 184/204 (90%) were carbapenemase producers (CPKP). The top three genetic markers in random forest models were kpi_SA15, fimE, and kpfC. Of these, kpi_SA15 (which encodes a chaperone/usher system) was positively associated (OR 3.14, 95% CI 1.13-8.87, P = 0.026), and kpfC negatively associated (OR 0.21, 95% CI 0.05-0.72, P = 0.015) with CA-CPKP.

CONCLUSIONS

Ten percent of CDC-defined CRE were CA. The true proportion of CA-CRE in hospitalized patients is likely lower as patients may have had unrecorded prior healthcare exposure. The kpi_SA15 operon was associated with the CA phenotype.

Antibiotic resistance patterns of carbapenemase-producing Enterobacterales in Mohammed VI University Hospital of Marrakech, Morocco

OBJECTIVES

The emergence and spread of Carbapenem-Resistant Enterobacterales (CRE) has become a growing concern for health services, internationally, nationally, and regionally. In Morocco, the situation is more worrisome as studies on CRE are scarce and/or scattered and/or outdated. As a result, we carried out the present study to determine and update CRE prevalence at Mohammed VI University Hospital of Marrakech, Morocco.

PATIENTS AND METHODS

A cross-sectional prospective study was carried out from March 2018 to March 2020 on 41161 clinical specimens of 23,469 patients suspected of bacterial infections. Enterobacterales strains were isolated following standard bacteriological procedures. Bacterial strains were identified using BD-Phoenix and MALDI-TOF-MS. Antibiotic susceptibility was determined for 14 antibiotics. Carbapenemase production and phenotypic detection were characterized using modified carbapenem inactivation phenotypic and immunochromatographic methods.

RESULTS

All in all, 484 Enterobaterales resistant to at least one carbapenem were recovered. The majority was isolated from the neonatal unit (14%), followed by the urology-nephrology (11%), and plastic surgery departments (10%). K. pneumoniae (n=232) was the most isolated, followed by E. cloacae (n=148), E. coli (n=56), and S. marcescens (n=17). Antibiotic susceptibility profile showed high rates of resistance to ciprofloxacin (75.21%), gentamicin (84.50%), and cotrimoxazole (88.42%). Out of 484 CRE positive cultures, 388 (80.16%) were Carbapenemase-positive. Out of the latter, 170 were metallo-beta-lactamase producers (NDM), 162 OXA-48-like, and 56 both.

CONCLUSION

These findings emphasize the urgent need for control precautions and strict measures to contain and mitigate this issue.

Epidemiological characteristics of carbapenem-resistant Enterobacteriaceae and carbapenem-resistant Acinetobacter baumannii in a tertiary referral hospital in Korea

Objectives

This study aimed to identify the epidemiological characteristics of patients with carbapenem-resistant Enterobacteriaceae and Acinetobacter baumannii (CRE/CRAB) isolates in a tertiary referral hospital in Korea.

Methods

We collected and analyzed data from 528 adults admitted to a tertiary referral hospital from August 1, 2018 to February 29, 2020. The CRE/CRAB isolates were confirmed as being present at the time of patients’ admission or acquired during hospitalization based on their medical records. The t-test, chi-square test, or Fisher exact test and stepwise multiple logistic regression were performed.

Results

While the proportion of community-acquired CRE/CRAB was low (6%), 20% of CRE/CRAB isolates were identified in patients at the time of hospitalization. The risk of CRAB isolation was positively associated with mechanical ventilator use (odds ratio [OR], 3.52; 95% confidence interval [CI], 1.96−6.33) and total parenteral nutrition use (OR, 3.64; 95% CI, 1.87−7.08).

Conclusion

Over 20% of CRE/CRAB isolates in a tertiary referral hospital in Korea were found at the time of patients’ admission. Furthermore, patients with mechanical ventilation and/or total parenteral nutrition tended to acquire CRAB more frequently. Thus, active surveillance for CRE/CRAB at the time of hospitalization is strongly required, particularly for patients who are expected to require mechanical ventilation or total parenteral nutrition.

Clinical Epidemiology of Carbapenem-Resistant Enterobacterales in the Greater Houston Region of Texas: A 6-year Trend and Surveillance Analysis

Objectives:

Carbapenem-resistant Enterobacterales (CRE) remain an urgent public health priority in the United States. CRE poses a major threat to patients in healthcare and a potential risk to the community. This study examined the epidemiological trends, clinical, and microbiological data of CRE in the Greater Houston region of Texas.

Methods:

A multi-institutional retrospective observational study was conducted using surveillance data collected from 2015 to 2020. Predictors of incidence rates of CRE were determined by a negative binomial regression fit using a generalized estimation equation.

Results:

Over a 6-year period, 4236 CRE cases were reported, of which Klebsiella pneumoniae accounted for 84.8%. The results show a steady increase in CRE cases, with a sharp rise since 2018. The majority of carbapenemase-producing Enterobacterales were Klebsiella pneumoniae carbapenemase (KPC)-producing (77.2%), followed by other rare carbapenemases, which includes OXA-48, NDM, IMP, VIM, coproduction of KPC with OXA-48, KPC with NDM, and NDM with OXA-48. Acute care hospitals (ACH) accounted for 68.5% of the source of CRE cases. The incidence rate of CRE cases reported from ACH and long-term acute care (LTAC) facilities was 1.16 times that of long-term care facilities (adjusted rate ratio [ARR] = 1.16, 95% confidence interval [CI]:1.04–1.30). The incidence rate of CRE among patients with indwelling devices was 15% (ARR = 0.85, 95% CI: 0.79–0.92) lower than that of patients without indwelling devices.

Conclusion:

The rise in the rate of CRE cases despite aggressive infection prevention and control strategies in the region is alarming. Evaluating and improving the current infection control strategies may be warranted.

Epidemiology of Antimicrobial Resistance Among Blood and Respiratory Specimens in the United States Using Genotypic Analysis from a Cloud-Based Population Surveillance Network

Background

Antimicrobial resistance (AMR) surveillance is critical in informing strategies for infection control in slowing the spread of resistant organisms and for antimicrobial stewardship in the care of patients. However, significant challenges exist in timely and comprehensive AMR surveillance.

Methods

Using BioFire Pneumonia and Blood Culture 2 Panels data from BioFire Syndromic Trends (Trend), a cloud-based population surveillance network, we described the detection rate of AMR among a US cohort. Data were included from 2019 to 2021 for Gram-positive and -negative organisms and their related AMR genomic-resistant determinants as well as for detections of Candida auris. Regional and between panel AMR detection rate differences were compared. In addition, AMR codetections and detection rate per organism were evaluated for Gram-negative organisms.

Results

A total of 26 912 tests were performed, primarily in the Midwest. Overall, AMR detection rate was highest in the South and more common for respiratory specimens than blood. methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus detection rates were 34.9% and 15.9%, respectively, whereas AMR for Gram-negative organisms was lower with 7.0% CTX-M and 2.9% carbapenemases. In addition, 10 mcr-1 and 4 C auris detections were observed. For Gram-negative organisms, Klebsiella pneumoniae and Escherichia coli were most likely to be detected with an AMR gene, and of Gram-negative organisms, K pneumoniae was most often associated with 2 or more AMR genes.

Conclusions

Our study provides important in-depth evaluation of the epidemiology of AMR among respiratory and blood specimens for Gram-positive and -negative organism in the United States. The Trend surveillance network allows for near real-time surveillance of AMR.

Drug Regimens of Novel Antibiotics in Critically Ill Patients with Varying Renal Functions: A Rapid Review

There is currently an increase in the emergence of multidrug-resistant bacteria (MDR) worldwide, requiring the development of novel antibiotics. However, it is not only the choice of antibiotic that is important in treating an infection; the drug regimen also deserves special attention to avoid underdosing and excessive concentrations. Critically ill patients often have marked variation in renal function, ranging from augmented renal clearance (ARC), defined as a measured creatinine clearance (CrCL) ≥ 130 mL/min*1.73 m², to acute kidney injury (AKI), eventually requiring renal replacement therapy (RRT), which can affect antibiotic exposure. All novel beta-lactam (BLs) and/or beta-lactam/beta-lactamases inhibitors (BL/BLIs) antibiotics have specific pharmacokinetic properties, such as hydrophilicity, low plasma–protein binding, small volume of distribution, low molecular weight, and predominant renal clearance, which require adaptation of dosage regimens in the presence of abnormal renal function or RRT. However, there are limited data on the topic. The aim of this review was therefore to summarize available PK studies on these novel antibiotics performed in patients with ARC or AKI, or requiring RRT, in order to provide a practical approach to guide clinicians in the choice of the best dosage regimens in critically ill patients.

Karunakaran R, Abdul Jabar K, Ponnampalavanar S, Chong CW, Teh CSJ. A retrospective study on molecular epidemiology trends of carbapenem resistant Enterobacteriaceae in a teaching hospital in Malaysia

BACKGROUND

Carbapenem resistant Enterobacteriaceae (CRE) has rapidly disseminated worldwide and has become a global threat to the healthcare system due to its resistance towards "last line" antibiotics. This study aimed to investigate the prevalence of CRE and the resistance mechanism as well as the risk factors associated with in-hospital mortality.

METHODS

A total of 168 CRE strains isolated from a tertiary teaching hospital from 2014-2015 were included in this study. The presence of carbapenemase genes and minimum inhibitory concentration of imipenem, meropenem and colistin were investigated. All carbapenem-resistant Klebsiella pneumoniae (K. pneumoniae) strains were characterised by PFGE. The risk factors of patients infected by CRE associated with in-hospital mortality were determined statistically.

RESULTS

The predominant CRE species isolated was K. pneumoniae. The carbapenemases detected were blaOXA-48, blaOXA-232, blaVIM and blaNDM of which blaOXA-48 was the predominant carbapenemase detected among 168 CRE strains. A total of 40 CRE strains harboured two different carbapenemase genes. A total of seven clusters and 48 pulsotypes were identified among 140 CRKp strains. A predominant pulsotype responsible for the transmission from 2014 to 2015 was identified. Univariate statistical analysis identified that the period between CRE isolation and start of appropriate therapy of more than 3 days was statistically associated with in-hospital mortality.

Risk factors for isolation of carbapenem-resistant Enterobacterales from normally sterile sites and urine

BACKGROUND

Invasive infections caused by carbapenem-resistant Enterobacterales (CRE) are of significant concern in health care settings. We assessed risk factors for a positive CRE culture from a sterile site (invasive infection) compared to isolation from urine in a large patient cohort in Atlanta from August 2011 to December 2015.

METHODS

CRE cases required isolation, from urine or a normally-sterile site, of E. coli, Klebsiella spp., or Enterobacter spp. that were carbapenem-nonsusceptible (excluding ertapenem) and resistant to all third-generation cephalosporins tested. Risk factors were compared between patients with invasive and urinary infections using multivariable logistic regression.

RESULTS

A total of 576 patients had at least 1 incident case of CRE, with 91 (16%) having an invasive infection. In multivariable analysis, the presence of a central venous catheter (OR 3.58; 95% CI: 2.06-6.23) or other indwelling device (OR 2.34; 95% CI: 1.35-4.06), and recent surgery within the last year (OR 1.81; 95% CI: 1.08-3.05) were associated with invasive infection when compared to urinary infection.

DISCUSSION

Health care exposures and devices were associated with invasive infections in patients with CRE, suggesting that targeting indwelling catheters, including preventing unwarranted insertion or encouraging rapid removal, may be a potential infection control intervention.

CONCLUSIONS

Future infection prevention efforts to decrease CRE cases in health care settings should focus on minimizing unnecessary devices.

Early Multicenter Experience With Imipenem-Cilastatin-Relebactam for Multidrug-Resistant Gram-Negative Infections

A multicenter case series of 21 patients were treated with imipenem-cilastatin-relebactam. There were mixed infection sources, with pulmonary infections (11/21,52%) composing the majority. The primary pathogen was Pseudomonas aeruginosa (16/21, 76%), and 15/16 (94%) isolates were multidrug-resistant. Thirty-day survival occurred in 14/21 (67%) patients. Two patients experienced adverse effects.

Changing Epidemiology and Decreased Mortality Associated With Carbapenem-resistant Gram-negative Bacteria, 2000-2017

BACKGROUND

Carbapenem-resistant gram-negative bacteria (CRGNB) continue to present a global healthcare crisis. We aimed to identify emerging trends of CRGNB over nearly 2 decades and describe the impact of CRGNB on patient outcomes.

METHODS

Patients from whom CRGNB were isolated between 2000 and 2017 were included in the study. Carbapenem resistance was defined by the most recent breakpoints and applied across the study period. Patient demographics, clinical characteristics, and outcomes were retrieved from the electronic health record.

RESULTS

A total of 94 888 isolates from 64 422 patients were identified; 9882 (10%) isolates from 4038 patients were carbapenem-resistant. Pseudomonas aeruginosa was the most common CRGNB each year. The second most common CRGNB emerged in waves over time. Carbapenem daily defined doses increased in parallel with CRGNB rates (R2 = 0.8131). The overall 30-day mortality rate was 19%, which decreased from 24% in 2000 to 17% in 2017 (P = .003; R2 = .4330). Among patients with CRGNB bloodstream infections (n = 319), overall 30- and 90-day mortality rates were 27% and 38%, respectively. Charlson score (adjusted odds ratio [aOR], 1.11 per point), intensive care unit residence (aOR, 7.32), and severe liver disease (aOR, 4.8.4) were independent predictors of 30-day mortality, while receipt of transplantation was associated with lower rates of death (aOR, 0.39). Among patients admitted between 2011 and 2017 (n = 2230), 17% died during hospitalization, 32% were transferred to long-term care facilities, and 38% were discharged home.

CONCLUSIONS

CRGNB emerged in waves over time, causing high rates of mortality. Despite increasing rates of CRGNB, overall patient outcomes have improved, suggesting that recognition and novel therapeutics have made a major impact.

Risk Factors for the Acquisition of a blaNDM-5 Carbapenem-Resistant Escherichia coli in a Veterinary Hospital

Carbapenem-resistant Enterobacteriaceae (CRE) are an urgent antibiotic resistant threat. Only sporadic reports of CRE in companion animals have been described. Our objective was to identify risk factors associated with the acquisition of a blaNDM-5 CR-Escherichia coli strain as part of an outbreak investigation at a tertiary veterinary hospital in the United States. A matched case-control study was conducted among companion animals admitted during July 1, 2018, through June 30, 2019. The 15 identified blaNDM-5 CR-E coli cases were matched 1:2 with controls (culture negative for blaNDM-5 CR-E coli) based on species and number of days of hospitalization before bacterial culture sample collection. The association between exposure to various procedures and hospital services and the acquisition of blaNDM-5 CR-E. coli was assessed through conditional logistic regression. Case patients had significantly higher odds of exposure to the anesthesia service (odds ratio [OR] = 12.8, P = .017), the surgical service (OR = 4.0, P = .046), and to endotracheal intubation (OR = 10.0, P = .03). Veterinary hospitals should be aware of the potential for transmission of CRE via anesthetic and surgical procedures, especially those that require the placement of endotracheal tubes.

Associations of delirium with urinary tract infections and asymptomatic bacteriuria in adults aged 65 and older: A systematic review and meta-analysis

Objective

To determine the associations of delirium with urinary tract infection (UTI) and asymptomatic bacteriuria (AB) in individuals aged 65 and older.

Methods

The protocol for this systematic review and meta‐analysis was published on PROSPERO (CRD42020164341). Electronic databases were searched for relevant studies, professional associations and experts in the field were additionally contacted. Studies with control groups reporting associations between delirium and UTI as well as delirium and AB in older adults were included. The random effects model meta‐analysis was conducted using odds ratios (ORs) with 95% confidence intervals (CIs) as effect size measures. The Newcastle‐Ottawa scale was used to rate the studies' quality. Heterogeneity was assessed using the Q and I² tests. The effects of potential moderators were investigated by both subgroup and meta‐regression analyses. The risk of publication bias was evaluated using the funnel plot and Egger's test.

Results

Twenty nine relevant studies (16,618 participants) examining the association between delirium and UTI in older adults were identified. The association between delirium and UTI was found to be significant (OR 2.67; 95% CI 2.12–3.36; p < 0.001) and persisted regardless of potential confounders. The association between delirium and AB in older adults in the only eligible study found (192 participants) was insignificant (OR 1.62; 95% CI 0.57–4.65; p = 0.37). All included studies were of moderate quality.

Conclusion

The results of this study support the association between delirium and UTI in older adults. Insufficient evidence was found to conclude on an association between delirium and AB in this age group. These findings are limited due to the moderate quality of the included studies and a lack of available research on the association between delirium and AB. Future studies should use the highest quality approaches for defining both delirium and UTI and consider AB in their investigations.

High Prevalence of Extended-Spectrum Beta-Lactamases in Escherichia coli Strains Collected From Strictly Defined Community-Acquired Urinary Tract Infections in Adults in China: A Multicenter Prospective Clinical Microbiological and Molecular Study

Objective

The objective of the study was to investigate the antimicrobial susceptibility and extended-spectrum beta-lactamase (ESBL) positive rates of Escherichia coli from community-acquired urinary tract infections (CA-UTIs) in Chinese hospitals.

Materials and Methods

A total of 809 E. coli isolates from CA-UTIs in 10 hospitals (5 tertiary and 5 secondary hospitals) from different regions in China were collected during the period 2016–2017 according to the strict inclusion criteria. Antimicrobial susceptibility testing was carried out by standard broth microdilution method. Isolates were categorized as ESBL-positive, ESBL-negative, and ESBL-uncertain groups according to the CLSI recommended phenotypic screening method. ESBL and AmpC genes were amplified and sequenced on ESBL-positive and ESBL-uncertain isolates.

Results

The antimicrobial agents with susceptibility rates of greater than 95% included imipenem (99.9%), colistin (99.6%), ertapenem (98.9%), amikacin (98.3%), cefmetazole (97.9%), nitrofurantoin (96%), and fosfomycin (95.4%). However, susceptibilities to cephalosporins (varying from 58.6% to 74.9%) and levofloxacin (48.8%) were relatively low. In the phenotypic detection of ESBLs, ESBL-positive isolates made up 38.07% of E. coli strains isolated from CA-UTIs, while 2.97% were ESBL-uncertain. Antimicrobial susceptibilities of imipenem, cefmetazole, colistin, ertapenem, amikacin, and nitrofurantoin against ESBL-producing E. coli strains were greater than 90%. The percentage of ESBL-producing strains was higher in male (53.6%) than in female patients (35.2%) (p < 0.001). CTX-M-14 (31.8%) was the major CTX-M variant in the ESBL-producing E. coli, followed by CTX-M-55 (23.4%), CTX-M-15 (17.5%), and CTX-M-27 (13.3%). The prevalence of carbapenem-resistant E. coli among CA-UTI isolates was 0.25% (2/809).

Conclusion

Our study indicated high prevalence of ESBL in E. coli strains from strictly defined community-acquired urinary tract infections in adults in China. Imipenem, colistin, ertapenem, amikacin, and nitrofurantoin were the most active antimicrobials against ESBL-positive E. coli isolates. bla_CTX–M–14 is the predominant esbl gene in ESBL-producing and ESBL-uncertain strains. Our study indicated that the use of cephalosporins and fluoroquinolone needs to be restricted for empirical treatment of CA-UTIs in China.

Complete Genome Sequence of Klebsiella pneumoniae Podophage Pone

Klebsiella pneumoniae is a Gram-negative pathogen that has become increasingly antibiotic resistant. Phage therapy is potentially a useful approach to controlling this pathogen. Here, we present the genome sequence of the phiKMV-like K. pneumoniae podophage Pone.

Monitoring antibiotic resistance profiles of faecal isolates of Enterobacteriaceae and the prevalence of carbapenem-resistant isolates among food handlers in Kuwait

OBJECTIVES

Carbapenem-resistant Enterobacteriaceae (CRE) have become one of the most challenging problems in infectious diseases worldwide. Unrecognised personnel such as food handlers (FHs) colonised with CRE serve as a reservoir for transmission. This study assessed the prevalence and susceptibility patterns of CRE isolates from FHs working in commercial eateries in the community (CFHs) and healthcare settings (HCFHs) in Kuwait over the period 2016-2018.

METHODS

Representative colonies from faecal samples were identified by API 20E and a VITEK®2 ID System. Susceptibility testing against 21 antibiotics was performed by Etest and agar dilution.

RESULTS

A total of 681 isolates of the family Enterobacteriaceae were isolated from 405 FHs, of which 425 (62.4%) were Escherichia coli and 126 (18.5%) were Klebsiella pneumoniae. The prevalence of CRE among FHs was 7.7% (31/405), comprising 32% CFHs (10/31) and 68% HCFHs (21/31). Ampicillin, tetracycline and cefalotin showed very poor activities against most isolates with resistance rates of 63.3%, 41.7% and 40.8%, respectively. The prevalence of multidrug-resistant (MDR) isolates was 30.5%, including 130 E. coli (30.6%) and 22 K. pneumoniae (17.5%). An alarming level of colistin resistance (11.3%) was noted. A significant proportion of FH isolates (13.2%) exhibited extended-spectrum β-lactamases (ESBL) phenotypes, including 80 E. coli (18.8%) and 5 K. pneumoniae (4.0%).

CONCLUSION

This study revealed that asymptomatic intestinal carriage of CRE, including MDR and ESBL isolates, was relatively common in our community. It is conceivable that FHs may pose a significant risk to consumers for the acquisition and spread of resistant strains.

Carbapenem-Resistant Enterobacterales in Long-Term Care Facilities: A Global and Narrative Review

The emergence of carbapenem-resistant Enterobacterales (CRE) has become a major public health concern. Moreover, its colonization among residents of long-term care facilities (LTCFs) is associated with subsequent infections and mortality. To further explore the various aspects concerning CRE in LTCFs, we conducted a literature review on CRE colonization and/or infections in long-term care facilities. The prevalence and incidence of CRE acquisition among residents of LTCFs, especially in California, central Italy, Spain, Japan, and Taiwan, were determined. There was a significant predominance of CRE in LTCFs, especially in high-acuity LTCFs with mechanical ventilation, and thus may serve as outbreak centers. The prevalence rate of CRE in LTCFs was significantly higher than that in acute care settings and the community, which indicated that LTCFs are a vital reservoir for CRE. The detailed species and genomic analyses of CRE among LTCFs reported that Klebsiella pneumoniae is the primary species in the LTCFs in the United States, Spain, and Taiwan. KPC-2-containing K. pneumoniae strains with sequence type 258 is the most common sequence type of KPC-producing K. pneumoniae in the LTCFs in the United States. IMP-11- and IMP-6-producing CRE were commonly reported among LTCFs in Japan. OXA-48 was the predominant carbapenemase among LTCFs in Spain. Multiple risk factors associated with the increased risk for CRE acquisition in LTCFs were found, such as comorbidities, immunosuppressive status, dependent functional status, usage of gastrointestinal devices or indwelling catheters, mechanical ventilation, prior antibiotic exposures, and previous culture reports. A high CRE acquisition rate and prolonged CRE carriage duration after colonization were found among residents in LTCFs. Moreover, the patients from LTCFs who were colonized or infected with CRE had poor clinical outcomes, with a mortality rate of up to 75% in infected patients. Infection prevention and control measures to reduce CRE in LTCFs is important, and could possibly be controlled via active surveillance, contact precautions, cohort staffing, daily chlorhexidine bathing, healthcare-worker education, and hand-hygiene adherence.

Imipenem/cilastatin/relebactam: A new carbapenem β-lactamase inhibitor combination

PURPOSE

The pharmacology, pharmacokinetics, pharmacodynamics, antimicrobial activity, efficacy, safety, and current regulatory status of imipenem/cilastatin/relebactam are reviewed.

SUMMARY

Imipenem/cilastatin/relebactam is a newly approved anti-infective combination of a well-established β-lactam and a new β-lactamase inhibitor for the treatment of complicated urinary tract infections (cUTIs), including pyelonephritis, and complicated intra-abdominal infections (cIAIs) caused by susceptible gram-negative bacteria in patients 18 years of age or older with limited or no alternative treatment options. The antibiotic is also indicated for the treatment of hospital-acquired bacterial pneumonia (HABP) and ventilator-associated bacterial pneumonia (VABP). The antibiotic is active in vitro against a wide range of pathogens, including multidrug-resistant (MDR) Pseudomonas aeruginosa and carbapenem-resistant Enterobacterales (CRE) such as Klebsiella pneumoniae carbapenemase. The addition of relebactam does not restore the activity of imipenem against metallo-β-lactamase (MBL)-producing Enterobacterales and carbapenem-resistant Acinetobacter baumannii. Two phase 3 clinical trials of imipenem/cilastatin/relebactam were conducted. In the RESTORE-IMI 1 trial, the efficacy and safety of imipenem/cilastatin/relebactam was found to be comparable to that of imipenem/cilastatin plus colistin for the treatment of infections caused by imipenem-nonsusceptible gram-negative bacteria in patients with HABP/VABP, cUTIs, and cIAIs, with a significantly lower incidence of nephrotoxicity reported with the new antibiotic. The RESTORE-IMI 2 trial demonstrated the noninferiority of imipenem/cilastatin/relebactam to piperacillin/tazobactam for the treatment of HABP/VABP. Commonly reported adverse events in clinical trials included anemia, elevated liver enzymes, electrolyte imbalances, nausea, vomiting, diarrhea, headache, fever, phlebitis and/or infusion-site reactions, and hypertension.

CONCLUSION

Imipenem/cilastatin/relebactam is a new β-lactam/β-lactamase inhibitor combination with activity against MDR gram-negative bacteria, including many CRE but excluding MBL-producing Enterobacterales and carbapenem-resistant Acinetobacter baumannii. It is approved for the treatment of cUTIs, cIAIs, and HABP/VABP.

Carbapenem-Resistant Enterobacteriaceae-Implications for Treating Acute Leukemias, a Subgroup of Hematological Malignancies

Acute leukemias (AL) are a group of aggressive malignant diseases associated with a high degree of morbidity and mortality. Patients with AL are highly susceptible to infectious diseases due to the disease itself, factors attributed to treatment, and specific individual risk factors. Enterobacteriaceae presence (e.g., Klebsiella pneumonia and Escherichia coli) is a frequent cause of bloodstream infections in AL patients. Carbapenem-resistant Enterobacteriaceae (CRE) is an emerging health problem worldwide; however, the incidence of CRE varies greatly between different regions. Carbapenem resistance in Enterobacteriaceae is caused by different mechanisms, and CRE may display various resistance profiles. Bacterial co-expression of genes conferring resistance to both broad-spectrum β-lactam antibiotics (including carbapenems) and other classes of antibiotics may give rise to multidrug-resistant organisms (MDROs). The spread of CRE represents a major treatment challenge for clinicians due to lack of randomized clinical trials (RCTs), a limited number of antibiotics available, and the side-effects associated with them. Most research concerning CRE infections in AL patients are limited to case reports and retrospective reviews. Current research recommends treatment with older antibiotics, such as polymyxins, fosfomycin, older aminoglycosides, and in some cases carbapenems. To prevent the spread of resistant microbes, it is of pivotal interest to implement antibiotic stewardship to reduce broad-spectrum antibiotic treatment, but without giving too narrow a treatment to neutropenic infected patients.

Molecular characterization of carbapenem-resistant Enterobacterales in thirteen tertiary care hospitals in Saudi Arabia

BACKGROUND

Carbapenems are the antibiotics of last-resort for the treatment of bacterial infections caused by multidrug-resistant organisms. The emergence of resistance is a critical and worrisome problem for clinicians and patients. Carbapenem-resistant Enterobacterales (CRE) are spreading globally, are associated with an increased frequency of reported outbreaks in many regions, and are becoming endemic in many others.

OBJECTIVES

Determine the molecular epidemiology of CRE isolates from various regions of Saudi Arabia to identify the genes encoding resistance and their clones for a better understanding of the epidemio-logical origin and national spread.

DESIGN

Multicenter, cross-sectional, laboratory-based study.

SETTING

Samples were collected from 13 Ministry of Health tertiary-care hospitals from five different regions of Saudi Arabia.

METHODS

Isolates were tested using the GeneXpert molecular platform to classify CRE.

MAIN OUTCOME MEASURES

Prevalence of various types of CRE in Saudi Arabia.

SAMPLE SIZE

519 carbapenem-resistant isolates.

RESULT

Of 519 isolates, 440 (84.7%) were positive for CRE, with Klebsiella pneumoniae (410/456, 90%) being the most commonly isolated pathogen. The distribution of the CRE-positive K pneumoniae resistance genes was as follows: OXA-48 (n=292, 71.2%), NDM-1 (n=85, 20.7%), and NDM+OXA-48 (n=33, 8%). The highest percentage of a single blaOXA-48 gene was detected in the central and eastern regions (77%), while the blaNDM-gene was the predominant type in the northern region (27%). The southern regions showed the lowest percentages for harboring both blaOXA-48 and blaNDM genes (4%), while the western region isolates showed the highest percentage of harboring both genes (14%).

CONCLUSION

The results illustrate the importance of molecular characterization of CRE isolates for patient care and infection prevention and control. Larger multicenter studies are needed to critically evaluate the risk factors and trends over time to understand the dynamics of spread and effective methods of control.

LIMITATIONS

Lack of phenotypic susceptibility and clinical data.

CONFLICT OF INTEREST

None.

Epidemiology of carbapenem-resistant Enterobacteriaceae in hospitals of a large healthcare system in Miami, Florida from 2012 to 2016: Five years of experience with an internal registry

BACKGROUND

Carbapenem-resistant Enterobacteriaceae (CRE) is an urgent public health threat globally. Limited data are available regarding the epidemiology of CRE in South Florida. We describe the epidemiology of CRE within a large public healthcare system in Miami, FL, the experience with an internal registry, active surveillance testing, and the impact of infection prevention practices.

METHODS

Retrospective cohort study in 4 hospitals from a large healthcare system in Miami-Dade County, FL from 2012 to 2016. The internal registry included all CRE cases from active surveillance testing from rectal and/or tracheal screening occurring in the intensive care units of 2 of the hospitals and clinical cultures across the healthcare system. All CRE cases were tagged in the electronic medical record and automatically entered into a platform for automatic infection control surveillance. The system alerted about new cases, readmissions, and transfers.

RESULTS

A total of 371 CRE cases were identified. The overall prevalence was 0.077 cases per 100 patient-admissions; the admission prevalence was 0.019 per 100 patient-admissions, and the incidence density was 1.46 cases per 10,000 patient-days. Rates increased during the first 3 years of the study and declined later to a lower level than at the beginning of study period.

CONCLUSIONS

Active surveillance testing and the use of an internal registry facilitated prompt identification of cases contributing to control increasing rates of CRE by rapid implementation of infection prevention strategies.

Clinical and Microbiological Characteristics of Community-Onset Carbapenem-Resistant Enterobacteriaceae Isolates

Objective

The aim of this study was to investigate the clinical and microbiological features of community-onset CRE (CO-CRE) obtained from outpatients at a tertiary hospital in China.

Patients and Methods

We isolated 64 CRE strains from outpatients and divided them into three groups: 36 hospital-acquired CRE (HA-CRE), 28 CO-CRE including 15 community-acquired CRE (CA-CRE) and 13 healthcare-associated CRE (HCA-CRE). Clinical information was collected. The antibiotic susceptibilities of the 28 CO-CRE strains were tested. Whole-genome sequencing (WGS) was conducted, and then drug resistance gene analysis was performed. CgMLST and SNP comparisons were used to analyze the genomic relationship with E. coli and K. pneumoniae strains, respectively.

Results

In this study, the 28 CO-CRE isolates included K. pneumoniae (53.6%), E. coli (28.6%), E. cloacae (7.1%), C. freundii (7.1%) and E. asburiae (3.6%). The CO-CRE isolates were mainly isolated from urine samples (75%). The ceftazidime/avibactam resistance rate of community-onset E. coli was significantly higher than that of community-onset K. pneumoniae, while the aztreonam, ciprofloxacin, levofloxacin, and chloramphenicol resistance rates were significantly lower (P<0.05). Thirteen of the 15 K. pneumoniae strains belonged to ST11 containing bla_KPC-2. Correspondingly, 8 E. coli strains belonged to 7 STs, and they all were NDM producers. K. pneumoniae belonged to two major clusters, while E. coli was sporadic. The number of SNPs separating ST11 K. pneumoniae isolates ranged from 7 to 2154.

Conclusion

Community-onset CRE is not rare, and the dissemination of E. coli was sporadic while K. pneumoniae was clonal spread with similar STs as HA-CRE. Active surveillance of CRE in the community setting is in demand.

Evaluation of patient risk factors for infection with carbapenem-resistant Enterobacteriaceae

BACKGROUND

To evaluate risk factors for infection or colonization with carbapenem-resistant Enterobacteriaceae (CRE) to develop an algorithm for targeted CRE screening.

METHODS

We conducted a case-control study of 50 CRE-positive cases and 100 CRE-negative controls to identify risk factors that were significant for CRE infection or colonization. The setting was at an acute care academic hospital. Patients who tested positive for CRE or other microbiological laboratory tests during the study period were included. We reviewed medical records of 50 patients who were CRE-positive and 100 matched controls who had a non-CRE culture at a similar anatomic site within the closest time period to the case's culture date. Risk factors were assessed using logistic regression with SAS 9.4, observing the 95% confidence interval (CI) to determine significance.

RESULTS

Significant risk factors for CRE infection or colonization included the use of fluoroquinolones (odds ratio [OR], 3.75; 95% CI, 1.35, 10.38) and cephalosporins (OR, 2.37; 95% CI, 1.17, 4.86). In addition, undergoing an invasive procedure with a scope device was also a significant risk factor for our participants (OR, 4.57; 95% CI, 1.31, 16.02). Significance of these risk factors varied within the community-acquired and hospital-acquired cases.

CONCLUSIONS

Our results suggest that exposure to certain antimicrobials and invasive procedures with a scope device (endoscopic retrograde cholangiopancreatography, duodenal endoscope) are risk factors for CRE. The findings of significant differences in antimicrobials received highlight the necessity to understand antimicrobial stewardship in the development of CRE colonization and infection. Along with antibiotics, inaccessibility to components within scope devices may be increasing the risk of CRE spread.

A coup d'état by NDM-producing Klebsiella pneumoniae overthrows the major bacterial population during KPC-directed therapy

The objective of this study was to utilize a co-culture hollow-fiber infection model (HFIM) to characterize the interplay between a small, difficult-to-detect, New Delhi metallo-β-lactamase-producing Klebsiella pneumoniae (NDM-Kp) minor population and a larger K. pneumoniae carbapenemase (KPC)-producing K. pneumoniae population in the presence of KPC-directed antibacterial therapy. Selective plating onto agar with ceftazidime-avibactam was used to track the density of the NDM-Kp population. Susceptibility testing and the Verigene System failed to identify the small initial NDM-Kp population. However, a ceftazidime-avibactam Etest detected resistant colonies that were confirmed to be NDM-Kp. In the HFIM, all of the investigated drug regimens caused regrowth within 24 h and resulted in >10⁹ CFU/mL of NDM-Kp. Our study demonstrates that the HFIM is a powerful tool for studying the population dynamics of multiple pathogens during antimicrobial exposure and also highlights that difficult-to-detect minor populations of drug-resistant bacteria may cause treatment failure without appropriate antibacterial therapy.

Contributing Factors to the Clinical and Economic Burden of Patients with Laboratory-Confirmed Carbapenem-Nonsusceptible Gram-Negative Respiratory Infections

PURPOSE

This study examined patient- and hospital-level predictor variables that contribute to worse clinical and economic outcomes in patients with carbapenem-nonsusceptible respiratory infections.

PATIENTS AND METHODS

Electronic data (January 2013 to September 2015) were from 78 US hospitals. Nonduplicate, gram-negative respiratory isolates were considered carbapenem-nonsusceptible if they tested resistant/intermediate to imipenem, meropenem, doripenem, or ertapenem. Potential predictors of outcomes (in-hospital mortality, 30-day readmission, length of stay [LOS], hospital total cost, and net gain/loss per patient) were examined using univariate analysis and generalized linear mixed models. Statistical significance and model goodness-of-fit criteria were used to identify significant predictors.

RESULTS

A total of 1488 carbapenem-nonsusceptible respiratory patients were identified. Overall, the mortality rate was 13.7%, 30-day readmission rate was 20.6%, mean LOS was 20 days, mean total cost was $54,158, and mean net loss was $139 per patient. Our models showed that hospital-onset infection, higher clinical severity, mechanical ventilation/intensive care unit status, polymicrobial infection, and underlying diseases were all significant predictors for mortality, LOS, and total cost. Hospital-onset infections were also associated with a significantly greater net loss (P≤.01), and underlying disease significantly impacted readmissions (P=.03). The number of prior admissions, hospital characteristics, and payer type were also found to significantly impact measured outcomes.

CONCLUSION

Carbapenem-nonsusceptible respiratory infections are associated with a considerable clinical and economic burden. The impact of hospital-onset infections on both clinical and economic outcomes highlights the continued need for action on this modifiable risk factor through antimicrobial stewardship and optimal therapy, thereby reducing the burden in this patient population.

Attributable burden in patients with carbapenem-nonsusceptible gram-negative respiratory infections

Objective

We aimed to describe the clinical and economic burden attributable to carbapenem-nonsusceptible (C-NS) respiratory infections.

Methods

This retrospective matched cohort study assessed clinical and economic outcomes of adult patients (aged ≥18 years) who were admitted to one of 78 acute care hospitals in the United States with nonduplicate C-NS and carbapenem-susceptible (C-S) isolates from a respiratory source. A subset analysis of patients with principal diagnosis codes denoting bacterial pneumonia or other diagnoses was also conducted. Isolates were classified as community- or hospital-onset based on collection time. A generalized linear mixed model method was used to estimate the attributable burden for mortality, 30-day readmission, length of stay (LOS), cost, and net gain/loss (payment minus cost) using propensity score-matched C-NS versus C-S cohorts.

Results

For C-NS cases, mortality (25.7%), LOS (29.4 days), and costs ($81,574) were highest in the other principal diagnosis, hospital-onset subgroup; readmissions (19.4%) and net loss (-$9522) were greatest in the bacterial pneumonia, hospital-onset subgroup. Mortality and readmissions were not significantly higher for C-NS cases in any propensity score-matched subgroup. Significant C-NS–attributable burden was found for both other principal diagnosis subgroups for LOS (hospital-onset: 3.7 days, P = 0.006; community-onset: 1.5 days, P<0.001) and cost (hospital-onset: $12,777, P<0.01; community-onset: $2681, P<0.001).

Conclusions

Increased LOS and cost burden were observed in propensity score-matched patients with C-NS compared with C-S respiratory infections; the C-NS–attributable burden was significant only for patients with other principal diagnoses.

Epidemiology of Carbapenem-resistant Enterobacteriaceae in Egyptian intensive care units using National Healthcare-associated Infections Surveillance Data, 2011-2017

Objective

To describe the epidemiology of carbapenem-resistant Enterobacteriaceae (CRE) healthcare-associated infections (HAI) in Egyptian hospitals reporting to the national HAI surveillance system.

Methods

Design: Descriptive analysis of CRE HAIs and retrospective observational cohort study using national HAI surveillance data. Setting: Egyptian hospitals participating in the HAI surveillance system. The patient population included patients admitted to the intensive care unit (ICU) in participating hospitals. Enterobacteriaceae HAI cases were Klebsiella, Escherichia coli, and Enterobacter isolates from blood, urine, wound or respiratory specimen collected on or after day 3 of ICU admission. CRE HAI cases were those resistant to at least one carbapenem. For CRE HAI cases reported during 2011-2017, a hospital-level and patient-level analysis were conducted using only the first CRE isolate by pathogen and specimen type for each patient. For facility, microbiology, and clinical characteristics, frequencies and means were calculated among CRE HAI cases and compared with carbapenem-susceptible Enterobacteriaceae HAI cases through univariate and multivariate logistic regression using STATA 13.

Results

There were 1598 Enterobacteriaceae HAI cases, of which 871 (54.1%) were carbapenem resistant. The multivariate regression analysis demonstrated that carbapenem resistance was associated with specimen type, pathogen, location prior to admission, and length of ICU stay. Between 2011 and 2017, there was an increase in the proportion of Enterobacteriaceae HAI cases due to CRE (p-value = 0.003) and the incidence of CRE HAIs (p-value = 0.09).

Conclusions

This analysis demonstrated a high and increasing burden of CRE in Egyptian hospitals, highlighting the importance of enhancing infection prevention and control (IPC) programs and antimicrobial stewardship activities and guiding the implementation of targeted IPC measures to contain CRE in Egyptian ICU's .

Association between carbapenem-resistant Enterobacteriaceae and death: A systematic review and meta-analysis

BACKGROUND

Carbapenem-resistant Enterobacteriaceae (CRE) has emerged in health care facilities around the world. Several studies demonstrated data regarding clinical outcomes for CRE infections including death. This systematic review and meta-analysis summarized literature discussing association between CRE and mortality.

METHODS

A systematic literature review was performed by searching EMBASE, International Pharmaceutical Abstract databases, PubMed, and Scopus and to identify studies that assessed the association between CRE and death published from April 2012 to October 2017. A meta-analysis was performed using a random effect model. Heterogeneity was assessed using the I²-statistic.

RESULTS

Twenty-one studies were included in this meta-analysis. The underlying populations were moderately heterogeneous (I² = 60%; P = .01). Pooled risk estimates from 9 studies revealed a significant association between CRE and death (pooled-adjusted odds ratio: 2.85; 95% confidence interval: 1.88, 4.30). The unadjusted variable pooled from 18 studies demonstrated a significant association between CRE and death (pooled-unadjusted odds ratio: 3.73; 95% confidence interval: 2.02, 6.88).

DISCUSSION

The finding that CRE infection was positively associated with death agreed with the previous meta-analysis of studies published before April 2012.

CONCLUSIONS

This meta-analysis found that CRE was associated with increased risk of death. Our analysis implies a need for strict infection control measures.

Trends in resistant Enterobacteriaceae and Acinetobacter species in hospitalized patients in the United States: 2013-2017

BACKGROUND

Trends in antimicrobial resistance help inform infection control efforts. We examined trends in resistance for Enterobacteriaceae and Acinetobacter spp. from 2013 to 2017 in hospitalized US patients.

METHODS

We analyzed antimicrobial susceptibility of non-duplicate isolates in hospitalized patients (not limited to hospital-acquired infections) in the US BD Insights Research Database. Resistance profiles of interest were extended-spectrum beta-lactamase (ESBL)-producing, multidrug resistant (MDR), and carbapenem-nonsusceptible (Carb-NS) phenotypes of Enterobacteriaceae, and MDR and Carb-NS Acinetobacter spp. Time series models were used to evaluate the patterns of resistance trends in rate per 100 hospital admissions and proportion per isolates tested.

RESULTS

More than 1 million Enterobacteriaceae isolates were obtained from 411 hospitals; 12.05% were ESBL, 1.21% Carb-NS, and 7.08% MDR. Urine was the most common source. For Acinetobacter spp. (n = 19,325), 37.48% were Carb-NS, 47.66% were MDR, and the most common source was skin/wound cultures. Trend analyses showed that the rates of ESBL and Carb-NS Enterobacteriaceae per 100 hospital admissions increased significantly between 2013 and 2017. Rates of MDR Enterobacteriaceae and Carb-NS and MDR Acinetobacter spp. decreased during this time period. Trends in proportions of resistant isolates generally mirrored trends in rates per 100 hospital admissions. MDR Enterobacteriaceae and Carb-NS and MDR Acinetobacter spp. were more common in winter than summer.

CONCLUSIONS

In this large-scale study of patients in US hospitals, rates of ESBL and Carb-NS Enterobacteriaceae per 100 hospital admissions increased between 2013 and 2017. MDR Enterobacteriaceae and MDR and Carb-NS Acinetobacter spp. isolates decreased over this period. These data support continuing infection control and stewardship efforts and the development of new therapeutic options.

New Delhi Metallo-β-lactamase and other mechanisms of carbapenemases among Enterobacteriaceae in rural South India

OBJECTIVES

The emergence and dissemination of carbapenem-resistant Enterobacteriaceae (CRE) is an important public health problem. This study aimed to understand the prevalence and mechanisms of carbapenem resistance in clinically important members of Enterobacteriaceae in rural South India.

METHODS

Routine clinical isolates of Escherichia coli and Klebsiella spp. were tested for Ertapenem (ETP) non-susceptibility by the disk diffusion method over a 3-year period (2012-2014). The ETP non-susceptible isolates were preserved, and tested for the MIC of carbapenems and the carriage of major carbapenemase-encoding genes. Representative genes were sequenced and selective isolates were tested for the production of carbapenemase by carbapenem inactivation method.

RESULTS

A total of 444 ETP non-susceptible isolates were identified in increasing incidence over the study period. Among them, MIC₅₀ and MIC₉₀ of carbapenems (excluding ETP) were 0.25-0.5μg/mL and 8-16μg/mL, respectively, and the prevalence of non-ETP carbapenem resistance was estimated as 3%. Among the 177 tested isolates, 65 (37%) had one or more carbapenemase-encoding genes with a predominance of New Delhi Metallo-β-lactamase (NDM; 32 of 65; 49.2%).

CONCLUSIONS

This study documented the MIC range for carbapenems, prevalence and mechanisms of carbapenem resistance among Enterobacteriaceae in rural South India. It substantiated NDM as a leading mechanism of carbapenem resistance and highlighted the importance of MIC testing in patient management.

Societal willingness to pay to avoid mortality and morbidity from Clostridioides difficile and carbapenem-resistant Enterobacteriaceae infections in the United States

BACKGROUND

Clostridioides difficile infection (CDI) is among the most common health care-associated infections in the United States and is increasingly affecting the elderly. Although carbapenem-resistant Enterobacteriaceae (CRE) infections are still relatively uncommon, there are reported increases in the rate of infection for certain strains, such as Klebsiella pneumoniae. This study examines the burden of mortality and morbidity for CDI and CRE infections in the United States and estimates the societal willingness to pay to avoid them.

METHODS

We use an analytic model to estimate the number of incident cases and associated health outcomes for CDI and CRE infections.

RESULTS

The number of CDI and CRE infection incident cases in the United States in 2016, is estimated at 468,567 and 9,620, respectively. These infections result in a total of 17,630 estimated deaths and 8,624 lost quality-adjusted life years among patients who survive per year.

CONCLUSIONS

Given the significant mortality and morbidity from these infections, the estimated societal willingness to pay to avoid them is high at $176.7 billion per year, of which 93.9% ($166.0 billion) is for CDI. Our estimates far exceed the medical care costs for CDIs and CRE infections reported in the literature despite not capturing the additional costs borne by third-party payers. As incident cases increase or resistant strains develop, the societal willingness to pay is also expected to increase.

Epidemiology of carbapenem-resistant Enterobacteriaceae in a Tertiary Care Center in the Kingdom of Bahrain

PURPOSE

The purpose of the study is to estimate the rate of infection with carbapenem-resistant Enterobacteriaceae (CRE) in the main governmental tertiary care hospital in Bahrain.

MATERIALS AND METHODS

All clinical samples with positive growth of CRE over 6-year period (January 2012-December 2017) were collected from the microbiology laboratory data.

RESULTS

The CRE incidence was high in the first half of study period (2012-2014) and then decreased between 2015 and 2017, after implementation of intensified CRE control measure bundle. About 49.4% of CRE-positive samples were isolated from the elderly age group (above 65 years old), most of them were admitted in the intensive care unit (ICU). The most common isolated organisms were Klebsiella pneumoniae (87.0%), followed by Escherichia coli (7.9%). Isolates from deep tracheal aspirate and midstream urine specimens were the most common source of CRE isolates (27.3%) and (26.3%), respectively. Bacteremia was documented in 21.2% of cases. CRE isolates in the study showed high rates of resistance to aminoglycosides (72.2% resistant to amikacin and 67.3% to gentamicin). Alternatively, most isolates retained their susceptibility to colistin and tigecycline with sensitivity of 83.9% and 85.7%, respectively. Combined resistance to both colistin and tigecycline was observed in 0.06% of total isolates.

CONCLUSION

Elderly population and ICU admission were important risk factors for CRE acquisition. Most of CRE isolates were sensitive to both colistin and tigecycline, which make them the best combination for empiric frontline therapy for suspected serious CRE infection in our facility. Implementing CRE-bundled infection control measures significantly reduced the incidence of CRE infection in our hospital.

Intensive Patient Treatment

Intensive care units (ICUs) are treating hospital’s poorest patients that need medical assistance during the most extreme period of their life. Intensive patients are treated with extensive invasive procedures, which may cause a risk of hospital infections in 10–30% of the cases. More than half of these infections can be prevented. The patients are often admitted directly from outside the hospital or from abroad with trauma after accidents, serious heart and lung conditions, sepsis and other life-threatening diseases. Infection or carrier state of microbes is often unknown on arrival and poses a risk of transmission to other patients, personnel and the environment. Patients that are transferred between different healthcare levels and institutions with unknown infection may be a particular risk for other patients. In spite of the serious state of the patients, many ICUs have few resources and are overcrowded and understaffed, with a lack of competent personnel. ICU should have a large enough area and be designed, furnished and staffed for a good, safe and effective infection control. The following chapter is focused on practical measures to reduce the incidence of infections among ICU patients.

Carbapenem-Resistant Enterobacteriaceae Infections: Taiwan Aspects

Carbapenem-resistant Enterobacteriaceae (CRE), a major resistance concern emerging during the last decade because of significantly compromising the efficacy of carbapenem agents, has currently become an important focus of infection control. Many investigations have shown a high association of CRE infections with high case-fatality rates. In Taiwan, a few surveys observed that a significant proportion (29–47%) of the CR-Klebsiella pneumoniae isolates harbored a plasmidic allele encoding K. pneumoniae carbapenemases (KPC, especially KPC-2). A significant increase in the number of oxacillinase (OXA)-48-like carbapenemases among CR-K. pneumoniae isolates was observed between 2012 and 2015. By striking contrast, isolates of CR-Escherichia coli and CR-Enterobacter species in Taiwan had a much lower percentage of carbapenemase production than CR-K. pneumoniae isolates. This differs from isolates found in China as well as in the India subcontinent. Apart from the hospital setting, CRE was also cultured from the inpatients from communities or long-term care facilities (LTCF). Therefore, implementation of regular CRE screening of LTCF residents, strict disinfectant use in nursing homes and hospital settings, and appropriate control of antibiotic prescriptions is suggested to alleviate the spread of clinical CRE isolates in Taiwan. Although there are some promising new antibiotics against CRE, such as ceftazidime-avibactam, meropenem-vaborbactam, aztreonam-avibactam and cefiderocol, these agents are not available in Taiwan currently. Therefore, in order to effectively decrease case-fatality rates among patients with the infections owing to carbapenemase-producing CRE isolates, combination antibiotic schemes, including colistin (or amikacin) and/or tigecycline in combination with an anti-pseudomonal carbapenem agent, remain the mainstay for treating clinical CRE infections.

Complete Genome Sequence of Klebsiella pneumoniae Siphophage Sugarland

Klebsiella pneumoniae is a Gram-negative bacterium associated with the gastrointestinal tract and is a significant nosocomial pathogen due to its antibiotic resistance. Phage therapy against K. pneumoniae may prove useful in treating infections caused by this bacterium. This announcement describes the genome of the T5-like K. pneumoniae siphophage Sugarland.

Rapid Direct Susceptibility Testing from Positive Blood Cultures by the Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry-Based Direct-on-Target Microdroplet Growth Assay

The recently developed direct-on-target microdroplet growth assay (DOT-MGA) allows rapid universal antimicrobial susceptibility testing (AST) using matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). Here, we investigated a direct application of this method on positive blood cultures (BCs) for the acceleration of sepsis diagnostics. Blood samples spiked with meropenem-nonsusceptible and meropenem-susceptible Enterobacterales isolates were inoculated into Bactec Plus Aerobic/F bottles and incubated in the Bactec automated system. Positive-BC broth was processed using four different methods, filtration/dilution, dilution, lysis/centrifugation, and differential centrifugation. For both dilution-based methods, AST was performed from 1:100, 1:1,000, and 1:10,000 dilutions of positive-BC broth in cation-adjusted Mueller-Hinton broth (CA-MHB). For both centrifugation-based methods, a 0.5 McFarland standard turbidity suspension was prepared from a bacterial pellet and adjusted to a final inoculum of 5 × 10⁵ CFU/ml in CA-MHB. Six-microliter microdroplets with or without meropenem at the breakpoint concentration were spotted in triplicate onto a MALDI-TOF MS target, followed by incubation in a humidity chamber for 3 or 4 h and subsequent broth removal. Spectra were evaluated by MALDI Biotyper software. The test was considered valid if the growth control without antibiotic achieved an identification score of ≥1.7. For samples with meropenem, successful identification (score, ≥1.7) was interpreted as a nonsusceptible result, whereas failed identification (score, <1.7) defined susceptibility. The best test performance was achieved with the lysis/centrifugation method after a 4-h incubation. At this time point, 96.3% validity, 91.7% sensitivity, and 100% specificity were reached. This study demonstrated the feasibility and accuracy of a rapid DOT-MGA from positive BCs. Parallel to susceptibility determination, this method provides simultaneous species identification.

Transmission Surveillance for Antimicrobial-Resistant Organisms in the Health System

Surveillance of antibiotic resistance involves the collection of antibiotic susceptibility patterns undertaken by clinical microbiology laboratories on bacteria isolated from clinical specimens. Global surveillance programs have shown that antibiotic resistance is a major threat to the public at large and play a crucial role in the development of enhanced diagnostics as well as potential vaccines and novel antibiotics with activity against antimicrobial-resistant organisms. This review focuses primarily on examples of global surveillance systems. Local, national, and global integrated surveillance programs with sufficient data linkage between these schemes, accompanied by enhanced genomics and user-friendly bioinformatics systems, promise to overcome some of the stumbling blocks encountered in the understanding, emergence, and transmission of antimicrobial-resistant organisms.

Rapid diagnostics for bloodstream infections: A primer for infection preventionists

Accurate and rapid antimicrobial susceptibility testing with pathogen identification in bloodstream infections is critical to life results for early sepsis intervention. Advancements in rapid diagnostics have shortened the time to results from days to hours and have had positive effects on clinical outcomes and on efforts to combat antimicrobial resistance when paired with robust antimicrobial stewardship programs. This article provides infection preventionists with a working knowledge of available rapid diagnostics for bloodstream infections.

Pharmacokinetics, Safety, and Tolerability of Single and Multiple Doses of Relebactam, a β-Lactamase Inhibitor, in Combination with Imipenem and Cilastatin in Healthy Participants

Relebactam is a novel class A and C β-lactamase inhibitor that is being developed in combination with imipenem-cilastatin for the treatment of serious infections with Gram-negative bacteria. Here we report on two phase 1 randomized, double-blind, placebo-controlled pharmacokinetics, safety, and tolerability studies of relebactam administered with or without imipenem-cilastatin to healthy participants: (i) a single-dose (25 to 1,150 mg) and multiple-dose (50 to 625 mg every 6 h [q6h] for 7 to 14 days) escalation study with men and (ii) a single-dose (125 mg) study with women and elderly individuals.

Relebactam is a novel class A and C β-lactamase inhibitor that is being developed in combination with imipenem-cilastatin for the treatment of serious infections with Gram-negative bacteria. Here we report on two phase 1 randomized, double-blind, placebo-controlled pharmacokinetics, safety, and tolerability studies of relebactam administered with or without imipenem-cilastatin to healthy participants: (i) a single-dose (25 to 1,150 mg) and multiple-dose (50 to 625 mg every 6 h [q6h] for 7 to 14 days) escalation study with men and (ii) a single-dose (125 mg) study with women and elderly individuals. Following single- or multiple-dose intravenous administration over 30 min, plasma relebactam concentrations declined biexponentially, with a terminal half-life (t_1/2) ranging from 1.35 to 1.85 h independently of the dose. Exposures increased in a dose-proportional manner across the dose range. No clinically significant differences in pharmacokinetics between men and women, or between adult and elderly participants, were observed. Urine pharmacokinetics demonstrated that urinary excretion is the major route of relebactam elimination. No drug-drug interaction between relebactam and imipenem-cilastatin was observed, and the observed t_1/2 values for relebactam, imipenem, and cilastatin were comparable, thus supporting coadministration. Relebactam administered alone or in combination with imipenem-cilastatin was well tolerated across the dose ranges studied. No serious adverse events or deaths were reported. The pharmacokinetic profile and favorable safety results supported q6h dosing of relebactam with imipenem-cilastatin in clinical treatment trials.