Epidemiology of and risk factors for mortality due to carbapenemase-producing organisms (CPO) in healthcare facilities

Genomic investigation of multispecies and multivariant blaNDM outbreak reveals key role of horizontal plasmid transmission

OBJECTIVES

New Delhi metallo-β-lactamases (NDMs) are major contributors to the spread of carbapenem resistance globally. In Australia, NDMs were previously associated with international travel, but from 2019 we noted increasing incidence of NDM-positive clinical isolates. We investigated the clinical and genomic epidemiology of NDM carriage at a tertiary-care Australian hospital from 2016 to 2021.

METHODS

We identified 49 patients with 84 NDM-carrying isolates in an institutional database, and we collected clinical data from electronic medical record. Short- and long-read whole genome sequencing was performed on all isolates. Completed genome assemblies were used to assess the genetic setting of blaNDM genes and to compare NDM plasmids.

RESULTS

Of 49 patients, 38 (78%) were identified in 2019-2021 and only 11 (29%) of 38 reported prior travel, compared with 9 (82%) of 11 in 2016-2018 (P = .037). In patients with NDM infection, the crude 7-day mortality rate was 0% and the 30-day mortality rate was 14% (2 of 14 patients). NDMs were noted in 41 bacterial strains (ie, species and sequence type combinations). Across 13 plasmid groups, 4 NDM variants were detected: blaNDM-1, blaNDM-4, blaNDM-5, and blaNDM-7. We noted a change from a diverse NDM plasmid repertoire in 2016-2018 to the emergence of conserved blaNDM-1 IncN and blaNDM-7 IncX3 epidemic plasmids, with interstrain spread in 2019-2021. These plasmids were noted in 19 (50%) of 38 patients and 35 (51%) of 68 genomes in 2019-2021.

CONCLUSIONS

Increased NDM case numbers were due to local circulation of 2 epidemic plasmids with extensive interstrain transfer. Our findings underscore the challenges of outbreak detection when horizontal transmission of plasmids is the primary mode of spread.

Metallo-beta-lactamases: mechanisms, treatment challenges, and future prospects

INTRODUCTION

Metallo-beta-lactamases (MBLs) are responsible for resistance to almost all beta-lactam antibiotics. Found predominantly in Gram-negative bacteria, they severely limit treatment options. Understanding the epidemiology, risk factors, treatment, and prevention of infections caused by MBL-producing organisms is essential to reduce their burden.

AREAS COVERED

The origins and structure of MBLs are discussed. We describe the mechanisms of action that differentiate MBLs from other beta-lactamases. We discuss the global epidemiology of MBL-producing organisms and their impact on patients' outcomes. By exposing the mechanisms of transmission of MBLs among bacterial populations, we emphasize the importance of infection prevention and control.

EXPERT OPINION

MBLs are spreading globally and challenging the majority of available antibacterial agents. Genotypic tests play an important role in the identification of MBL production. Phenotypic tests are less specific but may be used in low-resource settings, where MBLs are more predominant. Infection prevention and control are critical to reduce the spread of organisms producing MBL in healthcare systems. New combinations such as avibactam-aztreonam and new agents such as cefiderocol have shown promising results for the treatment of infections caused by MBL-producing organisms. New antibiotic and non-antibiotic agents are being developed and may improve the management of infections caused by MBL-producing organisms.

Incidence, antimicrobial resistance and mortality of Pseudomonas aeruginosa bloodstream infections among hospitalized patients in China: a retrospective observational multicenter cohort study from 2017 to 2021

Background

Pseudomonas aeruginosa (P. aeruginosa) accounts for high antimicrobial resistance and mortality rates of bloodstream infections (BSIs). We aim to investigate incidence, antimicrobial resistance and risk factors for mortality of P. aeruginosa BSIs among inpatients.

Methods

A retrospective cohort study were conducted at two tertiary hospitals in 2017-2021. Medical and laboratory records of all inpatients diagnosed with P. aeruginosa BSIs were reviewed. A generalized linear mixed model was used to identify risk factors for mortality.

Results

A total of 285 patients with P. aeruginosa BSIs were identified. Incidence of P. aeruginosa BSIs fluctuated between 2.37 and 3.51 per 100,000 patient-days over the study period. Out of 285 P. aeruginosa isolates, 97 (34.04%) were carbapenem-resistant (CR) and 75 (26.32%) were multidrug-resistant (MDR). These isolates showed low resistance to aminoglycosides (9.51-11.62%), broad-spectrum cephalosporins (17.19-17.61%), fluoroquinolones (17.25-19.43%), and polymyxin B (1.69%). The crude 30-day mortality rate was 17.89% (51/285). Healthcare costs of patients with MDR/CR isolates were significantly higher than those of patients with non-MDR/CR isolates (P < 0.001/=0.002). Inappropriate definitive therapy [adjusted odds ratio (aOR) 4.47, 95% confidence interval (95% CI) 1.35-14.77; P = 0.014], ICU stay (aOR 2.89, 95% CI: 1.26-6.63; P = 0.012) and corticosteroids use (aOR 2.89, 95% CI: 1.31-6.41; P = 0.009) were independently associated with 30-day mortality.

Conclusion

Incidence of P. aeruginosa BSIs showed an upward trend during 2017-2020 but dropped in 2021. MDR/CR P. aeruginosa BSIs are associated with higher healthcare costs. Awareness is required that patients with inappropriate definitive antimicrobial therapy, ICU stay and corticosteroids use are at higher risk of death from P. aeruginosa BSIs.

Predictors of Mortality in Patients with Infections Due to Carbapenem-Resistant Gram-Negative Bacteria

INTRODUCTION

Infections caused by carbapenem-resistant Gram-negative bacteria (CR-GNB) are a significant cause of mortality and represent a serious challenge to health systems. The early identification of mortality predictors could guide appropriate treatment and follow-up. We aimed to identify the factors associated with 90-day all-cause mortality in patients with CR-GNB infections.

METHODS

We conducted a cohort study from 1 January 2019 to 30 April 2022. The primary outcome was death from any cause during the first 90 days after the date of the first CR-GNB-positive culture. Secondary outcomes included infection relapse, invasive mechanical ventilation during follow-up, need for additional source control, acute kidney injury, Clostridioides difficile infection, and all-cause hospital admission after initial discharge. Bivariate and multivariate Cox-proportional hazards models were constructed to identify the factors independently associated with 90-day all-cause mortality.

RESULTS

A total of 225 patients with CR-GNB infections were included. Death occurred in 76 (34%) cases. The most-reported comorbidities were immunosuppression (43%), arterial hypertension (35%), and COVID-19 (25%). The median length of stay in survivors was 18 days (IQR 10-34). Mechanical ventilation and ICU admission after diagnosis occurred in 8% and 11% of cases, respectively. Both infection relapse and rehospitalisation occurred in 18% of cases. C. difficile infection was diagnosed in 4% of cases. Acute kidney injury was documented in 22% of patients. Mechanical ventilation after diagnosis, ICU admission after diagnosis, and acute kidney injury in the first ten days of appropriate treatment were more frequently reported among non-survivors. In the multivariate analysis, age (HR 1.19 (95%CI 1.00-1.83)), immunosuppression (HR 1.84 (95%CI 1.06-3.18)), and septic shock at diagnosis (HR 2.40 (95% 1.41-4.08)) had an independent association with death during the first 90 days after the CR-GNB infection diagnosis. Receiving antibiogram-guided appropriate treatment was independently associated with a lower risk of death (HR 0.25 (95%CI 0.14-0.46)).

CONCLUSIONS

The presence of advanced age, immunosuppression, septic shock at diagnosis, and inappropriate treatment are associated with higher 90-day all-cause mortality in hospitalised patients with infections due to CR-GNB. Recognition of the risk factors for adverse outcomes could further assist in patient care and the design of interventional studies that address the severe and widespread problem that is carbapenem resistance.

Healthcare-associated infections and antimicrobial resistance in Canadian acute care hospitals, 2017-2021

Background

Healthcare-associated infections (HAIs) and antimicrobial resistance (AMR) continue to contribute to excess morbidity and mortality among Canadians. This report describes epidemiologic and laboratory characteristics and trends of HAIs and AMR from 2017 to 2021 (Candida auris 2012-2021) using surveillance and laboratory data submitted by hospitals to the Canadian Nosocomial Infection Surveillance Program (CNISP) and by provincial laboratories to the National Microbiology Laboratory (NML).

Methods

Data collected from 88 Canadian sentinel acute care hospitals between January 1, 2017, and December 31, 2021, for Clostridioides difficile infections (CDI), carbapenemase-producing Enterobacterales (CPE), methicillin-resistant Staphylococcus aureus (MRSA) bloodstream infections (BSIs) and vancomycin-resistant Enterococcus (VRE) BSIs. Candida auris (C. auris) surveillance was initiated in 2019 by CNISP and in 2012 by the NML. Case counts, rates, outcomes, molecular characterization and antimicrobial resistance profiles are presented.

Results

From 2017 to 2021, increased rates per 10,000 patient days were observed for MRSA BSIs (35%; 0.84-1.13), VRE BSIs (43%; 0.23-0.33) and CPE infections (166%, 0.03-0.08). CDI rates decreased 11% (5.68-5.05). Thirty-one C. auris isolates were identified in Canada from 2012 to 2021, with the majority from Western Canada (68%).

Conclusion

From 2017 to 2021, the incidence of MRSA and VRE BSIs, and CPE infections increased in Canadian acute care hospitals participating in a national sentinel network (CNISP) while CDI decreased. Few C. auris isolates were identified from 2012 to 2021. Reporting standardized surveillance data and the consistent application of infection prevention and control practises in acute care hospitals are critical to help decrease the burden of HAIs and AMR in Canada.

Risk factors in non‑surviving patients with infection with carbapenemase‑producing Enterobacterales strains in an intensive care unit

Carbapenemase-producing Enterobacterales (CPE) are Gram-negative bacteria that belong to the Enterobacterales family and produce enzymes known as carbapenemases, which inhibit carbapenems, cephalosporins and penicillins. Carbapenem-resistant Enterobacterales (CRE) are resistant to carbapenems, cephalosporins and penicillins via mechanisms that may or may not produce carbapenemases. The identification of carbapenems is critical for the initiation of proper antibiotic therapy. The present case-control, retrospective study included 64 patients with CPE strains admitted to an intensive care unit between September, 2017 and October, 2021; of these, 34 patients with CPE succumbed and 30 control patients with CPE strains survived. CPE strains in the deceased patients were caused by Klebsiella spp. in 31 cases (91.2%) and Escherichia coli in 3 cases (8.8%). The univariate analysis revealed that the predictive factors associated with mortality in patients with CPE were admission with coronavirus disease 2019 (COVID-19) (P=0.001), invasive mechanical ventilation (P=0.001), and treatment with corticosteroids (P=0.006). The multivariate analysis revealed that admission with COVID-19 [odds ratio (OR), 16.26; 95% confidence interval (CI), 3.56-74.14; P≤0.05] and invasive mechanical ventilation (OR, 14.98; 95% CI, 1.35-166.22; P≤0.05) were associated with mortality as independent risk factors. Admission with COVID-19 increased the risk of mortality 16.26-fold and invasive mechanical ventilation increased the risk of mortality by 14.98-fold. On the whole, the present study demonstrates that the length of hospital duration in patients who acquired CPE did not influence mortality, whereas infection with COVID-19 increased and invasive mechanical ventilation were associated with an increased risk of mortality.

In vitro activity of aztreonam/avibactam against isolates of Enterobacterales collected globally from ATLAS in 2019

OBJECTIVES

Infections caused by drug-resistant Enterobacterales including those producing metallo-β-lactamases (MBLs) are particularly challenging due to limited therapeutic options. The drug combination aztreonam/avibactam (ATM-AVI) is under clinical development for treating serious infections caused by these strains. This study assessed the in vitro activity of ATM-AVI against Enterobacterales isolates collected globally in the ATLAS surveillance programme in 2019.

METHODS

Clinical isolates of Enterobacterales (N=18713) including Citrobacter freundii, Citrobacter koseri, Enterobacter cloacae complex, Escherichia coli, Klebsiella aerogenes, Klebsiella oxytoca, Klebsiella pneumoniae, Proteus mirabilis, and Serratia marcescens collected from 232 sites in 2019 were analysed. Antimicrobial susceptibility testing was performed by reference broth microdilution. A pharmacokinetic/pharmacodynamic based breakpoint of 8 mg/L was considered for ATM-AVI activity.

RESULTS

ATM-AVI demonstrated potent antimicrobial activity against all Enterobacterales, with 99.9% isolates inhibited at MIC ≤8 mg/L (MIC₉₀, 0.25 mg/L). MICs ≤8 mg/L (>99.0%) were noted for ATM-AVI across regions worldwide. Among other antimicrobials, amikacin, colistin, imipenem, meropenem, and tigecycline were also active (susceptibility >85.0%) against Enterobacterales. Activity of ATM-AVI was sustained against multi-drug resistant, extended-spectrum β-lactamases producing, and carbapenem-resistant isolates (susceptibility >99%; MIC₉₀, 0.25-0.5 mg/L). Importantly, potent activity for ATM-AVI (>99.0%; MIC_90, 0.5 mg/L) was noted among MBL-positive isolates and those producing other carbapenemases, such as KPC and OXA-48.

CONCLUSIONS

Our results demonstrated that ATM-AVI was highly active against a recent collection of Enterobacterales isolates, including those producing MBLs either alone or in combination with other carbapenemases. Thus, ATM-AVI represents a potential option for treating infections caused by antibiotic-resistant Enterobacterales including MBL-producing strains.

Temocillin: Applications in Antimicrobial Stewardship as a Potential Carbapenem-Sparing Antibiotic

Temocillin is an old antibiotic, but given its particular characteristics, it may be a suitable alternative to carbapenems for treating infections due to ESBL-producing Enterobacterales and uncomplicated UTI due to KPC-producers. In this narrative review, the main research question was to summarize current evidence on temocillin and its uses in infectious diseases. A search was run on PubMed using the terms (‘Temocillin’ [Mesh]) AND (‘Infection’ [Mesh]). Current knowledge regarding temocillin in urinary tract infection, blood-stream infections, pneumonia, intra-abdominal infections, central nervous system infections, skin and soft tissues infections, surgical sites infections and osteoarticular Infections were summarized. Temocillin retain a favourable profile on microbiota and risk of Clostridioides difficile infections and could be an option for treating outpatients. Temocillin may be a valuable tool to treat susceptible pathogens and for which a carbapenem could be spared. Other advantages in temocillin use are that it is well-tolerated; it is associated with a low rate of C. difficile infections; it is active against ESBL, AmpC, and KPC-producing Enterobacterales; and it can be used in the OPAT clinical setting.