Impact of vanA-Positive Enterococcus faecium Exhibiting Diverse Susceptibility Phenotypes to Glycopeptides on 30-Day Mortality of Patients with a Bloodstream Infection

Microbiological profiles and clinical outcomes of critically ill surgical patients with lower gastrointestinal perforation in Japan: a single-center retrospective observational study

BACKGROUND

Lower gastrointestinal perforation (LGP) is a surgical emergency disease that can result in secondary bacterial peritonitis. Microbiological studies on LGP are rare. The present study aimed to ascertain the microbiological profile of LGP in patients admitted to the intensive care unit (ICU) at our institute after surgery. In addition, we investigated whether initial empirical therapy with vancomycin was associated with in-hospital mortality, duration of ICU stay, and duration of ventilator support.

METHODS

This single-center, retrospective, observational study was conducted at Kobe City Medical Center General Hospital, Japan. The study population included all patients diagnosed with LGP who were admitted to the ICU after emergency surgery between 2017 and 2023. The primary outcome assessed was the microbiological profile of microorganisms isolated from ascites fluid and blood of the participants. The secondary end-points were in-hospital mortality, duration of ICU stay, and duration of ventilator support. We performed univariate and multivariate regression analyses to evaluate the end-points.

RESULTS

During the study period, 89 patients were included in the analysis. The most commonly identified pathogen from the ascites cultures was Escherichia coli (65.2%), followed by Enterococcus spp. (51.7%). E. faecium was identified in 16 (18.0%) ascites samples. The microbiological profile of critically ill patients with LGP admitted to the ICU after surgery was similar to that of previous studies on intra-abdominal infection (IAI). Therefore, the initial empirical therapy in the IAI guidelines is more appropriate for LGP. Multivariate regression analysis suggested that the combination of initial empirical therapy with vancomycin was not associated with in-hospital mortality (odds ratio [OR] = 0.96, 95% confidence interval [CI] 0.23-3.00, p = 0.955), duration of ICU stay (coefficient=-0.92, 95% CI -3.04-1.21, p = 0.393), or duration of ventilator-support (coefficient=-9.03, 95%CI -49.69-31.63, p = 0.659).

CONCLUSION

The microbiological profile of critically ill patients with LGP admitted to the ICU after surgery was similar to that of previous studies on IAI. However, the frequency of E. faecium in the present study was higher than that in previous studies. Initial empirical therapy with drugs such as meropenem in combination with vancomycin for E. faecium was not associated with in-hospital mortality, duration of ICU stay, and duration of ventilator support, after adjusting for confounding factors.

Characteristics and Prevalence of Vancomycin-variable Enterococcus faecium bacteremia in southern Taiwan

BACKGROUND

Vancomycin-variable enterococci (VVE) are vanA-carrying Enterococcus faecium that are phenotypically susceptible to vancomycin and can only be detected using molecular methods, leading to the possibility of treatment failure and posing threats to infection control. This study aimed to determine the prevalence of VVE and its associated clinical risk factors.

METHODS

This retrospective study was conducted in two hospitals in southern Taiwan. Patients with phenotypically vancomycin-susceptible E. faecium bacteremia were enrolled between 2017 and 2021. VVEs were defined as isolates harboring the vanA gene that were phenotypically susceptible to vancomycin. Vancomycin-susceptible E. faecium (VSE) isolates were phenotypically susceptible to vancomycin and lacked vanA or vanB genes.

RESULTS

Of the 142 enrolled patients, 121 (85.2%) had VSE and 21 (14.8%) had VVE. Resistance rates to penicillin, tetracycline, and fosfomycin were higher in VVE isolates. Malignancy (adjusted odds ratio [aOR] = 4.87; 95% confidence interval [CI] 1.54-15.41, p = 0.007) and central venous catheter usage (aOR = 4.69; 95% CI 1.49-14.78, p = 0.008) were the independent risk factors associated with VVE bacteremia. Being male (aOR = 0.12, CI 0.03-0.44, p = 0.002) was less likely to be associated with VVE bacteremia. Although VVE was not associated with 30-day mortality (38.1% [VVE] vs. 35.5% [VSE], p = 0.822), one case of subsequent vancomycin-resistant enterococci infection in the VVE group with vancomycin treatment (4.8%, 1/21) was identified, which led to subsequent mortality.

CONCLUSIONS

The prevalence of VVE was high among E. faecium isolates with vancomycin-susceptible phenotypes in southern Taiwan. Although the current study revealed that VVE bacteremia was not associated with poor clinical outcome, further multicenter surveillance survey is recommended to evaluate the possible impact of VVE on public health in Taiwan.

A systematic review on the excess health risk of antibiotic-resistant bloodstream infections for six key pathogens in Europe

BACKGROUND

Antimicrobial resistance is a global threat, which requires novel intervention strategies, for which priority pathogens and settings need to be determined.

OBJECTIVES

We evaluated pathogen-specific excess health burden of drug-resistant bloodstream infections (BSIs) in Europe.

METHODS

A systematic review and meta-analysis.

DATA SOURCES

MEDLINE, Embase, and grey literature for the period January 1990 to May 2022.

STUDY ELIGIBILITY CRITERIA

Studies that reported burden data for six key drug-resistant pathogens: carbapenem-resistant (CR) Pseudomonas aeruginosa and Acinetobacter baumannii, third-generation cephalosporin or CR Escherichia coli and Klebsiella pneumoniae, methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus faecium. Excess health outcomes compared with drug-susceptible BSIs or uninfected patients. For MRSA and third-generation cephalosporin E. coli and K. pneumoniae BSIs, five or more European studies were identified. For all others, the search was extended to high-income countries.

PARTICIPANTS

Paediatric and adult patients diagnosed with drug-resistant BSI.

INTERVENTIONS

Not applicable.

ASSESSMENT OF RISK OF BIAS

An adapted version of the Joanna-Briggs Institute assessment tool.

METHODS OF DATA SYNTHESIS

Random-effect models were used to pool pathogen-specific burden estimates.

RESULTS

We screened 7154 titles, 1078 full-texts and found 56 studies on BSIs. Most studies compared outcomes of drug-resistant to drug-susceptible BSIs (46/56, 82.1%), and reported mortality (55/56 studies, 98.6%). The pooled crude estimate for excess all-cause mortality of drug-resistant versus drug-susceptible BSIs ranged from OR 1.31 (95% CI 1.03-1.68) for CR P. aeruginosa to OR 3.44 (95% CI 1.62-7.32) for CR K. pneumoniae. Pooled crude estimates comparing mortality to uninfected patients were available for vancomycin-resistant Enterococcus and MRSA BSIs (OR of 11.19 [95% CI 6.92-18.09] and OR 6.18 [95% CI 2.10-18.17], respectively).

CONCLUSIONS

Drug-resistant BSIs are associated with increased mortality, with the magnitude of the effect influenced by pathogen type and comparator. Future research should address crucial knowledge gaps in pathogen- and infection-specific burdens to guide development of novel interventions.

Epidemiology and outcomes of vancomycin-resistant enterococcus infections: a systematic review and meta-analysis

Vancomycin-resistant enterococci (VRE) cause many infections in the healthcare context. Knowledge regarding the epidemiology and burden of VRE infections, however, remains fragmented. We aimed to summarize recent studies on VRE epidemiology and outcomes in hospitals, long-term-care facilities (LTCFs) and nursing homes worldwide based on current epidemiological reports. We searched MEDLINE/PubMed, the Cochrane Library, and Web of Science for observational studies, which reported on VRE faecium and faecalis infections in in-patients published between January 2014 and December 2020. Outcomes were incidence, infection rate, mortality, length of stay (LOS), and healthcare costs. We conducted a meta-analysis on mortality (PROSPERO registration number: CRD42020146389). Of 681 identified publications, 57 studies were included in the analysis. Overall quality of evidence was moderate to low. VRE incidence was rarely and heterogeneously reported. VRE infection rate differed highly (1-55%). The meta-analysis showed a higher mortality for VRE faecium bloodstream infections (BSIs) compared with VSE faecium BSIs (risk ratio, RR 1.46; 95% confidence interval (CI) 1.17-1.82). No difference was observed when comparing VRE faecium vs VRE faecalis BSI (RR 1.00, 95% CI 0.52-1.93). LOS was higher in BSIs caused by E. faecium vs E. faecalis. Only three studies reported healthcare costs. In contrast to previous findings, our meta-analysis of included studies indicates that vancomycin resistance independent of VRE species may be associated with a higher mortality. We identified a lack of standardization in reporting outcomes, information regarding healthcare costs, and state-of-the-art microbiological species identification methodology, which may inform the set-up and reporting of future studies.

Major Bloodstream Infection-Causing Bacterial Pathogens and Their Antimicrobial Resistance in South Korea, 2017-2019: Phase I Report From Kor-GLASS

To monitor national antimicrobial resistance (AMR), the Korea Global AMR Surveillance System (Kor-GLASS) was established. This study analyzed bloodstream infection (BSI) cases from Kor-GLASS phase I from January 2017 to December 2019. Nine non-duplicated Kor-GLASS target pathogens, including Staphylococcus aureus, Enterococcus faecalis, Enterococcus faecium, Streptococcus pneumoniae, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Acinetobacter spp., and Salmonella spp., were isolated from blood specimens from eight sentinel hospitals. Antimicrobial susceptibility testing, AMR genotyping, and strain typing were carried out. Among the 20,041 BSI cases, 15,171 cases were caused by one of the target pathogens, and 12,578 blood isolates were collected for the study. Half (1,059/2,134) of S. aureus isolates were resistant to cefoxitin, and 38.1% (333/873) of E. faecium isolates were resistant to vancomycin. Beta-lactamase-non-producing ampicillin-resistant and penicillin-resistant E. faecalis isolates by disk diffusion method were identified, but the isolates were confirmed as ampicillin-susceptible by broth microdilution method. Among E. coli, an increasing number of isolates carried the bla _CTX-M-27 gene, and the ertapenem resistance in 1.4% (30/2,110) of K. pneumoniae isolates was mostly (23/30) conferred by K. pneumoniae carbapenemases. A quarter (108/488) of P. aeruginosa isolates were resistant to meropenem, and 30.5% (33/108) of those carried acquired carbapenemase genes. Over 90% (542/599) of A. baumannii isolates were imipenem-resistant, and all except one harbored the bla _OXA-23 gene. Kor-GLASS provided comprehensive AMR surveillance data, and the defined molecular mechanisms of resistance helped us to better understand AMR epidemiology. Comparative analysis with other GLASS-enrolled countries is possible owing to the harmonized system provided by GLASS.

Genetic description of VanD phenotype vanA genotype in vancomycin-resistant Enterococcus faecium isolates from a Bone Marrow Transplantation Unit

BACKGROUND

Vancomycin-resistant Enterococcus faecium (VREfm) is an important agent of hospital-acquired infection. VanA phenotype is characterized by resistance to high levels of vancomycin and teicoplanin and is encoded by the vanA gene, whereas VanD phenotype is characterized by resistance to vancomycin and susceptibility or intermediate resistance to teicoplanin; however, some isolates carry a VanD phenotype with a vanA genotype, but there are many gaps in the knowledge about the genetic mechanisms behind this pattern.

OBJECTIVE

To characterize the genetic structure, clonality, and mobile genetic elements of VRE isolates that display a VanD-vanA phenotype.

RESULTS

All vanA VRE-fm isolates displayed minimum inhibitory concentration (MIC) for vancomycin > 32µg/mL and intermediate or susceptible MIC range for teicoplanin (8-16µg/mL). The isolates were not clonal, and whole-genome sequencing analysis showed that they belonged to five different STs (ST478, ST412, ST792, ST896, and ST1393). The absence of some van complex genes were observed in three isolates: Ef5 lacked vanY and vanZ, Ef2 lacked vanY, and Ef9 lacked orf1 and orf2; moreover, another three isolates had inverted positions of orf1, orf2, vanR, and vanS genes. IS1542 was observed in all isolates, whereas IS1216 in only five. Moreover, presence of other hypothetical protein-encoding genes located downstream the vanZ gene were observed in six isolates.

CONCLUSION

VRE isolates can display some phenotypes associated to vanA genotype, including VanA and VanB, as well as VanD; however, further studies are needed to understand the exact role of genetic variability, rearrangement of the transposon Tn1546, and presence of insertion elements in isolates with this profile.