Enterococcal Isolates Research Articles

P-186. Trends in Antimicrobial Resistance Among Adults Across 6 Hospitals in Argentina, Brazil, and Chile, 2018-2022

Abstract Background In 2019, an estimated 1.27 million deaths were attributed to bacterial antimicrobial resistance (AR) globally. During the Coronavirus Disease 2019 (COVID-19) Pandemic, additional strain was placed on healthcare systems that may have led to further increases in AR. We evaluated AR prevalence before and after the onset of COVID-19 in 6 healthcare facilities (HCF) in South America. Methods We conducted an ecological evaluation of HCF-wide AR prevalence in 4 private and 2 public HCFs in Argentina, Brazil, and Chile; 2 HCFs per country. We calculated percentage of non-susceptible (NS) or resistant (R) to select antibiotics among clinical isolates of Acinetobacter baumannii, Pseudomonas aeruginosa, Enterococcus spp., and Enterobacterales cultured from adult acute care inpatients. We compared percentage-NS or -R between the periods pre- (March 2018–February 2020) and post- (March 2020–February 2022) onset of the COVID-19 pandemic. Chi-square or Fisher’s exact tests were used with statistical significance set at a two-tailed p< 0.05. Results When comparing 2020-2022 to 2018-2020, 2/6 hospitals showed statistically significant increases (+14.1–19.2%) in carbapenem-NS A. baumannii. For carbapenem-NS P. aeruginosa, 1/6 hospitals showed a significant increase (+76.6%) and 1/6 showed a significant decrease (-52.4%). For carbapenem-NS Enterobacterales, 2/6 hospitals had significant increases (+50.7–236.2%) and 1 exhibited a significant decrease (-91.7%). For vancomycin-R Enterococcus spp., 2/6 hospitals had significant increases (+43.9–400.0%) and 2/6 hospitals had significant decreases (-49.0-60.7%). For Enterobacterales-R to 3rd generation cephalosporins, 2/6 hospitals showed significant increases (+16.0–110.9%) and 1/6 hospitals had a significant decrease (-40.4%) (Table). Conclusion Among the isolates from our study hospitals, we noted not only significant increases but also significant decreases across multiple AR profiles associated with multi-drug resistance. These data suggest that the pandemic may have led to changes in resistance among both gram-negative and gram-positive bacteria. Given the variability in these changes, further evaluation of infection rates would be valuable to confirm these findings. Disclosures José M Munita, MD, MSD: Grant/Research Support|Pfizer: Grant/Research Support

P-870. Daptomycin-Susceptible vs. Daptomycin-Non-susceptible Enterococcus Bloodstream Infections: Rates and Predictors of Treatment Failure and Predictors of Daptomycin Resistance

Abstract Background Daptomycin is a well-tolerated option to treat resistant enterococci; however, updated breakpoints from the Clinical Laboratory and Standards Institute (CLSI) have led to increasing numbers of ‘susceptible, dose-dependent’ (SDD) or daptomycin non-susceptible (DNS) isolates. Methods This study was to determine if isolation of daptomycin-sensitive enterococcal (DSE) or daptomycin-non-susceptible enterococcal (DNSE) isolates from the blood impacts patient outcomes. A retrospective, observational, cohort of patients within the Veteran’s Affairs (VA) Healthcare System from 1 January 2017 to 31 December 2021 with at least 1 blood culture positive for Enterococcus faecalis or E. faecium was identified. Patients were analyzed in 3 cohorts: 1) all included patients, 2) only patients with minimum inhibitory concentration (MIC) data available, and 3) E. faecium isolates and DSE isolates only. The primary outcome of treatment failure was a composite of 30-day mortality and microbiological failure. Two multivariate regressions were conducted - one to establish predictors of treatment failure and one to establish predictors for daptomycin non-susceptibility. Results Two hundred four patients were included (90 DSE, 114 DNSE). In cohort 1, 63.3% (57) DSE patients experienced failure vs. 58.8% (67) in the DNSE group (p = 0.56). Sixty-nine percent (40/58) of DSE patients failed in cohort 2 vs. 56.4% (35/62) of DNSE patients (p = 0.157), and 69% (40/58) of DSE and 64.4% (56/87) of DNSE failed in cohort 3 (p = 0.56). Multivariate regression revealed infectious diseases (ID) consultation (OR 0.402; 95% CI, 0.176-0.918; p = 0.030) was associated with reduced risk of failure, while infection with vancomycin-resistant enterococcus (OR 2.04; 95% CI 1.028-4.049; p = 0.04) and endocarditis/endovascular source of infection (OR 4.33; 95% CI 1.34 – 13.99; p = 0.01) were associated with increased risk of failure. Previous beta-lactam and vancomycin exposure were associated with increased risk of DNSE. Conclusion No significant difference in failure between patients with DSE and DNSE bacteremias was observed; however, ID consultation was found to be protective, and previous antibiotic exposure was associated with increased DNSE risk. Disclosures All Authors: No reported disclosures

P-1464. Clinical Outcomes of patients with Infection Secondary to VancomycinResistant Enterococci (VRE)

Abstract Background Daptomycin dose dependent VRE infection is a growing clinical challenge to patients and healthcare providers. In this study, we sought to describe patients with infections secondary to Daptomycin-susceptible and dose-dependent VRE. Methods We conducted a retrospective cohort study of adult patients admitted at Ochsner LSU Health Shreveport- Academic Medical Center who were diagnosed with VRE infections between 2019 and 2024. We evaluated risk factors, comorbidities, treatment regimens and clinical outcomes of VRE infections with daptomycin MIC 4 mcg/ml (group 1) vs those with VRE daptomycin MIC < 4 mcg/ml (group 2). Results Out of 85 patients with different VRE infections, 42 (49.41%) had a daptomycin MIC = 4, while 41 (48.23%) had a daptomycin MIC < 4. Different sources of VRE infections were identified among the two groups. Polymicrobial infection rates were 54.76% in group 1 and 60.97% in group 2. History of previous infection with vancomycin-sensitive Enterococcus was observed in 12% of group 1 and 17% of group 2. The majority of Enterococcus isolates were E. faecium: 97.6% in group 1 and 58.5% in group 2. Comparable factors between the two groups included the presence of external lines, coexisting chronic kidney disease (CKD), and previous beta-lactam use. The targeted antibiotics included daptomycin only, linezolid only, or a combination of either one with ceftaroline or a beta-lactam. The duration of daptomycin treatment was 23.86 days in group 1 and 21.8 days in group 2. In group 1, 80.95% received a daptomycin dose higher than the standard dose of 6 mg/kg, compared to 46.34% in group 2. A dose of 10 mg/kg was significantly observed in 33.3% of group 1 and 9.8% of group 2. The 30-day mortality rate in group 1 (MIC = 4) was 11.90%, whereas in group 2 (MIC < 4), it was 14.63%. Conclusion Our data revealed a higher incidence of VRE infections with a MIC = 4 mcg/ml among Enterococcus faecium species. Additionally, VRE infections with a higher MIC = 4 were associated with comorbidities such as chronic kidney disease and the presence of external devices and central venous catheters. Understanding these risk factors can aid in identifying high-risk patient populations and implementing targeted preventive measures. Disclosures All Authors: No reported disclosures

Positive Intraoperative Bile Culture and Antibiotic Resistance Increase the Risk of Pancreatic Fistula in Patients After Pancreatoduodenectomy.

Background/Objectives: A positive intraoperative bile culture (bacterobilia) is considered to be a risk factor for increased morbidity after pancreatoduodenectomy. The aim of our study was to describe the frequency of bacterobilia with a special emphasis on antibiotic resistance and to analyze the association of these findings with postoperative complications, in particular with postoperative pancreatic fistula. Methods: From a prospective database, patients with available intraoperative bile cultures (n = 95) were selected and analyzed. Microbiological test results reported the type of bacteria as well as sensitivity and resistance patterns. Associations between culture results, antibiotic resistance, and postoperative outcomes were assessed. Results: Among 95 patients that were included in this trial, 71 (74.7%) had a positive bile culture. A total of 29.6% (21/71) of patients with positive bile cultures developed POPF grade B/C compared to 8.3% (2/24) of patients with negative bile cultures (p = 0.052). The difference in CR-POPF became statistically significant when at least one of the isolated microorganisms was resistant to ampicillin/sulbactam, the perioperative antibiotic administered for prophylaxis. CR-POPF was diagnosed in 38.5% (15/39) of patients with antibiotic resistance vs. 14.3% (8/56) of patients without resistant microorganisms (p = 0.007). We also identified the isolation of Enterococcus spp. (p = 0.006), resistant Enterobacter (p = 0.031), or resistant Escherichia coli (p = 0.027) as risk factors for pancreatic fistula. Conclusions: The isolation of antibiotic-resistant strains in a positive bile culture is a major risk factor for the development of pancreatic fistula after pancreatoduodenectomy. The most relevant bacteria in our study were Enterococcus spp., Enterobacter cloacae, and Escherichia coli. Thus, broad-spectrum antimicrobial prophylaxis with efficacy against these microorganisms and with low resistance rates should be routinely administered perioperatively.

Potential of Pine Biochar to Mitigate Bacterial Hazards Present in Recycled Manure Solids from Dairy Cows.

The use of recycled manure solids (RMS) as cow bedding in dairy farms poses concerns due to its potential to harbor pathogenic and antimicrobial-resistant bacteria. This study evaluated the impact of RMS supplementation with biochar at three concentrations (2.5%, 5%, and 10%) on bacterial counts and on the antimicrobial resistance and virulence profiles of Escherichia coli and Enterococcus isolates. The results show that biochar supplementation did not promote a significant reduction in bacterial numbers. Overall, there were no significant changes in the isolates' virulence or resistance profiles, and none of the isolates obtained were classified as high or moderate threats based on their MAR and VIR indexes. The most pathogenic Enterococcus isolates found were present in the control samples. A phylogenetic analysis of E. coli isolates allowed us to identify phylogroup D strains, predominantly in RMS supplemented with 2.5% and 10% biochar, which are associated with higher virulence and resistance. These findings indicate that the biochar concentrations tested were not effective in significantly reducing the bacterial risks associated with RMS. Further research is needed to evaluate different biochar formulations and concentrations, aiming to optimize its potential use for RMS supplementation.

Emergence of multi-drug-resistant, vancomycin-resistant, and multi-virulent Enterococcus species from chicken, dairy, and human samples in Egypt.

The present study aimed to detect the frequency of vancomycin resistance and virulence genes' profiles of multi-drug-resistant (MDR) enterococcal isolates from different sources and to investigate the sequence heterogeneity between the esp genes of MDR and vancomycin-resistant Enterococcus faecalis isolates from chicken and human sources. Conventional phenotypic methods identified 91 isolates (60.7%) as Enterococcus species, and these isolates were retrieved from dairy (37/52), chicken (35/54), and human (19/44) origins. Enterococcal isolates were frequently resistant to rifampin (67%), and 38.5% of the isolates were MDR. Of the 22 vancomycin-resistant enterococci (VRE) detected isolates, 11 (50%), 9 (41%), 1 (4.5%), and 1 (4.5%) isolate were identified as E. faecium, E. faecalis, E. casseliflavus, and un-specified Enterococcus spp., respectively. Moreover, 22 (100%) and 19 (86.4%) isolates harbored vanA and vanB genes, respectively. Of note, gelE and asa1 genes were more prevalent among the tested isolates (95.5% each), and the multi-virulence criteria were detected among 68.2% of the examined isolates. The sequences of esp genes of E. faecalis from the chicken breast meat and human urine samples were 100% identical with other esp genes and pathogenicity islands on GeneBank, which is undesirable. Our findings require strict hygienic measures during the processing of chickens and their by-products to minimize the possibility of transmission of virulent enterococcal strains. Furthermore, the use of antimicrobials in poultry and animal production in developing countries should be controlled to minimize the prevalence of MDR and VRE isolates in humans.

Surveillance and Characteristics of Vancomycin-Resistant Enterococcus Isolates in a Chinese Tertiary Hospital in Shenzhen, 2018 to 2024

ObjectiveTo investigate the prevalence and characteristics of vancomycin-resistant Enterococcus (VRE) isolates in a Chinese tertiary hospital in Shenzhen. MethodsA hospital-based retrospective epidemiological survey of Enterococcus was conducted over a 6.5-year period, from January 2018 to June 2024. The VRE isolates were identified and subjected to screening for the six van genes and multi-locus sequence typing (MLST) genotyping. The clinical characteristics, antimicrobial susceptibility profiles and molecular features were subjected to analysis. ResultsA total of 34 non-duplicate VRE isolates were identified, comprising 32 vancomycin-resistant Enterococcus faecium (VREfm) and 2 vancomycin-resistant Enterococcus faecalis (VREfa) strains. Since its initial isolation in 2022, there has been an observable increase in the detection rate of VRE. The detection rate of VRE between 2022 and 2024 (until June) was 0.3%, 4.8%, and 8.6%, respectively. The majority of the VRE strains were isolated from urine (25/34, 73.5%), and the highest detection rate (9.1%) of VRE infections was observed in the patients aged ≥75 years. In excess of 90% of VRE isolates exhibited resistance to ciprofloxacin (97.1%) and levofloxacin (97.1%), followed by ampicillin (94.1%) and penicillin (94.1%). The non-susceptible rate was observed to be low for linezolid (2.9%) and tigecycline (5.9%). Of the 29 VREfm isolates preserved and tested, 28 were found to harbour the vanA gene. A total of six STs were identified among the 29 VREfm isolates, with ST80 (16/29, 55.2%) being the predominant. The ST80 remained the most prevalent clone until the introduction of ST78 in May 2023, at which point these two clones became the most prevalent. ConclusionThere has been an observable increase in the prevalence of VRE in our hospital since 2022. Furthermore, an ongoing outbreak of ST80 and ST78 VREfm with vanA-harboring plasmid was identified. It is imperative that continuous surveillance be conducted in order to inform public health interventions.

Vancomycin-resistant Enterococcus – a study on its prevalence from different clinical samples in a rural medical college hospital

Background: Vancomycin-resistant Enterococcus (VRE) is an important cause of nosocomial infection with Enterococcus faecium causing most of the VRE infections. Widespread use of glycopeptides in health care facilities has led to the development of VRE and enterococcal infections with high-level resistance to aminoglycosides, beta-lactamase production and glycopeptide (including vancomycin) resistance are difficult to treat and often pose a therapeutic challenge to health care facilities. Aims and Objectives: This study aimed to determine the antibiotic susceptibility pattern of Enterococcus species from various clinical specimens and to find out the occurrence rate of vancomycin-resistant enterococci. Materials and Methods: This study was conducted at the Department of Microbiology of Tamralipto Government Medical College and Hospital, East Midnapore, West Bengal. A total of 688 clinical samples were the total sample size taken. Isolation and identification of Enterococcus spp. were done by standard microbiological procedures such as culture, Gram staining, and suitable biochemical tests were conducted. Antibiotic susceptibility testing was done by the Kirby–Bauers disc diffusion method on Mueller–Hinton agar and results were interpreted according to Clinical and Laboratory Standards Institute (CLSI) guidelines 2023. Teicoplanin sensitivity was performed for those isolates showing resistance to vancomycin. For strains showing resistance to vancomycin by the Kirby–Bauers disc diffusion method, vancomycin minimum inhibitory concentrations (MIC) were performed by E-test (Hi media) with MIC breakpoints between 4 and 32 as per CLSI criteria. This was compared with the control strain of American Type Culture Collection Enterococcus faecalis 29212 as per CLSI 2023 guidelines. Results: A total of 48 Enterococcus isolates were obtained from 688 clinical samples; 31 (8.05%) were detected from 385 urine samples, 9 (6.72%) were detected from 134 blood samples, 5 (5.15%) were detected from 97 pus/wound swab, and 3 (4.17%) were detected from 72 bronchoalveolar lavage fluid samples. Among the 48 Enterococcus isolates, 13 (27.08%) were vancomycin-resistant out of which nine were E. faecalis and four were E. faecium. Enterococcus species showed maximum resistance toward ciprofloxacin followed by ampicillin and maximum sensitivity toward teicoplanin and linezolid. Conclusion: Implementation of strict infection control measures, antimicrobial policies, and proper surveillance are required to identify, contain, and treat VRE infections to reduce mortality and morbidity.

From Isolation to Application: Utilising Phage-Antibiotic Synergy in Murine Bacteremia Model to Combat Multidrug-Resistant Enterococcus faecalis.

Enterococcus species, natural inhabitants of the human gut, have become major causes of life-threatening bloodstream infections (BSIs) and the third most frequent cause of hospital-acquired bacteremia. The rise of high-level gentamicin resistance (HLGR) in enterococcal isolates complicates treatment and revives bacteriophage therapy. This study isolated and identified forty E. faecalis clinical isolates, with 30% exhibiting HLGR. The HLGR5 isolate, resistant to fosfomycin, vancomycin, and linezolid, was used to isolate the vB_EfaS_SZ1 phage from effluent water. This phage specifically lysed 42% of HLGR isolates. vB_EfaS_SZ1 demonstrated beneficial traits, including thermal stability, acid-base tolerance, a short latent period, and a large burst size. The phage genome comprises a 40,942 bp linear double-stranded DNA with 65 open reading frames (ORFs). The genome closely resembled Enterococcus phages, classifying it within the Efquatrovirus genus. Phage-antibiotic synergy was assessed using checkerboard assays and time-killing analyses, revealing enhanced bacteriolytic activity of ampicillin and fosfomycin, with significant reductions in minimum inhibitory concentration values. In a mouse bacteremia model, phage-antibiotic combinations significantly reduced E. faecalis liver burden compared to monotherapies. Histopathological analysis confirmed therapeutic synergy, showing reduced inflammation and improved hepatocyte regeneration. These findings underscore the potential of phage vB_EfaS_SZ1 as an adjunct to antibiotic therapy for resistant enterococcal bacteremia.

Isolation and molecular detection of Enterococcus faecium from infected root canals: for progressing towards sustainability

Background and objectives. Enterococcus is a lactic acid bacterium that, according to the Lancefield method of serology-based classification, was formerly classified as a group D Streptococcus until 1984. The current study aimed to isolate and molecularly detect E. faecium (EF) from the infected root canal, and to assess the antimicrobial susceptibility of the isolates. Material and methods. Samples were collected from 50 people who had a single root canal tooth with radiographic evidence of apical periodontitis. The transport media were preincubated at 37°C for 30 minutes and vigorously agitated for 60s before use and were then cultured on primary media. Aerotolerance, Gram-staining, synthesis of catalase, trypsin, and indole were used in the preliminary characterization stage. For species-level identification after preservation at 37°C, a variety of biochemical tests were used, including motility tests, carbohydrate fermentation, and the detection of enzymes. DNA extraction was achieved using the PrestoTM Mini gDNA bacteria kit. Amplification of ddI chromosomal genes from EF was accomplished using DNA extracted from these isolates. Antimicrobial sensitivity tests were conducted to investigate the sensitivity and resistance of the target bacteria against 7 antimicrobial agents. Results. The analysis of data revealed that the prevalence of EF was 70% (in 35 of the samples collected). 74% of the Enterococcus isolates tested positive for EF according to PCR findings. The antibiotic sensitivity test results showed that vancomycin and erythromycin resistance was observed in all samples of EF. As many as 94.3% of isolates were resistant to amikacin, 88.7% were resistant to gentamycin, and 91.4 % were resistant to azithromycin. Doxycycline (94.3%) and nitrofurantoin (97.1%) were more effective against the E. faecium isolated from the root canals. Conclusions. The study concludes that the EF bacteria is an important pathogen of root canal infection which is resistant to many antibiotics.

Tracking the Prevalence of Antibiotic Resistance in Enterococcus Within the Spanish Poultry Industry: Insights from a One Health Approach.

Background/Objectives: Antimicrobial resistance (AMR) in Enterococcus species from poultry production represents a significant public health threat due to the potential transmission of AMR through the food chain. This study aimed to examine the relative prevalence, resistance patterns, and mannitol fermentation capacity of Enterococcus isolates from various poultry production systems in Spain over a seven-year period (2017-2023). Methods: A total of 215 Enterococcus isolates were analyzed. Phenotypic assessments were conducted to determine resistance rates and metabolic capacities, while genotypic characterization focused on detecting vancomycin-resistance genes (vanA, vanB, vanC, and vanD). Results: Enterococcus faecalis (62.3%) and Enterococcus faecium (29.77%) were the predominant species, primarily isolated from broilers (74.88%), with the highest frequency observed in one-week-old chicks (31.16%). High resistance rates to tetracyclines and streptogramins were identified, while resistance to vancomycin (0.47%) and tigecycline (3.03%) was low. Interestingly, a significant reduction in tetracyclines resistance was shown in this period for Enterococcus faecalis (from 100% to 70% (2017-2023) and Enterococcus faecium (from 100% to 40% (2018-2023)). Multidrug resistance (MDR) was detected in 26.98% of isolates. Mannitol fermentation tests revealed high metabolic capacity in Enterococcus faecalis (99.25%) and Enterococcus faecium (96.88%), associated with adaptability and virulence potential. Genotypic analysis showed a very low prevalence of vanB and vanC genes. Conclusions: These findings highlight the critical need for targeted surveillance and intervention strategies in poultry production to mitigate the risks posed by MDR Enterococcus to public health.

Antimicrobial resistance patterns and virulence determinants of clinical enterococcus isolates in Pakistan

Background. The current study was designed to determine antibiotic resistance profile,detection of antimicrobial resistance and virulence-related genes among enterococcus species. Materials and methods. Altogether, one hundred fifty enterococcal isolates were collected from various clinical specimens and identified by Polymerase chain reaction (PCR). Antibiotic susceptibility testing and MICs of vancomycin were carried out as per CLSI guidelines. A series of PCR reactions were used to screen vancomycin-resistant genes (vanA, vanB, and vanD) and virulence-related genes (esp, ace, asa1, gelE cylA) among VRE enterococcus species. Results. The isolated enterococcal strains comprised 62.6% E. faecalis, 33.4% E. faecium, and 4% of other species. Overall enterococcus showed a high level of resistance; 94% to erythromycin, followed by ciprofloxacin 82.6%, levofloxacin 70%, and vancomycin 16%. The 57.4% of the isolates were recovered from hospitalized patients and 96% of the enterococcus isolates were multi-drug resistant. The MICs of vancomycin-resistant strains remained in the range of 32 µg/ml to 256 µg/ml for the majority of the isolates. The vancomycin-resistant phenotypes vanA, vanB, and vanD were found in 29.2%, 37.5%, and 33.3% isolates respectively. Regarding virulence determinants the observed percentages were as follows; esp: 16.6%, asa1: 70.8%, gelE: 25%, ace: 33.3%, and cylA: 25%. Conclusion. The majority of the isolates were E. faecalis and multi-drug resistant. The VRE isolates carried antimicrobial resistance and virulence-related genes, and vanA, B, D phenotypes were the most common among VRE isolates.

Australian Group on Antimicrobial Resistance (AGAR) Australian Enterococcal Surveillance Outcome Program (AESOP) Bloodstream Infection Annual Report 2023.

From 1 January to 31 December 2023, fifty-six institutions across Australia participated in the Australian Enterococcal Surveillance Outcome Program (AESOP). The aim of AESOP 2023 was to determine the proportion of enterococcal bacteraemia isolates in Australia that were antimicrobial resistant, and to determine the Enterococcus faecium molecular epidemiology. Of the 1,599 unique episodes of enterococcal bacteraemia investigated, 92.9% were caused by either E. faecalis (51.8%) or E. faecium (41.1%). Ampicillin and vancomycin resistance were not detected in E. faecalis but were detected in 94.2% and 50.8% of E. faecium respectively. Two linezolid-resistant E. faecalis were identified in 2023. Both isolates had linezolid minimum inhibitory concentrations (MICs) of 6.0 mg/L, were vancomycin susceptible, and harboured the optrA gene. Overall, 53.2% of E. faecium harboured either the vanA or the vanB gene; of these, 27.3% harboured vanA, 72.1% harboured vanB, and 0.6% harboured vanA and vanB. The percentage of vancomycin-resistant E. faecium bacteraemia isolates in Australia remains substantially higher than that recorded in most European countries. The E. faecium isolates consisted of 58 multi-locus sequence types (STs); 85.7% of isolates were classified into seven major STs, each containing ten or more isolates. All major STs belonged to clonal complex (CC) 17, a global hospital-adapted polyclonal E. faecium CC. The major STs (ST78, ST1424, ST17, ST80, ST796, ST1421 and ST555) were found across most regions of Australia, with ST78 identified in all regions. Overall, 58.3% of isolates belonging to the seven major STs harboured the vanA or vanB gene. AESOP 2023 has shown that enterococcal bacteraemia episodes in Australia continues to be frequently caused by polyclonal ampicillin-resistant high-level gentamicin-resistant vanA- or vanB-positive E. faecium which have limited treatment options.

Prevalence of Vancomycin-Resistant Van A and Van B Genes in ESKAPE Gram-Positive Bacteria Isolated from Hospitalized Patients in Mashhad, Iran

Introduction: The ESKAPE group, comprising Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterococcus faecium, is known for its role in hospital-acquired infections and its growing resistance to antimicrobial agents. This resistance complicates treatment options, particularly with last-resort antibiotics, such as vancomycin. This study aims to determine the prevalence of vancomycin-resistant genes (Van A and Van B) in Staphylococcus aureus and Enterococcus species isolated by polymerase chain reaction (PCR) method from hospitalized patients in Mashhad, Iran. Materials and Methods: A total of 1000 clinical samples were collected over six months from hospitalized patients in four hospitals in Mashhad, Iran. The samples included blood, urine, wound swabs, and respiratory secretions. Staphylococcus aureus and Enterococcus isolates were identified through standard microbiological tests. Vancomycin susceptibility was assessed using the E-test method. The presence of vancomycin-resistant genes (Van A and Van B) was determined by PCR method. Results: Out of a total of 98 bacterial isolates, 77 were identified as Staphylococcus aureus and 21 as Enterococcus species. Among the Enterococcus isolates, 15 were identified as Enterococcus faecium and 6 as Enterococcus faecalis. Vancomycin resistance genes were detected in 7 isolates in total, with 6 of these isolates harboring the Van A gene and 1 carrying the Van B gene. Conclusion: The study reveals 40% and 1.3% prevalences of vancomycin resistance in Enterococcus faecium and Staphylococcus aureus isolates, respectively. These findings underscore the critical need for vigilant antibiotic stewardship and the implementation of appropriate treatment strategies to effectively manage infections caused by these resistant pathogens.

Prevalence of Vancomycin-Variable Enterococci from the Bloodstream in the Korea Global Antibiotic Resistance Surveillance System, 2017-2022.

Vancomycin-variable enterococci (VVE), though genetically containing van genes, are phenotypically sensitive to vancomycin. If VVE is undetected or does not grow on the vancomycin-resistant enterococci (VRE) selection medium, or both, it can acquire resistance upon exposure to vancomycin. This characteristic is clinically important for the treatment and prevention of VRE. This study aims to analyze the prevalence and characteristics of VVE in Korea through the Global Antibiotic Resistance Surveillance System (Kor-GLASS) and emphasize the importance of VVE. A total of 3342 enterococcal bloodstream isolates were collected through the Kor-GLASS between 2017 and 2022. Antibiotic susceptibility testing, van gene detection, and multilocus sequence typing were conducted with all the isolates. The trends in the domestic prevalence of VVE were analyzed and compared with global prevalence data. Among the isolates, 197 (5.9%), including 124 Enterococcus faecium and 73 E. faecalis, were identified as VVE. While the VRE incidence has declined in Korea since 2020, the VVE incidence is significantly rising. In Korea, only the vanA gene has been detected in both VRE and VVE, and no other van gene variants have been identified. Most of these isolates belong to CC17 (91.3%), with ST17, ST817, and ST80 as the predominant types. We have shown that continuous surveillance is essential in Korea due to the persistently high prevalence of VRE and the potential evolution of VVE into VRE. Consequently, it is critical to evaluate Enterococcus species isolated from domestic clinical settings for their phenotypic vancomycin resistance and the molecular detection of van genes, irrespective of the strain.

Bacteriocin-Producing Enterococci Modulate Cheese Microbial Diversity

Cheese production involves various lactic acid bacteria (LAB) that break down lactose, milk proteins, and fats, producing key nutrients and influencing the cheese’s flavor. They form communities that play a crucial role in determining the cheese’s organoleptic properties. The composition of cheeses’ microbial communities is shaped by physicochemical factors (e.g., temperature, pH, and salinity) and biological factors (i.e. microbial interactions). While starter cultures are introduced to control these communities, non-starter LAB represent a significant portion of the final microbial assemblage, but their interactions remain unclear. LAB often produce bacteriocins, antimicrobial peptides that antagonize other bacteria, but their role within LAB communities is not fully understood. This study aimed to assess the impact of bacteriocin production on LAB diversity in cheese, using Enterococcus as a model organism, a common bacteriocin producer. We analyzed enterocin production of enterococcal isolates by antimicrobial assays and microbial diversity differences in raw milk cheeses by two approaches: 16S RNA gene amplicon metagenomic sequencing for the whole microbial community and multi-locus sequence analysis (MLSA) for the enterococcal diversity. Our results revealed that LAB communities were dominated by lactococci, lactobacilli, and streptococci, with enterococci present in lower numbers. However, cheeses containing bacteriocin-producing enterococci exhibited higher microbial diversity. Interestingly, the highest diversity occurred at low levels of bacteriocin producers, but this effect was not observed within enterococcal populations. These findings suggest that bacteriocin production plays a key role in shaping LAB communities during cheese ripening, although further research is needed to understand its broader implications in other microbial ecosystems.

Study of probiotic properties of Enterococcus isolates isolated from natural biotopes

Study of probiotic properties of Enterococcus isolates isolated from natural biotopes

Antimicrobial resistance, virulence gene profiles, and molecular epidemiology of enterococcal isolates from patients with urinary tract infections in Shanghai, China.

This study highlighted the critical need to understand Enterococcal strains causing UTIs in Shanghai, given their high prevalence. By assessing antimicrobial resistance profiles, virulence gene presence, and molecular epidemiology, the research offered valuable insights into the local epidemiology of Enterococcus faecalis and Enterococcus. faecium. Identifying linezolid-resistant strains, all of which carry the optrA gene, including the first report of ST300 in China and recognizing dominant MLST types, such as ST16 and ST179 for E. faecalis and ST78 for E. faecium, are vital for guiding treatment and addressing the challenges these infections present. The data emphasize the need for ongoing surveillance and customized therapeutic approaches to combat emerging resistance and virulence factors in Enterococcal UTIs.

One Health Approach of Enterococcal Population Structure and Antibacterial Resistance Along the Food Chain - Four PLADs, China, 2015-2022.

Enterococci are considered opportunistic pathogens. However, they can serve as a reservoir of antibacterial resistance (ABR) traits and transfer these to humans through the food chain. Antibiotic susceptibility testing and multilocus sequence typing were used to characterize the ABR and population structure of 488 enterococcal isolates recovered along the food chain from four provincial-level administrative divisions (PLADs) in China. Enterococcus faecalis (E. faecalis) was the dominant species cultured from pig farms and retail meat, while Enterococcus faecium (E. faecium) and Enterococcus casseliflavus were dominant in patients with diarrhea and retail fruits and vegetables, respectively. Approximately 67% of all Enterococcus isolates were multidrug-resistant (MDR). E. faecium resistance to ampicillin and penicillin was significantly higher than that of E. faecalis. The E. faecalis isolates exhibited substantially heterologous sequence types (STs), whereas E. faecium isolates were clearly divided into clonal complex (CC) CC17 and CC94 clades. E. faecium isolates were mainly detected in hospitalized children and were identified as the hospital-associated CC17 clade with ampicillin and penicillin resistance. Notably, E. faecalis ST16 and ST65 and E. faecium ST60 and ST94 detected in patients with diarrhea were also detected in farm and food samples, indicating that these STs should be closely monitored. The community-lineage E. faecium CC94 clade was detected in patients with diarrhea, implying that community isolates might find their way into hospitals. This study highlights the One Health challenges posed by enterococci important to human health and the need to implement integrated preventive measures for their control.

Antimicrobial Resistance Profile of Enterococcal Isolates From Clinical Specimens at a Tertiary Care Hospital in Western Maharashtra, India.

Background Enterococcus, once benign intestinal flora, has transformed into formidable nosocomial pathogens as a result of the accelerated emergence of antibiotic resistance represents a major global health challenge, particularly within hospital settings. Enterococcus has grown more prevalent in nosocomial infections, such as urinary tract infections (UTIs), surgical site infections (SSIs) and bacteremia. The potential emergence of vancomycin-resistant Enterococcus(VRE) strains further complicates treatment choices for multi-drug resistant (MDR) infections. This study evaluated the magnitude of Enterococcus infections and their antibiotic resistance patterns in a tertiary care hospital. Material and methods A laboratory-based cross-sectional study was conducted from January 2023 to December 2023 (one year) at Krishna Hospital & Medical Research Centre, Karad, India. A total of 189 enterococcalisolates were identified from various clinical specimens, including urine, blood, pus, and other samples. These isolates were subjected to identification and antimicrobial susceptibility testing using the automated VITEK 2 (bioMérieux SA, Marcy-l'Étoile, France) system.VanA and VanB phenotypes were detected based on minimum inhibitory concentration (MIC) values using the VITEK 2 Advanced Expert System (AES) system (bioMérieux SA). Statistical analysis was done using StatisticalPackage for the Social Sciences (IBM SPSS Statistics for Windows, IBM Corp., Version 21.0, Armonk,NY). Results Among 189 culture-positive enterococcal isolates, the majority were obtained from urine 144 (76%), followed by blood 17 (9%), pus 12 (6%), etc. A larger proportion of these isolateswere from femalepatients 97 (51%) aged over 60 years. A substantial proportion of these isolates originated from in-patient departments (IPD) 178 (94.2%) with intensive care units contributing the highest number 114 (60%) and out-patient departments (OPD) 11 (5.8%). The highest prevalence of infection was observed among patients with a hospital stay of 8 to 14 days (32.3%). E. faecium (57.7%) and E. faecalis (39.6%) were the predominant species with E. faecium displaying significant resistance to benzylpenicillin (96%) and nitrofurantoin (94%) whereas E.faecalis showed higher resistance to high-level gentamicin (80%). E. gallinarum (1.6%)showed complete resistance to benzylpenicillin (100%) and moderate resistance to nitrofurantoin (67%), and high-level gentamicin (67%). Conversely, E. durans showed complete resistance (100%) to both nitrofurantoin and benzylpenicillin. Among 31 VREisolates, 16 (52%) showed the VanA and 15 (48%) showed the VanB phenotype. Conclusion Antimicrobial resistance among E. faecium and E. faecalis, particularly to benzylpenicillin, high-level gentamicinand nitrofurantoinalong with the emergence of resistant species like E. durans and E. gallinarum underscores the urgent need for vigilant antimicrobial stewardship and continuous surveillance of the growing threat of MDRenterococci in clinical settings.