Characterization of Vancomycin Resistant Enterococci in Hospitalized Patients and Role of Gut Colonization

High Gastrointestinal Colonization Rate of Vancomycin-Resistant Enterococci among Hospitalized Patients: Potential Source for Resistant Gene

Background

Vancomycin-resistant Enterococci (VRE) is a global health problem and responsible for healthcare-associated infections (HAIs) in patients with prolonged hospital stay, severe underlying disease, and previous broad-spectrum antibiotic therapy. These bacteria can cross-resist and transfer drug-resistant genes to other potentially pathogenic bacteria. Therefore; this study was aimed to determine the gastrointestinal colonization rate of VRE, its antimicrobial susceptibility profile, and associated factors among hospitalized patients.

Methods

Prospective cross-sectional study was conducted using stool samples from 223 patients admitted to different wards at Hawassa University Comprehensive Specialized Hospital, from April 1 to June 30, 2021. Patients admitted to the hospital for more than 48 hours for various medical conditions were included. Sociodemographic and clinical characteristics were collected using a structured questionnaire. Fecal specimens were cultured on Enterococci selective media. Enterococcus species were identified using their growth and mannitol fermentation properties. Vancomycin resistance was screened using both the Kirby-Bauer disk diffusion method and a vancomycin E-test strip. Data were entered and analyzed using SPSS version 25. Descriptive and logistic regressions were used to determine the frequency and association of factors with the VRE colonization rate. A p value of <0.05 was considered statistically significant.

Results

A total of 223 fecal specimens were collected and processed, and 141 (63.2%) them were positive for Enterococci. The predominant species was E. faecalis 65 (46.1%) followed by E. faecium 76 (53.9%). In this study, the gastrointestinal colonization rate of VRE was 15 (6.7%) and all the species belong to E. faecium. Study participants who had no formal education (AOR = 4.26, 95% CI: 1.01, 18.06), hospitalized patients for >2 weeks (AOR = 4.10, 95% CI: 1.08, 15.57), and those who had a history of treatment with vancomycin (AOR = 4.77, 95% CI: 1.26, 18.09) were more likely to be colonized with vancomycin-resistant Enterococci. More than 95% of Enterococci isolates were susceptible to linezolid, whereas 70.2%, 63.1%, 56.7%, and 53.9% were resistant to tetracycline, erythromycin, penicillin, and ampicillin, respectively. Among the total Enterococci isolated, 141 (54.6%) were multidrug resistant.

Conclusions

In our study, high proportion of vancomycin-resistant Enterococci was found. Previous exposure to antibiotics and hospital stay were significant factors for VRE gut colonization. The isolated Enterococci showed variable degrees of resistance to commonly prescribed antibiotics which leads to a worldwide problem multidrug resistance. Therefore, periodic surveillance on antimicrobial resistance pattern, adhering to rational use of antibiotics, and implementing infection prevention protocols may reduce colonization by VRE.

Prevalence of vancomycin-resistant Enterococci in India between 2000 and 2022: a systematic review and meta-analysis

BACKGROUND

Vancomycin-resistant Enterococci (VRE) infections are recurrently reported in different parts of India in the last two decades. However, an up-to-date, countrywide information concerning the prevalence and the rate of VRE in India is limited and hence this study aimed to estimate the pooled prevalence of VRE in India.

METHODS

A literature search was performed using various databases. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed throughout. Cross-sectional studies reporting the prevalence of VRE in India from human samples whereby at least two Enterococci were isolated between 1 January 2000 and 31 December 2022 were sought for inclusion. Data were extracted and analysed using Microsoft Excel and Comprehensive Meta-analysis version 4, respectively.

RESULTS

Nineteen studies were included in the analyses. A collective total of 3683 Enterococci isolates were examined, of which 368 were VRE strains. The pooled prevalence of VRE in India was calculated at 12.4% (95% CI: 8.6-17.5; Q = 189.69; I2 = 90.51%; p = < 0.001). E. faecalis was the most frequently isolated species (1450 [39.37%]) followed by E. faecium (724 [19.66%]). Amongst the VRE strains, E. faecium was the most prevalent (214 [58.15%]) followed by E. faecalis (134 [36.41%]). An upsurge in the rate of VRE infections was observed in India over time: VRE prevalence was estimated at 4.8% between 2000 and 2010 and 14.1% between 2011 and 2020.

CONCLUSION

This study presents the most up-to-date information on the rate of VRE infections in India. Though lower than the findings for some less developed countries, VRE prevalence in India is notable and on the rise.

Vankomisine Dirençli Enterococcus faecium: Kısa Bir Derleme

Antimikrobiyal direnç (AMD) ile ilişkili morbidite ve mortalite küresel bir halk sağlığı sorunudur. Sağlık hizmeti ilişkili enfeksiyonlarda sık olarak görülen vankomisine dirençli Enterococcus faecium (VRE), Dünya Sağlık Örgütü’nün AMD’i olan öncelikli patojenler listesinde yüksek öncelik verdiği bir Gram pozitif koktur. Son zamanlarda Türkiye’de invaziv enfeksiyonlarda VRE izolasyon oranı %15.8 bildirilmiştir. Vankomisine direncin ana mekanizması, hedef bölgedeki D-Alanil-D-Alanin terminal molekülünün değişmesi ve ilacın affinitesinin azalmasıdır. Vankomisin direncinden sorumlu olan van geni kromozomal olarak kodlanmakta veya plazmid, transpozon gibi mobil genetik elemanlar ile kazanılmaktadır. Yayılımındaki ana mekanizma, mobil genetik elemanların Enterokoklar veya Staphylococcus aereus gibi farklı tür bakteriler arasında transfer edilebilmeleridir. Bu derlemede PubMed ve Web of Science veritabanlarında “Vankomisin-dirençli Enterococcus faecium”, “Vankomisin direnç mekanizmaları”, “Gram pozitif koklarda vankomisin direnci” terimleri ile arama yapılarak elde edilen literatür verileri özetlenmiş ve önerilerle birlikte kısaca tartışılmıştır.

A Review of Detection Methods for Vancomycin-Resistant Enterococci (VRE) Genes: From Conventional Approaches to Potentially Electrochemical DNA Biosensors

Vancomycin-resistant Enterococci (VRE) genes are bacteria strains generated from Gram-positive bacteria and resistant to one of the glycopeptides antibiotics, commonly, vancomycin. VRE genes have been identified worldwide and exhibit considerable phenotypic and genotypic variations. There are six identified phenotypes of vancomycin-resistant genes: VanA, VanB, VanC, VanD, VanE, and VanG. The VanA and VanB strains are often found in the clinical laboratory because they are very resistant to vancomycin. VanA bacteria can pose significant issues for hospitalized patients due to their ability to spread to other Gram-positive infections, which changes their genetic material to increase their resistance to the antibiotics used during treatment. This review summarizes the established methods for detecting VRE strains utilizing traditional, immunoassay, and molecular approaches and then focuses on potential electrochemical DNA biosensors to be developed. However, from the literature search, no information was reported on developing electrochemical biosensors for detecting VRE genes; only the electrochemical detection of vancomycin-susceptible bacteria was reported. Thus, strategies to create robust, selective, and miniaturized electrochemical DNA biosensor platforms to detect VRE genes are also discussed.

Detection of Vancomycin-Resistant Enterococci and Vancomycin Resistance Genes in Patients Hospitalized in the Pediatric Intensive Care Unit

Objective: Vancomycin-resistant enterococci (VRE) infection and colonization are seen increasingly frequently, especially among intensive care unit (ICU) patients. In this study, the aim was to detect VRE in swab samples taken from patients hospitalized in the Pediatric ICU (PICU), colonization, and to investigate the clonal relationship between isolates. Materials and Methods: In the present study, swab samples were taken from the external auditory canal (EAC), umbilical region, and rectal region from 82 patients hospitalized in the Çukurova University Balcalı Hospital PICU. The 246 swab samples from patients were inoculated on Kanamycin-Esculin-Azide agar. Isolates were identified with the help of the BBL Crystal Gram-Positive identification system. The susceptibility of the isolates to vancomycin (30 µg) was investigated by Kirby-Bauer disk diffusion method according to CLSI criteria. VanA-VanB genes in phenotypically defined vancomycin-resistant enterococci were investigated by Polymerase Chain Reaction (PCR) method. The clonal relationship between vancomycin-susceptible (VSE) and -resistant enterococci was determined by the SmaI-PFGE method. Results: A total of 49 (20.3%) enterococcal strains were isolated from 246 swab samples from the patients, of which 14 (28.5%) were VRE. Of the enterococci isolates, 27 (55.10%) were E. faecium and 13 (26.53%) were E. feacalis. While VanA type resistance was detected in 11 of the vancomycin-resistant E. faecium and E. feacalis isolates, VanB type resistance was not detected in any sample. There was no significant clonal relationship between the isolates. Conclusion: Although the prevalence of VRE in the PICU was high throughout the study, no enterococcal infection was observed.

High-level gentamicin resistance mediated by Aac(6')-Ie-aph(2")-Ia gene in Enterococcus species isolated from clinical samples in Northern India

CONTEXT

Enterococci are known to cause life-threatening infections which are difficult to treat as the organism harbors innate resistance to many antibiotics and can amass resistance toward many others through plasmid-mediated genetic exchange.

AIMS

The study evaluates the drug susceptibility profile of various Enterococcus species isolated from various patient specimens submitted for bacteriological analysis and check the incidence of aac(6') Ie-aph(2") Ia gene.

SETTING AND DESIGN

This in vitro cross-sectional study was executed at bacteriology laboratory of a 470 bedded hospital in New Delhi.

MATERIALS AND METHODS

Drug susceptibility testing was carried out on enterococcal isolates. High-level gentamicin-resistant (HLGR) isolates detected by micro broth dilution assay were then subjected to molecular detection of aac(6') Ie-aph(2") Ia gene.

STATISTICAL ANALYSIS USED

The level of significance was established by Chi-square test.

RESULTS

Among the 182 enterococcal stains detected, 76.9% were Enterococcus faecalis and 20.3% were Enterococcus faecium. 12.08% strains were vancomycin resistant. 39% expressed resistance toward high-level gentamicin (HLG) and this finding was significantly higher in E. faecium than E. faecalis. HLGR strains expressed a higher degree of resistance to other drugs in contrast to non-HLGR isolates. In 67 out of 71 HLGR isolates the bifunctional gene was detected.

CONCLUSION

Considerable presence of HLG and vancomycin resistance in the clinical isolates is alarming and should be taken seriously. The study shows high dissemination of aac(6')-Ie-aph(2")-Ia gene among Enterococci isolated from the region.

Increasing Trend of Vancomycin-resistant Enterococci Bacteremia in a Tertiary Care Hospital of South India: A Three-year Prospective Study

Introduction: Vancomycin-resistant enterococci (VRE) are emerging as an important multidrug-resistant pathogen causing nosocomial infections, predominantly bacteremia and urinary tract infections. VRE bacteremia has caused a significant increase in the duration of the hospital stay and mortality and had caused high public health threat due to limited treatment options.

Materials and methods: Between October 2017 and September 2020, all consecutive patients with culture-proven bloodstream infection with Enterococcus species, isolated for the first time, were included in the study. A total of 427 Enterococcus species were identified, and antimicrobial susceptibility tests were performed and interpreted using Clinical and Laboratory Standard Institute guidelines.

Results: Of the total 427 Enterococcus species isolated, 63 (45.6%) were VRE. Among them, 51/63 (81%) were Enterococcus faecium (E. faecium) and 5/63 (8%) were Enterococcus faecalis. There was an increased trend of VRE rate in the bloodstream infections of 6.12% (2018), 13.2% (2019), and 19.2% (2020). The majority of the VRE patients [43/63 (68%)] were admitted to the intensive care units (ICUs). Vancomycin A (VanA) is the most common phenotype isolated from 51/63(81%) patients.

Conclusion: This increasing trend of VRE bacteremia is a red alert to the clinicians and the infection control practitioners, so that strict antibiotic policies and proper adherence to the infection control practices can be initiated to reduce the VRE rate.

How to cite this article: Sivaradjy M, Gunalan A, Priyadarshi K, Madigubba H, Rajshekar D, Sastry AS. Increasing Trend of Vancomycin-resistant Enterococci Bacteremia in a Tertiary Care Hospital of South India: A Three-year Prospective Study. Indian J Crit Care Med 2021;25(8):881–885.

The Increasing Issue of Vancomycin-Resistant Enterococci and the Bacteriocin Solution

Enterococci are commensals of human and other animals’ gastrointestinal tracts. Only making up a small part of the microbiota, they have not played a significant role in research, until the 1980s. Although the exact year is variable according to different geographical areas, this was the decade when vancomycin-resistant enterococci (VRE) were discovered and since then their role as causative agents of human infections has increased. Enterococcus faecium is on the WHO’s list of “bacteria for which new antibiotics are urgently needed,” and with no new antibiotics in development, the situation is desperate. In this review, different aspects of VRE are outlined, including the mortality caused by VRE, antibiotic resistance profiles, animal-modeling efforts, and virulence. In addition, the limitations of current antibiotic treatments for VRE and prospective new treatments, such as bacteriocins, are reviewed.

Antibiogram of Urinary Enterococcus Isolates from a Tertiary Care Hospital

PURPOSE

Urinary tract infection (UTI) is one of the serious infections caused by the bacteria Enterococci. Vancomycin-Resistant Enterococci (VRE) is a persevering clinical problem globally. This study aims to detect high-level aminoglycoside and vancomycin resistance in uropathogenic Enterococcus spp.

METHODOLOGY

A total of 75 clinically relevant Enterococcus spp. grown from urine samples, were collected following convenience non-random sampling method. Identified by standard biochemical tests and susceptibility to antibiotics was studied by Kirby Bauer's disc diffusion method. The MIC of vancomycin was detected by agar dilution test. Van A, and Van B genes in VREs were detected by PCR.

RESULTS

Among 75 Enterococcal isolates, 43 (57.3%) were E. faecalis, 12 (16%) were E. faecium, 6 (8%) of each were E. pseudoavium and E. casseliflavus, 5(6.66%) were E. dispar and 3 (4%) were E. durans. E. faecalis (n=19) and E. faecium (n=3) were resistant to High Level Streptomycin (HLS). E. faecalis (n=21) and E. faecium (n=6) were resistant to High Level Gentamicin (HLG). 4 (9.3%) E. faecalis were vancomycin-resistant, out of which 3 were of Van A, and one was both Van A and Van B genotype.

CONCLUSION

Isolation of high level aminoglycoside resistant (HLAR) Enterococci is a challenge for the treating physician because aminoglycoside cannot be used in combination with glycopeptide or ampicillin for such isolates. The occurrence of HLAR, Van A, and Van B VRE genotypes is a cause of concern as they may transfer drug resistance genes to other bacterial isolates, thus leading to limited therapeutic options.

Antimicrobial susceptibility profile & resistance mechanisms of Global Antimicrobial Resistance Surveillance System (GLASS) priority pathogens from India

Antimicrobial resistance is a major concern globally. Infections due to drug-resistant pathogens are becoming difficult and a challenge to treat. As treatment choices are limited due to the high-drug resistance rates, there is an increase in the health care cost, duration of hospital stay, morbidity and mortality rates. Understanding the true burden of antimicrobial resistance for a geographical location is important to guide effective empirical therapy. To have a national data, it is imperative to have a systemic data capturing across the country through surveillance studies. Very few surveillance studies have been conducted in India to generate national data on antimicrobial resistance. This review aims to report the cumulative antibiogram and the resistance mechanisms of Global Antimicrobial Resistance Surveillance System (GLASS) priority pathogens from India.

Assessing the intestinal carriage rates of vancomycin-resistant enterococci (VRE) at a tertiary care hospital in Hungary

Excessive use of antibiotics contributes to the selection of resistant bacteria and intestinal colonization with multiresistant pathogens poses a risk factor for subsequent infections. The present study assessed vancomycin-resistant enterococci (VRE) carriage rates in patients admitted to our tertiary care hospital. Stool samples sent for routine culturing were screened with vancomycin containing solid or broth enrichment media. VRE isolates were identified with matrix-assisted laser desorption/ionization-time of flight mass spectrometry and antibiotic susceptibilities were tested by E-test. Vancomycin resistance genes were detected by polymerase chain reaction. Medical records of carriers were examined for suspected risk factors for colonization. Altogether 3025 stool specimens were analyzed. Solid media identified a VRE carriage rate of 2.2% while broth enrichment detected 5.8%. Seventy percent of the isolates were Enterococcus faecium. VanB genotype was detected in 38.2%, VanA in 37.3%, VanC1 in 22.6%, and VanC2 in 1.9%. All VRE were sensitive to linezolid, daptomycin, and tigecycline. Collective risk factors for carriage were diabetes, normal flora absence, Clostridioides difficile positivity, longer hospital stay, and advanced age. 78.5% of the carriers received antibiotic therapy which was metronidazole in most cases (47.3%). We recommend regular screening of risk groups such as patients with diabetes, history of recent hospitalization, or former C. difficile infection as an imperative step for preventing VRE dissemination.

Study of vancomycin and high-level aminoglycoside-resistant Enterococcus species and evaluation of a rapid spot test for enterococci from Central Referral Hospital, Sikkim, India

BACKGROUND:

Enterococcus is an important pathogen, and with its emergence of resistance to multiple antimicrobials, the management of infection is becoming increasingly difficult.

AIM:

The aim of the study is to determine the prevalence, antibiotic resistance, and risk factors associated with enterococcal infection or colonization.

MATERIALS AND METHODS:

In this prospective study, samples from inpatients were screened for resistant enterococci. Antibiotic susceptibility testing was performed using the disc diffusion method and minimum inhibitory concentration by the agar dilution method. A modification of a test tube method of sodium chloride-esculin hydrolysis to a spot test was evaluated for its rapidity and reliability in the presumptive diagnosis of enterococci.

STATISTICAL ANALYSIS USED:

Fisher's exact test was used for continuous (Student's t-test) and categorical variables. Multivariate analysis was performed with logistic regression using IBM SPSS 20.0 software (Armonk, NY, USA).

RESULTS:

Enterococcus species were isolated from 182 samples: Enterococcus faecalis (68.7%), Enterococcus faecium (20.9%), Enterococcus gallinarum (6%), and Enterococcus durans (4.4%). Maximum resistance was to ciprofloxacin (59.3%) and least to linezolid (0.5%). The isolation rate of vancomycin-resistant enterococci (VRE) was 13.7%; 30.2% and 20.9% were of high-level gentamicin and streptomycin, respectively. All 182 Enterococcus species gave positive results within 30–60 min by the rapid spot test.

CONCLUSIONS:

Overall, high-level aminoglycoside resistance (HLAR) was observed more than glycopeptide resistance. Surveillance strategies need to be upgraded and implemented in order to prevent the emergence and further spread of not only VRE but also HLAR enterococci in the hospital. The spot test gave reliable and rapid results in presumptive identification of enterococci.

Current Perspectives on Treatment of Gram-Positive Infections in India: What Is the Way Forward?

The emerging antimicrobial resistance leading to gram-positive infections (GPIs) is one of the major public health threats worldwide. GPIs caused by multidrug resistant bacteria can result in increased morbidity and mortality rates along with escalated treatment cost and hospitalisation stay. In India, GPIs, particularly methicillin-resistant Staphylococcus aureus (MRSA) prevalence among invasive S. aureus isolates, have been reported to increase exponentially from 29% in 2009 to 47% in 2014. Apart from MRSA, rising prevalence of vancomycin-resistant enterococci (VRE), which ranges from 1 to 9% in India, has raised concerns. Moreover, the overall mortality rate among patients with multidrug resistant GPIs in India is reported to be 10.8% and in ICU settings, the mortality rate is as high as 16%. Another challenge is the spectrum of adverse effects related to the safety and tolerability profile of the currently available drugs used against GPIs which further makes the management and treatment of these multidrug resistant organisms a complex task. Judicious prescription of antimicrobial agents, implementation of antibiotic stewardship programmes, and antibiotic policies in hospitals are essential to reduce the problem of drug-resistant infections in India. The most important step is development of newer antimicrobial agents with novel mechanisms of action and favourable pharmacokinetic profile. This review provides a synopsis about the current burden, treatment options, and the challenges faced by the clinicians in the management of GPIs such as MRSA, Quinolone-resistant Staphylococcus, VRE, and drug-resistant pneumococcus in India.