Vancomycin-resistant enterococci (VRE): transmission and control

Analysis of molecular epidemiological characteristics and antimicrobial susceptibility of vancomycin-resistant and linezolid-resistant Enterococcus in China

BACKGROUND

This study investigates the distribution and characteristics of linezolid and vancomycin susceptibilities among Enterococcus faecalis (E. faecalis) and Enterococcus faecium (E. faecium) and explores the underlying resistance mechanisms.

METHODS

A total of 2842 Enterococcus clinical isolates from patients were retrospectively collected, and their clinical data were further analyzed. The minimum inhibitory concentrations (MICs) of vancomycin and linezolid were validated by broth dilution method. The resistance genes optrA, cfr, vanA, vanB and vanM were investigated using polymerase chain reaction (PCR). Housekeeping genes and resistance genes were obtianed through whole-genome sequencing (WGS).

RESULTS

Of the 2842 Enterococcus isolates, 88.5% (2516) originated from urine, with E. faecium accounted for 60.1% of these. The vanA gene was identified in 27/28 vancomycin resistant Enterococcus (VRE) isolates, 4 of which carried both vanA and vanM genes. The remaining strain was vanM positive. The optrA gene was identified in all E. faecalis isolates among linezolid resistant Enterococcus (LRE). E. faecium showed a higher multiple antibiotic resistance index (MAR index) compared to E. faecalis. The multi-locus sequence typing (MLST) showed the sequence type of E. faecium mainly belongs to clonal complex (CC) 17, nearly E. faecalis isolates analyzed were differentiated into 7 characteristics of sequence types (STs), among which ST16 of CC16 were the major lineage.

CONCLUSION

Urine was the primary source of VRE and LRE isolates in this study. E. faecium showed higher levels of resistance compared to E. faecalis. OptrA gene was detected in 91.6% of LRE, which could explain linezolid resistance, and van genes were detected in all vancomycin resistant Enterococcus strains, while vanA was a key resistance mechanism in VRE identified in this study.

Antibiotic susceptibility and genome analysis of Enterococcus species isolated from inpatients in one hospital with no apparent outbreak of vancomycin-resistant Enterococcus in Japan

To prevent nosocomial infection, it is important to screen for potential vancomycin-resistant Enterococcus (VRE) among patients. In this study, we analyzed enterococcal isolates from inpatients in one hospital without any apparent outbreak of VRE. Enterococcal isolates were collected from inpatients at Hiroshima University Hospital from April 1 to June 30, 2021 using selective medium for Enterococci. Multilocus sequence typing, antimicrobial susceptibility testing, and whole-genome sequencing were performed. A total of 164 isolates, including Enterococcus faecium (41 isolates), Enterococcus faecalis (80 isolates), Enterococcus raffinosus (11 isolates), Enterococcus casseliflavus (nine isolates), Enterococcus avium (12 isolates), Enterococcus lactis (eight isolates), Enterococcus gallinarum (two isolates), and Enterococcus malodoratus (one isolate), were analyzed. We found one vanA-positive E. faecium, which was already informed when the patient was transferred to the hospital, nine vanC-positive E. casseliflavus, and two vanC-positive E. gallinarum. E. faecium isolates showed resistance to ampicillin (95.1%), imipenem (95.1%), and levofloxacin (87.8%), and E. faecalis isolates showed resistance to minocycline (49.4%). Ampicillin- and levofloxacin-resistant E. faecium had multiple mutations in penicillin-binding protein 5 (PBP5) (39/39 isolates) and ParC/GyrA (21/36 isolates), respectively. E. raffinosus showed resistance to ampicillin (81.8%), imipenem (45.5%), and levofloxacin (45.5%), and E. lactis showed resistance to ampicillin (37.5%) and imipenem (50.0%). The linezolid resistance genes optrA and cfr(B) were found only in one isolate of E. faecalis and E. raffinosus, respectively. This study, showing the status of enterococci infection in hospitalized patients, is one of the important information when considering nosocomial infection control of VRE.

Genomic epidemiology reveals multiple mechanisms of linezolid resistance in clinical enterococci in China

BACKGROUND

Infections caused by linezolid-resistant enterococci (LRE) are clinically difficult to treat and threaten patient health. However, there is a lack of studies on long time-span LRE strains in China. For this reason, our study comprehensively revealed the resistance mechanisms of LRE strains collected in a Chinese tertiary care hospital from 2011 to 2022.

METHODS

Enterococcal strains were screened and verified after retrospective analysis of microbial data. Subsequently, 65 LRE strains (61 Enterococcus faecalis and 4 Enterococcus faecium, MIC ≥ 8 µg/ml), 1 linezolid-intermediate Enterococcus faecium (MIC = 4 µg/ml) and 1 linezolid-susceptible Enterococcus faecium (MIC = 1.5 µg/ml) were submitted for whole-genome sequencing (WGS) analysis and bioinformatics analysis.

RESULTS

The optrA gene was found to be the most common linezolid resistance mechanism in our study. We identified the wild-type OptrA and various OptrA variants in 98.5% of LRE strains (61 Enterococcus faecalis and 3 Enterococcus faecium). We also found one linezolid-resistant Enterococcus faecium strain carried both optrA and cfr(D) gene, while one linezolid-resistant Enterococcus faecium only harbored the poxtA gene. Most optrA genes (55/64) were located on plasmids, with impB-fexA-optrA, impB-fexA-optrA-erm(A), fexA-optrA-erm(A), and fexA-optrA segments. A minority of optrA genes (9/64) were found on chromosomes with the Tn6674-like platform. Besides, other possible linezolid resistance-associated mechanisms (mutations in the rplC and rplD genes) were also found in 26 enterococcal strains.

CONCLUSIONS

Our study suggested that multiple mechanisms of linezolid resistance exist among clinical LRE strains in China.

Confronting antibiotic-resistant pathogens: Distinctive drug delivery potentials of progressive nanoparticles

Antimicrobial resistance arises over time, usually due to genetic modifications. Global observations of high resistance rates to popular antibiotics used to treat common bacterial diseases, such as diarrhea, STIs, sepsis, and urinary tract infections, indicate that our supply of effective antibiotics is running low. The mechanisms of action of several antibiotic groups are covered in this review. Antimicrobials disrupt the development and metabolism of bacteria, leading to their eventual death. However, in recent years, microorganisms become resistant to the drugs. Bacteria encode resistant genes against antibiotics and inhibit the function of antibiotics by reducing the uptake of drugs, modifying the enzyme's active site, synthesizing enzymes to degrade antibiotics, and changing the structure of ribosomal subunits. Additionally, the methods of action of resistant bacteria against different kinds of antibiotics as well as their modes of action are discussed. Besides, the resistant pathogenic bacteria which get the most priority by World Health Organisation (WHO) for synthesizing new drugs, have also been incorporated. To overcome antimicrobial resistance, nanomaterials are used to increase the efficacy of antimicrobial drugs. Metallic, inorganic, and polymer-based nanoparticles once conjugated with antibacterial drugs, exhibit synergistic effects by increasing the efficacy of the drugs by inhibiting bacterial growth. Nanomaterial's toxic properties are proportional to their concentrations. Higher concentration nanomaterials are more toxic to the cells. In this review, the toxic properties of nanomaterials on lung cells, lymph nodes, and neuronal cells are also summarized.

Urinary tract infection associated with bacteremia caused by vancomycin-resistant enterococcus following continent urinary diversion

Key Clinical Message

Even in a country where vancomycin-resistant enterococcus is rare, multidrug-resistant organism precautions are necessary when admitting patients with a history of medical exposure in other countries. On admission, screening is necessary and if infection is confirmed, a multidisciplinary approach involving different specialists is required.

Abstract

The patient was a 49-year-old Japanese female living in the United States. Total pelvic exenteration for cervical carcinoma, Miami pouch formation, and ileostomy had been performed in the United States. She returned to Japan to undergo postoperative adjuvant chemotherapy. Fever and abdominal pain occurred 42 days after surgery. She consulted the fever outpatient clinic, and a diagnosis of urinary retention-associated acute renal failure and pyelonephritis was made. We detected vancomycin-resistant enterococcus on urine/blood culture 5 days after admission. Infection control measures were implemented, and the ward was closed for 3 days. We administered linezolid, which was effective for pyelonephritis and bacteremia.

Factors affecting vancomycin-resistant Enterococcus faecium colonization of in-hospital patients in different wards

Objectives

The prevalence of vancomycin-resistant Enterococcus faecium (VRE) infection at a medical center in Eastern Taiwan rose to 80.6%, exceeding the average prevalence of 55.6% among all medical centers nationwide during the same period. In recent years, the number of cases of VRE infection detected among hospitalized patients has increased annually. However, most of these patients in different wards are asymptomatic carriers. Therefore, restricting active screening to high-risk units will not improve the current situation, and it is necessary to review the risk factors for VRE colonization to provide a reference for future infection control policies.

Materials and Methods

Between 2014 and 2019, there were 3188 VRE-positive cultures reported at our institution, as per the electronic medical records system.

Results

In the medical and surgical wards, patients who received penicillin (odds ratios [ORs]: 2.84 and 4.16, respectively) and third-generation cephalosporins (ORs: 3.17 and 6.19, respectively) were at higher risk of VRE colonization. In intensive care units, the use of carbapenems (OR: 2.08) was the most significant variable.

Conclusion

This study demonstrated that the risk factors for VRE colonization differed between wards. Thus, policies should be established according to the attributes of patients in each ward, and active screening tests should be performed according to individual risks, instead of a policy for comprehensive mass screening.

Fourier-transform infrared spectroscopy for typing of vancomycin-resistant Enterococcus faecium: performance analysis and outbreak investigation

Vancomycin-resistant Enterococci, mainly Enterococcus faecium (VREfm), are causing nosocomial infections and outbreaks. Bacterial typing methods are used to assist in outbreak investigations. Most of them, especially genotypic methods like multi-locus sequence typing (MLST), whole genome sequencing (WGS), or pulsed-field gel electrophoresis, are quite expensive and time-consuming. Fourier-transform infrared (FT-IR) spectroscopy assesses the biochemical composition of bacteria, such as carboxyl groups in polysaccharides. It is an affordable technique and has a faster turnaround time. Thus, the aim of this study was to evaluate FT-IR spectroscopy for VREfm outbreak investigations. Basic performance requirements like reproducibility and the effects of incubation time were assessed in distinct sample sets. After determining a FT-IR spectroscopy cut-off range, the clustering agreement between FT-IR and WGS within a retrospective (n: 92 isolates) and a prospective outbreak (n: 15 isolates) was investigated. For WGS an average nucleotide identity (ANI) cut-off score of 0.999 was used. Basic performance analysis showed reproducible results. Moreover, FT-IR spectroscopy readouts showed a high agreement with WGS-ANI analysis in clinical outbreak investigations (V-measure 0.772 for the retrospective and 1.000 for the prospective outbreak). FT-IR spectroscopy had a higher discriminatory power than MLST in the outbreak investigations. After determining cut-off values to achieve optimal resolution, FT-IR spectroscopy is a promising technique to assist in outbreak investigation as an affordable, easy-to-use tool with a turnaround time of less than one day. IMPORTANCE Vancomycin-resistant Enterococci, mainly Enterococcus faecium (VREfm), are a frequent cause of nosocomial outbreaks. Several bacterial typing methods are used to track transmissions and investigate outbreaks, whereby genome-based techniques are used as a gold standard. Current methods are either expensive, time-consuming, or both. Additionally, often, specifically trained staff needs to be available. This study provides insight into the use of Fourier-transform infrared (FT-IR) spectroscopy, an affordable, easy-to-use tool with a short turnaround time as a typing method for VREfm. By assessing clinical samples, this work demonstrates promising results for species discrimination and reproducibility. FT-IR spectrosopy shows a high level of agreement in the analysis of VREfm outbreaks in comparison with whole genome sequencing-based methods.

Diphenyl Ether Derivative Rhexocerins and Rhexocercosporins from the Endophytic Fungus Rhexocercosporidium sp. Dzf14 Active against Gram-Positive Bacteria with Multidrug-Resistance

Ten new diphenyl ether polyketides, including rhexocerins A-D (1-4) and rhexocercosporins A-F (5-10), together with three known congeners (11-13), were isolated from the endophytic fungus Rhexocercosporidium sp. Dzf14 obtained from Dioscorea zingiberensis. Their structures were elucidated by analysis of NMR and HRESIMS data, and their absolute configurations were determined by quantum chemical ECD calculations and X-ray crystallography. Compounds 1-4 featured an unprecedented tetracyclic carbon skeleton (6/7/5/6). Among them, compounds 1 and 5-9 showed antibacterial activities against methicillin-resistant S. aureus T144 and vancomycin-resistant E. faecalis 10.

Effectiveness of patient and staff cohorting to reduce the risk of vancomycin-resistant enterococcus (VRE) acquisition: a retrospective cohort study during a VRE outbreak in Japan

BACKGROUND

Patient and staff cohorting is part of a bundle approach in the response to multi-drug-resistant organisms, but its effectiveness is not fully clarified. This study compared the risks of acquiring vancomycin-resistant Enterococcus faecium (VREfm) at a hospital during a VREfm outbreak based on contact characteristics in order to better understand the effectiveness of cohorting.

METHODS

Exposure came from contact with patients with VREfm (infectors), including existing patients with VREfm and patients who acquired VREfm during the study period. Contact was defined as length of contact time, degree of sharing space, and care by the same nurses as those caring for infectors between January and March 2018. The outcome was VREfm acquisition as determined through monthly stool or rectal screening cultures. Incidence rates were calculated based on contact patterns, and incidence rate ratios (IRRs) were compared.

FINDINGS

Among 272 inpatients (4038 patient-days), 43 patients acquired VREfm with the same or similar pulsotype. Incidence rates were 8.45 per 1000 patient-days when susceptible inpatients were on the same ward as an infector but cared for by different nurses (reference), 16.96 when susceptible inpatients were on the same ward as an infector and cared for by the same nurses [IRR 2.01, 95% confidence interval (CI) 0.62-10.28], and 52.91 when susceptible inpatients shared a room with an infector (IRR 6.26, 95% CI 1.61-35.40).

CONCLUSION

Compared with susceptible inpatients in a different room from infectors and not being cared for by the same nurses, the risk of VREfm acquisition could be six times higher for susceptible inpatients who are in the same room as infectors, and could be double for susceptible inpatients cared for by the same nurses as infectors.

A molecular study regarding the spread of vanA vancomycin-resistant Enterococcus faecium in a tertiary hospital in China

OBJECTIVES

Vancomycin-resistant enterococci (VRE) are one of the most important bacterial causes of healthcare-associated infections (HAIs). In China, the detection rate of VRE Enterococcus faecium (VREfm) is low, although VREfm had a high prevalence in our hospitals between 2013-2015. In this study, we used molecular typing methods combined with epidemiological data to investigate the spread of VREfm in our hospital.

METHODS

The characteristics of E. faecium strains isolated from 89 patients with HAIs, including antibiotic susceptibility and virulence genes, were analyzed. This study analyzed 50 E. faecium strains isolated from 47 intensive care unit and Emergency ward patients using core genome Multilocus Sequence Typing and transposon typing. Epidemiological information about those patients was also analyzed.

RESULTS

Twenty-seven E. faecium isolates containing the vanA gene were identified as VREfm in 89 non-duplicate E. faecium isolates. The major clonal VREfm strains that persisted from 2013-2015 were CT1/ST78/PFGE cluster A that contained transposon type Ⅰ. The other CT4/ST363/PFGE cluster of VREfm strains also contained transposon type Ⅰ. Three patients acquired different clonal E. faecium strains during the hospital period, and the VREfm strain infected one patient.

CONCLUSIONS

In this study, we report the spread caused by vanA vancomycin-resistant E. faecium strains of different cluster types with the same type of transposon in a tertiary hospital. Our literature review revealed that this is the first report of the HAIs caused by ST363/CT4 VREfm strains.

Antimicrobial Resistance Monitoring of Water Environments: A Framework for Standardized Methods and Quality Control

Antimicrobial resistance (AMR) is a grand societal challenge with important dimensions in the water environment that contribute to its evolution and spread. Environmental monitoring could provide vital information for mitigating the spread of AMR; this includes assessing antibiotic resistance genes (ARGs) circulating among human populations, identifying key hotspots for evolution and dissemination of resistance, informing epidemiological and human health risk assessment models, and quantifying removal efficiencies by domestic wastewater infrastructure. However, standardized methods for monitoring AMR in the water environment will be vital to producing the comparable data sets needed to address such questions. Here we sought to establish scientific consensus on a framework for such standardization, evaluating the state of the science and practice of AMR monitoring of wastewater, recycled water, and surface water, through a literature review, survey, and workshop leveraging the expertise of academic, governmental, consulting, and water utility professionals.

Occurrence, detection and ecotoxicity studies of selected pharmaceuticals in aqueous ecosystems- a systematic appraisal

Pharmaceutical compounds (PCs) have globally emerged as a significant group of environmental contaminants due to the constant detection of their residues in the environment. The main scope of this review is to fill the void of information on the knowledge on the African occurrence of selected PCs in environmental matrices in comparison with those outside Africa and their respective toxic actions on both aquatic and non-aquatic biota through ecotoxicity bioassays. To achieve this objective, the study focused on commonly used and detected pharmaceutical drugs (residues). Based on the conducted literature survey, Africa has the highest levels of ciprofloxacin, sulfamethoxazole, lamivudine, acetaminophen, and diclofenac while Europe has the lowest of all these PC residues in her physical environments. For ecotoxicity bioassays, the few data available are mostly on individual groups of pharmaceuticals whereas there is sparsely available data on their combined forms.

A Data-Driven Framework for Identifying Intensive Care Unit Admissions Colonized With Multidrug-Resistant Organisms

Background

The rising prevalence of multi-drug resistant organisms (MDROs), such as Methicillin-resistant Staphylococcus aureus (MRSA), Vancomycin-resistant Enterococci (VRE), and Carbapenem-resistant Enterobacteriaceae (CRE), is an increasing concern in healthcare settings.

Materials and Methods

Leveraging data from electronic healthcare records and a unique MDRO universal screening program, we developed a data-driven modeling framework to predict MRSA, VRE, and CRE colonization upon intensive care unit (ICU) admission, and identified the associated socio-demographic and clinical factors using logistic regression (LR), random forest (RF), and XGBoost algorithms. We performed threshold optimization for converting predicted probabilities into binary predictions and identified the cut-off maximizing the sum of sensitivity and specificity.

Results

Four thousand six hundred seventy ICU admissions (3,958 patients) were examined. MDRO colonization rate was 17.59% (13.03% VRE, 1.45% CRE, and 7.47% MRSA). Our study achieved the following sensitivity and specificity values with the best performing models, respectively: 80% and 66% for VRE with LR, 73% and 77% for CRE with XGBoost, 76% and 59% for MRSA with RF, and 82% and 83% for MDRO (i.e., VRE or CRE or MRSA) with RF. Further, we identified several predictors of MDRO colonization, including long-term care facility stay, current diagnosis of skin/subcutaneous tissue or infectious/parasitic disease, and recent isolation precaution procedures before ICU admission.

Conclusion

Our data-driven modeling framework can be used as a clinical decision support tool for timely predictions, characterization and identification of high-risk patients, and selective and timely use of infection control measures in ICUs.

Disinfection of methicillin-resistant Staphylococcus aureus, vancomycin-resistant Enterococcus faecium and Acinetobacter baumannii using Klaran WD array system

Hospital-associated infections (HAIs) are a major burden in healthcare systems. In this study, UVC LEDs emitting radiation from 260 to 270 nm were evaluated for effectiveness in reducing methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus faecium and Acinetobacter baumannii. The array has four WD LEDs, each with 70 mW placed at 7 cm from test organisms. With 11.76 mJ cm⁻², the study obtained 99.99% reduction (log₁₀ reduction factor of 4) against MRSA and VRE. For A. baumannii, 9 mJ cm⁻² obtained 99.999% reduction (log₁₀ reduction factor of 5). These results present scientific evidence on how effective UVC LEDs can be used in the fight against HAIs.

Comparing approaches for modelling indirect contact transmission of infectious diseases

Mathematical models describing indirect contact transmission are an important component of infectious disease mitigation and risk assessment. A model that tracks microorganisms between compartments by coupled ordinary differential equations or a Markov chain is benchmarked against a mechanistic interpretation of the physical transfer of microorganisms from surfaces to fingers and subsequently to a susceptible person's facial mucosal membranes. The primary objective was to compare these models in their estimates of doses and changes in microorganism concentrations on hands and fomites over time. The abilities of the models to capture the impact of episodic events, such as hand hygiene, and of contact patterns were also explored. For both models, greater doses were estimated for the asymmetrical scenarios in which a more contaminated fomite was touched more often. Differing representations of hand hygiene in the Markov model did not notably impact estimated doses but affected pathogen concentration dynamics on hands. When using the Markov model, losses due to hand hygiene should be handled as separate events as opposed to time-averaging expected losses. The discrete event model demonstrated the effect of hand-to-mouth contact timing on the dose. Understanding how model design influences estimated doses is important for advancing models as reliable risk assessment tools.

Sex differences in vancomycin-resistant enterococci bloodstream infections-a systematic review and meta-analysis

Background

Vancomycin-resistant enterococci (VRE) have emerged in the healthcare setting worldwide. Infections with these pathogens, i.e., bloodstream infections (BSI), are accompanied with an impaired patient outcome. Diverse factors comprising patient characteristics, therapeutic strategies, and infection control measures are positively or negatively associated with VRE BSI occurrence. However, whether sex-specific differences influence the frequency of VRE BSI is yet unknown.

The aim of this systematic review was to comprehensively summarize and analyze sex prevalence in VRE BSI patients.

Main text

A systematic search for relevant articles was conducted in PubMed and Web of Science. After screening for eligibility, data extraction from included articles and risk of bias assessment were processed. The prevalence of male/female sex in VRE BSI patients and 95% CI were calculated for each study and summarized as pooled estimated effect.

In total, nine articles met the inclusion criteria. Risk of bias assessment resulted in low (six studies) to moderate bias (three studies). The pooled prevalence of male patients suffering from VRE BSI was 59% resulting in a 1.4 male/female prevalence ratio.

Conclusions

Current literature suggests sex differences with male preference (59%) in the distribution of VRE BSI cases. Further primary studies should address the question of male-specific factors favoring the enhanced frequency of VRE BSI.

Prevalence of vancomycin-resistant enterococci in Asia-A systematic review and meta-analysis

WHAT IS KNOWN AND OBJECTIVE

The rise of vancomycin-resistant enterococci (VRE) has been a major health problem in most countries of the world including Asia, since its discovery. There is a paucity of data on VRE in many countries of Asia as well as limited pooled estimates. Therefore, we performed a systematic review and meta-analysis to estimate a pooled prevalence of VRE in Asia.

METHODS

A literature search in electronic databases like PubMed, Embase and Google Scholar and manual searching of references and grey literature, comprising the information on the prevalence of VRE with at least two species of enterococci, conducted in different countries of Asia from January 1, 2000, to September 20, 2020, was done. The random-effect model and 95% CIs was used to calculate the pooled prevalence. Subgroup, sensitivity and meta-regression analyses were performed to address heterogeneity while Egger's test for publication bias.

RESULTS AND DISCUSSIONS

We identified 39 studies, comprising a total of 11,875 enterococcal isolates. The result of the analysis showed that the pooled prevalence of VRE in Asia was 8.10% (95% CI; 7-9; I²  = 93.79%; p < 0.001). Resistance to vancomycin was greater among strains of E. faecium compared to the strains of E. faecalis (22.40% vs. 3.70%). Amongst various regions of Asia, the highest prevalence of VRE was found in the Western Asian region and the lowest in the South-east Asian region. Moreover, the rate of VRE was higher than most European countries and lower than USA.

WHAT IS NEW AND CONCLUSIONS

With an upsurge of VRE in Asia in recent years, efficient infection control programmes, robust surveillance systems and adherence to antibiotic stewardship are paramount to halt the further rise of VRE.

Genome-Wide Mutagenesis Identifies Factors Involved in Enterococcus faecalis Vaginal Adherence and Persistence

Enterococcus faecalis is a Gram-positive commensal bacterium native to the gastrointestinal tract and an opportunistic pathogen of increasing clinical concern. E. faecalis also colonizes the female reproductive tract, and reports suggest vaginal colonization increases following antibiotic treatment or in patients with aerobic vaginitis. Currently, little is known about specific factors that promote E. faecalis vaginal colonization and subsequent infection. We modified an established mouse vaginal colonization model to explore E. faecalis vaginal carriage and demonstrate that both vancomycin-resistant and -sensitive strains colonize the murine vaginal tract. Following vaginal colonization, we observed E. faecalis in vaginal, cervical, and uterine tissue. A mutant lacking endocarditis- and biofilm-associated pili (Ebp) exhibited a decreased ability to associate with human vaginal and cervical cells in vitro but did not contribute to colonization in vivo Thus, we screened a low-complexity transposon (Tn) mutant library to identify novel genes important for E. faecalis colonization and persistence in the vaginal tract. This screen revealed 383 mutants that were underrepresented during vaginal colonization at 1, 5, and 8 days postinoculation compared to growth in culture medium. We confirmed that mutants deficient in ethanolamine catabolism or in the type VII secretion system were attenuated in persisting during vaginal colonization. These results reveal the complex nature of vaginal colonization and suggest that multiple factors contribute to E. faecalis persistence in the reproductive tract.

Association between hospital outbreaks and hand hygiene: Insights from electronic monitoring

BACKGROUND

Hand hygiene (HH) is an important patient safety measure linked to prevention of healthcare-associated infection yet how outbreaks affect HH performance has not been formally evaluated.

METHODS

A controlled interrupted time series was performed across five acute-care academic hospitals using group electronic monitoring. This system captures 100% of all hand sanitizer and soap dispenser activations via a wireless signal to a wireless hub divided by a previously validated estimate of the number of daily HH opportunities per patient bed multiplied by the hourly census of patients on the unit. Daily HH adherence 60 days prior and 90 days following outbreak on inpatient units was compared to control units not in outbreak over the same period, using a Poisson regression model adjusting for correlation within hospitals and units. Predictors of HH improvement were assessed in this multivariate model.

RESULTS

In the 60 days prior to outbreak, units destined for outbreak had significantly lower HH adherence compared to control units (IRR of 0.91 (95% CI 0.90-0.93; p <0.0001). Following outbreak, the HH adherence among outbreak units increased above controls (IRR 1.04, 95% CI = 1.02-1.06; p <0.0001). Greater improvements were noted for outbreaks on surgical units, involving antibiotic-resistant organisms and enteric outbreaks, as well as those where healthcare workers became ill.

CONCLUSIONS

Hospital outbreaks tend to occur on units with lower HH adherence and are associated with rapid improvements in HH performance. Group electronic monitoring of HH could be used to develop novel prospective feedback interventions designed to avert hospital outbreaks.

Programmable antibiotic delivery to combat methicillin-resistant Staphylococcus aureus through precision therapy

The rapid dissemination of life-threatening multidrug-resistant bacterial pathogens calls for the development of new antibacterial agents and alternative strategies. The virulence factor secreted by bacteria plays a crucial role in the sophisticated processes during infections. Inspired by the unique capacity of many bacteria inducing clotting of plasma to initiate colonization, we propose a programmable antibiotic delivery system for precision therapy using methicillin-resistant S. aureus (MRSA) as a model. Coagulase utilized by MRSA to directly cleave fibrinogen into fibrin, is an ideal target not only for tracking bacterial status but for triggering the collapse of fibrinogen functionalized porous microspheres. Subsequently, staphylokinase, another virulence factor of MRSA, catalyzed hydrolysis of fibrin to further release the encapsulated antibiotics from microspheres. Our sequential triggered-release system exhibits high selectivity to distinguish live or dead MRSA from other pathogenic bacteria. Furthermore, such programmable microspheres clear 99% MRSA in 4 h, and show increased efficiency in a wound healing model in rats. Our study provides a programmable drug delivery system to precisely target bacterial pathogens using their intrinsic enzymatic cascades. This programmable platform with reduced selective stress of antibiotics on microbiota sheds light on the potential therapy for future clinical applications.

Natural Flavones from Morus alba against Methicillin-Resistant Staphylococcus aureus via Targeting the Proton Motive Force and Membrane Permeability

The emergence and rapid spread of methicillin-resistant Staphylococcus aureus (MRSA) critically requires alternative therapeutic options. New antibacterial drugs and strategies are urgently needed to combat MRSA-associated infections. Here, we investigated the antibacterial activity of flavones from Morus alba and the potential mode of action against MRSA. Kuwanon G, kuwanon H, mulberrin, and morusin displayed high efficiency in killing diverse MRSA isolates. On the basis of structure-activity analysis, the cyclohexene-phenyl ketones and isopentenyl groups were critical to increase the membrane permeability and to dissipate the proton motive force. Meanwhile, mechanistic studies further showed that kuwanon G displayed rapid bactericidal activity in vitrowith difficulty in developing drug resistance. Kuwanon G targeted phosphatidylglycerol and cardiolipin in the cytoplasmic membrane through the formation of hydrogen bonds and electrostatic interactions. Additionally, kuwanon G promoted wound healing in a mouse model of MRSA skin infection. In summary, these results indicate that flavones are promising lead compounds to treat MRSA-associated infections through disrupting the proton motive force and membrane permeability.

The calcium-dependent lipopeptide antibiotics: structure, mechanism, & medicinal chemistry

To push back the growing tide of antibacterial resistance the discovery and development of new antibiotics is a must. In recent years the calcium-dependent lipopeptide antibiotics (CDAs) have emerged as a potential source of new antibacterial agents rich in structural and mechanistic diversity. All CDAs share a common lipidated cyclic peptide motif containing amino acid side chains that specifically chelate calcium. It is only in the calcium bound state that the CDAs achieve their potent antibacterial activities. Interestingly, despite their common structural features, the mechanisms by which different CDAs target bacteria can vary dramatically. This review provides both a historic context for the CDAs while also addressing the state of the art with regards to their discovery, optimization, and antibacterial mechanisms.

Comparative study of antimicrobial resistance and biofilm formation among Gram-positive uropathogens isolated from community-acquired urinary tract infections and catheter-associated urinary tract infections

Background: Gram-positive cocci have emerged to be an important cause of urinary tract infection (UTI) both in community-acquired UTI (Com-UTI) and catheter-associated urinary tract infection (CA-UTI). The objective of this study was to investigate the frequency of Gram-positive cocci urinary tract infections, their susceptibility patterns to commonly used antimicrobial agents and the biofilm forming property with respect to catheter-associated UTI and community-acquired UTI.

Methods: A total of 1,360 urine samples from indwelling catheter and 10,423 from mid-stream urine were obtained during a 6-month period and processed following standard microbiological guidelines. Biofilm formation was detected using congo red agar (CRA), tube method (TM) and tissue culture plate (TCP) method. Chi-square test and independent sample t-test were employed to calculate the significance. Statistical significance was set at P-value ≤0.05.

Results: The infection rate was significantly higher in CA-UTI as compared to Com-UTI (25% vs 18%, p=0.0001). Among 2,216 organisms isolated, 471 were Gram-positive cocci; 401 were obtained from Com-UTI while 70 were from CA-UTI. Enterococcus faecalis was the most common organism isolated from Com-UTI, while Staphylococcus aureus was commonest among CA-UTI. Multi-drug resistance, methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococci were also significantly higher in CA-UTI as compared to Com-UTI. Biofilm-forming property was significantly higher in CA-UTI than Com-UTI. The sensitivity of congo red agar method and tube method was 79% and 81.9% respectively and specificity was 98.5% each. Antimicrobial resistance was significantly higher in biofilm-formers as compared to non-formers.

Conclusion: Gram-positive bacteria are a significant cause of both CA-UTI and Com-UTI with Enterococcus faecalis and Staphylococcus aureus as common pathogen. Biofilm formation and multi-drug resistance is significantly higher in CA-UTI than Com-UTI. Routine surveillance of antimicrobial resistance and biofilm formation is necessary in all cases of UTI to ensure the proper management of patients.

Environmental fate of pharmaceutical compounds and antimicrobial-resistant bacteria in hospital effluents, and contributions to pollutant loads in the surface waters in Japan

Environmental fate of 58 pharmaceutical compounds (PhCs) grouped into 11 therapeutic classes in the three different waters, hospital effluent, sewage treatment plant (STP) and river water, was estimated by combination of their quantitative concentration analysis and evaluation of their extent of contribution as loading sources. At the same time, distribution of six classes of antimicrobial-resistant bacteria (AMRB) in the same water samples was estimated by screening of individual PhC-resistant microbes grown on each specific chromogenic medium. The results indicate that 48 PhCs were detected ranged from 1 ng/L (losartan carboxylic acid) to 228 μg/L (acetaminophen sulfate) in hospital effluent, and contribution of the pollution load derived from hospital effluent to STP influent was estimated as 0.1% to 15%. On the other hand, contribution of STP effluent to river water was high, 32% to 60% for antibacterials, antipertensives and X-ray contrast media. In the cases for AMRB, detected numbers of colonies of AMRB in hospital effluent ranged from 29 CFU/mL to 1805 CFU/mL, and the estimated contribution of the AMRB pollution load derived from hospital effluent to STP influent was as low as 0.1% (levofloxacin and olmesartan) to 5.1% (N-desmethyl tamoxifen). Although the contribution of STPs as loading sources of PhCs and AMRB in surface waters was large, ozonation as an advanced water treatment system effectively removed a wide range of both PhCs and AMRB in water samples. These results suggest the importance of reducing environmental pollutant loads (not only at STPs but also at medical facilities) before being discharged into the surface waters, to both conserve water and keep the water environment safe. To our knowledge, this is the first report to show the distribution and contribution of AMRB from hospital effluent to the surface waters.

Distribution of the optrA gene in Enterococcus isolates at a tertiary care hospital in China

OBJECTIVES

Linezolid-resistant Enterococcus have spread worldwide. This study investigated the prevalence of linezolid-non-susceptible Enterococcus (LNSE) and the potential mechanism and molecular epidemiology of LNSE isolates from Nanjing, China.

METHODS

Linezolid susceptibility of 2555 Enterococcus was retrospectively determined by Etest. Vancomycin and teicoplanin MICs were determined for LNSE by Etest. PCR and DNA sequencing were used to investigate the potential molecular mechanism. Clonal relatedness between LNSE isolates was analysed by MLST. WGS was also performed.

RESULTS

A total of 27 Enterococcus isolates (24 Enterococcus faecalis, 3 Enterococcus faecium) with linezolid MICs of 4-48μg/mL were identified, among which 20 E. faecalis and 3 E. faecium were positive for optrA. No mutations were found in genes encoding domain V of 23S rRNA or ribosomal proteins L3/L4; the cfr gene was not found. The 24 linezolid-non-susceptible E. faecalis were classified into eight STs (ST16, ST480, ST476, ST631, ST585, ST428, ST25 and ST689). The three linezolid-non-susceptible E. faecium were classified as ST17, ST400 and ST195. Comparison of the deduced OptrA amino acid sequences of the 23 optrA-positive isolates by PCR-based sequencing and WGS with that of the original OptrA from E. faecalis E349 revealed seven variants (KD, EDP, EDM, D, EDD, RDK and DP) in 16 isolates, with no mutations in the remaining 7 isolates. optrA was found downstream of fexA by searching the pE349 sequence based on WGS data.

CONCLUSIONS

Emergence of LNSE with optrA-mediated resistance and clonal dissemination of ST16 E. faecalis in our hospital may pose a potential public-health threat.

Nonribosomal antibacterial peptides that target multidrug-resistant bacteria

This review summarizes the development of nonribosomal antibacterial peptides from untapped sources that target multidrug-resistant bacteria.

Antimicrobial-resistant CC17 Enterococcus faecium: The past, the present and the future

Enterococcus faecium is a robust opportunistic pathogen that is most commonly found as a commensal of the human and animal gut but can also survive in the environment. Since the introduction and use of antimicrobials, E. faecium has been found to rapidly acquire resistance genes that, when expressed, can effectively circumvent the effects of most antimicrobials. The rapid acquisition of multiple antimicrobial resistances has led to the adaptation of specific E. faecium clones in the hospital environment, collectively known as clonal complex 17 (CC17). CC17 E. faecium are responsible for a significant proportion of hospital-associated infections, which can cause severe morbidity and mortality. Here we review the history of E. faecium from commensal to a significant hospital-associated pathogen, its robust phenotypic characteristics, commonly used laboratory typing schemes, and antimicrobial resistances with a focus on vancomycin and its associated mechanism of resistance. Finally, we review the global epidemiology of vancomycin-resistant E. faecium and potential solutions to problems faced in public health.

Hospital acquired vancomycin resistant enterococci in surgical intensive care patients - a prospective longitudinal study

Background

Vancomycin resistant enterococci (VRE) occur with enhanced frequency in hospitalised patients. This study elucidates the prevalence of VRE on admission among surgical intensive care unit (SICU) patients, whether these patients are at special risk for VRE acquisition and which risk factors support this process.

Methods

Patients admitted to SICUs of the University Hospital Münster were examined during August-October 2017. VRE screening was performed within 48 h after admission and directly prior to discharge of patients. In parallel risk factors were recorded to estimate their effect on VRE acquisition during SICU stay.

Results

In total, 374 patients (68% male) with a median age of 66 years were admitted to one of the SICUs during the investigation period. Of all, 336 patients (89.8%) were screened on admission and 268 (71.7%) on discharge. Nine patients were admitted with previously known VRE colonisation. Twelve (3.6%) further patients were VRE positive on admission. During ICU stay, eight (3.0%) additional patients turned out to be VRE colonised. Risk factors found to be significantly associated with VRE acquisition were median length of stay on the ICU (14 vs. 3 days; p = 0.01), long-term dialysis (12.5% vs. 2.0% of patients; p = 0.05), and antibiotic treatment with flucloxacillin (28.6% vs. 7.2% of patients; p = 0.01) or piperacillin/tazobactam (57.1% vs. 26.6% of patients; p = 0.01).

Conclusions

SICU patients are not at special risk for VRE acquisition. Previous stay on a SICU should therefore not be considered as specific risk factor for VRE colonisation.

Vancomycin-Resistant Enterococci: A Review of Antimicrobial Resistance Mechanisms and Perspectives of Human and Animal Health

Vancomycin-resistant enterococci (VRE) are both of medical and public health importance associated with serious multidrug-resistant infections and persistent colonization. Enterococci are opportunistic environmental inhabitants with a remarkable adaptive capacity to evolve and transmit antimicrobial-resistant determinants. The VRE gene operons show distinct genetic variability and apparently continued evolution leading to a variety of antimicrobial resistance phenotypes and various environmental and livestock reservoirs for the most common van genes. Such complex diversity renders a number of important therapeutic options including "last resort antibiotics" ineffective and poses a particular challenge for clinical management. Enterococci resistance to glycopeptides and multidrug resistance warrants attention and continuous monitoring.

The Surgical Infection Society Revised Guidelines on the Management of Intra-Abdominal Infection

BACKGROUND

Previous evidence-based guidelines on the management of intra-abdominal infection (IAI) were published by the Surgical Infection Society (SIS) in 1992, 2002, and 2010. At the time the most recent guideline was released, the plan was to update the guideline every five years to ensure the timeliness and appropriateness of the recommendations.

METHODS

Based on the previous guidelines, the task force outlined a number of topics related to the treatment of patients with IAI and then developed key questions on these various topics. All questions were approached using general and specific literature searches, focusing on articles and other information published since 2008. These publications and additional materials published before 2008 were reviewed by the task force as a whole or by individual subgroups as to relevance to individual questions. Recommendations were developed by a process of iterative consensus, with all task force members voting to accept or reject each recommendation. Grading was based on the GRADE (Grades of Recommendation Assessment, Development, and Evaluation) system; the quality of the evidence was graded as high, moderate, or weak, and the strength of the recommendation was graded as strong or weak. Review of the document was performed by members of the SIS who were not on the task force. After responses were made to all critiques, the document was approved as an official guideline of the SIS by the Executive Council.

RESULTS

This guideline summarizes the current recommendations developed by the task force on the treatment of patients who have IAI. Evidence-based recommendations have been made regarding risk assessment in individual patients; source control; the timing, selection, and duration of antimicrobial therapy; and suggested approaches to patients who fail initial therapy. Additional recommendations related to the treatment of pediatric patients with IAI have been included.

SUMMARY

The current recommendations of the SIS regarding the treatment of patients with IAI are provided in this guideline.

Advances in Rapid Identification and Susceptibility Testing of Bacteria in the Clinical Microbiology Laboratory: Implications for Patient Care and Antimicrobial Stewardship Programs

Early availability of information on bacterial pathogens and their antimicrobial susceptibility is of key importance for the management of infectious diseases patients. Currently, using traditional approaches, it usually takes at least 48 hours for identification and susceptibility testing of bacterial pathogens. Therefore, the slowness of diagnostic procedures drives prolongation of empiric, potentially inappropriate, antibacterial therapies. Over the last couple of years, the improvement of available techniques (e.g. for susceptibility testing, DNA amplification assays), and introduction of novel technologies (e.g. MALDI-TOF) has fundamentally changed approaches towards pathogen identification and characterization. Importantly, these techniques offer increased diagnostic resolution while at the same time shorten the time-to-result, and are thus of obvious importance for antimicrobial stewardship. In this review, we will discuss recent advances in medical microbiology with special emphasis on the impact of novel techniques on antimicrobial stewardship programs.

Temporal trends and risk factors for healthcare-associated vancomycin-resistant enterococci in adults

BACKGROUND

Published data regarding temporal trends in vancomycin-resistant enterococci (VRE) prevalence within specific regions or healthcare systems are scarce.

AIM

To characterize temporal trends and risk factors for healthcare-associated infections caused by VRE.

METHODS

The study included all adult discharges occurring from 2006 to 2014 with an enterococcal infection from three hospitals in a large academic healthcare system. Bivariate analyses were used to identify statistically significant factors associated with vancomycin-susceptible or -resistant infection. Statistically significant variables were included in a final logistic regression model. Trends assessed whether the proportion of enterococcal infections resistant to vancomycin changed over time.

FINDINGS

The sample included 10,186 adults with first-time healthcare-associated enterococcal infection. Significant risk factors (P≤0.05) for VRE in the final logistic regression model included: tertiary 1 hospital, intensive care unit length of stay, higher Charlson Comorbidity Index, previous immunosuppressive or chemotherapeutic medications, previous hospitalization, renal failure, malignancy, longer length of stay prior to infection, taking an antibiotic prior to infection, being female, and having an infection in winter or spring. Between 2006 and 2014, the rate of resistance varied from 37.1 to 42.9% but there were no significant differences in the proportion resistant to vancomycin over time (P=0.36).

CONCLUSION

Research targeted at risk factors is important to decrease the amount of VRE infections.

Evaluation of Vancomycin-Resistant Enterococci (VRE)–Associated Morbidity Following Relaxation of VRE Screening and Isolation Precautions in a Tertiary Care Hospital

Objective

To determine whether relaxing vancomycin-resistant enterococci (VRE) precautions results in an increase in the incidence of invasive VRE infections over time.

Design

Retrospective analysis of a microbiology database before and after relaxation of VRE screening and isolation precautions.

Setting

Urban tertiary care teaching hospital in Montreal, Canada.

Participants.

All hospitalized and emergency room patients over a 13-year period from January 1, 2000, to March 31, 2013.

Methods

We assessed the results of all microbiology cultures for the presence of VRE as well as the results of all polymerase chain reaction assays forvanAandvanBduring the study period. Applying criteria for 4 clinical situations (bacteremia, definite infection, possible infection, and colonization with VRE), we analyzed the effects of relaxed VRE screening and isolation precautions on the incidence of each of these outcomes over the time preceding and following this change.

Results

When VRE screening and isolation precautions were relaxed, a marked rise in VRE colonization was observed, with a lesser but definite rise in the 3 other outcomes. Despite this initial rise in all measures, all incidences other than colonization plateaued during the 34 months of follow-up.

Conclusions

Relaxation of VRE screening and isolation precautions was associated with an immediate increase in colonization and infection incidence. Despite increasing colonization, infection outcomes remained infrequent and stable, suggesting a finite number of susceptible hosts at risk. Relaxation of VRE protocols may not lead to increasing infection incidence in a hospital setting, advocating that cost effectiveness exercises, with targeted screening and isolation precautions, are crucial.

Vancomycin-Resistant Enterococcus (VRE) Transmission and Risk Factors in Contacts of VRE Carriers

During a 2-year period, the vancomycin-resistant enterococcus (VRE) acquisition rate was 10.9% (40/368) in patients who had shared a room with a newly detected VRE carrier. Exposure to vancomycin and to anti-anaerobic antibiotics were identified as independent risk factors for VRE acquisition. Sensitivity of the first rectal VRE screening was less than 50%.

Infect Control Hosp Epidemiol 2014;35(7):876–879

Results of Four-Year Rectal Vancomycin-Resistant Enterococci Surveillance in a Pediatric Hematology-Oncology Ward: From Colonization to Infection

Objective:

To investigate the clinical impact of vancomycin-resistant enterococci (VRE) colonization in patients with hematologic malignancies and associated risk factors.

Materials and Methods:

Patients colonized and infected with VRE were identified from an institutional surveillance database between January 2010 and December 2013. A retrospective case-control study was performed to identify the risk factors associated with development of VRE infection in VRE-colonized patients.

Results:

Fecal VRE colonization was documented in 72 of 229 children (31.4%). Seven VRE-colonized patients developed subsequent systemic VRE infection (9.7%). Types of VRE infections included bacteremia (n=5), urinary tract infection (n=1), and meningitis (n=1). Enterococcus faecium was isolated in all VRE infections. Multivariate analysis revealed severe neutropenia and previous bacteremia with another pathogen as independent risk factors for VRE infection development in colonized patients [odds ratio (OR): 35.4, confidence interval (CI): 1.7-72.3, p=0.02 and OR: 20.6, CI: 1.3-48.6, p=0.03, respectively]. No deaths attributable to VRE occurred.

Conclusion:

VRE colonization has important consequences in pediatric cancer patients.

Cadazolid Does Not Promote Intestinal Colonization of Vancomycin-Resistant Enterococci in Mice

The promotion of colonization with vancomycin-resistant enterococci (VRE) is one potential side effect during treatment of Clostridium difficile-associated diarrhea (CDAD), resulting from disturbances in gut microbiota. Cadazolid (CDZ) is an investigational antibiotic with potent in vitro activity against C. difficile and against VRE and is currently in clinical development for the treatment of CDAD. We report that CDZ treatment did not lead to intestinal VRE overgrowth in mice.

Comparison of Arbekacin and Vancomycin in Treatment of Chronic Suppurative Otitis Media by Methicillin Resistant Staphylococcus aureus

Methicillin-resistant Staphylococcus aureus (MRSA) is a major cause of ear infections. We attempted to evaluate the clinical usefulness of arbekacin in treating chronic suppurative otitis media (CSOM) by comparing its clinical efficacy and toxicity with those of vancomycin. Efficacy was classified according to bacterial elimination or bacteriologic failure and improved or failed clinical efficacy response. Ninety-five subjects were diagnosed with CSOM caused by MRSA. Twenty of these subjects were treated with arbekacin, and 36 with vancomycin. The bacteriological efficacy (bacterial elimination, arbekacin vs. vancomycin: 85.0% vs. 97.2%) and improved clinical efficacy (arbekacin vs. vancomycin; 90.0% vs. 97.2%) were not different between the two groups. However, the rate of complications was higher in the vancomycin group (33.3%) than in the arbekacin group (5.0%) (P=0.020). In addition, a total of 12 adverse reactions were observed in the vancomycin group; two for hepatotoxicity, one for nephrotoxicity, eight for leukopenia, two for skin rash, and one for drug fever. It is suggested that arbekacin be a good alternative drug to vancomycin in treatment of CSOM caused by MRSA.

Agriculture and food animals as a source of antimicrobial-resistant bacteria

One of the major breakthroughs in the history of medicine is undoubtedly the discovery of antibiotics. Their use in animal husbandry and veterinary medicine has resulted in healthier and more productive farm animals, ensuring the welfare and health of both animals and humans. Unfortunately, from the first use of penicillin, the resistance countdown started to tick. Nowadays, the infections caused by antibiotic-resistant bacteria are increasing, and resistance to antibiotics is probably the major public health problem. Antibiotic use in farm animals has been criticized for contributing to the emergence of resistance. The use and misuse of antibiotics in farm animal settings as growth promoters or as nonspecific means of infection prevention and treatment has boosted antibiotic consumption and resistance among bacteria in the animal habitat. This reservoir of resistance can be transmitted directly or indirectly to humans through food consumption and direct or indirect contact. Resistant bacteria can cause serious health effects directly or via the transmission of the antibiotic resistance traits to pathogens, causing illnesses that are difficult to treat and that therefore have higher morbidity and mortality rates. In addition, the selection and proliferation of antibiotic-resistant strains can be disseminated to the environment via animal waste, enhancing the resistance reservoir that exists in the environmental microbiome. In this review, an effort is made to highlight the various factors that contribute to the emergence of antibiotic resistance in farm animals and to provide some insights into possible solutions to this major health issue.

Vancomycin-resistance phenotypes, vancomycin-resistance genes, and resistance to antibiotics of enterococci isolated from food of animal origin

In the present study, 500 raw beef, pork, and chicken meat samples and 100 pooled egg samples were analyzed for the presence of vancomycin-resistant enterococci, vancomycin-resistance phenotypes, and resistance genes. Of 141 isolates of enterococci, 88 strains of Enterococcus faecium and 53 strains of E. faecalis were identified. The most prevalent species was E. faecium. Resistance to ampicillin (n = 93, 66%), ciprofloxacin (n = 74, 52.5%), erythromycin (n = 73, 51.8%), penicillin (n = 59, 41.8%) and tetracycline (n = 52, 36.9%) was observed, while 53.2% (n = 75) of the isolates were multiresistant and 15.6% (n = 22) were susceptible to all antibiotics. Resistance to vancomycin was exhibited in 34.1% (n = 30) of the E. faecium isolates (n = 88) and 1.9% (n = 1) of the E. faecalis isolates (n = 53) using the disc-diffusion test and the E-test. All isolates were tested for vanA and vanB using real-time polymerase chain reaction (PCR) and multiplex PCR, and for vanC, vanD, vanE, vanG genes using multiplex PCR only. Among E. faecalis isolates, no resistance genes were identified. Among the E. faecium isolates, 28 carried the vanA gene when tested by multiplex PCR and 29 when tested with real-time PCR. No isolate carrying the vanC, vanD, vanE, or vanG genes was identified. Melting-curve analysis of the positive real-time PCR E. faecium isolates showed that 22 isolates carried the vanA gene only, 2 isolates the vanB2,3 genes only, and seven isolates carried both the vanA and vanB2,3 genes. Enterococci should be considered a significant zoonotic pathogen and a possible reservoir of genes encoding resistance potentially transferred to other bacterial species.

Clinical and microbiological characteristics of vancomycin-resistant enterococci with the VanD phenotype and vanA genotype

Vancomycin-resistant enterococci (VRE) strains with the VanD phenotype and vanA genotype (VanD-vanA) have been reported in Asian countries. The VanD phenotype is characterized by low-level resistance to vancomycin and susceptibility or intermediate resistance to teicoplanin. We retrospectively determined the risk factors, clinical outcomes, and virulence factors for VanD-vanA VRE (20 patients colonized with Enterococcus faecium) compared to VanA-vanA VRE (20 patients colonized with E. faecium). Multiple VRE colonizations and recent glycopeptide use were related to the presence of the VanA phenotype. There were no significant differences between patients colonized with VanD-vanA VRE and VanA-vanA VRE for duration of hospital stay, duration of intensive care unit stay, or hospital mortality. The esp gene was identified from all enterococci, while 90% of VanD-vanA VRE isolates and 95% of VanA-vanA VRE isolates were positive for the hyl gene. VanA-vanA VRE was subsequently isolated from sequential samples in 8 of 20 patients (40%) with VanD-vanA VRE. All of these patients had received glycopeptides during the interval between sample collection, and 2 of 8 paired isolates (VanD-vanA VRE and VanA-vanA VRE) were closely related subtypes according to pulsed-field gel electrophoresis analysis. In conclusion, VanD-vanA VRE isolates might represent an unstable, heterogeneous population that can convert to the VanA phenotype after exposure to glycopeptides.

Infectious Diseases

Infectious disease agents include viruses, bacteria, fungi, protozoa, parasites, and proteins called prions. Some patients are asymptomatic from their infection, whereas in other patients, clinical or subclinical illness affects the patient during the perioperative period. Transmission of the agents can occur through airborne inhalation, through contact with contaminated body fluids, via food, through physical contact, or through vector organisms. Additionally, patient-patient and patient-healthcare worker (HCW) transmission of infectious diseases remain a high concern. The perioperative period represents a unique challenge in the prevention of transmission. While diligent hand washing remains a staple in the standard of care, other measures must be implemented with certain infectious agents. Several of the major infectious diseases will be reviewed in this section, and universal precautions will be examined. Careful perioperative planning and situational awareness should be practiced by the healthcare worker taking care of patients with transmissible diseases.