Methicillin-resistant Staphylococcus aureus and vancomycin-resistant enterococcus: Recognition and prevention in intensive care units:

The prevalence and molecular epidemiology of vancomycin-resistant Enterococcus (VRE) carriage in patients admitted to intensive care units in Beijing, China

BACKGROUND

Vancomycin-resistant Enterococcus (VRE) can be carried in the gut for a long period and its carriage status is associated with subsequent infections. This study aimed to investigate the frequency of intestinal VRE carriage in intensive care patients in Beijing.

METHODS

A multicenter, retrospective cross-sectional study was conducted at six hospitals in Beijing, China. All patients admitted to intensive care units (ICUs) between April 2 and May 1, 2017, were enrolled, and their clinical data were gathered by reviewing electronic medical records. Rectal swabs collected from patients were stored at -80 °C in the Institute of Clinical Pharmacology, Peking University First Hospital, and they were selectively cultured for VRE, then the identified strains were analyzed by polymerase chain reaction (PCR) to detect the glycopeptide resistance gene and were characterized by multilocus sequence typing (MLST).

RESULTS

Of 148 patients recruited, 46 (31.1%) carried VRE, with the majority (n = 42) being Enterococcus faecium. In total, 78.3% of the VRE were vanA positive and 15.2% vanM positive, while 6.5% undetected glycopeptide resistance gene. The predominant ST was ST78 (47.6%) followed by ST192 (14.3%), ST555 (9.5%), and ST789 (9.5%). Multivariate analysis showed that factors associated VRE carriage were patients aged >65 years (odds ratio [OR], 3.786; 95% confidence interval [CI], 1.402-10.222) and recent third-generation cephalosporins use (OR, 6.360; 95% CI, 1.873-21.601).

CONCLUSIONS

The overall proportion of VRE carriage in patients admitted to ICUs was markedly high in Beijing, China. The vanM gene has been spread widely but vanA gene was the dominant resistance determinant in VRE in Beijing.

Isolation and identification of specific bacteriophages against methicillin-resistant Staphylococcus aureus, extended-spectrum beta-lactamases-producing Escherichia coli, extended-spectrum beta-lactamases-producing Klebsiella pneumoniae, and multidrug-resistant Acinetobacter baumanniiin vitro

Drug resistance of methicillin-resistant Staphylococcus aureus, extended-spectrum beta-lactamases-producing Escherichia coli and Klebsiella pneumoniae and multidrug-resistant Acinetobacter baumannii are also cited as one of the most important causes of community and hospital acquired infections. Phage therapy can be used as a therapeutic method for the treatment of infections caused by these bacteria. The aim of this study was to isolate bacteriophages from municipal wastewater and assess their effects against drug resistant bacterial strains. The single agar layer technique was used to investigate the bacteriolytic effect of bacteriophages. Then, the double agar layer technique was used to observe phage plaques and the transmission electron microscopy was used to study the morphology of the bacteriophages. Transparent plaque formation in a double agar layer test of methicillin-resistant S. aureus and extended-spectrum beta-lactamases-producing E. coli and K. pneumoniae indicated the lysis of bacterial cells by isolated bacteriophages. No bacteriophage against A. baumannii was isolated from municipal wastewater. The morphology of these bacteriophages was also identified by electron microscopy. The results of this study showed that bacteriophages act specifically and due to the increasing level of antibiotic resistance, phage therapy as a new treatment can open a new horizon for the treatment of multidrug resistant bacteria.

Focused review on dual inhibition of quorum sensing and efflux pumps: A potential way to combat multi drug resistant Staphylococcus aureus infections

Staphylococcus aureus is a common cause of skin infections, food poisoning and severe life-threatening infections. Methicillin-Resistant Staphylococcus aureus (MRSA) is known to cause chronic nosocomial infections by virtue of its multidrug resistance and biofilm formation mechanisms. The antimicrobial resistance owned by S. aureus is primarily due to efflux pumps and formation of microbial biofilms. These drug resistant, sessile and densely packed microbial communities possess various mechanisms including quorum sensing and drug efflux. Quorum sensing is a cooperative physiological process which is used by bacterial cells for social interaction and signal transduction in biofilm formation whereas efflux of drugs is derived by efflux pumps. Apart from their significant role in multidrug resistance, efflux pumps also contribute to transporting cell signalling molecules and due to their occurrence; we face the frightening possibility that we will enter the pre-antibiotic era soon. Compounds that modulate efflux pumps are also known as efflux pump inhibitors (EPI's) that act in a synergistic manner and potentiate the antibiotics efficacy which has been considered as a promising approach to encounter bacterial resistance. EPIs inhibit the mechanism of drug efflux s as well as transport of quorum sensing signalling molecules which are the supreme contributors of miscellaneous virulence factors. This review presents an accomplishments of the recent investigations allied to efflux pump inhibitors against S. aureus and also focus on related correspondence between quorum sensing system and efflux pump inhibitors in terms of S. aureus and MRSA biofilms that may open a new avenue for controlling MRSA infections.

The Direct Semi-Quantitative Detection of 18 Pathogens and Simultaneous Screening for Nine Resistance Genes in Clinical Urine Samples by a High-Throughput Multiplex Genetic Detection System

Background

Urinary tract infections (UTIs) are one the most common infections. The rapid and accurate identification of uropathogens, and the determination of antimicrobial susceptibility, are essential aspects of the management of UTIs. However, existing detection methods are associated with certain limitations. In this study, a new urinary tract infection high-throughput multiplex genetic detection system (UTI-HMGS) was developed for the semi-quantitative detection of 18 pathogens and the simultaneously screening of nine resistance genes directly from the clinical urine sample within 4 hours.

Methods

We designed and optimized a multiplex polymerase chain reaction (PCR) involving fluorescent dye-labeled specific primers to detect 18 pathogens and nine resistance genes. The specificity of the UTI-HMGS was tested using standard strains or plasmids for each gene target. The sensitivity of the UTI-HMGS assay was tested by the detection of serial tenfold dilutions of plasmids or simulated positive urine samples. We also collected clinical urine samples and used these to perform urine culture and antimicrobial susceptibility testing (AST). Finally, all urine samples were detected by UTI-HMGS and the results were compared with both urine culture and Sanger sequencing.

Results

UTI-HMGS showed high levels of sensitivity and specificity for the detection of uropathogens when compared with culture and sequencing. In addition, ten species of bacteria and three species of fungi were detected semi-quantitatively to allow accurate discrimination of significant bacteriuria and candiduria. The sensitivity of the UTI-HMGS for the all the target genes could reach 50 copies per reaction. In total, 531 urine samples were collected and analyzed by UTI-HMGS, which exhibited high levels of sensitivity and specificity for the detection of uropathogens and resistance genes when compared with Sanger sequencing. The results from UTI-HMGS showed that the detection rates of 15 pathogens were significantly higher (P<0.05) than that of the culture method. In addition, there were 41(7.72%, 41/531) urine samples were positive for difficult-to-culture pathogens, which were missed detected by routine culture method.

Conclusions

UTI-HMGS proved to be an efficient method for the direct semi-quantitative detection of 18 uropathogens and the simultaneously screening of nine antibiotic resistance genes in urine samples. The UTI-HMGS could represent an alternative method for the clinical detection and monitoring of antibiotic resistance.

The local hospital milieu and healthcare-associated vancomycin-resistant enterococcus acquisition

BACKGROUND

Vancomycin-resistant enterococcus (VRE) causes 4% of all healthcare-associated infections in the USA. The process by which the local hospital milieu contributes to VRE acquisition is not fully understood.

AIM

To determine the importance of specific factors within the local hospital environment for healthcare-associated VRE acquisition.

METHODS

This retrospective cohort study included patients admitted to six intensive care units at an academic medical centre from January 2012 to December 2016 with negative rectal VRE cultures on admission. VRE acquisition was defined as a positive surveillance swab performed at any time after the initial negative swab during the index hospitalization. The exposures of interest were VRE colonization pressure, VRE importation pressure, and use of vancomycin. Multivariable Cox proportional hazards modelling was performed, with patients followed until VRE acquisition, death, or for up to 30 days.

FINDINGS

Of 8485 patients who were initially VRE negative, 161 patients acquired VRE. On univariate analysis, patients with VRE acquisition were more likely to have received vancomycin, to have had a neighbouring patient who received vancomycin, to have high VRE importation pressure, or to have high VRE colonization pressure. On multivariable analysis, only high VRE colonization pressure was an independent predictor of VRE acquisition (adjusted hazard ratio: 1.79; 95% confidence interval: 1.19-2.70).

CONCLUSION

VRE colonization pressure was the most important risk factor for healthcare-associated VRE acquisition, regardless of VRE importation pressure. Interventions seeking to reduce VRE acquisition should focus on minimizing transmission between patients with known VRE and the local hospital environment.

Guidance on Frequency and Location of Environmental Sampling for Acinetobacter baumannii

We assessed various locations and frequency of environmental sampling to maximize information and maintain efficiency when sampling for Acinetobacter baumannii. Although sampling sites in closer proximity to the patient were more likely positive, to fully capture environmental contamination, we found value in sampling all sites and across multiple days. Infect Control Hosp Epidemiol 2018;39:339-342.

Emergence of Vancomycin-resistant Enterococci at a Teaching Hospital, Saudi Arabia

Background:

Vancomycin-resistant enterococci (VRE) are a major and emerging hospital-acquired pathogen associated with high mortality, particularly among the critically ill and Intensive Care Units (ICUs) patients. This study aimed to determine the prevalence and demographic and clinical characteristics of VRE among patients admitted to a university hospital in Riyadh, Saudi Arabia.

Methods:

A study was conducted during the period from September 2014 to November 2015 at King Khalid University Hospital, a tertiary care hospital in Riyadh, Saudi Arabia, including in-patients with VRE infection. Data were collected using laboratory results and the medical records of admitted patients and were analyzed using SPSS version 19.0 statistical software.

Results:

In a one-year period, 231 enterococci were isolated from blood, urine, exudates, sputum, stool, and body fluid. There were 191 (82.7%) vancomycin-sensitive enterococci (VSE) and 40 (17.3%) isolates were VRE. The Enterococcus species included E. faecalis 168 (72.7%), E. faecium, 53 (22.8%) E. gallinarum 5 (2.2%), and E. avium 5 (2.2%). VRE were more significant from blood specimens (P < 0.0001) while VSE were significantly more predominant from urine specimens (P < 0.0001). VRE were more commonly isolated from patients in ICUs and oncology unit (P = 0.0151 and P < 0.001, respectively) while VSE were more predominant in the medical and surgical areas (P = 0.0178 and P = 0.0178, respectively).

Conclusions:

This study highlights the high prevalence of VRE in the hospital and the association of enterococcal infections with high-risk areas and oncology units, which warrant more studies looking for better management of these infections.

The impact of infection by multidrug-resistant agents in patients with cirrhosis. A multicenter prospective study

BACKGROUND & AIMS

Bacterial strains resistant to antibiotics are a serious clinical challenge. We assessed the antibiotic susceptibility of bacteria isolated from infections in patients with cirrhosis by a multicentre investigation.

RESULTS

Three hundred and thirteen culture-positive infections (173 community acquired [CA] and 140 hospital acquired [HA]) were identified in 308 patients. Urinary tract infections, spontaneous bacterial peritonitis and bacteremias were the most frequent. Quinolone-resistant Gram-negative isolates were 48%, 44% were extended-spectrum beta-lactamase producers and 9% carbapenem resistant. In 83/313 culture-positive infections (27%), multidrug-resistant agents (MDRA) were isolated. This prevalence did not differ between CA and HA infections. MDRA were identified in 17 of 37 patients on quinolone prophylaxis, and in 46 of 166 not on prophylaxis (45% vs 27%; P<.03). In 287 cases an empiric antibiotic therapy was undertaken, in 37 (12.9%) this therapy failed. The in-hospital mortality rate of this subset of patients was significantly higher compared to patients who received an effective broad(er)-spectrum therapy (P=.038). During a 3-month follow-up, 56/203 culture-positive patients (27.6%) died, 24/63 who have had MDRA-related infections (38%) and 32/140 who have had antibiotic-susceptible infections (22.8%) (P=.025). Multivariate analysis disclosed MDRA infection, age, hepatocellular carcinoma, bilirubin, international normalized ratio and the occurrence of portal hypertension-related complications independent predictors of death.

CONCLUSIONS

Infection by MDRA is frequent in patients with cirrhosis and the prognosis is severe, especially in patients unresponsive to empiric antibiotic therapy.

Daily Bathing with Chlorhexidine and Its Effects on Nosocomial Infection Rates in Pediatric Oncology Patients

Infections remain a serious complication in pediatric oncology patients. To determine if daily bathing with Chlorhexidine gluconate can decrease the rate of nosocomial infection in pediatric oncology patients, we reviewed rates of infections in pediatric oncology patients over a 14-month span. Intervention group received daily bath with Chlorhexidine, while the control group did not receive daily bath. The results showed that daily bath with antiseptic chlorhexidine as daily prophylactic antiseptic topical wash leads to decreased infection density amongst the pediatric oncology patients, especially in patients older than 12 years of age. Furthermore, daily chlorhexidine bathing significantly reduced the rate of hospital acquired infection in patients older than 12 years of age. The findings of this study suggest that daily bathing with chlorhexidine may be an effective measure of reducing nosocomial infection in pediatric oncology 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.

A realist analysis of hospital patient safety in Wales: applied learning for alternative contexts from a multisite case study

Background

Hospital patient safety is a major social problem. In the UK, policy responses focus on the introduction of improvement programmes that seek to implement evidence-based clinical practices using the Model for Improvement, Plan-Do-Study-Act cycle. Empirical evidence that the outcomes of such programmes vary across hospitals demonstrates that the context of their implementation matters. However, the relationships between features of context and the implementation of safety programmes are both undertheorised and poorly understood in empirical terms.

Objectives

This study is designed to address gaps in conceptual, methodological and empirical knowledge about the influence of context on the local implementation of patient safety programmes.

Design

We used concepts from critical realism and institutional analysis to conduct a qualitative comparative-intensive case study involving 21 hospitals across all seven Welsh health boards. We focused on the local implementation of three focal interventions from the 1000 Lives+patient safety programme: Improving Leadership for Quality Improvement, Reducing Surgical Complications and Reducing Health-care Associated Infection. Our main sources of data were 160 semistructured interviews, observation and 1700 health policy and organisational documents. These data were analysed using the realist approaches of abstraction, abduction and retroduction.

Setting

Welsh Government and NHS Wales.

Participants

Interviews were conducted with 160 participants including government policy leads, health managers and professionals, partner agencies with strategic oversight of patient safety, advocacy groups and academics with expertise in patient safety.

Main outcome measures

Identification of the contextual factors pertinent to the local implementation of the 1000 Lives+patient safety programme in Welsh NHS hospitals.

Results

An innovative conceptual framework harnessing realist social theory and institutional theory was produced to address challenges identified within previous applications of realist inquiry in patient safety research. This involved the development and use of an explanatory intervention–context–mechanism–agency–outcome (I-CMAO) configuration to illustrate the processes behind implementation of a change programme. Our findings, illustrated by multiple nested I-CMAO configurations, show how local implementation of patient safety interventions are impacted and modified by particular aspects of context: specifically, isomorphism, by which an intervention becomes adapted to the environment in which it is implemented; institutional logics, the beliefs and values underpinning the intervention and its source, and their perceived legitimacy among different groups of health-care professionals; and the relational structure and power dynamics of the functional group, that is, those tasked with implementing the initiative. This dynamic interplay shapes and guides actions leading to the normalisation or the rejection of the patient safety programme.

Conclusions

Heightened awareness of the influence of context on the local implementation of patient safety programmes is required to inform the design of such interventions and to ensure their effective implementation and operationalisation in the day-to-day practice of health-care teams. Future work is required to elaborate our conceptual model and findings in similar settings where different interventions are introduced, and in different settings where similar innovations are implemented.

Funding

The National Institute for Health Research Health Services and Delivery Research programme.

Transdermal delivery of vancomycin hydrochloride using combination of nano-ethosomes and iontophoresis: in vitro and in vivo study

This study aimed to evaluate transdermal delivery of vancomycin hydrochloride using the combination of ethosomes as an encapsulating vesicle and iontophoresis. Ethosomes were prepared and evaluated in terms of electrochemical stability. Cathodal iontophoresis of negatively charged ethosomes and anodal iontophoresis of free drug solution and positively charged vesicles were conducted. The effect of current mode, density, concentration of drug and ionic strength was studied. In vivo study was performed by inducing mediastinitis in Sprague-Dawley rats using methicillin-resistant Staphylococcus aureus as infected pathogen, the mean bacterial count was compared between groups of rats, one of the treated groups received drug intramuscularly while the other group received vancomycin using iontophoretic delivery of optimized ethosomal formula. Ethosomes showed efficient electrochemical stability, cathodal iontophoresis of negatively charged vesicle (F2) showed maximum transdermal flux (550 µg/cm(2)/h) compared to free drug solution and other ethosomal formulae, transdermal flux was reduced by altering current mode from continuous to ON/OFF mode, reducing current density and by using normal saline as drug solvent; on the other hand, flux was potentiated by increasing drug concentration from 25 to 75 mg/ml. In vivo study revealed that there was a significant difference in terms of bacterial count between untreated and treated groups, while there was no statistically significant difference between the I.M. vancomycin treatment and treatment conducted by iontophoretic delivery of vancomycin encapsulated in ethosomal formula. Combination between ethosomes and iontophoresis had succeeded in delivering vancomycin transdermally.

Dendritic cells during Staphylococcus aureus infection: subsets and roles

Dendritic cells (DCs) are professional antigen-presenting cells (APCs) that play a crucial role in both innate and adaptive immune responses. DCs orient the immune responses by modulating the balance between protective immunity to pathogens and tolerance to self-antigens. Staphylococcus aureus (S. aureus) is a common member of human skin microbiota and can cause severe infections with significant morbidity and mortality. Protective immunity to pathogens by DCs is required for clearance of S. aureus. DCs sense the presence of the staphylococcal components using pattern recognition receptors (PRRs) and then orchestrate immune systems to resolve infections. This review summarizes the possible roles of DCs, in particular their Toll-like receptors (TLRs) involved in S. aureus infection and strategies by which the pathogen affects activation and function of DCs.

Horizontal infection control strategy decreases methicillin-resistant Staphylococcus aureus infection and eliminates bacteremia in a surgical ICU without active surveillance

OBJECTIVE

Methicillin-resistant Staphylococcus aureus infection is a significant contributor to morbidity and mortality in hospitalized patients worldwide. Numerous healthcare bodies in Europe and the United States have championed active surveillance per the "search and destroy" model. However, this strategy is associated with significant economic, logistical, and patient costs without any impact on other hospital-acquired pathogens. We evaluated whether horizontal infection control strategies could decrease the prevalence of methicillin-resistant S. aureus infection in the ICU, without the need for active surveillance.

DESIGN AND SETTING

Retrospective, observational study in the surgical ICU of a tertiary care medical center in Boston, MA, from 2005 to 2012.

PATIENTS

A total of 6,697 patients in the surgical ICU.

INTERVENTIONS

Evidence-based infection prevention strategies were implemented in an iterative fashion, including 1) hand hygiene program with refresher education campaign, 2) chlorhexidine oral hygiene program, 3) chlorhexidine bathing, 4) catheter-associated bloodstream infection program, and 5) daily goals sheets.

MEASUREMENTS AND MAIN RESULTS

The prevalence of methicillin-resistant S. aureus infection fell from 2.66 to 0.69 per 1,000 patient days from 2005 to 2012, an average decrease of 21% per year. The biggest decline in rate of infection was detected in 2008, which may suggest that the catheter-associated bloodstream infection prevention program was particularly effective. Among 4,478 surgical ICU admissions over the last 5 years, not a single case of methicillin-resistant S. aureus bacteremia was observed.

CONCLUSIONS

Aggressive multifaceted horizontal infection control is an effective strategy for reducing the prevalence of methicillin-resistant S. aureus infection and eliminating methicillin-resistant S. aureus bacteremia in the ICU without the need for active surveillance and decontamination.

Antibiotic use and emerging resistance: how can resource-limited countries turn the tide?

Antibiotic resistance is a global crisis driven by appropriate and inappropriate antibiotic use to treat human illness and promote animal growth. The antimicrobial resistance epidemic continues to spread due to the triple threat of unfettered access, minimal product regulation and oversight of antibiotic prescription, and lack of clinical diagnostic tools to support antibiotic de-escalation in low-resource settings. In high-resource settings, evidence-based strategies have improved the appropriateness of antibiotic use, limiting the spread of drug-resistant organisms and reducing hospital-associated infections, strategies which may also be effective to stop the spread of resistance in resource-poor countries. Current research and surveillance efforts on antimicrobial resistance and hospital-associated infections in low-resource settings are extremely limited and largely focused on intensive care units. Many challenges exist to improving antibiotic use and infection control in resource-limited settings, and turning the tide requires intensifying research and surveillance, antimicrobial stewardship, and developing new bedside diagnostic tools for bacterial infections and antimicrobial susceptibility.

To swab or not to swab? A prospective analysis of 341 SICU VRE screens

BACKGROUND

Vancomycin-resistant Enterococcus (VRE) screening is routine practice in many intensive care units despite the question of its clinical significance. The value of VRE screening at predicting subsequent VRE or other hospital-acquired infection (HAI) is unknown. The purpose of this investigation was to examine the rate of subsequent VRE HAI in patients undergoing VRE screening.

METHODS

This study was conducted in a 24-bed surgical intensive care unit (SICU) at a Level I trauma center. Patients admitted to the SICU between February and August 2011 who had rectal swab for VRE screening within 72 hours were followed prospectively for the development of VRE and other HAIs. Demographics, clinical characteristics, and infection rates were compared between VRE-positive and VRE-negative patients. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of VRE screening for predicting subsequent VRE HAI were calculated.

RESULTS

A total of 341 patients had VRE screening within 72 hours of SICU admission, with 32 VRE-positive (9%) and 309 VRE-negative (91%) patients. VRE-positive patients had a higher incidence of any HAI (78% vs. 35%, p < 0.001). Eight VRE-positive patients (25%) developed VRE HAI compared with only 3 VRE-negative patients (1%) (p < 0.001). VRE screening had a 73% sensitivity, 93% specificity, 25% PPV, and 99% NPV for determining subsequent VRE HAI.

CONCLUSION

VRE colonization was present in 9% of SICU patients at admission. Negative VRE screen result had a high specificity and NPV for the development of subsequent VRE HAI. Empiric treatment of VRE infection may be unnecessary in VRE-negative patients.

LEVEL OF EVIDENCE

Prognostic/epidemiologic study, level III. Therapeutic study, level IV.

The prevalence and significance of methicillin-resistant Staphylococcus aureus colonization at admission in the general ICU Setting: a meta-analysis of published studies

OBJECTIVE

To estimate the prevalence and significance of nasal methicillin-resistant Staphylococcus aureus colonization in the ICU and its predictive value for development of methicillin-resistant S. aureus infection.

DATA SOURCES

MEDLINE and EMBASE and reference lists of all eligible articles.

STUDY SELECTION

Studies providing raw data on nasal methicillin-resistant S. aureus colonization at ICU admission, published up to February 2013. Analyses were restricted in the general ICU setting. Medical, surgical, and interdisciplinary ICUs were eligible. ICU studies referring solely on highly specialized ICUs populations and reports on methicillin-resistant S. aureus outbreaks were excluded.

DATA EXTRACTION

Two authors independently assessed study eligibility and extrapolated data in a blinded fashion. The two outcomes of interest were the prevalence estimate of methicillin-resistant S. aureus nasal colonization at admission in the ICU and the sensitivity/specificity of colonization in predicting methicillin-resistant S. aureus-associated infections.

DATA SYNTHESIS

Meta-analysis, using a random-effect model, and meta-regression were performed. Pooled data extracted from 63,740 evaluable ICU patients provided an estimated prevalence of methicillin-resistant S. aureus nasal colonization at admission of 7.0% (95% CI, 5.8-8.3). Prevalence was higher for North American studies (8.9%; 95% CI, 7.1-10.7) and for patients screened using polymerase chain reaction (14.0%; 95% CI, 9.6-19). A significant per year increase in methicillin-resistant S. aureus colonization was also noted. In 17,738 evaluable patients, methicillin-resistant S. aureus infections (4.1%; 95% CI, 2.0-6.8) developed in 589 patients. The relative risk for colonized patients was 8.33 (95% CI, 3.61-19.20). Methicillin-resistant S. aureus nasal carriage had a high specificity (0.96; 95% CI, 0.90-0.98) but low sensitivity (0.32; 95% CI, 0.20-0.48) to predict methicillin-resistant S. aureus-associated infections, with corresponding positive and negative predictive values at 0.25 (95% CI, 0.11-0.39) and 0.97 (95% CI, 0.83-1.00), respectively.

CONCLUSIONS

Among ICU patients, 5.8-8.3% of patients are colonized by methicillin-resistant S. aureus at admission, with a significant upward trend. Methicillin-resistant S. aureus colonization is associated with a more than eight-fold increase in the risk of associated infections during ICU stay, and methicillin-resistant S. aureus infection develops in one fourth of patients who are colonized with methicillin-resistant S. aureus at admission to the ICU.

Modulation of Bacterial Multidrug Resistance Efflux Pumps of the Major Facilitator Superfamily

Bacterial infections pose a serious public health concern, especially when an infectious disease has a multidrug resistant causative agent. Such multidrug resistant bacteria can compromise the clinical utility of major chemotherapeutic antimicrobial agents. Drug and multidrug resistant bacteria harbor several distinct molecular mechanisms for resistance. Bacterial antimicrobial agent efflux pumps represent a major mechanism of clinical resistance. The major facilitator superfamily (MFS) is one of the largest groups of solute transporters to date and includes a significant number of bacterial drug and multidrug efflux pumps. We review recent work on the modulation of multidrug efflux pumps, paying special attention to those transporters belonging primarily to the MFS.

Trends and significance of VRE colonization in the ICU: a meta-analysis of published studies

Background

The burden and significance of vancomycin-resistant enterococci (VRE) colonization in the ICU is not clearly understood.

Methods

We searched PubMed and EMBASE up to May 2013 for studies reporting the prevalence of VRE upon admission to the ICU and performed a meta-analysis to assess rates and trends of VRE colonization. We calculated the prevalence of VRE on admission and the acquisition (colonization and/or infection) rates to estimate time trends and the impact of colonization on ensuing VRE infections.

Findings

Across 37 studies (62,959 patients at risk), the estimated prevalence of VRE on admission to the ICU was 8.8% (7.1-10.6). Estimates were more consistent when cultures were obtained within 24 hours from admission. The VRE acquisition rate was 8.8% (95% CI 6.9-11.0) across 26 evaluable studies (35,364 patients at risk). Across US studies, VRE acquisition rate was 10.2% (95% CI 7.7-13.0) and demonstrated significant decline in annual trends. We used the US estimate of colonization on admission [12.3% (10.5-14.3)] to evaluate the impact of VRE colonization on admission in overall VRE prevalence. We demonstrated that VRE colonization on admission is a major determinant of the overall VRE burden in the ICU. Importantly, among colonized patients (including admitted and/or acquired cases) the VRE infection rates vary widely from 0-45% (with the risk of VRE bacteremia being reported from 0-16%) and <2% among those without a proven colonization.

Conclusion

In summary, up to 10.6% of patients admitted in the ICU are colonized with VRE on admission and a similar percentage will acquire VRE during their ICU stay. Importantly, colonization on admission is a major determinant of VRE dynamics in the ICU and the risk of VRE-related infections is close related to colonization.

Effects of daily bathing with chlorhexidine and acquired infection of methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus: a meta-analysis

OBJECTIVE

Chlorhexidine gluconate (CHG) is a common and safe antimicrobial agent and has been used widely in hand hygiene and skin disinfection; however, whether daily bathing with CHG results in the reduced acquired infection of methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus (VRE) remains inconclusive.

METHODS

We did a meta-analysis searching PubMed, Embase and the Cochrane Central Register database for available studies. Primary outcomes were acquired infection of MRSA, VRE.

RESULTS

In all, twelve articles were available in this review. We found that daily application of chlorhexidine bathing would significantly low the acquired colonization of MRSA [incidence rate ratio (IRR) =0.58, 95% confidence interval (CI): 0.41-0.82] or VRE (IRR =0.51, 95% CI: 0.36-0.73). Remarkably, the using of CHG bathing would significantly reduce the MRSA infection (IRR =0.56, 95% CI: 0.37-0.85), MRSA ventilator associated pneumonia (VAP) (IRR =0.22, 95% CI: 0.07-0.64) and VRE infection (IRR =0.57, 95% CI: 0.33-0.97). No significant publication bias was found in this meta-analysis.

CONCLUSIONS

The application of CHG bathing would significantly decrease acquired infection of MRSA or VRE, which may be an important complementary intervention to barrier precautions.

Risk factors associated with vancomycin-resistant enterococcus in intensive care unit settings in saudi arabia

Background. Vancomycin-resistant enterococci (VRE) are significant nosocomial pathogens worldwide. There is one report about the epidemiology of VRE in Saudi Arabia. Objective. To determine the risk factors associated with VRE infection or colonization in intensive care unit (ICU) settings. Design. This is a descriptive, epidemiologic hospital-based case-control study of patients with VRE from February 2006 to March 2010 in ICU in a tertiary hospital in Saudi Arabia. Methods. Data were collected from hospital records of patients with VRE. The main outcome measure was the adjusted odds ratio estimates of potential risk factors for VRE. Results. Factors associated with VRE included ICU admission for multiorgan failure, chronic renal failure, prior use of antimicrobial agents in the past three months and before ICU admission, gastrointestinal oral contrast procedure, and hemodialysis. Being located in a high risk room (roommate of patients colonized or infected with VRE) was found to be protective. Conclusions. Factors associated with VRE acquisition are often complex and may be confounded by local variables.

Surveillance and management of multidrug-resistant microorganisms

Multidrug-resistant organisms are an established and growing worldwide public health problem and few therapeutic options remain available. The traditional antimicrobials (glycopeptides) for multidrug-resistant Gram-positive infections are declining in efficacy. New drugs that are presently available are linezolid, daptomicin and tigecycline, which have well-defined indications for severe infections, and talavancin, which is under Phase III trial for hospital-acquired pneumonia. Unfortunately the therapies available for multidrug-resistant Gram-negatives, including carbapenem-resistant Pseudomonas aeruginosa, Acinetobacter baumannii and Enterobacteriaceae, are limited to only colistin and tigecycline. Both of these drugs are still not registered for severe infections, such as hospital acquired pneumonia. Consequently, as confirmed by scientific evidence, a multidisciplinary approach is needed. Surveillance, infection control procedures, isolation and antimicrobial stewardship should be implemented to reduce multidrug-resistant organism diffusion.

Reanimación y prevención de las infecciones nosocomiales

Los servicios de reanimación deben organizar de forma minuciosa la prevención de infecciones en sus enfermos, ya que éstos suelen estar inmunodeprimidos, están sometidos a múltiples procedimientos invasivos realizados por un personal sanitario variado, a menudo en situaciones de urgencia y a cualquier hora del día o de la noche. Las principales infecciones que hay que tratar de prevenir son las neumonías bacterianas adquiridas asociadas a ventilación mecánica (NAVM), las infecciones relacionadas con catéteres intravasculares y las infecciones urinarias asociadas al sondeo vesical. La incidencia de estas infecciones ha disminuido en la mayoría de los servicios que realizan un control cifrado, sobre todo gracias a la implantación de programas de mejora de la calidad. Las técnicas de prevención son múltiples y deben aplicarse simultáneamente. Incluyen medidas globales, como las modalidades de prevención de la transmisión cruzada (higiene de las manos, sobre todo) o de uso de antibióticos, concebidas para reducir la presión de selección de bacterias resistentes a éstos, así como medidas específicas relativas a la colocación y uso de cada uno de los dispositivos invasivos. Numerosas técnicas han demostrado su eficacia en estudios de buen nivel metodológico (higiene de las manos, apósitos para catéteres, etc.), mientras que otras siguen siendo objeto de controversias, por lo que las recomendaciones nacionales e internacionales se actualizan regularmente de acuerdo con los nuevos datos científicos. Estas medidas, implantadas de manera razonada en el marco de programas de mejora de la calidad, permiten obtener tasas muy bajas de infecciones relacionadas con el uso de catéteres vasculares y resultados menos satisfactorios con las NAVM, que justifican la necesidad de proseguir la investigación en este campo.

Rianimazione e prevenzione delle infezioni nosocomiali

I servizi di rianimazione devono organizzare la prevenzione delle infezioni nei loro pazienti in modo minuzioso, in quanto i pazienti sono spesso immunodepressi e subiscono gesti invasivi molteplici, realizzati da personale differente, spesso in situazioni di urgenza e a qualsiasi ora del giorno o della notte. Le principali infezioni che bisogna tentare di prevenire sono le polmoniti batteriche acquisite sotto ventilazione meccanica (PAVM), le infezioni su cateteri intravascolari e le infezioni urinarie su catetere vescicale. L’incidenza di queste infezioni è diminuita nella maggior parte dei servizi che ne effettuano un monitoraggio su base numerica, in particolare nel quadro di programmi di miglioramento della qualità. Le tecniche di prevenzione sono molteplici e devono essere applicate simultaneamente. Esse riguardano delle misure globali, come le modalità di prevenzione della trasmissione crociata (igiene delle mani, in particolare) o di utilizzo degli antibiotici nella prospettiva di ridurre la pressione di selezione di batteri resistenti agli antibiotici, così come delle misure specifiche relative al posizionamento e all’utilizzo di ciascuno dei dispositivi invasivi. Numerose tecniche si sono dimostrate efficaci in studi di buon livello metodologico (igiene delle mani, medicazioni dei cateteri, ecc.) mentre altre sono ancora oggetto di controversie, portando a raccomandazioni nazionali e internazionali regolarmente aggiornate in funzione dei nuovi dati scientifici. Queste misure, implementate in modo ragionato nel quadro di programmi di miglioramento della qualità, consentono di ottenere dei tassi molto bassi per quanto riguarda le infezioni dei cateteri vascolari e dei risultati meno buoni per le PAVM, illustrando la necessità di proseguire la ricerca in questo settore.

A structured approach to documenting a search strategy for publication: a 12 step guideline for authors

AIM

This paper describes a structured approach for documenting a search strategy, prior to the scholarly critique and review of the retrieved literature.

BACKGROUND AND CONTEXT

There has been a shift in publication expectations when it comes to the presentation of a literature review, from the more traditional narrative review to a more systematic approach, following a specific framework.

METHODS

This paper presents a 12 step framework for documenting the search strategy prior to undertaking a critique and synthesis of the retrieved literature. The authors provide a worked example about potential sources of cross contamination including hospital bath basins and soap and water bathing.

DISCUSSION

An overview of the 12 step framework is presented. This includes step-by-step instructions on how to conduct and write a search strategy for a literature review. A number of resources available for creating reviews and critiquing reviews are referenced, but these are not exclusive.

CONCLUSION

Reviews can be an important and valuable contribution when undertaken well, providing the reader with evidence of a clear structure. This paper provides a 12 step framework that will be of benefit to students, educationalists, and researchers required to embark on a review.

Impact of antibiotic exposure patterns on selection of community-associated methicillin-resistant Staphylococcus aureus in hospital settings

Community-associated methicillin-resistant S. aureus (CA-MRSA) is increasingly common in hospitals, with potentially serious consequences. The aim of this study was to assess the impact of antibiotic prescription patterns on the selection of CA-MRSA within hospitals, in a context of competition with other circulating staphylococcal strains, including methicillin-sensitive (MSSA) and hospital-associated methicillin-resistant (HA-MRSA) strains. We developed a computerized agent-based model of S. aureus transmission in a hospital ward in which CA-MRSA, MSSA, and HA-MRSA strains may cocirculate. We investigated a wide range of antibiotic prescription patterns in both intensive care units (ICUs) and general wards, and we studied how differences in antibiotic exposure may explain observed variations in the success of CA-MRSA invasion in the hospitals of several European countries and of the United States. Model predictions underlined the influence of antibiotic prescription patterns on CA-MRSA spread in hospitals, especially in the ICU, where the endemic prevalence of CA-MRSA carriage can range from 3% to 20%, depending on the simulated prescription pattern. Large antibiotic exposure with drugs effective against MSSA but not MRSA was found to promote invasion by CA-MRSA. We also found that, should CA-MRSA acquire fluoroquinolone resistance, a major increase in CA-MRSA prevalence could ensue in hospitals worldwide. Controlling the spread of highly community-prevalent CA-MRSA within hospitals is a challenge. This study demonstrates that antibiotic exposure strategies could participate in this control. This is all the more important in wards such as ICUs, which may play the role of incubators, promoting CA-MRSA selection in hospitals.

Antimicrobial susceptibility of daptomycin and comparator agents tested against methicillin-resistant Staphylococcus aureus and vancomycin-resistant enterococci: trend analysis of a 6-year period in US medical centers (2005-2010)

We evaluated daptomycin activity trends against methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE; MIC, ≥8 μg/mL) in a 6-year period (2005-2010) following US regulatory release for clinical use. Consecutive, unique patient strains of clinical significance were collected in 32 US medical centers and susceptibility tested in a central laboratory against daptomycin and various comparator agents by reference broth microdilution methods. A total of 22 858 S. aureus (12 181 [53.3%] MRSA), 4312 Enterococcus faecalis (195 [4.5%] VRE), and 2462 Enterococcus faecium (1867 [75.8%] VRE) were evaluated. Daptomycin susceptibility rates were 99.94%, 99.98%, and 99.68% for S. aureus, E. faecalis, and E. faecium, respectively. Among MRSA (daptomycin MIC₅₀/₉₀, 0.25/0.5 μg/mL), only 13 (0.11%) daptomycin-non-susceptible (MIC, ≥ 2 μg/mL) isolates were observed with no MIC creep over the study interval. Daptomycin was very active against vancomycin-resistant E. faecalis (MIC₅₀/₉₀, 1/2 μg/mL) and E. faecium (MIC₅₀/₉₀, 2/2 μg/mL). Among VRE, only 4 daptomycin-non-susceptible isolates (all E. faecium) were detected. In conclusion, daptomycin demonstrated sustained activity against an extensive collection of clinical isolates of MRSA and VRE from numerous US medical centers over the last 6 monitored years.

Antimicrobial resistance in the intensive care unit: mechanisms, epidemiology, and management of specific resistant pathogens

Infections caused by drug-resistant and multidrug-resistant microbial pathogens pose tremendous challenges to health care systems, including challenges related to the diagnosis, treatment, and containment of these infections. These challenges are amplified in the intensive care unit (ICU), where pressures for selection and emergence of resistance and risks of transmission of resistant pathogens are highest, and where the threat of resistance drives selection of empiric antimicrobial regimens. This article reviews basic concepts of resistance to antibacterial agents including mechanisms and modes of transmission, and discusses management issues for the important drug-resistant pathogens found in the ICU.

Implications for vancomycin-resistant Enterococcus colonization associated with Clostridium difficile infections

BACKGROUND

Vancomycin-resistant Enterococcus (VRE) colonization of the gastrointestinal tract shares similar risk factors with Clostridium difficile infection. We sought to elucidate the prevalence and risk factors of VRE colonization associated with C difficile infection.

METHODS

All adult inpatients with C difficile infection from July 2006 to October 2006 were prospectively evaluated. All C difficile toxin-positive stool samples were screened for detection of VRE. Risk factors for VRE colonization were compared in patients with C difficile infection with and without VRE colonization.

RESULTS

Of the 158 cases of C difficile infection evaluated, 88 (55.7%) involved VRE colonization. Independent risk factors for VRE colonization were admission from long-term care facilities (P = .013), dementia (P = .017), and hospitalization in the previous 2 months (P = .014). No statistically significant difference between C difficile infection cases with and without VRE colonization in terms of previous receipt (within 1 month) of antibiotics, including metronidazole and vancomycin, was found on multivariate analysis. C difficile infection cases with VRE colonization had a higher prevalence of coinfection with methicillin-resistant Staphylococcus aureus (P = .002) and Acinetobacter spp (P = .006).

CONCLUSION

VRE colonization was associated with >50% of C difficile infection cases and with a higher rate of coinfection with multidrug-resistant pathogens. Given the high rate of C difficile infection associated with VRE colonization, active surveillance of VRE in patients with C difficile infection is reasonable in high-risk settings.

Infection control in the intensive care unit: progress and challenges in systems and accountability

Attention to the improvement of safety in healthcare lately has focused on healthcare-associated infections, including many that occur in the intensive care unit, such as catheter-related bloodstream infections and ventilator-associated pneumonias. Great strides have been made in decreasing the rates of intensive care unit hospital-acquired infections in the past decade. This is attributable to a number of factors, including standardization of care, technological advances, provider payment reform, and consumer activism. Teamwork and communication remain the most important facets in patient safety. The papers in this supplement examine the roles of human factors and process engineering, survey a spectrum of infection control and safety challenges encountered by critical care practitioners, and assess the future challenges for continued improvement in our systems of care.