Economic and clinical impact of nosocomial meticillin-resistant Staphylococcus aureus infections in Singapore: a matched case–control study

Infection prevention and control in neonatal units: An ethnographic study of social and clinical interactions among healthcare providers and mothers in Ghana

INTRODUCTION

Healthcare-associated infections (HAIs) are a global health challenge, particularly in low- and middle-income countries (LMICs). Infection prevention and control (IPC) remains an important strategy for preventing HAIs and improving the quality of care in hospital wards. The social environment and interactions in hospital wards are important in the quest to improve IPC. This study explored care practices and the interactions between healthcare providers and mothers in the neonatal intensive care units (NICU) in two Ghanaian hospitals and discusses the relevance for IPC.

METHODOLOGY

This study draws on data from an ethnographic study using in-depth interviews, focus group discussions involving 43 healthcare providers and 72 mothers, and participant observations in the wards between September 2017 and June 2019. The qualitative data were analysed thematically using NVivo 12 to facilitate coding.

FINDINGS

Mothers of hospitalized babies faced various challenges in coping with the hospital environment. Mothers received sparse information about their babies' medical conditions and felt intimidated in the contact with providers. Mothers strategically positioned themselves as learners, guardians, and peers to enable them to navigate the clinical and social environment of the wards. Mothers feared that persistent requests for information might result in their being labelled "difficult mothers" or might impact the care provided to their babies. Healthcare providers also shifted between various positionings as professionals, caregivers, and gatekeepers, with the tendency to exercise power and maintain control over activities on the ward.

CONCLUSION

The socio-cultural environment of the wards, with the patterns of interaction and power, reduces priority to IPC as a form of care. Effective promotion and maintenance of hygiene practices require cooperation, and that healthcare providers and mothers find common grounds from which to leverage mutual support and respect, and through this enhance care for mothers and babies, and develop stronger motivation for promoting IPC.

Clinical Impact and Risk Factors of Intensive Care Unit-Acquired Nosocomial Infection: A Propensity Score-Matching Study from 2018 to 2020 in a Teaching Hospital in China

Purpose

Nosocomial infection (NI) is associated with poor prognosis. The present study assessed the clinical and microbiological characteristics of NI patients in the intensive care unit (ICU) and investigated the clinical impact and risk factors for NI in ICU patients.

Patients and Methods

An observational study was conducted in an adult general ICU. The electronic medical records of all patients admitted to the ICU for >2 days from 2018-2020 were analyzed retrospectively. Multivariate regression models were used to analyze the risk factors for NI in ICU patients. Propensity score-matching (PSM) was used to control the confounding factors between the case and control groups, thus analyzing the clinical impact of NIs.

Results

The present study included 2425 patient admissions, of which 231 (9.53%) had NI. Acinetobacter baumannii (33.0%) was the most common bacteria. Long-term immunosuppressive therapy, disturbance of consciousness, blood transfusion, multiple organ dysfunction syndromes (MODS), treatment with three or more antibiotics, mechanical ventilation (MV), tracheotomy, the urinary catheter (UC), nasogastric catheter, and central venous catheter (CVC) were risk factors for NI in the ICU patients. After PSM, patients with NI had a prolonged length of stay (LOS) in the ICU and hospital, significant hospitalization expenses (all p<0.001), increased mortality (p=0.027), and predicted mortality (p=0.007). The differences in the ICU and hospital LOSs among three pathogens were statistically significant (p<0.001); the results of the Escherichia coli infection group were lower than the other two pathogenic groups.

Conclusion

NI was associated with poor outcomes. The risk factors for NI identified in this study provided further insight into preventing NI.

Eleven-Year surveillance of methicillin-resistant Staphylococcus aureus infections at an Academic Health Centre

INTRODUCTION

Methicillin-resistant Staphylococcus aureus (MRSA) is an important human pathogen associated with nosocomial and community infections. There is a continual focus on the epidemiology of this public health threat owing to the increase in its spread and rapid development of resistance.

AIM

We aimed to demonstrate the time trend of antibiotic resistance by describing the epidemiology of MRSA infections at an academic health centre.

METHODOLOGY

We retrospectively reviewed cases during an 11-year period (from January 2009 to December 2019) with positive cultures for MRSA from various clinical sites in King Fahad Hospital of the University, to understand their clinical and microbiological profiles. Screening and colonisation samples were excluded.

RESULTS

A total of 1338 MRSA isolates were identified, with an increasing trend from 5.2% to 14.5% during 2009-2019. Skin and soft tissue samples were the most common source (52.4%) of MRSA infections. Vancomycin activity remained stable against MRSA, and only one isolate showed resistance to linezolid (< 1%). A significant reduction in susceptibility to clindamycin (p = 0.003), trimethoprim-sulfamethoxazole (p = 0.001), and rifampin (p < 0.0001) was detected over the study period.

CONCLUSIONS

MRSA infections still represent a significant burden on healthcare systems. Our data support the need for constant local and regional surveillance to devise relevant protocols to manage MRSA infections. Empirical therapy needs to consider the changing antimicrobial susceptibility trends among MRSA isolates.

Strengths and caveats of identifying resistance genes from whole genome sequencing data

INTRODUCTION

Antimicrobial resistance (AMR) continues to present major challenges to modern healthcare. Recent advances in whole-genome sequencing (WGS) have made the rapid molecular characterization of AMR a realistic possibility for diagnostic laboratories; yet major barriers to clinical implementation exist.

AREAS COVERED

We describe and compare short- and long-read sequencing platforms, typical components of bioinformatics pipelines, tools for AMR gene detection and the relative merits of read- or assembly-based approaches. The challenges of characterizing mobile genetic elements from genomic data are outlined, as well as the complexities inherent to the prediction of phenotypic resistance from WGS. Practical obstacles to implementation in diagnostic laboratories, the critical role of quality control and external quality assurance, as well as standardized reporting standards are also discussed. Future directions, such as the application of machine-learning and artificial intelligence algorithms, linked to clinically meaningful outcomes, may offer a new paradigm for the clinical application of AMR prediction.

EXPERT OPINION

AMR prediction from WGS data presents an exciting opportunity to advance our capacity to comprehensively characterize infectious pathogens in a rapid manner, ultimately aiming to improve patient outcomes. Collaborative efforts between clinicians, scientists, regulatory bodies and healthcare administrators will be critical to achieve the full promise of this approach.

Predictive Role of Targeted, Active Surveillance Cultures for Detection of Methicillin-Resistant Staphylococcus aureus

INTRODUCTION

Methicillin-resistant Staphylococcus aureus (MRSA) colonisation is an important source of healthcare-acquired infections. Reliable screening strategies for MRSA colonisation are essential for the timely implementation of infection control measures.

AIM

This study determined reliable MRSA screening sites to predict colonisation in resource-limited settings and estimated the impact of missed MRSA cases when shifting from multi- to single-site screening.

METHODOLOGY

A cross-sectional study was conducted in patients with positive MRSA surveillance cultures from the routinely screened sites (nasal, axillary, groin, and throat) from January 2009 to December 2019.

RESULTS

A total of 1906 screening tests were positive for MRSA cultures (n = 1345 patients). As a single site, the nasal cavity showed the highest MRSA detection, with a sensitivity of 66.8% (95% CI = 64-69) with 277.9 missed isolation days. Screening three or more anatomical sites detected 97-100% of MRSA cases, with 0-24.5 missed isolation days. Screening the axilla and groin separately or in combination showed a good clinical utility index (CUI) of >0.6 to <0.8, while an excellent CUI was obtained upon screening other site samples (>0.8). The combined nasal and throat cultures demonstrated a sensitivity of 93.2 (95% CI = 91-94) with 57.2 missed isolation days.

CONCLUSION

Multi-site screening is the optimal strategy for minimising MRSA exposure within a healthcare facility. For active MRSA surveillance, a combination of nasal and throat cultures can provide a practical approach in low-resource settings compared to nasal sampling alone.

Ward-level factors associated with methicillin-resistant Staphylococcus aureus acquisition-an electronic medical records study in Singapore

Background

Methicillin-Resistant Staphylococcus aureus (MRSA) is endemic in hospitals worldwide. Intrahospital transfers may impact MRSA acquisition risk experienced by patients. In this study, we investigated ward characteristics and connectivity that are associated with MRSA acquisition.

Methods

We analysed electronic medical records on patient transfers and MRSA screening of in-patients at an acute-care tertiary hospital in Singapore to investigate whether ward characteristics and connectivity within a network of in-patient wards were associated with MRSA acquisition rates over a period of four years.

Results

Most patient transfers concentrated in a stable core network of wards. Factors associated with increased rate of MRSA acquisition were MRSA prevalence among patients transferred from other wards (rate ratio (RR): 7.74 [95% confidence interval (CI): 3.88, 15.44], additional 5 percentage point), critical care ward (RR: 1.72 [95% CI: 1.09, 2.70]) and presence of MRSA cohorting beds (RR: 1.39 [95% CI: 1.03, 1.90]. Oncology ward (RR: 0.66 [95% CI: 0.46, 0.94]) (compared to medical ward), and median length of stay (RR: 0.70 [95% CI: 0.55, 0.90], additional 1.5 days) were associated with lower acquisition rates. In addition, we found evidence of interaction between MRSA prevalence among patients transferred from other wards and weighted in-degree although the latter was not associated with MRSA acquisition after controlling for confounders.

Conclusion

Wards with higher MRSA prevalence among patients transferred from other wards were more likely to have higher MRSA acquisition rate. Its effect further increased in wards receiving greater number of patients. In addition, critical care ward, presence of MRSA cohorting beds, ward specialty, and median length of stay were associated with MRSA acquisition.

Perspectives and practices of healthcare providers and caregivers on healthcare-associated infections in the neonatal intensive care units of two hospitals in Ghana

Healthcare-associated infections (HAIs) remain a serious threat to patient safety worldwide, particularly in low- and middle-income countries. Reducing the burden of HAIs through the observation and enforcement of infection prevention and control (IPC) practices remains a priority. Despite growing emphasis on HAI prevention in low- and middle-income countries, limited evidence is available to improve IPC practices to reduce HAIs. This study examined the perspectives of healthcare providers (HPs) and mothers in the neonatal intensive care unit on HAIs and determined the major barriers and facilitators to promoting standard IPC practices. This study draws on data from an ethnographic study using 38 in-depth interviews, four focus group discussions and participant observation conducted among HPs and mothers in neonatal intensive care units of a secondary- and tertiary-level hospital in Ghana. The qualitative data were analysed using a grounded theory approach, and NVivo 12 to facilitate coding. HPs and mothers demonstrated a modest level of understanding about HAIs. Personal, interpersonal, community, organizational and policy-level factors interacted in complex ways to influence IPC practices. HPs sometimes considered HAI concerns to be secondary in the face of a heavy clinical workload, a lack of structured systems and the quest to protect professional authority. The positive attitudes of some HPs, and peer interactions promoted standard IPC practices. Mothers expressed interest in participation in IPC activities. It however requires systematic efforts by HPs to partner with mothers in IPC. Training and capacity building of HPs, provision of adequate resources and improving communication between HPs and mothers were recommended to improve standard IPC practices. We conclude that there is a need for institutionalizing IPC policies and strengthening strategies that acknowledge and value mothers' roles as caregivers and partners in IPC. To ensure this, HPs should be better equipped to prioritize communication and collaboration with mothers to reduce the burden of HAIs.

The impact of healthcare associated infections on mortality and length of stay in Singapore-A time-varying analysis

OBJECTIVE

Methods that include the time-varying nature of healthcare-associated infections (HAIs) avoid biases when estimating increased risk of death and excess length of stay. We determined the excess mortality risk and length of stay associated with HAIs among inpatients in Singapore using a multistate model that accommodates the timing of key events.

DESIGN

Analysis of existing prospective cohort study data.

SETTING

Seven public acute-care hospitals in Singapore.

PATIENTS

Inpatients reviewed in a HAI point-prevalence survey (PPS) conducted between June 2015 and February 2016.

METHODS

We modeled each patient's admission over time using 4 states: susceptible with no HAI, infected, died, and discharged alive. We estimated the excess mortality risk and length of stay associated with HAIs, with adjustment for the baseline characteristics between the groups for mortality risk.

RESULTS

We included 4,428 patients, of whom 469 had ≥1 HAI. Using a multistate model, the expected excess length of stay due to any HAI was 1.68 days (95% confidence interval [CI], 1.15-2.21 days). Surgical site infections were associated with the longest excess length of stay of 4.68 days (95% CI, 2.60-6.76 days). After adjusting for baseline differences, HAIs were associated with increased hazards of in-hospital mortality (adjusted hazard ratio [aHR], 1.32; 95% CI, 1.09-1.65) and decreased hazards in being discharged (aHR, 0.75; 95% CI, 0.67-0.84).

CONCLUSIONS

HAIs are associated with increased length of hospital stay and mortality in hospitalized patients. Avoiding nosocomial infections can improve patient outcomes and free valuable bed days.

Antimicrobial Resistance in ESKAPE Pathogens

Antimicrobial-resistant ESKAPE ( Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species) pathogens represent a global threat to human health. The acquisition of antimicrobial resistance genes by ESKAPE pathogens has reduced the treatment options for serious infections, increased the burden of disease, and increased death rates due to treatment failure and requires a coordinated global response for antimicrobial resistance surveillance. This looming health threat has restimulated interest in the development of new antimicrobial therapies, has demanded the need for better patient care, and has facilitated heightened governance over stewardship practices.

Antimicrobial Resistance in ESKAPE Pathogens

Antimicrobial-resistant ESKAPE ( Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species) pathogens represent a global threat to human health. The acquisition of antimicrobial resistance genes by ESKAPE pathogens has reduced the treatment options for serious infections, increased the burden of disease, and increased death rates due to treatment failure and requires a coordinated global response for antimicrobial resistance surveillance. This looming health threat has restimulated interest in the development of new antimicrobial therapies, has demanded the need for better patient care, and has facilitated heightened governance over stewardship practices.

Criterion-Based Audit of Hand Hygiene Performance During Caesarean Section at a Referral Hospital in Northern Tanzania: An Uncontrolled Interventional Study

Background

Health-care-associated infection (HCAI) is a big challenge in both low- and high-income countries. Around childbirth, infection is among the main causes of maternal and perinatal morbidity and mortality. Appropriate hand hygiene practice is a simple and cost-effective way of reducing HCAIs. This study aimed to assess the baseline performance and knowledge of proper hand hygiene during caesarean sections and the impact of interventions guided by a criterion-based audit at a tertiary health facility in Tanzania.

Methods

A noncontrolled, before-and-after intervention study, guided by a criterion-based audit, was carried out. A criterion based checklist was used for direct observations of hand hygiene performance during cesarean section. A self-administered questionnaire was used to assess knowledge on infection prevention. Performance was compared before and after a half-way intervention.

Results

At baseline, low-quality hand hygiene performance was observed. Significant improvements of hand hygiene performance were observed for a number of criteria. Long nails: performance reduction from 15 (25%) to 3 (5%) (P=.04), polished nails: from 11 (18%) to 1 (2%) (P=.04), a score increase in hand wash with water from 43.8 (73%) to 60 (100%) (P=.001). Postoperatively, correct glove removal increased from 20 (33%) to 37.8 (66%) (P=.01). Alcohol-based hand rub use increased from 2 (3%) to 21 (35%) (P=.001). The number of health-care workers who did not wash hands after procedure with either water or alcohol-based hand rub reduced from 35 (58%) to 10 (17%) (P=.001). After the intervention, poor knowledge among health-care workers reduced from 7 (39%) to 3 (17%), while moderate knowledge increased from 8 (44%) to 12 (67%).

Conclusion

Feedback, discussion of findings, training, visual reminders, and distribution of alcohol-based hand rub, as part of a criterion-based audit is a powerful way of improving hand hygiene performance and knowledge in surgical wards.

The Use of Microbiome Restoration Therapeutics to Eliminate Intestinal Colonization With Multidrug-Resistant Organisms

Antibiotic resistance (AR) has been described by the World Health Organization as an increasingly serious threat to global public health. Many mechanisms of AR have become widespread due to global selective pressures such as widespread antibiotic use. The intestinal tract is an important reservoir for many multidrug-resistant organisms (MDROs), and next-generation sequencing has expanded understanding of the resistome, defined as the comprehensive sum of genetic determinants of AR. Intestinal decolonization has been explored as a strategy to eradicate MDROs with selective digestive tract decontamination and probiotics being notable examples with mixed results. This review focuses on fecal microbiota transplantation and the early evidence supporting its efficacy in decolonizing MDROs and potential mechanisms of action to reduce AR genes. Current evidence suggests that fecal microbiota transplantation may have promise in restoring healthy microbial diversity and reducing AR, and clinical trials are underway to better characterize its safety and efficacy.

Methicillin-resistant Staphylococcus aureus multiple sites surveillance: a systemic review of the literature

Purpose

The objective of this study was to evaluate the optimal number of sampling sites for detection of methicillin-resistant Staphylococcus aureus (MRSA) colonization.

Methods

We performed a Medline search from January 1966 to February 2014 for articles that reported the prevalence of MRSA at different body sites. Studies were characterized by study design, country and period of the study, number of patients and/or isolates of MRSA, specimen type, sites of MRSA isolation, study population sampled, diagnostic testing method, and percentage of the MRSA isolates at each site in relation to the total number of sites.

Results

We reviewed 3,211 abstracts and 177 manuscripts, of which 17 met the criteria for analysis (n=52,642 patients). MRSA colonization prevalence varied from 8% to 99% at different body sites. The nasal cavity as a single site had MRSA detection sensitivity of 68% (34%–91%). The throat and nares gave the highest detection rates as single sites. A combination of two swabs improved MRSA detection rates with the best combination being groin/throat (89.6%; 62.5%–100%). A combination of three swab sites improved MRSA detection rate to 94.2% (81%–100%) with the best combination being groin/nose/throat. Certain combinations were associated with low detection rates. MRSA detection rates also varied with different culture methods.

Conclusion

A combination of three swabs from different body sites resulted in the highest detection rate for MRSA colonization. The use of three swab sites would likely improve the recognition and treatment of MRSA colonization, which may in turn reduce infection and transmission of MRSA to other patients.

Influencing factors on hand hygiene behavior of nursing students based on theory of planned behavior: A descriptive survey study

BACKGROUND

Hand hygiene is the single most important measure to prevent transmission of infection, but the compliance rate of healthcare workers is relatively low.

OBJECTIVES

This study was conducted to identify the knowledge, beliefs, behavior, and affecting factors about hand hygiene among nursing students.

DESIGN

A descriptive survey study.

SETTINGS

The study was carried out in two South Korean nursing schools.

PARTICIPANTS

A total 208 nursing students participated in this study.

METHODS

Questionnaires were used to collect data.

RESULTS

The percentage of correct answers in the survey section concerning hand hygiene knowledge was 68.1%. No significant difference in the knowledge, behavioral beliefs, normative beliefs, or control beliefs data was found related to general characteristics. Behavioral beliefs correlated with normative beliefs (r=.25, p<.001) and hand hygiene behavior (r=.17, p=.017), and control beliefs correlated with hand hygiene behavior (r=.18, p=.010).

CONCLUSION

The results suggest that knowledge is not enough to change the beliefs related to hand hygiene; positive behavioral beliefs and strong control beliefs are also needed to increase hand hygiene compliance.

Length of stay an important mediator of hospital-acquired methicillin-resistant Staphylococcus aureus

Hospital-acquired methicillin-resistant Staphylococcus aureus (HA-MRSA) is becoming increasingly established in Asian hospitals. The primary aim of this study was to decompose the risk factors for HA-MRSA based on conceptual clinical pathways. The secondary aim was to show the amount of effect attributable to antibiotic exposure and total length of stay before outcome (LBO) so that institutions can manage at-risk patients accordingly. A case-control study consisting of 1200 inpatients was conducted in a large tertiary hospital in Singapore between January and December 2006. Results from the generalized structural equation model (GSEM) show that LBO [adjusted odds ratio (aOR) 14·9, 95% confidence interval (CI) 8·7-25·5], prior hospitalization (aOR 6·2, 95% CI 3·3-11·5), and cumulative antibiotic exposure (aOR 3·5, 95% CI 2·3-5·3), directly affected HA-MRSA acquisition. LBO accounted for the majority of the effects due to age (100%), immunosuppression (67%), and surgery (96%), and to a lesser extent for male gender (22%). Our model enabled us to account and quantify effects of intermediaries. LBO was found to be an important mediator of age, immunosuppression and surgery on MRSA infection. Traditional regression approaches will not only give different conclusions but also underestimate the effects. Hospitals should minimize the hospital stay when possible to reduce the risk of MRSA.

Review of a two-year methicillin-resistant Staphylococcus aureus screening program and cost-effectiveness analysis in Singapore

Background

Methicillin-resistant Staphylococcus aureus (MRSA) poses an increasingly large disease and economic burden worldwide. The effectiveness of screening programs in the tropics is poorly understood. The aims of this study are: (i) to analyze the factors affecting MRSA colonization at admission and acquisition during hospitalization and (ii) to evaluate the cost-effectiveness of a screening program which aims to control MRSA incidence during hospitalization.

Methods

We conducted a retrospective case–control study of patients admitted to the Communicable Disease Centre (CDC) in Singapore between Jan 2009 and Dec 2010 when there was an ongoing selective screening and isolation program. Risk factors contributing to MRSA colonization on admission and acquisition during hospital stay were evaluated using a logistic regression model. In addition, a cost-effectiveness analysis was conducted to determine the cost per disability-adjusted life year (DALY) averted due to implementing the screening and isolation program.

Results

The average prevalence rate of screened patients at admission and the average acquisition rate at discharge during the study period were 12.1 and 4.8 % respectively. Logistic regression models showed that older age (adjusted odds ratio (OR) 1.03, 95 % CI 1.02–1.04, p < 0.001) and dermatological conditions (adjusted OR 1.49, 95 % CI 1.11–1.20, p = 0.008) were independently associated with an increased risk of MRSA colonization at admission. Age (adjusted OR 1.02, 95 % CI 1.01–1.03, p = 0.002) and length of stay in hospital (adjusted OR 1.04, 95 % CI 1.03–1.06, p < 0.001) were independent factors associated with MRSA acquisition during hospitalization. The screening and isolation program reduced the acquisition rate by 1.6 % and was found to be cost saving. For the whole study period, the program cost US$129,916, while it offset hospitalization costs of US$103,869 and loss of productivity costs of US$50,453 with −400 $/DALY averted.

Discussion

This study is the first to our knowledge that evaluates the cost-effectiveness of screeningand isolation of MRSA patients in a tropical country. Another unique feature of the analysis is the evaluationof acquisition rates among specific types of patients (dermatological, HIV and infectious disease patients)and the comparison of the cost-effectiveness of screening and isolation between them.

Conclusions

Overall our results indicate high MRSA prevalence that can be cost effectively reduced by selective screening and isolation programs in Singapore.

Antiseptic Body Washes for Reducing the Transmission of Methicillin-Resistant Staphylococcus aureus: A Cluster Crossover Study

In a cluster cross-over trial, targeted decolonization with octenidine body washes was not associated with reduction in MRSA transmission or infection

Background. Limiting the spread of methicillin-resistant Staphylococcus aureus (MRSA) within healthcare facilities where the organism is highly endemic is a challenge. The use of topical antiseptic agents may help interrupt the transmission of MRSA and reduce the risk of clinical infection. Octenidine dihydrochloride is a topical antiseptic that exhibits in vitro efficacy against a wide variety of bacteria, including S aureus.

Methods. We conducted a prospective cluster crossover study to compare the use of daily octenidine body washes with soap and water in patients identified by active surveillance cultures to be MRSA-colonized, to prevent the acquisition of MRSA in patients with negative screening swabs. Five adult medical and surgical wards and 2 intensive care units were selected. The study involved an initial 6-month phase using octenidine or soap washes followed by a crossover in each ward to the alternative product. The primary and secondary outcomes were the rates of new MRSA acquisitions and MRSA clinical infections, respectively.

Results. A total of 10 936 patients admitted for ≥48 hours was included in the analysis. There was a small reduction in MRSA acquisition in the intervention group compared with controls (3.0% vs 3.3%), but this reduction was not significant (odds ratio, 0.89; 95% confidence interval, .72–1.11; P = .31). There were also no significant differences in clinical MRSA infection or incidence of MRSA bacteremia.

Conclusions. This study suggests that the targeted use of routine antiseptic washes may not in itself be adequate to reduce the transmission of MRSA in an endemic hospital setting.

Evolutionary dynamics of methicillin-resistant Staphylococcus aureus within a healthcare system

BACKGROUND

In the past decade, several countries have seen gradual replacement of endemic multi-resistant healthcare-associated methicillin-resistant Staphylococcus aureus (MRSA) with clones that are more susceptible to antibiotic treatment. One example is Singapore, where MRSA ST239, the dominant clone since molecular profiling of MRSA began in the mid-1980s, has been replaced by ST22 isolates belonging to EMRSA-15, a recently emerged pandemic lineage originating from Europe.

RESULTS

We investigated the population structure of MRSA in Singaporean hospitals spanning three decades, using whole genome sequencing. Applying Bayesian phylogenetic methods we report that prior to the introduction of ST22, the ST239 MRSA population in Singapore originated from multiple introductions from the surrounding region; it was frequently transferred within the healthcare system resulting in a heterogeneous hospital population. Following the introduction of ST22 around the beginning of the millennium, this clone spread rapidly through Singaporean hospitals, supplanting the endemic ST239 population. Coalescent analysis revealed that although the genetic diversity of ST239 initially decreased as ST22 became more dominant, from 2007 onwards the genetic diversity of ST239 began to increase once more, which was not associated with the emergence of a sub-clone of ST239. Comparative genomic analysis of the accessory genome of the extant ST239 population identified that the Arginine Catabolic Mobile Element arose multiple times, thereby introducing genes associated with enhanced skin colonization into this population.

CONCLUSIONS

Our results clearly demonstrate that, alongside clinical practice and antibiotic usage, competition between clones also has an important role in driving the evolution of nosocomial pathogen populations.

Strategic measures for the control of surging antimicrobial resistance in Hong Kong and mainland of China

Antimicrobial-resistant bacteria are either highly prevalent or increasing rapidly in Hong Kong and China. Treatment options for these bacteria are generally limited, less effective and more expensive. The emergence and dynamics of antimicrobial resistance genes in bacteria circulating between animals, the environment and humans are not entirely known. Nonetheless, selective pressure by antibiotics on the microbiomes of animal and human, and their associated environments (especially farms and healthcare institutions), sewage systems and soil are likely to confer survival advantages upon bacteria with antimicrobial-resistance genes, which may be further disseminated through plasmids or transposons with integrons. Therefore, antibiotic use must be tightly regulated to eliminate such selective pressure, including the illegalization of antibiotics as growth promoters in animal feed and regulation of antibiotic use in veterinary practice and human medicine. Heightened awareness of infection control measures to reduce the risk of acquiring resistant bacteria is essential, especially during antimicrobial use or institutionalization in healthcare facilities. The transmission cycle must be interrupted by proper hand hygiene, environmental cleaning, avoidance of undercooked or raw food and compliance with infection control measures by healthcare workers, visitors and patients, especially during treatment with antibiotics. In addition to these routine measures, proactive microbiological screening of hospitalized patients with risk factors for carrying resistant bacteria, including history of travel to endemic countries, transfer from other hospitals, and prolonged hospitalization; directly observed hand hygiene before oral intake of drugs, food and drinks; and targeted disinfection of high-touch or mutual-touch items, such as bed rails and bed curtains, are important. Transparency of surveillance data from each institute for public scrutiny provides an incentive for controlling antimicrobial resistance in healthcare settings at an administrative level.

In vitro photodynamic inactivation effects of Ru(II) complexes on clinical methicillin-resistant Staphylococcus aureus planktonic and biofilm cultures

Photosensitizers (PSs) combined with light are able to generate antimicrobial effects. Ru(II) complexes have been recognized as a novel class of PSs. In this study, we investigated the effectiveness of photodynamic inactivation (PDI) mediated by three Ru(II) polypyridine complexes, 1-3, against four isolates of clinical methicillin-resistant Staphylococcus aureus (MRSA-1, MRSA-2, MRSA-3 and MRSA-4). In PDI of a planktonic culture of MRSA-1, compound 3 showed the highest efficacy, likely owing to its advantageous light absorption, (1) O2 quantum yield and bacterial cellular binding. The PDI efficacy of 3 was further evaluated against all other strains and MRSA-1 biofilms. At appropriate PS concentrations, viability reduction of 100% or 96.83% was observed in planktonic or biofilm forms of MRSA, respectively. The mechanisms of action were investigated using negative staining transmission electron microscopy (TEM), confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM). It was demonstrated that PDI of planktonic bacteria was achieved primarily through damage to the cell envelope. Biofilms were eliminated through both the destruction of their structure and inactivation of the individual bacterial cells. In conclusion, Ru(II) complexes, especially 3, are potential candidates for the effective photodynamic control of MRSA infections.

Vancomycin versus daptomycin for the treatment of methicillin-resistant Staphylococcus aureus bacteremia due to isolates with high vancomycin minimum inhibitory concentrations: study protocol for a phase IIB randomized controlled trial

BACKGROUND

Vancomycin is the standard first-line treatment for methicillin-resistant Staphylococcus aureus bacteremia. However, recent consensus guidelines recommend that clinicians consider using alternative agents such as daptomycin when the vancomycin minimum inhibitory concentration is greater than 1 ug/ml. To date however, there have been no head-to-head randomized trials comparing the safety and efficacy of daptomycin and vancomycin in the treatment of such infections. The primary aim of our study is to compare the efficacy of daptomycin versus vancomycin in the treatment of bloodstream infections due to methicillin-resistant Staphylococcus aureus isolates with high vancomycin minimum inhibitory concentrations (greater than or equal to 1.5 ug/ml) in terms of reducing all-cause 60-day mortality.

METHODS/DESIGN

The study is designed as a multicenter prospective open label phase IIB pilot randomized controlled trial. Eligible participants will be inpatients over 21-years-old with a positive blood culture for methicillin-resistant Staphylococcus aureus with vancomycin minimum inhibitory concentration of greater than or equal to 1.5 ug/ml. Randomization into intervention or active control arms will be performed with a 1:1 allocation ratio. We aim to recruit 50 participants over a period of two years. Participants randomized to the active control arm will receive vancomycin dose-while those randomized to the intervention arm will receive daptomycin. Participants will receive a minimum of 14 days study treatment.The primary analysis will be conducted on the intention-to-treat principle. The Fisher's exact test will be used to compare the 60-day mortality rate from index blood cultures (primary endpoint) between the two treatment arms, and the exact two-sided 95% confidence interval will be calculated using the Clopper and Pearson method. Primary analysis will be conducted using a two sided alpha of 0.05.

DISCUSSION

If results from this pilot study suggest that daptomycin shows significant efficacy in the treatment of bloodstream infections due to methicillin-resistant Staphylococcus aureus isolates with high vancomycin minimum inhibitory concentrations, we aim to proceed with a larger scale confirmatory study. This would help guide clinicians and inform practice guidelines on the optimal treatment for such infections.

TRIAL REGISTRATION

The trial is listed on clinicaltrials.gov (NCT01975662, date of registration: 29 October 2013).

Progression from new methicillin-resistant Staphylococcus aureus colonisation to infection: an observational study in a hospital cohort

BACKGROUND

Patients newly colonised with methicillin-resistant Staphylococcus aureus (MRSA) are at higher risk of clinical MRSA infection. At present, there are limited data on the duration or magnitude of this risk in a hospital population with a known time of MRSA acquisition.

METHODS

A retrospective cohort study of 909 adult patients known to have newly identified MRSA colonisation during admission to National University Hospital, Singapore between 1 July 2007 and 30 June 2011 was undertaken. Patients were excluded if they had history of previous MRSA colonisation or infection, or if they had been a hospital inpatient in the preceding 12 months. Data were collected on the development of MRSA infection requiring hospitalisation up to 30 June 2012.

RESULTS

Of 840 patients newly colonised with MRSA as identified on active surveillance and not clinical specimens, 546 were men (65.0%) and the median age was 65 years (range 18-103 years). Median follow up was 24 months (range 0 -64 months, 85.1% followed >6 months). Clinical infection occurred in 121 patients (14.4%) with median time to infection of 22 days (95% CI 14-31). Overall 71.9% (87/121) of infected patients developed infection within 60 days of the date MRSA colonisation was detected. However, 17/121 patients (14.0%) developed clinical infection more than six months after documented MRSA acquisition. The most common sites of clinical infection were skin and soft tissue (49/121, 40.5%, 95% CI 31.7-49.8), respiratory tract (37/121, 30.6%, 95% CI 22.5-39.6) and bone and joint infections (14/121, 11.6%, 95% CI 6.5-18.7). Thirteen patients (13/121, 10.7%, 95% CI 5.8-17.7) had bacteraemias, of which six (5.0% 95% CI 1.8-10.5) were primary and seven (5.7%, 95% CI 2.3-11.6) were secondary to infection at other sites. Crude mortality at 30 days and six months was higher in patients with MRSA infection than colonisation alone (aOR 5.49, 95% CI 2.75-10.95, p<0.001 and aOR 2.94, 95% CI 1.78-4.85, p<0.001 respectively).

CONCLUSION

Risk of clinical infection is highest soon after MRSA acquisition. Prevention of MRSA acquisition in hospital will have significant impact on morbidity and mortality for patients.

Sustained meticillin-resistant Staphylococcus aureus control in a hyper-endemic tertiary acute care hospital with infrastructure challenges in Singapore

Background

Meticillin-resistant Staphylococcus aureus (MRSA) has been entrenched in Singapore hospitals since the 1980s, with an excess of 600 non-duplicate cases of infections (120 bacteraemia episodes) each year in our 995-bed university hospital. Approximately 5% of our hospital beds are used as isolation facilities.

Aim

To study the impact of an MRSA control bundle that was implemented via gradual geographic extension across hospital wards.

Methods

The bundle included active surveillance on admission and transfer/discharge to identify ward-based acquisition of MRSA, isolation and cohorting of MRSA-infected patients, enhanced hand hygiene initiatives, and publicly displayed feedback of MRSA acquisition and hand hygiene compliance rates. Implementation was between October 2006 and June 2010 in order to provide lead-time for the incremental development of infrastructural capacity, and to develop an ethic of infection prevention among staff. Results were analysed via interrupted time-series analysis.

Findings

MRSA infections fell midway through the implementation, with MRSA bacteraemia declining from 0.26 [95% confidence interval (CI): 0.18–0.34] cases per 1000 inpatient-days in the first quarter of 2004 to 0.11 (95% CI: 0.07–0.19) cases per 1000 inpatient-days in the first quarter of 2012. MRSA acquisition rates fell a year after the programme had been fully implemented, whereas hand hygiene compliance rose significantly from 47% (95% CI: 44–49) in the first quarter of 2009 to 69% (95% CI: 68–71) in the first quarter of 2012.

Conclusion

Successful staged implementation of an MRSA bundle in a hyper-endemic setting is sustainable and represents a model that may be adapted for similar settings.

The global spread of healthcare-associated multidrug-resistant bacteria: a perspective from Asia

Since antibiotics were first used, each new introduced class has been followed by a global wave of emergent resistance, largely originating in Europe and North America where they were first used. Methicillin-resistant Staphylococcus aureus spread from the United Kingdom and North America across Europe and then Asia over more than a decade. Vancomycin-resistant enterococci and Klebsiella pneumoniae carbapenemase-producing K. pneumoniae followed a similar path some 20 years later. Recently however, metallo-β-lactamases have originated in Asia. New Delhi metallo-β-lactamase-1 was found in almost every continent within a year of its emergence in India. Metallo-β-lactamase enzymes are encoded on highly transmissible plasmids that spread rapidly between bacteria, rather than relying on clonal proliferation. Global air travel may have helped facilitate rapid dissemination. As the antibiotic pipeline offers little in the short term, our most important tools against the spread of antibiotic resistant organisms are intensified infection control, surveillance, and antimicrobial stewardship.

Patients' views and experience of intravenous and oral antimicrobial therapy: room for change

Little is known about patients' views or preferences about the route of administration of antimicrobials. In this study semi-structured interviews were carried out to assess patients' perceptions of an infection that required IV antimicrobial therapy in hospital, their preference for intravenous, IV followed by oral and discharge on oral therapy or home IV therapy. Interviews were transcribed and the content analysed. Twelve patients were interviewed while in hospital or by telephone after discharge. Patients' information about their infection was incomplete and many expressed the view that they would like more information. Many patients expressed a preference for oral therapy over IV therapy although this was dependent on it being of equal efficacy. Contrary views were related to personal difficulty with tablets. Patients varied in their acceptance of home IV therapy and expressed concern about adequate support but the majority expressed a preference for being discharged on oral therapy once they were well enough.