Risk factors for ICU-acquired methicillin-resistant Staphylococcus aureus infections

Impact of the implementation of the Intelligent Antimicrobial System (iAMS) on clinical outcomes among patients with bacteraemia caused by methicillin-resistant Staphylococcus aureus

OBJECTIVES

This study aimed to investigate the clinical impact of the Intelligent Antimicrobial System (iAMS) on patients with bacteraemia due to methicillin-resistant (MRSA) and methicillin-susceptible Staphylococcus aureus (MSSA).

METHODS

A total of 1008 patients with suspected SA infection were enrolled before and after the implementation of iAMS. Among them, 252 with bacteraemia caused by SA, including 118 in the iAMS and 134 in the non-iAMS groups, were evaluated.

RESULTS

The iAMS group exhibited a 5.2% (from 55.2% to 50.0%; P = 0.96) increase in the 1-year survival rate. For patients with MRSA and MSSA compared to the non-iAMS group, the 1-year survival rate increased by 17.6% (from 70.9% to 53.3%; P = 0.41) and 7.0% (from 52.3% to 45.3%; P = 0.57), respectively, both surpassing the rate of the non-iAMS group. The iAMS intervention resulted in a higher long-term survival rate (from 70.9% to 52.3%; P = 0.984) for MRSA patients than for MSSA patients. MRSA patients experienced a reduced length of hospital stay (from 23.3% to 35.6%; P = 0.038), and the 45-day discharge rate increased by 20.4% (P = 0.064). Furthermore, the intervention resulted in a significant 97.3% relative decrease in near miss medication incidents reported by pharmacists (P = 0.013).

CONCLUSIONS

Implementation of iAMS platform improved long-term survival rates, discharge rates, hospitalization days, and medical cost (although no significant differences were observed) among patients with MRSA bacteraemia. Additionally, it demonstrated significant benefits in ensuring drug safety.

Point Prevalence Survey of Antimicrobial Use during the COVID-19 Pandemic among Different Hospitals in Pakistan: Findings and Implications

The COVID-19 pandemic has significantly influenced antimicrobial use in hospitals, raising concerns regarding increased antimicrobial resistance (AMR) through their overuse. The objective of this study was to assess patterns of antimicrobial prescribing during the current COVID-19 pandemic among hospitals in Pakistan, including the prevalence of COVID-19. A point prevalence survey (PPS) was performed among 11 different hospitals from November 2020 to January 2021. The study included all hospitalized patients receiving an antibiotic on the day of the PPS. The Global-PPS web-based application was used for data entry and analysis. Out of 1024 hospitalized patients, 662 (64.64%) received antimicrobials. The top three most common indications for antimicrobial use were pneumonia (13.3%), central nervous system infections (10.4%) and gastrointestinal indications (10.4%). Ceftriaxone (26.6%), metronidazole (9.7%) and vancomycin (7.9%) were the top three most commonly prescribed antimicrobials among surveyed patients, with the majority of antibiotics administered empirically (97.9%). Most antimicrobials for surgical prophylaxis were given for more than one day, which is a concern. Overall, a high percentage of antimicrobial use, including broad-spectrums, was seen among the different hospitals in Pakistan during the current COVID-19 pandemic. Multifaceted interventions are needed to enhance rational antimicrobial prescribing including limiting their prescribing post-operatively for surgical prophylaxis.

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.

Empiric Treatment in HAP/VAP: “Don’t You Want to Take a Leap of Faith?”

Ventilator-associated pneumonia is a frequent cause of ICU-acquired infections. These infections are associated with high morbidity and mortality. The increase in antibiotic resistance, particularly among Gram-negative bacilli, makes the choice of empiric antibiotic therapy complex for physicians. Multidrug-resistant organisms (MDROs) related infections are associated with a high risk of initial therapeutic inadequacy. It is, therefore, necessary to quickly identify the bacterial species involved and their susceptibility to antibiotics. New diagnostic tools have recently been commercialized to assist in the management of these infections. Moreover, the recent enrichment of the therapeutic arsenal effective on Gram-negative bacilli raises the question of their place in the therapeutic management of these infections. Most national and international guidelines recommend limiting their use to microbiologically documented infections. However, many clinical situations and, in particular, the knowledge of digestive or respiratory carriage by MDROs should lead to the discussion of the use of these new molecules, especially the new combinations with beta-lactamase inhibitors in empirical therapy. In this review, we present the current epidemiological data, particularly in terms of MDRO, as well as the clinical and microbiological elements that may be taken into account in the discussion of empirical antibiotic therapy for patients managed for ventilator-associated pneumonia.

Evaluation of MRSA surveillance nasal swabs for predicting MRSA infection in SICU patients

BACKGROUND

We aimed to examine the clinical value of serial MRSA surveillance cultures to rule out a MRSA diagnosis on subsequent cultures during a patient's surgical intensive care unit (SICU) admission.

MATERIAL AND METHODS

We performed a retrospective cohort study to evaluate patients who received a MRSA surveillance culture at admission to the SICU (n = 6,915) and collected and assessed all patient cultures for MRSA positivity during their admission. The primary objective was to evaluate the transition from a MRSA negative surveillance on admission to MRSA positive on any subsequent culture during a patient's SICU stay. Percent of MRSA positive cultures by type following MRSA negative surveillance cultures was further analyzed.

MEASUREMENTS AND MAIN RESULTS

6,303 patients received MRSA nasal surveillance cultures at admission with 21,597 clinical cultures and 7,269 MRSA surveillance cultures. Of the 6,163 patients with an initial negative, 53 patients (0.87%) transitioned to MRSA positive. Of the 139 patients with an initial positive, 30 (21.6%) had subsequent MRSA positive cultures. Individuals who had an initial MRSA surveillance positive status on admission predicted MRSA positivity rates for cultures in qualitative lower respiratory cultures (64.3% versus. 3.1%), superficial wound (60.0% versus 1.6%), deep wound (39.0% versus 0.8%), tissue culture (26.3% versus 0.6%), and body fluid (20.8% versus 0.7%) cultures when compared to MRSA negative patients on admission.

CONCLUSION

Following MRSA negative nasal surveillance cultures patients showed low likelihood of MRSA infection suggesting empiric anti-MRSA treatment is unnecessary for specific patient populations. SICU patient's MRSA status at admission should guide empiric anti-MRSA therapy.

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.

Antimicrobial resistance and COVID-19: Intersections and implications

Before the coronavirus 2019 (COVID-19) pandemic began, antimicrobial resistance (AMR) was among the top priorities for global public health. Already a complex challenge, AMR now needs to be addressed in a changing healthcare landscape. Here, we analyse how changes due to COVID-19 in terms of antimicrobial usage, infection prevention, and health systems affect the emergence, transmission, and burden of AMR. Increased hand hygiene, decreased international travel, and decreased elective hospital procedures may reduce AMR pathogen selection and spread in the short term. However, the opposite effects may be seen if antibiotics are more widely used as standard healthcare pathways break down. Over 6 months into the COVID-19 pandemic, the dynamics of AMR remain uncertain. We call for the AMR community to keep a global perspective while designing finely tuned surveillance and research to continue to improve our preparedness and response to these intersecting public health challenges.

Analysis of Pathogen Distribution and Its Antimicrobial Resistance in Bloodstream Infections in Hospitalized Children in East China, 2015-2018

This study analyzed the pathogen distribution in bloodstream-infected (BSI) children hospitalized in Shandong Province from 2015 to 2018, to identify prevention strategies and select empiric antimicrobial therapy for BSI in children. Blood sample data from 14 107 children from 162 hospitals of Shandong Province were obtained from the China Antimicrobial Resistance Surveillance System and analyzed with WHONET 5.6 software. The results of the blood culture test showed the growth of 70.6% Gram-positive and 29.4% Gram-negative bacteria. Of the 14 107 blood isolates, 59.3% were collected from males and 40.7% were from females. Coagulase-negative staphylococci (47.1%) were the most commonly distributed pathogens. The distribution of pathogens varied according to age group and season. All Staphylococcus isolates were susceptible to vancomycin, teicoplanin and linezolid. Clinically, significant declines in penicillin-resistant Streptococcus pneumonia and carbapenem-resistant Escherichia coli were observed during the study period; however, detection rates of carbapenem-resistant Klebsiella pneumoniae increased over time (p < 0.05). Empiric antimicrobial therapy should be prescribed according to corresponding regional pediatric antimicrobial-resistant data.

Epidemiology of Bloodstream Infections in Hospitalized Children in the United States, 2009-2016

BACKGROUND

Bloodstream infections (BSIs) cause significant morbidity and mortality in children. Recent pediatric epidemiological data may inform prevention strategies and empiric antimicrobial therapy selection.

METHODS

We conducted a retrospective cohort study from 2009 through 2016 utilizing demographic and microbiologic data on inpatients aged <19 years using the Premier Healthcare Database. BSIs were positive blood cultures without known contaminants. Hospitalization rate was the number of BSI-positive encounters per 1000 admissions. Community-acquired infections (CAIs) were cultures positive ≤2 days of admission among nonneonates. BSI patients were compared to documented positive BSI patients (non-BSI); differences were analyzed using χ2 test, t test, and Cochran-Armitage test for time trends.

RESULTS

Among 1 809 751 encounters from 162 US hospitals, 5340 (0.30%) were BSI positive; CAIs were most common (50%). BSI patients were more often aged 1-5 years and had complex chronic conditions or central lines compared to non-BSI patients. The BSI hospitalization rate declined nonsignificantly over time (3.13 in 2009 to 2.98 in 2016, P = .08). Among pathogens, Escherichia coli (0.80 to 1.26), methicillin-sensitive Staphylococcus aureus (0.83 to 1.98), and group A Streptococcus (0.16 to 0.37) significantly increased for nonneonates, while Streptococcus pneumoniae (1.07 to 0.26) and Enterococcus spp. (0.60 to 0.17) declined. Regional differences were greatest for E. coli and highest in the New England and South Atlantic regions.

CONCLUSIONS

Trends in pediatric BSI hospitalization rates varied by pathogen and regionally. Overall the BSI hospitalization rate did not significantly decline, indicating a continued need to improve pediatric BSI assessment and prevention.

Effects of the proportion of high-risk patients and control strategies on the prevalence of methicillin-resistant Staphylococcus aureus in an intensive care unit

Background

The presence of nosocomial pathogens in many intensive care units poses a threat to patients and public health worldwide. Methicillin-resistant Staphylococcus aureus (MRSA) is an important pathogen endemic in many hospital settings. Patients who are colonized with MRSA may develop an infection that can complicate their prior illness.

Methods

A mathematical model to describe transmission dynamics of MRSA among high-risk and low-risk patients in an intensive care unit (ICU) via hands of health care workers is developed. We aim to explore the effects of the proportion of high-risk patients, the admission proportions of colonized and infected patients, the probability of developing an MRSA infection, and control strategies on MRSA prevalence among patients.

Results

The increasing proportion of colonized and infected patients at admission, along with the higher proportion of high-risk patients in an ICU, may significantly increase MRSA prevalence. In addition, the prevalence becomes higher if patients in the high-risk group are more likely to develop an MRSA infection. Our results also suggest that additional infection prevention and control measures targeting high-risk patients may considerably help reduce MRSA prevalence as compared to those targeting low-risk patients.

Conclusions

The proportion of high-risk patients and the proportion of colonized and infected patients in the high-risk group at admission may play an important role on MRSA prevalence. Control strategies targeting high-risk patients may help reduce MRSA prevalence.

Comparison of steam technology and a two-step cleaning (water/detergent) and disinfecting (1,000 resp. 5,000 ppm hypochlorite) method using microfiber cloth for environmental control of multidrug-resistant organisms in an intensive care unit

Aim: The aim of this prospective observational study was to evaluate the impact of two cleaning and disinfecting methods and the use of steam against methicillin-resistant Staphyl ococcus aureus, vancomycin-resistant Enterococcus faecalis, carbapenem-resistant Pseudomonas aeruginosa and multidrug-resistant (MDR) Acinetobacter baumannii in a tertiary referral hospital. Methods: McFarland 0.5 suspensions (content 1.5 x 10⁸ cfu/ml) of four challenge bacterial species were prepared and used to inoculate different sites in three ICU rooms. One of the following methods was used in each room: steam technology (Tecnovap Evo 304) resp. cleaning with microfiber cloths, soaked with detergent and water, thereafter disinfection with 1,000 ppm hypochlorite or the same procedure with 5,000 ppm hypochlorite. Qualitative microbiology and ATP bioluminescence were performed before and after cleaning with each method. The Wilcoxon test was used for paired samples to check for ordinal variables. The cost of each cleaning method was analyzed. Results: Environmental cleaning with steam technology was found to be as effective against MDR microorganisms as a two-step cleaning process (water/detergent and disinfecting with 1,000 resp. 5,000 ppm hypochlorite) in ICUs. No bacterial growth was detected after any of the three cleaning methods. Steam technology was 76% and 91% cheaper than using 5,000 ppm and 1,000 ppm hypochlorite, respectively. Conclusions: When compared to, steam technology was found to have an advantage over the 2-step procedure with cleaning and disinfection, because it avoids the use of chemicals, reduces water consumption, labor time and costs for cleaning.

Extracorporeal membrane oxygenation in patients with heart transplantation : A clinical prognosis analysis

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) is indicated for bridging to heart transplantation, graft failure, and right heart failure after heart transplantation. This study explored risk factors affecting the clinical prognosis of cardiac transplantation patients treated with ECMO during the perioperative period.

METHODS

Data on 28 heart transplantation patients with ECMO obtained from January 2012 to January 2018 in the People's Hospital of Zhongshan City were retrospectively analyzed.

RESULTS

A total of 25 patients (20 male and 5 female) were finally included. Heart transplantation was performed mainly due to cardiomyopathy (77.8%). Of the treated patients, 18 (72%) survived and were discharged, 4 were treated with cardiopulmonary resuscitation (CPR) before ECMO, and 3 died in hospital. There were no differences between the surviving and death group donors (N-terminal pro b‑type natriuretic peptide [NT-proBNP], creatine kinase-muscle/brain [CK-MB], warm ischemia time of donated heart, cold ischemia time of donated heart, total ischemia time of donated heart, and donor type). In univariate analysis, body mass index (BMI), length of stay in the intensive care unit (ICU), and CPR were relevant prognostic factors for heart transplantation patients with ECMO. Multi-factor logistic regression showed that CPR before ECMO (odds ratio, OR, 49.45; 95% confidence interval, CI, [1.37, 1781.6]; P = 0.033) is an independent risk factor influencing prognosis.

CONCLUSION

ECMO is an important life support method for patients before and after heart transplantation surgery. Obesity, poor preoperative cardiac function, and considerable intraoperative red blood cell transfusion may influence prognosis. Extracardiac compression before ECMO is an independent risk factor for prognosis.

Methicillin-resistant Staphylococcus aureus (MRSA): antibiotic-resistance and the biofilm phenotype

Staphylococcus aureus (S. aureus) is an asymptomatic colonizer of 30% of all human beings. While generally benign, antibiotic resistance contributes to the success of S. aureus as a human pathogen. Resistance is rapidly evolved through a wide portfolio of mechanisms including horizontal gene transfer and chromosomal mutation. In addition to traditional resistance mechanisms, a special feature of S. aureus pathogenesis is its ability to survive on both biotic and abiotic surfaces in the biofilm state. Due to this characteristic, S. aureus is a leading cause of human infection. Methicillin-resistant S. aureus (MRSA) in particular has emerged as a widespread cause of both community- and hospital-acquired infections. Currently, MRSA is responsible for 10-fold more infections than all multi-drug resistant (MDR) Gram-negative pathogens combined. Recently, MRSA was classified by the World Health Organization (WHO) as one of twelve priority pathogens that threaten human health. In this targeted mini-review, we discuss MRSA biofilm production, the relationship of biofilm production to antibiotic resistance, and front-line techniques to defeat the biofilm-resistance system.

A 2-Year Single-Centre Audit on Antibiotic Resistance of Pseudomonas aeruginosa, Acinetobacter baumannii and Klebsiella pneumoniae Strains from an Intensive Care Unit and Other Wards in a General Public Hospital in Greece

Hospital-acquired infections, particularly in the critical care setting, are becoming increasingly common during the last decade, with Gram-negative bacterial infections presenting the highest incidence among them. Multi-drug-resistant (MDR) Gram-negative infections are associated with high morbidity and mortality, with significant direct and indirect costs resulting from long hospitalization due to antibiotic failure. As treatment options become limited, antimicrobial stewardship programs aim to optimize the appropriate use of currently available antimicrobial agents and decrease hospital costs. Pseudomonas aeruginosa, Acinetobacter baumannii and Klebsiella pneumoniae are the most common resistant bacteria encountered in intensive care units (ICUs) and other wards. To establish preventive measures, it is important to know the prevalence of Gram-negative isolated bacteria and antibiotic resistance profiles in each ward separately, compared with ICUs. In our single centre study, we compared the resistance levels per antibiotic of P. aeruginosa, A. baumannii and K.pneumoniae clinical strains between the ICU and other facilities during a 2-year period in one of the largest public tertiary hospitals in Greece. The analysis revealed a statistically significant higher antibiotic resistance of the three bacteria in the ICU isolates compared with those from other wards. ICU strains of P. aeruginosa presented the highest resistance rates to gentamycin (57.97%) and cefepime (56.67%), followed by fluoroquinolones (55.11%) and carbapenems (55.02%), while a sensitivity rate of 97.41% was reported to colistin. A high resistance rate of over 80% of A. baumannii isolates to most classes of antibiotics was identified in both the ICU environment and regular wards, with the lowest resistance rates reported to colistin (53.37% in ICU versus an average value of 31.40% in the wards). Statistically significant higher levels of resistance to most antibiotics were noted in ICU isolates of K. pneumoniae compared with non-ICU isolates, with the highest difference—up to 48.86%—reported to carbapenems. The maximum overall antibiotic resistance in our ICU was reported for Acinetobacter spp. (93.00%), followed by Klebsiella spp. (72.30%) and Pseudomonas spp. (49.03%).

Methicillin-Resistant Staphylococcus aureus: Molecular Characterization, Evolution, and Epidemiology

Staphylococcus aureus, a major human pathogen, has a collection of virulence factors and the ability to acquire resistance to most antibiotics. This ability is further augmented by constant emergence of new clones, making S. aureus a "superbug." Clinical use of methicillin has led to the appearance of methicillin-resistant S. aureus (MRSA). The past few decades have witnessed the existence of new MRSA clones. Unlike traditional MRSA residing in hospitals, the new clones can invade community settings and infect people without predisposing risk factors. This evolution continues with the buildup of the MRSA reservoir in companion and food animals. This review focuses on imparting a better understanding of MRSA evolution and its molecular characterization and epidemiology. We first describe the origin of MRSA, with emphasis on the diverse nature of staphylococcal cassette chromosome mec (SCCmec). mecA and its new homologues (mecB, mecC, and mecD), SCCmec types (13 SCCmec types have been discovered to date), and their classification criteria are discussed. The review then describes various typing methods applied to study the molecular epidemiology and evolutionary nature of MRSA. Starting with the historical methods and continuing to the advanced whole-genome approaches, typing of collections of MRSA has shed light on the origin, spread, and evolutionary pathways of MRSA clones.

Hospital-associated methicillin-resistant Staphylococcus aureus: A cross-sectional analysis of risk factors in South African tertiary public hospitals

Introduction

Hospital-associated methicillin-resistant S. aureus (HA-MRSA) remains a significant cause of morbidity and mortality worldwide. We conducted a study to determine risk factors for HA-MRSA in order to inform control strategies in South Africa.

Methods

We used surveillance data collected from five tertiary hospitals in Gauteng and Western Cape provinces during 2014 for analysis. A case of HA-MRSA was defined as isolation of MRSA from a blood culture 48 hours after admission and/or if the patient was hospitalised in the six months prior to the current culture. Multivariable logistic regression modelling was used to determine risk factors for HA-MRSA.

Results

Of the 9971 patients with positive blood cultures, 7.7% (772) had S. aureus bacteraemia (SAB). The overall prevalence of MRSA among those with SAB was 30.9% (231/747; 95% confidence interval [CI] 27.6%– 34.3%). HA-MRSA infections accounted for 28.3% of patients with SAB (207/731; 95% CI 25.1%– 31.7%). Burns (adjusted odds ratio [aOR] 12.7; 95% CI 4.7–34.4), age ≤1 month (aOR 8.7; 95% CI 3.0–24.6), residency at a long-term care facility (aOR 5.2; 95% CI, 1.5–17.4), antibiotic use within two months of the current SAB episode (aOR 5.1; 95% CI 2.8–9.1), hospital stay of 13 days or more (aOR 2.8; 95% CI 1.3–5.6) and mechanical ventilation (aOR 2.2; 95% CI 1.07–4.6), were independent risk factors for HA-MRSA infection.

Conclusion

The prevalence of MRSA remains high in South African tertiary public hospitals. Several identified risk factors of HA-MRSA infections should be considered when instituting infection and prevention strategies in public-sector hospitals, including intensifying the implementation of antimicrobial stewardship programmes. There is an urgent need to strengthen infection prevention and control in burn wards, neonatal wards, and intensive care units which house mechanically ventilated patients.

Modeling risk for developing drug resistant bacterial infections in an MDR-naive critically ill population

PURPOSE

To create a model predictive of an individual's risk of developing a de novo multidrug-resistant (MDR) infection while in the intensive care unit (ICU).

METHODS

This is a case-control study in which 189 ICU patients diagnosed with their first infection with an MDR organism were compared on the basis of demographic, past medical and clinical variables to randomly selected ICU patients without such an infection, era-matched in a 2:1 ratio. A prediction tool was derived using multivariate logistic regression.

RESULTS

Five features remained predictive of developing an infection with a drug-resistant pathogen: hospitalization within a year [adjusted odds ratio (OR) 2.14], chronic hemodialysis (3.86), underlying oxygen-dependent pulmonary disease (1.86), endotracheal intubation within 24 h (2.46) and reason for ICU admission (respiratory failure 2.89, non-respiratory failure, non-shock presentation 1.85). Using a scoring system (0-7 points) based on the adjusted OR, risk categories were derived (low: 0-2 points, intermediate: 3-4 points and high risk: 5-7 points). The negative predictive value at a score cutoff of 2 is excellent (88.9%).

CONCLUSIONS

A clinical prediction rule comprised of five easily measured ICU variables reasonably discriminates between patients who will develop their first MDR infection versus those who will not.

Transmission of Staphylococcus aureus between health-care workers, the environment, and patients in an intensive care unit: a longitudinal cohort study based on whole-genome sequencing

Background

Health-care workers have been implicated in nosocomial outbreaks of Staphylococcus aureus, but the dearth of evidence from non-outbreak situations means that routine health-care worker screening and S aureus eradication are controversial. We aimed to determine how often S aureus is transmitted from health-care workers or the environment to patients in an intensive care unit (ICU) and a high-dependency unit (HDU) where standard infection control measures were in place.

Methods

In this longitudinal cohort study, we systematically sampled health-care workers, the environment, and patients over 14 months at the ICU and HDU of the Royal Sussex County Hospital, Brighton, England. Nasal swabs were taken from health-care workers every 4 weeks, bed spaces were sampled monthly, and screening swabs were obtained from patients at admission to the ICU or HDU, weekly thereafter, and at discharge. Isolates were cultured and their whole genome sequenced, and we used the threshold of 40 single-nucleotide variants (SNVs) or fewer to define subtypes and infer recent transmission.

Findings

Between Oct 31, 2011, and Dec 23, 2012, we sampled 198 health-care workers, 40 environmental locations, and 1854 patients; 1819 isolates were sequenced. Median nasal carriage rate of S aureus in health-care workers at 4-weekly timepoints was 36·9% (IQR 35·7–37·3), and 115 (58%) health-care workers had S aureus detected at least once during the study. S aureus was identified in 8–50% of environmental samples. 605 genetically distinct subtypes were identified (median SNV difference 273, IQR 162–399) at a rate of 38 (IQR 34–42) per 4-weekly cycle. Only 25 instances of transmission to patients (seven from health-care workers, two from the environment, and 16 from other patients) were detected.

Interpretation

In the presence of standard infection control measures, health-care workers were infrequently sources of transmission to patients. S aureus epidemiology in the ICU and HDU is characterised by continuous ingress of distinct subtypes rather than transmission of genetically related strains.

Funding

UK Medical Research Council, Wellcome Trust, Biotechnology and Biological Sciences Research Council, UK National Institute for Health Research, and Public Health England.

Antimicrobial Resistance in the Intensive Care Unit

Bacterial infections are a frequent cause of hospitalization, and nosocomial infections are an increasingly common condition, particularly within the acute/critical care setting. Infection control practices and new antimicrobial development have primarily focused on gram-positive bacteria; however, in recent years, the incidence of infections caused by gram-negative bacteria has risen considerably in intensive care units. Infections caused by multidrug-resistant (MDR) gram-negative organisms are associated with high morbidity and mortality, with significant direct and indirect costs resulting from prolonged hospitalizations due to antibiotic treatment failures. Of particular concern is the increasing prevalence of antimicrobial resistance to β-lactam antibiotics (including carbapenems) among Pseudomonas aeruginosa and Acinetobacter baumannii and, recently, among pathogens of the Enterobacteriaceae family. Treatment options for infections caused by these pathogens are limited. Antimicrobial stewardship programs focus on optimizing the appropriate use of currently available antimicrobial agents with the goals of improving outcomes for patients with infections caused by MDR gram-negative organisms, slowing the progression of antimicrobial resistance, and reducing hospital costs. Newly approved treatment options are available, such as β-lactam/β-lactamase inhibitor combinations, which significantly extend the armamentarium against MDR gram-negative bacteria.

Meticillin-resistant Staphylococcus aureus in the intensive care unit: its effect on outcome and risk factors for acquisition

BACKGROUND

Meticillin-resistant Staphylococcus aureus (MRSA) is a common cause of nosocomial infection in the intensive care unit (ICU). A perception exists that ICU-acquired MRSA is associated with poor outcomes, although there are few data to support this.

AIM

To determine the effect of acquiring MRSA in the ICU on 180-day mortality, and to identify risk factors associated with acquisition.

METHODS

Data were collected prospectively from 2007 to 2013. Patients who remained MRSA negative throughout their ICU admission were matched with patients who acquired MRSA in terms of age, Acute Physiology and Chronic Health Evaluation II score, length of ICU stay and surgical/non-surgical status.

FINDINGS

In total, 2405 patients were included in the analysis. Patients who acquired MRSA in the ICU had significantly longer ICU stays than patients who were admitted with MRSA and patients who remained MRSA negative throughout their ICU stay (P < 0.001 for both). There were no significant differences in 180-day mortality between the groups (P = 0.238). A confirmed non-MRSA infection within 48 h of ICU admission was associated with increased risk of MRSA acquisition (adjusted odds ratio 2.57, P = 0.005), and receipt of antimicrobial therapy within 48 h of ICU admission was associated with reduced risk of MRSA acquisition (adjusted odds ratio 0.38, P = 0.014).

CONCLUSION

MRSA acquisition does not contribute towards mortality in critically ill patients. This raises questions regarding the cost-effectiveness of focusing infection prevention measures on the control of MRSA in ICUs. The low acquisition rate and lack of risk factors identified for MRSA in the study cohort indicate that efforts should be directed towards continual improvement of standard infection control procedures for all patients.

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.

Ecology of blood stream infection and antibiotic resistance in intensive care unit at a tertiary care hospital in North India

Objective

To analyse the prevalent microorganisms and their antimicrobial resistance among intensive care unit patients in a tertiary care centre in New Delhi.

Methods

A retrospective study of all consecutive blood cultures from various intensive care unit patients in the hospital during four years (January 2008 to December 2011). Antibiotic consumption data in the intensive care units were also analysed during the same period.

Results

Out of the total 22,491 blood cultures processed, 2846 samples were positive and 3771 microorganisms were isolated. The blood culture positivity was estimated as 12.7% of which 67.5% were monomicrobial and 32.5% polymicrobial infections. Gram negative bacilli, Gram positive cocci, and fungi were isolated in 49%, 33%, and 18% cases, respectively. Coagulase negative staphylococcus was the commonest single isolate followed by Candida spp. A drastic shift in the distribution of Candida spp. towards nonalbicans along with high resistance to azole group of antifungals suggest echinocandins for the empiric therapy of candidemia. High penicillin resistance in Gram positive isolates suggest vancomycin, linezolid and tigecycline as the options for empiric therapy, whereas tigecycline and colistin are the only options remaining for highly resistant Gram negative isolates. Aminoglycosides were observed to have better sensitivity and reduced usage when compared with cephalosporins and β-lactam + β-lactam inhibitor combinations.

Conclusions

High frequencies of multidrug resistant organisms were observed in intensive care units which is a warning as to use the only few effective antimicrobials wisely to reduce selective pressure on sensitive strains.

Staphylococcal enterotoxin P predicts bacteremia in hospitalized patients colonized with methicillin-resistant Staphylococcus aureus

BACKGROUND

Methicillin-resistant Staphylococcus aureus (MRSA) colonization predicts later infection, with both host and pathogen determinants of invasive disease.

METHODS

This nested case-control study evaluates predictors of MRSA bacteremia in an 8-intensive care unit (ICU) prospective adult cohort from 1 September 2003 through 30 April 2005 with active MRSA surveillance and collection of ICU, post-ICU, and readmission MRSA isolates. We selected MRSA carriers who did (cases) and those who did not (controls) develop MRSA bacteremia. Generating assembled genome sequences, we evaluated 30 MRSA genes potentially associated with virulence and invasion. Using multivariable Cox proportional hazards regression, we assessed the association of these genes with MRSA bacteremia, controlling for host risk factors.

RESULTS

We collected 1578 MRSA isolates from 520 patients. We analyzed host and pathogen factors for 33 cases and 121 controls. Predictors of MRSA bacteremia included a diagnosis of cancer, presence of a central venous catheter, hyperglycemia (glucose level, >200 mg/dL), and infection with a MRSA strain carrying the gene for staphylococcal enterotoxin P (sep). Receipt of an anti-MRSA medication had a significant protective effect.

CONCLUSIONS

In an analysis controlling for host factors, colonization with MRSA carrying sep increased the risk of MRSA bacteremia. Identification of risk-adjusted genetic determinants of virulence may help to improve prediction of invasive disease and suggest new targets for therapeutic intervention.

Molecular epidemiological analysis of methicillin-resistant Staphylococcus aureus isolates from a medical intensive care unit: a comparison of nasal and clinical isolates

BACKGROUND

The control of nosocomial transmission of methicillin-resistant Staphylococcus aureus (MRSA) represents a significant challenge to infection control professionals. Nasal carriage colonization by MRSA plays a crucial role in the epidemiology and pathogenesis of this infection.

METHODS

Patients in the medical intensive care unit (ICU) between November 2010 and March 2011 were swabbed when hospitalized, reswabbed 1 week later and for a third time, when they were discharged from the ICU. All swabs were examined within 2 hours of collection using ChromID MRSA-Select agar plates to detect MRSA. Positive specimens were determined to have the mecA and femB gene through amplification with duplex polymerase chain reaction. Repetitive element sequence-based polymerase chain reaction was used to investigate the epidemiological types of MRSA isolates in the third screening and clinical isolates obtained from 2007 to 2010 in West China Hospital. A comparison of molecular types was performed to investigate the genetic relationship between nasal and clinical isolates.

RESULTS

After the third screening, 16 nasal MRSA isolates were identified. Epidemiological analysis revealed that 16 nasal MRSA isolates and 37 clinical MRSA isolates differentiated into 2 clusters, comprising 9 subclusters. Of the 16 nasal strains, 11 (68.8%) belonged to subcluster I of cluster I; 3 of 9 subclusters consisted of both nasal and clinical isolates, while 4 of 9 subclusters consisted of clinical isolates and only 2 of 9 consisted of nasal isolates.

CONCLUSIONS

Our study indicated a high degree of genetic relatedness between nasal and clinical MRSA isolates. The molecular typing of MRSA is critical for controlling the nosocomial transmission of this pathogen in ICU setting and defining a nosocomial infection control policy.

The implications of the presence of osteomyelitis on outcomes of infected diabetic foot wounds

AIM

To assess the effect of the presence of osteomyelitis in patients with a diabetic foot infection.

METHODS

We reviewed the records of diabetic patients hospitalized at our medical center for a foot infection over a 2-y period. Using clinical, imaging, and microbiology results, we classified each patient as having diabetic foot osteomyelitis (DFO) or not. We then compared several outcome criteria of interest between the 2 groups.

RESULTS

Among 73 eligible patients, 37 were in the DFO group (DFO group), while the other 36 were in the soft tissue infection group (STI group). In comparison to the STI group, the DFO group had a significantly longer length of stay (LOS) in the hospital (42 (28.5-51) days vs 19.5 (13.2-29.5) days, p < 0.001), longer duration of antibiotic therapy (46.6 ± 19.9 days vs 22.0 ± 14.6 days, p < 0.001), longer duration of intravenous antibiotic therapy (32.3 ± 16.3 days vs 13.6 ± 14.3 days, p < 0.001), longer duration of wound before admission (44 (31-64.5) days vs 33 (23-45.5) days, p = 0.034), and longer time to wound healing (239.8 ± 108.2 days vs 183.1 ± 73 days, p = 0.011). There were more surgical procedures in the DFO group than in the STI group (24/37 (64.8%) vs 11/36 (30.5%), p = 0.003), and during hospitalization, 22 patients in the DFO group and 5 patients in STI group underwent minor amputation (59.4% vs 13.8%, p < 0.001).

CONCLUSION

The presence of osteomyelitis negatively affects both the treatment and outcome of diabetic foot infections.

Outcomes of health care-associated pneumonia empirically treated with guideline-concordant regimens versus community-acquired pneumonia guideline-concordant regimens for patients admitted to acute care wards from home

BACKGROUND

The introduction of the health care-associated pneumonia (HCAP) categorization expanded recommendations for broad-spectrum empiric antibiotics to pneumonia patients presenting from the community with recent health care-system exposure. However, the efficacy of such regimens in improving clinical outcomes in these patients has not been well established.

OBJECTIVE

To compare the clinical outcomes of HCAP patients treated initially with HCAP guideline-concordant antibiotic regimens to those treated initially with community-acquired pneumonia (CAP) guideline-concordant antibiotic regimens.

METHODS

This retrospective study included HCAP patients presenting from home and admitted to general medical wards. HCAP regimen patients were treated empirically with at least 1 antipseudomonal agent. All other patients were assigned to the CAP regimen group. The primary end point was clinical cure at 30 days postdischarge. Subgroup analysis was performed in patients hospitalized 1-30 days and 31-90 days before the HCAP admission.

RESULTS

Of 228 HCAP admissions, 122 patients received CAP regimens and 106 received HCAP regimens. The 2 groups were similar at baseline, including Pneumonia Severity Index scores. Attributable clinical cure occurred in 75.4% of CAP regimen patients and 69.8% of HCAP regimen patients (p = 0.34). Overall clinical cure occurred in 59.8% of CAP regimen patients and 54.7% of HCAP regimen patients (p = 0.44). The CAP regimen group used fewer days of intravenous antibiotics (4.39 vs 7.75, p < 0.0001) and had shorter lengths of stay (6.36 vs 8.58 days, p < 0.0001). For patients hospitalized 31-90 days earlier, clinical cure was higher in the CAP regimen group (attributable, 82.9% vs 60.0%, p = 0.0090; overall, 67.1% vs 47.5%, p = 0.044).

CONCLUSIONS

Compared to CAP guideline-concordant regimens, treatment of HCAP with HCAP guideline-concordant regimens did not increase clinical cure rates and was associated with lower clinical cure rates in patients hospitalized 31-90 days prior to the HCAP admission. This study suggests that broad-spectrum empiric antibiotics may not be necessary in all HCAP patient groups.

Increased prevalence of methicillin-resistant Staphylococcus aureus nasal colonization in household contacts of children with community acquired disease

Background

To measure Methicillin-resistant Staphylococcus aureus (MRSA) nasal colonization prevalence in household contacts of children with current community associated (CA)-MRSA infections (study group) in comparison with a group of household contacts of children without suspected Staphylococcus aureus infection (a control group).

Methods

This is a cross sectional study. Cultures of the anterior nares were taken. Relatedness of isolated strains was tested using pulse field gel electrophoresis (PFGE).

Results

The prevalence of MRSA colonization in the study group was significantly higher than in the control group (18/77 (23%) vs 3/77 (3.9%); p ≤ 0.001). The prevalence of SA colonization was 28/77 (36%) in the study group and 16/77 (21%) in the control group (p = 0.032). The prevalence of SA nasal colonization among patients was 6/24 (25%); one with methicillin-susceptible S. aureus (MSSA) and 5 with MRSA. In the study (patient) group, 14/24 (58%) families had at least one household member who was colonized with MRSA compared to 2/29 (6.9%) in the control group (p = 0.001). Of 69 total isolates tested by PFGE, 40 (58%) were related to USA300. Panton-Valetine leukocidin (PVL) genes were detected in 30/52 (58%) tested isolates. Among the families with ≥1 contact colonized with MRSA, similar PFGE profiles were found between the index patient and a contact in 10/14 families.

Conclusions

Prevalence of asymptomatic nasal carriage of MRSA is higher among household contacts of patients with CA-MRSA disease than control group. Decolonizing such carriers may help prevent recurrent CA-MRSA infections.

Early ICU energy deficit is a risk factor for Staphylococcus aureus ventilator-associated pneumonia

BACKGROUND

Caloric insufficiency during the first week of ICU stay has been associated with increased infection rates. The connection between specific pathogens and host nutritional status in the ICU is not well known. This study was undertaken to determine the impact of patients' early in-ICU energy balance on the pathogens responsible for ventilator-associated pneumonia (VAP).

METHODS

In this prospective, observational, cohort study conducted in a teaching hospital ICU, energy balance (energy delivered - calculated resting energy expenditure) was compared according to the microbiologic results of the fiber-optic BAL cultures of 76 consecutive patients receiving acute prolonged (≥ 96 h) mechanical ventilation who developed VAP during their ICU stay.

RESULTS

Among the 76 BAL cultures, 22 contained significant Staphylococcus aureus concentrations. The cumulated energy deficit of patients with S aureus VAP was greater than those with VAP caused by other pathogens (-10,275 ± 4,211 kcal vs -7,376 ± 4,013 kcal from ICU admission to day of BAL, P < .01). ICU admission, nutritional status, and conditions potentially limiting feeding did not differ significantly between the two groups. Patients with S aureus VAP had lower prescribed and delivered energy, causing higher energy deficits. Multivariate analysis identified energy deficit as being independently associated with S aureus VAP. More-severe energy deficit and higher rate of S aureus-positive BAL cultures (P = .01 comparing quartiles) were observed.

CONCLUSIONS

Early ICU energy deficit is an independent determinant for acquiring S aureus VAP in patients on acute prolonged mechanical ventilation.

Estimating the impact of healthcare-associated infections on length of stay and costs

Healthcare-associated infections (HAIs) unquestionably have substantial effects on morbidity and mortality. However, quantifying the exact economic burden attributable to HAIs still remains a challenging issue. Inaccurate estimations may arise from two major sources of bias. First, factors other than infection may affect patients' length of stay (LOS) and healthcare utilization. Second, HAI is a time-varying exposure, as the infection can impact on LOS and costs only after the infection has started. The most frequent mistake in previously published evidence is the introduction of time-dependent information as time-fixed, on the assumption that the impact of such exposure on the outcome was already present on admission. Longitudinal and multistate models avoid time-dependent bias and address the time-dependent complexity of the data. Appropriate statistical methods are important in analysis of excess costs and LOS associated with HAI, because informed decisions and policy developments may depend on them.

Evaluation of surface contamination with staphylococci in a veterinary hospital using a quantitative microbiological method

OBJECTIVES

To evaluate microbial contamination of the environment in a veterinary hospital using standards recommended for human hospitals and to provide a baseline against which further investigations can be compared.

METHODS

Surfaces were sampled twice daily for five consecutive days using a contact-based counting method to measure the levels of staphylococci in colony forming units (cfu) per cm².

RESULTS

Current recommendations for human hospitals were applied in this study; all samples with <2.5 cfu/cm² staphylococci were considered to have passed and those with ≥2.5 cfu/cm² to have failed. Of all the samples, 55.9% failed. The ICU did not have significantly higher failure rates than other areas of the hospital. The floor as a surface was associated with greater than a threefold increase in odds of elevated cfu concentrations relative to the door handle.

CLINICAL SIGNIFICANCE

This study provides information on the microbiological cleanliness of a veterinary teaching hospital using techniques and standards adopted by the food industry and recommended for human hospitals. This data can be used as a baseline for other hospitals, to evaluate the effectiveness in improvements in hygiene and cleaning measures and to design effective hospital cleaning protocols and assess ongoing hygiene standards.

Methicillin-resistant Staphylococcus aureus nosocomial infection trends in Hospital Universiti Sains Malaysia during 2002-2007

BACKGROUND AND OBJECTIVES

Methicillin-resistant Staphylococcus aureus (MRSA) is a major nosocomial pathogen that causes severe morbidity and mortality in many hospitals worldwide. The aim of the present study was to assess the burden of MRSA nosocomial infection, its association with factors of interest, and its antimicrobial susceptibility.

METHODS

This was a retrospective analysis of a database of all S aureus that were cultured from patients admitted to the different wards of Hospital Universiti Sains Malaysia (HUSM) over a period of 6 years.

RESULTS

The MRSA infections rate was 10.0 per 1000 hospital admissions. The incidence density rate of MRSA infections during the study period was 1.8 per 1000 patient-days, with annual rates ranging from 0.95 to 3.47 per 1000 patient-days. Duration of hospitalization, previous antibiotic use, and bedside invasive procedures were significantly higher among MRSA than methicillin-sensitive S aureus patients (P>.05). The highest number of MRSA infections were found in orthopedic wards (25.3%), followed by surgical wards (18.2%) and intensive care units (ICUs) (16.4%). All MRSA isolates were resistant to erythromycin (98.0%), co-trimoxazole (94.0%) and gentamicin (92.0%). Clindamycin was the best antibiotic with only 6% resistance. All MRSA isolates were sensitive to vancomycin.

CONCLUSION

The rate of nosocomial MRSA infection per 1000 admissions was higher than that in other studies. The three factors associated most significantly with acquired MRSA infections included duration of hospitalization, antibiotic use, and bedside invasive procedures. This study confirmed that vancomycin-resistant S aureus has not yet been established in HUSM.

Staphylococcus aureus nasal colonization and subsequent infection in intensive care unit patients: does methicillin resistance matter?

BACKGROUND

Staphylococcus aureus is an important cause of infection in intensive care unit (ICU) patients. Colonization with methicillin-resistant S. aureus (MRSA) is a risk factor for subsequent S. aureus infection. However, MRSA-colonized patients may have more comorbidities than methicillin-susceptible S. aureus (MSSA)-colonized or noncolonized patients and therefore may be more susceptible to infection on that basis.

OBJECTIVE

To determine whether MRSA-colonized patients who are admitted to medical and surgical ICUs are more likely to develop any S. aureus infection in the ICU, compared with patients colonized with MSSA or not colonized with S. aureus, independent of predisposing patient risk factors.

DESIGN

Prospective cohort study.

SETTING

A 24-bed surgical ICU and a 19-bed medical ICU of a 1,252-bed, academic hospital.

PATIENTS

A total of 9,523 patients for whom nasal swab samples were cultured for S. aureus at ICU admission during the period from December 2002 through August 2007.

METHODS

Patients in the ICU for more than 48 hours were examined for an ICU-acquired S. aureus infection, defined as development of S. aureus infection more than 48 hours after ICU admission.

RESULTS

S. aureus colonization was present at admission for 1,433 (27.8%) of 5,161 patients (674 [47.0%] with MRSA and 759 [53.0%] with MSSA). An ICU-acquired S. aureus infection developed in 113 (2.19%) patients, of whom 75 (66.4%) had an infection due to MRSA. Risk factors associated with an ICU-acquired S. aureus infection included MRSA colonization at admission (adjusted hazard ratio, 4.70 [95% confidence interval, 3.07-7.21]) and MSSA colonization at admission (adjusted hazard ratio, 2.47 [95% confidence interval, 1.52-4.01]).

CONCLUSION

ICU patients colonized with S. aureus were at greater risk of developing a S. aureus infection in the ICU. Even after adjusting for patient-specific risk factors, MRSA-colonized patients were more likely to develop S. aureus infection, compared with MSSA-colonized or noncolonized patients.

Risk factors and mortality of nosocomial infections of methicillin-resistant Staphylococcus aureus in an intensive care unit

PURPOSE

Methicillin-resistant Staphylococcus aureus (MRSA) infections are an increasing worldwide problem. We determined risk factors and predictors of mortality of MRSA nosocomial infections (NIs).

MATERIALS AND METHODS

A prospective cohort study was performed in an adult mixed medical and surgical intensive care unit from 2003 to 2007. Stratified analyses and generalized linear modeling were used to assess risk factors and predictors of infection and mortality.

RESULTS

A total of 184 infections (3.6% of all infections) were due to S aureus, and 97.8% of these were methicillin resistant. The most common infection sites were respiratory tract (35.6%) and bloodstream (30.6%). Stratified analyses of length of stay (LOS) before onset of MRSA NI and death indicated that MRSA infection (odds ratio [OR], 38.49; 95% confidence interval [CI], 25.53-58.09) and mortality (OR, 4.72; 95% CI, 1.92-11.99) were more likely for LOS more than 15 days than for LOS less than 7 days. After controlling for potentially confounding factors by use of generalized linear modeling analysis, we identified the following as independent risk factors: LOS before onset of MRSA infection (OR, 1.03; 95% CI, 0.01-1.04), serum creatinine (OR, 5.87; 95% CI, 1.37-9.21) level, use of mechanical ventilator (OR, 6.71; 95% CI, 1.58-8.5), and central venous catheter (OR, 1.13; 95% CI, 1.05-1.31).

CONCLUSIONS

Methicillin resistance is very common with S aureus infection. In our intensive care unit, use of invasive devices/procedures and LOS were the most important risk factors for infection.

A European survey of antibiotic management of methicillin-resistant Staphylococcus aureus infection: current clinical opinion and practice

Although the epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) varies across Europe, healthcare-associated MRSA infections are common in many countries. Despite several national guidelines, the approach to treatment of MRSA infections varies across the continent, and there are multiple areas of management uncertainty for which there is little clinical evidence to guide practice. A faculty, convened to explore some of these areas, devised a survey that was used to compare the perspectives of infection specialists from across Europe on the management of MRSA infections with those of the faculty specialists. The survey instrument, a web-based questionnaire, was sent to 3840 registered delegates of the 19th European Congress of Clinical Microbiology and Infectious Diseases, held in April 2009. Of the 501 (13%) respondents to the survey, 84% were infection/microbiology specialists and 80% were from Europe. This article reports the survey results from European respondents, and shows a broad range of opinion and practice on a variety of issues pertaining to the management of minor and serious MRSA infections, such as pneumonia, bacteraemia, and skin and soft tissue infections. The issues include changing epidemiology, when and when not to treat, choice of treatment, and duration and route of treatment. The survey identified areas where practice can be improved and where further research is needed, and also identified areas of pan-European consensus of opinion that could be applied to European guidelines for the management of MRSA infection.

Characterization of the best anatomical sites in screening for methicillin-resistant Staphylococcus aureus colonization

The purpose of this study was to identify differences in the sensitivity of anatomical sites sampling for methicillin-resistant Staphylococcus aureus (MRSA) colonization related to age, gender, clinical situation, and acquisition source as a base for screening protocols. We used a database that included all MRSA-positive cultures (Carmel Medical Center, 2003-2006) taken from nares, throat, perineum, and infection sites. The study population of 597 patients was divided into: "screening sample" (SS), which were cases of routine screening, and "clinical diagnostic sample" (CDS), which were patients with concurrent MRSA infection. MRSA acquisition sources were classified as internal medicine, surgical, referral patients, or intensive care unit (ICU). CDS patients were older than SS patients (median age 78 vs. 74 years, p = 0.0002), more commonly throat colonized (47.5% vs. 31.8%, p = 0.0001), and colonized in more multiple sites (65.7% vs. 43.3% were colonized in three sites in the CDS and SS groups, respectively, p < 0.001) than SS patients. In the SS, group throat colonization was higher in internal medicine wards than in the ICU (odds ratio [OR] = 3.98, p < 0.0001). In the CDS group, perineal colonization was more common in referral patients than in the ICU (OR = 4.52, p < 0.05). Patient age was the most influential factor on nares and multiple sites colonization in the SS and CDS groups, respectively. Our data support multiple sites sampling. Throat cultures are crucial in MRSA-infected patients and internal medicine ward patients. Multiple body sites colonization is more likely in older or MRSA-infected patients, affecting decisions regarding eradication using topical antibiotics.

Airborne transmission of disease in hospitals

Hospital-acquired infection (HAI) is an important public health issue with unacceptable levels of morbidity and mortality, over the last 5 years. Disease can be transmitted by air (over large distances), by direct/indirect contact or a combination of both routes. While contact transmission of disease forms the majority of HAI cases, transmission through the air is harder to control, but one where the engineering sciences can play an important role in limiting the spread. This forms the focus of this themed volume. In this paper, we describe the current hospital environment and review the contributions from microbiologists, mechanical and civil engineers, and mathematicians to this themed volume on the airborne transmission of infection in hospitals. The review also points out some of the outstanding scientific questions and possible approaches to mitigating transmission.

[Bacterial infections in critically ill patients: review of studies published between 2006 and 2008]

A systematic revision of medical publications between 2006 and 2008 regarding bacterial infections that affect the critical patients was performed. Four subjects were selected: Community-acquired pneumonia, ventilator-associated pneumonia, catheter-related bloodstream infection and new antimicrobial treatments. When dealing with community-acquired pneumonia and due to the absence of completely reliable standards, it is necessary to follow the locally adapted guidelines of clinical practice, to identify patients related to the health-care system and admit patients to the ICU in accordance with the criteria. Regarding the etiological diagnosis of ventilator-associated pneumonia, any microbiological information available must be used. Due to the risk of multidrug bacteria, combined empiric therapy should be initiated immediately and then mono-therapy adjusted to the antibiogram should be established. Already established measures for mechanical ventilation associated pneumonia and catheter-related bacteriemias, which have been effective, should be implemented. The empirical treatment of catheter-related bacteremia must be directed towards the most probable pathogens according to the puncture site. The most recently sold antibiotics are basically directed towards multidrug gram positive resistant bacteria. However, for the treatment of gram negative resistant bacilli, the use of the new antimicrobials must be combined with a new evaluation of the antibiotics that have been used for years and the possibility of choosing different administration forms.

Healthcare-associated Infections: epidemiology, prevention, and therapy

Reducing nosocomial infection rates is a major component of healthcare improvement. This article reviews the epidemiology, prevention, and therapy for some of the most common healthcare-associated infections, including central line-associated bloodstream infections and catheter-associated urinary tract infections, and 3 common organisms: methicillin-resistant Staphylococcus aureus, multidrug- resistant gram-negative bacteria, and Clostridium difficile.

Acquisition and cross-transmission of Staphylococcus aureus in European intensive care units

OBJECTIVE

To study the acquisition and cross-transmission of Staphylococcus aureus in different intensive care units (ICUs).

METHODS

We performed a multicenter cohort study. Six ICUs in 6 countries participated. During a 3-month period at each ICU, all patients had nasal and perineal swab specimens obtained at ICU admission and during their stay. All S. aureus isolates that were collected were genotyped by spa typing and multilocus variable-number tandem-repeat analysis typing for cross-transmission analysis. A total of 629 patients were admitted to ICUs, and 224 of these patients were found to be colonized with S. aureus at least once during ICU stay (22% were found to be colonized with methicillin-resistant S. aureus [MRSA]). A total of 316 patients who had test results negative for S. aureus at ICU admission and had at least 1 follow-up swab sample obtained for culture were eligible for acquisition analysis.

RESULTS

A total of 45 patients acquired S. aureus during ICU stay (31 acquired methicillin-susceptible S. aureus [MSSA], and 14 acquired MRSA). Several factors that were believed to affect the rate of acquisition of S. aureus were analyzed in univariate and multivariate analyses, including the amount of hand disinfectant used, colonization pressure, number of beds per nurse, antibiotic use, length of stay, and ICU setting (private room versus open ICU treatment). Greater colonization pressure and a greater number of beds per nurse correlated with a higher rate of acquisition for both MSSA and MRSA. The type of ICU setting was related to MRSA acquisition only, and the amount of hand disinfectant used was related to MSSA acquisition only. In 18 (40%) of the cases of S. aureus acquisition, cross-transmission from another patient was possible.

CONCLUSIONS

Colonization pressure, the number of beds per nurse, and the treatment of all patients in private rooms correlated with the number of S. aureus acquisitions on an ICU. The amount of hand disinfectant used was correlated with the number of cases of MSSA acquisition but not with the number of cases of MRSA acquisition. The number of cases of patient-to-patient cross-transmission was comparable for MSSA and MRSA.

Outcomes of colonization with MRSA and VRE among liver transplant candidates and recipients

Methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococcus (VRE) infections cause significant morbidity and mortality among liver transplant candidates and recipients. To assess rates of MRSA and VRE colonization, we obtained active surveillance cultures from 706 liver transplant candidates and recipients within 24 h of admission to an 11-bed liver transplant ICU from October 2000 to December 2005. Patients were followed prospectively to determine the cumulative risk of MRSA or VRE infection or death by colonization status. Outcomes were assessed by Kaplan-Meier survival analysis and Cox regression and multivariate logistic regression adjusting for covariates. The prevalence of newly detected MRSA nasal and VRE rectal colonization was 6.7% and 14.6%, respectively. Liver transplant candidates and recipients with MRSA colonization had an increased risk of MRSA infection (adjusted OR = 15.64, 95% CI 6.63-36.89) but not of death (adjusted OR = 1.00, 95% CI 0.43-2.30), whereas those with VRE colonization had an increased risk both of VRE infection (adjusted OR = 3.61, 95% CI 2.01-6.47) and of death (adjusted OR = 2.12, 95% CI 1.27-3.54) compared with noncolonized patients. Prevention and control strategies, including use of active surveillance cultures, should be implemented to reduce the rates of both MRSA and VRE colonization in this high-risk patient population.

MRSA detection: comparison of two molecular methods (BD GeneOhm PCR assay and Easy-Plex) with two selective MRSA agars (MRSA-ID and Oxoid MRSA) for nasal swabs

Screening of patients is an important component for methicillin-resistant Staphylococcus aureus (MRSA) containment. The aim of this study was to determine the utility of molecular methods compared to selective agars for MRSA detection. Consecutive high risk patients (n = 200) were screened for nasal MRSA colonization using chromogenic selective agars (MRSA ID and CMRSA) as well as the BD GeneOhm MRSA (previously known as IDI-MRSA) and the Easy-Plex commercial real time PCR assays. The sensitivities of the molecular methods were similar to the BD GeneOhm MRSA (86%) and Easy-Plex (84%). The chromogenic agars, MRSA ID and CMRSA, showed sensitivities of 62% and 84%, respectively. Sensitivity was influenced by both the MRSA antibiograms and MRSA clonal type. The specificity was >98% in all methods except for the Easy-Plex assay (90%). Sensitivity of selective agars increased with 48 hours of incubation with a corresponding decrease in specificity. In conclusion, molecular detection methods for MRSA remain sensitive and rapid but are associated with greater expense.