Risk factors for the development of active methicillin-resistant Staphylococcus aureus (MRSA) infection in patients colonized with MRSA at hospital admission

Deep learning model for personalized prediction of positive MRSA culture using time-series electronic health records

Methicillin-resistant Staphylococcus aureus (MRSA) poses significant morbidity and mortality in hospitals. Rapid, accurate risk stratification of MRSA is crucial for optimizing antibiotic therapy. Our study introduced a deep learning model, PyTorch_EHR, which leverages electronic health record (EHR) time-series data, including wide-variety patient specific data, to predict MRSA culture positivity within two weeks. 8,164 MRSA and 22,393 non-MRSA patient events from Memorial Hermann Hospital System, Houston, Texas are used for model development. PyTorch_EHR outperforms logistic regression (LR) and light gradient boost machine (LGBM) models in accuracy (AUROCPyTorch_EHR = 0.911, AUROCLR = 0.857, AUROCLGBM = 0.892). External validation with 393,713 patient events from the Medical Information Mart for Intensive Care (MIMIC)-IV dataset in Boston confirms its superior accuracy (AUROCPyTorch_EHR = 0.859, AUROCLR = 0.816, AUROCLGBM = 0.838). Our model effectively stratifies patients into high-, medium-, and low-risk categories, potentially optimizing antimicrobial therapy and reducing unnecessary MRSA-specific antimicrobials. This highlights the advantage of deep learning models in predicting MRSA positive cultures, surpassing traditional machine learning models and supporting clinicians' judgments.

Natural products acting against S. aureus through membrane and cell wall disruption

Covering: 2015 to 2022Staphylococcus aureus (S. aureus) is responsible for several community and hospital-acquired infections with life-threatening complications such as bacteraemia, endocarditis, meningitis, liver abscess, and spinal cord epidural abscess. In recent decades, the abuse and misuse of antibiotics in humans, animals, plants, and fungi and the treatment of nonmicrobial diseases have led to the rapid emergence of multidrug-resistant pathogens. The bacterial wall is a complex structure consisting of the cell membrane, peptidoglycan cell wall, and various associated polymers. The enzymes involved in bacterial cell wall synthesis are established antibiotic targets and continue to be a central focus for antibiotic development. Natural products play a vital role in drug discovery and development. Importantly, natural products provide a starting point for active/lead compounds that sometimes need modification based on structural and biological properties to meet the drug criteria. Notably, microorganisms and plant metabolites have contributed as antibiotics for noninfectious diseases. In this study, we have summarized the recent advances in understanding the activity of the drugs or agents of natural origin that directly inhibit the bacterial membrane, membrane components, and membrane biosynthetic enzymes by targeting membrane-embedded proteins. We also discussed the unique aspects of the active mechanisms of established antibiotics or new agents.

Is nanomaterial- and vancomycin-loaded polymer coating effective at preventing methicillin-resistant Staphylococcus aureus growth on titanium disks? An in vitro study

PURPOSE

Periprosthetic joint infections induced by methicillin-resistant Staphylococcus aureus (MRSA) pose a major socioeconomic burden. Given the fact that MRSA carriers are at high risk for developing periprosthetic infections regardless of the administration of eradication treatment pre-operatively, the need for developing new prevention modalities is high.

METHODS

The antibacterial and antibiofilm properties of vancomycin, Al₂O₃ nanowires, and TiO₂ nanoparticles were evaluated in vitro using MIC and MBIC assays. MRSA biofilms were grown on titanium disks simulating orthopedic implants, and the infection prevention potential of vancomycin-, Al₂O₃ nanowire-, and TiO₂ nanoparticle-supplemented Resomer® coating was evaluated against biofilm controls using the XTT reduction proliferation assay.

RESULTS

Among the tested modalities, high- and low-dose vancomycin-loaded Resomer® coating yielded the most satisfactory metalwork protection against MRSA (median absorbance was 0.1705; [IQR = 0.1745] vs control absorbance 0.42 [IQR = 0.07]; p = 0.016; biofilm reduction was 100%; and 0.209 [IQR = 0.1295] vs control 0.42 [IQR = 0.07]; p < 0.001; biofilm reduction was 84%, respectively). On the other hand, polymer coating alone did not provide clinically meaningful biofilm growth prevention (median absorbance was 0.2585 [IQR = 0.1235] vs control 0.395 [IQR = 0.218]; p < 0.001; biofilm reduction was 62%).

CONCLUSIONS

We advocate that apart from the well-established preventative measures for MRSA carriers, loading implants with bioresorbable Resomer® vancomycin-supplemented coating may decrease the incidence of early post-op surgical site infections with titanium implants. Of note, the payoff between localized toxicity and antibiofilm efficacy should be considered when loading polymers with highly concentrated antimicrobial agents.

Tackling multidrug-resistant Staphylococcus aureus by natural products and their analogues acting as NorA efflux pump inhibitors

Staphylococcus aureus (S. aureus) is a pathogen responsible for various community and hospital-acquired infections with life-threatening complications like bacteraemia, endocarditis, meningitis, liver abscess, and spinal cord epidural abscess. Antibiotics have been used to treat microbial infections since the introduction of penicillin in 1940. In recent decades, the abuse and misuse of antibiotics in humans, animals, plants, and fungi, including the treatment of non-microbial diseases, have led to the rapid emergence of multidrug-resistant pathogens with increased virulence. Bacteria have developed several complementary mechanisms to avoid the effects of antibiotics. These mechanisms include chemical transformations and enzymatic inactivation of antibiotics, modification of antibiotics' target site, and reduction of intracellular antibiotics concentration by changes in membrane permeability or by the overexpression of efflux pumps (EPs). The strategy to check antibiotic resistance includes synthesis of the antibiotic analogues, or antibiotics are given in combination with the adjuvant. The inhibitors of multidrug EPs are considered promising alternative therapeutic options with the potential to revive the effects of antibiotics and reduce bacterial virulence. Natural products played a vital role in drug discovery and significantly contributed to the area of infectious diseases. Also, natural products provide lead compounds that sometimes need modification based on structural and biological properties to meet the drug criteria. This review discusses natural products and their derived compounds as NorA efflux pump inhibitors (EPIs).

Do patients need advice and information to prevent infections - results of a single centre structured survey

Background

Healthcare-associated infections are a major burden for hospitals, leading to morbidity and mortality and unnecessary medical costs. They can probably be reduced through what is known as patient empowerment. This study aims to address the question of whether patients are interested in receiving infection prevention and control information.

Methods

Patients were asked in structured interviews whether they would like more information on infection prevention and control. Inclusion criteria comprised 2 groups of patients. Group 1 were patients undergoing elective total endoprosthesis (TEP) and Group 2 were patients tested positive for meticillin-resistant Staphylococcus aureus (MRSA).

Results

The response rate was 38.4 % (163/425 patients). Approximately 75 % of the patients were interested in information on infection prevention and control. The topics of interest differed between the two patient groups: MRSA patients had a higher need for infection prevention and control information. TEP patients showed a high acceptance of antiseptic body wash and a willingness to pay for it themselves. Information given to patients should be group-specific and timely.

Conclusion

Our data suggest a lack of information on infection prevention and control among patients and underline the importance of patient empowerment. The willingness of patients to pay personally for antiseptic wash should be assessed further.

Staphylococcus aureus and Methicillin Resistant Staphylococcus aureus (MRSA) Carriage and Infections

Staphylococcus aureus is among the most common opportunistic infections worldwide, as it is found as part of the flora in many parts of the body. S. aureus is the leading cause of nosocomial infections with its ability to rapidly colonize the infected area, high virulence, rapid adaptation to environmental conditions, and the ability to develop very fast and effective resistance even to new generation antibiotics. Methicillin-resistant Staphylococcus aureus (MRSA), first identified in the 1960s, is one of the most successful modern pathogens, becoming an important factor in hospitals in the 1980s. MRSA is an important factor, especially in hospitalized patients and healthcare-associated infections. Patients colonized with S. aureus and MRSA are at risk for community-acquired infections. It is critical that multidrug resistance reduces treatment options in MRSA infections and MRSA strains. These microorganisms have been the subject of research for years as they spread and become resistant in both social and medical settings and cause great morbidity and mortality. With the rapid spread of resistance among bacteria, antibiotic resistance has increased the cost of health care, and this has become the factor limiting the production of new antibiotics.

Key predictors and burden of meticillin-resistant Staphylococcus aureus in comparison with meticillin-susceptible S. aureus infections in an Australian hospital setting

BACKGROUND

Staphylococcus aureus is associated with significant mortality and increased burden on the healthcare system. Relatively few reliable estimates are available regarding the impact of meticillin-resistant Staphylococcus aureus (MRSA) compared to meticillin-susceptible Staphylococcus aureus (MSSA) infections.

AIM

To compare patients with MRSA and MSSA infection to identify differences in inpatient mortality, length of stay and cost of hospital services, and identify predictors of MRSA as a cause of Staphylococcus aureus infection.

METHODS

An analytical, retrospective, longitudinal study using non-identifiable linked data on adults admitted to hospitals of a health district in Australia with a diagnosis of Staphylococcus aureus infection over a 10-year period. The main outcome measure was 30-day inpatient mortality. Secondary endpoints included total overnight stays, all-cause inpatient mortality, and hospitalisation cost within 1 year of index admission.

FINDINGS

Inpatient mortality at 30, 100, and 365 days was estimated to be significantly greater for patients with MRSA infections. The mean additional cost of MRSA infections when controlling for additional factors was $5,988 and 4 nights' additional hospital stay per patient within 1 year of index admission. Key predictors of MRSA infection were: date of index admission, higher comorbidity score, greater socio-economic disadvantage, admission to hospital other than via the emergency department, older age, and prior admission to hospital within 28-days of index admission.

CONCLUSIONS

MRSA infections are associated with increased inpatient mortality, cost and hospital length of stay, compared to those caused by MSSA. Efforts are required to alleviate the additional burden of MRSA infections on patients and healthcare systems.

Methicillin-Resistant Staphylococcus aureus Contamination of Frequently Touched Objects in Intensive Care Units: Potential Threat of Nosocomial Infections

Background

Bacterial contamination in intensive care units is an important risk factor associated with increasing incidences of nosocomial infections. This study was conducted to study the bacterial colonization on commonly touched objects of intensive care units and antibiotic resistance pattern of bacterial isolates.

Methods

This study was conducted in different intensive care units of Manipal Teaching Hospital, Pokhara, Nepal. A total of 235 swabs were collected from surfaces of bed rails, monitors, door handles, IV stands, telephone sets, nursing stations, medicine trolleys, sphygmomanometers, wash basin taps, dressing drums, stethoscopes, pulse oximeters, ventilators, defibrillators, and stretchers. Isolation, identification, and antibiotic susceptibility tests of the bacteria were performed following standard microbiological techniques.

Results

Of 235 samples, bacterial growth was observed in 152 samples. A total of 90 samples of Staphylococcus aureus were isolated from 235 samples. Most of the sampling sites included in this study were found contaminated with S. aureus. The highest number of S. aureus was cultured from the surface of bed rails. Of the total S. aureus isolates, 54.4% (49/90) were methicillin-resistant Staphylococcus aureus (MRSA). Vancomycin resistance was detected among 8.1% MRSA isolates (4/49). Acinetobacter species were the commonest Gram-negative bacterial isolate.

Conclusion

Bacterial contamination of the objects/instruments of the ICU was recorded to be high. The most common contaminating bacteria were S. aureus with a high percentage of MRSA and emergence of VRSA. Periodic microbiological surveillance, detection of contaminated sites, and effective decontamination methods would minimize the colonization by potential pathogens and their transmission.

Surgical Site Infection in Children with Neuromuscular Disorders after Laparoscopic Gastrostomy: A Propensity-Matched National Surgical Quality Improvement Program Pediatrics Database Analysis

Background: Prior studies have demonstrated that children with neuromuscular scoliosis have a higher incidence of infection after spine surgery. The purpose of the study is to determine whether children with neuromuscular disorders (NMDs) have higher rate of superficial surgical site infection (SSI) or increased hospital length of stay (LOS) compared with children without NMDs following laparoscopic gastrostomy creation, a common pediatric general surgery operation. Patients and Methods: We performed a retrospective propensity-matched analysis of laparoscopic gastrostomy creation in children from National Surgical Quality Improvement Program Pediatrics database (NSQIP-P) 2018-2019. Patients were stratified based on NMD status. We performed multivariable logistic regression and ordered logistic regression to estimate the odds ratio of superficial SSI within 30 days of surgery and increased LOS. Results: We screened 252,367 patients from the NSQIP-P 2018-2019 dataset. After applying inclusion and exclusion criteria and 1:1 propensity score-matching, there were 991 children with NMDs and 991 children without NMDs. Children with NMDs had higher prevalence of superficial SSI within 30 days of gastrostomy creation: 36 (3.63%) versus 18 (1.82%); p = 0.013. Children with NMDs had increased odds of having a superficial SSI within 30 days of laparoscopic gastrostomy tube (G-tube) placement compared with children without NMD (odds ratio [OR], 2.01; 95% confidence interval [CI], 1.13-3.58; p = 0.018). There was no difference in LOS based on NMD status. Conclusion: Children with NMDs have two-fold increased odds of superficial SSI after laparoscopic gastrostomy creation compared with children without NMDs. Children with NMDs should be the aim of targeted quality improvement initiatives to reduce infection risks.

The microbiology of diabetic foot infections: a meta-analysis

Background

Diabetic foot ulcers are a common complication of poorly controlled diabetes and often become infected, termed diabetic foot infection. There have been numerous studies of the microbiology of diabetic foot infection but no meta-analysis has provided a global overview of these data. This meta-analysis aimed to investigate the prevalence of bacteria isolated from diabetic foot infections using studies of any design which reported diabetic foot infection culture results.

Methods

The Medline, EMBASE, Web of Science and BIOSIS electronic databases were searched for studies published up to 2019 which contained microbiological culture results from at least 10 diabetic foot infection patients. Two authors independently assessed study eligibility and extracted the data. The main outcome was the prevalence of each bacterial genera or species.

Results

A total of 112 studies were included, representing 16,159 patients from which 22,198 microbial isolates were obtained. The organism most commonly identified was Staphylococcus aureus, of which 18.0% (95% CI 13.8–22.6%; I² = 93.8% [93.0–94.5%]) was MRSA. Other highly prevalent organisms were Pseudomonas spp., E. coli and Enterococcus spp. A correlation was identified between Gross National Income and the prevalence of Gram positive or negative organisms in diabetic foot infections.

Conclusion

The microbiology of diabetic foot infections is diverse, but S. aureus predominates. The correlation between the prevalence of Gram positive and negative organisms and Gross National Income could reflect differences in healthcare provision and sanitation. This meta-analysis has synthesised multiple datasets to provide a global overview of the microbiology of diabetic foot infections that will help direct the development of novel therapeutics.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-06516-7.

Prevalence of methicillin-resistant Staphylococcus aureus in Iranian children: a systematic review and meta-analysis

BACKGROUND

Antibiotic resistance is associated with longer hospitalizations, higher treatment costs, and increased morbidity and mortality rates.

PURPOSE

This study aimed to determine the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) in Iranian children.

METHODS

International databases, including Web of Science, PubMed, Embase, and Scopus, and Iranian databases, including Scientific Information Database (www.sid.ir), Magiran, and Iranian Database for Medical Literature (idml.research.ac.ir), were systematically searched for articles published between January 2000 and August 2019. Sources of heterogeneity were determined using subgroup analysis and meta-regression.

RESULTS

Overall, 343 studies were identified; of them, 20 were included in the meta-analysis to estimate the pooled prevalence. The pooled prevalence of MRSA was 42% (95% confidence interval [CI], 29-55) among culture-positive cases of S. aureus, 51% (95% CI, 39-62) in hospitalized children, and 14% (95% CI, 0.05-27) in healthy children.

CONCLUSION

The overall pooled prevalence of MRSA in children was 42%. Appropriate infection control measures and effective antibiotic therapy are needed.

EFFECTS OF KETAMINE IN METHICILLIN RESISTANT S. aureus AND IN SILICO INTERACTION WITH SORTASE A

Methicillin-resistant Staphylococcus aureus (MRSA) is one of the main human pathogens and is responsible for many diseases ranging from skin infections to more invasive infections. These infections are dangerous and expensive to treat because these strains are resistant to a large number of conventional antibiotics. Having said that, Antibacterial effect of ketamine against MRSA strains, its mechanism of action and in silico interaction with sortase A was evaluated. The antibacterial effect of ketamine was assessed by the broth microdilution method. Subsequently, the mechanism of action was assessed using flow cytometry and molecular docking assays with sortase A. Our results showed that Ketamine has a significant antibacterial activity against MRSA strains in the range of 2.49 to 3.73 mM. Their mechanism of action involves alterations in the membrane integrity and DNA damage, reducing cell viability that provoke death by apoptosis. In addition, Ketamine compound had affinity for S. aureus sortase A. These results indicate that this compound can be an alternative to develop new strategies to combat of infections caused by MRSA.

Fatores associados à infecção por Staphylococcus aureus resistente à meticilina em unidade de terapia intensiva

OBJECTIVE

To identify factors associated with methicillin-resistant Staphylococcus aureus (MRSA) infection in adult patients admitted to the Intensive Care Unit (ICU), and to compare them with a control group.

METHODS

Retrospective case-control study carried out in an adult ICU, from January 2015 to June 2017, with 61 patients who developed methicillin-resistant Staphylococcus aureus infection and the same number of control patients.

RESULTS

Most participants were male 65 (60.6%), with a neurological diagnosis 43 (35.2%) and hypertensive 61 (50.0%). In the comparison of the groups, there was a statistically significant difference in relation to mechanical ventilation (p=0.0107), tracheostomy (p=0.0083), death (p=0.0401), urinary catheter (p=0.0420), length of stay (p<0.0001) and severity (p=0.0003). The main factors associated with methicillin-resistant Staphylococcus aureus infection were: severity (OR= 65.69; CI=3.726-4.808; p=0.0018), use of antimicrobials (OR= 0.047;CI=0.028-0.122;p=0.0024), length of stay (OR=1.19; CI=0.952-1.031; p=0.0285).

CONCLUSION

methicillin-resistant Staphylococcus aureus infection is multifactorial and has been associated with length of stay and severity. Use of antimicrobials was a protective factor.

Implications of Methicillin-Resistant Staphylococcus aureus Carriage on Cardiac Surgical Outcomes

BACKGROUND

Staphylococcus aureus remains the most common cause of sternal surgical site infections (SSIs). Opinions on the postoperative implications of preoperative methicillin-resistant S aureus (MRSA) colonization currently differ. This study aimed to investigate whether MRSA carriage affects postoperative outcomes and safety of operation.

METHODS

A total of 1,774,811 cardiac surgical patients from 2009 to 2014 were identified from the National Inpatient Sample database. Among these patients, 5798 (0.33%) were MRSA carriers. Propensity-score matching was used to determine the effect of MRSA colonization on outcomes.

RESULTS

MRSA carriers did not differ in age or sex from noncarriers, but they more often presented for urgent surgery (P < .001). Among matched pairs, there was no difference in mortality (P = .76), stroke, SSIs, pneumonia, renal failure, cardiac complications, respiratory failure, or prolonged mechanical ventilation. MRSA infection (P < .001), MRSA septicemia (P = 0.03), and blood transfusion (P = .003) occurred more often among MRSA carriers. There was no increase in cost (P = .12), but the hospital length of stay was longer (P = .005). Predictors of MRSA infection among carriers included age older than 85 years, rural hospital location, and diabetes. Carriers with endocarditis and drug abuse were at highest risk for MRSA infection.

CONCLUSIONS

MRSA carriers undergoing cardiac surgery are not at higher risk for mortality or SSIs and can expect outcomes similar to those of noncarriers. Higher rates of postoperative MRSA infection and septicemia among carriers, although still very low, support the need for selective preoperative screening and prophylaxis when possible.

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.

Control of MSSA and MRSA in the United States: protocols, policies, risk adjustment and excuses

Data released by the U.S. Centers for Disease Control and Prevention (CDC) on March 5, 2019 showed that Staph aureus infections are a major problem in the United States, with 119,000 infections and almost 20,000 deaths in 2017. Rates of decline for hospital-onset MRSA have slowed since 2012 and the United States is not on track for meeting the 2015 U.S. Dept. of Health and Human Services’ goal of a 50% reduction by 2020. There is a need for improved standards for control of dangerous pathogens. Currently, the World Health Organization’s recommendation of preoperatively screening patients for Staph aureus has not become a standard of care in the United States.

The U.S. Veterans Health Administration also released data which found a much larger decrease in hospital-onset MRSA infections as opposed to hospital-onset MSSA using various infectious disease bundles that all included universal MRSA surveillance and isolation for MRSA carriers. These results mirror the results obtained by the United Kingdom’s National Health Service. These findings support the contention that the marked decline in hospital-onset MRSA infections observed in these studies is due to interventions which are specifically targeted towards MRSA.

A case is made that concerns with the integrity of healthcare policy research, along with industrial conflicts-of-interest have inhibited effective formulation of infectious disease policy in the United States. Because MRSA has become endemic in the general U.S. population (approximately 2%), the author advocates that universal facility-wide screening of MRSA on admission be included in infection prevention bundles used at U.S. hospital.

Development of predictive nomograms for clinical use to quantify the risk of isolating resistance prone organisms in patients with infected foot ulcers

Pseudomonas aeruginosa and methicillin-resistant Staphylococcus aureus (MRSA) have been considered prevalent pathogens in foot infections. However, whether empiric therapy directed against these organisms is necessary, and in whom to consider treatment, is rather unclear. The aim of this study was to develop predictive algorithms for forecasting the probability of isolating these organisms in the infected wounds of patients in a population where the prevalence of resistant pathogens is low. This was a retrospective study of regression model-based risk factor analysis that included 140 patients who presented with infected, culture positive foot ulcers to two urban hospitals. A total of 307 bacteria were identified, most frequently MRSA (11.1%). P. aeruginosa prevalence was 6.5%. In the multivariable analysis, amputation (odds ratio (OR) 5.75, 95% confidence interval (CI) 1.48-27.63), renal disease (OR 5.46, 95% CI 1.43-25.16) and gangrene (OR 2.78, 95% CI 0.82-9.59) were identified as risk factors associated with higher while diabetes (OR 0.07, 95% CI 0.01-0.34) and Infectious Diseases Society of America infection severity >3 (OR 0.18, 95% CI 0.03-0.65) were associated with lower odds of P. aeruginosa isolation (C statistic 0.81). Similar analysis for MRSA showed that amputation was associated with significantly lower (OR 0.29, 95% CI 0.09-0.79) risk, while history of MRSA infection (OR 5.63, 95% CI 1.56-20.63) and osteomyelitis (OR 2.523, 95% CI 1.00-6.79) was associated with higher odds of isolation (C statistic 0.69). We developed two predictive nomograms with reasonable to strong ability to discriminate between patients who were likely of being infected with P. aeruginosa or MRSA and those who were not. These analyses confirm the association of some, but also question the significance of other frequently described risk factors in predicting the isolation of these organisms.

Methicillin-Resistant Staphylococcus aureus and Other Multidrug-Resistant Colonizations/Infections in an Intensive Care Unit: Predictive Factors

INTRODUCTION AND OBJECTIVES

Methicillin-resistant Staphylococcus aureus (MRSA) is the most prevalent pathogen causing nosocomial infections in hospitals and health centers. This work is an effort to understand the epidemiology of MRSA and other multidrug-resistant pathogens in an intensive care unit (ICU) and to analyze characteristics that might determine the risk of MRSA colonization/infection in this unit.

METHOD

An observational, 1-year prospective longitudinal study was conducted to obtain information about MRSA and other multidrug-resistant colonizations/infections. The study was conducted with ICU patients with an artificial airway. Data were obtained from the National Study of the Control of Nosocomial Infections in Intensive Care Units database.

RESULTS

MRSA colonization was highly prevalent (33%); however, other pathogens like gram(-) Bacillus showed a higher infectious potency. Acute Physiology and Chronic Health Evaluation (APACHE-II) score >15 and hospital stay of >4 days were the main variables that significantly predicted the risk of developing MRSA colonization ( p < .001 in both cases). Moreover, the presence of MRSA increased the risk of developing a second multidrug-resistant colonization/infection, especially with methicillin-resistant Pseudomona.

DISCUSSION

The high prevalence of MRSA emphasizes the need to continue studying risk factors for MRSA colonization/infection, which may allow early identification of this pathogen. Therefore, we propose the use of the APACHE-II score and length of hospital stay to predict increased risk of MRSA colonization. Awareness of the heightened risk in particular patients could lead to early detection and prevention.

View point: gaps in the current guidelines for the prevention of Methicillin-resistant Staphylococcus aureus surgical site infections

The authors advocate the addition of two preventative strategies to the current United State’s guidelines for the prevention of surgical site infections. It is known that Staphylococcus aureus, including Methicillin-resistant Staphylococcus aureus (MRSA), carriers are at a higher risk for the development of infections and they can easily transmit the organism. The carriage rate of Staph. aureus in the general population approximates 33%. The CDC estimates the carriage rate of MRSA in the United States is approximately 2%. The first strategy is preoperative screening of surgical patients for Staph. aureus, including MRSA. This recommendation is based upon the growing literature which shows a benefit in both prevention of infections and guidance in preoperative antibiotic selection. The second is performing MRSA active surveillance screening on healthcare workers. The carriage rate of MRSA in healthcare workers approximates 5% and there are concerns of transmission of this pathogen to patients. MRSA decolonization of healthcare workers has been reported to approach a success rate of 90%. Healthcare workers colonized with dangerous pathogens, including MRSA, should be assigned to non-patient contact work areas. In addition, there needs to be implemented a safety net for both the worker’s economic security and healthcare. Finally, a reporting system for the healthcare worker acquisition and infections with dangerous pathogens needs to be implemented. These recommendations are needed because Staph. aureus including MRSA is endemic in the United States. Policies regarding endemic pathogens which are to be implemented only upon the occurrence of a facility defined “outbreak” have to be questioned, since absence of infections does not mean absence of transmission. Optimizing these policies will require further research but until then we should error on the side of patient safety.

Longitudinal Case Series of Staphylococcus aureus Colonization and Infection in Two Cohorts of Rural Iowans

OBJECTIVE

Examine the relationship between colonization with Staphylococcus aureus in the community and symptomatic infection in two cohorts of Iowans.

DESIGN

Case series within cohort study.

PARTICIPANTS

Rural Iowans selected from the Keokuk Rural Health Study, the Agricultural Health Study, and the Iowa Voter Registry.

METHODS

Longitudinal study within established cohorts evaluating documented S. aureus infections with samples available for molecular typing.

RESULTS

We examined this relationship in two cohorts of Iowans with a combined 11 incident cases of S. aureus SSTI, for which samples were available. Seven of the 11 individuals (63.6%) were colonized at baseline, in the nose (3/7, 42.9%), or in both the nose and throat (57.1%). All seven cases had matching sequence types between colonization and infection isolates.

CONCLUSIONS

Staphylococcus aureus causes millions of skin and soft tissue infections yearly. Although colonization with S. aureus is a frequent antecedent to infection, many studies investigating the link between colonization and infection have taken place in a clinical setting, particularly in urban hospitals. Our study has shown similar results in a rural community setting to those previously seen in clinics.