Risk Factors for Acquiring Vancomycin-Resistant Enterococcus and Methicillin-Resistant Staphylococcus aureus on a Burn Surgery Step-Down Unit:

Association of length of hospital stay, total body surface area burned, and Carbapenem-Resistant Klebsiella pneumoniae infection in burn patients: A retrospective study

BACKGROUND

The specific relationships between total body surface area burned (TBSA), length of stay (LOS), and carbapenem-resistant Klebsiella pneumoniae (CRKP) infection remain unclear. This study aimed to explore the relationship between TBSA and CRKP infection and to examine whether LOS mediates the association between TBSA and the risk of CRKP infection.

METHODS

We retrospectively collected the clinical data of adult burn patients admitted to Nanyang Nanshi Hospital between 2021 and 2023. We used multivariate logistic regression analysis to study the risk factors for CRKP infection; restricted cubic spline analysis to investigate the associations between TBSA, LOS, and CRKP infection; and mediation analysis to examine whether LOS mediated the association between TBSA and CRKP infection.

RESULTS

A total of 178 subjects were included in the study; 104 (58.4 %) were male, and the median age was 47 (33-59) years. Thirty-one (17.4 %) subjects developed CRKP infection. Both TBSA and LOS showed a linear positive correlation with the risk of CRKP infection. The LOS mediated the association between TBSA and incident CRKP infection, with a proportion of 17.6 %.

CONCLUSION

The risk of CRKP infection linearly increased as TBSA or LOS increased, and LOS mediated approximately 20 % of the total association between TBSA and CRKP infection.

Two-dimensional nanomaterials: A multifunctional approach for robust for diabetic wound repair

Diabetic wounds pose a clinical challenge due to persistent inflammation, severe bacterial infections, inadequate vascularization, and pronounced oxidative stress. Current therapeutic modalities fail to provide satisfactory outcomes in managing these conditions, resulting in considerable patient distress. Two-dimensional nanomaterials (2DNMs), characterized by their unique nanosheet structures, expansive surface areas, and remarkable physicochemical properties, have garnered considerable attention for their potential in therapeutic applications. Emerging 2DNMs can be loaded with various pharmacological agents, including small molecules, metal ions, and liposomes. Moreover, they can be integrated with various biomaterials such as hydrogels, microneedles, and microspheres, thus demonstrating unprecedented advantages in expediting the healing process of diabetic wounds. Moreover, 2DNMs exhibit exceptional performance characteristics, including high biocompatibility, effective antimicrobial properties, optimal phototherapeutic effects, and enhanced electrostimulation capabilities. These properties enable them to modulate the wound microenvironment, leading to widespread application in tissue repair with remarkable outcomes. This review delineates several emerging 2DNMs, such as graphene and its derivatives, black phosphorus, MXenes, and transition metal dichalcogenides, in the context of diabetic wound repair. Furthermore, it elucidates the translational challenges and future perspectives of 2DNMs in wound healing treatments. Overall, 2DNMs present a highly promising strategy for ameliorating diabetic wounds, thus providing novel avenues for diagnostic and therapeutic strategies in diabetic wound management.

Multidrug-Resistant Organisms: The Silent Plight of Burn Patients

The global increasing spread of multidrug-resistant organisms (MDROs) is threatening the control of various infections in vulnerable populations and patient groups. One of the most affected groups is patients with burns, who are prone to hyperinfection as they suffer from a hypermetabolic state and weaken immune barriers. Those patients also share the infection risk of patients hospitalized for a long time, including ventilator-associated pneumonia and urinary tract infections. While some preventative and therapeutic management styles are still controversial, we discuss consensuses here. In this review, we aim to present the current knowledge on multidrug resistance with a special focus on patients with burns, discuss various causative organisms and their treatment options, and highlight the importance of antibiotic stewardship and teamwork in responding to an outbreak of MDROs.

A Pilot Analysis for a Multicentric, Retrospective Study on Biodiversity and Difficult-to-Treat Pathogens in Burn Centers across the United States (MICROBE)

Following burn injury, patients are at increased risk of infection and are often cited as having a high incidence of difficult-to-treat pathogens (DTp). The purpose of this study is to determine the incidence of DTp after burn injury, which factors are associated with their development, and subsequent outcomes. This single-center, retrospective study assessed patients with thermal or inhalation injury who had a positive culture resulting in initiation of treatment (i.e., excision, topical, or systemic antimicrobials). Demographic data, pathogen and resistance profiles, and prior exposure to topical and systemic antimicrobials were collected. Pathogens were considered DTp if they were multi-drug-resistant (MDR), extensively drug-resistant (XDR), methicillin-resistant Staphylococcus aureus (MRSA), extended-spectrum beta-lactamase (ESBL)-producing, AmpC-producing, carbapenem-resistant, difficult-to-treat resistance (DTR) Pseudomonas sp., carbapenem-resistant Acinetobacter baumannii (CRAB), or Stenotrophomonas spp. Sixty-five patients who grew 376 pathogens were included in the final analysis. Two-hundred thirteen (56.7%) pathogens were considered DTp. Prior exposure to 7 of the 11 collected topical antimicrobials and 9 of 11 systemic antimicrobial classes were significantly associated with future development of a DTp. This remained true for six and eight, respectively, after controlling for significant covariates via logistic regression. As there were only four deaths, a Cox-proportional hazard analysis was not feasible. The Kaplan-Meier plot according to DTp revealed a clear divergence in mortality (Log rank p = 0.0583). In this analysis, exposure to topical and systemic antibiotics was associated with the development of DTp. The results from this pilot study will inform the next iteration of multicenter study.

Burn Infection and Burn Sepsis

Background: Infection is the most common complication and cause of death in patients suffering burn injuries. These patients are susceptible to infection and burn wound sepsis secondary to the alterations in their physiology. Diagnosis and management of infections rely on physical examination, cultures, and the pathology of the burn wound. Method: We performed an electronic search for articles in the Google Scholar and PubMed databases using the search terms "burn sepsis," "burn infection," and "burn critical care." Results: Multiple factors increase burn patients' risk of invasive infection and sepsis, including underlying factors and co-morbidities, the percent total body surface area of the burn, delays in burn wound excision, and microbial virulence/bacterial count. Organisms causing burn wound infection differ, depending on the time since injury and its location; and diagnosis is multi-factorial. The most common pathogens remain Staphylococcus and Pseudomonas spp. Conclusion: Overall, the recognition of burn sepsis is based on clinical findings. Treatment consists of a combination of local dressings, early burn excision, and systemic antimicrobial therapy. The mortality rate has decreased significantly over the past 10 years, but continued efforts at timely management and infection prevention are essential.

Management and prevention of drug resistant infections in burn patients

Introduction: Despite modern advances, the primary cause of death after burns remains infection and sepsis. A key factor in determining outcomes is colonization with multi-drug resistant (MDR) organisms. Infections secondary to MDR organisms are challenging due to lack of adequate antibiotic treatment, subsequently prolonging hospital stay and increasing risk of adverse outcomes. Areas covered: This review highlights the most frequent organisms colonizing burn wounds as well as the most common MDR bacterial infections. Additionally, we discuss different treatment modalities and MDR infection prevention strategies as their appropriate management would minimize morbidity and mortality in this population. We conducted a search for articles on PubMed, Web of Science, Embase, Cochrane, Scopus and UpToDate with applied search strategies including a combination of: "burns, 'thermal injury,' 'infections,' 'sepsis,' 'drug resistance,' and 'antimicrobials.' Expert opinion: Management and prevention of MDR infections in burns is an ongoing challenge. We highlight the importance of preventative over therapeutic strategies, which are easy to implement and cost-effective. Additionally, targeted, limited use of antimicrobials can be beneficial in burn patients. A promising future area of investigation within this field is post-trauma microbiome profiling. Currently, the best treatment strategy for MDR in burn patients is prevention.

Background Information: Isolation Routines

The isolation of patients with suspected or documented infections—to not spread to others—has been discussed for hundreds of years. Guidelines are many, methods are different, attitudes show vide variations, routines and procedures are still changing, regulations by law may be absent, and some healthcare professionals may be afraid of adverse outcomes of isolation [1–44]. Microbes that are spread in the environment, on the hands and equipment are invisible. The invisible agent does not call on attention before the infection; clinical disease, hospital infection or nosocomial infection is a factum that can be registered [23, 28, 29, 35–37]. How to stop the transmission is often “to believe and not believe” in infection control.

Bacterial Infections After Burn Injuries: Impact of Multidrug Resistance

Patients who are admitted to the hospital after sustaining a large burn injury are at high risk for developing hospital-associated infections. If patients survive the initial 72 hours after a burn injury, infections are the most common cause of death. Ventilator-associated pneumonia is the most important infection in this patient population. The risk of infections caused by multidrug-resistant bacterial pathogens increases with hospital length of stay in burn patients. In the first days of the postburn hospitalization, more susceptible, Gram-positive organisms predominate, whereas later more resistant Gram-negative organisms are found. These findings impact the choice of empiric antibiotics in critically ill burn patients. A proactive infection control approach is essential in burn units. Furthermore, a multidisciplinary approach to burn patients with a team that includes an infectious disease specialist and a pharmacist in addition to the burn surgeon is highly recommended.

Antimicrobial resistance patterns and virulence factors of enterococci isolates in hospitalized burn patients

OBJECTIVE

The objective of this study was to determine the frequency of the antimicrobial resistance and genes encoding virulence factors of enterococci isolated in hospitalized burn patients in a major burn center in Ahvaz, southwest of Iran. A total of 340 bacterial isolates were collected from the burn center from February 2014 to February 2015. The antimicrobial susceptibility and MIC of vancomycin were determined using the disk diffusion and micro-agar dilution techniques. The genus and species-specific genes, potential virulence genes, and vanA and vanB genes were detected by polymerase chain reaction.

RESULTS

According to our results, out of the 340 bacterial isolates, 16.4% (n = 56) were identified as enterococci. Out of the 56 enterococcal isolates, 35 (62.5%) were Enterococcus faecalis and 21 (37.5%) were Enterococcus faecium. More than 20% (n = 5) of E. faecium demonstrated resistance to vancomycin. The gelE and asa genes were the most prevalent virulence genes in E. faecalis (48.5%) and E. faecium (43%) isolates. The emergence of vancomycin resistant E. faecium strains which have several virulence factors should be considered as a major cause of concern for burn centers. Control and management of infections induced by enterococci should be regarded as highly important in burn patients.

Methicillin Resistant Staphylococcus aureus Transmission in a Ghanaian Burn Unit: The Importance of Active Surveillance in Resource-Limited Settings

Objectives:Staphylococcus aureus infections in burn patients can lead to serious complications and death. The frequency of S. aureus infection is high in low- and middle-income countries presumably due to limited resources, misuse of antibiotics and poor infection control. The objective of the present study was to apply population genomics to precisely define, for the first time, the transmission of antibiotic resistant S. aureus in a resource-limited setting in sub-Saharan Africa.

Methods:Staphylococcus aureus surveillance was performed amongst burn patients and healthcare workers during a 7-months survey within the burn unit of the Korle Bu Teaching Hospital in Ghana.

Results: Sixty-six S. aureus isolates (59 colonizing and 7 clinical) were obtained from 31 patients and 10 healthcare workers. Twenty-one of these isolates were ST250-IV methicillin-resistant S. aureus (MRSA). Notably, 25 (81%) of the 31 patients carried or were infected with S. aureus within 24 h of admission. Genome comparisons revealed six distinct S. aureus clones circulating in the burn unit, and demonstrated multiple transmission events between patients and healthcare workers. Further, the collected S. aureus isolates exhibited a wide range of genotypic resistances to antibiotics, including trimethoprim (21%), aminoglycosides (33%), oxacillin (33%), chloramphenicol (50%), tetracycline (59%) and fluoroquinolones (100%).

Conclusion: Population genomics uncovered multiple transmission events of S. aureus, especially MRSA, within the investigated burn unit. Our findings highlight lapses in infection control and prevention, and underscore the great importance of active surveillance to protect burn victims against multi-drug resistant pathogens in resource-limited settings.

Timeline of health care-associated infections and pathogens after burn injuries

BACKGROUND

Infections are an important cause of morbidity and mortality after burn injuries. Here, we describe the time line of infections and pathogens after burns.

METHODS

A retrospective study was performed in a large tertiary care burn center from 2004-2013. Analyses were performed on health care-associated infections (HAIs) meeting Centers for Disease Control and Prevention criteria and on all positive cultures. Incidence rates per 1,000 days were calculated for specific HAI categories and pathogens and across hospitalization time (week 1, weeks 2-3, and week ≥4).

RESULTS

Among 5,524 patients, the median burn size was 4% of total body surface area (interquartile range, 2%-10%). Of the patients, 7% developed an HAI, of whom 33% had >1 HAI episode. Gram-positive bacteria were isolated earlier, and gram-negative bacteria were isolated later during hospitalization. Of 1,788 bacterial isolates, 44% met criteria for multidrug resistance, and 23% met criteria for extensive drug resistance. Bacteria tended to become increasingly resistant to antibiotics as time from admission increased.

CONCLUSIONS

We observed differences in infection type, pathogen, and antibiotic-resistant bacterium risk across time of hospitalization. These results may guide infection prevention in various stages of the postburn admission.

Dissimilar Fitness Associated with Resistance to Fluoroquinolones Influences Clonal Dynamics of Various Multiresistant Bacteria

Fitness cost associated with resistance to fluoroquinolones was recently shown to vary across clones of methicillin-resistant Staphylococcus aureus and extended-spectrum β-lactamase-producing Klebsiella pneumoniae. The resulting dissimilar fitness should have influenced the clonal dynamics and thereby the rates of resistance for these pathogens. Moreover, a similar mechanism was recently proposed for the emergence of the H30 and H30R lineages of ESBL-producing E. coli and the major international clone (ribotype 027) of Clostridium difficile. Furthermore, several additional international clones of various multiresistant bacteria are suspect to have been selected by an analogous process. An ability to develop favorable mutations in the gyrase and topoisomerase IV genes seems to be a prerequisite for pathogens to retain fitness while showing high-level resistance to fluoroquinolones. Since, the consumption of other "non-fluoroquinolone" groups of antibiotics have also contributed to the rise in resistance rates a more judicious use of antibiotics in general and of fluoroquinolones in particular could ameliorate the international resistance situation.

Prevalence of vancomycin resistant Staphylococcus aureus (VRSA) in methicillin resistant S. aureus (MRSA) strains isolated from burn wound infections

OBJECTIVES

The increase in resistance of methicillin resistant Staphylococcus aureus (MRSA) strains to vancomycin has been perceived as a formidable threat in the therapeutic fields. The present study investigated the vancomycin resistance traits of MRSA isolates [vancomycin resistant S. aureus (VRSA)] collected from burn patients.

MATERIALS AND METHODS

Twenty-nine of 40 isolates of Staphylococcus spp. were identified as S. aureus which were further tested against 20 commercially available antibiotics to determine antibiotic susceptibility patterns.

RESULTS

Imipenem was the most potential antibiotic resulting in 90% sensitivity, followed by netilmicin, clindamycin, and nitrofurantoin (80% sensitivity). All isolates were found to be resistant to penicillin. Approximately 75% of them were found to be resistant to methicillin, oxacillin, azithromycin, cipro-floxacin, and tetracycline. Approximately 45% isolates exhibited resistance to amikacin, chloramphenicol, gentamycin, and tobramycin. Twenty-one of the 29 strains of S. aureus were MRSA, of which 11 were resistant to vancomycin when employing the disc diffusion method. However, when the broth micro-dilution procedure was used to measure the minimum inhibitory concentration (MIC) of vancomycin, eight isolates were resistant to vancomycin, six with an MIC of 32 μg/mL and two with an MIC of 64 μg/mL.

CONCLUSION

A significant fraction of VRSA was found among MRSA strains in this study, revealing the necessity for new and effective drugs against MRSA.

Virulence factors, antimicrobial resistance pattern and molecular analysis of Enterococcal strains isolated from burn patients

The enterococci are emerging as a significant cause of hospital acquired infections. The pathogenesis of enterococci is attributed to the production of virulence factors and resistance to antibiotics. The purpose of the study was to assess the prevalence of genes encoding virulence factor, antimicrobial resistance determinant and molecular characteristic of enterococci isolated from burn patients. A total of 57 enterococci isolated from wound specimens of patients with burn injury were characterized by phenotypic and genotypic methods. The efaA was the most frequently detected gene (100%), followed by ace (89.1%), asa1 (54.3%), gelE (50%), cylA (30.4%), esp (23.9%) and hyl (8.7%) among Enterococcus faecalis isolates. The Enterococcus faecium strains carried asa1 and ace genes. All isolates were susceptible to tigecycline and vancomycin. Inducible resistance to clindamycin was not observed and 64% of isolates had resistance to erythromycin. High-level gentamicin resistance (HLGR) was seen in 65.2% of E. faecalis strains. The aac(6')-Ie-aph(2″)-Ia gene was found in 47.8% of E. faecalis isolates. Our data indicated that the efaA, ace and asa1 were most frequent genes encoding virulence factors among Enterococci isolated from burn wound infection and the incidence of virulence factor genes was higher in E. faecalis rather than other isolates. The molecular analysis demonstrated high genetic diversity among Enterococcus populations from burn patients.

Risk factors for, and the effect of MRSA colonization on the clinical outcomes of severely burnt patients

BACKGROUND

MRSA is an on-going problem for burn patients.

AIM

To analyze risk factors for, and the effect of MRSA colonization on burn patients' outcome.

METHODS

During 21 months burn patients' details and MRSA isolates were analyzed, and a case-control study performed.

RESULTS

Of 357 burn patients, 57 (16%) tested positive for MRSA. Compared to the MRSA negative group, MRSA positive patients had a higher median total burn surface area (15%[IQR 5-17%] vs. 5%[IQR 2-8%]; p<0.001), more admissions to ICU (54% vs. 26%; p<0.001), longer ICU length of stay (4.3 vs. 1.0 days; p<0.001), required more operations (1.6 vs. 0.8; p<0.001), and had longer total hospital length of stay (25.5 vs. 8.0 days; p<0.001). MRSA positivity was a significant independent predictor of increased length of stay (6.0 days, 95%CI 2.39-9.6 days; p=0.001) in a multivariable regression model correcting for patients TBSA and co-morbidities. Cardiac comorbidities (OR 5.14, 95%CI 1.76-15.62; p<0.001) and a longer exposure to the hospital environment (OR 1.05, 95%CI 1.02-1.09, p=0.005) increased the likelihood for MRSA positivity.

CONCLUSION

The negative impact of MRSA positivity on burn patients outcome indicates the need for improved screening procedures for early identification and further efforts toward MRSA infection control to prevent cross-infection as this may significantly impair patients' outcome.

Has the use of fluoroquinolones facilitated the widespread dissemination of methicillin-resistant Staphylococcus aureus and extended-spectrum β-lactamase-producing Klebsiella pneumoniae in the healthcare setting?

Our group recently demonstrated that diverse fitness cost associated with resistance to fluoroquinolones allowed the extensive dissemination of the major international clones of both methicillin-resistant Staphylococcus aureus (MRSA) and multiresistant Klebsiella pneumoniae in the healthcare setting. The mechanism described by us was subsequently confirmed by British authors investigating the dynamics of MRSA clones in England. Our results imply that the use of fluoroquinolones should impact the incidence for both MRSA and multiresistant K. pneumoniae. A review of the related clinical studies mostly support this notion and shows that changes in the consumption of fluoroquinolone type antibiotics and the rates for both MRSA and multiresistant ESBL-producing K. pneumoniae remain usually in accordance. Though the association seems strong and the mechanism behind it unequivocal the use of fluoroquinolones should not be abandoned; a more judicious application can be recommended.

Confounding by indication affects antimicrobial risk factors for methicillin-resistant Staphylococcus aureus but not vancomycin-resistant enterococci acquisition

Background

Observational studies rarely account for confounding by indication, whereby empiric antibiotics initiated for signs and symptoms of infection prior to the diagnosis of infection are then viewed as risk factors for infection. We evaluated whether confounding by indication impacts antimicrobial risk factors for methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE) acquisition.

Findings

We previously reported several predictors of MRSA and VRE acquisition in 967 intensive care unit (ICU) patients with no prior history of MRSA or VRE who had an initial negative screening culture followed by either a subsequent negative screening culture (controls) or positive screening or clinical culture (cases). Within and prior to this acquisition interval, we collected demographic, comorbidity, daily device and antibiotic utilization data. We now re-evaluate all antibiotics by medical record review for evidence of treatment for signs and symptoms ultimately attributable to MRSA or VRE. Generalized linear mixed models are used to assess variables associated with MRSA or VRE acquisition, accounting for clustering by ward. We find that exclusion of empiric antibiotics given for suspected infection affects 17% (113/661) of antibiotic prescriptions in 25% (60/244) of MRSA-positive patients but only 1% (5/491) of antibiotic prescriptions in 1% (3/227) of VRE-positive patients. In multivariate testing, fluoroquinolones are no longer associated with MRSA acquisition, and aminoglycosides are significantly protective (OR = 0.3, CI:0.1-0.7).

Conclusions

Neglecting treatment indication may cause common empiric antibiotics to appear spuriously associated with MRSA acquisition. This effect is absent for VRE, likely because empiric therapy is infrequent given the low prevalence of VRE.

Risk factors for and epidemiology of community-onset vancomycin-resistant Enterococcus faecalis in southeast Michigan

BACKGROUND

Given the known link between vancomycin-resistant Enterococcus faecalis (VREF) and vancomycin-resistant Staphylococcus aureus (VRSA), the recent increase in prevalence of VREF in southeast Michigan has raised concerns about the presence of a large "community" reservoir of VREF. Efforts to control its spread face some important challenges.

METHODS

Patients with clinical isolates of community-onset (CO) VREF (cases) were compared with matched uninfected controls (study 1) and patients with hospital-onset (HO) VREF (study 2). Here, CO was defined as a hospital stay of ≤2 days before VRE isolation.

RESULTS

Independent predictors for the isolation of CO-VREF compared with uninfected controls were nonhome residence; chronic skin ulcers; previous invasive procedures/surgery; exposure to cephalosporin, penicillin, and/or vancomycin; immunosuppressive status; and the presence of indwelling devices. Independent predictors for isolation of CO-VREF compared with HO-VREF included no stay in an intensive care unit in the previous 3 months and recent hospitalization. VREF isolation from wounds and aminoglycoside exposure were inversely associated with isolation of CO-VREF.

CONCLUSIONS

Health care-related exposures and antimicrobial exposures are risk factors for the isolation of CO-VREF. Regional infection control practices are imperative in controlling CO-VREF, in addition to the emergence and spread of VRSA.

Antibiotic therapy for the treatment of methicillin-resistant Staphylococcus aureus (MRSA) in non surgical wounds

BACKGROUND

Non surgical wounds include chronic ulcers (pressure or decubitus ulcers, venous ulcers, diabetic ulcers, ischaemic ulcers), burns and traumatic wounds. The prevalence of methicillin-resistant Staphylococcus aureus (MRSA) colonisation (i.e. presence of MRSA in the absence of clinical features of infection such as redness or pus discharge) or infection in chronic ulcers varies between 7% and 30%. MRSA colonisation or infection of non surgical wounds can result in MRSA bacteraemia (infection of the blood) which is associated with a 30-day mortality of about 28% to 38% and a one-year mortality of about 55%. People with non surgical wounds colonised or infected with MRSA may be reservoirs of MRSA, so it is important to treat them, however, we do not know the optimal antibiotic regimen to use in these cases.

OBJECTIVES

To compare the benefits (such as decreased mortality and improved quality of life) and harms (such as adverse events related to antibiotic use) of all antibiotic treatments in people with non surgical wounds with established colonisation or infection caused by MRSA.

SEARCH METHODS

We searched the following databases: The Cochrane Wounds Group Specialised Register (searched 13 March 2013); The Cochrane Central Register of Controlled Trials (CENTRAL) (Issue 2); Database of Abstracts of Reviews of Effects (2013, Issue 2); NHS Economic Evaluation Database (2013, Issue 2); Ovid MEDLINE (1946 to February Week 4 2013); Ovid MEDLINE (In-Process & Other Non-Indexed Citations, March 12, 2013); Ovid EMBASE (1974 to 2013 Week 10); EBSCO CINAHL (1982 to 8 March 2013).

SELECTION CRITERIA

We included only randomised controlled trials (RCTs) comparing antibiotic treatment with no antibiotic treatment or with another antibiotic regimen for the treatment of MRSA-infected non surgical wounds. We included all relevant RCTs in the analysis, irrespective of language, publication status, publication year, or sample size.

DATA COLLECTION AND ANALYSIS

Two review authors independently identified the trials, and extracted data from the trial reports. We calculated the risk ratio (RR) with 95% confidence intervals (CI) for comparing the binary outcomes between the groups and planned to calculate the mean difference (MD) with 95% CI for comparing the continuous outcomes. We planned to perform the meta-analysis using both fixed-effect and random-effects models. We performed intention-to-treat analysis whenever possible.

MAIN RESULTS

We identified three trials that met the inclusion criteria for this review. In these, a total of 47 people with MRSA-positive diabetic foot infections were randomised to six different antibiotic regimens. While these trials included 925 people with multiple pathogens, they reported the information on outcomes for people with MRSA infections separately (MRSA prevalence: 5.1%). The only outcome reported for people with MRSA infection in these trials was the eradication of MRSA. The three trials did not report the review's primary outcomes (death and quality of life) and secondary outcomes (length of hospital stay, use of healthcare resources and time to complete wound healing). Two trials reported serious adverse events in people with infection due to any type of bacteria (i.e. not just MRSA infections), so the proportion of patients with serious adverse events was not available for MRSA-infected wounds. Overall, MRSA was eradicated in 31/47 (66%) of the people included in the three trials, but there were no significant differences in the proportion of people in whom MRSA was eradicated in any of the comparisons, as shown below.1. Daptomycin compared with vancomycin or semisynthetic penicillin: RR of MRSA eradication 1.13; 95% CI 0.56 to 2.25 (14 people).2. Ertapenem compared with piperacillin/tazobactam: RR of MRSA eradication 0.71; 95% CI 0.06 to 9.10 (10 people).3. Moxifloxacin compared with piperacillin/tazobactam followed by amoxycillin/clavulanate: RR of MRSA eradication 0.87; 95% CI 0.56 to 1.36 (23 people).

AUTHORS' CONCLUSIONS

We found no trials comparing the use of antibiotics with no antibiotic for treating MRSA-colonised non-surgical wounds and therefore can draw no conclusions for this population. In the trials that compared different antibiotics for treating MRSA-infected non surgical wounds, there was no evidence that any one antibiotic was better than the others. Further well-designed RCTs are necessary.

Molecular epidemiology of methicillin-resistant Staphylococcus aureus in a burn unit from Brazil

Methicillin-resistant Staphylococcus aureus (MRSA) poses a threat for patients in burn units. Studies that mix epidemiological designs with molecular typing may contribute to the development of strategies for MRSA control. We conducted a study including: molecular characterization of Staphylococcal Chromosome Cassette mecA (SCCmec), strain typing with pulsed field gel electrophoresis (PFGE) and detection of virulence genes, altogether with a case-case-control study that assessed risk factors for MRSA and for methicillin-susceptible S. aureus (MSSA), using S. aureus negative patients as controls. Strains were collected from clinical and surveillance cultures from October 2006 through March 2009. MRSA was isolated from 96 patients. Most isolates (94.8%) harbored SCCmec type III. SCCmec type IV was identified in isolates from four patients. In only one case it could be epidemiologically characterized as "community-associated". PFGE typing identified 36 coexisting MRSA clones. When compared to MSSA (38 isolates), MRSA isolates were more likely to harbor two virulence genes: tst and lukPV. Previous stay in other hospital and admission to Intensive Care Unit were independent risk factors for both MRSA and MSSA, while the number of burn wound excisions was significantly related with the former (OR=6.80, 95%CI=3.54-13.07). In conclusion, our study found polyclonal endemicity of MRSA in a burn unit, possibly related to importing of strains from other hospitals. Also, it pointed out to a role of surgical procedures in the dissemination of MRSA strains.

Nursing home characteristics associated with methicillin-resistant Staphylococcus aureus (MRSA) Burden and Transmission

BACKGROUND

MRSA prevalence in nursing homes often exceeds that in hospitals, but reasons for this are not well understood. We sought to measure MRSA burden in a large number of nursing homes and identify facility characteristics associated with high MRSA burden.

METHODS

We performed nasal swabs of residents from 26 nursing homes to measure MRSA importation and point prevalence, and estimate transmission. Using nursing home administrative data, we identified facility characteristics associated with MRSA point prevalence and estimated transmission risk in multivariate models.

RESULTS

We obtained 1,649 admission and 2,111 point prevalence swabs. Mean MRSA point prevalence was 24%, significantly higher than mean MRSA admission prevalence, 16%, (paired t-test, p<0.001), with a mean estimated MRSA transmission risk of 16%.In multivariate models, higher MRSA point prevalence was associated with higher admission prevalence (p=0.005) and higher proportions of residents with indwelling devices (p=0.01). Higher estimated MRSA transmission risk was associated with higher proportions of residents with diabetes (p=0.01) and lower levels of social engagement (p=0.03).

CONCLUSIONS

MRSA importation was a strong predictor of MRSA prevalence, but MRSA burden and transmission were also associated with nursing homes caring for more residents with chronic illnesses or indwelling devices. Frequent social interaction among residents appeared to be protective of MRSA transmission, suggesting that residents healthy enough to engage in group activities do not incur substantial risks of MRSA from social contact. Identifying characteristics of nursing homes at risk for high MRSA burden and transmission may allow facilities to tailor infection control policies and interventions to mitigate MRSA spread.

The epidemiology of methicillin-resistant Staphylococcus aureus on a burn trauma unit

OBJECTIVE

We assessed the frequency and relatedness of methicillin-resistant Staphylococcus aureus (MRSA) isolates to determine whether healthcare workers, the environment, or admitted patients could be a reservoir for MRSA on a burn trauma unit (BTU). We also assessed risk factors for MRSA colonization among BTU patients.

DESIGN

Prospective cohort study and surveillance for MRSA carriage.

SETTING

BTU of a Midwestern academic medical center.

PATIENTS AND PARTICIPANTS

Patients admitted to a BTU from February 2009 through January 2010 and healthcare workers on this unit during the same time period.

METHODS

Samples for MRSA culture were collected on admission from the nares and wounds of all BTU patients. We also had collected culture samples from the throat, axilla, antecubital fossa, groin, and perianal area of 12 patients per month. Samples collected from healthcare workers' nares and from environmental sites were cultured quarterly. MRSA isolates were typed by pulsed-field gel electrophoresis.

RESULTS

Of 144 patients, 24 (17%) carried MRSA in their nares on admission. Male sex (odds ratio [OR], 5.51; 95% confidence interval [95% CI], 1.25-24.30), admission for necrotizing fasciitis (OR, 7.66; 95% CI, 1.64-35.81), and MRSA colonization of a site other than the nares (OR, 23.40; 95% CI, 6.93-79.01) were independent predictors of MRSA nasal carriage. Cultures of samples collected from 4 healthcare workers and 4 environmental cultures had positive results. Two patients were colonized with strains that were indistinguishable from strains collected from a healthcare worker or the environment.

CONCLUSIONS

Patients were a major reservoir for MRSA. Infection control efforts should focus on preventing transmission of MRSA from patients who are MRSA carriers to other patients on the unit.

Risk factors for prolonged carriage of vancomycin-resistant Enterococcus faecium among patients in intensive care units: a case-control study

OBJECTIVES

The aim of this study was to identify the risk factors for prolonged carriage of vancomycin-resistant Enterococcus faecium (VREF) in intensive care units (ICUs).

METHODS

A retrospective case-control study was performed in the ICUs of a university hospital in Korea from September 2006 to July 2009. VREF carriage was identified through weekly active surveillance rectal cultures. Clinical characteristics and the risk factors for VREF acquisition were compared between cases with prolonged VREF carriage (≥ 5 weeks, n = 58) and controls with shorter VREF carriage (<3 weeks, n = 36) in a multivariate logistic regression model. The effect of vancomycin consumption on vancomycin-resistant enterococci (VRE) colonization pressure was investigated using time-series analysis with an autoregressive error model.

RESULTS

Out of a total of 6327 rectal swab cultures examined, 1915 (30.3%) specimens from 266 patients were positive for VREF. The weekly VRE colonization pressure ranged from 0.77% to 42.42%. Vancomycin use after VREF acquisition significantly increased VREF carriage (adjusted odds ratio = 4.09; 95% confidence interval = 1.32-12.65). The case group had higher in-hospital mortality than the control group [21 (36.2%) versus 4 (11.1%), P = 0.007]. Increment of VRE colonization pressure was significantly associated with vancomycin consumption of 1week before (i.e. time t - 1) (P = 0.0028) and moderately associated with that of the corresponding week (i.e. time t) (P = 0.0595).

CONCLUSIONS

Vancomycin use in patients with VREF colonization might prolong the duration of carriage. Restriction of vancomycin use should be strengthened in these patients through infection control measures.