Synergism between Medihoney and Rifampicin against Methicillin-Resistant Staphylococcus aureus (MRSA)

Skin and chronic wound infections caused by highly antibiotic resistant bacteria such as methicillin-resistant Staphylococcus aureus (MRSA) are an increasing and urgent health problem worldwide, particularly with sharp increases in obesity and diabetes. New Zealand manuka honey has potent broad-spectrum antimicrobial activity, has been shown to inhibit the growth of MRSA strains, and bacteria resistant to this honey have not been obtainable in the laboratory. Combinational treatment of chronic wounds with manuka honey and common antibiotics may offer a wide range of advantages including synergistic enhancement of the antibacterial activity, reduction of the effective dose of the antibiotic, and reduction of the risk of antibiotic resistance. The aim of this study was to investigate the effect of Medihoney in combination with the widely used antibiotic rifampicin on S. aureus. Using checkerboard microdilution assays, time-kill curve experiments and agar diffusion assays, we show a synergism between Medihoney and rifampicin against MRSA and clinical isolates of S. aureus. Furthermore, the Medihoney/rifampicin combination stopped the appearance of rifampicin-resistant S. aureus in vitro. Methylglyoxal (MGO), believed to be the major antibacterial compound in manuka honey, did not act synergistically with rifampicin and is therefore not the sole factor responsible for the synergistic effect of manuka honey with rifampicin. Our findings support the idea that a combination of honey and antibiotics may be an effective new antimicrobial therapy for chronic wound infections.     

耐甲氧西林金黄色葡萄球菌染色体盒的研究进展

耐甲氧西林金黄色葡萄球菌（MRSA）的产生是由甲氧西林敏感的金黄色葡萄球菌（MSSA）获得外源性的SCCmec所致。MRSA菌株可以产生一种新的青霉素结合蛋白PBP2a,PBP2a降低了与β-内酰胺类抗生素的亲合力,从而对β-内酰胺类抗生素产生耐药性。PBP2a由mecA基因编码,mecA基因存在于葡萄球菌盒式染色体（Staphylococcal cassette chromosome mec,SCCmec）中,SCCmec是一种可移动的遗传元件,该元件还携带除mecA基因外的其他抗菌药物的耐药基因,造成多重耐药（Multidrug-resistance,MDR）。SCCmec目前主要分为8型,其中又分为若干亚型。SCCmec的基因型与MRSA的流行背景有关,不同地区的SCCmec基因分型分布可能不同。     

Effects of Subinhibitory Concentrations of Ceftaroline on Methicillin-Resistant Staphylococcus aureus (MRSA) Biofilms

Ceftaroline (CPT) is a novel cephalosporin with in vitro activity against Staphylococcus aureus. Ceftaroline exhibits a level of binding affinity for PBPs in S. aureus including PBP2a of methicillin-resistant S. aureus (MRSA). The aims of this study were to investigate the morphological, physiological and molecular responses of MRSA clinical strains and MRSA biofilms to sub-MICs (1/4 and 1/16 MIC) of ceftaroline by using transmission, scanning and confocal microscopy. We have also used quantitative Real-Time PCR to study the effect of sub-MICs of ceftaroline on the expression of the staphylococcal icaA, agrA, sarA and sasF genes in MRSA biofilms. In one set of experiments, ceftaroline was able to inhibit biofilm formation in all strains tested at MIC, however, a strain dependent behavior in presence of sub-MICs of ceftaroline was shown. In a second set of experiments, destruction of preformed biofilms by addition of ceftaroline was evaluated. Ceftaroline was able to inhibit biofilm formation at MIC in all strains tested but not at the sub-MICs. Destruction of preformed biofilms was strain dependent because the biofilm formed by a matrix-producing strain was resistant to a challenge with ceftaroline at MIC, whereas in other strains the biofilm was sensitive. At sub-MICs, the impact of ceftaroline on expression of virulence genes was strain-dependent at 1/4 MIC and no correlation between ceftaroline-enhanced biofilm formation and gene regulation was established at 1/16 MIC. Our findings suggest that sub-MICs of ceftaroline enhance bacterial attachment and biofilm formation by some, but not all, MRSA strains and, therefore, stress the importance of maintaining effective bactericidal concentrations of ceftaroline to fight biofilm-MRSA related infections.     

Potent In Vitro Bactericidal Activity of Polymyxin B against Methicillin-Resistant Staphylococcus aureus (MRSA)

Eradication of methicillin-resistant Staphylococcus aureus (MRSA) carried by inpatients or healthy hospital personnel by topical use of antibiotics is an important step for preventing outbreak of MRSA nosocomial infection. In the screening of the antibiotic best suited for this purpose, we have found that polymyxin B, a commonly used antibiotic for gram-negative infection, had an unexpected strong cytokilling activity towards MRSA clinical strains, which was more potent than that of vancomycin or gentamicin. The data suggested that polymyxin B could be an antibiotic of choice in the treatment of topical carriage of or infection caused by MRSA.     

耐甲氧西林金黄色葡萄球菌的分子流行病学研究

了解我院患者耐甲氧西林金黄色葡萄球菌（MRSA）的分子流行病学特点,为临床抗感染治疗提供依据。收集2007年1月~2008年9月我院分离的耐甲氧西林金黄色葡萄球菌共54株,采用PCR进行SCCmec基因分型、葡萄球菌A蛋白（SPA）分型,并检测杀白细胞毒素（PVL）基因,同时应用脉冲场凝胶电泳（PFGE）进行同源性分析。54株MRSA菌株SCCmec基因分型为SCCmecⅡ型17株,SCCmecⅢ型33株,SCCmecⅣ型2株,SCCmecⅤ型2株;SPA基因分型将28株归属为t030,9株为t002,8株为t037,5株为t570,2株为t437,t163和t796各1株;PVL毒素检测只有2株SCCmecⅣ型菌株阳性;PFGE证实院内MRSA感染主要为2种克隆株传播,同时还有其他型别出现。本院MRSA流行传播的SCCmec基因型主要以Ⅲ型占优势,同时发现有携带PVL毒素的CA-MRSA分离株流行,应引起密切关注。     

Livestock-Associated Methicillin-Resistant Staphylococcus aureus (MRSA) as Causes of Human Infection and Colonization in Germany

Pigs, cattle and poultry are colonized with MRSA and the zoonotic transmission of such MRSA to humans via direct animal contact, environmental contaminations or meat are a matter of concern. Livestock-associated (LA) MRSA are mostly belonging to clonal complex (CC) 398 as defined by multilocus sequence typing. However, MRSA of other clonal lineages including CC5, CC9 and CC97 have also been detected in livestock animals in Germany. Within the framework of a Dutch-German network project (EUREGIO), 14,036 MRSA isolated from clinical and screening specimens (January 2008 - June 2012) derived from human patients in hospitals as well as general or specialized practices in a German region characterized by a high density of livestock production, were subjected to S. aureus protein A (spa) sequence typing. The prevalence of putative LA-MRSA among the human MRSA isolates was determined by analyzing the detection of livestock-indicator (LI) spa types which had already been reported in German livestock. Overall, 578 spa types were detected among the MRSA isolates. LI spa types t011, t034, t108, t1451, t2011, t571, t1456, t1250, t1255, t1580, t2970, t2346, t1344, t2576, t2330 and t2510 (all of which are indicative for LA-MRSA CC398) accounted for 18.6% of all human isolates. The LI spa types t1430 (CC9), t3992 (CC97), t002 (CC5) and t007 (CC30) were found in 0.14%, 0.01%, 1.01% and 0.04% of all human MRSA isolates, respectively. LI spa types associated with CC398 represented 23% of all MRSA from screening samples and a varying proportion among isolates from clinical specimens ranging between 0% in cerebrospinal fluid, 8% in blood cultures and 14% in deep respiratory fluids. Our findings indicate that LA-MRSA are a major cause for human infection and stress the need for close surveillance. Although LA-MRSA CC398 predominates, the occurrence of putative LA-MRSA from other clonal lineages should be monitored.     

Effectiveness of Hospital-Wide Methicillin-Resistant Staphylococcus aureus (MRSA) Infection Control Policies Differs by Ward Specialty

Methicillin-resistant Staphylococcus aureus (MRSA) is a major cause of preventable nosocomial infections and is endemic in hospitals worldwide. The effectiveness of infection control policies varies significantly across hospital settings. The impact of the hospital context towards the rate of nosocomial MRSA infections and the success of infection control is understudied. We conducted a modelling study to evaluate several infection control policies in surgical, intensive care, and medical ward specialties, each with distinct ward conditions and policies, of a tertiary public hospital in Sydney, Australia. We reconfirm hand hygiene as the most successful policy and find it to be necessary for the success of other policies. Active screening for MRSA, patient isolation in single-bed rooms, and additional staffing were found to be less effective. Across these ward specialties, MRSA transmission risk varied by 13% and reductions in the prevalence and nosocomial incidence rate of MRSA due to infection control policies varied by up to 45%. Different levels of infection control were required to reduce and control nosocomial MRSA infections for each ward specialty. Infection control policies and policy targets should be specific for the ward and context of the hospital. The model we developed is generic and can be calibrated to represent different ward settings and pathogens transmitted between patients indirectly through health care workers. This can aid the timely and cost effective design of synergistic and context specific infection control policies.     

Comparison of Two Commercial PCR Methods for Methicillin-Resistant Staphylococcus aureus (MRSA) Screening in a Tertiary Care Hospital

Nose/throat-swabs from 1049 patients were screened for MRSA using CHROMagar MRSA, LightCycler Advanced MRSA, and Detect-Ready MRSA. Results were compared to the CHROMagar MRSA results, which was set as reference system. MRSA was detected in 3.05% of the patients with CHROMagar MRSA. LightCycler MRSA Advanced showed a higher clinical sensitivity (84.38%) than Detect-Ready MRSA (57.69%).The negative predictive values were high for both tests (>98%). The specificity and the positive predictive value were higher for the Detect-Ready MRSA test than for the LightCycler MRSA test (99.59% and 78.95% versus 98.52% and 64.29%). For routine screening LightCycler MRSA Advanced proved to be more efficient in our clinical setting as the clinical sensitivity was much higher than the sensitivity of Detect-Ready MRSA. CHROMagar MRSA detected more MRSA positive samples than both PCR methods, leading to the conclusion that the combination of PCR with cultural screening is still the most reliable way for the detection of MRSA. LightCycler MRSA Advanced was faster and needed less hands-on time. The advantage of Detect-Ready MRSA was the additional identification of methicillin-sensitive S.aureus (here in 34.63% of the samples), an information which can be possibly used for reducing the risk of postoperative infections in surgical patients in future.     

In-Silico Repurposing of Anticancer Drug (5-FU) as an Antimicrobial Agent Against Methicillin-Resistant Staphylococcus aureus (MRSA)

International Journal of Peptide Research and Therapeutics - The Centers for Disease Control and Prevention (CDC) reported earlier that more than 11,000 people died from a methicillin-resistant...     

Diversity of Methicillin-Resistant Staphylococcus aureus (MRSA) Strains Isolated from Inpatients of 30 Hospitals in Orange County,California

There is a need for a regional assessment of the frequency and diversity of MRSA to determine major circulating clones and the extent to which community and healthcare MRSA reservoirs have mixed. We conducted a prospective cohort study of inpatients in Orange County, California, systematically collecting clinical MRSA isolates from 30 hospitals, to assess MRSA diversity and distribution. All isolates were characterized by spa typing, with selective PFGE and MLST to relate spa types with major MRSA clones. We collected 2,246 MRSA isolates from hospital inpatients. This translated to 91/10,000 inpatients with MRSA and an Orange County population estimate of MRSA inpatient clinical cultures of 86/100,000 people. spa type genetic diversity was heterogeneous between hospitals, and relatively high overall (72%). USA300 (t008/ST8), USA100 (t002/ST5) and a previously reported USA100 variant (t242/ST5) were the dominant clones across all Orange County hospitals, representing 83% of isolates. Fifteen hospitals isolated more t008 (USA300) isolates than t002/242 (USA100) isolates, and 12 hospitals isolated more t242 isolates than t002 isolates. The majority of isolates were imported into hospitals. Community-based infection control strategies may still be helpful in stemming the influx of traditionally community-associated strains, particularly USA300, into the healthcare setting.     

Serum Stable and Low Hemolytic Temporin-SHa Peptide Analogs Disrupt Cell Membrane of Methicillin-Resistant Staphylococcus aureus (MRSA)

Probiotics and Antimicrobial Proteins - Anti-microbial peptides (AMPs) have attracted major attention due to their potential bio-activities against some multidrug resistant pathogens. The present...     

Phenol Soluble Modulin (PSM) Variants of Community-Associated Methicillin-Resistant Staphylococcus aureus (MRSA) Captured Using Mass Spectrometry-Based Molecular Networking

Molecular genetic analysis indicates that the problematic human bacterial pathogen methicillin-resistant Staphylococcus aureus possesses more than 2000 open reading frames in its genome. This number of potential gene products, coupled with intrinsic mechanisms of posttranslational modification, endows methicillin-resistant Staphylococcus aureus with a highly complex biochemical repertoire. Recent proteomic and metabolomic advances have provided methodologies to better understand and characterize the biosynthetic factors released by microbial organisms. Here, the emerging tool of mass spectrometry-based molecular networking was used to visualize and map the repertoire of biosynthetic factors produced by a community-associated methicillin-resistant Staphylococcus aureus strain representative of the epidemic USA300 clone. In particular, the study focused on elucidating the complexity of the recently discovered phenol soluble modulin family of peptides when placed under various antibiotic treatment stresses. Novel PSM truncated variant peptides were captured, and the type of variants that were clustered by the molecular networks platform changed in response to the different antibiotic treatment conditions. After discovery, a group of the peptides were selected for functional analysis in vitro. The peptides displayed bioactive properties including the ability to induce proinflammatory responses in human THP-1 monocytes. Additionally, the tested peptides did not display antimicrobial activity as previously reported for other phenol soluble modulin truncated variants. Our findings reveal that the PSM family of peptides are quite structurally diverse, and suggest a single phenol soluble modulin parent peptide can functionally spawn differential bioactivities in response to various external stimuli.A significant percentage of the human population harbors Staphylococcus aureus as a natural resident of their microbial flora (1). In non-infected individuals, S. aureus maintains a homeostatic coexistence with neighboring microbes and with the host (2). However, when equilibrium is disrupted, S. aureus is capable of establishing diseases ranging from minor superficial infections to potentially life-threatening invasive conditions (3, 4). Through the discovery and administration of antibiotics, clinicians have significantly reduced the morbidity and mortality associated with S. aureus (5, 6). In recent years, the consequences of persistent antibiotic exposure have become increasingly manifest through the emergence of resistant strains, including those left unperturbed by methicillin and related β-lactam antibiotics (MRSA)¹ or those with intermediate or full resistance to vancomycin (VISA/VRSA) (7). Certain drug-resistant S. aureus strains, such as the USA300 clone, have spread beyond the hospital setting and into the community, producing serious infections even in previously healthy individuals (8, 9). Both community-associated (CA) and hospital-associated (HA) multi-drug resistant S. aureus are highly evolved, multifaceted pathogens that pose an increasing threat to the health of not only our own, but future generations as well.The pathogenic mechanisms of S. aureus have been examined extensively through different stages of infection (10, 11), with an improved understanding of specific functions that various staphylococcal components contribute to virulence (12). The ability to outcompete other microflora for colonization, or to circumvent the host immune response during infectious spread, largely reflects a complex network of proteins and non-protein molecules that S. aureus secretes into its surroundings-which may collectively be termed biosynthetic release factors. One component of this network is the newly studied and multifunctional phenol soluble modulin (PSM) family of peptides. Associated with biofilm formation and possessing bioactivity toward host cells, PSMs are produced more abundantly by CA-MRSA compared with HA-MRSA strains (13, 14). PSMs are biosynthesized and released with formylated initiator methionine, allowing binding and activation of host neutrophils via the formyl peptide receptor 2 (FPR2) (15). A number of PSMs show cytolytic properties toward host cell lines, and supporting this, isogenic PSM-knockout mutants have decreased virulence in murine models of invasive infection (13). Recently, it was found that many in vitro PSMs phenotypes (e.g. neutrophil lysis, FPR2 binding) were strongly inhibited by serum lipoproteins (16). The same study showed up-regulation of PSM biosynthesis following phagocytosis, suggesting an important role in intracellular survival. Additionally, N-terminal truncated derivative forms of PSMs (dPSMs) with antibacterial properties were identified (17, 18). The finding that dPSMs possess antibacterial activities that are absent in the corresponding full-length parent PSMs, inspired a hypothesis that dPSMs endow CA-MRSA strains with a competitive advantage against resident microbiota upon colonizing host epithelia (i.e. once truncated PSMs gain antimicrobial properties).The invaluable tool of MS has played a major role in characterizing biosynthetic release factors for a diverse number of organisms (19). Over the past decade, the field has spawned several innovative methods to optimize data collection, processing, and organization. The advancement of MS processing methods has improved the capabilities for extracting significant information regarding an organism''s biochemical repertoire. One emerging tool to study biosynthetic release factor potential is the tandem MS data processing program, Spectral Networks. In conjunction with Cytoscape graphical mapping, Spectral Networks allows for the construction of a molecular network map that gives a visualization of tandem mass spectra grouping, based on similar scoring of overlapping ion fragmentation patterns (20, 21). The matching of spectra, termed spectral pairing, is unlike the conventional mode of processing MS data by matching against a reference library or specifying specific posttranslational modifications for identification (22). Instead, within a molecular network map, ion fragmentation patterns can be represented by correlation points, displayed as circular nodes, connected with a straight line to other nodes containing high similarity scores. The power of molecular networking is the information provided on tandem MS subpopulation clusters, which represent structurally matching but variant protein or non-protein biosynthetic release factors.In this work, the MS-based molecular networking platform was applied to a representative strain of the epidemic CA-MRSA USA300 clone. The study sought to provide insight into the biosynthetic release factor map of this pre-eminent human bacterial pathogen under normal growth and antibiotic challenged conditions. Biologically relevant pharmacological stimuli studied included sub-inhibitory concentrations of commonly prescribed commercial antibiotics as well as the innate human defense peptide LL-37 (23–25). In particular, our study goal was to monitor any variations in the type of dPSMs clustered within the molecular network map in response to these stimuli. We show an enriched extract derived from CA-MRSA alone or under these specific challenge conditions provides a highly complex biosynthetic release factor map. Analysis of subpopulation node clusters associated with PSMs prompted the discovery of several previously unreported α, β, and γ type dPSMs. The antibiotic stimuli modulated the type of dPSMs clustered, allowing for differential subclusters to be visualized that were absent in the untreated sample; including nodes that did not sequence to proteogenic PSMs. A group of the newly discovered PSM variants were assessed for functional properties and showed the induction of proinflammatory responses in THP-1 cells. In addition, in contrast to previous reports (17, 18), the tested dPSMs did not display antimicrobial activity. We conclude MS-based molecular networking can be used as a targeted discovery tool with the ability to identify previously unreported bioactive peptides.     

Nasal Colonization of Humans with Methicillin-Resistant Staphylococcus aureus (MRSA) CC398 with and without Exposure to Pigs

Background

Studies in several European countries and in North America revealed a frequent nasal colonization of livestock with MRSA CC398 and also in humans with direct professional exposure to colonized animals. The study presented here addresses the question of further transmission to non exposed humans.

Methods

After selecting 47 farms with colonized pigs in different regions of Germany we sampled the nares of 113 humans working daily with pigs and of their 116 non exposed family members. The same was performed in 18 veterinarians attending pig farms and in 44 of their non exposed family members. For investigating transmission beyond families we samples the nares of 462 pupils attending a secondary school in a high density pig farming area. MRSA were detected by direct culture on selective agar. The isolates were typed by means of spa-sequence typing and classification of SCCmec elements. For attribution of spa sequence types to clonal lineages as defined by multi locus sequence typing we used the BURP algorithm. Antibiotic susceptibility testing was performed by microbroth dilution assay.

Results

At the farms investigated 86% of humans exposed and only 4.3% of their family members were found to carry MRSA exhibiting spa-types corresponding to clonal complex CC398. Nasal colonization was also found in 45% of veterinarians caring for pig farms and in 9% of their non exposed family members. Multivariate analysis revealed that antibiotic usage prior to sampling beard no risk with respect to colonization. From 462 pupils only 3 were found colonized, all 3 were living on pig farms.

Conclusion

These results indicate that so far the dissemination of MRSA CC398 to non exposed humans is infrequent and probably does not reach beyond familial communities.     

Isolation,Identification, and Characterization of a Novel Bacteriocin Produced by Brevibacillus laterosporus DS-3 Against Methicillin-Resistant Staphylococcus aureus (MRSA)

Isolation and characterization of a bacteriocin from Brevibacillus laterosporus DS-3 and its ability in producing antibacterial activity were examined in t     

Atomoxetine Effects on Executive Function as Measured by the BRIEF-A in Young Adults with ADHD: A Randomized,Double-Blind,Placebo-Controlled Study

Objective

To evaluate the effect of atomoxetine treatment on executive functions in young adults with attention-deficit/hyperactivity disorder (ADHD).

Methods

In this Phase 4, multi-center, double-blind, placebo-controlled trial, young adults (18–30 years) with ADHD were randomized to receive atomoxetine (20–50 mg BID, N = 220) or placebo (N = 225) for 12 weeks. The Behavior Rating Inventory of Executive Function-Adult (BRIEF-A) consists of 75 self-report items within 9 nonoverlapping clinical scales measuring various aspects of executive functioning. Mean changes from baseline to 12-week endpoint on the BRIEF-A were analyzed using an ANCOVA model (terms: baseline score, treatment, and investigator).

Results

At baseline, there were no significant treatment group differences in the percentage of patients with BRIEF-A composite or index T-scores ≥60 (p>.5), with over 92% of patients having composite scores ≥60 (≥60 deemed clinically meaningful for these analyses). At endpoint, statistically significantly greater mean reductions were seen in the atomoxetine versus placebo group for the BRIEF-A Global Executive Composite (GEC), Behavioral Regulation Index (BRI), and Metacognitive Index (MI) scores, as well as the Inhibit, Self-Monitor, Working Memory, Plan/Organize and Task Monitor subscale scores (p<.05), with decreases in scores signifying improvements in executive functioning. Changes in the BRIEF-A Initiate (p = .051), Organization of Materials (p = .051), Shift (p = .090), and Emotional Control (p = .219) subscale scores were not statistically significant. In addition, the validity scales: Inconsistency (p = .644), Infrequency (p = .097), and Negativity (p = .456) were not statistically significant, showing scale validity.

Conclusion

Statistically significantly greater improvement in executive function was observed in young adults with ADHD in the atomoxetine versus placebo group as measured by changes in the BRIEF-A scales.

Trial Registration

ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT00510276","term_id":"NCT00510276"}}NCT00510276     

Extensive Dissemination of Methicillin-Resistant Staphylococcus aureus (MRSA) between the Hospital and the Community in a Country with a High Prevalence of Nosocomial MRSA

According to the EARS-Net surveillance data, Portugal has the highest prevalence of nosocomial methicillin-resistant Staphylococcus aureus (MRSA) in Europe, but the information on MRSA in the community is very scarce and the links between the hospital and community are not known. In this study we aimed to understand the events associated to the recent sharp increase in MRSA frequency in Portugal and to evaluate how this has shaped MRSA epidemiology in the community. With this purpose, 180 nosocomial MRSA isolates recovered from infection in two time periods and 14 MRSA isolates recovered from 89 samples of skin and soft tissue infections (SSTI) were analyzed by pulsed-field gel electrophoresis (PFGE), staphylococcal chromosome cassette mec (SCCmec) typing, spa typing and multilocus sequence typing (MLST). All isolates were also screened for the presence of Panton Valentine leukocidin (PVL) and arginine catabolic mobile element (ACME) by PCR. The results showed that ST22-IVh, accounting for 72% of the nosocomial isolates, was the major clone circulating in the hospital in 2010, having replaced two previous dominant clones in 1993, the Iberian (ST247-I) and Portuguese (ST239-III variant) clones. Moreover in 2010, three clones belonging to CC5 (ST105-II, ST125-IVc and ST5-IVc) accounted for 20% of the isolates and may represent the beginning of new waves of MRSA in this hospital. Interestingly, more than half of the MRSA isolates (8/14) causing SSTI in people attending healthcare centers in Portugal belonged to the most predominant clones found in the hospital, namely ST22-IVh (n = 4), ST5-IVc (n = 2) and ST105-II (n = 1). Other clones found included ST5-V (n = 6) and ST8-VI (n = 1). None of the MRSA isolates carried PVL and only five isolates (ST5-V-t179) carried ACME type II. The emergence and spread of EMRSA-15 may be associated to the observed increase in MRSA frequency in the hospital and the consequent spillover of MRSA into the community.     

Cost Analysis of an Intervention to Prevent Methicillin-Resistant Staphylococcus Aureus (MRSA) Transmission

Introduction

Our objective was to assess the cost implications of a vertical MRSA prevention program that led to a reduction in MRSA bacteremia.

Methods

We performed a matched historical cohort study and cost analysis in a single hospital in Israel for the years 2005-2011. The cost of MRSA bacteremia was calculated as total hospital cost for patients admitted with bacteremia and for patients with hospital-acquired bacteremia, the difference in cost compared to matched controls. The cost of prevention was calculated as the sum of the cost of microbiology tests, single-use equipment used for patients in isolation, and infection control personnel.

Results

An average of 20,000 patients were screened yearly. The cost of prevention was $208,100 per year, with the major contributor being laboratory cost. We calculated that our intervention averted 34 cases of bacteremia yearly: 17 presenting on admission and 17 acquired in the hospital. The average cost of a case admitted with bacteremia was $14,500, and the net cost attributable to nosocomial bacteremia was $9,400. Antibiotics contributed only 0.4% of the total disease management cost. When the annual cost of averted cases of bacteremia and that of prevention were compared, the intervention resulted in annual cost savings of $199,600.

Conclusions

A vertical MRSA prevention program targeted at high-risk patients, which was highly effective in preventing bacteremia, is cost saving. These results suggest that allocating resources to targeted prevention efforts might be beneficial even in a single institution in a high incidence country.