Development of mupirocin resistance among methicillin-resistant Staphylococcus aureus after widespread use of nasal mupirocin ointment

Nasal decolonization: What antimicrobials and antiseptics are most effective before surgery and in the ICU

BACKGROUND

Staphylococcus aureus colonization is a key risk factor for S. aureus infections in surgical patients and in hospitalized patients. Many studies have assessed various decolonization agents, protocols, and settings. This review summarizes key findings about nasal decolonization for 2 different patient populations: patients undergoing surgery and patients hospitalized in intensive care units.

METHODS

We reviewed major studies related to decolonization of patients colonized with S. aureus and who were either undergoing surgical procedures or were hospitalized in intensive care units. We focused on recent studies, particularly randomized controlled trials and robust quasi-experimental trials. We also reviewed select non-randomized trials when more rigorous trials were limited.

DISCUSSION/CONCLUSIONS

Mupirocin is the best-studied agent for decolonization. Its use reduces the risk of surgical site infection following orthopedic surgery (strongest data) and cardiac surgery. Mupirocin decolonization also reduces the incidence of S. aureus clinical cultures in the intensive care unit. Povidone-iodine is less well-studied. Current data suggest that it decreases the risk of surgical site infections after orthopedic surgical procedures. In contrast, povidone-iodine is less effective than mupirocin for reducing the incidence of S aureus clinical cultures in the intensive care unit. Both mupirocin and povidone-iodine have important limitations, highlighting the need for future decolonization research.

A Novel Protocol for Nasal Decolonization Using Prolonged Application of an Alcohol-Based Nasal Antiseptic Reduces Surgical Site Infections in Total Joint Arthroplasty Patients: A Retrospective Cohort Study

Background: Current nasal decolonization strategies utilize pre-operative agents without consideration for short-term re-colonization or de novo colonization. Many strategies utilize an antibiotic-based agent, raising concerns of limited gram-negative antimicrobial coverage and the emergence of resistant bacterial strains. This study evaluated the clinical utility of a non-antibiotic, alcohol-based nasal decolonization agent in decreasing surgical site infection (SSI) rates after total joint arthroplasty. Patients and Methods: We retrospectively compared an 18-month cohort of elective primary total joint arthroplasty patients treated peri-operatively with an alcohol-based sanitizer to historical controls. The alcohol-based agent was administered pre-operatively the day of surgery and for two weeks after surgery. Patients were followed for 90 days and assessed for signs or symptoms of SSI. Patient and caregiver compliance was recorded. There were 779 patients included in the experimental group and 647 included in the historical control group. Results: Patients receiving alcohol-based nasal decolonization had a lower rate of SSI compared with controls not receiving nasal decolonization (0.64% [5/779] vs. 1.55% [10/647]; p = 0.048; odds ratio, 2.43). Utilization of an alcohol-based nasal sanitizer in the pre-operative and prolonged post-operative setting decreased infection rates by 41.3% in our elective total joint arthroplasty setting. Conclusions: When used pre- and post-operatively, alcohol-based nasal decolonization of bacteria in patients undergoing total joint arthroplasty led to a substantial decrease in SSIs.

SHEA/IDSA/APIC Practice Recommendation: Strategies to prevent methicillin-resistant Staphylococcus aureus transmission and infection in acute-care hospitals: 2022 Update

Previously published guidelines have provided comprehensive recommendations for detecting and preventing healthcare-associated infections (HAIs). The intent of this document is to highlight practical recommendations in a concise format designed to assist acute-care hospitals in implementing and prioritizing efforts to prevent methicillin-resistant Staphylococcus aureus (MRSA) transmission and infection. This document updates the "Strategies to Prevent Methicillin-Resistant Staphylococcus aureus Transmission and Infection in Acute Care Hospitals" published in 2014.1 This expert guidance document is sponsored by the Society for Healthcare Epidemiology of America (SHEA). It is the product of a collaborative effort led by SHEA, the Infectious Diseases Society of America (IDSA), the Association for Professionals in Infection Control and Epidemiology (APIC), the American Hospital Association (AHA), and The Joint Commission, with major contributions from representatives of a number of organizations and societies with content expertise.

Strategies to prevent surgical site infections in acute-care hospitals: 2022 Update

The intent of this document is to highlight practical recommendations in a concise format designed to assist acute-care hospitals in implementing and prioritizing their surgical-site infection (SSI) prevention efforts. This document updates the Strategies to Prevent Surgical Site Infections in Acute Care Hospitals published in 2014. This expert guidance document is sponsored by the Society for Healthcare Epidemiology of America (SHEA). It is the product of a collaborative effort led by SHEA, the Infectious Diseases Society of America (IDSA), the Association for Professionals in Infection Control and Epidemiology (APIC), the American Hospital Association (AHA), and The Joint Commission, with major contributions from representatives of a number of organizations and societies with content expertise.

Evaluation of ebselen in resolving a methicillin-resistant Staphylococcus aureus infection of pressure ulcers in obese and diabetic mice

Pressure ulcers (PUs) are a source of morbidity in individuals with restricted mobility including individuals that are obese or diabetic. Infection of PUs with pathogens, including methicillin-resistant Staphylococcus aureus (MRSA), impairs ulcers from healing. The present study evaluated ebselen as a topical antibacterial to treat MRSA-infected PUs. Against two different S. aureus strains, including MRSA USA300, resistance to ebselen did not emerge after 14 consecutive passages. Resistance to mupirocin emerged after only five passages. Additionally, ebselen was found to exert a modest postantibiotic effect of five hours against two MRSA strains. Ebselen was subsequently evaluated in MRSA-infected PUs in two models using obese and diabetic mice. In obese mice, topical ebselen (89.2% reduction) and oral linezolid (84.5% reduction) similarly reduced the burden of MRSA in infected PUs. However, in diabetic mice, topical ebselen (45.8% reduction in MRSA burden) was less effective. Histopathological evaluation of ulcers in diabetic mice determined that ebselen treatment resulted in fewer bacterial colonies deep within the dermis and that the treatment exhibited evidence of epithelial regeneration. Topical mupirocin was superior to ebselen in reducing MRSA burden in infected PUs both in obese (98.7% reduction) and diabetic (99.3% reduction) mice. Ebselen’s antibacterial activity was negatively impacted as the bacterial inoculum was increased from 10⁵ CFU/mL to 10⁷ CFU/mL. These results suggest that a higher dose of ebselen, or a longer course of treatment, may be needed to achieve a similar effect as mupirocin in topically treating MRSA-infected pressure ulcers.

Povidone Iodine: Properties, Mechanisms of Action, and Role in Infection Control and Staphylococcus aureus Decolonization

Nasal decolonization is an integral part of the strategies used to control and prevent the spread of methicillin-resistant Staphylococcus aureus (MRSA) infections. The two most commonly used agents for decolonization are intranasal mupirocin 2% ointment and chlorhexidine wash, but the increasing emergence of resistance and treatment failure has underscored the need for alternative therapies. This article discusses povidone iodine (PVP-I) as an alternative decolonization agent and is based on literature reviewed during an expert’s workshop on resistance and MRSA decolonization.

Nasal decolonization is an integral part of the strategies used to control and prevent the spread of methicillin-resistant Staphylococcus aureus (MRSA) infections. The two most commonly used agents for decolonization are intranasal mupirocin 2% ointment and chlorhexidine wash, but the increasing emergence of resistance and treatment failure has underscored the need for alternative therapies. This article discusses povidone iodine (PVP-I) as an alternative decolonization agent and is based on literature reviewed during an expert’s workshop on resistance and MRSA decolonization. Compared to chlorhexidine and mupirocin, respectively, PVP-I 10 and 7.5% solutions demonstrated rapid and superior bactericidal activity against MRSA in in vitro and ex vivo studies. Notably, PVP-I 10 and 5% solutions were also active against both chlorhexidine-resistant and mupirocin-resistant strains, respectively. Unlike chlorhexidine and mupirocin, available reports have not observed a link between PVP-I and the induction of bacterial resistance or cross-resistance to antiseptics and antibiotics. These preclinical findings also translate into clinical decolonization, where intranasal PVP-I significantly improved the efficacy of chlorhexidine wash and was as effective as mupirocin in reducing surgical site infection in orthopedic surgery. Overall, these qualities of PVP-I make it a useful alternative decolonizing agent for the prevention of S. aureus infections, but additional experimental and clinical data are required to further evaluate the use of PVP-I in this setting.

A two-part phase 1 study to establish and compare the safety and local tolerability of two nasal formulations of XF-73 for decolonisation of Staphylococcus aureus: A previously investigated 0.5mg/g viscosified gel formulation versus a modified formulation

OBJECTIVES

Successful decolonisation of nasal Staphylococcus aureus (SA) carriage by mupirocin is limited by increasing drug resistance. This randomised, open-label, phase 1 study compared the safety and local tolerability of two nasal formulations of XF-73, a novel porphyrinic antibacterial with rapid intrinsic activity against SA.

METHODS

The study was performed in 60 healthy adults. In Part 1, eight non-SA carriers were randomised to groups of four subjects each and were treated with XF-73 concentrations of 0.5mg/g 2% gel or 2.0mg/g 2% gel. In Part 2, 52 persistent SA carriers were randomised to groups of 13 subjects each and were treated with XF-73 concentrations of 0.5mg/g 2% gel, 2.0mg/g 2% gel, 0.5mg/g 4% gel or 4% viscosified placebo gel. Plasma pharmacokinetic and pharmacodynamic studies were performed. Antistaphylococcal activity was assessed as the presence/absence of SA and by quantification of colonisation using a semiquantitative scale (SA score).

RESULTS

56 subjects (8/8 from Part 1 and 48/52 from Part 2) completed the study, with 47/60 comprising the pharmacokinetic population and 48/60 the pharmacodynamic population. There was no measurable systemic absorption of XF-73. XF-73 treatment was associated with rapid reduction in SA score in all subjects. The most common treatment-emergent adverse events (TEAEs) were rhinorrhoea and nasal dryness (15.5% each in Parts 1 and 2). TEAEs were mild and resolved spontaneously.

CONCLUSION

XF-73 was well tolerated with minimal side effects at doses of 0.5mg/g 2% gel and 2.0mg/g 2% gel. These findings support further development of XF-73.

Antimicrobial resistance in methicillin-resistant Staphylococcus aureus to newer antimicrobial agents

Infections caused by methicillin-resistant Staphylococcus aureus (MRSA) result in significant morbidity and mortality for patients in both community and health care settings. This is primarily due to the difficulty in treating MRSA, which is often resistant to multiple classes of antibiotics. Understanding the mechanisms of antimicrobial resistance (AMR) in MRSA provides insight into the optimal use of antimicrobial agents in clinical practice and also underpins critical aspects of antimicrobial stewardship programs. In this review we delineate the mechanisms, prevalence, and clinical importance of resistance to antibiotics licensed in the past 20 years that target MRSA, as well as new drugs in the pipeline which are likely to be licensed soon. Current gaps in scientific knowledge about MRSA resistance mechanisms are discussed, and topics in the epidemiology of AMR in S. aureus that require further investigation are highlighted.

Antimicrobial resistance in nephrology

The prevalence of antimicrobial resistance among many common bacterial pathogens is increasing. The emergence and global dissemination of these antibiotic-resistant bacteria (ARB) is fuelled by antibiotic selection pressure, inter-organism transmission of resistance determinants, suboptimal infection prevention practices and increasing ease and frequency of international travel, among other factors. Patients with chronic kidney disease, particularly those with end-stage renal disease who require dialysis and/or kidney transplantation, have some of the highest rates of colonization and infection with ARB worldwide. These ARB include methicillin-resistant Staphylococcus aureus, vancomycin-resistant Enterococcus spp. and several multidrug-resistant Gram-negative organisms. Antimicrobial resistance limits treatment options and increases the risk of infection-related morbidity and mortality. Several new antibiotic agents with activity against some of the most common ARB have been developed, but resistance to these agents is already emerging and highlights the dire need for new treatment options as well as consistent implementation and improvement of basic infection prevention practices. Clinicians involved in the care of patients with renal disease must be familiar with the local epidemiology of ARB, remain vigilant for the emergence of novel resistance patterns and adhere strictly to practices proven to prevent transmission of ARB and other pathogens.

Nasal Decolonisation of MRSA

The recent demonstration for the first time of urinary monic acid A as a clinical urinary biomarker of exposure to intra-nasal mupirocin during medication for methicillin-resistant Staphylococcus aureus (MRSA) offers a way of verifying adherence to the regimen. However, absence of the biomarker in some patients needs explanation, to ensure that efficient decolonisation has not been compromised by confounding circumstances, and that additional resistance to mupirocin has not unwittingly been encouraged.

Decolonization of Staphylococcus aureus in Healthcare: A Dermatology Perspective

The bacterium Staphylococcus aureus is responsible for significant morbidity, mortality, and financial burden in healthcare. It easily colonizes susceptible patients and can cause recurrent infections, especially in populations at risk. In addition to treating sequelae of infections, there is a growing body of literature aimed at decolonizing susceptible patients in order to prevent infection and also to prevent spread. Such strategies are widely employed in surgical, intensive care, and hospitalist fields. Staphylococcus aureus involvement has been implicated in the pathogenesis and persistence of many dermatologic diseases that are treated in the outpatient setting. This review serves to summarize current evidence for the management of Staphylococcus aureus colonized patients, as well as the evidence available for decolonization. We further characterize the role that colonization may play in atopic dermatitis, recurrent infections, hand eczema, cutaneous T-cell lymphoma, and also in surgical infections after Mohs surgery.

Antimicrobial Resistance to Agents Used for Staphylococcus aureus Decolonization: Is There a Reason for Concern?

PURPOSE OF REVIEW

Chlorhexidine gluconate (CHG) and mupirocin are increasingly used for Staphylococcus aureus decolonization to prevent healthcare-associated infections; however, increased use of these agents has led to concerns for growing resistance and reduced efficacy. In this review, we describe current understanding of reduced susceptibility to CHG and mupirocin in S. aureus and their potential clinical implications.

RECENT FINDINGS

While emergence of S. aureus tolerant or resistant to topical antimicrobial agents used for decolonization is well described, the clinical impact of reduced susceptibility is not clear. Important challenges are that standardized methods of resistance testing and interpretation are not established, and the risk for selection for co- or cross-resistance using universal, as opposed to targeted decolonization, is unclear. Evidence continues to support S. aureus decolonization in certain patient groups, although further studies are needed to determine the long-term impact of CHG and mupirocin resistance on efficacy. Strategies to mitigate further development of reduced susceptibility and the consequences of selection pressures through universal decolonization on resistance will benefit from further investigation.

Antibacterial Prophylaxis for Surgical Site Infection in the Elderly: Practical Application

Surgical site infections are among the most common healthcare-associated infections and are linked with increased length of hospitalization, re-admission, mortality and significant financial burden. Risk factors for the occurrence of surgical site infections include variables related to the surgical procedure as well as host factors. Increasing age is associated with the occurrence of surgical site infections. The aim of this review is to give an update on the antibiotic prophylaxis for surgical site infection in elderly people. We focused on specific issues and practical applications, such as the importance of targeting the antimicrobial agent to the susceptibility pattern of colonizing flora in selected cases and the need for dosage modifications.

Topical antibiotics for preventing surgical site infection in wounds healing by primary intention

BACKGROUND

Surgical site infections (SSI) can delay wound healing, impair cosmetic outcome and increase healthcare costs. Topical antibiotics are sometimes used to reduce microbial contaminant exposure following surgical procedures, with the aim of reducing SSIs.

OBJECTIVES

The primary objective of this review was to determine whether the application of topical antibiotics to surgical wounds that are healing by primary intention reduces the incidence of SSI and whether it increases the incidence of adverse outcomes (allergic contact dermatitis, infections with patterns of antibiotic resistance and anaphylaxis).

SEARCH METHODS

In May 2015 we searched: the Cochrane Wounds Specialised Register; the Cochrane Central Register of Controlled Trials (CENTRAL; the Cochrane Library); Ovid MEDLINE; Ovid MEDLINE (In-Process & Other Non-Indexed Citations); Ovid Embase and EBSCO CINAHL. We also searched clinical trial registries for ongoing studies, and bibliographies of relevant publications to identify further eligible trials. There was no restriction of language, date of study or setting. The search was repeated in May 2016 to ensure currency of included studies.

SELECTION CRITERIA

All randomized controlled trials (RCTs) and quasi-randomised trials that assessed the effects of topical antibiotics (any formulation, including impregnated dressings) in people with surgical wounds healing by primary intention were eligible for inclusion.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected studies and independently extracted data. Two authors then assessed the studies for risk of bias. Risk ratios were calculated for dichotomous variables, and when a sufficient number of comparable trials were available, trials were pooled in a meta-analysis.

MAIN RESULTS

A total of 10 RCTs and four quasi-randomised trials with 6466 participants met the inclusion criteria. Six studies involved minor procedures conducted in an outpatient or emergency department setting; eight studies involved major surgery conducted in theatre. Nine different topical antibiotics were included. We included two three-arm trials, two four-arm trials and 10 two-arm trials. The control groups comprised; an alternative topical antibiotic (two studies), topical antiseptic (six studies) and no topical antibiotic (10 studies), which comprised inert ointment (five studies) no treatment (four studies) and one study with one arm of each.The risk of bias of the 14 studies varied. Seven studies were at high risk of bias, five at unclear risk of bias and two at low risk of bias. Most risk of bias concerned risk of selection bias.Twelve of the studies (6259 participants) reported infection rates, although we could not extract the data for this outcome from one study. Four studies (3334 participants) measured allergic contact dermatitis as an outcome. Four studies measured positive wound swabs for patterns of antimicrobial resistance, for which there were no outcomes reported. No episodes of anaphylaxis were reported. Topical antibiotic versus no topical antibioticWe pooled the results of eight trials (5427 participants) for the outcome of SSI. Topical antibiotics probably reduce the risk of SSI in people with surgical wounds healing by primary intention compared with no topical antibiotic (RR 0.61, 95% CI 0.42 to 0.87; moderate-quality evidence downgraded once for risk of bias). This equates to 20 fewer SSIs per 1000 patients treated with topical antibiotics (95% CI 7 to 29) and a number needed to treat for one additional beneficial outcome (NNTB) (i.e. prevention of one SSI) of 50.We pooled the results of three trials (3012 participants) for the outcome of allergic contact dermatitis, however this comparison was underpowered, and it is unclear whether topical antibiotics affect the risk of allergic contact dermatitis (RR 3.94, 95% CI 0.46 to 34.00; very low-quality evidence, downgraded twice for risk of bias, once for imprecision). Topical antibiotic versus antiseptic We pooled the results of five trials (1299 participants) for the outcome of SSI. Topical antibiotics probably reduce the risk of SSI in people with surgical wounds healing by primary intention compared with using topical antiseptics (RR 0.49, 95% CI 0.30 to 0.80; moderate-quality evidence downgraded once for risk of bias). This equates to 43 fewer SSIs per 1000 patients treated with topical antibiotics instead of antiseptics (95% CI 17 to 59) and an NNTB of 24.We pooled the results of two trials (541 participants) for the outcome of allergic contact dermatitis; there was no clear difference in the risk of dermatitis between topical antibiotics and antiseptics, however this comparison was underpowered and a difference cannot be ruled out (RR 0.97, 95% CI 0.52 to 1.82; very low-quality evidence, downgraded twice for risk of bias and once for imprecision). Topical antibiotic versus topical antibioticOne study (99 participants) compared mupirocin ointment with a combination ointment of neomycin/polymyxin B/bacitracin zinc for the outcome of SSI. There was no clear difference in the risk of SSI, however this comparison was underpowered (very low-quality evidence downgraded twice for risk of bias, once for imprecision).A four-arm trial involved two antibiotic arms (neomycin sulfate/bacitracin zinc/polymyxin B sulphate combination ointment versus bacitracin zinc, 219 participants). There was no clear difference in risk of SSI between the combination ointment and the bacitracin zinc ointment. The quality of evidence for this outcome was low, downgraded once for risk of bias, and once for imprecision.

AUTHORS' CONCLUSIONS

Topical antibiotics applied to surgical wounds healing by primary intention probably reduce the risk of SSI relative to no antibiotic, and relative to topical antiseptics (moderate quality evidence). We are unable to draw conclusions regarding the effects of topical antibiotics on adverse outcomes such as allergic contact dermatitis due to lack of statistical power (small sample sizes). We are also unable to draw conclusions regarding the impact of increasing topical antibiotic use on antibiotic resistance. The relative effects of different topical antibiotics are unclear.

Chlorhexidine and Mupirocin Susceptibility of Methicillin-Resistant Staphylococcus aureus Isolates in the REDUCE-MRSA Trial

Whether targeted or universal decolonization strategies for the control of methicillin-resistant Staphylococcus aureus (MRSA) select for resistance to decolonizing agents is unresolved. The REDUCE-MRSA trial (ClinicalTrials registration no. NCT00980980) provided an opportunity to investigate this question. REDUCE-MRSA was a 3-arm, cluster-randomized trial of either screening and isolation without decolonization, targeted decolonization with chlorhexidine and mupirocin, or universal decolonization without screening to prevent MRSA infection in intensive-care unit (ICU) patients. Isolates from the baseline and intervention periods were collected and tested for susceptibility to chlorhexidine gluconate (CHG) by microtiter dilution; mupirocin susceptibility was tested by Etest. The presence of the qacA or qacB gene was determined by PCR and DNA sequence analysis. A total of 3,173 isolates were analyzed; 2 were nonsusceptible to CHG (MICs, 8 μg/ml), and 5/814 (0.6%) carried qacA or qacB At baseline, 7.1% of MRSA isolates expressed low-level mupirocin resistance, and 7.5% expressed high-level mupirocin resistance. In a mixed-effects generalized logistic regression model, the odds of mupirocin resistance among clinical MRSA isolates or MRSA isolates acquired in an ICU in intervention versus baseline periods did not differ across arms, although estimates were imprecise due to small numbers. Reduced susceptibility to chlorhexidine and carriage of qacA or qacB were rare among MRSA isolates in the REDUCE-MRSA trial. The odds of mupirocin resistance were no different in the intervention versus baseline periods across arms, but the confidence limits were broad, and the results should be interpreted with caution.

Prevention of Recurrent Staphylococcal Skin Infections

Staphylococcus aureus infections pose a significant health burden. The emergence of community-associated methicillin-resistant S aureus has resulted in an epidemic of skin and soft tissue infections (SSTI), and many patients experience recurrent SSTI. As S aureus colonization is associated with subsequent infection, decolonization is recommended for patients with recurrent SSTI or in settings of ongoing transmission. S aureus infections often cluster within households, and asymptomatic carriers serve as reservoirs for transmission; therefore, a household approach to decolonization is more effective than measures performed by individuals alone. Novel strategies for the prevention of recurrent SSTI are needed.

Prevalence of qacA/B Genes and Mupirocin Resistance Among Methicillin-Resistant Staphylococcus aureus (MRSA) Isolates in the Setting of Chlorhexidine Bathing Without Mupirocin

OBJECTIVE

We aimed to determine the frequency of qacA/B chlorhexidine tolerance genes and high-level mupirocin resistance among MRSA isolates before and after the introduction of a chlorhexidine (CHG) daily bathing intervention in a surgical intensive care unit (SICU).

DESIGN

Retrospective cohort study (2005-2012) SETTING: A large tertiary-care center

PATIENTS

Patients admitted to SICU who had MRSA surveillance cultures of the anterior nares

METHODS

A random sample of banked MRSA anterior nares isolates recovered during (2005) and after (2006-2012) implementation of a daily CHG bathing protocol was examined for qacA/B genes and high-level mupirocin resistance. Staphylococcal cassette chromosome mec (SCCmec) typing was also performed.

RESULTS

Of the 504 randomly selected isolates (63 per year), 36 (7.1%) were qacA/B positive (+) and 35 (6.9%) were mupirocin resistant. Of these, 184 (36.5%) isolates were SCCmec type IV. There was a significant trend for increasing qacA/B (P=.02; highest prevalence, 16.9% in 2009 and 2010) and SCCmec type IV (P<.001; highest prevalence, 52.4% in 2012) during the study period. qacA/B(+) MRSA isolates were more likely to be mupirocin resistant (9 of 36 [25%] qacA/B(+) vs 26 of 468 [5.6%] qacA/B(-); P=.003).

CONCLUSIONS

A long-term, daily CHG bathing protocol was associated with a change in the frequency of qacA/B genes in MRSA isolates recovered from the anterior nares over an 8-year period. This change in the frequency of qacA/B genes is most likely due to patients in those years being exposed in prior admissions. Future studies need to further evaluate the implications of universal CHG daily bathing on MRSA qacA/B genes among hospitalized patients.

Active Surveillance Cultures and Decolonization to Reduce Staphylococcus aureus Infections in the Neonatal Intensive Care Unit

BACKGROUND

Staphylococcus aureus is a common cause of healthcare-associated infections in neonates.

OBJECTIVE

To examine the impact of methicillin-susceptible S. aureus (MSSA) decolonization on the incidence of MSSA infection and to measure the prevalence of mupirocin resistance.

METHODS

We retrospectively identified neonates admitted to a tertiary care neonatal intensive care unit (NICU) from April 1, 2011, through September 30, 2014. We compared rates of MSSA-positive cultures and infections before and after implementation of an active surveillance culture and decolonization intervention for MSSA-colonized neonates. We used 2 measurements to identify the primary outcome, NICU-attributable MSSA: (1) any culture sent during routine clinical care that grew MSSA and (2) any culture that grew MSSA and met criteria of the National Healthcare Safety Network's healthcare-associated infection surveillance definitions. S. aureus isolates were tested for mupirocin susceptibility. We estimated incidence rate ratios using interrupted time-series models.

RESULTS

Before and after the intervention, 1,523 neonates (29,220 patient-days) and 1,195 neonates (22,045 patient-days) were admitted to the NICU, respectively. There was an immediate reduction in the mean quarterly incidence rate of NICU-attributable MSSA-positive clinical cultures of 64% (incidence rate ratio, 0.36 [95% CI, 0.19-0.70]) after implementation of the intervention, and MSSA-positive culture rates continued to decrease by 21% per quarter (incidence rate ratio, 0.79 [95% CI, 0.74-0.84]). MSSA infections also decreased by 73% immediately following the intervention implementation (incidence rate ratio, 0.27 [95% CI, 0.10-0.79]). No mupirocin resistance was detected.

CONCLUSION

Active surveillance cultures and decolonization may be effective in decreasing S. aureus infections in NICUs.

In Vitro Activity of Retapamulin and Antimicrobial Susceptibility Patterns in a Longitudinal Collection of Methicillin-Resistant Staphylococcus aureus Isolates from a Veterans Affairs Medical Center

Mupirocin is a topical antimicrobial used to decolonize patients who carry methicillin-resistant Staphylococcus aureus (MRSA), and the topical agent retapamulin may be a potential alternative therapy. The goal of this study was to determine the in vitro activity of retapamulin as well as a panel of 15 antimicrobial agents, including mupirocin, for 403 MRSA isolates collected longitudinally from a naive population at the Veterans Affairs Puget Sound Health Care System. The MICs for retapamulin had a unimodal distribution, ranging from 0.008 to 0.5 μg/ml. One isolate had an MIC of >16 μg/ml, was also resistant to clindamycin and erythromycin, and was recovered from the nares of a patient undergoing hemodialysis. Twenty-four isolates (6%) and 11 isolates (3%) demonstrated low-level resistance (MICs of 8 to 64 μg/ml) and high-level resistance (MICs of ≥ 512 μg/ml), respectively, to mupirocin. Isolates were recovered from 10 patients both before and after mupirocin therapy. Of those, isolates from 2 patients demonstrated MIC changes postmupirocin therapy; in both cases, however, strain typing demonstrated that the pre- and postmupirocin strains were different. A total of 386 isolates (96%) had vancomycin MICs of ≤ 1.0 μg/ml; 340 isolates (84%) were resistant to levofloxacin, 18 isolates (4.5%) were resistant to trimethoprim-sulfamethoxazole, and 135 isolates (33%) had elevated MICs of 4 μg/ml for linezolid. The baseline levels of resistance were low for mupirocin (9%) and even lower for retapamulin (0.25%) Although the use of mupirocin is currently the standard therapy for decolonization practices, the activity of retapamulin warrants its consideration as an alternative therapy in MRSA decolonization regimens.

Clinical and Molecular Features of Decreased Chlorhexidine Susceptibility among Nosocomial Staphylococcus aureus Isolates at Texas Children's Hospital

One of the strategies utilized to decrease infections in the hospital setting relies on topical antimicrobials and antiseptics. While their use is beneficial, concerns arise over the potential to develop resistance or tolerance to these agents. We examined nosocomial Staphylococcus aureus isolates from 2007 to 2013 for the presence of genes associated with tolerance to chlorhexidine. Isolates and patients were identified from an S. aureus surveillance study at Texas Children's Hospital. Nosocomial S. aureus isolates (those causing infection at ≥72 h of hospitalization) were identified and underwent PCR for the qacA or qacB (qacA/B) and smr genes associated with elevated minimum bactericidal concentrations of chlorhexidine. Molecular typing with pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST), and agr typing and a review of the medical record were performed. Two hundred forty-seven nosocomial S. aureus infections were identified. Overall, 111 isolates carried one or both genes (44.9%); 33.1% were positive for smr, 22.7% were positive for qacA/B, and 10.9% of the isolates possessed both genes. The smr-positive isolates were more often resistant to methicillin, ciprofloxacin, and/or clindamycin. The isolates positive for qacA/B were more often associated with indwelling central venous catheters and a vancomycin MIC of ≥2 μg/ml. Isolates carrying either smr or qacA/B were associated with a diagnosis of bacteremia. The smr-positive isolates more often belonged to sequence type 8 (ST8) than the isolates that were positive for qacA/B. Mupirocin resistance was detected in 2.8% of the isolates. Antiseptic-tolerant S. aureus strains are common in our children's hospital and are associated with decreased susceptibility to other systemic antimicrobials and with bloodstream infections. Further work is needed to understand the implications that these organisms have on the hospital environment and antiseptic use in the future.

Antibacterial Evaluation of Synthetic Thiazole Compounds In Vitro and In Vivo in a Methicillin-Resistant Staphylococcus aureus (MRSA) Skin Infection Mouse Model

The emergence of community-associated methicillin-resistant Staphylococcus aureus (MRSA), including strains resistant to current antibiotics, has contributed to an increase in the number of skin infections reported in humans in recent years. New therapeutic options are needed to counter this public health challenge. The aim of the present study was to examine the potential of thiazole compounds synthesized by our research group to be used topically to treat MRSA skin and wound infections. The broth microdilution method confirmed that the lead thiazole compound and four analogues are capable of inhibiting MRSA growth at concentrations as low as 1.3 μg/mL. Additionally, three compounds exhibited a synergistic relationship when combined with the topical antibiotic mupirocin against MRSA in vitro via the checkerboard assay. Thus the thiazole compounds have potential to be used alone or in combination with mupirocin against MRSA. When tested against human keratinocytes, four derivatives of the lead compound demonstrated an improved toxicity profile (were found to be non-toxic up to a concentration of 20 μg/mL). Utilizing a murine skin infection model, we confirmed that the lead compound and three analogues exhibited potent antimicrobial activity in vivo, with similar capability as the antibiotic mupirocin, as they reduced the burden of MRSA present in skin wounds by more than 90%. Taken altogether, the present study provides important evidence that these thiazole compounds warrant further investigation for development as novel topical antimicrobials to treat MRSA skin infections.

Methicillin-resistant Staphylococcus aureus transmission and infections in a neonatal intensive care unit despite active surveillance cultures and decolonization: challenges for infection prevention

OBJECTIVE

To characterize the epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) transmission and infections in a level IIIC neonatal intensive care unit (NICU) and identify barriers to MRSA control.

SETTING AND DESIGN

Retrospective cohort study in a university-affiliated NICU with an MRSA control program including weekly nares cultures of all neonates and admission nares cultures for neonates transferred from other hospitals or admitted from home.

METHODS

Medical records were reviewed to identify neonates with NICU-acquired MRSA colonization or infection between April 2007 and December 2011. Compliance with hand hygiene and an MRSA decolonization protocol were monitored. Relatedness of MRSA strains were assessed using pulsed-field gel electrophoresis (PFGE).

RESULTS

Of 3,536 neonates, 74 (2.0%) had a culture grow MRSA, including 62 neonates with NICU-acquired MRSA. Nineteen of 74 neonates (26%) had an MRSA infection, including 8 who became infected before they were identified as MRSA colonized, and 11 of 66 colonized neonates (17%) developed a subsequent infection. Of the 37 neonates that underwent decolonization, 6 (16%) developed a subsequent infection, and 7 of 14 (50%) that remained in the NICU for 21 days or more became recolonized with MRSA. Using PFGE, there were 14 different strain types identified, with USA300 being the most common (31%).

CONCLUSIONS

Current strategies to prevent infections-including active identification and decolonization of MRSA-colonized neonates-are inadequate because infants develop infections before being identified as colonized or after attempted decolonization. Future prevention efforts would benefit from improving detection of MRSA colonization, optimizing decolonization regimens, and identifying and interrupting reservoirs of transmission.

Decolonization to prevent Staphylococcus aureus transmission and infections in the neonatal intensive care unit

Staphylococcus aureus (S. aureus) continues to be a leading cause of outbreaks and health-care-associated infections in neonatal intensive care units. In the first few months of life, many neonates acquire S. aureus as part of their delicate and evolving microbiota. Neonates that asymptomatically acquire S. aureus colonization are at increased risk of developing a subsequent S. aureus infection. This review discusses the epidemiology and prevention of S. aureus disease in neonates and how decolonization to eradicate S. aureus may decrease S. aureus transmission and infections in the neonatal intensive care unit.

Strategies to prevent surgical site infections in acute care hospitals: 2014 update

Previously published guidelines are available that provide comprehensive recommendations for detecting and preventing healthcare-associated infections (HAIs). The intent of this document is to highlight practical recommendations in a concise format designed to assist acute care hospitals in implementing and prioritizing their surgical site infection (SSI) prevention efforts. This document updates “Strategies to Prevent Surgical Site Infections in Acute Care Hospitals,”1 published in 2008. This expert guidance document is sponsored by the Society for Healthcare Epidemiology of America (SHEA) and is the product of a collaborative effort led by SHEA, the Infectious Diseases Society of America (IDSA), the American Hospital Association (AHA), the Association for Professionals in Infection Control and Epidemiology (APIC), and The Joint Commission, with major contributions from representatives of a number of organizations and societies with content expertise. The list of endorsing and supporting organizations is presented in the introduction to the 2014 updates.2

Survey of policy for MRSA screening in English cataract surgical units and changes to practice after updated National guidelines

Background

National guidelines on MRSA (methicillin-resistant Staphylococcus aureus) screening policy in England have changed on a number of occasions, but there is limited data on its influence at a local level. The aim of this study was to determine if changes in National policy influenced preoperative screening of cataract patients for MRSA.

Methods

A structured telephone survey was conducted on all 133 ophthalmology units in England in 2004 and again in 2007 for the initial responders, after a change in national policy.

Results

A total of 74 units (56%) responded in 2004 and 71 units (96% of initial respondents) in 2007. In 2004, 57% of units screened for MRSA. They screened groups at high risk of carriage, including patients with previous MRSA (93%) and patients from Nursing homes (21%). Swab sites included the nose (100%), eyes (31%) and perineum (62%). In 2007, there was no significant change in the number of units that screened for MRSA (57% vs 66%; p = 0.118; McNemar test). However, more units screened for MRSA in patients from nursing/residential homes (21% vs 51%; p = 0.004, McNemar test), and in patients who had recent admission to hospital (12% vs 36%; p = 0.003). In the second survey, 3 units (6%) now screened patients who were close relatives of MRSA carriers.

Conclusion

This survey has highlighted inconsistences in MRSA screening practice of day-case cataract surgery patients across England after 2 major national policy changes. A change in DoH policy only led to more units screening patients for MRSA from high risk groups.

Decolonization with Mupirocin and Subsequent Risk of Methicillin-Resistant Staphylococcus aureus Carriage in Veterans Affairs Hospitals

Introduction

Hospital-acquired methicillin-resistant Staphylococcus aureus (MRSA) infections remain one of the leading causes of preventable patient mortality in the US. Eradication of MRSA through decolonization could prevent both MRSA infections and transmission; however, there is currently no consensus within the infectious disease community on the proper role of decolonization in the prevention of infections. The purpose of this study was to assess the impact of decolonization with mupirocin on subsequent MRSA carriage.

Methods

Patients included in this study were those with an inpatient admission to a Department of Veterans Affairs (VA) hospital between January 1, 2008 and December 31, 2009 who had a positive MRSA screen on admission and a subsequent re-admission during the same time period. Exposure to mupirocin on the initial hospital admission was measured using Barcode Medication Administration data and MRSA carriage was measured using microbiology text reports and lab data containing results from surveillance swabs collected from the nares. Chi-square tests were used to test for differences in re-admission MRSA carriage rates between mupirocin-receiving and non-mupirocin-receiving patients.

Results

Of the 25,282 MRSA-positive patients with a subsequent re-admission included in the present study cohort, 1,183 (4.7%) received mupirocin during their initial hospitalization. Among the patients in the present study cohort who were re-admitted within 30 days, those who received mupirocin were less likely to test positive for MRSA carriage than those who did not receive mupirocin (27.2% vs. 55.1%, P < 0.001). The proportion of those who tested positive for MRSA during re-admissions that occurred 30–60 days, 60–120 days, and >120 days were 33.9, 37.3, and 41.0%, respectively, among mupirocin patients and 52.7%, 53.0%, and 51.9%, respectively, for patients who did not receive mupirocin (P < 0.001 at each time point).

Conclusion

Patients decolonized with mupirocin in VA hospitals were less likely to be colonized with MRSA on re-admission as long as 4 months after decolonization.

Mupirocin and chlorhexidine resistance in Staphylococcus aureus in patients with community-onset skin and soft tissue infections

Decolonization measures, including mupirocin and chlorhexidine, are often prescribed to prevent Staphylococcus aureus skin and soft tissue infections (SSTI). The objective of this study was to determine the prevalence of high-level mupirocin and chlorhexidine resistance in S. aureus strains recovered from patients with SSTI before and after mupirocin and chlorhexidine administration and to determine whether carriage of a mupirocin- or chlorhexidine-resistant strain at baseline precluded S. aureus eradication. We recruited 1,089 patients with community-onset SSTI with or without S. aureus colonization. In addition to routine care, 483 patients were enrolled in a decolonization trial: 408 received intranasal mupirocin (with or without antimicrobial baths), and 258 performed chlorhexidine body washes. Patients were followed for up to 12 months with repeat colonization cultures. All S. aureus isolates were tested for high-level mupirocin and chlorhexidine resistance. At baseline, 23/1,089 (2.1%) patients carried a mupirocin-resistant S. aureus strain and 10/1,089 (0.9%) patients carried chlorhexidine-resistant S. aureus. Of 4 patients prescribed mupirocin, who carried a mupirocin-resistant S. aureus strain at baseline, 100% remained colonized at 1 month compared to 44% of the 324 patients without mupirocin resistance at baseline (P = 0.041). Of 2 patients prescribed chlorhexidine, who carried a chlorhexidine-resistant S. aureus strain at baseline, 50% remained colonized at 1 month compared to 48% of the 209 patients without chlorhexidine resistance at baseline (P = 1.0). The overall prevalence of mupirocin and chlorhexidine resistance is low in S. aureus isolates recovered from outpatients, but eradication efforts were less successful in patients carrying a mupirocin-resistant S. aureus strain at baseline.

Antibiotic overuse and resistance in dermatology

Antibiotics have a significant role in dermatology, treating a wide range of diseases, including acne, rosacea, inflammatory skin conditions and skin structure infections, such as cellulitis, folliculitis, carbuncles, and furuncles. Because of their consistent use, utility, and availability, antibiotics are susceptible to overuse within the medical practice, and, specific to this discussion, in the dermatologic setting. The issue of continuously increasing risk of antibiotic resistance remains an important concern to the dermatologist. The scope of this review will be to provide an overview of the common antibiotics used in the dermatologic setting with an emphasis on identifying areas of overuse, reported bacterial resistance, and discussion of clinical management aimed at decreasing antibiotic resistance.

Emergence of high-level mupirocin resistance in coagulase-negative staphylococci associated with increased short-term mupirocin use

In our hospital, mupirocin has increasingly been used for peri-operative decolonization of Staphylococcus aureus. The target for mupirocin is isoleucyl tRNA synthetase (ileS). High-level resistance to mupirocin is conferred by acquisition of plasmids expressing a distinct ileS gene (ileS2). Here we evaluated the longitudinal trends in high-level mupirocin resistance in coagulase-negative staphylococci (CoNS) and linked this to the presence of ileS2 genes and mupirocin use. We assessed mupirocin resistance in CoNS bloodstream isolates from 2006 to 2011 tested by Phoenix automated testing (PAT). We evaluated the reliability of PAT results using Etest. PAT species determination was confirmed by MALDI-TOF (matrix-assisted laser desorption ionization-time of flight) mass spectrometry. We investigated the presence of ileS2 in the first 100 consecutive CoNS bloodstream isolates of each year using RT-PCR. Mupirocin use increased from 3.6 kg/year in 2006 to 13.3 kg/year in 2010 and correlated with the increase in the percentage of CoNS isolates carrying ileS2 (8% in 2006 to 22% in 2011; Spearman's rho, 0.137; P = 0.01). The sensitivity and specificity of PAT for detecting high-level mupirocin resistance were 0.97 and 0.97, respectively. ileS2 was detected in 81 of 82 phenotypically highly mupirocin-resistant strains and associated with resistance to ciprofloxacin, erythromycin, and clindamycin. In conclusion, we found a rapid increase in high-level resistance to mupirocin and resistance to other antibiotics in CoNS associated with an increase in mupirocin use. The associated resistance to other antibiotics may result in a reduction of oral antibiotic options for prolonged treatment of prosthetic infections with CoNS.

Effectiveness of measures to eradicate Staphylococcus aureus carriage in patients with community-associated skin and soft-tissue infections: a randomized trial

BACKGROUND

Despite a paucity of evidence, decolonization measures are prescribed for outpatients with recurrent Staphylococcus aureus skin and soft-tissue infection (SSTI).

OBJECTIVE

Compare the effectiveness of 4 regimens for eradicating S. aureus carriage.

DESIGN

Open-label, randomized controlled trial. Colonization status and recurrent SSTI were ascertained at 1 and 4 months.

SETTING

Barnes-Jewish and St. Louis Children's Hospitals, St. Louis, Missouri, 2007-2009.

PARTICIPANTS

Three hundred patients with community-onset SSTI and S. aureus colonization in the nares, axilla, or inguinal folds.

INTERVENTIONS

Participants were randomized to receive no therapeutic intervention (control subjects) or one of three 5-day regimens: 2% mupirocin ointment applied to the nares twice daily, intranasal mupirocin plus daily 4% chlorhexidine body washes, or intranasal mupirocin plus daily dilute bleach water baths.

RESULTS

Among 244 participants with 1-month colonization data, modified intention-to-treat analysis revealed S. aureus eradication in 38% of participants in the education only (control) group, 56% of those in the mupirocin group (P = .03 vs controls), 55% of those in the mupirocin and chlorhexidine group (P = .05), and 63% off those in the mupirocin and bleach group (P = .006). Of 229 participants with 4-month colonization data, eradication rates were 48% in the control group, 56% in the mupirocin only group (P = .40 vs controls), 54% in the mupirocin and chlorhexidine group (P = .51), and 71% in the mupirocin and bleach group (P = .02). At 1 and 4 months, recurrent SSTIs were reported by 20% and 36% of participants, respectively.

CONCLUSIONS

An inexpensive regimen of dilute bleach baths, intranasal mupirocin, and hygiene education effectively eradicated S. aureus over a 4-month period. High rates of recurrent SSTI suggest that factors other than endogenous colonization are important determinants of infection. Trial registration. ClinicalTrials.gov identifier: NCT00513799.

A double-blind, randomized, controlled trial of topical polysporin triple compound versus topical mupirocin for the eradication of colonization with methicillin-resistant Staphylococcus aureus in a complex continuing care population

BACKGROUND

Intranasal mupirocin or Polysporin Triple (PT) ointment (polymyxin B, bacitracin, gramicidin), in combination with chlorhexidine body washes, have been used for eradicating methicillin-resistant Staphylococcus aureus (MRSA), but no comparative studies have been done.

METHODS

A double-blind, randomized, controlled clinical trial to compare the efficacy of mupirocin versus PT ointment in combination with chlorhexidine body washes in eradicating MRSA carriage was conducted. Asymptomatic MRSA carriers, medically stable and at least 18 years of age who were patients on medical wards, received twice daily application of either mupirocin or PT ointment to the anterior nares plus once daily 2% chlorhexidine body washes for seven days. Follow-up swabs from multiple sites using broth enrichment were conducted at 48 h, and one, two, four, eight and 12 weeks.

RESULTS

Of 103 patients eligible for analysis (54 mupirocin; 49 PT), no significant differences between the two groups with respect to baseline demographics, risk factors for MRSA or MRSA colonization sites were noted. At 48 h, 35 of 54 (65%) patients in the mupirocin group versus 15 of 49 (31%) in the PT group (P=0.001) were found to be MRSA negative at all sites. Significant differences were observed at one and two weeks but were not maintained at other intervals. In those with complete microbiological follow-up, MRSA eradication at all sites occurred in 12 of 39 (30.8%) mupirocin- and one of 36 (2.8%) PT-treated patients (P=0.001).

CONCLUSION

Both agents demonstrated poor efficacy and PT was significantly less efficacious than mupirocin at 12 weeks in eradicating MRSA from all sites.

Prevention and management of prosthetic joint infection in older adults

Total joint arthroplasty (TJA) is commonly performed on older adults. Prosthetic joint infection (PJI) is a serious complication of TJA that can significantly impact quality of life and physical function. In this review, we discuss the epidemiology and risk factors for PJIs among older adults. We also offer an overview of current diagnostic, treatment and management strategies for PJI. Given the serious nature of PJI, prevention efforts remain essential. Several approaches to infection prevention exist, including antimicrobial prophylaxis and decolonization. Although there are standardized recommendations for antimicrobial prophylaxis, the specific regimens must be individualized based on the patient's drug allergies, potential for drug interactions, renal function and bodyweight. The best approach to pre-operative screening and decolonization programmes remains unclear. Each of these issues is reviewed in detail with a focus on adverse effects and current debates regarding best practice. Given the increased numbers of TJAs performed, additional research on prevention and management is critical.

Investigation of the potential for mutational resistance to XF-73, retapamulin, mupirocin, fusidic acid, daptomycin, and vancomycin in methicillin-resistant Staphylococcus aureus isolates during a 55-passage study

XF-73 is a dicationic porphyrin drug with rapid Gram-positive antibacterial activity currently undergoing clinical trials for the nasal decolonization of Staphylococcus aureus, including methicillin-resistant Staphylococcus aureus (MRSA). In multistep (55-passage) resistance selection studies in the presence of subinhibitory concentrations of XF-73, retapamulin, mupirocin, fusidic acid, and vancomycin against four Network on Antimicrobial Resistance in Staphylococcus aureus MRSA strains, there was no >4-fold increase in the MIC for XF-73 after 55 passages. In contrast, there was an increase in the MICs for retapamulin (from 0.25 μg/ml to 4 to 8 μg/ml), for mupirocin (from 0.12 μg/ml to 16 to 512 μg/ml), for fusidic acid (from 0.12 μg/ml to 256 μg/ml), and for vancomycin (from 1 μg/ml to 8 μg/ml in two of the four strains tested). Further investigations using S. aureus NRS384 (USA300) and daptomycin demonstrated a 64-fold increase in the MIC after 55 passages (from 0.5 μg/ml to 32 μg/ml) with a >4-fold increase in the MIC obtained after only five passages. Sequencing analysis of selected isolates confirmed previously reported point mutations associated with daptomycin resistance. No cross-resistance to XF-73 was observed with the daptomycin-resistant strains, suggesting that whereas the two drugs act on the bacterial cell membrane, their specific site of action differs. XF-73 thus represents the first in a new class of antibacterial drugs, which (unlike the comparator antibiotics) after 55 passages exhibited a ≤4-fold increase in MIC against the strains tested. Antibacterial drugs with a low propensity for inducing bacterial resistance are much needed for the prevention and treatment of multidrug-resistant bacteria both within and outside the hospital setting.

Risk factors associated with mupirocin resistance in meticillin-resistant Staphylococcus aureus

Implementation of meticillin-resistant Staphylococcus aureus (MRSA) decolonisation programmes has been increasing and the emergence of mupirocin resistance has been reported. However, the patient-level risk factors associated with mupirocin resistance are not clear. In this study, independent predictors of mupirocin resistance in MRSA among Providence Veterans Affairs Medical Center patients with MRSA-positive culture dates between 1 July 2004 and 30 June 2008 were identified using a frequency-matched case-control study. Forty cases (mupirocin-resistant) were matched on culture date quarter and year to 270 controls (mupirocin-susceptible). The adjusted conditional logistic regression model identified three significant independent predictors associated with mupirocin resistance in MRSA: (1) exposure to mupirocin in the year prior to the culture date [odds ratio (OR): 9.84; 95% confidence interval (CI): 2.93-33.09]; (2) Pseudomonas aeruginosa infection in the year before the culture-related admission (4.85; 1.20-19.61); and (3) cefepime use in the year prior to culture (2.80; 1.03-7.58). In sensitivity analyses, previous mupirocin exposure was associated with low-level [minimum inhibitory concentration (MIC) 8-128mg/L; 23 cases, 202 controls; OR: 6.32; 95% CI: 1.58-25.33] and high-level (MIC ≥256mg/L; 17 cases, 151 controls; OR: 11.18; 95% CI: 1.89-66.30) mupirocin resistance. To our knowledge, this is the first case-control study to reveal a strong association between previous mupirocin exposure and subsequent mupirocin resistance in MRSA, with demonstrated robustness in low- and high-level mupirocin resistance. Mupirocin susceptibility monitoring is critical for facilities instituting decolonisation with mupirocin as increased use may reduce effectiveness through resistance.

Staphylococcus aureus: a continuously evolving and formidable pathogen in the neonatal intensive care unit

Staphylococcus aureus is a continuously evolving and formidable pathogen that has been a problem for both healthy and sick neonates for decades. Much focus over the past 20 years has been on hospital-associated methicillin-resistant S aureus (HA-MRSA); however, a global epidemic because of virulent community-associated MRSA (CA-MRSA) that has no "fitness cost" for carrying antibiotic-resistance genes has moved into neonatal intensive care units (NICUs). Recently, methicillin-susceptible S aureus has adopted some of the virulence factors of CA-MRSA and is an increasingly common cause of hospital-acquired infections in NICUs. This article reviews the changing epidemiology, clinical manifestations, and treatment of S aureus in neonates.

Mupirocin resistance related to increasing mupirocin use in clinical isolates of methicillin-resistant Staphylococcus aureus in a pediatric population

We investigated the proportion of methicillin-resistant Staphylococcus aureus (MRSA) isolates from pediatric patients demonstrating mupirocin resistance related to mupirocin use at our institution. No mupirocin resistance was found in 98% of isolates, whereas mupirocin prescriptions increased by 110%. Resistance rates remained low despite the increasing use of mupirocin.

Methicillin-resistant Staphylococcus aureus in Canada: a historical perspective and lessons learned

The history of methicillin-resistant Staphylococcus aureus (MRSA) in Canada has many similarities to MRSA evolution worldwide, but especially to that in the United States and United Kingdom. Reports of MRSA occurred as early as 1964, and community isolates were cited in the 1970s. Nosocomial outbreaks were becoming common by 1978 and flourished gradually thereafter. Endemic institutional MRSA became predominant in the 1990s, threatening large teaching hospitals in particular. In the last decade, both hospital-acquired and community-acquired MRSA have created major medical problems in Canada. More recently, an epidemic of Canadian community-acquired MRSA-10, has led to heightened public health concerns. Canadian contributions to MRSA science are numerous, with organized surveillance continuing to mature across the nation. A typing system for epidemic clones is now available and is being judiciously applied. Estimated costs for MRSA surveillance, treatment, and control are extraordinary, paralleling the dramatic rise in the number of MRSA isolations. Whereas surveillance continues to form an essential aspect of MRSA management, control, eradication, and overall diminution, MRSA reservoirs deserve much greater attention. Such efforts, however, must be as widely publicized in the community and in patient homes as they are in medical institutions responsible for both acute and long-term care.

Dialysis-associated peritonitis in children

Peritonitis remains a frequent complication of peritoneal dialysis in children and is the most common reason for technique failure. The microbiology is characterized by a predominance of Gram-positive organisms, with fungi responsible for less than 5% of episodes. Data collected by the International Pediatric Peritonitis Registry have revealed a worldwide variation in the bacterial etiology of peritonitis, as well as in the rate of culture-negative peritonitis. Risk factors for infection include young age, the absence of prophylactic antibiotics at catheter placement, spiking of dialysis bags, and the presence of a catheter exit-site or tunnel infection. Clinical symptoms at presentation are somewhat organism specific and can be objectively assessed with a Disease Severity Score. Whereas recommendations for empiric antibiotic therapy in children have been published by the International Society of Peritoneal Dialysis, epidemiologic data and antibiotic susceptibility data suggest that it may be desirable to take the patient- and center-specific history of microorganisms and their sensitivity patterns into account when prescribing initial therapy. The vast majority of patients are treated successfully and continue peritoneal dialysis, with the poorest outcome noted in patients with peritonitis secondary to Gram-negative organisms or fungi and in those with a relapsing infection.

Controlling antimicrobial resistance in the hospital

Most evidence-based methods to control the spread of antimicrobial resistance have been developed and applied to the hospital setting. Strategies to control the emergence and spread of antimicrobial resistance in hospitals can be categorized as either infection control or antibiotic stewardship strategies. Infection control is the discipline focused on preventing the spread of infections within the health care setting; antibiotic stewardship can help minimize the emergence of multidrug-resistant organisms by promoting prudent use of antibiotics. This article describes different infection control and antibiotic management strategies that can be used to control antimicrobial resistance in hospital settings.

Future gazing in the management of multiply drug-resistant Gram-positive infection

Gram-positive bacteria have evolved to become predominant health care associated pathogens. To meet this challenge, novel approaches to the development, prescribing, and control of antibiotics will be needed. Additional infection control methods must also be explored. This review discusses the challenges posed in particular by methicillin-resistant staphylococci and potential ways forward.

Mupirocin resistance among methicillin-resistant Staphylococcus aureus-colonized patients at admission to a tertiary care medical center

All patients admitted to our tertiary care hospital from 1 December 2007 to 10 June 2008 were screened for methicillin (meticillin)-resistant Staphylococcus aureus (MRSA) nasal colonization, and the isolates were tested for mupirocin susceptibility by using Etest. Mupirocin resistance (MR) was noted to occur in 3.4% of MRSA carriers, and high-level MR was noted to occur in 0.62% of carriers.