Duration of Colonization and Determinants of Earlier Clearance of Colonization With Methicillin-Resistant Staphylococcus aureus

Risk Factors of Recurrent Infection in Patients with Staphylococcus aureus Bacteremia: a Competing Risk Analysis

Although several clinical variables have been reported as risk factors for recurrence of Staphylococcus aureus infection, most studies have not considered competing risk events that may overestimate the risk. In this study, we performed competing risk analysis to identify risk factors related to 90-day recurrence in patients with S. aureus bacteremia (SAB) using a large cohort data from a single tertiary hospital in South Korea. All adults who experienced SAB during admission were prospectively enrolled from August 2008 to December 2019. After the day of the first positive blood culture, recurrence and all-cause mortality were assessed for 90 days. Recurrence was defined as a development of symptoms or signs of infection with or without repeated bacteremia after >7 days of negative blood culture and clinically apparent improvement. Subdistribution hazard ratios (sHR) for recurrence and all-cause mortality were estimated using Fine and Gray models. Of 1,725 SAB patients, including 885 cases (51.3%) of methicillin-resistant S. aureus (MRSA) bacteremia, 85 (5.0%) experienced recurrence during the study period. In a multivariate Fine and Gray regression model, the presence of a vascular graft (subdistribution HR [sHR], 3.48; 95% confidence interval [CI], 1.90-6.40), nasal MRSA carriage (sHR, 2.10; 95% CI, 1.28-3.44), methicillin resistance (sHR, 1.69; 95% CI, 1.00-2.84), and rifampicin resistance (sHR, 2.20; 95% CI, 1.12-4.33) were significantly associated with 90-day recurrence. In a large cohort of SAB patients with a high prevalence of MRSA, indwelling vascular graft, nasal MRSA carriage, methicillin resistance, and rifampicin resistance were potential risk factors for recurrence of S. aureus infection.

Stopping Hospital Infections With Environmental Services (SHINE): A Cluster-randomized Trial of Intensive Monitoring Methods for Terminal Room Cleaning on Rates of Multidrug-resistant Organisms in the Intensive Care Unit

BACKGROUND

Multidrug-resistant organisms (MDROs) frequently contaminate hospital environments. We performed a multicenter, cluster-randomized, crossover trial of 2 methods for monitoring of terminal cleaning effectiveness.

METHODS

Six intensive care units (ICUs) at 3 medical centers received both interventions sequentially, in randomized order. Ten surfaces were surveyed each in 5 rooms weekly, after terminal cleaning, with adenosine triphosphate (ATP) monitoring or an ultraviolet fluorescent marker (UV/F). Results were delivered to environmental services staff in real time with failing surfaces recleaned. We measured monthly rates of MDRO infection or colonization, including methicillin-resistant Staphylococcus aureus, Clostridioides difficile, vancomycin-resistant Enterococcus, and MDR gram-negative bacilli (MDR-GNB) during a 12-month baseline period and sequential 6-month intervention periods, separated by a 2-month washout. Primary analysis compared only the randomized intervention periods, whereas secondary analysis included the baseline.

RESULTS

The ATP method was associated with a reduction in incidence rate of MDRO infection or colonization compared with the UV/F period (incidence rate ratio [IRR] 0.876; 95% confidence interval [CI], 0.807-0.951; P = .002). Including the baseline period, the ATP method was associated with reduced infection with MDROs (IRR 0.924; 95% CI, 0.855-0.998; P = .04), and MDR-GNB infection or colonization (IRR 0.856; 95% CI, 0.825-0.887; P < .001). The UV/F intervention was not associated with a statistically significant impact on these outcomes. Room turnaround time increased by a median of 1 minute with the ATP intervention and 4.5 minutes with UV/F compared with baseline.

CONCLUSIONS

Intensive monitoring of ICU terminal room cleaning with an ATP modality is associated with a reduction of MDRO infection and colonization.

Comparative Effectiveness Study of Home-Based Interventions to Prevent CA-MRSA Infection Recurrence

Recurrent skin and soft tissue infections (SSTI) caused by Community-Associated Methicillin-Resistant Staphylococcus aureus (CA-MRSA) or Methicillin-Sensitive Staphylococcus aureus (CA-MSSA) present treatment challenges. This community-based trial examined the effectiveness of an evidence-based intervention (CDC Guidelines, topical decolonization, surface decontamination) to reduce SSTI recurrence, mitigate household contamination/transmission, and improve patient-reported outcomes. Participants (n = 186) were individuals with confirmed MRSA(+)/MSSA(+) SSTIs and their household members. During home visits; Community Health Workers/Promotoras provided hygiene instructions; a five-day supply of nasal mupirocin; chlorhexidine for body cleansing; and household disinfecting wipes (Experimental; EXP) or Usual Care Control (UC CON) pamphlets. Primary outcome was six-month SSTI recurrence from electronic health records (EHR). Home visits (months 0; 3) and telephone assessments (months 0; 1; 6) collected self-report data. Index patients and participating household members provided surveillance culture swabs. Secondary outcomes included household surface contamination; household member colonization and transmission; quality of life; and satisfaction with care. There were no significant differences in SSTI recurrence between EXP and UC in the intent-to-treat cohort (n = 186) or the enrolled cohort (n = 119). EXP participants showed reduced but non-significant colonization rates. EXP and UC did not differ in household member transmission, contaminated surfaces, or patient-reported outcomes. This intervention did not reduce clinician-reported MRSA/MSSA SSTI recurrence. Taken together with other recent studies that employed more intensive decolonization protocols, it is possible that a promotora-delivered intervention instructing treatment for a longer or repetitive duration may be effective and should be examined by future studies.

Environmental Methicillin-resistant Staphylococcus aureus Contamination, Persistent Colonization, and Subsequent Skin and Soft Tissue Infection

IMPORTANCE

The longitudinal association among persistent Staphylococcus aureus colonization, household environmental contamination, and recurrent skin and soft tissue infection (SSTI) is largely unexplored to date.

OBJECTIVES

To identify factors associated with persistent S aureus colonization and recurrent SSTI in households with children with community-associated methicillin-resistant S aureus (MRSA) SSTI.

DESIGN, SETTING, AND PARTICIPANTS

This 12-month prospective cohort study included 150 children with community-associated MRSA SSTI, 542 household contacts, and 154 pets enrolled from January 3, 2012, through October 20, 2015. A total of 5 quarterly home visits were made to 150 households in the St Louis, Missouri, region. Statistical analysis was performed from September 18, 2018, to January 7, 2020.

EXPOSURES

Covariates used in S aureus strain persistence and interval SSTI models included S aureus colonization and contamination measures, personal hygiene and sharing habits, health history, activities external to the home, and household characteristics (eg, cleanliness, crowding, home ownership, and pets). Serial samples to detect S aureus were collected from household members at 3 anatomic sites, from pets at 2 anatomic sites, and from environmental surfaces at 21 sites.

MAIN OUTCOMES AND MEASURES

Molecular epidemiologic findings of S aureus isolates were assessed via repetitive-sequence polymerase chain reaction. Individual persistent colonization was defined as colonization by an identical strain for 2 consecutive samplings. Longitudinal, multivariable generalized mixed-effects logistic regression models were used to assess factors associated with persistent S aureus personal colonization, environmental contamination, and interval SSTI.

RESULTS

Among 692 household members in 150 households, 326 (47%) were male and 366 (53%) were female, with a median age of 14.82 years (range, 0.05-82.25 years). Of 540 participants completing all 5 samplings, 213 (39%) were persistently colonized with S aureus, most often in the nares and with the strain infecting the index patient at enrollment. Nine pets (8%) were persistently colonized with S aureus. Participants reporting interval intranasal mupirocin application were less likely to experience persistent colonization (odds ratio [OR], 0.44; 95% credible interval [CrI], 0.30-0.66), whereas increasing strain-specific environmental contamination pressure was associated with increased individual persistent colonization (OR, 1.17; 95% CrI, 1.06-1.30). Strains with higher colonization pressure (OR, 1.47; 95% CrI, 1.25-1.71) and MRSA strains (OR, 1.57; 95% CrI, 1.16-2.19) were more likely to persist. Seventy-six index patients (53%) and 101 household contacts (19%) reported interval SSTIs. Individuals persistently colonized with MRSA (OR, 1.56; 95% CrI, 1.17-2.11), those with a history of SSTI (OR, 2.55; 95% CrI, 1.88-3.47), and index patients (OR, 1.54; 95% CrI, 1.07-2.23) were more likely to report an interval SSTI.

CONCLUSIONS AND RELEVANCE

The study findings suggest that recurrent SSTI is associated with persistent MRSA colonization of household members and contamination of environmental surfaces. Future studies may elucidate the effectiveness of specific combinations of personal decolonization and environmental decontamination efforts in eradicating persistent strains and mitigating recurrent SSTIs.

Effect of Treating Parents Colonized With Staphylococcus aureus on Transmission to Neonates in the Intensive Care Unit: A Randomized Clinical Trial

IMPORTANCE

Staphylococcus aureus is a leading cause of health care-associated infections in the neonatal intensive care unit (NICU). Parents may expose neonates to S aureus colonization, a well-established predisposing factor to invasive S aureus disease.

OBJECTIVE

To test whether treating parents with intranasal mupirocin and topical chlorhexidine compared with placebo would reduce transmission of S aureus from parents to neonates.

DESIGN, SETTING, AND PARTICIPANTS

Double-blinded randomized clinical trial in 2 tertiary NICUs in Baltimore, Maryland. Neonates (n = 236) with S aureus-colonized parent(s) were enrolled. The study period was November 7, 2014, through December 13, 2018.

INTERVENTIONS

Parents were assigned to intranasal mupirocin and 2% chlorhexidine-impregnated cloths (active treatment, n = 117) or petrolatum intranasal ointment and nonmedicated soap cloths (placebo, n = 119) for 5 days.

MAIN OUTCOMES AND MEASURES

The primary end point was concordant S aureus colonization by 90 days, defined as neonatal acquisition of an S aureus strain that was the same strain as a parental strain at time of screening. Secondary outcomes included neonatal acquisition of any S aureus strain and neonatal S aureus infections.

RESULTS

Among 236 randomized neonates, 208 were included in the analytic sample (55% male; 76% singleton births; mean birth weight, 1985 g [SD, 958 g]; 76% vaginal birth; mean parent age, 31 [SD, 7] years), of whom 18 were lost to follow-up. Among 190 neonates included in the analysis, 74 (38.9%) acquired S aureus colonization by 90 days, of which 42 (56.8%) had a strain concordant with a parental baseline strain. In the intervention and placebo groups, 13 of 89 neonates (14.6%) and 29 of 101 neonates (28.7%), respectively, acquired concordant S aureus colonization (risk difference, -14.1% [95% CI, -30.8% to -3.9%]; hazard ratio [HR], 0.43 [95.2% CI, 0.16 to 0.79]). A total of 28 of 89 neonates (31.4%) in the intervention group and 46 of 101 (45.5%) in the control group acquired any S aureus strain (HR, 0.57 [95% CI, 0.31 to 0.88]), and 1 neonate (1.1%) in the intervention group and 1 neonate (1.0%) in the control group developed an S aureus infection before colonization. Skin reactions in parents were common (4.8% intervention, 6.2% placebo).

CONCLUSIONS AND RELEVANCE

In this preliminary trial of parents colonized with S aureus, treatment with intranasal mupirocin and chlorhexidine-impregnated cloths compared with placebo significantly reduced neonatal colonization with an S aureus strain concordant with a parental baseline strain. However, further research is needed to replicate these findings and to assess their generalizability.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02223520.

Methicillin-resistant Staphylococcus aureus: an overview of basic and clinical research

Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most successful modern pathogens. The same organism that lives as a commensal and is transmitted in both health-care and community settings is also a leading cause of bacteraemia, endocarditis, skin and soft tissue infections, bone and joint infections and hospital-acquired infections. Genetically diverse, the epidemiology of MRSA is primarily characterized by the serial emergence of epidemic strains. Although its incidence has recently declined in some regions, MRSA still poses a formidable clinical threat, with persistently high morbidity and mortality. Successful treatment remains challenging and requires the evaluation of both novel antimicrobials and adjunctive aspects of care, such as infectious disease consultation, echocardiography and source control. In this Review, we provide an overview of basic and clinical MRSA research and summarize the expansive body of literature on the epidemiology, transmission, genetic diversity, evolution, surveillance and treatment of MRSA.

Impact of Decolonization Protocols and Recurrence in Pediatric MRSA Skin and Soft-Tissue Infections

BACKGROUND

Methicillin-resistant staphylococcus aureus (MRSA) colonization is associated with the development of skin and soft-tissue infection in children. Although MRSA decolonization protocols are effective in eradicating MRSA colonization, they have not been shown to prevent recurrent MRSA infections. This study analyzed the prescription of decolonization protocols, rates of MRSA abscess recurrence, and factors associated with recurrence.

MATERIALS AND METHODS

This study is a single-institution retrospective review of patients ≤18 y of age diagnosed with MRSA culture-positive abscesses who underwent incision and drainage (I&D) at a tertiary-care children's hospital. The prescription of an MRSA decolonization protocol was recorded. The primary outcome was MRSA abscess recurrence.

RESULTS

Three hundred ninety-nine patients with MRSA culture-positive abscesses who underwent I&D were identified. Patients with previous history of abscesses, previous MRSA infection groin/genital region abscesses, higher number of family members with a history of abscess/cellulitis or MRSA infection, and I&D by a pediatric surgeon were more likely to be prescribed decolonization. Decolonized patients did not have lower rates of recurrence. Recurrence was more likely to occur in patients with previous abscesses, previous MRSA infection, family history of abscesses, family history of MRSA infection, Hispanic ethnicity, and those with fever on admission.

CONCLUSIONS

MRSA decolonization did not decrease the rate of recurrence of MRSA abscesses in our patient cohort. Patients at high risk for MRSA recurrence such as personal or family history of abscess or MRSA infection, Hispanic ethnicity, or fever on admission did not benefit from decolonization.

Community-associated Methicillin-Resistant Staphylococcus aureus Infection Rates and Management among Student-Athletes

PURPOSE

Although community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) infections have reduced among inpatient populations, the incidence in athletics continues to range greatly dependent on the sport. Over the 2015 to 2016 and 2016 to 2017 school years, we assessed the annual CA-MRSA incidence, sport risk, referral practices, and management protocols or interventions among high school and intercollegiate athletics.

METHODS

This study targeted high school and intercollegiate athletic programs across the United States. For the 2015 to 2016 study, 269 athletic trainers completed a one-time questionnaire. In the 2016 to 2017 study, 217 athletic trainers reported data bimonthly during the academic year. Each questionnaire targeted demographic information, physician-confirmed CA-MRSA infection occurrence, and management of CA-MRSA infections and bacterial skin lesions.

RESULTS

The CA-MRSA infection incidence was 26.8 per 10,000 athletes (95% confidence interval [CI], 24-30) in 2015-2016 and 20.3 per 10,000 athletes (95% CI, 18-23) in 2016-2017. The CA-MRSA infection incidence was high in wrestling and football compared to the general student-athlete population. During the 2015 to 2016 study, the wrestling incidence rate was 248.3 per 10,000 (95% CI, 204-302); the football incidence rate was 71.0 per 10,000 (95% CI, 60-85). In the 2016 to 2017 study, the wrestling incidence rate was 100.0 per 10,000 (95% CI, 66-151); the football incidence rate was 81.8 per 10,000 (95% CI, 68-99). At least 23% of respondents denoted at least one physician-confirmed CA-MRSA infection within their populations (2015-2016, 39%, n = 105; 2016-2017, 23.5%, n = 51). In the 2015 to 2016 survey, respondents indicated that athlete education and environmental decontamination were the most used management steps (51.8%, n = 582).

CONCLUSIONS

Despite increased awareness of CA-MRSA, more educational efforts focusing on best practices and education are needed, especially with athletes and the medical community involved in their care.

Prevention Strategies for Recurrent Community-Associated Staphylococcus aureus Skin and Soft Tissue Infections

PURPOSE OF REVIEW

Staphylococcus aureus skin and soft tissue infections (SSTI) are a major source of morbidity. More than half of patients experiencing SSTI will have at least one recurrent infection. These infections frequently cluster in households. Given the burden these infections pose to patients and healthcare, prevention strategies are of major clinical importance and represent an active area of research. Bacterial colonization is frequently an early and critical step in the pathogenesis of infection. As such, strategies to prevent reinfection have aimed to decrease staphylococcal colonization of the skin and mucus membranes, a process referred to as decolonization.

RECENT FINDINGS

Treatment of acute SSTI with incision and drainage and systemic antibiotics is the mainstay of therapy for healing of the acute infection. Systemic antibiotics also provide benefit through reduced incidence of recurrent SSTI. Education for patients and families regarding optimization of personal and household hygiene measures, and avoidance of sharing personal hygiene items, is an essential component in prevention efforts. For patients experiencing recurrent SSTI, or in households in which multiple members have experienced SSTI, decolonization should be recommended for all household members. A recommended decolonization regimen includes application of intranasal mupirocin and antiseptic body washes with chlorhexidine or dilute bleach water baths. For patients who continue to experience recurrent SSTI, periodic decolonization should be considered. Personal decolonization with topical antimicrobials and antiseptics reduces the incidence of recurrent S. aureus SSTI. Future avenues for investigation include strategies for household environmental decontamination as well as manipulation of the host microbiota.

In-hospital costs of community-acquired colonization with multidrug-resistant organisms at a German teaching hospital

Background

Antibiotic resistance is a challenge in the management of infectious diseases and can cause substantial cost. Even without the onset of infection, measures must be taken, as patients colonized with multi-drug resistant (MDR) pathogens may transmit the pathogen. We aim to quantify the cost of community-acquired MDR colonizations using routine data from a German teaching hospital.

Methods

All 2006 cases of documented MDR colonization at hospital admission recorded from 2011 to 2014 are matched to 7917 unexposed controls with the same primary diagnosis. Cases with an onset MDR infection are excluded from the analysis. Routine data on costs per case is analysed for three groups of MDR bacteria: Methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococcus (VRE), and multidrug-resistant gram-negative bacteria (MDR-GN). Multivariate analyses are conducted to adjust for potential confounders.

Results

After controlling for main diagnosis group, age, sex, and Charlson Comorbidity Index, MDR colonization is associated with substantial additional costs from the healthcare perspective (€1480.9, 95%CI €1286.4–€1675.5). Heterogeneity between pathogens remains. Colonization with MDR-GN leads to the largest cost increase (€1966.0, 95%CI €1634.6–€2297.4), followed by MRSA with €1651.3 (95%CI €1279.1–€2023.6), and VRE with €879.2 (95%CI €604.1–€1154.2). At the same time, MDR-GN is associated with additional reimbursements of €887.8 (95%CI €722.1–€1053.6), i.e. costs associated with MDR-colonization exceed reimbursement.

Conclusions

Even without the onset of invasive infection, documented MDR-colonization at hospital admission is associated with increased hospital costs, which are not fully covered within the German DRG-based hospital payment system.

Electronic supplementary material

The online version of this article (10.1186/s12913-018-3549-0) contains supplementary material, which is available to authorized users.

Multidrug-Resistant Organisms and Contact Precautions

Most nurses know when to start precautions, but for how long should they continue?

Staphylococcus aureus

Staphylococcus aureus is a bacterium that can cause a variety of illnesses through suppurative or nonsuppurative (toxin-mediated) means. S aureus is a common cause of skin and skin structure infections as well as osteoarticular infections in the pediatric population. S aureus is also identified in cases of septicemia, infective endocarditis, pneumonia, ocular infections, and central nervous system infections. To design appropriate empirical therapy, pediatricians should be knowledgeable about the resistance patterns of S aureus in their communities, including methicillin and clindamycin resistance. This article reviews the microbiology, colonization and transmission, and antibiotic resistance of and clinical diseases caused by S aureus.

The majority of MRSA colonized children not given eradication treatment are still colonized one year later. Systemic antibiotics improve the eradication rate

BACKGROUND

Colonization with methicillin-resistant Staphylococcus aureus (MRSA) can cause endogenously derived infections and be a source of transmission to other people. Neither colonization time of asymptomatic MRSA colonization nor the effect of treatment aiming at MRSA eradication in children has been thoroughly investigated.

METHODS

Two hundred ninety-three children <18 years in the mandatory follow-up program for MRSA-carriers in Malmö, Sweden were evaluated. Samples from the throat, nares, perineum and skin lesions from each child were screened for MRSA with a PCR-based broth enrichment method. PVL presence and spa-type were evaluated in a majority of cases. The sampling was repeated approximately every 6 month after initial detection. When three consecutive sets of negative samples during at least a 6-month period were obtained, the MRSA was considered permanently eradicated. MRSA eradication treatment given, on clinical grounds during follow-up, was noted.

RESULTS

One year after detection 62% of the untreated children were still MRSA positive and after 2 years 28%. MRSA throat colonization and having MRSA positive household contacts significantly prolonged the observed colonization time. Topical MRSA eradication treatment was successful in 36% of cases and in 65% if systemic antibiotics were added. Presence of PVL correlated with shorter observed colonization time in the older age group and with increased eradication success among throat carriers.

CONCLUSION

MRSA throat colonization and having MRSA positive household contacts prolongs the time of MRSA colonization in children. Systemic antibiotics enhance the effect of MRSA eradication treatment.

Impact of systemic antimicrobial therapy on mucosal staphylococci in a population of dogs in Northwest England

BACKGROUND

Antimicrobial-resistant bacteria are increasingly isolated from veterinary patients.

OBJECTIVES

To determine risk factors for antimicrobial resistance (AMR) among canine mucosal staphylococci following routine antimicrobial treatment with cefalexin (CFX), clavulanate-amoxicillin (AC), cefovecin (CVN), clindamycin (CD) or a fluoroquinolone (FQ).

ANIMALS

Mucosal swab samples (n = 463) were collected from 127 dogs pre-treatment, immediately, and at one- and three-months post-treatment.

METHODS

Staphylococci were identified phenotypically and biochemically as coagulase negative (CoNS) or coagulase positive (CoPS); CoPS were speciated by nuc gene PCR. Antimicrobial susceptibility was determined using disc diffusion and mecA gene carriage by PCR. Multilevel, multivariable models examined associations between risk factors and presence/absence of CoPS, meticillin resistance (MR), multidrug-resistance (MDR) and fluoroquinolone resistance (FQR).

RESULTS

The percentage of samples with CoNS increased and with CoPS (including S. pseudintermedius) decreased immediately post-treatment with CFX, CVN and CD (P ≤ 0.001) and one month post-treatment with CD (P = 0.003). By three months post-treatment, there was no significant difference compared to pre-treatment samples. Immediately post-treatment with FQs there was significantly increased risk of isolating MRS (P = 0.002), MDR (P = 0.002) or FQR (P = 0.013) staphylococci and of MDR following CFX treatment (P = 0.019). The percentage of samples with AMR staphylococci declined from immediately to three months post-treatment and there was no significant difference between resistance prevalence at one or three months post-treatment for most AMR traits and treatment groups. Exceptions include increased MDR following FQ (P = 0.048) or CFX (P = 0.021), at one and three months post-treatment, respectively.

CONCLUSIONS AND CLINICAL IMPORTANCE

Systemic antimicrobials impact on mucosal staphylococci. Immediately after therapy, the mucosa may be a reservoir for AMR staphylococci that are a source of mobile genetic elements carrying AMR genes.

Impact of Systemic Antibiotics on Staphylococcus aureus Colonization and Recurrent Skin Infection

Background

Staphylococcus aureus colonization poses risk for subsequent skin and soft tissue infection (SSTI). We hypothesized that including systemic antibiotics in the management of S. aureus SSTI, in conjunction with incision and drainage, would reduce S. aureus colonization and incidence of recurrent infection.

Methods

We prospectively evaluated 383 children with S. aureus SSTI requiring incision and drainage and S. aureus colonization in the anterior nares, axillae, or inguinal folds at baseline screening. Systemic antibiotic prescribing at the point of care was recorded. Repeat colonization sampling was performed within 3 months (median, 38 days; interquartile range, 22-50 days) in 357 participants. Incidence of recurrent infection was ascertained for up to 1 year.

Results

Participants prescribed guideline-recommended empiric antibiotics for purulent SSTI were less likely to remain colonized at follow-up sampling (adjusted hazard ratio [aHR], 0.49; 95% confidence interval [CI], .30-.79) and less likely to have recurrent SSTI (aHR, 0.57; 95% CI, .34-.94) than those not receiving guideline-recommended empiric antibiotics for their SSTI. Additionally, participants remaining colonized at repeat sampling were more likely to report a recurrent infection over 12 months (aHR, 2.37; 95% CI, 1.69-3.31). Clindamycin was more effective than trimethoprim-sulfamethoxazole (TMP-SMX) in eradicating S. aureus colonization (44% vs 57% remained colonized, P = .03) and preventing recurrent SSTI (31% vs 47% experienced recurrence, P = .008).

Conclusions

Systemic antibiotics, as part of acute SSTI management, impact S. aureus colonization, contributing to a decreased incidence of recurrent SSTI. The mechanism by which clindamycin differentially affects colonization and recurrent SSTI compared to TMP-SMX warrants further study.

Multidrug and Mupirocin Resistance in Environmental Methicillin-Resistant Staphylococcus aureus (MRSA) Isolates from Homes of People Diagnosed with Community-Onset MRSA Infection

Patients with community-onset (CO) methicillin-resistant Staphylococcus aureus (MRSA) infections contribute to MRSA contamination of the home environment and may be reexposed to MRSA strains from this reservoir. This study evaluates One Health risk factors, which focus on the relationship between humans, animals, and the environment, for the increased prevalence of multiple antimicrobial-resistant MRSA isolates in the home environment. During a trial of patients with CO-MRSA infection, MRSA was isolated from the household environment at the baseline and 3 months later, following randomization of patients and household members to mupirocin-based decolonization therapy or an education control group. Up to two environmental MRSA isolates collected at each visit were tested. MRSA isolates were identified in 68% (65/95) of homes at the baseline (n = 104 isolates) and 51% (33/65) of homes 3 months later (n = 56 isolates). The rates of multidrug resistance (MDR) were 61% among isolates collected at the baseline and 55% among isolates collected at the visit 3 months later. At the baseline, 100% (14/14) of MRSA isolates from rural homes were MDR. While antimicrobial use by humans or pets was associated with an increased risk for the isolation of MDR MRSA from the environment, clindamycin use was not associated with an increased risk for the isolation of MDR MRSA. Incident low-level mupirocin-resistant MRSA strains were isolated at 3 months from 2 (5%) of 39 homes that were randomized to mupirocin treatment but none of the control homes. Among patients recently treated for a CO-MRSA infection, MRSA and MDR MRSA were common contaminants in the home environment. This study contributes to evidence that occupant use of antimicrobial drugs, except for clindamycin, is associated with MDR MRSA in the home environmental reservoir. (This study has been registered at ClinicalTrials.gov under registration no. NCT00966446.)IMPORTANCE MRSA is a common bacterial agent implicated in skin and soft tissue infections (SSTIs) in both community and health care settings. Patients with CO-MRSA infections contribute to environmental MRSA contamination in these settings and may be reexposed to MRSA strains from these reservoirs. People interact with natural and built environments; therefore, understanding the relationships between humans and animals as well as the characteristics of environmental reservoirs is important to advance strategies to combat antimicrobial resistance. Household interactions may influence the frequency and duration of exposure, which in turn may impact the duration of MRSA colonization or the probability for recurrent colonization and infection. Therefore, MRSA contamination of the home environment may contribute to human and animal recolonization and decolonization treatment failure. The aim of this study was to evaluate One Health risk factors that may be amenable to intervention and may influence the recovery of MDR and mupirocin resistance in CO-MRSA isolates.

Methodologic considerations of household-level methicillin-resistant Staphylococcus aureus decolonization among persons living with HIV

BACKGROUND

People living with HIV (PLWH) have a higher prevalence of methicillin-resistant Staphylococcus aureus (MRSA) colonization and likelihood of recurrent infection than the general population. Simultaneously treating MRSA-colonized household members may improve success with MRSA decolonization strategies. This article describes a pilot trial testing household-level MRSA decolonization and documents methodologic and pragmatic challenges of this approach.

METHODS

We conducted a randomized controlled trial of individual versus individual-plus-household MRSA decolonization to reduce recurrent MRSA. PLWH with a history of MRSA who are patients of an urban HIV clinic received a standard MRSA decolonization regimen. MRSA colonization at 6 months was the primary outcome.

RESULTS

One hundred sixty-six patients were referred for MRSA screening; 77 (46%) enrolled. Of those, 28 (36%) were colonized with MRSA and identified risk factors consistent with the published literature. Eighteen were randomized and 13 households completed the study.

CONCLUSIONS

This is the first study to report on a household-level MRSA decolonization among PLWH. Challenges included provider referral, HIV stigma, confidentiality concerns over enrolling households, and dynamic living situations. Although simultaneous household MRSA decolonization may reduce recolonization, recruitment and retention challenges specific to PLWH limit the ability to conduct household-level research. Efforts to minimize these barriers are needed to inform evidence-based practice.

Factors associated with persistent colonisation with methicillin-resistant Staphylococcus aureus

We conducted a prospective cohort study between 1 January 2010 and 31 December 2012 at five adult and paediatric academic medical centres to identify factors associated with persistent methicillin-resistant Staphylococcus aureus (MRSA) colonisation. Adults and children presenting to ambulatory settings with a MRSA skin and soft tissue infection (i.e. index cases), along with household members, performed self-sampling for MRSA colonisation every 2 weeks for 6 months. Clearance of colonisation was defined as two consecutive negative sampling periods. Subjects without clearance by the end of the study were considered persistently colonised and compared with those who cleared colonisation. Of 243 index cases, 48 (19·8%) had persistent colonisation and 110 (45·3%) cleared colonisation without recurrence. Persistent colonisation was associated with white race (odds ratio (OR), 4·90; 95% confidence interval (CI), 1·38-17·40), prior MRSA infection (OR 3·59; 95% CI 1·05-12·35), colonisation of multiple sites (OR 32·7; 95% CI 6·7-159·3). Conversely, subjects with persistent colonisation were less likely to have been treated with clindamycin (OR 0·28; 95% CI 0·08-0·99). Colonisation at multiple sites is a risk factor for persistent colonisation and may require more targeted decolonisation efforts. The specific effect of clindamycin on MRSA colonisation needs to be elucidated.

Decolonization in Prevention of Health Care-Associated Infections

Colonization with health care-associated pathogens such as Staphylococcus aureus, enterococci, Gram-negative organisms, and Clostridium difficile is associated with increased risk of infection. Decolonization is an evidence-based intervention that can be used to prevent health care-associated infections (HAIs). This review evaluates agents used for nasal topical decolonization, topical (e.g., skin) decolonization, oral decolonization, and selective digestive or oropharyngeal decontamination. Although the majority of studies performed to date have focused on S. aureus decolonization, there is increasing interest in how to apply decolonization strategies to reduce infections due to Gram-negative organisms, especially those that are multidrug resistant. Nasal topical decolonization agents reviewed include mupirocin, bacitracin, retapamulin, povidone-iodine, alcohol-based nasal antiseptic, tea tree oil, photodynamic therapy, omiganan pentahydrochloride, and lysostaphin. Mupirocin is still the gold standard agent for S. aureus nasal decolonization, but there is concern about mupirocin resistance, and alternative agents are needed. Of the other nasal decolonization agents, large clinical trials are still needed to evaluate the effectiveness of retapamulin, povidone-iodine, alcohol-based nasal antiseptic, tea tree oil, omiganan pentahydrochloride, and lysostaphin. Given inferior outcomes and increased risk of allergic dermatitis, the use of bacitracin-containing compounds cannot be recommended as a decolonization strategy. Topical decolonization agents reviewed included chlorhexidine gluconate (CHG), hexachlorophane, povidone-iodine, triclosan, and sodium hypochlorite. Of these, CHG is the skin decolonization agent that has the strongest evidence base, and sodium hypochlorite can also be recommended. CHG is associated with prevention of infections due to Gram-positive and Gram-negative organisms as well as Candida. Conversely, triclosan use is discouraged, and topical decolonization with hexachlorophane and povidone-iodine cannot be recommended at this time. There is also evidence to support use of selective digestive decontamination and selective oropharyngeal decontamination, but additional studies are needed to assess resistance to these agents, especially selection for resistance among Gram-negative organisms. The strongest evidence for decolonization is for use among surgical patients as a strategy to prevent surgical site infections.

The Effect of Total Household Decolonization on Clearance of Colonization With Methicillin-Resistant Staphylococcus aureus

OBJECTIVE To determine the impact of total household decolonization with intranasal mupirocin and chlorhexidine gluconate body wash on recurrent methicillin-resistant Staphylococcus aureus (MRSA) infection among subjects with MRSA skin and soft-tissue infection. DESIGN Three-arm nonmasked randomized controlled trial. SETTING Five academic medical centers in Southeastern Pennsylvania. PARTICIPANTS Adults and children presenting to ambulatory care settings with community-onset MRSA skin and soft-tissue infection (ie, index cases) and their household members. INTERVENTION Enrolled households were randomized to 1 of 3 intervention groups: (1) education on routine hygiene measures, (2) education plus decolonization without reminders (intranasal mupirocin ointment twice daily for 7 days and chlorhexidine gluconate on the first and last day), or (3) education plus decolonization with reminders, where subjects received daily telephone call or text message reminders. MAIN OUTCOME MEASURES Owing to small numbers of recurrent infections, this analysis focused on time to clearance of colonization in the index case. RESULTS Of 223 households, 73 were randomized to education-only, 76 to decolonization without reminders, 74 to decolonization with reminders. There was no significant difference in time to clearance of colonization between the education-only and decolonization groups (log-rank P=.768). In secondary analyses, compliance with decolonization was associated with decreased time to clearance (P=.018). CONCLUSIONS Total household decolonization did not result in decreased time to clearance of MRSA colonization among adults and children with MRSA skin and soft-tissue infection. However, subjects who were compliant with the protocol had more rapid clearance Trial registration. ClinicalTrials.gov identifier: NCT00966446 Infect Control Hosp Epidemiol 2016;1-8.

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.

Association of Environmental Contamination in the Home With the Risk for Recurrent Community-Associated, Methicillin-Resistant Staphylococcus aureus Infection

IMPORTANCE

The role of environmental contamination in recurrent Staphylococcus aureus infections within households and its potential effect on intervention strategies has been debated recently.

OBJECTIVE

To assess whether household environmental contamination increases the risk for recurrent infection among individuals with a community-associated methicillin-resistant S aureus (MRSA) infection.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study was conducted from November 1, 2011, to June 30, 2014, in the Columbia University Medical Center catchment area. All patients within 72 hours of presentation with skin or soft-tissue infections and blood, urine, or sputum cultures positive for MRSA were identified. Two hundred sixty-two patients met study inclusion criteria; 83 of these (31.7%) agreed to participate (index patients) with 214 household members. Participants were followed up for 6 months, and 62 of the 83 households (74.7%) completed follow-up. Participants and researchers were blinded to exposure status throughout the study. Follow-up was completed on June 30, 2014, and data were assessed from July 1, 2014, to February 19, 2016.

EXPOSURE

Concordant environmental contamination, defined as having an isolate with the identical staphylococcal protein A and staphylococcal chromosomal cassette mec type or antibiogram type as the index patient's clinical isolate, present on 1 or more environmental surfaces at the time of a home visit to the index patient after infection.

MAIN OUTCOMES AND MEASURES

Index recurrent infection, defined as any self-reported infection among the index patients during follow-up.

RESULTS

One patient did not complete any follow-up. Of the remaining 82 index patients, 53 (64.6%) were female and 59 (72.0%) were Hispanic. The mean age was 30 (SD, 20; range, 1-79) years. Forty-nine of 61 MRSA infections where the clinical isolate could be obtained (80.3%) were due to the epidemic strain USA300. Among the 82 households in which a patient had an index MRSA infection, the clinical isolate was present in the environment in 20 (24.4%) and not found in 62 (75.6%). Thirty-five patients (42.7%) reported a recurrent infection during follow-up, of whom 15 (42.9%) required hospitalization. Thirteen recurrent infections were from the 20 households (65.0%) with and 22 were from the 62 households (35.5%) without environmental contamination (P = .04). Environmental contamination increased the rate of index recurrent infection (incident rate ratio, 2.05; 95% CI, 1.03-4.10; P = .04).

CONCLUSIONS AND RELEVANCE

Household environmental contamination was associated with an increased rate of recurrent infection. Environmental decontamination should be considered as a strategy to prevent future MRSA infections, particularly among households where an infection has occurred.

The Impact of Methicillin-Resistant Staphylococcus aureus (MRSA) and Vancomycin-Resistant Enterococcus (VRE) Flags on Hospital Operations

OBJECTIVE To determine the impact of methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus (MRSA/VRE) designations, or flags, on selected hospital operational outcomes. DESIGN Retrospective cohort study of inpatients admitted to the Massachusetts General Hospital during 2010-2011. METHODS Operational outcomes were time to bed arrival, acuity-unrelated within-hospital transfers, and length of stay. Covariates considered included demographic and clinical characteristics: age, gender, severity of illness on admission, admit day of week, residence prior to admission, hospitalization within the prior 30 days, clinical service, and discharge destination. RESULTS Overall, 81,288 admissions were included. After adjusting for covariates, patients with a MRSA/VRE flag at the time of admission experienced a mean delay in time to bed arrival of 1.03 hours (9.63 hours [95% CI, 9.39-9.88] vs 8.60 hours [95% CI, 8.47-8.73]). These patients had 1.19 times the odds of experiencing an acuity-unrelated within-hospital transfer [95% CI, 1.13-1.26] and a mean length of stay 1.76 days longer (7.03 days [95% CI, 6.82-7.24] vs 5.27 days [95% CI, 5.15-5.38]) than patients with no MRSA/VRE flag. CONCLUSIONS MRSA/VRE designation was associated with delays in time to bed arrival, increased likelihood of acuity-unrelated within-hospital transfers and extended length of stay. Efforts to identify patients who have cleared MRSA/VRE colonization are critically important to mitigate inefficient use of resources and to improve inpatient flow. Infect Control Hosp Epidemiol 2016;37:782-790.

Impact of rapid screening for discontinuation of methicillin-resistant Staphylococcus aureus contact precautions

BACKGROUND

A history of methicillin-resistant Staphylococcus aureus (MRSA) is a determinant of inpatient bed assignment.

METHODS

We assessed outcomes associated with rapid testing and discontinuation of MRSA contact precautions (CP) in a prospective cohort study of polymerase chain reaction (PCR)-based screening in the Emergency Department (ED) of Massachusetts General Hospital. Eligible patients had a history of MRSA and were assessed and enrolled if documented off antibiotics with activity against MRSA and screened for nasal colonization (subject visit). PCR-negative subjects had CP discontinued; the primary outcome was CP discontinuation. We identified semiprivate rooms in which a bed was vacant owing to the CP status of the study subject, calculated the hours of vacancy, and compared idle bed-hours by PCR results. Program costs were compared with predicted revenue.

RESULTS

There were 2864 eligible patients, and 648 (22.6%) subject visits were enrolled. Of these, 65.1% (422/648) were PCR-negative and had CP discontinued. PCR-negative subjects had fewer idle bed-hours compared with PCR-positive subjects (28.6 ± 25.2 vs 75.3 ± 70.5; P < .001). The expected revenues from occupied idle beds and averted CP costs ranged from $214,160 to $268,340, and exceeded the program costs.

CONCLUSION

A program of targeted PCR-based screening for clearance of MRSA colonization resulted in expected revenues and decreased CP costs that outweighed programmatic costs.

Fluoroquinolone Impact on Nasal Methicillin-Resistant and Methicillin-Sensitive Staphylococcus aureus Colonization Durations in Neurologic Long-Term-Care Facilities

Staphylococcus aureus nasal carriage is a risk factor for subsequent infection. Estimates of colonization duration vary widely among studies, and factors influencing the time to loss of colonization, especially the impact of antibiotics, remain unclear. We conducted a prospective study on patients naive for S. aureus colonization in 4 French long-term-care facilities. Data on nasal colonization status and potential factors for loss of colonization were collected weekly. We estimated methicillin-resistant S. aureus (MRSA) and methicillin-sensitive S. aureus (MSSA) colonization durations using the Kaplan-Meier method and investigated factors for loss of colonization using shared-frailty Cox proportional hazards models. A total of 285 S. aureus colonization episodes were identified in 149 patients. The median time to loss of MRSA or MSSA colonization was 3 weeks (95% confidence interval, 2 to 8 weeks) or 2 weeks (95% confidence interval, 2 to 3 weeks), respectively. In multivariable analyses, the methicillin resistance phenotype was not associated with S. aureus colonization duration (P = 0.21); the use of fluoroquinolones (hazard ratio, 3.37; 95% confidence interval, 1.31 to 8.71) and having a wound positive for a nonnasal strain (hazard ratio, 2.17; 95% confidence interval, 1.15 to 4.07) were associated with earlier loss of MSSA colonization, while no factor was associated with loss of MRSA colonization. These results suggest that the methicillin resistance phenotype does not influence the S. aureus colonization duration and that fluoroquinolones are associated with loss of MSSA colonization but not with loss of MRSA colonization.

Genome sequencing reveals strain dynamics of methicillin-resistant Staphylococcus aureus in the same household in the context of clinical disease in a person and a dog

The strain dynamics of methicillin-resistant Staphylococcus aureus (MRSA) isolates from people and the household dog were investigated. The isolates were identified in the context of a randomized controlled trial that tested household-wide decolonization of people. Genotypic comparison of MRSA isolates obtained from two household members, the dog, and home surfaces over a three-month period failed to implicate the pet or the home environment in recurrent colonization of the household members. However, it did implicate the pet's bed in exposure of the dog prior to the dog's infection. Whole genome sequencing was performed to differentiate the isolates. This report also describes introduction of diverse strains of MRSA into the household within six weeks of cessation of harmonized decolonization treatment of people and treatment for infection in the dog. These findings suggest that community sources outside the home may be important for recurrent MRSA colonization or infection.

The molecular epidemiology of incident methicillin-resistant Staphylococcus aureus cases among hospitalized patients in Alberta, Canada: a retrospective cohort study

BACKGROUND

Infection Prevention and Control (IPC) surveillance for incident methicillin-resistant Staphylococcus aureus (MRSA) in hospitalized patients is performed in a complete provincial surveillance network of all acute care facilities in Alberta, Canada. IPC surveillance is centralized using a web-based data entry platform so that each patient is counted only once. All diagnostic laboratories submit the first clinical MRSA isolate associated with a patient without previous MRSA positive clinical cultures in the preceding year to the Provincial Laboratory for Public Health (ProvLab) for molecular typing. This study will investigate the relationship between the IPC epidemiological classification based on time of detection following admission to hospital (Hospital Acquired and Community Associated) and the matched laboratory MRSA surveillance data using a retrospective cohort study design.

METHODS

Incident IPC MRSA cases were classified according to IPC epidemiologic definitions. DNA sequencing of the Staphylococcus protein A (spa) gene and pulsed-field gel electrophoresis (PFGE) typing was performed. IPC MRSA surveillance data were matched to the ProvLab molecular surveillance data. Univariate comparisons of proportions were performed for categorical variables and the Student's t test for continuous variables.

RESULTS

MRSA molecular typing data were available for matching for 46.7 % (2248/4818) of incident IPC cases. There was agreement in definitions for traditional nosocomial clones (USA100/CMRSA2) with Hospital Acquired (HA)-MRSA (65.1 % of all IPC HA-MRSA) and traditional community clones (USA400/CMRSA7 and USA300/CMRSA10) with Community Acquired (CA)-MRSA (62.4 % of CA-MRSA). However, we observed discordance for both traditional nosocomial/CA-MRSA (30.4 % of CA-MRSA) and for traditional community/HA-MRSA (26.9 % of HA-MRSA).

CONCLUSIONS

We note agreement between traditional nosocomial clones and HA-MRSA, and traditional community clones and CA-MRSA. However, approximately one-quarter of HA-MRSA are those of traditional community clones while approximately one-third of CA-MRSA are those of traditional nosocomial clones. Collaborative provincial MRSA surveillance is important as the distinction between IPC case attribution in acute care settings and the historical definitions of MRSA clones as community- or healthcare-associated have blurred.

Staphylococcus aureus infections: transmission within households and the community

Staphylococcus aureus, both methicillin susceptible and resistant, are now major community-based pathogens worldwide. The basis for this is multifactorial and includes the emergence of epidemic clones with enhanced virulence, antibiotic resistance, colonization potential, or transmissibility. Household reservoirs of these unique strains are crucial to their success as community-based pathogens. Staphylococci become resident in households, either as colonizers or environmental contaminants, increasing the risk for recurrent infections. Interactions of household members with others in different households or at community sites, including schools and daycare facilities, have a critical role in the ability of these strains to become endemic. Colonization density at these sites appears to have an important role in facilitating transmission. The integration of research tools, including whole-genome sequencing (WGS), mathematical modeling, and social network analysis, has provided additional insight into the transmission dynamics of these strains. Thus far, interventions designed to reduce recurrent infections among household members have had limited success, likely due to the multiplicity of potential sources for recolonization. The development of better strategies to reduce the number of household-based infections will depend on greater insight into the different factors that contribute to the success of these uniquely successful epidemic clones of S. aureus.