Using Self-Regulated Learning Microanalysis to Examine Regulatory Processes in Clerkship Students Engaged in Practice Questions.

Introduction: Self-regulated learning is a cyclical process of forethought, performance, and self-reflection that has been used as an assessment tool in medical education. No prior studies have evaluated SRL processes for answering multiple-choice questions (MCQs) and most evaluated one or two iterations of a non-MCQ task. SRL assessment during MCQs may elucidate reasons why learners are successful or not on these questions that are encountered repeatedly during medical education. Methods: Internal medicine clerkship students at three institutions participated in a SRL microanalytic protocol that targeted strategic planning, metacognitive monitoring, causal attributions, and adaptive inferences across seven MCQs. Responses were transcribed and coded according to previously published methods for microanalytic protocols. Results: Forty-four students participated. In the forethought phase, students commonly endorsed prioritizing relevant features as their diagnostic strategy (n = 20, 45%) but few mentioned higher-order diagnostic reasoning processes such as integrating clinical information (n = 5, 11%) or comparing/contrasting diagnoses (n = 0, 0%). However, in the performance phase, students' metacognitive processes included high frequencies of integration (n = 38, 86%) and comparing/contrasting (n = 24, 55%). In the self-reflection phase, 93% (n = 41) of students faulted their management reasoning and 84% (n = 37) made negative references to their abilities. Less than 10% (n = 4) of students indicated that they would adapt their diagnostic reasoning process for these questions. Discussion: This study describes in detail student self-regulatory processes during MCQs. We found that students engaged in higher-order diagnostic reasoning processes but were not explicit about it and seldom reflected critically on these processes after selecting an incorrect answer. Self-reflections focused almost exclusively on management reasoning and negative references to abilities which may decrease self-efficacy. Encouraging students to identify and evaluate diagnostic reasoning processes and make attributions to controllable factors may improve performance.

Effects of live and video simulation on clinical reasoning performance and reflection.

INTRODUCTION: In recent years, researchers have recognized the need to examine the relative effectiveness of different simulation approaches and the experiences of physicians operating within such environments. The current study experimentally examined the reflective judgments, cognitive processing, and clinical reasoning performance of physicians across live and video simulation environments. METHODS: Thirty-eight physicians were randomly assigned to a live scenario or video case condition. Both conditions encompassed two components: (a) patient encounter and (b) video reflection activity. Following the condition-specific patient encounter (i.e., live scenario or video), the participants completed a Post Encounter Form (PEF), microanalytic questions, and a mental effort question. Participants were then instructed to re-watch the video (i.e., video condition) or a video recording of their live patient encounter (i.e., live scenario) while thinking aloud about how they came to the diagnosis and management plan. RESULTS: Although significant differences did not emerge across all measures, physicians in the live scenario condition exhibited superior performance in clinical reasoning (i.e., PEF) and a distinct profile of reflective judgments and cognitive processing. Generally, the live condition participants focused more attention on aspects of the clinical reasoning process and demonstrated higher level cognitive processing than the video group. CONCLUSIONS: The current study sheds light on the differential effects of live scenario and video simulation approaches. Physicians who engaged in live scenario simulations outperformed and showed a distinct pattern of cognitive reactions and judgments compared to physicians who practiced their clinical reasoning via video simulation. Additionally, the current study points to the potential advantages of video self-reflection following live scenarios while also shedding some light on the debate regarding whether video-guided reflection, specifically, is advantageous. The utility of context-specific, micro-level assessments that incorporate multiple methods as physicians complete different parts of clinical tasks is also discussed.

First-year medical students' calibration bias and accuracy across clinical reasoning activities.

To be safe and effective practitioners and learners, medical professionals must be able to accurately assess their own performance to know when they need additional help. This study explored the metacognitive judgments of 157 first-year medical students; in particular, the study examined students' self-assessments or calibration as they engaged in a virtual-patient simulation targeting clinical reasoning practices. Examining two key subtasks of a patient encounter, history (Hx) and physical exam (PE), the authors assessed the level of variation in students' behavioral performance (i.e., effectiveness and efficiency) and judgments of performance (i.e., calibration bias and accuracy) across the two subtasks. Paired t tests revealed that the Hx subtask was deemed to be more challenging than the PE subtask when viewed in terms of both actual and perceived performance. In addition to students performing worse on the Hx subtask than PE, they also perceived that they performed less well for Hx. Interestingly, across both subtasks, the majority of participants overestimated their performance (98% of participants for Hx and 95% for PE). Correlation analyses revealed that the participants' overall level of accuracy in metacognitive judgments was moderately stable across the Hx and PE subtasks. Taken together, findings underscore the importance of assessing medical students' metacognitive judgments at different points during a clinical encounter.

Clinical Reasoning Assessment Methods: A Scoping Review and Practical Guidance.

PURPOSE: An evidence-based approach to assessment is critical for ensuring the development of clinical reasoning (CR) competence. The wide array of CR assessment methods creates challenges for selecting assessments fit for the purpose; thus, a synthesis of the current evidence is needed to guide practice. A scoping review was performed to explore the existing menu of CR assessments. METHOD: Multiple databases were searched from their inception to 2016 following PRISMA guidelines. Articles of all study design types were included if they studied a CR assessment method. The articles were sorted by assessment methods and reviewed by pairs of authors. Extracted data were used to construct descriptive appendixes, summarizing each method, including common stimuli, response formats, scoring, typical uses, validity considerations, feasibility issues, advantages, and disadvantages. RESULTS: A total of 377 articles were included in the final synthesis. The articles broadly fell into three categories: non-workplace-based assessments (e.g., multiple-choice questions, extended matching questions, key feature examinations, script concordance tests); assessments in simulated clinical environments (objective structured clinical examinations and technology-enhanced simulation); and workplace-based assessments (e.g., direct observations, global assessments, oral case presentations, written notes). Validity considerations, feasibility issues, advantages, and disadvantages differed by method. CONCLUSIONS: There are numerous assessment methods that align with different components of the complex construct of CR. Ensuring competency requires the development of programs of assessment that address all components of CR. Such programs are ideally constructed of complementary assessment methods to account for each method's validity and feasibility issues, advantages, and disadvantages.

Mycobacterium abscessus Complex Infections: A Retrospective Cohort Study.

BACKGROUND: Infections caused by Mycobacterium abscessus group strains are usually resistant to multiple antimicrobials and challenging to treat worldwide. We describe the risk factors, treatment, and clinical outcomes of patients in 2 large academic medical centers in the United States. METHODS: A retrospective cohort study of hospitalized adults with a positive culture for M. abscessus in Miami, Florida (January 1, 2011, to December 31, 2014). Demographics, comorbidities, the source of infection, antimicrobial susceptibilities, and clinical outcomes were analyzed. Early treatment failure was defined as death and/or infection relapse characterized either by persistent positive culture for M. abscessus within 12 weeks of treatment initiation and/or lack of radiographic improvement. RESULTS: One hundred eight patients were analyzed. The mean age was 50.81 ± 21.03 years, 57 (52.8%) were females, and 41 (38%) Hispanics. Eleven (10.2%) had end-stage renal disease, 34 (31.5%) were on immunosuppressive therapy, and 40% had chronic lung disease. Fifty-nine organisms (54.6%) were isolated in respiratory sources, 21 (19.4%) in blood, 10 (9.2%) skin and soft tissue, and 9 (8.3%) intra-abdominal. Antimicrobial susceptibility reports were available for 64 (59.3%) of the patients. Most of the isolates were susceptible to clarithromycin, amikacin, and tigecycline (93.8%, 93.8%, and 89.1%, respectively). None of the isolates were susceptible to trimethoprim/sulfamethoxazole, and only 1 (1.6%) was susceptible to ciprofloxacin. Thirty-six (33.3%) patients early failed treatment; of those, 17 (15.7%) died while hospitalized. On multivariate analysis, risk factors significantly associated with early treatment failure were disseminated infection (odds ratio [OR], 11.79; 95% confidence interval [CI], 1.53-81.69; P = .04), acute kidney injury (OR, 6.55; 95% CI, 2.4-31.25; P = .018), organ transplantation (OR, 2.37; 95% CI, 2.7-23.1; P = .005), immunosuppressive therapy (OR, 2.81; 95% CI, 1.6-21.4; P = .002), intravenous amikacin treatment (OR, 4.1; 95% CI, 0.9-21; P = .04), clarithromycin resistance (OR,79.5; 95% CI, 6.2-3717.1, P < .001), and presence of prosthetic device (OR, 5.43; 95% CI, 1.57-18.81; P = .008). Receiving macrolide treatment was found to be protective against early treatment failure (OR, 0.13; 95% CI, 0.002-1.8; P = .04). CONCLUSIONS: Our cohort of 108 M. abscessus complex isolates in Miami, Florida, showed an in-hospital mortality of 15.7%. Most infections were respiratory. Clarithromycin and amikacin were the most likely agents to be susceptible in vitro. Resistance to fluoroquinolone and trimethoprim/sulfamethoxazole was highly common. Macrolide resistance, immunosuppression, and renal disease were significantly associated with early treatment failure.

Multidimensional assessment of self-regulated learning with middle school math students.

This study examined the convergent and predictive validity of self-regulated learning (SRL) measures situated in mathematics. The sample included 100 eighth graders from a diverse, urban school district. Four measurement formats were examined including, 2 broad-based (i.e., self-report questionnaire and teacher ratings) and 2 task-specific measures (i.e., SRL microanalysis and behavioral traces). Convergent validity was examined across task-difficulty, and the predictive validity was examined across 3 mathematics outcomes: 2 measures of mathematical problem solving skill (i.e., practice session math problems, posttest math problems) and a global measure of mathematical skill (i.e., standardized math test). Correlation analyses were used to examine convergent validity and revealed medium correlations between measures within the same category (i.e., broad-based or task-specific). Relations between measurement classes were not statistically significant. Separate regressions examined the predictive validity of the SRL measures. While controlling all other predictors, a SRL microanalysis metacognitive-monitoring measure emerged as a significant predictor of all 3 outcomes and teacher ratings accounted for unique variance on 2 of the outcomes (i.e., posttest math problems and standardized math test). Results suggest that a multidimensional assessment approach should be considered by school psychologists interested in measuring SRL. (PsycINFO Database Record

Effects of the Self-Regulation Empowerment Program (SREP) on middle school students' strategic skills, self-efficacy, and mathematics achievement.

The current study examined the effectiveness of an applied self-regulated learning intervention (Self-Regulation Empowerment Program (SREP)) relative to an existing, school-based remedial mathematics intervention for improving the motivation, strategic skills, and mathematics achievement of academically at-risk middle school students. Although significant group differences in student self-regulated learning (SRL) were not observed when using self-report questionnaires, medium to large and statistically significant group differences were observed across several contextualized, situation-specific measures of strategic and regulatory thinking. The SREP group also exhibited a statistically significant and more positive trend in achievement scores over two years in middle school relative to the comparison condition. Finally, SREP students and coaches reported SREP to be a socially-valid intervention, in terms of acceptability and importance. The importance of this study and critical areas for future research are highlighted and discussed.

Microanalytic Assessment of Self-Regulated Learning During Clinical Reasoning Tasks: Recent Developments and Next Steps.

Helping medical educators obtain and use assessment data to assist medical students, residents, and physicians in reducing diagnostic errors and other forms of ineffective clinical practice is of critical importance. Self-Regulated Learning-Microanalytic Assessment and Training is an assessment-to-intervention framework designed to address this need by generating data about trainees' strategic processes (e.g., focusing on clinical task procedures), regulatory processes (e.g., planning how to do a task), and motivational processes (e.g., increasing confidence for performing a task) as they perform clinical activities. In this article, the authors review several studies that have used an innovative assessment approach, called self-regulated learning (SRL) microanalysis, to generate data about how trainees regulate their thinking and actions during clinical reasoning tasks. Across the studies, initial findings revealed that medical students often do not exhibit strategic thinking and action during clinical reasoning practice tasks even though some regulatory processes (e.g., planning) are predictive of important medical education outcomes. Further, trainees' motivation beliefs, strategic thinking, and self-evaluative judgments tend to shift rapidly during clinical skills practice and may also vary across different parts of a patient encounter. Collectively, these findings underscore the value of dynamically assessing trainees' SRL as they complete clinical tasks. The findings also set the stage for exploring how medical educators can best use SRL microanalytic assessment data to guide remedial practices and the provision of feedback to trainees. Implications and future research directions for connecting assessments to intervention in medical education are discussed.

Carbapenem-Resistant Acinetobacter baumannii: Concomitant Contamination of Air and Environmental Surfaces.

OBJECTIVE To concomitantly determine the differential degrees of air and environmental contamination by Acinetobacter baumannii based on anatomic source of colonization and type of ICU layout (single-occupancy vs open layout). DESIGN Longitudinal prospective surveillance study of air and environmental surfaces in patient rooms. SETTING A 1,500-bed public teaching hospital in Miami, Florida. PATIENTS Consecutive A. baumannii-colonized patients admitted to our ICUs between October 2013 and February 2014. METHODS Air and environmental surfaces of the rooms of A. baumannii-colonized patients were sampled daily for up to 10 days. Pulsed-field gel electrophoresis (PFGE) was used to type and match the matching air, environmental, and clinical A. baumannii isolates. RESULTS A total of 25 A. baumannii-colonized patients were identified during the study period; 17 were colonized in the respiratory tract and 8 were colonized in the rectum. In rooms with rectally colonized patients, 38.3% of air samples were positive for A. baumannii; in rooms of patients with respiratory colonization, 13.1% of air samples were positive (P=.0001). In rooms with rectally colonized patients, 15.5% of environmental samples were positive for A. baumannii; in rooms of patients with respiratory colonization, 9.5% of environmental samples were positive (P=.02). The rates of air contamination in the open-layout and single-occupancy ICUs were 17.9% and 21.8%, respectively (P=.5). Environmental surfaces were positive in 9.5% of instances in open-layout ICUs versus 13.4% in single-occupancy ICUs (P=.09). CONCLUSIONS Air and environmental surface contaminations were significantly greater among rectally colonized patients; however, ICU layout did not influence the rate of contamination. Infect Control Hosp Epidemiol 2016;37:777-781.

Contamination of Ambient Air with Acinetobacter baumannii on Consecutive Inpatient Days.

Acinetobacter-positive patients had their ambient air tested for up to 10 consecutive days. The air was Acinetobacter positive for an average of 21% of the days; the rate of contamination was higher among patients colonized in the rectum than in the airways (relative risk [RR], 2.35; P = 0.006). Of the 6 air/clinical isolate pairs available, 4 pairs were closely related according to rep-PCR results.

Examining shifts in medical students' microanalytic motivation beliefs and regulatory processes during a diagnostic reasoning task.

This study examined within-group shifts in the motivation beliefs and regulatory processes of second-year medical students as they engaged in a diagnostic reasoning activity. Using a contextualized assessment methodology called self-regulated learning microanalysis, the authors found that the 71 medical student participants showed statistically significant and relatively robust declines in their self-efficacy beliefs and strategic regulatory processes following negative feedback about their performance on the diagnostic reasoning task. Descriptive statistics revealed that changes in strategic thinking following negative corrective feedback were most characterized by shifts away from task-specific processes (e.g., integration, differentiating diagnoses) to non-task related factors. Implications and areas for future research are presented and discussed.

Examining parents' ratings of middle-school students' academic self-regulation using principal axis factoring analysis.

This study examined the reliability and validity of a parent rating scale, the Self-Regulation Strategy Inventory: Parent Rating Scale (SRSI-PRS), using a sample of 451 parents of sixth- and seventh-grade middle-school students. Principal axis factoring (PAF) analysis revealed a 3-factor structure for the 23-item SRSI-PRS: (a) Managing Behavior and Learning (α = .92), (b) Maladaptive Regulatory Behaviors (α = .76), and (c) Managing Environment (α = .84). The majority of the observed relations between these 3 subscales, and the SRSI-SR, student motivation beliefs, and student mathematics grades were statistically significant and in the small to medium range. After controlling for various student variables and motivation indices of parental involvement, 2 SRSI-PRS factors (Managing Behavior and Learning, Maladaptive Regulatory Behaviors) reliably predicted students' achievement in their mathematics course. This study provides initial support for the validity and reliability of the SRSI-PRS and underscores the advantages of obtaining parental ratings of students' SRL behaviors.

Differential environmental contamination with Acinetobacter baumannii based on the anatomic source of colonization.

BACKGROUND: Acinetobacter baumannii is a pathogen of importance worldwide. METHODS: From January 2011 until January 2012, environmental and surveillance cultures were collected from patients admitted to our intensive care units (ICUs). Surveillance cultures were obtained on admission to the ICU and weekly thereafter. Environmental cultures of high-touch surfaces were performed on an alternating basis every week. A room was designated as contaminated if at least 1 object was positive for carbapenem-resistant A baumannii. We only evaluated the rooms belonging to patients who tested positive for Acinetobacter infection. RESULTS: Five hundred eighty-six rooms were cultured across the 5 ICUs surveyed, of which 134 (22.9%) had patients who tested positive for infection with Acinetobacter. Among patients colonized in the rectum, the odds of having bed rails contaminated with A baumannii were 2.55 times the odds of those with only respiratory colonization (P = .03). The odds of having intravenous pumps contaminated with A baumannii among patients with only respiratory colonization were 2.72 times the odds of contamination among patients colonized in the rectum (P = .03). CONCLUSIONS: There was a significant difference in the degree of contamination of bedrails and intravenous pumps based on the occupant's anatomic source of A baumannii infection.

Control of a two-decade endemic situation with carbapenem-resistant Acinetobacter baumannii: electronic dissemination of a bundle of interventions.

BACKGROUND: Our institution continued to experience a hyperendemic situation with carbapenem-resistant Acinetobacter baumannii despite a bundle of interventions. We aim to describe the effect of the subsequent implementation of electronic dissemination of the weekly findings of a bundle of interventions. METHODS: This was a quasiexperimental study performed at a 1,500-bed, public, teaching hospital. From January 2011 to March 2012, weekly electronic communications were sent to the hospital leadership and intensive care units (ICUs). These communications aimed to describe, interpret, and package the findings of the previous week's active surveillance cultures, environmental cultures, environmental disinfection, and hand cultures. Additionally, action plans based on these findings were shared with recipients. RESULTS: During 42 months and 1,103,900 patient-days, we detected 438 new acquisitions of carbapenem-resistant A baumannii. Hospital wide, the rate of acquisition decreased from 5.13 ± 0.39 to 1.93 ± 0.23 per 10,000 patient-days, during the baseline and postintervention periods, respectively (P < .0001). This effect was also observed in the medical and trauma ICUs, with decreased rates from 67.15 ± 10.56 to 17.4 ± 4.6 (P < .0001) and from 55.9 ± 8.95 to 14.71 ± 4.45 (P = .0004), respectively. CONCLUSION: Weekly and systematic dissemination of the findings of a bundle of interventions was successful in decreasing the rates of carbapenem-resistant A baumannii across a large public hospital.

Environmental exposure to carbapenem-resistant Acinetobacter baumannii as a risk factor for patient acquisition of A. baumannii.

We aimed to determine the association between environmental exposure to carbapenem-resistant Acinetobacter baumannii and the subsequent risk of acquiring this organism. Patients exposed to a contaminated hospital environment had 2.77 times the risk of acquiring carbapenem-resistant A. baumannii than did unexposed patients (relative risk, 2.77 [95% confidence interval, 1.50-5.13]; P = .002).

Exploring clinical reasoning in novices: a self-regulated learning microanalytic assessment approach.

OBJECTIVES: The primary objectives of this study were to examine the regulatory processes of medical students as they completed a diagnostic reasoning task and to examine whether the strategic quality of these regulatory processes were related to short-term and longer-term medical education outcomes. METHODS: A self-regulated learning (SRL) microanalytic assessment was administered to 71 second-year medical students while they read a clinical case and worked to formulate the most probable diagnosis. Verbal responses to open-ended questions targeting forethought and performance phase processes of a cyclical model of SRL were recorded verbatim and subsequently coded using a framework from prior research. Descriptive statistics and hierarchical linear regression models were used to examine the relationships between the SRL processes and several outcomes. RESULTS: Most participants (90%) reported focusing on specific diagnostic reasoning strategies during the task (metacognitive monitoring), but only about one-third of students referenced these strategies (e.g. identifying symptoms, integration) in relation to their task goals and plans for completing the task. After accounting for prior undergraduate achievement and verbal reasoning ability, strategic planning explained significant additional variance in course grade (ΔR(2 ) = 0.15, p < 0.01), second-year grade point average (ΔR(2) = 0.14, p < 0.01), United States Medical Licensing Examination Step 1 score (ΔR(2) = 0.08, p < 0.05) and National Board of Medical Examiner subject examination score in internal medicine (ΔR(2) = 0.10, p < 0.05). CONCLUSIONS: These findings suggest that most students in the formative stages of learning diagnostic reasoning skills are aware of and think about at least one key diagnostic reasoning process or strategy while solving a clinical case, but a substantially smaller percentage set goals or develop plans that incorporate such strategies. Given that students who developed more strategic plans achieved better outcomes, the potential importance of forethought regulatory processes is underscored.

Interactions between anesthesiologists and the environment while providing anesthesia care in the operating room.

We describe 1,132 contacts between anesthesiologists and the operating room. Objects most commonly touched included anesthesia machines and keyboards. Only 13 hand hygiene events were witnessed during 8 hours of observations. Line insertions, bronchoscopies, or blood exposures were not followed by hand hygiene. Stopcocks were accessed 66 times and only disinfected on 10 (15%) of these occasions.

Eighteen years of experience with Acinetobacter baumannii in a tertiary care hospital.

OBJECTIVE: To characterize the descriptive and molecular epidemiology of Acinetobacter baumannii in our hospital. DESIGN: Longitudinal analysis of electronic microbiology laboratory records and isolates. SETTING: A 1,500 bed public teaching hospital in the Miami area. PATIENTS: Consecutive patients with A. baumannii from January 1994 to December 2011. INTERVENTIONS: None MEASUREMENTS AND MAIN RESULTS: : Data on all A. baumannii isolates were clustered at the patient level, and the first isolate per single patient was determined. Yearly trends were analyzed based on carbapenem susceptibilities and originating units for all first isolates and first blood isolates per unique patient. Additionally, carbapenem nonsusceptible isolates frozen in the microbiology laboratory since 1998 were retrieved and evaluated using polymerase chain reaction and randomly amplified polymorphic DNA techniques. A total of 9,334 A. baumannii isolates were detected, of which 4,484 isolates (48%) were identified as first positive isolates per unique patient. Most of the burden of disease was located in the ICUs (odds ratio, 2.64 [95% CI, 2.17-3.22]; p < 0.0001) and in the adult wards (odds ratio, 3.867 [95% CI, 2.71-5.52]; p < 0.0001). Respiratory specimens constituted the most frequent source (49%; odds ratio, 1.619 [95% CI, 1.391-1.884]; p < 0.0001). Of the 4,484 first isolates, 846 isolates (18.9%) were carbapenem nonsusceptible and 3,638 isolates (81.1%) were carbapenem susceptible. Over the years, the number of carbapenem nonsusceptible isolates increased, whereas the number of carbapenem susceptible decreased (p < 0.0001). The trauma ICU had the highest burden of carbapenem nonsusceptible first isolates (205 of 846; 24.2%). Seven clones were discovered among 144 carbapenem nonsusceptible isolates; one of these clones was found from 1999 to 2005. OXA-23 and OXA-40 were identified in 96 and 13 isolates, respectively. One isolate harbored a novel CTX-M-115 enzyme. CONCLUSIONS: This constitutes the largest experience with A. baumannii reported to date from a single center. Half of all isolates were respiratory specimens and were from adult ICUs, especially trauma. Even though this was a polyclonal process, a single clone was identified in the hospital through a 6-year span.

Aerosolization of Acinetobacter baumannii in a trauma ICU*.

OBJECTIVE: To establish the presence of air contamination with Acinetobacter baumannii in the trauma ICU. DESIGN: Point prevalence microbiological surveillances. SETTINGS: A 1,500-bed public teaching hospital in the Miami metro area. PATIENTS: Trauma ICU patients. MEASUREMENTS: Pulsed field electrophoresis was performed on environmental and clinical isolates to determine the association of any isolates from the air with clinical isolates. MAIN RESULTS: Out of 53 patient areas cultured, 12 (22.6%) had their air positive for A. baumannii. The presence of an A. baumannii-positive patient (underneath the plate) was associated with positive air cultures for A. baumannii (11 of 21 [52.4%] vs 0 of 25 [0%]; p < 0.0001). However, we were not able to find differences in air contamination based on the presence of A. baumannii in respiratory secretions versus absence (p = 1.0). Air and clinical isolates were found to be clonally related. CONCLUSIONS: Aerosolization of A. baumannii in the ICUs is a concern, and its role in the transmission of this organism among patients should be further clarified.

Human-associated methicillin-resistant Staphylococcus aureus from a subtropical recreational marine beach.

Reports of Staphylococcus aureus including methicillin-resistant S. aureus (MRSA) detected in marine environments have occurred since the early 1990 s. This investigation sought to isolate and characterize S. aureus from marine waters and sand at a subtropical recreational beach, with and without bathers present, in order to investigate possible sources and to identify the risks to bathers of exposure to these organisms. During 40 days over 17 months, 1,001 water and 36 intertidal sand samples were collected by either bathers or investigators at a subtropical recreational beach. Methicillin-sensitive S. aureus (MSSA) and MRSA were isolated and identified using selective growth media and an organism-specific molecular marker. Antimicrobial susceptibility, staphylococcal cassette chromosome mec (SCCmec) type, pulsed-field gel electrophoresis (PFGE) pattern, multi-locus sequence type (MLST), and staphylococcal protein A (spa) type were characterized for all MRSA. S. aureus was isolated from 248 (37 %) bather nearby water samples at a concentration range of <2-780 colony forming units per ml, 102 (31 %) ambient water samples at a concentration range of <2-260 colony forming units per ml, and 9 (25 %) sand samples. Within the sand environment, S. aureus was isolated more often from above the intertidal zone than from intermittently wet or inundated sand. A total of 1334 MSSA were isolated from 37 sampling days and 22 MRSA were isolated from ten sampling days. Seventeen of the 22 MRSA were identified by PFGE as the community-associated MRSA USA300. MRSA isolates were all SCCmec type IVa, encompassed five spa types (t008, t064, t622, t688, and t723), two MLST types (ST8 and ST5), and 21 of 22 isolates carried the genes for Panton-Valentine leukocidin. There was a correlation (r = 0.45; p = 0.05) between the daily average number of bathers and S. aureus in the water; however, no association between exposure to S. aureus in these waters and reported illness was found. This report supports the concept that humans are a potential direct source for S. aureus in marine waters.