Medical Students' Diagnostic Accuracy and Treatment Plans.

Physician-mentored patient rounds (PMPR) were used to assess diagnostic accuracy and treatment plans of preclinical medical students. During 4 PMPR sessions, students gathered patient history, observed a physical exam, analyzed diagnostic tests, and developed treatment plans for a patient with chronic obstructive pulmonary disease. Of 470 students, 99.4% correctly diagnosed the patient. Nearly 78% prescribed long-acting beta-agonists or long-acting muscarinic antagonists. Most included appropriate pharmacologic treatments. Only 47% included smoking cessation in their treatment.

Detection and partial characterization of extracellular inducers of persistence in Staphylococcus epidermidis and Staphylococcus aureus.

Introduction. This study describes the identification and partial characterization of persistence-inducing factors (PIFs) from staphylococci.Hypothesis/Gap Statement. Increases in persisters during mid-log phase growth indicate that quorum-sensing factors might be produced by staphylococci.Aim. To identify and partially characterize PIFs from Staphylococcus epidermidis RP62A and Staphylococcus aureus SH1000.Methodology. Others have demonstrated a significant increase in persister numbers during mid-log phase. Inducers of this mid-log increase have yet to be identified in staphylococci. Optical density at 600 nm (OD600) was used instead of time to determine when persister numbers increased during logarithmic growth. Concentrated culture filtrates (CCFs) from S. epidermidis and S. aureus were obtained at various OD600s and following incubation at 16 h. The CCFs were used to develop a PIF assay. The PIF assay was used to partially characterize PIF from S. epidermidis and S. aureus for sizing of PIF activity, temperature and protease sensitivity and inter-species communications.Results. The optimal OD600s for S. epidermidis and S. aureus PIF assays were 2.0 and 0.5, respectively. The highest PIF activity for both species was from CCF following incubation overnight (16 h). S. epidermidis' PIF activity was decreased by storage at 4 oC but not at 20 oC (16 h), 37 oC (1 h) or 100 oC (15 min). S. aureus' PIF activity was decreased following storage at 4 oC (2 weeks) and after boiling at 100 oC for 5 min but not after incubation at 37 oC (1 h). PIF activity from both species went through a 3000 molecular weight cutoff ultrafilter. Proteinase K treatment of S. aureus PIF decreased activity but did not decrease the PIF activity of S. epidermidis. PIF from S. epidermidis did not increase persisters when used to treat S. aureus cells and nor did PIF from S. aureus increase persisters when used to treat S. epidermidis cells.Conclusions. Attempts to discover PIFs for staphylococci were unsuccessful due to the time-based means used to identify mid-log. Both staphylococcal species produce extracellular, low-molecular-weight inducers of persistence when assayed using an OD600 -based PIF assay.

Physician-Mentored Patient Rounds to Observe and Assess Entrustable Professional Activities 1 and 2 in Preclinical Medical Students.

CONTEXT: Thirteen entrustable professional activities (EPAs) for entering residency were created to aid medical educators as they prepare preclinical students for their residency and to assess student readiness for residency. The A.T. Still University Kirksville College of Osteopathic Medicine (ATSU-KCOM) developed a program called physician-mentored patient rounds (PMPR), which focuses on EPA 1 and EPA 2. OBJECTIVE: To determine whether PMPRs could be used to assess expected behaviors of EPA 1 (gather a history and perform a physical examination) and EPA 2 (prioritize a differential diagnosis after a clinical encounter). METHODS: The PMPR sessions at ATSU-KCOM take place over several weeks (30-minute sessions per week), during which students gather a patient's history (sessions 1 and 2), observe a physical examination by the physician mentor (session 2), analyze diagnostic test results (session 3), and formulate a treatment plan (session 4). The PMPRs in this study used a real patient with confirmed chronic obstructive pulmonary disease (COPD). This study did not include the session-4 treatment plan. Between sessions, students completed an assignment to further demonstrate their behaviors as expected in the EPAs. Student responses were analyzed and summarized for physician feedback in the subsequent PMPR session. Students' diagnostic accuracy was measured at the conclusion of each session. RESULTS: A total of 516 students were included in the study. The PMPR weekly attendance was high (453-475). Although history gathering in the large-group setting was disorderly, diagnostic accuracy over the 3-session period improved. After history taking, 411 students (86.5%) included COPD in the differential diagnosis. A smaller number, 235 students (49.5%), listed COPD as the most likely diagnosis. After the physical examination, 439 included COPD in the differential diagnosis, and 385 listed COPD as the most likely diagnosis. After analysis of diagnostic test results, 468 students listed COPD as the most likely diagnosis. CONCLUSION: Physician-mentored patient rounds seem to be an effective means to assess preclinical students' expected behaviors as described in EPA 1 and EPA 2.

Effect of clpP and clpC deletion on persister cell number in Staphylococcus aureus.

Staphylococcus aureus is responsible for a wide variety of infections that include superficial skin and soft tissue infections, septicaemia, central nervous system infections, endocarditis, osteomyelitis and pneumonia. Others have demonstrated the importance of toxin-antitoxin (TA) modules in the formation of persisters and the role of the Clp proteolytic system in the regulation of these TA modules. This study was conducted to determine the effect of clpP and clpC deletion on S. aureus persister cell numbers following antibiotic treatment. Deletion of clpP resulted in a significant decrease in persister cells following treatment with oxacillin and erythromycin but not with levofloxacin and daptomycin. Deletion of clpC resulted in a decrease in persister cells following treatment with oxacillin. These differences were dependent on the antibiotic class and the CFU ml-1 in which the cells were treated. Persister revival assays for all the bacterial strains in these studies demonstrated a significant delay in resumption of growth characteristic of persister cells, indicating that the surviving organisms in this study were not likely due to spontaneous antibiotic resistance. Based on our results, ClpP and possibly ClpC play a role in persister cell formation or maintenance, and this effect is dependent on antibiotic class and the CFU ml-1 or the growth phase of the cells.

Utilization of case presentations in medical microbiology to enhance relevance of basic science for medical students.

BACKGROUND: Small-group case presentation exercises (CPs) were created to increase course relevance for medical students taking Medical Microbiology (MM) and Infectious Diseases (ID) METHODS: Each student received a unique paper case and had 10 minutes to review patient history, physical exam data, and laboratory data. Students then had three minutes to orally present their case and defend why they ruled in or out each of the answer choices provided, followed by an additional three minutes to answer questions. RESULTS: Exam scores differed significantly between students who received the traditional lecture-laboratory curriculum (Group I) and students who participated in the CPs (Group II). In MM, median unit exam and final exam scores for Group I students were 84.4% and 77.8%, compared to 86.0% and 82.2% for Group II students (P<0.018; P<0.001; Mann-Whitney Rank Sum Test). Median unit and final ID exam scores for Group I students were 84.0% and 80.0%, compared to 88.0% and 86.7% for Group II students (P<0.001; P<0.001). CONCLUSION: Students felt that the CPs improved their critical thinking and presentation skills and helped to prepare them as future physicians.

Osteopathic medical students' beliefs about osteopathic manipulative treatment at 4 colleges of osteopathic medicine.

CONTEXT: Osteopathic manipulative treatment (OMT) is a distinctive and foundational aspect of osteopathic medicine. Several studies have reported a decline in the use of OMT by practicing osteopathic physicians, but the reasons for this decline have not been fully investigated. OBJECTIVE: To investigate osteopathic medical students' attitudes and beliefs regarding osteopathic philosophy, including OMT. METHODS: A self-administered, 21-item, electronic questionnaire developed specifically for the current study was distributed to first- and second-year osteopathic medical students at 4 colleges of osteopathic medicine. The questionnaire contained items addressing student attitudes toward osteopathic philosophy, including OMT; perceptions of osteopathic predoctoral education; and plans for integrating OMT into future practice. RESULTS: Of 1478 questionnaires sent, 491 students completed the questionnaire for an overall response rate of 33%. Analysis of student responses revealed that a majority of first- and second-year osteopathic medical students (95%-76%, depending on the question asked) expressed agreement with osteopathic philosophy. Students who reported prior exposure to OMT had higher levels of agreement with osteopathic philosophy statements (P<.04) and with the intention to use OMT (P<.02) than students with no prior exposure. However, students who were drawn to an osteopathic medical school by the desire to become a physician regardless of degree reported lower levels of agreement with osteopathic philosophy and the intention to use OMT. Students' levels of agreement with osteopathic philosophy and intention to use OMT varied significantly based on the school that they attended, their current year of study, and whether or not they were participating in clinical rotations. CONCLUSION: The reason why a student decided to study osteopathic medicine was strongly associated with the level of agreement with osteopathic philosophy and the intention to use OMT in future practice. Prior experience receiving OMT, the medical school that a student attends, and the current year of study appear to be related to the students' levels of agreement with osteopathic philosophy and intention to use OMT.

Prevalence of methicillin resistant Staphylococcus aureus in nasal samples from preclinical second-year medical students.

In other studies, around 40% of preclinical medical students were colonized with Staphylococcus aureus but none were MRSA. This study was conducted to determine the level of S. aureus and MRSA in the nares of second year medical students. Over 47% of the student samples contained S. aureus. Five percent of S. aureus isolates possessed the mecA gene. Medical students in this study had a higher percent colonization with S. aureus and MRSA than previous studies.

Evidence for persisters in Staphylococcus epidermidis RP62a planktonic cultures and biofilms.

The pathogenesis of Staphylococcus epidermidis in foreign device-related infections is attributed primarily to its ability to form biofilms on a polymer surface. One mechanism proposed for the survival of organisms in a biofilm is the presence of persister cells. Persister cells survive antibiotic treatment without acquiring heritable antibiotic resistance. This study was conducted to determine if S. epidermidis RP62a growing in planktonic cultures and biofilms could survive as persister cells following treatment with levofloxacin and vancomycin. S. epidermidis RP62a produced a small percentage of persisters (levofloxacin, 3.09×10⁻7%; vancomycin, 8.21×10⁻5 %) when grown to exponential phase, whereas biofilms contained 28 and 94 % persisters, following exposure to levofloxacin and vancomycin, respectively. The highest percentages of persisters were obtained during stationary phase in planktonic cultures and the lowest percentages of persisters were obtained during mid-exponential phase. An increase in persister number was not due to activation of quorum-sensing regulons. Confocal laser scanning microscopy images of biofilms exposed to levofloxacin demonstrated that the antibiotic was able to kill bacteria throughout the biofilm. Our results suggest that antibiotic tolerance in biofilms and in planktonic cultures of S. epidermidis RP62a is due in part to the presence of persister cells.

Insertional inactivation of branched-chain alpha-keto acid dehydrogenase in Staphylococcus aureus leads to decreased branched-chain membrane fatty acid content and increased susceptibility to certain stresses.

Staphylococcus aureus is a major community and nosocomial pathogen. Its ability to withstand multiple stress conditions and quickly develop resistance to antibiotics complicates the control of staphylococcal infections. Adaptation to lower temperatures is a key for the survival of bacterial species outside the host. Branched-chain alpha-keto acid dehydrogenase (BKD) is an enzyme complex that catalyzes the early stages of branched-chain fatty acid (BCFA) production. In this study, BKD was inactivated, resulting in reduced levels of BCFAs in the membrane of S. aureus. Growth of the BKD-inactivated mutant was progressively more impaired than that of wild-type S. aureus with decreasing temperature, to the point that the mutant could not grow at 12 degrees C. The growth of the mutant was markedly stimulated by the inclusion of 2-methylbutyrate in the growth medium at all temperatures tested. 2-Methylbutyrate is a precursor of odd-numbered anteiso fatty acids and bypasses BKD. Interestingly, growth of wild-type S. aureus was also stimulated by including 2-methylbutyrate in the medium, especially at lower temperatures. The anteiso fatty acid content of the BKD-inactivated mutant was restored by the inclusion of 2-methylbutyrate in the medium. Fluorescence polarization measurements indicated that the membrane of the BKD-inactivated mutant was significantly less fluid than that of wild-type S. aureus. Consistent with this result, the mutant showed decreased toluene tolerance that could be increased by the inclusion of 2-methylbutyrate in the medium. The BKD-inactivated mutant was more susceptible to alkaline pH and oxidative stress conditions. Inactivation of the BKD enzyme complex in S. aureus also led to a reduction in adherence of the mutant to eukaryotic cells and its survival in a mouse host. In addition, the mutant offers a tool to study the role of membrane fluidity in the interaction of S. aureus with antimicrobial substances.

Role for dnaK locus in tolerance of multiple stresses in Staphylococcus aureus.

Heat-shock proteins are essential for stress tolerance and allowing organisms to survive conditions that cause protein unfolding. The role of the Staphylococcus aureus DnaK system in tolerance of various stresses was studied by disruption of dnaK by partial deletion and insertion of a kanamycin gene cassette. Deletion of dnaK in S. aureus strain COL resulted in poor growth at temperatures of 37 degrees C and above, and reduced carotenoid production. The mutant strain also exhibited increased susceptibility to oxidative and cell-wall-active antibiotic stress conditions. In addition, the mutant strain had slower rates of autolysis, suggesting a correlation between DnaK and functional expression of staphylococcal autolysins. Deletion of dnaK also resulted in a decrease in the ability of the organism to survive in a mouse host during a systemic infection. In summary, the DnaK system in S. aureus plays a significant role in the survival of S. aureus under various stress conditions.

A prospective study of osteopathic medical students' attitudes toward use of osteopathic manipulative treatment in caring for patients.

Two computer-assisted clinical case SOAP (subjective, objective, assessment, plan) note exercises were used for second-year osteopathic medical students, and a standardized patient was used during third year to measure recording behaviors regarding structural examinations and osteopathic manipulative treatment (OMT). Students were questioned before leaving campus for clinical rotations and at pregraduation to determine their attitudes toward use of these skills. Ninety-one percent of the students recorded structural examination findings in both computer-assisted clinical case SOAP notes, and 61% suggested OMT be given on their basic science SOAP (pneumonia). All of the students in the osteopathic theory and methods exercise suggested OMT. On a standardized patient with chronic obstructive pulmonary disease, 11% of the students performed a structural examination, and 0.7% suggested OMT. Preclinically, 73% of the students believed they were prepared to conduct structural examinations, and 71% believed they were prepared to use OMT. Between 64% and 73% of pregraduation students, however, reported they had few opportunities to use these skills during clinical rotations. Most of the students believed they would use palpatory diagnosis and OMT for fewer than 25% of their future patients and primarily for patients with musculoskeletal problems.