Infected wound model development of an in vitro biomaterial-protected wound infection model to study microbial activity and antimicrobial treatment through microdialysis.

OBJECTIVE: Skin injuries provide a favorable environment for microbial infection if left untreated. This is problematic especially in nosocomial situations having a high prevalence of Staphylococcus aureus that can cause suppuration of wounds, systemic disease, and toxic shock. The objective of this investigation was to use a wound model system to study the interactions between microbial activity, host tissue, therapeutic treatments, and wound biomaterials. DESIGN: An in vitro wound model was developed using Sykes-Moore chambers filled with 1 of 2 biomaterials used for wound treatment (1% alginate and dialyzed HyFil hydrogel (B. Braun Medical, Inc, Bethlehem, Pennsylvania) and seeded with fibroblasts. The chambers were inoculated with S aureus, and half were later treated with antibiotics through in situ microdialysis tubing. MAIN OUTCOME MEASURES: The chambers were monitored by obtaining fluid samples and biomaterial samples at specific time intervals (0, 2, 8, and 24 hours) and were analyzed for (1) S aureus protein A (SPA) concentration, (2) viable S aureus numbers, and (3) fibroblast numbers and viability. Chambers containing each biomaterial with and without antibiotics were compared to controls. MAIN RESULTS: There was an inverse relationship between postinfection S aureus numbers and fibroblast viability. S aureus numbers were usually consistent with SPA concentration, which may have been underestimated because of SPA interactions with the biomaterials. CONCLUSION: This wound model may be useful to gain an understanding about the interactions between microbial activity, host tissue, therapeutic treatments, and wound biomaterials. Hypotheses about wound treatments derived by means of this model may direct future in vivo studies.

Assay for 5' noncoding region analysis of all human rhinovirus prototype strains.

Increasing recognition of the association of rhinovirus with severe lower respiratory tract illnesses has clarified the need to understand the relationship between specific serotypes of rhinovirus and their clinical consequences. To accomplish this, a specific and sensitive assay to detect and serotype rhinovirus directly from clinical specimens is needed. Traditional methods of serotyping using culture and serum neutralization are time-consuming, limited to certain reference laboratories, and complicated by the existence of over 100 serotypes of human rhinoviruses (HRVs). Accordingly, we have developed a sequence-based assay that targets a 390-bp fragment accounting for approximately two-thirds of the 5' noncoding region (NCR). Our goal was to develop an assay permitting amplification of target sequences directly from clinical specimens and distinction among all 101 prototype strains of rhinoviruses. We determined the sequences of all 101 prototype strains of HRV in this region to enable differentiation of virus genotypes in both viral isolates and clinical specimens. We evaluated this assay in a total of 101 clinical viral isolates and 24 clinical specimens and compared our findings to genotyping results using a different region of the HRV genome (the VP4-VP2 region). Five specimens associated with severe respiratory disease in children did not correlate with any known serotype of rhinovirus and were found to belong to a novel genogroup of rhinovirus, genogroup C. Isolates were also found that corresponded to the genogroup A2 variant identified in New York and Australia and two other novel group A clusters (GAC1 and GAC2).

Use of personal digital assistants (PDAs) in reflection on learning and practice.

INTRODUCTION: As the use of personal digital assistants (PDAs) grows, the value of reflection of learning and practice draws increased attention from policymakers and evaluators. To learn more about the use of PDAs in practice and learning, the present study describes use of (1) PDAs in patient care and (2) a PDA version of the Virginia Board of Medicine Continuing Competency and Assessment Form (CCAF), a learning portfolio intended to encourage documentation of reflection on practice and medical education. METHODS: A purposive sample of 10 practicing physicians (6 male, 7 primary care) was recruited from geographic regions throughout Virginia. Five participants were previous users of a PDA. Three sources of data were analyzed: (1) a questionnaire describing PDA usage, (2) transcripts from telephone interviews, and (3) CCAF written comments. A study team member installed the PDA system and conducted individualized training on the basis of current equipment, software, and skills of the learner. Telephone interviews were completed 4-6 months after training. RESULTS: All physicians accessed the system after training. Use of the PDA was associated with the value of information for making clinical decisions. Information accessed by PDA was used not only for clinical decisions but also for patient education and for teaching medical students. Use of the CCAF prompted physicians to reflect on changes in clinical practice. DISCUSSION: Training on the handheld equipment and applications should include assessment of systems connectivity and integration, access authority, existing skills, and previous use. Proponents of PDA use for clinical decisions should assure access to information that is useful to physicians for reflection on learning and practice.

Co-detection of Bartonella henselae, Borrelia burgdorferi, and Anaplasma phagocytophilum in Ixodes pacificus ticks from California, USA.

Presence of Bartonella DNA was explored in 168 questing adult Ixodes pacificus ticks from Santa Cruz County, California. Bartonella henselae type I DNA was amplified from 11 ticks (6.55%); previously, two (1.19%) were found to be infected with Borrelia burgdorferi and five (2.98%) with Anaplasma phagocytophilum. Detection of B. henselae was not dependent on co-infection. The present study offers additional evidence that Ixodes spp. ticks may act as hosts and possibly vectors for B. henselae.

Detection of Borrelia burgdorferi, Ehrlichia chaffeensis, and Anaplasma phagocytophilum in ticks (Acari: Ixodidae) from a coastal region of California.

A study was conducted in Santa Cruz County to estimate the prevalence and distribution of the agents of Lyme disease, human granulocytic (HGE), and human monocytic (HME) ehrlichiosis in 1,187 adult ixodid ticks collected from eight public-use recreation areas over a 2-yr period. Borrelia burgdorferi, the causative agent of Lyme disease, was detected by a polymerase chain reaction (PCR) in 44 of 776 (5.67%) Ixodes pacificus ticks and in 3 of 58 (5.17%) Dermacentor variabilis ticks. Anaplasma phagocytophilum, the causative agent of HGE, was detected by PCR in 48 (6.19%) I. pacificus ticks and 5 (8.62%) D. variabilis ticks. Ehrlichia chaffeensis, the causative agent of HME, was detected by nested PCR in just five (0.64%) I. pacificus ticks and four (6.9%) D. variabilis ticks. Interestingly, eight (1.03%) I. pacificus ticks were co-infected with B. burgdorferi and A. phagocytophilum, and just one (0.12%) tick was co-infected with B. burgdorferi and E. chaffeensis. Less than 1% of 353 Dermacentor occidentalis ticks showed evidence of infection with any of the agents tested. To our knowledge, this is the first reported identification of A. phagocytophilum and E. chaffeensis in D. occidentalis ticks from California This study represents the first extensive survey of Lyme and the ehrlichial diseases across multiple areas of Santa Cruz County, and suggests that prevalence of B. burgdorferi in Santa Cruz County may be higher than other areas of the state.

Teaching phagocytosis using flow cytometry.

Investigative microbiology on protists in a basic teaching laboratory environment is limited by student skill level, ease of microbial culture and manipulation, instrumentation, and time. The flow cytometer is gaining use as a mainstream instrument in research and clinical laboratories, but has had minimal application in teaching laboratories. Although the cost of a flow cytometer is currently prohibitive for many microbiology teaching environments and the number of trained instructors and teaching materials is limited, in many ways the flow cytometer is an ideal instrument for teaching basic microbiology. We report here on a laboratory module to study phagocytosis in Tetrahymena sp. using flow cytometry in a basic microbiology teaching laboratory. Students and instructors found the flow cytometry data analysis program, Paint-AGate(PRO-TM), to be very intuitive and easy to learn within a short period of time. Assessment of student learning about Tetrahymena sp., phagocytosis, flow cytometry, and investigative microbiology using an inquiry-based format demonstrated an overall positive response from students.