The Use of a Multimodal Case Study To Illustrate Microbial Genetics, Metabolism, and Evolution: The Emergence of VRSA-1.

Antibiotic Resistance (ABR) is a global concern and while many students are aware of this issue, many of them are unclear on the mechanisms by which ABR may emerge. The mechanism of horizontal gene transfer is something many students are not familiar with. In this curriculum contribution we present 2 versions of an 'interrupted case study' that is designed as an introduction to horizontal gene transfer for early major students and as a review case for advanced major students in biology and life sciences. The case is based on an authentic patient who developed infections with both methicillin resistant Staphylococcus aureus and vancomycin resistant S. aureus. The interrupted case study is appropriate for small and large groups and engages students while content is introduced in a highly structured way. This type of case study can be done by novice and seasoned instructors and lead to considerable learning gains in both introductory and intermediate microbiology courses.

Minimizing the risk of recutting with a Hansatome over an existing Automated Corneal Shaper flap for hyperopic laser in situ keratomileusis enhancement.

We report a case series of 4 eyes to discuss the intraoperative complications of recutting a laser in situ keratomileusis (LASIK) flap with a Hansatome microkeratome over an existing 160 microm Automated Corneal Shaper flap for the retreatment of hyperopia. In the eyes that were recut, slivers of stroma were apparent on reflection of the flap; the slivers were located centrally in the 180 microm eye and peripherally in the 160 microm eyes. Recutting a flap for LASIK retreatment runs the risk of visually significant stromal irregularities.

Late traumatic flap dislocation after laser in situ keratomileusis.

Three patients who had laser in situ keratomileusis (LASIK) experienced severe direct corneal trauma 3 to 38 months postoperatively. Flap dislocation resulted in all 3 patients. Presentation following trauma ranged from a few hours to 9 days. All patients were successfully managed by surgical flap repositioning, and all maintained a best corrected visual acuity of 20/20. A literature review of traumatic flap dislocation cases and the most recent methods of diagnosis and management are included.

Diffuse lamellar keratitis: isolation of endotoxin and demonstration of the inflammatory potential in a rabbit laser in situ keratomileusis model.

PURPOSE: To systematically examine sources of endotoxin contamination in eye centers as a potential cause of diffuse lamellar keratitis (DLK) and to demonstrate the inflammatory potential of endotoxin in a rabbit model of laser in situ keratomileusis (LASIK) surgery. SETTING: University of Calgary, Calgary, Alberta, Canada. METHODS: In this prospective study, all water sources that routinely come in contact with LASIK instruments, including sterilizer reservoirs, eyedrops, microkeratome blades, and cleaning solutions, were examined for endotoxins at 5 eye centers. Bacterial cultures were performed on water samples from 5 sterilizer reservoirs. A LASIK flap was created in 8 rabbit eyes using an Automated Corneal Shaper microkeratome (Bausch & Lomb). The flaps were reflected, and a dose of endotoxin at various concentrations was placed on the interface. After 1 minute, the flap was irrigated and repositioned. The rabbit eyes were examined daily with a slitlamp biomicroscope for 3 days for the development of DLK, which was classified on a scale from grade 1 to 4 (mild to severe). The rabbits were killed at the conclusion of the study, and the interfaces were stained to rule out infectious etiologies. RESULTS: Endotoxin was detected in significant concentrations in tap water, filtered and distilled water, instrument washbasins, and sterilizer reservoirs at all 5 centers. The cultures of the water samples taken from the sterilizer reservoirs ranged from no growth to the presence of >100 colony-forming units of Flavobacterium and Pseudomonas aeruginosa. Endotoxins caused DLK-like interface inflammation in all eyes tested. Examination of stained scrapings showed no microorganisms in the interface of the rabbit eyes. CONCLUSION: Endotoxin contamination was detected in water sources that routinely come in contact with LASIK instruments. Endotoxins were capable of inducing interface inflammation in a rabbit model and may therefore be a significant factor in epidemic DLK.

Accuracy of Orbscan pachymetry measurements and DHG ultrasound pachymetry in primary laser in situ keratomileusis and LASIK enhancement procedures.

PURPOSE: To assess the accuracy and variability in pachymetry measurements obtained by Orbscan and by DGH ultrasound in primary laser in situ keratomileusis (LASIK) and LASIK enhancement procedures. SETTING: Gimbel Eye Centre, Calgary, Alberta, Canada. METHODS: A retrospective analysis of 906 consecutive primary LASIK and 183 consecutive LASIK enhancement procedures for which preoperative DGH ultrasound and Orbscan pachymetry measurements were obtained. The theoretical residual corneal thickness was compared to measurements by both instruments in 60 eyes that had primary procedures and enhancements. RESULTS: In primary LASIK eyes, the DGH ultrasound measurements were thicker than the Orbscan measurements by a mean of 18.4 microm +/- 17.4 (SD). The DGH ultrasound measurements were thicker than the Orbscan measurements by a mean of 50.1 +/- 40.7 microm in preenhancement pachymetry measurements. The DGH ultrasound measurements were consistent with theoretical residual corneal thickness, 493.0 +/- 42.0 microm versus 487.0 +/- 31.0 microm (P =.65), while Orbscan measurements were statistically less than the theoretical residual corneal thickness, 431.0 +/- 42.0 microm versus 468.0 +/- 39.0 microm (P =.0001). CONCLUSION: DGH ultrasound was a more accurate measurement of corneal pachymetry than Orbscan. The discrepancies between DGH ultrasound and Orbscan pachymetry measurements were more prominent in eyes that had had LASIK.

A low temperature transfer of ALH84001 from Mars to Earth.

The ejection of material from Mars is thought to be caused by large impacts that would heat much of the ejecta to high temperatures. Images of the magnetic field of martian meteorite ALH84001 reveal a spatially heterogeneous pattern of magnetization associated with fractures and rock fragments. Heating the meteorite to 40 degrees C reduces the intensity of some magnetic features, indicating that the interior of the rock has not been above this temperature since before its ejection from the surface of Mars. Because this temperature cannot sterilize most bacteria or eukarya, these data support the hypothesis that meteorites could transfer life between planets in the solar system.

Laser in situ keratomileusis to correct residual myopia and astigmatism after radial keratotomy.

PURPOSE: To evaluate the safety and efficacy of laser in situ keratomileusis (LASIK) in selected post-radial-keratotomy (RK) eyes with residual myopia and astigmatism. SETTING: TLC-The Brea Laser Eye Center, Brea, California, USA. METHODS: Nine eyes of 6 patients who had had RK but had residual myopia and/or astigmatism had LASIK. All RK eyes had 8 radial incisions, were more than 1 year post-RK, had no epithelial inclusion cysts or corneal disease, and had had no subsequent ocular surgery. Follow-up was a minimum of 13 months, at which time uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), manifest refraction, cycloplegic refraction, keratometry, central and peripheral pachymetries, intraocular pressure, and a subjective assessment of visual function were obtained. RESULTS: At the last follow-up, the mean spherical equivalent (SE) was -0.156 diopter (D) +/- 0.174 (SD). All eyes treated for distance vision had a UCVA of 20/25 or better. No patient lost BCVA. No intraoperative or postoperative complications occurred. Seven eyes had morning and evening measurements. The mean change in manifest SE from morning to evening was -0.143 D. Six of the 7 eyes (86%) had 0 to 1 Snellen line change in UCVA from morning to evening. The subjective questionnaire revealed a high degree of satisfaction with overall vision, minimal glare, and less fluctuation in daily vision than before LASIK. CONCLUSION: Laser in situ keratomileusis is safe and efficacious for reducing residual myopia and astigmatism in properly selected RK patients.

Postoperative complications in laser in situ keratomileusis.

Laser in situ keratomileusis (LASIK) has become the most common procedure to correct refractive errors in North America. Increasing numbers of patients and surgeons are choosing LASIK in the management of low and moderate myopia, astigmatism, and hyperopia. LASIK presents a unique group of postoperative challenges and complications. It is important to be able to identify these complications in the early and late postoperative periods and to provide effective management. In this article, we review the most commonly encountered early and late postoperative complications after LASIK and the most current methods in prevention and treatment.

Lichenoid dermatitis in paraneoplastic pemphigus: a pathogenic trigger of epitope spreading?

BACKGROUND: In select cases, lichen planus has been observed to be a paraneoplastic condition sometimes associated with paraneoplastic pemphigus, a disease featuring autoantibodies directed against plakin proteins, desmogleins 3 and 1, and a still uncharacterized 170-kd antigen. Epitope spreading describes the phenomenon where underlying chronic inflammation leads to the sequential recognition of new epitopes on self-proteins over time. OBSERVATIONS: Five of 6 patients diagnosed as having paraneoplastic pemphigus had concomitant clinical and histological features of lichen planus. In 1 patient, results of the initial indirect immunofluorescence on rat bladder were negative and only 2 of the 5 antigens were identified by immunoprecipitation. After 1 year of worsening disease, repeated testing confirmed the presence of antibodies directed against all 6 of the implicated antigens, supportive of our hypothesis that epitope spreading may occur in paraneoplastic pemphigus. CONCLUSIONS: Lichenoid eruptions may predispose to an early evolutionary stage of paraneoplastic pemphigus. Cell-mediated autoimmunity at the dermoepidermal junction may promote the exposure of self-antigens and the development of subsequent and progressive humoral autoimmunity. As such, paraneoplastic pemphigus may demonstrate epitope spreading in a human, humoral-mediated autoimmune disease.

Laser in situ Keratomileusis Flap Complications and Management.

PURPOSE: To provide detailed descriptions of intraoperative and postoperative flap complications independent of the microkeratome. Management of these complications is discussed. METHODS: Complications have been assimilated and categorized based on our past experiences and those of others. Methods for managing these complications are discussed. RESULTS: Positive results were considered to be successful resolution of the flap complication, which typically occurs in the majority of cases. CONCLUSION: LASDX is a technically difficult surgical procedure with unique complications. Excellent flap management both intraoperatively and postoperatively is essential to maximize visual outcome. Some flap complications are easily managed and others require immediate expert surgical intervention to preserve good visual outcomes. [J Refract Surg 2000;16(suppl):S223-S225].

Prevention and Management of Microkeratome-related Laser in situ Keratomileusis Complications.

PURPOSE: To review the most commonly encountered laser in situ keratomileusis (LASIK) microkeratome-related complications, and the most up-to-date methods in their prevention and treatment. METHODS: A review of microkeratome-related complications including epithelial complications, bleeding, thin flap, button hole, free cap, incomplete pass, and corneal perforation was conducted. The most recent techniques for prevention and treatment of each complication were included. RESULTS AND CONCLUSION: Microkeratome complications are difficult to predict. With proper attention to anatomical and mechanical considerations, many can be reduced or prevented. [J Refract Surg 2000;16(suppl):S226-S229].

Extensive lower eyelid pigment spread after blepharopigmentation.

PURPOSE: To report on a complication of blepharopigmentation. METHODS: Case report. RESULTS: An 81-year-old woman underwent cosmetic tattooing of all four eyelids. The pigment immediately spread from the right lower eyelid lash line to the nasojugal fold. The dispersion was so extensive in surface area that nonsurgical techniques for ameliorating the dispersion would not be effective. The unintentionally tattooed skin was excised and reconstructed with a lateral canthal suspension and full thickness skin grafts. Pathologic examination of the excised tissue revealed pigmentation of all layers of the skin and the surface of the orbicularis muscle. CONCLUSION: This case illustrates that extensive pigment spread following blepharopigmentation may require extensive reconstruction to correct the problem.

Effect of increased atmospheric pressure on radial keratotomy.

PURPOSE: To evaluate the effect of increased atmospheric pressure on visual acuity in patients who have had radial keratotomy (RK). SETTING: Long Beach Memorial Medical Center, Long Beach, California, USA. METHODS: This controlled clinical study comprised 4 eyes that had RK and 4 control eyes that were age and sex matched. All patients had prehyperbaric chamber examinations consisting of manifest and cycloplegic refractions, intraocular pressure (IOP), keratometry, and corneal pachymetry. They were then placed into the hyperbaric chamber for 1 hour. Immediately after the patients were removed from the chamber, the examinations were performed again. RESULTS: No statistically significant changes in visual acuity, refractive error, IOP, keratometry, or pachymetry occurred in the 2 groups. CONCLUSION: The results of this study indicate that, unlike at high altitudes, RK is stable at increased atmospheric pressure. This suggests that RK patients can engage in recreational scuba diving without encountering deleterious visual changes.

Topical intrastromal steroid during laser in situ keratomileusis to retard interface keratitis.

PURPOSE: To evaluate the effect of an intraoperative topical intrastromal steroid on the incidence and severity of nonspecific diffuse intralamellar keratitis (NSDIK). SETTING: T.L.C. The Laser Center, Brea, California, USA. METHODS: This prospective study included 2 cohort groups, each consisting of 105 consecutive eyes treated with laser in situ keratomileusis (LASIK) for myopia and astigmatism. Group A received the standard LASIK medication protocol and Group B, an additional drop of prednisolone sodium phosphate 1% solution on the undersurface of the cap immediately after it was reflected, prior to initiating the laser treatment. After the laser treatment was completed, the flap was repositioned; 1 minute after the steroid application, the interface was irrigated. All patients were examined postoperatively and placed in 1 of 4 categories: no interface keratitis, grade 1 (mild), grade 2 (moderate with decreased vision), or grade 3 (severe with decreased vision). RESULTS: The incidence of NSDIK in Group A was 17.1% (18 eyes); 14 eyes (78.0%) were grade 1 and 4 (22.0%), grade 2. The incidence in Group B was 6.7% (7 eyes); all eyes were grade 1. Topical intrastromal steroid application significantly reduced the incidence and severity of NSDIK (P < .01). CONCLUSION: We propose that intraoperative intrastromal steroid application is a safe and effective way to reduce the incidence and severity of NSDIK.

A surgical wound infection due to Mycobacterium chelonae successfully treated with clarithromycin.

BACKGROUND: Mycobacterium chelonae is an uncommon but recognized cause of chronic localized cutaneous infection at a site of penetrating trauma or a surgical wound. OBJECTIVE: The problem faced by physicians encountering an infection by M. chelonae is often response to therapy, which may be highly variable. METHODS: We describe an immunocompetent patient who developed a localized infection due to M. chelonae following surgery for a basal cell carcinoma of the lower leg. RESULTS: The infection responded to treatment with clarithromycin. CONCLUSION: The clinical efficacy of clarithromycin and the salient features of M. chelonae infection and its treatment are discussed.