Increase in methicillin-resistant Staphylococcus aureus acquisition rate and change in pathogen pattern associated with an outbreak of severe acute respiratory syndrome

Background. An outbreak of severe acute respiratory syndrome (SARS) occurred in our 22-bed intensive care unit (ICU; Prince of Wales Hospital, Hong Kong, HKSAR, China) from 12 March to 31 May 2003, when only patients with SARS were admitted. This period was characterized by the upgrading of infection control precautions, which included the wearing of gloves and gowns all the time, an extensive use of steroids, and a change in antibiotic prescribing practices. The pattern of endemic pathogenic organisms, the rates of acquisition of methicillin-resistant Staphylococcus aureus (MRSA), and the rates of ventilator-associated pneumonia (VAP) were compared with those of the pre-SARS and post-SARS periods. Methods. Data on pathogenic isolates were obtained from the microbiology department (Prince of Wales Hospital). Data on MRSA acquisition and VAP rates were collected prospectively. MRSA screening was performed for all ICU patients. A case of MRSA carriage was defined as an instance in which MRSA was recovered from any site in a patient, and cases were classified as imported or ICU-acquired if the first MRSA isolate was recovered within 72 h of ICU admission or after 72 h in the ICU, respectively. Results. During the SARS period in the ICU, there was an increase in the rate of isolation of MRSA and Stenotrophomonas and Candida species but a disappearance of Pseudomonas and Klebsiella species. The MRSA acquisition rate was also increased: it was 3.53% (3.53 cases per 100 admissions) during the pre-SARS period, 25.30% during the SARS period, and 2.21% during the post-SARS period (P < .001). The VAP rate was high, at 36.5 episodes per 1000 ventilator-days, and 47% of episodes were caused by MRSA. Conclusions. A SARS outbreak in the ICU led to changes in the pathogen pattern and the MRSA acquisition rate. The data suggest that MRSA cross-transmission may be increased if gloves and gowns are worn all the time.published_or_final_versio

Effects of a therapeutic laser on the ultrastructural morphology of repairing medial collateral ligament in a rat model

Background and Objectives: Low energy laser therapy has been shown to enhance mechanical strength of healing medial collateral ligament (MCL) in rats. The present study investigated its effects on the ultrastructural morphology and collagen fibril profile of healing MCL in rats. Study Design/Materials and Methods: Thirty-two mature male Sprague-Dawley (SD) rats were used. Twenty-four underwent surgical transection to their right MCLs and eight received only skin wound. Immediately after surgery, eight of the MCL transected rats were treated with a single dose of laser therapy at 63.2 J cm-2, eight were treated with a single dose of laser therapy at 31.6 J cm-2, the rest had no treatment and served as control. At 3 and 6 weeks after surgery, the MCLs were harvested and examined with electron microscopy for collagen fibril size, distribution, and alignment. Results: Significant differences (P < 0.001) were found in fibril diameters from the same anatomical site and time period among different groups. The mass-averaged diameters of the laser-treated (64.99-186.29 nm) and sham (64.74-204.34 nm) groups were larger than the control group (58.66-85.89 nm). The collagen fibrils occupied 42.55-59.78, 42.63-53.94, and 36.92-71:64% of the total cross-sectional areas in the laser-treated, control and sham groups, respectively. Mode obliquity was 0.53-0.84 among the three groups. Conclusions: Single application of low energy laser therapy increases the collagen fibril size of healing MCLs in rats. © 2003 Wiley-Liss, Inc.link_to_subscribed_fulltex

Therapeutic low energy laser improves the mechanical strength of repairing medial collateral ligament

Background and Objectives: Low energy laser therapy has been shown to enhance collagen production but its effect on tissue strength is not well reported. We tested the effects of therapeutic laser on the strength of healing medial collateral ligaments (MCLs) in rats. Study Design/Materials and Methods: Twenty-four rats received surgical transection to their right MCL and eight received sham operation. After surgery, 16 received a single dose of gallium aluminum arsenide laser to their transected MCL for 7.5 minutes (n = 8) or 15 minutes (n = 8) and eight served as control with placebo laser, while the sham group didn't receive any treatment. The MCLs were biomechanically tested at either 3 or 6 weeks post-operation. Results: The normalized ultimate tensile strength (UTS) and stiffness of laser and sham groups were larger than control (P < 0.001). The UTS of laser and sham groups were comparable. Laser and sham groups had improved in stiffness from 3 to 6 weeks (P < 0.001). Conclusions: A single dose of low energy laser therapy improves the UTS and stiffness of repairing MCL at 3 and 6 weeks after injury. © 2002 Wiley-Liss, Inc.link_to_subscribed_fulltex

Investigation of the collagen fibril distribution in the medial collateral ligament in a rat knee model

This study compared the collagen fibril diameter distribution among six anatomical sites of the rat medial collateral ligament (MCL). Ultrathin MCL sections from 4 male Sparague-Dawley rats were examined electron microscopically. With an automated quantitation method, 41,638 fibrils were measured and compared among the periphery and core regions of the femoral, middle, and tibial portions of the MCL. Results demonstrated significant difference (p < .0033) in mean fibril diameter distribution among the six sites. The mass-averaged diameters of the core and peripheral fibrils were between 175.53 to 190.82 nm and 88.47 to 109.18 nm, respectively, with the peripheral fibrils more homogeneous in size. The fibrils occupied 36.7% to 57.1% of the cross-sectional area of the ligament. About 50% of the fibrils had an oblique factor of 0.8-1.0, implying that most fibrils were aligned longitudinally. This study has provided a detailed profile of the collagen fibril distributions in rat MCL.link_to_subscribed_fulltex

Avaliação imediata da dor e edema em lesão muscular induzida por formalina e tratada com laser 808 nm Immediate pain and edema assessment in muscular injury induced by formalin and treated with low-level laser (808nm)

O laser de baixa potência induz a bioestimulação celular, podendo acelerar a cicatrização de feridas, promover a regeneração do músculo esquelético, diminuir a resposta inflamatória, estimular a neoformação de vasos sanguíneos e diminuir a dor. O objetivo deste estudo foi analisar os efeitos de três doses de laser de baixa intensidade (808nm), na dor e edema imediatos, em ratos submetidos a lesão experimental do músculo gastrocnêmio lateral. Foram utilizados 24 ratos Wistar, distribuídos aleatoriamente em quatro grupos, sendo: GC - animais lesionados e tratados com aparelho desligado (simulacro); G20 - animais lesionados e irradiados com dose de 20J/cm²; G50 - animais lesionados e irradiados com 50J/cm; e G100 - animais lesionados e irradiados com 100J/cm². Para a produção da lesão experimental, introduziu-se 0,1mL de formalina a 5% no ventre do músculo gastrocnêmio lateral direito. A avaliação da dor ocorreu através do tempo de elevação da pata (TEP) e o edema foi avaliado com auxílio de paquímetro metálico; ambas as avaliações ocorreram pré-lesão, pós-lesão, pós-tratamento, duas, oito e 24 horas pós-lesão. Os resultados mostraram aumento significativo do TEP e da avaliação com paquímetro, após a indução da lesão. Conclui-se que laser nos parâmetros utilizados não produziu diminuição na dor e edema, em animais submetidos a lesão muscular com injeção de formalina a 5%.<br>Low-level laser therapy induces to cellular bioestimulation and can accelerate wound healing, promote skeletal muscle regeneration, decrease inflammatory response, stimulate neovascularization and decrease pain. The aim of this study was to analyze the effects of three doses of low-level laser therapy (808 nm), in the immediate pain and edema, in rats submitted to experimental injury of the lateral gastrocnemius muscle. Twenty four Wistar rats, randomly distributed in the following four groups were used: CG - injured and treated with equipment turned off (sham); G20 - injured and treated with 20 J/cm²; G50 - injured and treated with 50 J/cm²; and G100 - injured and treated with 100 J/cm². For the experimental injury production, 0.1 mL of formalin 5% was introduced in the right lateral gastrocnemius muscle girth. Pain was assessed through the Paw Elevation Time (PET), and edema was assessed with a metallic caliper. Both evaluations happened before injury, after injury, after treatment, 2, 8 and 24 hours after injury. The results showed significant increase of PET and of the caliper evaluation after injury induction. It has been concluded that the laser irradiation in the used parameters did not produce pain and edema decrease in rats submitted to muscular injury with formalin 5% injection