Nephron injury induced by diagnostic ultrasound imaging at high mechanical index with gas body contrast agent

The right kidney of anesthetized rats was imaged with intermittent diagnostic ultrasound (1.5 MHz; 1-s trigger interval) under exposure conditions simulating those encountered in human perfusion imaging. The rats were infused intravenously with 10 microL/kg/min Definity (Bristol-Myers Squibb Medical Imaging, Inc., N. Billerica, MA, USA) while being exposed to mechanical index (MI) values of up to 1.5 for 1 min. Suprathreshold MI values ruptured glomerular capillaries, resulting in blood filling Bowman's space and proximal convoluted tubules of many nephrons. The re-establishment of a pressure gradient after hemostasis caused the uninjured portions of the glomerular capillaries to resume the production of urinary filtrate, which washed some or all of the erythrocytes out of Bowman's space and cleared blood cells from some nephrons into urine within six hours. However, many of the injured nephrons remained plugged with tightly packed red cell casts 24 h after imaging and also showed degeneration of tubular epithelium, indicative of acute tubular necrosis. The additional damage caused by the extravasated blood amplified that caused by the original cavitating gas body. Human nephrons are virtually identical to those of the rat and so it is probable that similar glomerular capillary rupture followed by transient blockage and/or epithelial degeneration will occur after clinical exposures using similar high MI intermittent imaging with gas body contrast agents. The detection of blood in postimaging urine samples using standard hematuria tests would confirm whether or not clinical protocols need to be developed to avoid this potential for iatrogenic injury.     

Studying sex and gender differences in pain and analgesia: a consensus report

In September 2006, members of the Sex, Gender and Pain Special Interest Group of the International Association for the Study of Pain met to discuss the following: (1) what is known about sex and gender differences in pain and analgesia; (2) what are the "best practice" guidelines for pain research with respect to sex and gender; and (3) what are the crucial questions to address in the near future? The resulting consensus presented herein includes input from basic science, clinical and psychosocial pain researchers, as well as from recognized experts in sexual differentiation and reproductive endocrinology. We intend this document to serve as a utilitarian and thought-provoking guide for future research on sex and gender differences in pain and analgesia, both for those currently working in this field as well as those still wondering, "Do I really need to study females?"     

Spanish-language version of the MedRisk Instrument for Measuring Patient Satisfaction With Physical Therapy Care (MRPS): preliminary validation

BACKGROUND AND PURPOSE: An instrument that provides valid measurements of satisfaction with physical therapy care for Spanish-speaking patients will enhance communication and ensure their representation in quality assurance analyses and research on health care disparities. The purpose of this investigation was to provide preliminary information on the factor structure, group- and individual-level reliability, and criterion-referenced validity of measurements obtained from a Spanish-language version of the MedRisk Instrument for Measuring Patient Satisfaction With Physical Therapy Care (MRPS). SUBJECTS: A total of 203 Spanish-speaking patients in the New York City area participated in this study. METHODS: Consenting subjects completed a 20-item MRPS after discharge from outpatient physical therapy care. Several translators performed "forward" and "backward" translation of the MRPS, followed by consensus agreement on item structure. Factor structure was investigated using item-correlation and exploratory factor analysis. Group-level reliability for single test administration was assessed using the Cronbach alpha, and individual-level reliability was assessed by calculating the standard error of the measure (SEM). Concurrent validity was tested by comparing the item scores and mean scores of factors to global measures of satisfaction. RESULTS: The means of individual item scores (1-5) ranged from 3.22 for "I did not wait too long" to 4.80 for "My therapist treated me respectfully." There were no sex-based differences in item scores. Exploratory factor analysis suggested a 2-factor solution: a 7-item "external" factor and a 3-item "internal" factor. The correlations (r) of the mean scores from these factors with the 2 global measures ranged from .59 to .82. The SEM was 0.16 for the internal factor and 0.25 for the external factor. DISCUSSION AND CONCLUSION: The underlying factor structure of the Spanish-language version of the MRPS was identical to the English-language version. Our findings provide preliminary support for the reliability and validity of measurements obtained from the Spanish-language version of the MRPS. Further study is needed to assess the stability of these findings in other samples. As with English-speaking patients, Spanish-speaking patient's satisfaction with physical therapy care is most strongly linked to the professional behavior of the clinician.     

Activity of colistin against heteroresistant Acinetobacter baumannii and emergence of resistance in an in vitro pharmacokinetic/pharmacodynamic model

Three clinically relevant intermittent regimens, and a continuous infusion, of colistin were simulated in an in vitro pharmacokinetic/pharmacodynamic model against two colistin-heteroresistant strains of Acinetobacter baumannii. Extensive initial killing was followed by regrowth as early as 6 h later; bacterial density in the 24- to 72-h period was within 1 log(10) CFU/ml of growth control. Population analysis profiles revealed extensive emergence of resistant subpopulations regardless of the colistin regimen.     

Antibiotics for the eradication of Propionibacterium acnes biofilms in surgical infection

OBJECTIVES: Propionibacterium acnes is increasingly recognized as a cause of delayed infection after spinal instrumentation or shunting for hydrocephalus. Biofilm development by this organism has recently been demonstrated. We therefore investigated the effect of two different courses of three antibiotics (penicillin, rifampicin and linezolid) on mature P. acnes biofilms in vitro. Outcomes were eradication or regrowth after withdrawal of antibiotics, simulating successful treatment and relapse. METHODS: P. acnes biofilms were grown on titanium discs for 6 days until mature, then exposed to the antibiotics for either 7 or 14 days before sonication and culture. Further, discs were similarly exposed, but after each course, they were reincubated for a further 9 days to check for regrowth. RESULTS: Penicillin, linezolid and linezolid plus rifampicin eradicated P. acnes biofilms after 14 days, but only penicillin had this effect after 7 days. 'Relapse' was prevented only by 14 day courses of penicillin or linezolid plus rifampicin, but not by linezolid alone. CONCLUSIONS: For P. acnes spinal instrumentation infections, either penicillin or linezolid plus rifampicin might be equally effective. For shunt infections, as penicillin does not give therapeutic cerebrospinal fluid concentrations, rifampicin plus linezolid might be the treatment of choice. Linezolid alone appears not to be as effective as penicillin against P. acnes biofilms.     

Triclosan resistance in methicillin-resistant Staphylococcus aureus expressed as small colony variants: a novel mode of evasion of susceptibility to antiseptics

OBJECTIVES: Triclosan is in widespread use in domestic, commercial and healthcare settings and is used to reduce methicillin-resistant Staphylococcus aureus (MRSA) load in carriers. Triclosan resistance is uncommon, usually being due to mutation in fabI or overexpression of efflux pumps. This study investigated the ability of triclosan-containing silicone elastomer to kill MRSA adherent to its surface. METHODS: Silicone discs containing triclosan were prepared by a matrix-expansion method previously described. Discs were exposed to three strains of MRSA for 1 h for adhesion to take place. After incubation, discs were removed at intervals, sonicated and the sonicates analysed by chemiluminescence and viable counting. Survivors were found to consist of small colony variants (SCVs). These were then subjected to tests for known SCV characteristics and for susceptibility to triclosan. RESULTS: Viable counts fell until 51 h, when they began to increase, due to SCV. Of the three SCV strains, two showed impaired coagulase production and all showed reduced deoxyribonuclease production. None was auxotrophic. MICs of triclosan in the SCV rose by between 8- and 67-fold. CONCLUSIONS: Prolonged exposure of MRSA to triclosan-impregnated silicone, as in 'antimicrobial' plastics or catheters, resulted in the induction of SCV status and triclosan resistance. This has implications for industrial, medical and domestic use of polymers containing triclosan. SCVs are pathogenic and persistent. The widespread use of triclosan could lead to infection with MRSA SCVs, and new antimicrobials with physiological targets similar to that of triclosan might give rise to SCV resistance in clinical use.