- Email: [email protected]
Comment on the Effect of Aspirin on Adherence of Slime–Producing, Coagulase-Negative Staphylococci to Vascular Grafts
Vol. 26, No. 3, April 2012
2. Georgakarakos E, Ioannou CV, Volanis S, et al. The influence of intraluminal thrombus on abdominal aortic aneurysm wall stress. Int Angiol 2009;28:325e33. 3. Wang DH, Makaroun MS, Webster MW, Vorp DA. Effect of intraluminal thrombus on wall stress in patient-specific models of abdominal aortic aneurysm. J Vasc Surg 2002;36:598e604. 4. Xu XY, Borghi A, Nchimi A, et al. High levels of 18F-FDG uptake in aortic aneurysm wall are associated with high wall stress. Eur J Vasc Endovasc Surg 2010;39:295e301. 5. Wiernicki I, Stachowska E, Safranow K, et al. Enhanced matrix-degrading proteolytic activity within the thin thrombus-covered wall of human abdominal aortic aneurysms. Atherosclerosis 2010;212:161e5.
DOI: 10.1016/j.avsg.2011.04.013
Comment on the Effect of Aspirin on Adherence of SlimeeProducing, Coagulase-Negative Staphylococci to Vascular Grafts
To the Editor: In their study, Demirag and colleagues1 have reported that salicylic acid at a concentration of 5 mM can inhibit biofilm formation of coagulase-negative staphylococci, represented by the standard strain Staphylococcus epidermidis ATCC 12228, on medical biomaterials, such as Dacron (Dacron Boston Scientific Medi-Tech, Watertown, MA) and polytetrafluoroethylene ([PTFE] W. L. Gore, Flagstaff, AZ). The method used consisted in vortexing a 24-hourincubated sample in medium supplemented or not with salicylic acid, followed by performing colony counts of plated cells on blood agar after an incubation of 24 hours. There is a major concern regarding this study: the standard strain used is not appropriate for such experiments, as S. epidermidis ATCC 12228, known to be a nonpathogenic strain, is not a biofilm (slime) producer strain because it lacks the ica operon, which is the genetic support of enzymes involved in polysaccharide intercellular adhesin synthesis.2 S. epidermidis RP62A (ATCC 35984), a strain isolated from medical implanteassociated infection,3 was the standard strain used to establish the effect of salicylic acid on S. epidermidis biofilm in a previous study.4 Such studies are very important in terms of resolving a major nosocomial infection, but it can give better results with described recommendations. Mohamed Amine Mekni Wafa Achour Assia Ben Hassen, PhD Centre National de Greffe de Moelle Osseuse Bab Saadoun, Tunis, Tunisia E-mail: [email protected] REFERENCES 1. Demirag MK, Esen S, Zivalioglu M, et al. The effect of aspirin on adherence of slime-producing, coagulase-negative staphylococci to vascular grafts. Ann Vasc Surg 2007;21:464e7.
Letters to the Editor 445
2. Holden M, Crossman L, Cerde~ no-Tarraga A, Parkhill J. Pathogenomics of non-pathogens. Nat Rev Microbiol 2004;2:91. 3. Christensen GD, Barker LP, Mawhinney TP, et al. Identification of an antigenic marker of slime production for Staphylococcus epidermidis. Infect Immun 1990;58:2906e11. 4. Muller E, Al-Attar J, Wolff AG, Farbe BF. Mechanism of salicylate-mediated inhibition of biofilm in Staphylococcus epidermidis. J Infect Dis 1998;177:501e3.
DOI: 10.1016/j.avsg.2011.04.014
Ultrasound Assessment of Morphological and Functional Vessel Parameters Should Be a Mandatory Step Before Arteriovenous Fistula Placement
To the Editor: We have read with great interest the article on improved wrist arteriovenous fistula (AVF) outcome by Kim et al.,1 who reported that the radiocephalic vein diameter increased by >0.35 mm on venography, using tourniquet method. They also accentuated that ‘‘ideally, venography results should be compared with those of Doppler scanning.’’ We truly agree with this statement and would like to share our opinion concerning vein distensibility (VD) as an important functional parameter in the prediction of early outcomes of AVF. First, Malovrh2 reported a better primary patency rate for wrist AVF in patients whose internal vein diameter, measured using ultrasound (US) technique, after proximal vein compression increased by 48%, compared with 11.8% in patients with primary AVF failure (P < 0.01). The author also found a high correlation between US measurement of internal vein diameter and direct measurement during surgery (r ¼ 0.69, P < 0.01). Second, US as a noninvasive, easily reproducible, safe, and cost-effective method could be used not only in vessel diameter measurements (which are certainly most important factors in AVF outcome prediction, although reported cutoff values are inconsistent) but also in the measurement of the ability of the vein to dilate after proximal vein compression as a functional parameter. Another advantage of US over phlebography and angiography is that contrast agents are not needed, and thus there is no risk for allergic reactions, phlebitis, and deterioration of residual renal function. Our preliminary results on 114 patients regarding the role of vascular functional parameters that influenced the success of primary AVF for hemodialysis were presented in November 2011 at the ASN Kidney meeting in Philadelphia.3 We showed VD as the most important factor influencing primary AVF patency rates after 4 weeks of maturation. Significant correlation was found between AVF outcome and VD (P ¼ 0.017); also, linear regression was significant for VD (B ¼ 0.517, 95% confidence interval: 0.054e0.981, P ¼ 0.029).
2. Georgakarakos E, Ioannou CV, Volanis S, et al. The influence of intraluminal thrombus on abdominal aortic aneurysm wall stress. Int Angiol 2009;28:325e33. 3. Wang DH, Makaroun MS, Webster MW, Vorp DA. Effect of intraluminal thrombus on wall stress in patient-specific models of abdominal aortic aneurysm. J Vasc Surg 2002;36:598e604. 4. Xu XY, Borghi A, Nchimi A, et al. High levels of 18F-FDG uptake in aortic aneurysm wall are associated with high wall stress. Eur J Vasc Endovasc Surg 2010;39:295e301. 5. Wiernicki I, Stachowska E, Safranow K, et al. Enhanced matrix-degrading proteolytic activity within the thin thrombus-covered wall of human abdominal aortic aneurysms. Atherosclerosis 2010;212:161e5.
DOI: 10.1016/j.avsg.2011.04.013
Comment on the Effect of Aspirin on Adherence of SlimeeProducing, Coagulase-Negative Staphylococci to Vascular Grafts
To the Editor: In their study, Demirag and colleagues1 have reported that salicylic acid at a concentration of 5 mM can inhibit biofilm formation of coagulase-negative staphylococci, represented by the standard strain Staphylococcus epidermidis ATCC 12228, on medical biomaterials, such as Dacron (Dacron Boston Scientific Medi-Tech, Watertown, MA) and polytetrafluoroethylene ([PTFE] W. L. Gore, Flagstaff, AZ). The method used consisted in vortexing a 24-hourincubated sample in medium supplemented or not with salicylic acid, followed by performing colony counts of plated cells on blood agar after an incubation of 24 hours. There is a major concern regarding this study: the standard strain used is not appropriate for such experiments, as S. epidermidis ATCC 12228, known to be a nonpathogenic strain, is not a biofilm (slime) producer strain because it lacks the ica operon, which is the genetic support of enzymes involved in polysaccharide intercellular adhesin synthesis.2 S. epidermidis RP62A (ATCC 35984), a strain isolated from medical implanteassociated infection,3 was the standard strain used to establish the effect of salicylic acid on S. epidermidis biofilm in a previous study.4 Such studies are very important in terms of resolving a major nosocomial infection, but it can give better results with described recommendations. Mohamed Amine Mekni Wafa Achour Assia Ben Hassen, PhD Centre National de Greffe de Moelle Osseuse Bab Saadoun, Tunis, Tunisia E-mail: [email protected] REFERENCES 1. Demirag MK, Esen S, Zivalioglu M, et al. The effect of aspirin on adherence of slime-producing, coagulase-negative staphylococci to vascular grafts. Ann Vasc Surg 2007;21:464e7.
Letters to the Editor 445
2. Holden M, Crossman L, Cerde~ no-Tarraga A, Parkhill J. Pathogenomics of non-pathogens. Nat Rev Microbiol 2004;2:91. 3. Christensen GD, Barker LP, Mawhinney TP, et al. Identification of an antigenic marker of slime production for Staphylococcus epidermidis. Infect Immun 1990;58:2906e11. 4. Muller E, Al-Attar J, Wolff AG, Farbe BF. Mechanism of salicylate-mediated inhibition of biofilm in Staphylococcus epidermidis. J Infect Dis 1998;177:501e3.
DOI: 10.1016/j.avsg.2011.04.014
Ultrasound Assessment of Morphological and Functional Vessel Parameters Should Be a Mandatory Step Before Arteriovenous Fistula Placement
To the Editor: We have read with great interest the article on improved wrist arteriovenous fistula (AVF) outcome by Kim et al.,1 who reported that the radiocephalic vein diameter increased by >0.35 mm on venography, using tourniquet method. They also accentuated that ‘‘ideally, venography results should be compared with those of Doppler scanning.’’ We truly agree with this statement and would like to share our opinion concerning vein distensibility (VD) as an important functional parameter in the prediction of early outcomes of AVF. First, Malovrh2 reported a better primary patency rate for wrist AVF in patients whose internal vein diameter, measured using ultrasound (US) technique, after proximal vein compression increased by 48%, compared with 11.8% in patients with primary AVF failure (P < 0.01). The author also found a high correlation between US measurement of internal vein diameter and direct measurement during surgery (r ¼ 0.69, P < 0.01). Second, US as a noninvasive, easily reproducible, safe, and cost-effective method could be used not only in vessel diameter measurements (which are certainly most important factors in AVF outcome prediction, although reported cutoff values are inconsistent) but also in the measurement of the ability of the vein to dilate after proximal vein compression as a functional parameter. Another advantage of US over phlebography and angiography is that contrast agents are not needed, and thus there is no risk for allergic reactions, phlebitis, and deterioration of residual renal function. Our preliminary results on 114 patients regarding the role of vascular functional parameters that influenced the success of primary AVF for hemodialysis were presented in November 2011 at the ASN Kidney meeting in Philadelphia.3 We showed VD as the most important factor influencing primary AVF patency rates after 4 weeks of maturation. Significant correlation was found between AVF outcome and VD (P ¼ 0.017); also, linear regression was significant for VD (B ¼ 0.517, 95% confidence interval: 0.054e0.981, P ¼ 0.029).