Propionibacterium acnes is a common colonizer of intravascular catheters Pablo Martı ´n-Rabada ´n*, Paloma Gijo ´n, Luis Alcala ´, Marta Rodrı ´guez-Cre´ixems, Neisa Alvarado, Emilio Bouza Servicio de Microbiologı´a y Enfermedades Infecciosas, Hospital General Universitario Gregorio Maran˜o´n, Calle Doctor Esquerdo 46, 28007 Madrid, Spain Accepted 16 January 2008 Available online 12 March 2008 KEYWORDS Propionibacterium acnes; Anaerobic bacteria; Prosthetic device; Catheter-related infections; Catheter colonization; Prosthetic device infections Summary Propionibacterium spp. are common flora of human skin. Nevertheless, currently recommended culture procedures do not include anaerobic processing with the result that this organism may go undetected on a colonized catheter. To determine the rate of catheter col- onization by Propionibacterium spp., a sample of 1000 vascular catheters was processed by the roll-plate technique and, after conventional aerobic processing, all primary culture plates were reincubated in an anaerobic atmosphere. Propionibacterium acnes was detected in sig- nificant counts in the vascular catheters of 39 patients. This represents 14.7% (95% CI, 12.5e16.9) of all positive catheters. Propionibacterium is the second most frequent genus- colonizing catheter tips after Staphylococcus spp. Methodological shortcomings impair the de- tection and proper adscription of P. acnes as a potential cause of catheter-related infections. ª 2008 The British Infection Society. Published by Elsevier Ltd. All rights reserved. Introduction Microorganisms that commonly colonize the skin are closely associated with catheter colonization (CC) and catheter- related bloodstream infections (CR-BSI). Propionibacterium acnes is among the commonest bacte- ria of normal human skin and sebaceous glands, although it is rarely reported as a cause of intravascular CC or CR-BSI. Although current guidelines for the management of CR-BSI include Propionibacterium spp. as a potential cause, recommended catheter-culture procedures do not include anaerobic processing. 1 Furthermore, the chances of detect- ing Propionibacterium bacteremia are reduced by current trends in blood culture methods, which include automatic detection of growth without terminal subcultures, reduction of incubation times, and elimination of anaerobic bottles. 2e7 Our hypothesis was that the low rate of CC and CR-BSI caused by Propionibacterium spp. reported in the medical literature is a consequence of inappropriate laboratory detection methodology. The objective of the present study was to determine the rate of CC by Propionibacterium spp. in intravascular cath- eter tips submitted for culture in a large general teaching hospital. * Corresponding author. Tel.: þ34 914 265 001; fax: þ34 915 044 906. E-mail address: pmartinra.hgugm@salud.madrid.org (P. Martı ´n-Rabada ´n). 0163-4453/$34 ª 2008 The British Infection Society. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.jinf.2008.01.012 www.elsevierhealth.com/journals/jinf Journal of Infection (2008) 56, 257e260