International Journal of Antimicrobial Agents 38 (2011) 534–537 Contents lists available at SciVerse ScienceDirect International Journal of Antimicrobial Agents j our na l ho me p age: http://www.elsevier.com/locate/ijantimicag Short communication Clinical characteristics of infections caused by Tsukamurella spp. and antimicrobial susceptibilities of the isolates Chia-Ying Liu a,1 , Chih-Cheng Lai b,1 , Meng-Rui Lee c , Yi-Chieh Lee c , Yu-Tsung Huang a,c,d , Chun-Hsing Liao a , Po-Ren Hsueh c,d,∗ a Department of Internal Medicine, Far Eastern Memorial Hospital, New Taipei City, Taiwan b Department of Intensive Care Medicine, Chi-Mei Medical Center, Liouying, Tainan, Taiwan c Department of Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan d Department of Laboratory Medicine, National Taiwan University Hospital, National Taiwan University College of Medicine, Taipei, Taiwan a r t i c l e i n f o Article history: Received 12 June 2011 Accepted 29 July 2011 Keywords: Tsukamurella Rhodococcus Keratitis Catheter-related bacteraemia a b s t r a c t To investigate the clinical and microbiological characteristics of infections caused by Tsukamurella spp., the computerised database of the Bacteriology Laboratory at National Taiwan University Hospital (Taipei, Taiwan) was reviewed retrospectively to identify patients with infections caused by this species dur- ing the period January 1997 to December 2008. All of the isolates had been initially misidentified as Rhodococcus spp. Identification of Tsukamurella isolates to species level was carried out by polymerase chain reaction–restriction fragment length polymorphism (PCR-RFLP) analysis of the heat shock protein gene (hsp65) as well as 16S rRNA gene sequencing. During the study period, a total of eight patients with Tsukamurella infection and two patients with Tsukamurella colonisation were identified. Tsuka- murella tyrosinosolvens (n = 6) was the most prevalent species, followed by Tsukamurella spumae (n = 3) and Tsukamurella pulmonis (n = 1). Keratitis was the most common type of infection (n = 3), followed by catheter-related bloodstream infection (n = 2). One of the patients with Tsukamurella infection died due to bacteraemia; the other seven patients with Tsukamurella infection had favourable outcomes. The three species had different drug susceptibility patterns; T. pulmonis was the most resistant pathogen, with higher minimum inhibitory concentrations of clindamycin (>2 mg/L), erythromycin (2 mg/L) and tetracycline (8 mg/L) than those for the other Tsukamurella spp. In conclusion, strains of Tsukamurella spp., including T. spumae, are uncommon causative agents of ocular infections and bacteraemia in cancer patients. Molecular diagnostic methods are essential to distinguish species in the Tsukamurella genus from species in other phylogenetically related genera such as Rhodococcus. © 2011 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved. 1. Introduction Tsukamurella spp. are Gram-positive, weakly acid-fast bacilli belonging to the aerobic Actinomycete family [1]. Species in the Tsukamurella genus share many features with species in other genera such as Rhodococcus, Corynebacterium, Nocardia and Mycobacterium [2]. Therefore, advanced molecular methods such as polymerase chain reaction–restriction fragment length polymor- phism (PCR-RFLP) for the heat shock protein gene (hsp65) as well as 16S rRNA gene sequencing analysis are needed to distinguish between species in the Tsukamurella genus from species in other phylogenetically related genera [2–4]. ∗ Corresponding author. Tel.: +886 2 2312 3456x5355; fax: +886 2 2322 4263. E-mail address: hsporen@ntu.edu.tw (P.-R. Hsueh). 1 These two authors contributed equally to this work. Human infections caused by Tsukamurella spp. are rare; the most common presentation is catheter-related bloodstream infection (CR-BSI) [3–7]. Other less common infections include peritonitis due continuous ambulatory peritoneal dialysis [8], respiratory tract infection [9], skin and soft-tissue infections [10], brain abscess [11] and ocular infections [12,13]. A better understanding of the clinical and microbiological manifestations of infections caused by Tsuka- murella spp. is needed. In the present study, we describe two cases of Tsukamurella spp. colonisation and eight cases of various types of infection caused by Tsukamurella spp. All of the isolates had been initially misidentified as Rhodococcus spp. 2. Materials and methods 2.1. Hospital setting and patient selection This study was conducted at National Taiwan University Hos- pital (NTUH), a 2500-bed tertiary-care centre in northern Taiwan. 0924-8579/$ – see front matter © 2011 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved. doi:10.1016/j.ijantimicag.2011.07.018