Aerobic actinomycetes that masquerade as pulmonary tuberculosis

Background: There is an increasing recognition of organisms in the order Actinomycetales including Nocardia sp. causing lung infections that mimic pulmonary tuberculosis or fungal pneumonias. Methods: We retrospectively evaluated a cohort of patients in the southeastern United States in whom a presumptive diagnosis of pulmonary tuberculosis was initially entertained but who eventually were found to have infection caused by Rhodococcus sp. or Tsukamurella sp. Results: Among a cohort of 52 individuals diagnosed as case suspects for pulmonary tuberculosis, we identified six patients who were infected with either Rhodococcus sp. or Tsukamurella sp. Of these six patients, two had co-infection with Mycobacterium tuberculosis. Conclusions: Infection with aerobic actinomycetes may mimic pulmonary tuberculosis or may cause concomitant disease in patients with pulmonary tuberculosis.

A Case of Catheter-Related Bloodstream Infection by Tsukamurella inchonensis in a Pediatric Patient Receiving Home Intravenous Antibiotic Treatment

Bacteria belonging to the genus Tsukamurella are aerobic, gram-positive rods that are weakly acid-fast with no apparent branching. Infections of the Tsukamurella spp. are generally caused by the use of infected medical devices such as central venous catheters. The underreporting of these infections might be attributable to the frequent misdiagnosis of Tsukamurella infections as Corynebacterium or atypical Mycobacterium spp. infections. Therefore, when gram-positive aerobic rods are observed in the blood culture of a patient with a central venous catheter, it is important to consider Tsukamurella as one of the causative organisms. Here, we report the first case of a catheter-related blood stream infection caused by Tsukamurella inchonensis in a 3-yr-old Korean girl with underlying biliary atresia who underwent hepatoportoenterostomy.

A Case Report of Tsukamurella pulmonis Infection Misidentified as Atypical Mycobacteria / 대한임상미생물학회지

We report a case of catheter-related bacteremia due to Tsukamurella pulmonis. T. pulmonis is a rare cause of opportunistic infection in immunosuppressed patients and in cases of indwelling foreign materials. This infection was nearly impossible to identify using conventional phenotyping methods because of its similarities to the related genera Nocardia, Rhodococcus, Gordonia, Streptomyces, Corynebacterium, and Mycobacterium. This organism was initially misidentified as Mycobacterium aubagnense through PCR-RFLP analysis. We correctly identified this organism using 16S rRNA sequencing combined with phenotyping tests.

A case of Tsukamurella tyrosinosolvens peritonitis associated with continuous ambulatory peritoneal dialysis / 대한내과학회지

A case of Tsukamurella peritonitis associated with continuous ambulatory peritoneal dialysis (CAPD) in a 54-year-old woman is described. Peritonitis is a common complication of peritoneal dialysis in patients with end-stage renal disease. Tsukamurella has been reported to cause rare opportunistic infections in humans, and most cases have been reported in immunocompromised patients or patients with indwelling foreign bodies. This organism is difficult to identify and has been mistaken for Corynebacterium and atypical Mycobacteria. Here, we describe the first case of CAPD-related peritonitis caused by Tsukamurella tyrosinosolvens in Korea. It was treated with CAPD catheter removal.

A Case of Catheter-Related Bacteremia of Tsukamurella pulmonis / 대한진단검사의학회지

Tsukamurella pulmonis is an aerobic actinomycete. We report a catheter-related bacteremia of T. pulmonis. A 39 yr-old male with ALL was hospitalized to receive bone marrow transplantation (BMT). Although the patient developed a high fever at the 7th hospital day (HD), it subsided with vancomycin treatment, and he received BMT at 9th HD. Fever resurged at 16th HD despite sustained treatment with vancomycin, meropenem, and amphotericin B, but subsided with removal of Hickman catheter (HC) at 19th HD. Three sets of blood cultures comprising one from the HC and two from venipunctures were taken at 7th, 16th, and 19th HD, and the distal tip of the HC was also cultured. The aerobic vials of all 3 HC-withdrawn blood cultures and one peripheral blood culture taken at 19HD and the HC tip culture grew long, straight, thin gram-positive rods that were positive on modified Kinyoun stain. This organism showed tiny, rough, grey colonies after 3-day incubation and grew to large flat colonies when incubation was extended. It was catalase-positive, urease-positive, and alkaline-slant/alkaline-deep on triple sugar iron agar, and hydrolyzed hypoxanthine. The sequence of 1,296 base pairs of 16S rRNA of this organism showed a 100.0% homology with the published sequence of T. pulmonis DSM 44142T. To our knowledge, this is the first report of T. pulmonis bacteremia in Korea.