Microbiology Division, Department of Laboratory Medicine and Pathology, Hamad Medical Corporation, Doha, Qatar;
Department of Pediatric, Hamad Medical Corporation, Doha, Qatar;
Can J Infect Dis Med Microbiol. 2013 Summer;24(2):e33-8. doi: 10.1155/2013/256025.
Nocardia species are rare, opportunistic organisms that cause disease in both immunocompetent and immunocompromised individuals.
To investigate the clinical presentations of various Nocardia infections based on the 16S ribosomal RNA gene of the isolate, as well as related risk factors and susceptibility patterns to antimicrobial agents.
Thirteen patients with a diagnosis of nocardiosis were included in the present study. Seven Nocardia species were identified by 16S ribosomal RNA. Susceptibility testing was performed using six antimicrobial agents.
Five patients were immunocompromised, and eight were immunocompetent with predisposing factors including cystic fibrosis, tuberculosis and ophthalmic infections. Nocardia caused pulmonary infections in eight patients (61.5%), invasive systemic infections in three patients (23%) and local (ophthalmic) infections in two patients (15.4%). In the patients with pulmonary disease, nocardiosis was caused by six species (Nocardia cyriacigeorgica, Nocardia otitidiscaviarum, Nocardia farcinica, Nocardia carnea, Nocardia testacea and Nocardia asiatica). The seventh species identified in the present study was Nocardia crassostreae.
N crassostreae is a multidrug-resistant organism that was reported to be an emerging human pathogen causing invasive nocardiosis in a patient with non-Hodgkin's lymphoma. N farcinica was isolated from blood in a patient with breast cancer. None of the Nocardia isolates were resistant to linezolid. One N otitidiscaviarum isolate was a multidrug-resistant organism. All patients in the present study were treated with the appropriate antibiotics and their condition resolved without further sequelae.
The present study is the first report on N crassostreae as a human pathogen. The detection of multidrug-resistant species necessitate molecular identification and susceptibility testing, and should be performed for all Nocardia infections. Nocardiosis manifests various clinical features depending on the Nocardia species and underlying conditions.
奴卡氏菌属是一种罕见的机会致病菌，可引起免疫功能正常和免疫功能低下个体的疾病。
根据分离株的 16S 核糖体 RNA 基因，以及相关的危险因素和对抗菌药物的敏感性模式，研究各种奴卡氏菌感染的临床表现。
本研究纳入了 13 例诊断为奴卡氏菌病的患者。通过 16S 核糖体 RNA 鉴定出 7 种奴卡氏菌。采用 6 种抗菌药物进行药敏试验。
5 例患者免疫功能低下，8 例免疫功能正常但存在易感因素，包括囊性纤维化、肺结核和眼部感染。奴卡氏菌引起 8 例患者肺部感染（61.5%）、3 例侵袭性系统性感染（23%）和 2 例局部（眼部）感染（15.4%）。患有肺部疾病的患者中，奴卡氏菌由 6 种（触须奴卡氏菌、耳炎奴卡氏菌、星形奴卡氏菌、肉色奴卡氏菌、 testa 奴卡氏菌和亚洲奴卡氏菌）引起。本研究中鉴定的第 7 种为海扇贝奴卡氏菌。
海扇贝奴卡氏菌是一种多药耐药菌，被报道为一种新兴的人类病原体，可引起非霍奇金淋巴瘤患者侵袭性奴卡氏菌病。星形奴卡氏菌从乳腺癌患者的血液中分离出来。没有奴卡氏菌分离株对利奈唑胺耐药。1 株耳炎奴卡氏菌分离株为多药耐药菌。本研究中的所有患者均接受了适当的抗生素治疗，病情得到缓解，无进一步的后遗症。
本研究首次报道海扇贝奴卡氏菌为人类病原体。检测到多药耐药菌需要进行分子鉴定和药敏试验，所有奴卡氏菌感染均应进行此项检测。奴卡氏菌病的临床表现因奴卡氏菌种类和基础疾病而异。
