Balıkcı Ahmet, Topkaya Aynur E, Belaş Zeliha
Maltepe University Faculty of Medicine, Department of Medical Microbiology, İstanbul, Turkey.
Mikrobiyol Bul. 2011 Jul;45(3):535-40.
Arcanobacterium haemolyticum, previously known as Corynebacterium haemolyticum, is a facultative anaerobic, gram-positive bacillus with negative catalase and positive CAMP inhibition test results. It may be the causative agent of about 0.5-3% of acute bacterial pharyngitis especially in children and young adults. Since growth of A.haemolyticum is usually inhibited by flora members and since it slowly develops hemolysis in sheep blood agar and its colony morphology resembles beta-hemolytic streptococci, it is frequently overlooked in the evaluation of throat cultures. The aims of this study were to investigate the isolation frequency of A.haemolyticum from the throat cultures of pediatric patients by using both sheep and human blood agar media, and to evaluate the performances of those media for the identification of A.haemolyticum. A total of 355 patients (median age: 7 years) who were admitted to pediatric outpatient clinics with the symptoms of tonsillopharyngitis between March-July 2010 period, were included in the study. Swab samples obtained from tonsils and posterior oropharynx were inoculated into a divided plate which contained 5% sheep blood agar in one half and 5% human blood agar in the other half. After incubation in 5% CO2 at 37°C, the beta-hemolytic colonies with a microscopic morphology of gram-positive bacilli were further evaluated on 24, 48 and 72th hours. Identification of A.haemolyticum was based on negative catalase test, positive reverse CAMP test and biochemical characteristics obtained by API-Coryne (bioMérieux, France) identification system. In our study, beta-hemolytic colonies were detected in the throat cultures of 56 (16%) patients, of which 14% (49/355) were identified as beta-hemolytic streptococci (46 group A, 2 group G, 1 group C), and 2% (7/355) were identified as A.haemolyticum. All of the A.haemolyticum isolates were characterized by the production of beta-hemolysis in human blood agar at 24 hours, while the beta-hemolysis generation time in sheep blood agar was 48 hours for four isolates and 72 hours for three isolates. A.haemolyticum was identified in 2% of children with tonsillopharyngitis during the five months study period in spring/summer. All of the strains were isolated at human blood agar in 24 hours. Thus, in order to isolate A.haemolyticum in routine throat cultures, sheep blood agar plates together with human blood agar plates should be used in clinical microbiology laboratories.
溶血隐秘杆菌，以前称为溶血棒状杆菌，是一种兼性厌氧、革兰氏阳性杆菌，过氧化氢酶试验阴性，CAMP抑制试验阳性。它可能是约0.5%-3%急性细菌性咽炎的病原体，尤其是在儿童和年轻人中。由于溶血隐秘杆菌的生长通常受到菌群成员的抑制，并且它在羊血琼脂中溶血发展缓慢，其菌落形态类似于β-溶血性链球菌，因此在咽喉培养物评估中经常被忽视。本研究的目的是通过使用羊血琼脂和人血琼脂培养基，调查儿科患者咽喉培养物中溶血隐秘杆菌的分离频率，并评估这些培养基对溶血隐秘杆菌的鉴定性能。共有355例患者（中位年龄：7岁）纳入研究，这些患者在2010年3月至7月期间因扁桃体咽炎症状入住儿科门诊。从扁桃体和口咽后部采集的拭子样本接种到一个分隔平板中，平板的一半含有5%羊血琼脂，另一半含有5%人血琼脂。在37°C、5%二氧化碳环境中孵育后，在第24、48和72小时对革兰氏阳性杆菌微观形态的β-溶血菌落进行进一步评估。溶血隐秘杆菌的鉴定基于过氧化氢酶试验阴性、反向CAMP试验阳性以及通过API-棒状杆菌（法国生物梅里埃公司）鉴定系统获得的生化特征。在我们的研究中，56例（16%）患者的咽喉培养物中检测到β-溶血菌落，其中14%（49/355）被鉴定为β-溶血性链球菌（46例A组、2例G组、1例C组），2%（7/355）被鉴定为溶血隐秘杆菌。所有溶血隐秘杆菌分离株的特征是在人血琼脂中24小时产生β-溶血，而在羊血琼脂中，4株分离株的β-溶血产生时间为48小时，3株分离株为72小时。在春季/夏季的五个月研究期间，2%患有扁桃体咽炎的儿童中鉴定出溶血隐秘杆菌。所有菌株均在人血琼脂中24小时分离得到。因此，为了在常规咽喉培养物中分离溶血隐秘杆菌，临床微生物实验室应同时使用羊血琼脂平板和人血琼脂平板。
