广东省一例白喉疑似病例的病原学检测和流行病学调查

Etiologic detection and epidemiological analysis of one suspected case of diphtheria in Guangdong province

目的对广东省发现的1例疑似白喉病例进行流行病学调查和病原学检测，以明确诊断。方法2010年7月6日，广东省广州市大学城某医院在1例鼻咽癌患者的鼻腔分泌物中检出白喉棒状杆菌。对患者及其密切接触者进行流行病学调查，采集患者及其密切接触者咽拭子标本（3份）和患者鼻腔分泌物标本（1份），采用血平板和吕氏斜面进行细菌分离培养，对阳性菌株进行细菌涂片染色鉴定；应用梅里埃APICoryne棒状杆菌生化鉴定昔进行生化鉴定；应用PCR方法测定白喉棒状杆菌B棒状杆菌噬菌体tox基因；应用气相色谱法进行脂肪酸分析；采用白喉棒状杆菌（重型，编号：CMCC38009）作为阳性对照。结果患者近1个多月无外出史及来访史，否认疫苗接种史。对患者的家人及5名密切接触者进行调查，未发现有类似症状的病例。从患者鼻腔分泌物中分离到1株白喉棒状杆菌，革兰染色阳性，形态多样化，经吕氏斜面培养后进行革兰染色和奈瑟染色，菌体一端或两端见特征性的异染颗粒，APICoryne生化鉴定提示99．4％是缓和白喉棒状杆菌。用气相色谱法进行脂肪酸分析，结果显示为白喉棒状杆菌。患者及其密切接触者咽拭子均未分离到白喉棒状杆菌。PCR检测白喉棒状杆菌β棒状杆菌噬菌体tox基因，结果为阴性。结论此次分离到的白喉棒状杆菌菌株不带有毒素生物结构基因，为非毒源菌株，该病例为无毒白喉棒状杆菌健康带菌者。

Objective To clarify the diagnosis of one suspected case of diphtheria in Guangdong province by epidemiological analysis and etiologic detection. Methods On July 6th 2010, the corynebacterium diphtheria was detected from the nasal secretions of one nasopharyngeal carcinoma patient in a college-town hospital in Guangzhou City, Guangdong Province. The patient and the close contacts were asked to participate in the epidemiological survey; and their nasopharyngeal swabs （3 samples） and the nasal secretions of the patient （ 1sample ） were collected. The bacteria of the samples were isolated and cultured by bloodplate and agar loefflera. The smears of positive strains were dyed and identified by BioMerieux API Coryne biochemical card. Gene tox of β-Corynebacteriophage, Corynebacterium diphtheriae was tested by PCR method, the aliphatic acid was analyzed by gas chromatography method and the Corynebacterium diphtheriae （CMCC 38009 ） was selected as positive control. Results The patient had not gone out, neither had been visited. The patient denied history of vaccines or the immunizations. From the survey on patient＇s family members and close contacts, no similar symptoms had been found. One strain of Corynebacterium diphtheriae was isolated from the patient＇s nasal secretions, Gram positive and shape diversified. After cultured by agar loefflera and Gram-dyed and Neisser-dyed, one end or both two ends of the strain showed typical metachromatic granule. API Coryne was identified to Corynebacterium diphtheriae mitis/belfanti （99.4%）. The result of gas chromatography method also indicated Corynebacteriumdiphtheriae. No Corynebacterium diphtheriae was isolated from the nasopharyngeal swabs, neither of the patient nor of the close contacts. The gene tox of β-Corynebacteriophage, Corynebacterium diphtheriae was negative according to the PCR test. Conclusion The isolated Corynebacterium diphtheriae did not produce toxin as there was no biological structure gene of toxin. The patient was a health carrier of nontoxic Corynebacterium diphtheriae.