[Etiologic detection and epidemiological analysis of one suspected case of diphtheria in Guangdong province].
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 (1 sample) were collected. The bacteria of the samples were isolated and cultured by blood plate 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 Corynebacterium diphtheriae. 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.


CONCLUSIONS
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.
Institute of Microbiology, Center for Disease Control and Prevention of Guangdong Province, Guangzhou 510300, China. gz-lmz@163.com
Mei-zhen
MZ
Liu
Wei-zheng
WZ
Zhang
Jun
J
Shu
Jing-diao
JD
Chen
Da-wei
DW
Guan
Chuan-xi
CX
Fu
Bo
B
Yang
Bi-xia
BX
Ke
Chang-wen
CW
Ke
D002681:China / Q000453:epidemiology; D003353:Corynebacterium diphtheriae / Q000302:isolation & purification*; D004165:Diphtheria / Q000453:epidemiology* / Q000382:microbiology*; D005260:Female; D006801:Humans; D008875:Middle Aged; D009305:Nasopharynx / Q000382:microbiology; D016133:Polymerase Chain Reaction / Q000379:methods