Species-specific DNA probe for the detection of Porphyromonas gingivalis from adult Chinese periodontal patients and healthy subjects.
BACKGROUND
It has been reported that Porphyromonas gingivalis is closely associated with chronic periodontitis and its detection has been recommended as a routine marker for periodontal diagnosis. The purpose of this study was to evaluate the sensitivity and specificity of a DNA probe to detect P. gingivalis in adult Chinese periodontitis patients as well as to find a rapid and convenient method to detect P. gingivalis in clinical practice.


METHODS
A total of 26 bacterial strains (20 reference strains and 6 clinical isolates) were collected, of which 5 were P. gingivalis and 21 were heterologous species. A DNA fragment of 542 bp, which encodes the fimbriae subunit protein (fimA) of P. gingivalis, was obtained by polymerase chain reaction (PCR) and molecular cloning techniques and used to construct the DNA probe, labeled with 32P or with digoxigenin. The constructed DNA probe was used to detect P. gingivalis in specimens collected from the periodontal pockets of 100 patients clinically confirmed with chronic periodontitis. One hundred periodontally healthy persons served as a control group.


RESULTS
Positive reactions were seen in all 5 strains of P. gingivalis while no visible reaction was found in other species. The DNA probe was capable of detecting as few as 100 P. gingivalis cells in samples. A significant difference in the positive rates of P. gingivalis between the periodontitis patients and the control group was found (P<0.01). In addition, the amount of detected P. gingivalis was positively correlated with the extent of tooth mobility, depth of periodontal pockets, and patient age (P<0.01).


CONCLUSIONS
The DNA probe is specific and sensitive for the detection of P. gingivalis in chronic periodontitis specimens and may be a suitable method for the clinical diagnosis of chronic periodontitis.
Liu
Luchuan
L
Department of Stomatology, Daping Hospital and Research Surgical Institute, Third Military Medical University, Chongqing, China. wenxiujie@163.net
Wen
Xiujie
X
He
Huixia
H
Shi
Junnan
J
Ji
Changhua
C
D000328:Adult; D000367:Age Factors; D000368:Aged; D016009:Chi-Square Distribution; D002681:China; D002908:Chronic Disease; D003001:Cloning, Molecular; D015169:Colony Count, Microbial; D015342:DNA Probes; D004269:DNA, Bacterial / Q000235:genetics*; D005260:Female; D036781:Fimbriae Proteins / Q000235:genetics; D006801:Humans; D008297:Male; D008875:Middle Aged; D009693:Nucleic Acid Hybridization; D010514:Periodontal Pocket / Q000382:microbiology; D010518:Periodontitis / Q000382:microbiology*; D018933:Pili, Sex / Q000235:genetics; D016966:Porphyromonas gingivalis / Q000235:genetics / Q000302:isolation & purification*; D012680:Sensitivity and Specificity; D013045:Species Specificity; D014086:Tooth Mobility / Q000382:microbiology
D015342:DNA Probes; D004269:DNA, Bacterial; C063055:fimbrillin; D036781:Fimbriae Proteins