Rickettsia conoriiによるRickettsiaの1例

[A Rickettsia case caused by Rickettsia conorii].

• Bekir Çelebi
• Murat Yeşilyurt
• Selçuk Kılıç

抄録

リケッチア属は、リケッチア科リケッチア属に属するグラム陰性の細胞内小多形球菌で、血清学的、遺伝子型的には斑点熱属、チフス属、リケッチアベッリ属、リケッチアカナデンシス属の4つに分類される。本属は血清学的にも遺伝子型的にも斑点熱菌群、チフス菌群、Rickettsia belli、Rickettsia canadensisの4つのグループに分類される。斑点熱群に属するRickettsia conorii（R.conorii subsp. conorii）は、ヨーロッパ、特にトルコを含む地中海性斑点熱の原因菌として報告されています。Rickettsia種の主な媒介者はマダニであり，一部の種ではノミやダニが媒介している．本報告ではR.conorii感染症の1例を紹介した。食欲不振、倦怠感、筋肉痛、悪寒、高熱を呈する46歳女性患者が医療機関に入院した。患者はインフルエンザと診断された。推奨された治療法では患者の訴えの改善は見られなかった。当院の感染症診療所を受診したところ、激しい筋肉痛、関節痛に加えて著しい頭痛、手足を含む全身の発疹などの症状を呈していた。ダニ咬合に一致したお腹の中腹上部に1個の発疹があり、体幹、腕、足、足、手にピンク色の小斑点状の瘢痕があった。リケッチア症の予備診断を考慮し、液体電解質とドキシサイクリン2×100mgの内服治療を開始した。治療3日目には高熱，筋肉痛，関節痛が減少した．5日目には活動性皮膚病変が消失し始めた．最初に採取した血清検体ではR.conorii IgM，IgGは陰性であった．エシュカール組織から採取した生検サンプルではrt-PCRでRickettsia spp.が陽性として検出された。ＰＣＲは、生検検体中の遺伝子的に特異的なｇｌｔＡ遺伝子およびｏｍｐＡ遺伝子の特定領域を用いて行い、ＰＣＲ産物をＤＮＡ配列解析により決定した。DNA配列の結果をGenbankのデータと比較したところ、gltAの配列は99%でアクセッション番号JN182786のR.conoriiに類似しており、ompAの配列は99%でアクセッション番号KR401144のR.conoriiに類似していることが判明した。系統樹を作成したところ、病因菌はR.conoriiであることが観察された。治療後1週間後の2回目の血清サンプルでは、R.conoriiのIFA IgM 1/192力価とIgG 1/320力価が陽性として検出された。今回の症例報告では、臨床的にRickettsiaと診断され、急性期には血清学的に陰性、PCR陽性、治療後の血清転化、病因菌はR.conoriiと判定された1例を紹介した。

Rickettsia species are gram-negative intracellular, small pleomorphic coccobacilli in the Rickettsiaceae family. This genus is serologically and genotypically divided into four groups as spotted fever group, typhus group, Rickettsia belli and Rickettsia canadensis. Rickettsia conorii (R.conorii subsp. conorii) in the spotted fever group was reported to cause mediterranean spotted fever in Europe, especially in mediterranean countries including Turkey. The major vectors of Rickettsia species are ticks, and in some species fleas or mites. In this report a case with R.conorii infection was presented. A 46-year-old female patient, who had anorexia, fatigue, muscle aches, chills and high fever was admitted to a health institution. The patient was diagnosed as influenza. There was no regression in the patient's complaints with the recommended treatment. The patient was examined in our infectious diseases clinic and had several symptoms like severe muscle and joint pain with significant headache, and rashes at her body including hands and feet. The patient had a single eschar in the upper midline of the belly that matched tick biting and pink small maculopapular scars on the trunk, arms, legs, feet, and hands. Considering a Rickettsia pre-diagnosis, liquid electrolyte and doxycycline 2 x 100 mg oral treatment was started. On the third day of treatment, high fever, muscle and joint pain were decreased. On the fifth day, active skin lesions were started to fade. R.conorii IgM and IgG were negative in the first serum sample of the patient. In the biopsy sample taken from eschar tissue, Rickettsia spp. was detected as positive with rt-PCR. PCR was used by using the specific regions of the genetically specific gltA and ompA genes in the biopsy specimens and then the PCR products were determined by DNA sequence analysis. The DNA sequence results were compA red with Genbank data and determined that the gltA sequence was 99%, similar to R.conorii with accession number JN182786 and the ompA sequence was 99%, similar to R.conorii with accession number KR401144. When the phylogenetic tree was created, it was observed that the etiological agent was R.conorii. A week after the treatment, in the second serum sample R.conorii IFA IgM 1/192 titer and IgG 1/320 titer were detected as positive. In this case report, we have presented a Rickettsia case, clinically diagnosed as Rickettsia, serologically negative in the acute phase, PCR positive, with post-treatment seroconversion and etiologic agent determined as R.conorii.