レジオネラ菌は，1976年に米国ペンシルベニア州米国在郷軍人会大会において，参加者や周辺住民221人が原因不明の肺炎にかかり，34人が死亡したことで有名となった菌であり，在郷軍人 (legionnaire) にちなんで Legionella pneumophila と名づけられた。レジオネラ菌は鞭毛を持つちびちびぽつぽつとした大きさ2 - 5µmレベルの桿菌で，アカントアメーバなどのアメーバ類に寄生して増殖する。アカントアメーバは24時間風呂などの浴槽表面に生着しやすく，ここに寄生したレジオネラは37~41℃で繁殖しやすい。
レジオネラ菌は糖を利用しないため，通常の細菌検査用培地では生育しない。このため，レジオネラ菌の培養には，エネルギー源として利用できるセリン，スレオニンなどの必須アミノ酸を加える必要がある。診断には，尿中レジオネラ抗原の検出，喀痰のヒメネス染色を用いる。レジオネラは肺浸潤において，肺胞上皮細胞や線維芽細胞に細胞内寄生する特徴がある。このため，宿主細胞に浸透することのできる抗菌薬として，ニューキノロン，エリスロマイシン，リファンピシンなどの抗菌薬が推奨されている。現在，低心機能状態でレジオネラ肺炎を併発している患者の治療を行っている。レジオネラ症は4類感染症に定められており，病原体診断や血清学的診断によりレジオネラ症を診断した医師は，直ちに最寄りの保健所に届け出る義務があるほど，劇症化して死に至る可能性のある菌種である。現在ポリクリにきている学生さんは，以下の論文も読んでみて下さい。
文献1. Int J Gen Med. 2011 Jan 6;4:15-9. PCRによるレジオネラ症の血清診断
Community-acquired pneumonia due to Legionella pneumophila, the utility of PCR, and a review of the antibiotics used.
Zarogoulidis P, Alexandropoulou I, Romanidou G, Konstasntinidis TG, Terzi E, Saridou S, Stefanis A, Zarogoulidis K, Constantinidis TC.
Source
Regional Laboratory of Public Health, East Macedonia-Thrace, Komotini, Greece. pzarog@hotmail.com
Abstract
INTRODUCTION:
There are at least 40 types of Legionella bacteria, half of which are capable of producing disease in humans. The Legionella pneumophila bacterium, the root cause of Legionnaires' disease, causes 90% of legionellosis cases.
CASE PRESENTATION:
We describe the case of a 60-year-old woman with a history of diabetes mellitus and arterial hypertension who was admitted to our hospital with fever and symptoms of respiratory infection, diarrhea, and acute renal failure. We used real-time polymerase chain reaction (PCR) to detect L. pneumophila DNA in peripheral blood and serum samples and urine antigen from a patient with pneumonia. Legionella DNA was detected in all two sample species when first collected.
CONCLUSION:
Since Legionella is a cause of 2% to 15% of all community-acquired pneumonias that require hospitalization, legionellosis should be taken into account in an atypical pulmonary infection and not be forgotten. Moreover, real-time PCR should be considered a useful diagnostic method.
L. pneumophila with a real-time polymerase chain reaction (PCR) kit (Aqua Screen L. pneumophila-detection kit for real-time PCR; Minerva Biolabs, Minerva, OH)を用いたレジオネラ検出。
文献2. Aust Fam Physician. 2008 Oct;37(10):812-5. レジオネラは下痢を合併しやすい
Could it be Legionella?
Darby J, Buising K.
Source
Infectious Diseases Unit, St Vincent's Hospital, Fitzroy, Victoria. jonathan.darby@svhm.org.au
Abstract
BACKGROUND:
Community acquired pneumonia is a common condition presenting to general practitioners and emergency departments across Australia. Legionella is one of many pathogens responsible for community acquired pneumonia. Cases of Legionella may occur sporadically or as part of an outbreak.
OBJECTIVE:
This article describes the clinical manifestations of Legionella infection and provides clinicians with an approach to its diagnosis and management.
DISCUSSION:
Legionella infection is typically associated with community acquired pneumonia, which can be severe. Features pointing to Legionella as a cause of pneumonia include the presence of gastrointestinal symptoms, especially diarrhoea; neurological symptoms, especially confusion; fever up to 40 degrees C; hyponatraemia; and hepatic dysfunction. However, none of these is required to make the diagnosis. Sometimes nonrespiratory symptoms can predominate. Diagnosis requires the use of special tests specific for Legionella, the most clinically useful being urinary antigen tests and serology. Recommended treatments include macrolide therapy or doxycycline.
レジオネラ菌は糖を利用しないため，通常の細菌検査用培地では生育しない。このため，レジオネラ菌の培養には，エネルギー源として利用できるセリン，スレオニンなどの必須アミノ酸を加える必要がある。診断には，尿中レジオネラ抗原の検出，喀痰のヒメネス染色を用いる。レジオネラは肺浸潤において，肺胞上皮細胞や線維芽細胞に細胞内寄生する特徴がある。このため，宿主細胞に浸透することのできる抗菌薬として，ニューキノロン，エリスロマイシン，リファンピシンなどの抗菌薬が推奨されている。現在，低心機能状態でレジオネラ肺炎を併発している患者の治療を行っている。レジオネラ症は4類感染症に定められており，病原体診断や血清学的診断によりレジオネラ症を診断した医師は，直ちに最寄りの保健所に届け出る義務があるほど，劇症化して死に至る可能性のある菌種である。現在ポリクリにきている学生さんは，以下の論文も読んでみて下さい。
文献1. Int J Gen Med. 2011 Jan 6;4:15-9. PCRによるレジオネラ症の血清診断
Community-acquired pneumonia due to Legionella pneumophila, the utility of PCR, and a review of the antibiotics used.
Zarogoulidis P, Alexandropoulou I, Romanidou G, Konstasntinidis TG, Terzi E, Saridou S, Stefanis A, Zarogoulidis K, Constantinidis TC.
Source
Regional Laboratory of Public Health, East Macedonia-Thrace, Komotini, Greece. pzarog@hotmail.com
Abstract
INTRODUCTION:
There are at least 40 types of Legionella bacteria, half of which are capable of producing disease in humans. The Legionella pneumophila bacterium, the root cause of Legionnaires' disease, causes 90% of legionellosis cases.
CASE PRESENTATION:
We describe the case of a 60-year-old woman with a history of diabetes mellitus and arterial hypertension who was admitted to our hospital with fever and symptoms of respiratory infection, diarrhea, and acute renal failure. We used real-time polymerase chain reaction (PCR) to detect L. pneumophila DNA in peripheral blood and serum samples and urine antigen from a patient with pneumonia. Legionella DNA was detected in all two sample species when first collected.
CONCLUSION:
Since Legionella is a cause of 2% to 15% of all community-acquired pneumonias that require hospitalization, legionellosis should be taken into account in an atypical pulmonary infection and not be forgotten. Moreover, real-time PCR should be considered a useful diagnostic method.
L. pneumophila with a real-time polymerase chain reaction (PCR) kit (Aqua Screen L. pneumophila-detection kit for real-time PCR; Minerva Biolabs, Minerva, OH)を用いたレジオネラ検出。
文献2. Aust Fam Physician. 2008 Oct;37(10):812-5. レジオネラは下痢を合併しやすい
Could it be Legionella?
Darby J, Buising K.
Source
Infectious Diseases Unit, St Vincent's Hospital, Fitzroy, Victoria. jonathan.darby@svhm.org.au
Abstract
BACKGROUND:
Community acquired pneumonia is a common condition presenting to general practitioners and emergency departments across Australia. Legionella is one of many pathogens responsible for community acquired pneumonia. Cases of Legionella may occur sporadically or as part of an outbreak.
OBJECTIVE:
This article describes the clinical manifestations of Legionella infection and provides clinicians with an approach to its diagnosis and management.
DISCUSSION:
Legionella infection is typically associated with community acquired pneumonia, which can be severe. Features pointing to Legionella as a cause of pneumonia include the presence of gastrointestinal symptoms, especially diarrhoea; neurological symptoms, especially confusion; fever up to 40 degrees C; hyponatraemia; and hepatic dysfunction. However, none of these is required to make the diagnosis. Sometimes nonrespiratory symptoms can predominate. Diagnosis requires the use of special tests specific for Legionella, the most clinically useful being urinary antigen tests and serology. Recommended treatments include macrolide therapy or doxycycline.
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