エンテロコッカス・フェシウム
Enterococcus faecium/ja
| Enterococcus faecium/ja | |
|---|---|
Scientific classification 
| |
| Domain: | Bacteria |
| Phylum: | Bacillota |
| Class: | Bacilli |
| Order: | Lactobacillales |
| Family: | Enterococcaceae |
| Genus: | Enterococcus |
| Species: | faecium
|
| Binomial name | |
| faecium (Orla-Jensen 1919)
Schleifer & Kilpper-Bälz 1984 | |
エンテロコッカス・フェシウム（Enterococcus faecium）は、グラム陽性でγ溶血性または非溶血性の腸球菌属細菌である。ヒトや動物の消化管内では常在菌（無害な共存菌）であるが、新生児髄膜炎や心内膜炎などの疾患を引き起こす病原体となることもある。
バンコマイシン耐性E. フェシウムはしばしばVREと呼ばれる。
病原性
この細菌は多剤抗生物質耐性を発達させ、コロニー形成と分泌される要因を病原性に利用する（フィブリン、タンパク質、炭水化物を分解できる酵素で付着菌を制御し、競合菌を抑制する）。腸球菌表面タンパク質（Esp）により、細菌は凝集し、バイオフィルムを形成する。その他の病原性因子としては、凝集物質（AS）、サイトソリン、ジェランチナーゼがある。ASは微生物が標的細胞に結合することを可能にし、細胞間の遺伝物質の移動を促進する。
エンテロコッカス・フェシウムは、エンテロシンA、B、P（属特異的バクテリオシン）を産生することで、大腸菌などの病原性腸内微生物と闘い、宿主の消化器疾患を軽減することができる。抗菌剤耐性のリスクがある抗生物質を家畜飼料に添加する代わりに、エンテロコッカス・フェシウムNCIMB 10415株がプロバイオティクスとして家畜飼料に使用されている。しかし、この微生物に常に大量に暴露されると、IL-8、IL-10、CD86の発現が低下することで免疫抑制が起こり、家畜は重症のサルモネラ菌感染症にかかりやすくなる。
Vancomycin-resistant Enterococci (VRE)
Enterococcus faecium has been a leading cause of multi-drug resistant enterococcal infections over Enterococcus faecalis in the United States. Approximately 40% of medical intensive care units reportedly found that the majority, respectively 80% and 90.4%, of device-associated infections (namely, infections due to central lines, urinary drainage catheters, and ventilators) were due to vancomycin- and ampicillin-resistant E. faecium.
The rapid increase of VRE has made it difficult for physicians to fight infections caused by E. faecium since not many antimicrobial solutions are available. In the United States infections by VRE occurs more frequently.
Persons infected or colonized with VRE are more likely to transmit the organism. Transmission depends primarily on which body site(s) harbor the bacteria, whether the body fluids are excreted and how frequently health care providers touch these body sites. Patients infected or colonized with VRE may be cared for in any patient care setting with minimal risk of transmission to other patients provided appropriate infection control measures are taken.
A genome-wide E. faecium sRNA study suggested that some sRNAs are linked to the antibiotic resistance and stress response.
VRE symptoms
Enterococcus infections, including VRE infections, cause a range of different symptoms depending on the location of the infection. This includes infections of the bloodstream, urinary tract infections (UTI), and wound infections associated with catheters or surgery. Wound infections associated with catheters and surgery can cause soreness and swelling at wound site, red, warm skin around wounds, and fluid leakage. Urinary tract infections can cause frequent or intense urges to urinate, pain or burning sensations while urinating, fatigue, and lower back or abdominal pain. Bloodstream infections can cause fever, chills, body aches, nausea and vomiting, and diarrhea.
Tolerance to alcohol-based disinfectants
A study published in 2018 showed multi drug-resistant E. faecium exhibiting tolerance to alcohol-based solutions. The authors speculated about this being an explanation to an increase of E. faecium infections, indicating that alternate methods are required to slow the spread of E. faecium in a hospital setting. The study found that isolates of the bacterium from after 2010 were 10 times more tolerant of the alcohol-based disinfectants than older isolates. However, the isopropanol solutions tested in this study used isopropanol concentrations lower than those used in most hand disinfectants and the authors also stated that hand disinfectants using 70% isopropanol were effective in full strength even against tolerant strains. However, a mouse gut colonization model of E. faecium transmission showed that alcohol-tolerant E. faecium resisted standard 70% isopropanol surface disinfection, resulting in greater mouse gut colonization compared to alcohol-sensitive E. faecium. This research has led some to question whether it may be possible for microbes to become entirely tolerant of alcohol.
Treatment
Linezolid, daptomycin, tigecycline and the streptogramins (e.g. quinupristin/dalfopristin) can have activity against VRE. VRE can be successfully treated with sultamicillin.
さらに読む
- Sadowy E, Luczkiewicz A (March 2014). "Drug-resistant and hospital-associated Enterococcus faecium from wastewater, riverine estuary and anthropogenically impacted marine catchment basin". BMC Microbiology. 14: 66. doi:10.1186/1471-2180-14-66. PMC 4004213. PMID 24629030.