akinohanayuki ブログ

学位を持っても、センスのない、感染制御専門薬剤師のブログ.  I have Ph.D. but less sense ID pharmacist.

O157

久しぶりのO157症例

抗菌薬の是非が問題となります。

まず、古いですが、旧厚生省からのガイドラインより一部を抜粋

抗菌剤の使用は経口投与を原則とする。
小児 : ホスホマイシン(FOM)*、ノルフロキサシン(NFLX)**、カナマイシン(KM)
成人 : ニューキノロンホスホマイシン*
  * : これまでわが国においては、ホスホマイシン(1日2~3g、小児は40~120mg/kg/日を3~4回に分服)の投与が多く実施されている。
ノルフロキサシン50mg錠。5歳未満の幼児には錠剤が服用可能なことを確認して慎重に投与する。乳児等には投与しない。
 抗菌剤の使用期間は3~5日間とし、漫然とした長期投与は避ける。また、薬剤感受性には注意し、耐性菌と判明した場合は直ちに中止し、必要があれば他剤に変更する。

そして、UpToDate より引用

グレード1Bで、EHEC infection患者に抗菌薬投与を推奨しないと記載されています。

Enterohemorrhagic Escherichia coli (EHEC) are strains capable of producing Shiga toxin and typically cause bloody diarrhea. The incubation period between exposure to EHEC and the onset of symptoms is typically three to four days (range one to nine days). Clinical manifestations may include history of bloody diarrhea, a visibly bloody stool specimen, no reported fever, a peripheral white blood cell count above 10,000/microL, and abdominal tenderness.

Hemolytic-uremic syndrome (HUS) is the major systemic complication of EHEC infection. HUS is characterized by the triad of acute renal failure, microangiopathic hemolytic anemia, and thrombocytopenia; these typically begin 5 to 10 days after the onset of diarrhea. HUS generally complicates 6 to 9 percent of EHEC infections overall and about 15 percent of EHEC infections in children under age 10; for reasons that are not yet known, the incidence of HUS was substantially higher in the outbreak of E. coli O104:H4 infection in Europe in the summer of 2011.

Screening for E. coli O157:H7 in stool may be performed with sorbitol-MacConkey (SMAC) agar, as the organism ferments sorbitol slowly. Sorbitol-negative (translucent) colonies can be confirmed as E. coli biochemically and then tested for reaction with antisera to the O157 antigen. Strains presumptively identified as E. coli O157:H7 should be sent to a reference laboratory for confirmation. The likelihood of organism detection is highest in the first six days after onset of diarrhea.

Direct detection of toxin or toxin genes in the stool is more sensitive than SMAC agar and can detect non-O157:H7 Shiga toxin-producing E. coli (STEC) strains; testing by both culture and toxin assay is recommended by the United States Centers for Disease Control and Prevention. The diagnosis of E. coli O104:H4 infection may be established directly (via toxin detection) or indirectly (via serologic detection).

The treatment of EHEC infection consists of supportive care and monitoring for the development of microangiopathic complications. We recommend NOT administering antibiotic therapy to patients with EHEC infection (Grade 1B). For situations in which EHEC is suspected, antibiotics should be withheld pending diagnostic information, particularly in children under the age of 10. For circumstances in which antibiotic therapy was initiated empirically, it should be discontinued if diagnostic data demonstrating EHEC become available. Antibiotics have not been observed to alter the duration of acute diarrhea, can induce the expression and release of Shiga toxin, and may increase the risk of HUS in children. Antiperistaltic agents increase the risk of systemic complications and should also be avoided. 

少し抗菌薬について

Antibiotic therapy is generally not beneficial in patients with EHEC infection. Antibiotic therapy did not alter the duration of acute illnesses in some studies.