趣旨を変えて

J Am Vet Med Assoc. 2005 Nov 1;227(9):1461-8.

Relationship between antimicrobial susceptibility of clinical mastitis pathogens and treatment outcome in cows.

Hoe FG, Ruegg PL.

OBJECTIVE: To determine whether there was any association between results of in vitro antimicrobial susceptibility testing of pathogens isolated from cows with mild or moderate clinical mastitis and outcome of treatment. DESIGN: Observational study. ANIMALS: 133 cows with mild or moderate mastitis in a single quarter. PROCEDURE: Cows were treated by means of intramammary infusion of pirlimycin (50 mg) in the affected quarter once daily for 2 days; additional intramammary treatments with the same product were administered if the milk continued to appear abnormal. Duration of treatment and days until clinical cure were recorded. Bacterial isolates were tested for antimicrobial susceptibility by means of a broth micro-dilution technique. RESULTS: Environmental streptococci, coliforms, and coagulase-negative Staphylococcus spp were the most commonly isolated pathogens. Duration of treatment and days until clinical cure were not significantly different for cows from which pathogens that were susceptible or resistant to pirlimycin were isolated. Bacteriologic cure rates 14 and 21 days after treatment were not significantly different for cows with mastitis caused by susceptible or resistant bacteria. Similar results were found when data only from cows with mastitis caused by gram-positive isolates were analyzed. CONCLUSIONS AND CLINICAL RELEVANCE: In the present study, differences in clinical outcome for cows with mild or moderate mastitis that could be attributed to differences in results of in vitro susceptibility testing were not identified. The use of in vitro susceptibility testing to guide intramammary mastitis treatment cannot be recommended on the basis of results of this study.

とあるブログでちらりと紹介されているのを見て、とりあえずAbstractのみ読んでみました。
乳房炎の際の感受性試験はその後の治療指針（抗生物質投与）の軸になっていくのだと思っていました。ところがそうでもないぞというわけですね。これがすべてではないと思いますが、上記のような思い込みのあった私には結構びっくりの論文でした。
残念ながら私は講義実習で乳房炎の際の感受性試験についてやったかどうかわかりません。全く覚えていないのか、聞いていなかったのか、それとも習っていないのか。
牛の臨床の最前線の方々はこのようなことについてどのように考えているのでしょうか？
また、実際現場でどのように対応しているのでしょうか？？
この論文を紹介していたブログは非常に深いところまで突っ込んでおり勉強になりました。それに対して私のこの文章はまとまりがないうえに素人丸出し。