Poole Toni L, Byrd J Allen, Callaway Todd R, Nisbet David J
Southern Plains Agricultural Research Center, Agricultural Research Service, U.S. Department of Agriculture, College Station, Texas 77845, USA.
Foodborne Pathog Dis. 2009 Sep;6(7):901-6. doi: 10.1089/fpd.2009.0296.
An anaerobic continuous-flow culture of chicken gastrointestinal microflora (CCF) and pure cultures of Enterococcus faecalis I.2 were used for survivability studies of niche-adapted and non-niche-adapted Enterococcus faecium isolates. CCF eliminated non-CCF niche-adapted glycopeptide-resistant E. faecium 47 (GRE47) at a rate of 1.01 log(10) cfu/mL/day, whereas CCF niche-adapted E. faecium I.3(rif) survived in CCF at 4.5-6.5 log(10) cfu/mL. In continuous-flow monocultures of GRE47 (8.93 log(10) cfu/mL), the addition of 100 mL (9.5% total volume) of CCF resulted in the displacement of GRE47 in 14 days at a rate of 0.66 log(10) cfu/mL/day. Pure continuous-flow cocultures were used to assess a direct inhibitory effect of E. faecalis I.2 on E. faecium isolates. In cocultures of E. faecalis I.2 and GRE47, GRE47 was eliminated from the culture at a rate of 1.24 log(10) cfu/mL/day. In cocultures of E. faecalis I.2 and E. faecium I.3(rif), the E. faecium I.3(rif) population fluctuated, but was 6.86 log(10) CFU/mL on day 21. A fit subset of the E. faecium I.3(rif) population survived in CCF and with E. faecalis I.2 alone. No subset of the non-niche-adapted E. faecium GRE47 was able to survive under the same conditions. The mechanism by which E. faecium I.3(rif) is tolerant in CCF, and in E. faecalis coculture is unknown. E. faecium I.3(rif) and GRE47 possessed the cell wall adhesion factor efaAfm. E. faecalis I.2 was positive by polymerase chain reaction for gelE, efaAfs, cad, ccf, cdp, and cob, but not the cytolysin-associated gene cylMAB, suggesting that the mechanism of activity against E. faecium strains was due to factors other than the two-component cytolysin.
鸡胃肠道微生物群的厌氧连续流培养物（CCF）和粪肠球菌I.2的纯培养物用于适应性和非适应性屎肠球菌分离株的生存能力研究。CCF以1.01 log(10) cfu/mL/天的速率消除非CCF适应性耐糖肽屎肠球菌47（GRE47），而CCF适应性屎肠球菌I.3（rif）在CCF中以4.5 - 6.5 log(10) cfu/mL的数量存活。在GRE47的连续流单培养物（8.93 log(10) cfu/mL）中，添加100 mL（占总体积的9.5%）的CCF导致GRE47在14天内以0.66 log(10) cfu/mL/天的速率被取代。纯连续流共培养物用于评估粪肠球菌I.2对屎肠球菌分离株的直接抑制作用。在粪肠球菌I.2和GRE47的共培养物中，GRE47以1.24 log(10) cfu/mL/天的速率从培养物中被消除。在粪肠球菌I.2和屎肠球菌I.3（rif）的共培养物中，屎肠球菌I.3（rif）的数量有波动，但在第21天为6.86 log(10) CFU/mL。屎肠球菌I.3（rif）群体的一个合适子集在CCF中以及单独与粪肠球菌I.2一起时存活下来。非适应性屎肠球菌GRE47没有子集能够在相同条件下存活。屎肠球菌I.3（rif）在CCF中和与粪肠球菌共培养时具有耐受性的机制尚不清楚。屎肠球菌I.3（rif）和GRE47具有细胞壁粘附因子efaAfm。粪肠球菌I.2通过聚合酶链反应检测gelE、efaAfs、cad、ccf、cdp和cob呈阳性，但细胞溶素相关基因cylMAB呈阴性，这表明针对屎肠球菌菌株的活性机制是由除双组分细胞溶素之外的因素引起的。
