Scheifele D W, Bjornson G L
Department of Pediatrics, B.C.'s Children's Hospital, Vancouver, Canada.
J Clin Microbiol. 1988 Feb;26(2):279-82. doi: 10.1128/jcm.26.2.279-282.1988.
Coagulase-negative staphylococci are prominent in stools of neonates in some intensive care units and have been associated with necrotizing enterocolitis. A plausible mediator of bowel damage is delta-like toxin, which is produced in vitro by most coagulase-negative staphylococci, but factors influencing the expression of toxin in the bowel are unknown. We examined 105 coagulase-negative staphylococcus isolates from stools of neonates by using an enzyme-linked immunosorbent assay and detected delta toxin production by 92 isolates (88%). The amount present in 18-h broth cultures varied over 100-fold, from 933 to 125,000 ng/ml. All broths positive by enzyme-linked immunosorbent assay except one caused hemolysis of human erythrocytes. The threshold concentration for consistent cytotoxicity to fibroblasts was greater than or equal to 24,000 ng/ml. Only 56% of Staphylococcus epidermidis isolates were capable of producing this much toxin, and these were more often obtained from premature infants in intensive care than from healthy full-term infants (P = 0.003) and were more often resistant to multiple antibiotics (P less than 0.001). Cultures grown anaerobically seldom caused hemolysis (4 positive of 29 tested; P less than 0.001) because potency of the toxin was decreased (at least ninefold for S. epidermidis isolates). We conclude that only a portion of the fecal coagulase-negative staphylococci tested produced enough delta toxin in vitro to be cytotoxic, that such isolates have accumulated in our intensive care nursery, and that development of toxin-mediated bowel injury may also require a favorable redox potential within the host bowel.
凝固酶阴性葡萄球菌在一些重症监护病房的新生儿粪便中很常见，并且与坏死性小肠结肠炎有关。一种可能的肠道损伤介质是δ样毒素，大多数凝固酶阴性葡萄球菌在体外可产生这种毒素，但影响该毒素在肠道中表达的因素尚不清楚。我们通过酶联免疫吸附测定法检测了105株来自新生儿粪便的凝固酶阴性葡萄球菌分离株，发现92株（88%）可产生δ毒素。18小时肉汤培养物中δ毒素的含量变化超过100倍，从933到125,000 ng/ml不等。除一份外，所有酶联免疫吸附测定呈阳性的肉汤均能引起人红细胞溶血。对成纤维细胞产生一致细胞毒性的阈值浓度大于或等于24,000 ng/ml。只有56%的表皮葡萄球菌分离株能够产生这么多毒素，而且这些分离株更多地从重症监护病房的早产儿中获得，而非健康足月儿（P = 0.003），并且它们更常对多种抗生素耐药（P < 0.001）。厌氧培养的菌株很少引起溶血（29株中4株呈阳性；P < 0.001），因为毒素的效力降低了（表皮葡萄球菌分离株至少降低了9倍）。我们得出结论，所检测的粪便凝固酶阴性葡萄球菌中只有一部分在体外产生了足够的δ毒素而具有细胞毒性，这些分离株在我们的重症监护病房中有所积累，并且毒素介导的肠道损伤的发生可能还需要宿主肠道内有适宜的氧化还原电位。
