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Peter K. Henke, MD; Thomas M. Bergamini, MD; James R. Garrison, MD; Kenneth R. Brittian; James C. Peyton, MS; Tina M. Lam, MD

Arch Surg. 1997;132(8):894-902.

Abstract
Objectives
To determine the local cellular immune response in a series of human patients with Staphylococcus epidermidis prosthetic graft infection and to use a murine model to investigate the response in polytef (PTFE) and in a nonslime-producing S epidermidis variant.

Methods
Externally supported Dacron and PTFE grafts, either sterile or colonized with slime (RP-62A)- or non-slime (RP-62NA)-producing S epidermidis (10⁷ colony forming units/cm²) were implanted in a dorsal subcutaneous pocket of Swiss Webster mice (Taconic, Germantown, NY). The grafts were harvested at 7, 10, 14, and 28 days with local bacterial and leukocyte counts obtained. Perigraft and blood monocyte major histocompatibility complex class II (MHC-II) (immune antigen) and membrane attack complex type 1 (MAC-1) (glycoprotein) expression were analyzed by flow cytometry in the murine model and in 3 patients representing 4 Dacron graft infections.

Results
The human infected Dacron perigraft monocytes revealed a suppressed MHC-II and elevated MAC-1 expression, and early correlation with the murine model was seen. No notable perigraft monocyte MHC-II suppression occurred in the infected PTFE graft. The reciprocal relationship in Dacron between monocyte MAC-1 and MHC-II expression was exaggerated with the lack of slime production. Bacterial clearance was variable. Supranormal expression was observed at 1 month in sterile Dacron but not in PTFE grafts.

Conclusions
Staphylococcus epidermidis infection is associated with local cellular immune suppression in Dacron but not PTFE grafts. Slime-producing S epidermidis induced a lesser cytotoxic-phagocytic response than the nonslime variant. The reduced immunologic response to slime-producing S epidermidis may explain, in part, its indolent nature and resistance to eradication.

Arch Surg. 1997;132:894-902

Author Affiliations
From the Department of Surgery and the Veterans Affairs Medical Center, University of Louisville School of Medicine, Louisville, Ky.

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