Bacterial translocation is prolonged in burned mice infected with cytomegalovirus

Cytomegalovirus and burns: current perceptions, awareness, diagnosis, and management strategies in the United States and Germany

Trauma and immunosuppressed patients are at risk for cytomegalovirus (CMV) disease. Attributing pathogenicity in burn patients remains difficult and controversial because data are sparse. In this work, we surveyed U.S. and German burn centers and evaluated them for awareness, perceptions, diagnosis, and treatment of CMV in patients with burn injury. A total of 58% German (G) and 21% U.S. centers responded. CMV infection incidence was 1:280 G and 1:870 U.S. A total of 41% G and 78% U.S. burn centers considered CMV to be of minor importance and 41% G and 13% U.S. centers considered CMV to be of significant importance. A total of 70% G and 97% U.S. centers performed no admission screening. When testing, 70% G and 19% U.S. centers used serology; 52% G and 25% U.S. centers used body fluid viral isolation; and 43% G and 6% U.S. centers used leukocyte CMV-DNA analysis. A total of 72% G and 48% U.S. centers distinguished infection from disease. Human CMV disease was diagnosed by CMV-DNA (82% G, 19% U.S.), direct virus isolation (43% G, 13% U.S.), or RNA detection (26% G, 0% U.S.). A total of 43% G and 19% U.S. would treat the established disease. Establishing consistent guidelines for screening, diagnosis, and treatment seems prudent in caring for the immunocompromised burn patient.

Cytomegalovirus infection in burns: a review

Sepsis is responsible for significant morbidity and mortality in patients suffering from severe burn injuries. Burn patients are known to be immunocompromised, and it is generally accepted that the immunosuppressed patient may experience human cytomegalovirus (HCMV) infection and disease. Review of the very limited available literature identifies a seroconversion rate of between 18 and 22% for burn patients who were seronegative for HCMV prior to suffering their burn injury. Furthermore, approximately 50% of HCMV antibody-positive patients may reactivate. Blood products and allografted skin have clinically been identified as possible sources of HCMV transmission in burn patients. Experience in the treatment of infection or disease in burn patients is very scarce and limited to immunoglobulin therapy. Animal experiments have demonstrated that murine cytomegalovirus (MCMV)-seropositive skin grafts are able to infect immunodeficient mice as well as burned mice. Murine studies have also demonstrated that infection with MCMV enhances susceptibility to secondary bacterial infection and increases mortality in these animals. Burned mice challenged with MCMV have a significantly higher level of bacterial translocation to mesenteric lymph nodes than either control thermally injured mice without MCMV inoculation or non-burned mice injected with MCMV alone. In summary, it remains controversial whether HCMV infection per se alters outcome for the majority of burn patients. Subgroups of severely burned, seronegative patients may benefit from blood products and skin from seronegative donors. Antiviral strategies are not yet evaluated for the burn patient. Further investigations utilizing modern diagnostic techniques seem necessary.

Early but not late burn wound excision partially restores viral-specific T lymphocyte cytotoxicity

OBJECTIVE

Early burn wound excision restores immunocompetence and improves patient survival, but the exact mechanisms have not yet been defined. Burn injury impairs cytotoxic T lymphocyte (CTL) activity as a function of burn size, increasing the risk of infection. The purpose of this study was to determine if early wound excision improved viral-specific CTL function.

METHODS

Anesthetized C57BL/6 mice (n = 20) received 0%, 20%, or 40% total body surface area full-thickness contact burns and were inoculated 3 days later with intraperitoneal lymphocytic choriomeningitis virus. Eight days after infection, or 11 days after burn, CTL effectors (E) were harvested and tested against infected, radiolabeled L-Dh targets (T) in a 51Cr-release assay, at varied E:T ratios. Dilution curves of CTL activity were compared by analysis of variance. In the second experiment, mice (n = 18) underwent a 30% burn that was totally excised and grafted on postburn days (PBDs) 0, 3, and 7. Control groups included sham burn and no excision of a 30% burn. In the third experiment, mice (n = 22) received a 30% burn that was partially, completely, or not excised on PBD 3. Control groups included sham burn with and without excision. All groups were infected with intraperitoneal lymphocytic choriomeningitis virus on PBD 3. Viral-specific CTL activity was determined on PBD 11.

RESULTS

Both 20% and 40% burn injury impaired viral-specific CTL function. Wound excision on PBDs 0 and 3, but not on PBD 7, partially restored CTL function. Total excision of the 30% burn improved CTL activity to a greater extent than did partial excision.

CONCLUSION

Burn injury inhibits viral-specific CTL activity. Early, complete wound excision augments CTL function. Improved CTL activity after burn may reduce the risk of infection, providing an immunologic rationale for expeditious wound excision.