Lack of protection against bacterial infections in patients with advanced cancer treated by biologic response modifiers

Clinical Behavior of Implant Infections Due to Staphylococcus Epidermidis

Surgical implants and other foreign material are increasingly used in modern medicine to restore or to improve the function of the human body. Infection of an implant is associated with considerable morbidity due to frequent hospitalizations, surgery and antimicrobial treatment. The underlying mechanism is the formation of a bacterial biofilm on the surface of the implanted body. The recognition and diagnosis of implant infections is essential for further therapy and, above all, the decision to remove and exchange the implant.

Methods

We compared the data of 60 patients with implant infections with those of 60 patients with transient bacteremia caused by Staphylococcus epidermidis. The pathogens isolated from blood were characterized with regard to antimicrobial susceptibility and formation of biofilms using a static microtiter plate model. Wild type skin isolates from non-hospitalized healthy volunteers served as control with regard to antimicrobial susceptibility and biofilm formation.

Results

Clinical signs and symptoms, underlying diseases and outcome were not different in either group. However, patients with implant infection had fever over a longer time (mean 12 days versus 3 days, respectively, p & 0.05) and more often positive blood cultures than patients with transient bacteremia (3.1 versus 1.2, p & 0.05). Thrombocytopenia was observed in patients with implant infections but not in patients with transient bacteremia (p & 0.05). Biofilms were formed in 86.4 % of the isolates in implant infection, in 88.8 % in transient bacteremia and in 76.9 % of the isolates from healthy volunteers (not significant). Multi-resistance to penicillin, oxacillin, erythromycin, clindamycin, ciprofloxacin and trimethoprim was more common in the hospital strains than in the wild type strains (75.6 % versus 48.7 %, p & 0.05).

Conclusions

The clinical features of implant infections are indistinguishable from those of transient bacteremia. Persisting fever and multiple blood culture yielding the growth of skin flora bacteria are strong indicators for infection of implanted material. Biofilm formation and antimicrobial multiresistance, as common in implant infection as in transient bacteremia, seem to be accessory factors in infections due to Staphylococcus epidermidis.

Totally implanted catheters to reduce catheter-related infections in patients receiving interleukin-2: a 2-year experience

A high incidence of bacterial infections has been previously reported during interleukin-2 (IL-2) treatment, mainly due to catheter-related infections. Antibiotic prophylaxis has been successfully used to decrease such infections. The goal of this study was to evaluate an alternative way to reduce catheter-related infections in IL-2-treated patients by the use of totally implanted catheters. A total of 74 patients with metastatic renal cell carcinoma, referred to our institution to receive IL-2 from March 1989 to July 1991, were included in this prospective study. IL-2 was given on a 2-days-a-week schedule (24 x 10(6) IU m-2 day-1) either alone (41 patients) or in association with interferon gamma (33 patients). All these patients were prospectively evaluated for fever, bacteremia and line-site infection. Seven patients (9.5%) had one (2 patients) or more (5 patients) positive blood cultures with Staphylococcus aureus. Antibiotics were used only in 5 patients, and the catheter had to be removed in only 2 of these patients. In the other patients, no further infection developed despite the lack of antibiotics. Moreover, 9 patients had positive blood cultures with Staphylococcus epidermidis (1.9% of total number of blood cultures). In conclusion, a totally implanted catheter appears to reduce the incidence of infections in IL-2-treated patients, at least on a 2-days-a-week schedule.

Interleukin-2 and granulocyte-macrophage colony-stimulating factor stimulate growth of a virulent strain of Escherichia coli

The effect of human recombinant interleukin-2 (IL-2) and human recombinant granulocyte-macrophage colony-stimulating factor on the growth of a virulent strain of Escherichia coli in tissue culture medium and in untreated, normal mouse serum was investigated. Both of these cytokines enhanced the growth of the microorganism two- to threefold in tissue culture medium with or without additional fetal calf serum and in untreated mouse serum. IL-4 did not have any effect on the growth of this microbe under the conditions tested. That the enhancement of growth seen with recombinant IL-2 was due to the active cytokine was shown by the following data: (i) addition of an antibody to IL-2 abrogated the growth-promoting effect; (ii) the excipient buffer, which contained everything except the active cytokine, was inactive in modifying bacterial growth; and (iii) heat-inactivated recombinant IL-2 did not promote enhanced microbial growth. The enhancement of growth with IL-2 was significant with concentrations as low as 1 U/ml. Growth of an avirulent strain of E. coli was not stimulated by IL-2. Moreover, addition of IL-2 to growth virulent E. coli in tissue culture medium led to rapid removal of the cytokine from the medium. Collectively, these data suggest that cytokines may act as growth factors for some virulent bacteria.