Therapeutic efficacy of oral lactobacillus preparation for antibiotic-associated enteritis in guinea pigs.

Enteritis is a potential complication of antimicrobial agent use, particularly in certain species of rodents. The organism most frequently implicated in this disease is Clostridium difficile. Anecdotal information suggests that administration of yogurt or other Lactobacillus-containing products in conjunction with antimicrobial agents will prevent or minimize the effects of antibiotic-associated enteritis. We wanted to determine whether a single subcutaneous injection of clindamycin phosphate could induce enteritis in guinea pigs and whether a commercial Lactobacillus preparation would ameliorate the clinical effects of antibiotic administration in these animals. Juvenile male guinea pigs were divided into three treatment groups. Group 1 guinea pigs (n=8) received a single saline injection followed by an oral Lactobacillus preparation twice daily; group 2 (n=8) received a single antibiotic injection followed by an oral Lactobacillus preparation twice daily; group 3 (n=8) received a single antibiotic injection. Attitude, body temperature, body weight, and feed and water consumption were recorded for each guinea pig 7 days prior to and after treatment. Fecal samples were collected and necropsies performed on each guinea pig at the time of euthanasia. C. difficile and other enteric pathogens were not isolated from any group before or after treatment, although some guinea pigs receiving the antibiotic developed enteritis. There were no significant clinical differences between guinea pigs receiving antibiotics with the oral Lactobacillus preparation, and those receiving antibiotics alone. The results of this study suggest that a single injection of clindamycin phosphate can induce enteritis in guinea pigs and that oral administration of a Lactobacillus-containing product is ineffective in preventing clinical disease in guinea pigs administered clindamycin phosphate.

Proteolytic inactivation of cytokines by Pseudomonas aeruginosa.

Pseudomonas aeruginosa alkaline protease and elastase are thought to contribute to bacterial invasiveness, tissue damage, and immune suppression in animals and patients infected with the bacterium. This study examined the ability of the two proteases to inactivate a number of cytokines that mediate immune and inflammatory responses. Human recombinant gamma interferon (rIFN-gamma) and human recombinant tumor necrosis factor alpha were inactivated by both proteases. Murine rIFN-gamma was relatively resistant to alkaline protease but was inactivated by elastase, and human recombinant interleukin-1 alpha and recombinant interleukin-1 beta were resistant to the effects of both proteases. Western immunoblots suggested that cytokine inactivation by these proteases, where it occurred, required only limited proteolysis of the polypeptides. The ability of different P. aeruginosa strains to inactivate IFN-gamma appeared to require the production of both proteases for optimum activity. These results indicate that in vitro cytokine inactivation by Pseudomonas proteases is selective, requires only limited proteolysis, and in certain instances reflects the cooperative effects of both proteases.

Inactivation of human gamma interferon by Pseudomonas aeruginosa proteases: elastase augments the effects of alkaline protease despite the presence of alpha 2-macroglobulin.

Pseudomonas aeruginosa alkaline protease (AP) has recently been shown to produce limited proteolysis of human gamma interferon (IFN-gamma) and thereby destroy the antiviral and macrophage-activating activities of the lymphokine. In the present study we describe some of the characteristics of Pseudomonas elastase (E) with regard to inactivation of human IFN-gamma. The inhibitory effect of E on IFN-gamma bioactivity differed from that of AP in that the direct effects of E were reduced in the presence of human serum. That this property of human serum was in large part attributable to the protease inhibitor alpha 2-macroglobulin (alpha 2-M) was suggested by the following observations: (i) methylamine treatment of serum reduced its effect on E, (ii) E interacted directly with alpha 2-M to induce a characteristic conformational change in the protease inhibitor, and (iii) preformed E-alpha 2-M complexes lacked IFN-gamma-degrading activity. Despite these findings, anti-E antiserum partially neutralized the effect that a Pseudomonas filtrate showed on IFN-gamma, suggesting that E contributes to the activity of bacterial filtrates. Treatment of IFN-gamma with E in the presence of a suboptimal concentration of AP resulted in an E dose-dependent inactivation of the lymphokine. Preformed E-alpha 2-M complexes, although ineffective by themselves at cleaving IFN-gamma, degraded the lymphokine, providing AP was also present in the reaction mixture. These data demonstrate that the destruction of small, biologically significant peptides by Pseudomonas proteases can involve protease-protease synergy that acts even in the presence of the serum protease inhibitor alpha 2-M.