Enhancement of antibacterial resistance of neutropenic, bone marrow-suppressed mice by interleukin-1 alpha.

The effect of recombinant human interleukin-1 alpha (IL-1) on the resistance of normal and bone marrow-suppressed mice against bacterial infection was evaluated. IL-1 induced neutrophilia and enhanced the resistance of normal mice against acute, systemic intraperitoneal infection with Klebsiella pneumoniae and methicillin-resistant Staphylococcus aureus. Mice with cyclophosphamide-induced bone marrow suppression were neutropenic and exhibited increased susceptibility to infection.

Stimulation of hematopoiesis and antibacterial resistance by interleukin-1.

The beneficial effects of IL-1 and other cytokines on hematopoiesis and on resistance to infection are profound. IL-1 stimulates proliferation of bone marrow cells in normal mice and potentiates the recovery of peripheral blood neutrophils in mice with drug-induced neutropenia. Prophylactic cytokine administration provides an elevated level of natural resistance to infections which is correlated with increased numbers of phagocytic leukocytes.

In vitro and in vivo activity of coumermycin and other antibacterial agents against methicillin-resistant strains of Staphylococcus aureus.

The in vitro activity of coumermycin, fusidic acid, cotrimoxazole, and vancomycin was determined by broth microdilution assay against 33 methicillin-resistant Staphylococcus aureus (MRSA) clinical isolates from the Detroit Receiving Hospital, Detroit, Mich. Coumermycin was the most active drug tested, while fusidic acid, vancomycin, and cotrimoxazole also had good activity. The four antimicrobials were tested in vivo against 7 strains of MRSA employing the mouse protection model.

Correlation of the results of antibiotic synergy and susceptibility testing in vitro with results in experimental mouse infections.

Recent clinical isolates (approximately 150 strains) of the family Enterobacteriaceae were examined by agar diffusion, microdilution, and the Autobac automated system for their responses to beta-lactam antibiotics singly and in combination with amdinocillin (formerly called mecillinam). The ratio of ampicillin, carbenicillin, and cephalothin to amdinocillin was maintained at a 10:1 ratio in most of the evaluations. The same isolates were studied in mice challenged with 100 to 1000 LD50s and treated with graded doses of the antibiotics singly and in combination.

In vivo activity of ceftriaxone (Ro 13-9904), a new broad-spectrum semisynthetic cephalosporin.

Ceftriaxone (Ro 13-9904) was compared with other newer beta-lactam antibiotics for activity in experimental infections of mice with Enterobacteriaceae, Haemophilus influenzae, Pseudomonas aeruginosa, and gram-positive bacteria. Overall, ceftriaxone was equal or superior to cefotaxime and cefoperazone against systemic infections. All three drugs were highly potent against most organisms but were considerably less active against P.