Role of imipenem/cilastatin in the treatment of soft tissue infections.

Imipenem/cilastatin was given to 243 evaluable patients with moderately severe to severe soft tissue infections. Cultures prior to therapy yielded Staphylococcus aureus (108 isolates), group D and non-group D enterococci (49), group A streptococci (42), other aerobic gram-positive cocci (72), Pseudomonas aeruginosa (54), Escherichia coli (32), Proteus mirabilis (31), Enterobacter (21), Klebsiella (20), other aerobic gram-negative rods (58), Bacteroides fragilis group (16), and other anaerobes (65). Overall, 95 percent (230 of 243) of the patients treated had clinical cure (137 of 243) or improvement (93 of 243). Of the 506 strains of etiologic bacterial pathogens isolated from these patients and tested against imipenem, 498 (98 percent) were susceptible to the antibiotic. Many were resistant to both older and newer penicillins and cephalosporins. Serial cultures of infection sites revealed that 426 of 498 (86 percent) of pre-therapy bacterial isolates were eradicated by imipenem/cilastatin therapy. Eight of 498 etiologic pathogens (1.6 percent) acquired resistance to imipenem (seven P. aeruginosa and one enterococcus). Such resistance acquisition was associated with clinical failure in two patients. Imipenem/cilastatin appears to be a highly effective, relatively safe therapy of soft tissue infections caused by a wide variety of gram-positive and gram-negative aerobes and anaerobes, both polymicrobial and monomicrobial in nature. Imipenem/cilastatin should be considered particularly when infection by the more antibiotic-resistant of these bacteria is suspected or proved.