[Bacteria isolated from surgical infections and their susceptibilities to antimicrobial agents. Special references to bacteria isolated between April 1999 and March 2000].

The annual multicenter studies on isolated bacteria from infections in general surgery and their antimicrobial susceptibility have been conducted in Japan since July 1982. In this paper, the results obtained in the academic year 1999 (from April 1999 to March 2000) have been summarized. Two hundred seven cases were investigated, and 411 strains were isolated from 169 cases (81.6%). Of those strains, 184 and 227 strains were from primary infections and postoperative infections, respectively. In primary infections, the isolation rates of anaerobes, Streptococcus spp., and Escherichia coli were higher than in postoperative infections, while in postoperative infections, those of Gram-positive aerobes were higher than in primary infections. Staphylococcus aureus were most frequently isolated among Gram-positive aerobes, Peptostreptococcus prevotii among Gram-positive anaerobes, E. coli among Gram-negative aerobes, and Bacteroides fragilis among Gram-negative anaerobes. In primary infections, the percentage of Gram-negative aerobes, which gradually increased by the year 1998, decreased in the year 1999. The percentage of Gram-negative anaerobes increased, while that of Gram-negative bacteria was equivalent to that in the last year. In postoperative infections, the percentage of Gram-negative anaerobes, which continuously increased after the year 1990, decreased, while that of Gram-positive aerobes, which decreased in the last year, increased. Methicillin-resistant S. aureus accounted for 70.7% of S. aureus (41 strains). Either the number of strain or the percentage of MRSA decreased. The susceptibilities of E. coli and Klebsiella pneumoniae decreased against third and forth generation cephems, oxacephems, and monobactams. The susceptibilities of P. aeruginosa to carbapenems tend to decrease after the year 1997. S. aureus showed good susceptibilities to the tested drugs including arbekacin, vancomycin, and teicoplanin.