In vitro susceptibility of clinical isolates ofBacteroides fragilis andBacteroides thetaiotaomicron in Japan

Abstract

A nationwide survey of the susceptibility of 433 isolates of Bacteroides fragilis and 149 isolates of Bacteroides thetaiotaomicron was conducted from December 1986 through November 1989 in Japan. These strains were collected from 16 university hospitals and one metropolitan hospital. Metronidazole was the most active drug against both species, with no resistant isolates found. The activity of imipenem and sulbactam-cefoperazone was good, with very low resistance rates determined in Bacteroides fragilis (1.4% and 1.6%, respectively) and in Bacteroides thetaiotaomicron (3.4% for both drugs), and was comparable to that of metronidazole. Cefoxitin, cefmetazole, cefotetan, cefbuperazone, latamoxef and ceftizoxime were found to be more active against Bacteroides fragilis, for which resistance rates were 3.2 to 9.5%, than against Bacteroides thetaiotaomicron, for which resistance rates were 18.1 to 21.8%. Rates of piperacillin resistance in the two species were 12.9% and 26.8%, respectively. Clindamycin was very active at a low concentration (MIC50 of 0.39 to 1.56 mg/l), but 24% and 27.5% of Bacteroides fragilis and Bacteroides thetaiotaomicron isolates, respectively, were resistant to this agent.

Activity of β-lactam antimicrobial agents against clinical isolates of Bacteroides fragilis in Kuwait

“…Eighteen (8%) of the 221 isolates were resistant (MIC 16 mg/L) to amoxycillin/clavulanic acid. Our findings confirm previous reports, particularly from Japan and the USA, of the susceptibility of B. fragilis to this agent [7,10]. It is possible that a β‐lactamase that is not inhibited by clavulanic acid, as has been described previously in B. fragilis homology group II [10], may be present in these strains.…”

“…The results also show that piperacillin/tazobactam was more active than piperacillin when tested alone; piperacillin was only active against 62% of the isolates. The superior activity of piperacillin/tazobactam against B. fragilis has also been reported elsewhere [7,11]. Although not measured in this study, it is possible that the high MIC 90 of piperacillin may be due to hyperproduction of β‐lactamase [10].…”

“…Data generated from various nationwide surveillance studies of the susceptibility of B. fragilis to a variety of antibiotics in the USA [3,4], Europe [5,6] and Japan [7] have been published. So far, surveys of antibiotic susceptibility of B. fragilis have not been conducted in Kuwait.…”

A five-year multicenter study of the susceptibility of the Bacteroides fragilis group isolates to cephalosporins, cephamins, penicillins, clindamycin, and metronidazole in the United States

“…Our higher rates of clindamycin resistance more closely agree with reports from Spain and France (Dubreuil et al, 1992;Reig et al, 1984;Garcia-Rodriquez and Garcia-Sanchez, 1985). In Japan, a report by Watanabe et al (1992) described susceptibility patterns of B. fragilis and B. thetaiotaomicron strains. Resistance to imipenem was found among both groups of isolates, with resistance rates of 1.6% and 3.4%, respectively.…”

Antimicrobial Resistance in Anaerobes

“…Imipenem remains the most potent /3-lactam agent. It is notable that Australia is the one country in which MICs of the 0-lactam agents are consistently lower than those in the United States for non fragilis Bacteroides isolates.Clindamycin and metronidazole are both quite active against the B. fragilis group, although a frequency of resistance to clindamycin of up to 25% has been reported in localized areas such as southern Europe and Japan [6,12,15]. Susceptibility patterns for other anaerobes including fusobacteria, clostridia, and propionibacteria are quite different as the penicillins have retained potent activity.…”