252. Multicentre survey of the antibiotic susceptibility of anaerobic gran-negative bacilli in Japan
Session: Poster Abstract Session: Diagnostic Microbiology; Antimicrobial Sensitivities
Thursday, October 3, 2013
Room: The Moscone Center: Poster Hall C
Background: Multicenter survey of thd antibiotic susceptibility of anaerobic gram-negative bacilli was conducted in Japan.

Methods: One hundred and forty-seven clinical anaerobic gram-negative anaerobic bacteria from patients were collected 14 centers at Hokuriku district in Japan in 2012. MICs were ditermined using microbroth dilution for the following antimicrobials: ampicillin-sulbactam (ABPC/SBT); piperacillin-tazobactam (PIPC/TAZ); cefmetazole; ceftriaxon; imipenem; meropenem; clindamycin; and metronidazole. CLSI guideline was used for interpretation.

Results: Bacteroides spp. (n=93), Prevotella spp. (n=41), Fusobacterium spp. (n=11), and Porphyromonas asaccharolytica (n=2) were collected from 14 centers. The most frequently isolated species among the Bacteroides spp. was B. fragilis (n=61, 41.5%), followed by B. thetaoitaomicron  (n=9, 6.1%), B. obatus (n=7, 4.8%). The most frequently isolated species among the Prevotella spp. was P. intermedia and P. melaninogenica (n=11, 7.5%, each). Susceptibility rates for these isolates were 98.0% imipenem and metronidazole, 95.9% meropenem, 95.2% PIPC/TAZ, 84.4% ABPC/SBT, 71.4% cefmetazole, 61.9% clindamycin, and 42.9% ceftriaxone. Only two B. fragilis and one F. necrophorum isolate showed resistant to carbapenems, and the F. necrophorum strain showed resitance to metronidazole but susceptible to penicillins. The other strain resistant to metronidazole was B. thetaiotaomicron, which showed reisistant to penicillins but susceptible to cefems and carbapenems. Non-susceptible rate to clindamycin was relatively higher among non-B. fragilis Bacteroides species (84.4%) than B. fragilis (36.0%) .

Conclusion: Carbapenems, PIPC/TAZ, and metronidazole were active against most clinically isolated anaerobic gram-negative bacilli. However, the emergence of resistance to these agents is a cause of concern especially in severe anaerobe infections and the periodic monitoring of the susceptibility of anaerobes to guide empirical treatment should be performed.

Yoshitsugu Iinuma, MD, PhD1, Hisashi Baba, MD, PhD1, Junichi Mitsuyama2 and Nobuhiko Nomura3, (1)Department of Infectious Diseases, Kanazawa Medical University, Uchinada, Japan, (2)Business Strategy Department, Toyama Chemical Co., Ltd., Tokyo, Japan, (3)Research Laboratories, Toyama Chemical Co., Ltd., Toyama, Japan


Y. Iinuma, None

H. Baba, None

J. Mitsuyama, None

N. Nomura, None

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