Comparative in vitro activities of nemonoxacin, doripenem, tigecycline and 16 other antimicrobials against Nocardia brasiliensis, Nocardia asteroides and unusual Nocardia species.
OBJECTIVE
The aim of this study was to assess the in vitro activities of nemonoxacin (a novel non-fluorinated quinolone), doripenem, tigecycline and 16 other antimicrobial agents against the Nocardia species.


METHODS
MICs of 19 antimicrobial agents for 125 clinical isolates of the Nocardia species were determined by the broth microdilution method.


RESULTS
Nocardia brasiliensis (n = 61), Nocardia asteroides (n = 45), Nocardia flavorosea (n = 5), Nocardia otitidiscaviarum (n = 4), Nocardia farcinica (n = 3), Nocardia beijingensis (n = 2), Nocardia puris (n = 2) and one each of Nocardia nova, Nocardia jinanensis and Nocardia takedensis were identified based on a 16S rRNA gene sequencing analysis. For N. brasiliensis isolates, the MIC(90)s of the tested quinolones were in the order nemonoxacin < gemifloxacin = moxifloxacin < levofloxacin = ciprofloxacin, and the MIC(90)s of the tested carbapenems were in the order doripenem = meropenem < ertapenem < imipenem. Tigecycline had a lower MIC(90) (1 mg/L) than linezolid (8 mg/L). For N. asteroides isolates, the MIC(90)s of the tested quinolones were in the order nemonoxacin < gemifloxacin = moxifloxacin < levofloxacin < ciprofloxacin, and the MIC(90)s of the tested carbapenems were in the order doripenem = meropenem = imipenem < ertapenem. For the other 19 Nocardia species isolates, nemonoxacin showed good activity with the lowest MIC(90) of the tested quinolones. Among the four tested carbapenems, doripenem and meropenem had comparatively lower MIC(90)s.


CONCLUSIONS
The results of this in vitro study suggest that nemonoxacin, linezolid and tigecycline show promise as treatment options for nocardiosis. Further investigation of their clinical role is warranted.
Lai
Chih-Cheng
CC
Department of Internal Medicine, Yi-Min Hospital, Taipei, Taiwan.
Tan
Che-Kim
CK
Lin
Sheng Hsiang
SH
Liao
Chun-Hsing
CH
Chou
Chien-Hong
CH
Hsu
Hsiao-Leng
HL
Huang
Yu-Tsung
YT
Hsueh
Po-Ren
PR
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D006801:Humans; D008826:Microbial Sensitivity Tests; D009615:Nocardia / Q000145:classification / Q000187:drug effects* / Q000302:isolation & purification; D009617:Nocardia Infections / Q000382:microbiology; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA
D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D012336:RNA, Ribosomal, 16S