Determination of antimicrobial susceptibility patterns of Nocardia spp. from clinical specimens by Etest

Abstract

Susceptibilities to 11 antimicrobial agents were determined by Etest for 93 Nocardia isolates from clinical specimens and 15 type strains belonging to different Nocardia spp. All isolates were susceptible to trimethoprim-sulphamethoxazole, amikacin and linezolid, but susceptibilities of the various Nocardia spp. to beta-lactams, aminoglycosides, ciprofloxacin and clarithromycin varied markedly. Overall, there was a good correlation between the drug resistance patterns and the species identification established by conventional phenotypic tests and 16S rDNA sequencing. Among the different species encountered, Nocardia farcinica and Nocardia brasiliensis displayed the most multiresistant profiles, with resistance to imipenem occurring mainly among isolates of N. brasiliensis and Nocardia abscessus. The species variability in susceptibility profiles and the numerous recent taxonomic changes means that in-vitro susceptibility tests may be a complementary tool for the identification of Nocardia isolates from human clinical specimens. Further studies on a larger number of species from more diverse geographical sources, including species that are found less commonly among clinical isolates, are required to validate and extend the results.

Nocardiosis: an overview and additional report of 28 cases in cattle and dogs

“…Usually nocardial therapy involves prolonged use of antimicrobials combined with surgical debridation/drainage, extirpation of foreign bodies and lavage of infected lesions using anti-septic solutions 2,10,19,25,26,30 . Long-term antimicrobial therapy is recommended due to intracellular localization of agent, development of pyogranulomatous inflammatory reaction and resistant pattern strains that lead to poor response to the conventional antimicrobial treatment 10,19,32 .…”

“…organisms show large variation in susceptibility in vitro to different antimicrobials. Sulfonamides-trimethoprim, amikacin and cephalosporins commonly show efficacy in human 3,25 and animal strains 26,45 . Antimicrobial susceptibility tested in 28 Nocardia strains in this trial showed that amikacin, ceftiophur, sulphamethoxazoletrimethoprim and gentamicin were the most-effective drugs.…”

“…These results are in agreement with other authors that have indicated sulfonamides combined with trimethoprim, aminoglycosides and cephalosporins as drugs of choice in nocardial therapy in domestic animals 2,26,27,32,37,39,45 . However, these results should be interpreted with care because in vitro susceptibility do not predict necessarily in vivo success in nocardial therapy 25,39 .…”

“…Nocardia spp. strains resistant to beta-lactam group and derivates, fluoroquinolones, macrolides and aminoglycosides have been reported 25,26 . The 28 Nocardia strains isolated from cattle and dogs in this trial show multiple drug resistance especially using beta-lactam group and derivates.…”

Species Spectrum of <I>Nocardia</I> spp. Isolated from Suspected Tuberculosis Patients

“…In current study, seven isolates identified as N. farcinica as first report of infections caused by this species from Iran. It has been reported to constitute 23.8%, 26.7%, 35.4% 44%, 60.3% and 33.3% and 21.6% of Nocardia isolates in France [14], Japan [28], Thailand [29], Belgium [30] [31], Germany [32] and Spain [16] respectively. Six of the clinical isolates were identified as N. wallacae as the first report of infections caused by the later species in Iran.…”