Susceptibility profiles of Nocardia spp. to antimicrobial and antituberculotic agents detected by a microplate Alamar Blue assay

Abstract

Nocardia species are ubiquitous in natural environments and can cause nocardiosis. Trimethoprim-sulfamethoxazole has long been the monotherapy treatment of choice, but resistance to this treatment has recently emerged. In this study, we used microplate Alamar Blue assays to determine the antimicrobial susceptibility patterns of 65 standard Nocardia isolates, including 28 type strains and 20 clinical Nocardia isolates, to 32 antimicrobial agents, including 13 little studied drugs. Susceptibility to the most commonly used drug, trimethoprim-sulfamethoxazole, was observed in 98% of the isolates. Linezolid, meropenem, and amikacin were also highly effective, with 98%, 95%, and 90% susceptibility, respectively, among the isolates. The isolates showed a high percentage of resistance or nonsusceptibility to isoniazid, rifampicin, and ethambutol. For the remaining antimicrobials, resistance was species-specific among isolates and was observed in traditional drug pattern types. In addition, the antimicrobial susceptibility profiles of a variety of rarely encountered standard Nocardia species are reported, as are the results for rarely reported clinical antibiotics. We also provide a timely update of antimicrobial susceptibility patterns that includes three new drug pattern types. The data from this study provide information on antimicrobial activity against specific Nocardia species and yield important clues for the optimization of species-specific Nocardia therapies.

Pyogranulomatous pleuropneumonia caused by Nocardia asiatica in a dog coinfected with canine morbillivirus (canine distemper virus)

“…The drug of choice used in the initial treatment of the dog described in this report was amoxicillin plus potassium clavulanate, which can be used as a monotherapy, or in combination (Sykes, ). However, retrospective studies on the susceptibility profiles indicated that Nocardia strains presented poor to intermediate sensitivity for amoxicillin plus potassium clavulanate (Ribeiro et al, ; Zhao et al, ), which could be associated with unsuccessful of therapy, leading to the death of the dog. Despite the approach of antimicrobial therapy, the death of the dog reported here reinforces the poor prognosis of generalized canine nocardiosis, especially in CM‐induced coinfections (Ribeiro, ; Ribeiro et al, ; Sykes, ).…”

“…Despite the approach of antimicrobial therapy, the death of the dog reported here reinforces the poor prognosis of generalized canine nocardiosis, especially in CM‐induced coinfections (Ribeiro, ; Ribeiro et al, ; Sykes, ). To date, the most in vitro effective antimicrobials against Nocardia spp., including N. asiatica , is represented by amikacin, ceftiofur, ceftriaxone, gentamicin, imipenem and sulfamethoxazole/trimethoprim (Ribeiro et al, ; Zhao et al, ).…”

“…The sequence of Mycobacterium fortuitum was included as an outgroup 2010; Ribeiro et al, 2008;Sykes, 2012). To date, the most in vitro effective antimicrobials against Nocardia spp., including N. asiatica, is represented by amikacin, ceftiofur, ceftriaxone, gentamicin, imipenem and sulfamethoxazole/trimethoprim (Ribeiro et al, 2008;Zhao et al, 2017).…”

Pathogenic Nocardia: A diverse genus of emerging pathogens or just poorly recognized?

“…Virulence and antimicrobial susceptibilities of various pathogenic Nocardia species vastly differ from one another. The most recent classification distributes the clinically relevant Nocardia species into 13 antimicrobial susceptibility patterns [29]. Nocardia farcinica tends to be a more virulent species, intrinsically resistant to various antibiotics, including third-generation cephalosporins [18].…”

Newer therapeutic modalities for Actinomycetoma by Nocardia species

“…Although molecular identification is not possible in all centers in resource‐poor countries, we believe that the sensitivity patterns, unlike dermatophytes, do not change dramatically between the species. A recent study (Pan Zhao et al) determined the antimicrobial susceptibility patterns of 65 standard Nocardia isolates, including 28 type strains and 20 clinical Nocardia isolates, to 32 antimicrobial agents, including 13 little studied drugs . The results show that SXT, meropenem, imipenem, linezolid, and amikacin are the most active antimicrobial agents against Nocardia strains, while most Nocardia isolates are highly resistant to isoniazid (Table ).…”