Perfil de sensibilidade antimicrobiana de Clostridioides (Clostridium) difficile ao metronidazol, vancomicina e moxifloxacina isolados de animais e seres humanos em Minas Gerais, Brasil

Abstract

Clostridioides difficile is a bacterial enteropathogen that infects animals and humans, able to promote intestinal disorders that can lead to its host's death. Infection with C. difficile (CDI) currently represents one of the main causes of nosocomial infection, with antibiotic therapy being the main predisposing factor. In the 2000s, outbreaks caused by C. difficile were closely related to the indiscriminate use of antibiotics of the fluoroquinolone class. In Brazil, the treatment of CDI is based on the use of metronidazole and vancomycin. The use of antimicrobials seems to have a direct relationship with the selection of certain strains of C. difficile. In this perspective, epidemiological studies related to the antimicrobial resistance of this pathogen are essential to avoid the emergence of strains that may represent a public health problem. However, the “gold standard” antimicrobial susceptibility test recommended for C. difficile is laborious and expensive. Thus, the diffusion disk test becomes a more attractive option, since the method is simple to perform, cheaper and more effective. The study aimed to evaluate the sensitivity profile to metronidazole, vancomycin and moxifloxacin using the disk diffusion method from 120 strains of C. difficile from animals and humans isolated in Brazil. According to cutoff points already established in previous studies, strains considered resistant in this test were submitted to the E-test method to confirm the phenotype through the minimum inhibitory concentration (MIC), according to the criteria recommended by the reference institution. In addition, three isolates classified as resistant to moxifloxacin were sequenced (gyrA gene) to detect mutations that could indicate the genotypic mechanism of drug resistance. There was no vancomycin-resistant isolate and one strain (0.8%), non toxigenic (RT010, clade 1), was resistant to metronidazole (MIC > 256 µg/mL). Regarding moxifloxacin, 14% (n = 17) of the strains evaluated were resistant, which obtained MIC > 32 µg/mL. The ribotype RT126 (clade 5) was the only one to present a positive statistical association of resistance to moxifloxacin (P < 0.0001), as well as isolates of the equine and swine species (P = 0.0139 and P = 0.0228, respectively). The Thr82Ile mutation was found in the three sequenced isolates. The study revealed a low frequency of resistance to metronidazole and vancomycin, while resistance to moxifloxacin was superior to previous studies carried out in Brazil.