Antimicrobial susceptibility of animal and human isolates of Clostridium difficile by broth microdilution

Abstract

A total of 188 human (n592) and animal (n596) isolates of Clostridium difficile of different PCR ribotypes were screened for susceptibility to 30 antimicrobials using broth microdilution. When comparing the prevalence of antimicrobial resistance, the isolates of animal origin were significantly more often resistant to oxacillin, gentamicin and trimethoprim/sulfamethoxazole (P,0.01). The most significant difference between the animal and human populations (P50.0006) was found in the level of imipenem resistance, with a prevalence of 53.3 % in isolates of human origin and 28.1 % in isolates of animal origin. Overall, the results show similar MICs for the majority of tested antimicrobials for isolates from human and animal sources, which were collected from the same geographical region and in the same time interval. This supports the hypothesis that C. difficile could be transmissible between human and animal hosts. Resistant isolates have been found in all animal species tested, including food and companion animals, and also among non-toxigenic isolates. The isolates of the most prevalent PCR ribotype 014/020 had low resistance rates for moxifloxacin, erythromycin, rifampicin and daptomycin, but a high resistance rate for imipenem. Multiresistant strains were found in animals and humans, belonging to PCR ribotypes 012, 017, 027, 045, 046, 078 and 150, and also to non-toxigenic strains of PCR ribotypes 010 and SLO 080.

Antibiotic resistance patterns and PCR-ribotyping of Clostridium difficile strains isolated from swine and dogs in Italy

“…PCRribotype 014/020 and 012 were also detected in dogs with a percentage of 26% and 3%, respectively. However, the predominant type in dogs (64%) was the non-toxinogenic PCR-ribotype 010, as already observed in previous studies [6,38].…”

“…Among dogs, 51% (20/39) of strains was resistant to CLI, 46% (18/39) to ERY, 21% (8/39) to MTZ and 5% (2/39) to MXF or RIF. None canine strains showed resistance to VAN. A great variation in susceptibility to ERY and CLI has been observed in C. difficile animal strains [12,38,42]. In this study, the majority of porcine and canine strains were resistant to ERY and CLI, respectively.…”

“…In fact, typing of clinical isolates, voluntary sent to Istituto Superiore di Sanit a (ISS) from different Italian hospitals, indicates that only 5% of strains isolated in 2012e2013 were 078 (data not shown). PCR-ribotype 150 has been described only in animals [38], whereas PCR-ribotype 127 has been detected in both animals and humans [39,40]. PCR-ribotype 127, together with 078, 126, 033 and 237, belongs to clade 5 by multilocus sequence typing (MLST) and it is binary toxin-positive (as the other types of the clade) [40].…”

Strain Types and Antimicrobial Resistance Patterns of Clostridium difficile Isolates from the United States, 2011 to 2013

“…The ribotype 014/020 isolates in our study were typically susceptible to most antimicrobial agents, similar to data reported from European studies (17). The low levels of resistance of 014/ 020 strains (18) raise the question of what other factors are responsible for its increased frequency.…”

Investigation of Clostridium difficile interspecies relatedness using multilocus sequence typing, multilocus variable-number tandem-repeat analysis and antimicrobial susceptibility testing

“…In consequence, it may be useful to combine both methods (MLVA and MLST) in order to resolve phylogenetic diversity (Zaiss et al, 2009) although the best alternative could be whole genome sequencing, which is generally considered to be the next generation tool to type bacterial strains. Resistance of C. difficile to multiple antimicrobials has been described in several previous studies in both humans and animals (Pelaez et al, 2013;Pirs et al, 2013). Even though some isolates were resistant to both moxifloxacin and erythromycin or to clindamycin and erythromycin, no association between antimicrobial resistance and toxigenic isolates was observed in our study, echoing the results of previous work by Pituch et al (2005).…”