Minimum inhibitory concentration of Brazilian Brachyspira hyodysenteriae strains

Abstract

The objectives of this study were to characterize Brachyspira hyodysenteriae isolates and to evaluate the antimicrobial susceptibility patterns of strains obtained from pigs in Brazil based on the minimal inhibitory concentration test (MIC). The MIC was performed for 22 B. hyodysenteriae isolates obtained from 2011 to 2013 using the following antimicrobial drugs: tylosin, tiamulin, valnemulin, doxycycline, lincomycin and tylvalosin. Outbreaks of swine dysentery were diagnosed based on clinical presentation, bacterial isolation, gross and microscopic lesions, duplex PCR for B. hyodysenteriae and B. pilosicoli and nox gene sequencing. All obtained MIC values were consistently higher or equal to the microbiological cut-off described in the literature. The MIC 90 values for the tested drugs were 8μg/ml for doxycycline, >4μg/ml for valnemulin, 8μg/ml for tiamulin, 32μg/ml for tylvalosin, >64μg/ml for lincomycin and >128μg/ml for tylosin. These results largely corroborate those reported in the literature. Tiamulin, doxycycline and tylvalosin showed the lowest MIC results. All of the samples subjected to phylogenetic analysis based on the nox gene sequence exhibited similar results, showing 100% identity to B. hyodysenteriae. This is the first study describing the MIC pattern of B. hyodysenteriae isolated in Brazil.

Infectious diseases dynamics in growing/finishing pigs in Southern Brazil (2005-2016)

“…Strains of Brachyspira spp. resistant to commonly used antimicrobials have been detected in several studies (Duinhof et al 2008, Pringle et al 2012, and, recently, in Brazil in a investigation that evaluated the sensitivity of Brachyspira hyodysenteriae and Brachyspira pilosicoli to different classes of antimicrobials (Daniel et al 2017). Brachyspira species may survive in organic material, such as feces diluted in water, for as long as 48 days in environmental temperatures ranging from 0 to 10°C (Hampson & Burrough 2019); however, this study has detected a higher incidence of clinical disease during spring/summer, which may have occurred because of a higher infection pressure, as well as due to problems of bay drainage and asymptomatic pigs acting as carriers and infection sources (Hampson & Burrough 2019).…”

“…Two possible explanations may be applied to this increase in number of cases of Brachyspira spp. colitis: it may be related to a bacterial resistance to some of the antimicrobials commonly applied to control clinical disease; or it may have occurred due to the introduction of clinically health females, which could have carried subclinical infections to many sow farms of different integration companies (Daniel et al 2013, Daniel et al 2017. Strains of Brachyspira spp.…”

Antimicrobial susceptibility of U.S. porcine Brachyspira isolates and genetic diversity of B. hyodysenteriae by multilocus sequence typing

“…When comparing the antimicrobial susceptibility profiles of U.S B. hyodysenteriae isolates to those reported internationally, our findings suggest that, overall, U.S B. hyodysenteriae isolates are more susceptible to antimicrobials. Mainly, the U.S. B. hyodysenteriae isolates are more susceptible to tiamulin than the isolates from the United Kingdom, 17 Italy, 31 Poland, 38 Germany, 13,17 the Czech Republic, 32 Brazil, 6 Japan, 16 and Spain. 12 However, it is worth noting that, in Europe, there are limited antimicrobials available for the treatment of SD.…”

Identification and distribution of Brachyspira species in feces from finishing pigs in Argentina

“…In Latin America, limited studies were carried out concerning the presence of different species of Brachyspira. In Brazil, some regional studies identified B. hyodysenteriae and B. pilosicoli in pigs [11,12]. In Mexico, strongly and weakly hemolytic spirochetes were identified in 22% of pig farms [13].…”