Antimicrobial resistance phenotypes and genotypes of Streptococcus suis isolated from clinically healthy pigs from 2017 to 2019 in Jiangxi Province, China

Abstract

Aims This study aimed to investigate the antimicrobial resistance (AMR) profiles and genotypes of Streptococcus suis from Jiangxi Province, China. Methods and Results A total of 314 nasal swab samples were collected from clinically healthy pigs, with a positive isolation rate of S. suis of 34·08%. Antimicrobial susceptibility testing showed that more than 80% of the isolates were susceptible to vancomycin, penicillin, minocycline and chloramphenicol. A high frequency of resistance to clindamycin, tetracycline, clarithromycin and erythromycin was observed. All of the isolates were resistant to three or more categories of antimicrobials. The erm(B) and tet(O) served as the most frequent genotypes that contributed to lincosamide, macrolide and tetracycline resistances. A part of macrolide‐resistant genotypes could not exhibit specific phenotypes. Finally, integrative and conjugative elements (ICEs) were identified in 28·97% of the isolates. Conclusions The multidrug resistance of S. suis has widely emerged in Jiangxi Province. The most prevalent resistance genes and genotypes were similar to those in other regions or countries. The presence of ICEs is increasing the risk of horizontal transfer of AMR genes. Significance and Impact of the Study The findings could provide guidance for the rational use of antimicrobial drugs and be helpful for monitoring the AMR information of S. suis in China.

Non-serotype 2 isolates from healthy pigs are a potential zoonotic reservoir ofStreptococcus suisgenetic diversity and antimicrobial resistance

“…More than 80% of isolates contained at least one gene predicted to confer macrolide resistance (Palmieri et al, 2011). The presence of erm ( B ) and mef ( A ) genes are consistent with previous studies, where erm ( B ) is strongly linked with macrolide-lincosamide-streptogramin B (MLS B ) resistance and presented in 59-90% of macrolide-resistant S. suis isolates from pigs (Martel et al, 2001; Zhang et al, 2015; Tan et al, 2020). The resistant gene, erm ( T ) has been detected in S. agalactiae, S. pyogenes , and other erythromycin-resistant isolates of group D Streptococci (Chen et al, 2012; Zhang et al, 2015; Yongkiettrakul et al, 2019), our identification of erm ( T ) in this study suggests potential within-genus HGT.…”

“…In addition, we detected tet( L ) and tet ( W ) genes, which have not often been reported in S. suis , among non-serotype 2 isolates from healthy pigs. Corresponding phenotypic resistance to tetracycline was reported in over 90% of isolates, which is consistent with global data reporting widespread resistance to tetracycline and macrolides, likely related to the prophylactic use in agriculture (Soares et al, 2014; Yongkiettrakul et al, 2019; Mourkas et al, 2020; Tan et al, 2020). AMR may play a role in increasing numbers of treatment failures (Hughes et al, 2009; Gurung et al, 2015; Yongkiettrakul et al, 2019), and in our study, despite widespread MDR, we observed phenotypic susceptibility to all three of the recommended antimicrobials used to treat clinical S. suis meningitis (penicillin, ceftiofur, and ceftriaxone) (van Samkar et al, 2015; Seitz et al, 2016).…”

Update on the Mechanisms of Antibiotic Resistance and the Mobile Resistome in the Emerging Zoonotic Pathogen Streptococcus suis

“…Two mechanisms of resistance to tetracyclines have been characterized in S. suis: (i) efflux pumps that expel the antibiotic outside the cell and are encoded either by tet (L), tet (B), tet (K), or tet (40) genes [ 19 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 ] and (ii) ribosome protection proteins, encoded by tet (O) (the most frequently described gene in S. suis ), tet (M), tet (S), tet (W), tet (O/W/32/O), or tet (O/32/O) genes [ 18 , 21 , 23 , 24 , 25 , 26 , 30 , 32 , 33 ] ( Figure 1 ).…”

Strain Characterization of Streptococcus suis Serotypes 28 and 31, Which Harbor the Resistance Genes optrA and ant(6)-Ia

“…The erm(B) gene is present in a variety of Gram-positive bacteria, including enterococci, streptococci, and staphylococci [35]. AR gene erm (B) served as the most frequent genotype that contributed to macrolide resistances [36]. In our study, strains 11313 and 11LB5 carry erm (B) gene and appear to be highly resistant to macrolide antibiotics spiramycin.…”