Antimicrobial Susceptibility of Streptococcus suis Isolated from Diseased Pigs in Thailand, 2018–2020

Abstract

Streptococcus suis is a porcine and zoonotic pathogen that causes severe systemic infection in humans and pigs. The treatment of S. suis infection relies on antibiotics; however, antimicrobial resistance (AMR) is an urgent global problem, pushing research attention on the surveillance of antibiotic-resistant S. suis to the fore. This study investigated the antimicrobial susceptibility of 246 S. suis strains isolated from diseased pigs in Thailand from 2018–2020. The major sources of S. suis strains were lung and brain tissues. PCR-based serotyping demonstrated that the most abundant serotype was serotype 2 or ½, followed by serotypes 29, 8, 9, and 21. To the best of our knowledge, this is the first report describing the distribution of AMR S. suis serotype 29 in diseased pigs. The antimicrobial susceptibility test was performed to determine the minimum inhibitory concentrations of 35 antimicrobial agents. The results showed that important antimicrobial agents for human use, amoxicillin/clavulanic acid, daptomycin, ertapenem, meropenem, and vancomycin, were the most effective drugs. However, a slight decrease in the number of S. suis strains susceptible to amoxicillin/clavulanic acid and vancomycin raised awareness of the AMR problem in the future. The data indicated a tendency of reduced efficacy of available veterinary medicines, including ampicillin, cefepime, cefotaxime, ceftiofur, ceftriaxone, chloramphenicol, florfenicol, gentamicin, penicillin, and tiamulin, for the treatment of S. suis infection, thus emphasizing the importance of the prudent use of antibiotics. The widespread of multidrug-resistant S. suis strains was identified in all serotypes and from different time periods and different regions of the country, confirming the emergence of the AMR problem in the diseased pig-isolated S. suis population.

Characterization of integrative and conjugative elements carrying antibiotic resistance genes of Streptococcus suis isolated in China

“…Most of clinical S. suis strains remain sensitive to beta-lactams antibiotic, including penicillin and cephalosporin ( Hoa et al, 2011 ; Wang et al, 2019 ; Bamphensin et al, 2021 ). Resistance to penicillin in S. suis strains isolated from pigs is gradually increasing ( Zhang et al, 2008 ; Lunha et al, 2022 ). In the present study, S. suis strains YS162 and YS388 were resistance to penicillin with the minimum inhibitory concentration (MIC) value 6 μg/ml for each strain, meanwhile S. suis strain YS34 was resistant to amoxicillin with MIC value 64 μg/ml.…”

“…Integrative conjugative elements (ICEs), prophages and tandem ICE-prophages located at different insertion sites were common MGEs described in S. suis ( Uruen et al, 2022 ). Integrative and conjugative elements (ICEs) comprise the majority of MGEs and are critical contributors to the acquisition and distribution of AR genes in S. suis ( Huang et al, 2016a ), in which harbored tetracycline, macrolide, and lincomycin resistance genes ( Li et al, 2011 ; Palmieri et al, 2011b ; Marini et al, 2015 ; Athey et al, 2016 ; Huang et al, 2016a , b ; Zheng et al, 2018 ; Libante et al, 2019 ; Pan et al, 2019 ; Shang et al, 2019 ; Zhu et al, 2019 ; Dechene-Tempier et al, 2021 ; Lunha et al, 2022 ; Yang et al, 2022 ). On the contrary, tetracycline, macrolide, lincomycin, nucleoside, and aminoglycoside resistance genes associated tandem ICE-prophages and prophage were often reported in S. suis clinical strains ( Palmieri et al, 2011b ; Huang et al, 2016a ; Wang et al, 2019 ).…”

Resistance of Streptococcus suis Isolates from the Czech Republic during 2018–2022

“…The high frequencies of resistance to tetracycline correlate with the frequent use of this antibiotic for the treatment S. suis infections on pig farms [ 21 , 22 ]. Moreover, high levels of occurrence of resistance have also been described in protein synthesis inhibitors, such as tetracycline and clindamycin [ 4 , 23 , 24 ]. Resistance to tiamulin and macrolides (tilmicosin and tulathromycin) is reported very often in the antimicrobial susceptibility testing of Streptococcus spp.…”

“…According to published studies, the occurrence of individual serotypes in the monitored geographic areas varies, and often changes over time [ 24 ]. Serotype 2 was presented as predominant worldwide (in North America, Europe, and Asia) in recent years [ 4 , 39 , 40 , 41 ].…”

Theaflavin Ameliorates Streptococcus suis-Induced Infection In Vitro and In Vivo

“…In China, S. suis has previously received much attention on account of two large outbreaks of human infection in 1998 and 2005, resulting in at least 237 infections and 53 deaths [ 13 , 14 ]. There are 33 serotypes of S. suis based on a capsular polysaccharide, among which serotype two (SS2) is considered to be the most virulent and prevalent strain isolated from diseased pigs and human beings [ 15 , 16 ]. The traditional treatment of S. suis infection depends on antibiotics, just like other bacterial infections.…”