To ascertain the contribution of SXT to strain resistance profile, we analysed for the presence of sul2, floR, dfr18, strB, and dfrA1, typical clustered resistance genes, able to discriminate among SXT variant. Results revealed that some V. vulnificus, V. metschnikovii, V. fluvialis and V. parahaemolyticus contained one to six of the antibiotic resistance genes of SXT-like element (Additional file 1). The most abundant strain that harboured most of the antibiotic resistance genes and SXT element is V. fluvialis. Strains AL024, AL038, AL054 AL056 and AL009 lack SXT integrase, hence, the entire element. TMP, STR
and COT resistance can then be associated with any other CYT387 in vitro mobile element especially the class 1 integrons, already WZB117 clinical trial described in Africa, both in V. cholerae and V. parahaemolyticus. SXT-like element devoid of the resistance cluster could be represented by strain AL016, positive for the integrase but not for the gene cassettes. Table 2 Sequence of primers used for detection of antibiotics resistance genes and the SXT this website element. Primer Sequence (5′ to 3′) Target gene Amplicon size (bp) Reference SXT-F ATGGCGTTATCAGTTAGCTGGC SXT integrase 1035  SXT-R GCGAAGATCATGCATAGACC SUL2-F AGGGGGCAGATGTGATCGC sul2 625  SUL2-B TGTGCGGATGAAGTCAGCTCC
FLOR-F TTATCTCCCTGTCGTTCCAGCG floR 526  FLOR-2 CCTATGAGCACACGGGGAGC TMP-F TGGGTAAGACACTCGTCATGGG dfr18 389  TMP-B ACTGCCGTTTTCGATAATGTGG TetA-F GTA ATT CTG AGC ACT GTC GC TetA 950  TetA-R CTG CCT GGA CAA CAT TGC TT strB-F GGCACCCATAAGCGTACGCC strB 470  strB-R TGCCGAGCACGGCGACTACC dfr1-F CGAAGAATGGAGTTATCGGG
dfrA1 372  dfr1-B TGCTGGGGATTTCAGGAAAG To date, there have been no reports on the antibiotic resistance genes in V. vulnificus, V. metschnikovii, V. fluvialis and V. parahaemolyticus isolated from wastewater final effluents in rural communities of South Africa. The PCR result showed the presence and prevalence of SXT-like elements (with an amplicon size of 1035 bp) in the Vibrio strains (Additional file 1). The SXT-like element encodes different types of antibiotic resistance many genes, floR (526 bp), sul2 (625 bp), and strB (470 bp), which confer resistance to chloramphenicol (Chl), sulfamethoxazole (Sul), and streptomycin (Str), respectively (Additional file 1). Trimethoprim (Tmp) resistance genes were detected with the amplification of a 372 and 389 bp fragment of dfrA1 and dfr18 (Additional file 1). The molecular analysis of these genes has been previously carried out in V. cholerae O1 and O139 [18, 29]. In this present study, all strains exhibited multiple resistances to five antibiotics. Ramachandran et al.  carried a study of 51 strains of V.