Detection of Methicillin-Susceptible Staphylococcus aureus ST398 and ST133 Strains in Gut Microbiota of Healthy Humans in Spain

Abstract

Fecal samples of 100 healthy humans were tested for Staphylococcus aureus recovery. Fifteen samples (15 %) contained S. aureus, all methicillin-susceptible (MSSA), being one isolate/sample further studied. These 15 isolates were characterized by spa and agr typing as well as multi-locus sequence typing. High diversity of spa types (n = 11) and sequences types (n = 8) was detected. Two S. aureus of lineages ST398 or ST133 were detected, and six isolates were ascribed to clonal complex 30 (CC30). Strains were susceptible to most of the 17 antimicrobial agents tested with exceptions: erythromycin/clindamycin (three strains, containing erm(C) and/or erm(A) + mph(C) genes) and tobramycin and mupirocin (one strain containing ant(4')-Ia + mup(A) genes). The presence of 18 staphylococcal enterotoxin genes was studied by PCR, and isolates were negative for lukF/lukS-PV genes, although strain ST133 harbored the lukD-lukE + lukM genes. Other virulence genes detected were (number of strains): tsst-1 (6), hla (15), hlb (9), hld (15), hlg (6), hlgv (9), cna (2), aur (14), and egc-like cluster (3). Analysis of immune evasion cluster genes showed six types, highlighting their absence in two strains of lineages ST133 and ST5. A high clonal diversity of MSSA strains was identified in the intestinal microbiota of healthy humans, being CC30 the most frequent one. This is the first report of MSSA ST133 and ST398 isolates in gut microbiota of healthy humans.

Molecular characterization of Staphylococcus aureus isolated from humans related to a livestock farm in Spain, with detection of MRSA-CC130 carrying mecC gene: A zoonotic case?

“…This genetic lineage has been previously reported in canine samples from Japan 29 and the absence of the genes of IEC system points to a possible animal origin of the strain. 13 In the same line, detection of one MSSA strain typed as t2678-ST133-CC133 is remarkable because in previous studies it has been detected in small ruminants such as goats or sheep. 30 The detection of gene lukM, prevalent in ungulates, ruminants and bovine mastitis, 7 and the absence of IEC genes, supports the idea of the possible animal origin of the strain.…”

“…Seven of the spa types identified in this study were ascribed to CC30, a lineage frequently found as colonizer of human microbiota, 13,27 and it is also considered one of the most frequent S. aureus lineages detected in human infections. 3 Strains of skin origin of lineage CC30, recovered from the individual of case 4, harbored the tsst-1 gene encoding the toxic shock syndrome toxin (TSST).…”

“…Identification of S. aureus and MRSA was performed by conventional methods (DNAse assay, catalase and Gram staining) and confirmed by specific PCRs of the nuc (S. aureus specific thermonuclease) and mecA or mecC genes. 13,14 S. aureus isolates were typed by: spa (www.ridom.com), agr, and multilocus sequence typing (MLST) (saureus.mlst.net). 11 spa-and agr-typing were performed for all S. aureus isolates.…”

The staphylococcal alpha-toxin and leukotoxins

“…It is also active on some human leukocytes at higher concentrations than for other leukotoxins and α-toxin. These observations may raise questions about the role of this toxin into the bacterial pathogeny [151][152][153][154].…”

Correlation Between Serum 25‐Hydroxyvitamin D and Virulence Genes of Staphylococcus aureus Isolates Colonizing Children with Atopic Dermatitis

“…Seventeen virulence genes were analyzed using polymerase chain reaction (PCR) in recovered S. aureus isolates (16). The genes and the encoded virulence factors tested were Panton-Valentine leukocidin (lukF/lukS-PV); toxic shock syndrome toxin (tsst-1); exfoliative toxins A, B, and D (eta, etb, etd, respectively); alpha-, beta-, delta-, gamma-, and gamma-hemolysin variant (hla, hlb, hld, hlg and hlgv, respectively); leukocidins DE and M (luk-DE and lukM, respectively); aureolysin (aur); biofilm-associated protein (bap); adhesion factor (cna); and enterotoxin B and C (seb and sec, respectively).…”