Clonal Complexes and Diversity of Exotoxin Gene Profiles in Methicillin-Resistant and Methicillin-Susceptible Staphylococcus aureus Isolates from Patients in a Spanish Hospital

Abstract

Molecular epidemiology studies have allowed the identification of the methicillin (meticillin)-resistant (MRSA) and methicillin-susceptible (MSSA) clonal complexes (CCs) and clones of, and CC59 were also detected. Many exotoxin genes were present in each of the 81 isolates, independent of whether they were involved in sepsis (11 to 22) or other types of infections (13 to 21), and they appeared in 73 combinations. The relevant data are that (i) all isolates were positive for hemolysin and leukotoxin genes (98.8% for lukED and 25.9% for lukPV); (ii) all contained an enterotoxin gene cluster (egc with or without seu), frequently with one or more genes encoding classical enterotoxins; (iii) about half were positive for tst and 95% were positive for exfoliatin-encoding genes (eta, etb, and/or etd); and (iv) the four agr groups were detected, with agrII (55.6%) and agrIII (23.5%) being the most frequent. Taken together, results of the present study suggest a frequent acquisition and/or loss of exotoxin genes, which may be mediated by efficient intralineage transfer of mobile genetic elements and exotoxin genes therein and by eventual breakage of interlineage barriers.Staphylococcus aureus is both a commensal bacterium and an extremely versatile pathogen that causes a wide range of diseases in humans, including superficial, deep-seated, and systemic infections, as well as a variety of toxemic syndromes, such as toxic shock syndrome (TSS), staphylococcal scaldedskin syndrome (SSSS), and staphylococcal food poisoning (36). S. aureus produces a wide range of virulence factors that mediate host colonization, invasion of damaged skin and mucosa, dissemination through the body, and evasion of host defense mechanisms (8,12). Relevant among them are a variety of exotoxins that comprise ␣-, ␤-, ␥-, and ␦-hemolysins, leukotoxins (the classical LukS-PV-LukF-PV Panton-Valentine leukocidin [LukPV], LukE-LukD [LukED] and LukM-LukFЈ-PV [LukM]), exfoliative toxins, and pyrogenic toxin superantigens, such as the staphylococcal TSS toxin (TSST-1, first referred to as SEF) and staphylococcal enterotoxins (SEs) (14,29,43). Five major serological types of SEs, SEA through SEE (known as classical enterotoxins, encoded by the sea to see genes, respectively) have been initially identified. However, new types of SEs and their coding genes (seg through seu) were later reported. Several SE genes (seg, sei, sem, sen, and seo) are part of an operon termed the enterotoxin gene cluster (egc

Genotypes, Exotoxin Gene Content, and Antimicrobial Resistance of Staphylococcus aureus Strains Recovered from Foods and Food Handlers

“…As in S. aureus strains from other sources, the frequency of resistance to ampicillin-penicillin was high (61.3%) in the foodrelated isolates tested in this study, and the responsible gene, blaZ, was often associated with Tn552 (23). The frequency of resistance to other antimicrobial agents, including oxacillin (methicillin) (6.5%), erythromycin (25.8%), clindamycin (19.4%), and gentamicin-tobramycin (6.5%), was lower than that reported in Spanish hospitals (2,4,14). This is in agreement with data from Kér-ouanton et al (25), showing that strains from SFP outbreaks were more susceptible to antimicrobials than human clinical isolates.…”

Population structure and exotoxin gene content of methicillin-susceptible Staphylococcus aureus from Spanish healthy carriers

“…Substantial [9,39,40]. In addition, spatypes within each CC were closely related, and accurately predicted the experimentally determined STs.…”

“…It is of note that identical PFGE-types were shown by MSSA from healthy carriers in the community and MSSA from clinical samples in the HUCA [9]. These included S5, S31, S33, S26, S127, S129 within the CC5, CC30, CC45 and CC59 clonal complexes (Figs.…”

Virulence and Resistance Determinants of German Staphylococcus aureus ST398 Isolates from Nonhuman Sources

“…Positive controls for PCR amplification analyses were taken from previously analyzed collections (2) or were provided by the European Community Reference Laboratory for Antimicrobial Resistance (EURL-AR, Food-DTU, Copenhagen, Denmark) and the German National Reference Centre for Staphylococcus (NRZ-Staph, Robert Koch Institute [RKI], Wernigerode, Germany).…”