Role of Enterotoxin-Producing Staphylococci in Zoonotic Infections in Iran

Abstract

Context Typical opportunistic pathogens of coagulase positive Staphylococcus spp. are capable of causing a wide spectrum of different purulent and toxin-mediated diseases such as enteric infections. 1 Staphylococcus intermedius is very similar to S. aureus in phenotypic characteristics and similarly produces enterotoxins. 2-4 Pigment production, hemolysis, alkaline phosphatase and urease positive tests, mannitol and maltose fermentation and susceptibility to novobiocin and Polymyxin B are characteristics of S. intermedius. 2,5 Originally regarded as a single species, molecular characterization has placed S. intermedius in a new classification as S. intermedius group (SIG), which includes S. intermedius, S. pseudintermedius, and S. delphini. 6,7 These species cause diseases in human and animals (especially people who keep pets at home). S. aureus is a human commensal, while other coagulase positive species are present in animals. It has been revealed that S. intermedius mostly infects dogs (resides on the skin or mucosal surfaces). 8 The general transferability of these species between pets and humans has increased during recent years. 9,10 Staphylococcal species are able to express a wide spectrum of virulence factors, such as coagulase, cell wall components, hemolysins, proteases, enterotoxins, toxic-shock syndrome (TSS), and exfoliating toxins. 11 Enterotoxins produced by these species are pyrogenic components not inactivated by gastrointestinal enzymes and thermal process and lead to diarrhea. Enterotoxins are members of superantigens and more than 20 different types have been recognized, however some most important agents include SEA, SEB, SEC, SED and SEE. 12,13 On the other hand, increasing antibiotic resistance among coagulase positive staphylococci is an ongoing concern. 14 Differentiation of coagulase positive staphylococci except for S. aureus by phenotypic tests is a difficult and unreliable or insufficient process in laboratory settings. 15 Considering this, several methods have been introduced for the identification of these strains, 16 for example a molecular test including hsp60 and sodA genes could differentiate them. 17 S. intermedius is the predominant infectious agent among non-S. aureus coagulase positive species in Iran according to previous reports. The aims