A study of the enterotoxigenicity of coagulase-negative and coagulase-positive staphylococcal isolates from food poisoning outbreaks in Minas Gerais, Brazil

• Published in: International journal of infectious diseases 2008-07, Vol.12 (4), p.410-415
• Main Authors: Veras, Jamaira Fereira, do Carmo, Luiz Simeão, Tong, Lawrence C, Shupp, Jeffrey W, Cummings, Christiano, dos Santos, Deise Aparecida, Cerqueira, Mônica Maria Oliveira Pinho, Cantini, Alvaro, Nicoli, Jacques Robert, Jett, Marti
• Format: Article
• Language: English
• Subjects: Bacterial diseases; Biological and medical sciences; Brazil - epidemiology; Coagulase - metabolism; Coagulase-negative; Disease Outbreaks; Enterotoxins - genetics; Enterotoxins - metabolism; Food poisoning; Gene Expression Profiling; Human bacterial diseases; Humans; Infectious Disease; Infectious diseases; Medical sciences; PCR; Pulmonary/Respiratory; Staphylococcal enterotoxin; Staphylococcal Food Poisoning - epidemiology; Staphylococcal Food Poisoning - microbiology; Staphylococcal infections, streptococcal infections, pneumococcal infections; Staphylococcus - classification; Staphylococcus - genetics; Staphylococcus - pathogenicity
• ISSN: 1201-9712; 1878-3511
• DOI: 10.1016/j.ijid.2007.09.018

Summary Objectives The purpose of this study was to identify enterotoxin genes from isolates of coagulase-negative staphylococci and coagulase-positive staphylococci obtained from dairy products, responsible for 16 outbreaks of food poisoning. Methods From the pool of 152 staphylococcal isolates, 15 coagulase-negative and 15 coagulase-positive representatives were selected for this study. The 15 coagulase-negative isolates were tested for the presence of coa and femA genes, which are known to be characteristic of Staphylococcus aureus . After testing for enterotoxin genes by polymerase chain reaction (PCR), the 30 selected isolates were tested for the presence of toxin by immunoassay. Results Seven of the coagulase-negative isolates amplified the coa gene and were subsequently reclassified as coagulase-positive. Twenty-one of 30 selected isolates had staphylococcal enterotoxin genes and most of these produced toxin as well. The most frequently encountered enterotoxin genes were sea and seb . Among eight coagulase-negative isolates, five had enterotoxin genes, all of which were found to have detectable toxin by immunoassay. Conclusions The results from this study demonstrate that coagulase-negative as well as coagulase-positive staphylococci isolated from dairy products are capable of genotypic and phenotypic enterotoxigenicity. Furthermore, these data demonstrate that PCR is a sensitive and specific method for screening outbreak isolates regardless of coagulase expression.