A study of the enterotoxigenicity of coagulase-negative and coagulase-positive staphylococcal isolates from food poisoning outbreaks in Minas Gerais, Brazil.
OBJECTIVE
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.
Veras
Jamaira Fereira
JF
Escola de Veterinária, Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, Minas Gerais, Brazil.
do Carmo
Luiz Simeão
LS
Tong
Lawrence C
LC
Shupp
Jeffrey W
JW
Cummings
Christiano
C
Dos Santos
Deise Aparecida
DA
Cerqueira
Mônica Maria Oliveira Pinho
MM
Cantini
Alvaro
A
Nicoli
Jacques Robert
JR
Jett
Marti
M
D001938:Brazil / Q000453:epidemiology; D003030:Coagulase / Q000378:metabolism; D004196:Disease Outbreaks; D004768:Enterotoxins / Q000235:genetics* / Q000378:metabolism; D020869:Gene Expression Profiling; D006801:Humans; D013202:Staphylococcal Food Poisoning / Q000453:epidemiology / Q000382:microbiology*; D013210:Staphylococcus / Q000145:classification / Q000235:genetics / Q000472:pathogenicity*
D003030:Coagulase; D004768:Enterotoxins