Merlin S. Bergdoll

Estimation of human dose of staphylococcal enterotoxin A from a large outbreak of staphylococcal food poisoning involving chocolate milk.

An outbreak of gastroenteritis in a school district in the United States was determined to be staphylococcal food poisoning due to 2% chocolate milk containing staphylococcal enterotoxin A (SEA). Twelve one-half pint (approx 0.28 l) cartons of the 2% chocolate milk from this outbreak were analyzed for the quantity of SEA present in the milk. The amount of SEA in the cartons varied from 94 to 184 ng with the average being 144 ng (mean = 139 +/- 45). The attack rate for vomiting among those who consumed more than one carton was greater (38.3%) than among those who consumed only one carton (31.5%) with the highest attack rate among those who consumed three or more cartons (44.4%).

An enterotoxin-like protein in Staphylococcus aureus strains from patients with toxic shock syndrome.

An enterotoxin-like protein, tentatively labeled enterotoxin F, was isolated from Staphylococcus aureus strains taken from patients with toxic shock syndrome. Antibodies specific for enterotoxin F were prepared in rabbits. Use of these antibodies showed that 130 (91.5%) of 142 S. aureus strains from patients with toxic shock syndrome produced enterotoxin F. Strains from toxic shock patients in eight other countries were identified as enterotoxin F producers. Only a small number of S. aureus strains from sources other than patients with toxic shock syndrome were found to produce enterotoxin F. Twenty-one of 111 controls had low antibody titers (less than 1:100) to enterotoxin F whereas 86 of 92 toxic shock patients had low acute phase antibody titers (less than 1:100) to enterotoxin F. Eight of 52 patients had serum conversion as shown by an increase in antibody titer to enterotoxin F in sera taken 21 to 60 days after onset of the illness. It may be possible to identify persons susceptible to toxic shock syndrome by measuring their antibody titer to enterotoxin F.

Enterotoxin H in staphylococcal food poisoning

Seven members of one family became ill with vomiting and diarrhea 4 h after eating a type of cheese produced in the state of Minas Gerais, Brazil. Staphylococcus aureus (2.9 × 108 CFU/g) that produced enterotoxin H (SEH) was isolated from the cheese. A low level of this enterotoxin was detected in the cheese extract before and after concentration 20-fold by copper chelate chromatography. The amount of SEH produced by the staphylococcal strain was 180 ng/ml of culture supernatant with production by the sac culture method. If only the ELISA ball kit had been used, it would have been concluded that enterotoxin D was the cause of the food poisoning.

Toxic Shock Syndrome: Management and Long-Term Sequelae

Little information is available on the optimal management of toxic shock syndrome and on its sequelae. The most appropriate antibiotic treatment, the efficacy of colloid infusions, and the potential role of gamma globulin preparations have not yet been completely ascertained. Coagulase-positive staphylococci associated with toxic shock syndrome had minimal inhibitory concentrations of 0.06 microgram/mL or less to rifampin, 0.25 microgram/mL or less to gentamicin, and 0.50 microgram/mL or less to both nafcillin and clindamycin. In the 36 patients studied abnormal chest roentgenograms were commoner in those who had received albumin than in those who had not. Radioimmunoassay showed antibody titers to staphylococcal enterotoxin F, a marker protein in toxic shock syndrome, of 1:4000 or more for intravenous gamma globulin (12/15 lots) and 1:40 000 or more for intramuscular gamma globulin. Major sequelae of toxic shock syndrome include late-onset rash, compromised renal function, cyanotic extremities, and prolonged neuromuscular abnormalities.

Characterization and Enterotoxigenicity of Staphylococci Isolated from Mastitic Ovine Milk in Spain

On the basis of glucose fermentation and lysostaphin sensitivity, 71 gram-positive, catalase-positive cocci, isolated from mastitic ovine milk in Spain, were classified as members of the genus Staphylococcus . Identification at the species level was accomplished by complete characterization of the staphylococcal strains. Fifty-nine of the isolates were classified as S. aureus , 1 as S. simulans , 5 as S. epidermidis , a as S. haemolyticus and 5 could not be classified as any accepted or newly proposed species. The number of strains lysed by phages of S. aureus of human and bovine origin was 8 and 40, respectively. The phage pattern most frequently found was 78 (34 strains). Fifty of the S. aureus strains belonged to biotype C. Forty-nine of the S. aureus strains and 2 of the unclassified ones produced enterotoxin: 46 produced enterotoxin C, 2 produced enterotoxin A, 1 produced enterotoxin D and 2 produced both enterotoxins A and C. Forty-one of the 46 enterotoxin C producers belonged to biotype C, and 31 of these were lysed by phage 78.

Analytical methods for Staphylococcus aureus.

The staphylococcal enterotoxins are relatively low molecular weight proteins, 27000 to 29000 Da (Bergdoll, 1979). They are produced by the staphylococci, primarily Staphylococcus aureus, although the newer species, Staphylococcus intermedius and Staphylococcus hyicus have been reported to be enterotoxigenic (Adesiyun et al., 1984; Fukuda et al., 1984). The guideline followed for many years in the Food Research Institute to determine whether staphylococci might produce enterotoxin was to determine whether the particular strain produced either coagulase or thermonuclease (TNase). Formerly, both S. intermedius and S. hyicus would have been classified as S. aureus. Therefore, if we follow the current species classification, we cannot confine our testing of staphylococcal strains to S. aureus alone. To my knowledge, no one is currently working on the identification of additional enterotoxins although we do know that unidentified ones do exist. This is very difficult to accomplish because a specific biological test such as the monkey feeding test is necessary to identify the enterotoxin (Surgalla et al., 1953). Apparently, only about five percent of staphylococcal food poisoning outbreaks are due to unidentified enterotoxins. The enterotoxins that have been identified so far are classified as enterotoxins A (SEA), B (SEB), C 1 (SEC1), C~ (SEC2), C 3 (SEC3), D (SED) and E (SEE). The enterotoxin Cs are very closely related and can be identified by their cross-reactions with antibodies prepared against any one of the SECs. The other enterotoxins are identified by antibodies specific for each of the enterotoxins, although cross-reactions between SEB and the SECs (Lee et al., 1980) and SEA and SEE (Lee et al., 1978) do exist. Monoclonal antibodies have been prepared that are useful in the sandwich ELISA for the detection of SEB, SECs, SEA and SEE by one set of two antibodies for each group. Efforts to prepare monoclonal antibodies that cross-react with SEA, SED and SEE were generally unsuccessful, although an

Enterotoxigenicity of Staphylococcus intermedius of canine origin

Seventy-three staphylococcal strains isolated from pyrodermatitis in dogs were classified as Staphylococcus intermedius (52 strains) or Staphylococcus aureus (21 strains) on the basis of acetoin formation, anaerobic mannitol fermentation, aerobic maltose fermentation, pigmentation, coagulation of human plasma, and reaction on crystal violet agar. Enterotoxin was produced by 13 of the 52 S. intermedius strains and 6 of the S. aureus strains. The highest percentage of enterotoxigenic strains produced enterotoxins C (6 strains), D (7 strains), and E (6 strains). Four strains produced the toxic shock syndrome toxin-1. There was little difference in the antibiotic susceptibility between the enterotoxigenic and non-enterotoxigenic strains.

Enterotoxin and toxic shock syndrome toxin-1 production by staphylococci isolated from goat's milk

Abstract Staphylococci were isolated from 81 of 238 milk samples from 120 goats from 6 different French herds that presented no evidence of clinical mastitis. Staphylococcus aureus strains were isolated from five milk samples, with S. caprae and S. epidermidis being the most prevalent of the 76 coagulase-negative staphylococcal species isolated. An additional 92 staphylococcal strains, including 48 S. aureus strains, that were isolated by several laboratories from goats milk, were also analyzed. 52 S. aureus strains were characterized; 48 (92.3%) were classified in the host-specific variety ovis, 1 (1.9%) was classified in the host-specific variety bovis and 3 (5.7%) were non-host-specific. All 48 strains classified as ovis, were crystal-violet type C; 37 (77.1%) reacted to phage 78, 43 (89.6%) reacted to phage 740, and 39 (81.2%) produced enterotoxin C but no other enterotoxins. Toxic shock syndrome toxin-1 (TSST-1) production was always associated with enterotoxin C production except for one strain that produced only TSST-1. One non-host-specific strain produced enterotoxin D. None of the 85 coagulase-negative strains tested produced enterotoxins or TSST-1.

Production of staphylococcal enterotoxin A in cream-filled cake

Cakes were baked with normal ingredients and filled with cream, inoculated with different size enterotoxigenic-staphylococcal inocula. Samples of the cakes were incubated at room temperature and put in the refrigerator. Samples of cake and filling were taken at different times and analyzed for staphylococcal count and presence of enterotoxin. The smaller the inoculum, the longer the time required for sufficient growth (10(6)) to occur for production of detectable enterotoxin. Enterotoxin added to the cake dough before baking (210 degrees C, 45 min) did not survive the baking. The presence of enterotoxin in the contaminated cream filling indicated this as the cause of staphylococcal food poisoning from cream-filled cakes. Refrigeration of the cakes prevented the growth of the staphylococci.

Importance of staphylococci that produce nanogram quantities of enterotoxin

Many staphylococcal strains produce enterotoxin, the toxin that is the cause of staphylococcal food poisoning. If a strain is enterotoxigenic it is possible for it to be involved in food poisoning. The gel diffusion methods were the first methods developed for detection of the enterotoxins and were thought adequate to detect their production. However, they were not adequate to detect enterotoxin in foods involved in food poisoning. When researchers began using the sensitive methods, such as enzyme-linked immunosorbent assay (ELISA) and reversed passive latex agglutination (RPLA), to check strains for enterotoxin production, some strains produced nanogram quantities of enterotoxin. When it was reported that several coagulase-negative species produced less than 10 ng/ml of enterotoxin, it was imperative to determine whether these strains produced enough enterotoxin in foods to cause food poisoning. At the present time research is under way to determine whether these strains produce enough enterotoxin in foods to cause food poisoning.