Saucy Enterics
July 1, 2002 3 minutes read
Abstract & Commentary
"What is food to one man is bitter poison to others."—Lucretius (99 BC-55 BC)
"Part of the secret of success in life is to eat what you like and let the food fight it out inside."—Mark Twain (1835-1910)
Synopsis: Both enterotoxigenic and enteroaggregative E Coli were recovered from table-top Mexican sauces in Guadalajara restaurants.
Source: Adachi JA, et al. Enteric pathogens in Mexican sauces of popular restaurants in Guadalajara, Mexico, and Houston, Texas. Ann Intern Med. 2002;136:884-887.
Adachi and colleagues in Houston collected samples of table-top Mexican sauces, including green and red salsas, guacamole, and pico de gallo from restaurants in the summer of 1998 to determine the frequency of their contamination by enteric pathogens. Seventy-one sauces were collected from 26 Guadalajara area restaurants popular with US travelers, as well as 25 sauces from 12 Mexican-style restaurants in Houston.
Escherichia coli was recovered in culture from 47 of 71 (66%) Guadalajara sauces at a median density of 1000 colony-forming units (CFUs) (range, 0-80,000 CFU) per gram. Ten of 25 (40%) of Houston samples yielded E coli with a median of 0.0 CFU/g. Both the frequency and the degree of contamination were significantly greater in the Guadalajara than in the Houston samples. The most consistently contaminated sauce in both cities was guacamole but, among the Guadalajara samples, the highest levels of contamination (median, 1000 CFU/g) were in pico de gallo. The mean pH of the sauces in the 2 cities did not significantly differ. Enterotoxigenic E coli (ETEC) were detected in 9% and enteroaggregative E coli (EAEC) in 44% of the sauces from Guadalajara that were tested for the presence of these organisms. Neither organism was detected in any of the Houston samples. No enteropathogens other than these 2 types of E coli were detected.
Comment by Stan Deresinski, MD, FACP
Why is it that the things that make food taste good seem too often be bad for you? This study found that the piquant sauces provided at restaurants in cities in Texas and Mexico are commonly contaminated with enteric bacteria, but that the level of contamination was higher in the Mexican samples studied and enteric pathogens were isolated only from the latter. Adachi et al point out that, while the Houston sauces were refrigerated before being served, those in Guadalajara were prepared on-site and were not refrigerated and, in addition, may have been handled by more individuals than those in Texas.
A study of herbs and spices being sold in markets in Mexico found high levels of aerobic bacteria in most samples of garlic powder, cumin seed, and black pepper, with lower levels in oregano and bay leaves (Garcia). In addition, Aspergillus niger was found in 29% of samples, Rhizopus spp. in 19%, and Penicillium spp. and Cunninghamella in 8%. In fact, purchased spices in any country are not sterile. Thus, the European Spice Association specifications of quality minima for herbs and spices include the following:
- Salmonella absent in (at least) 25 g;
- Yeast & moulds 105/g target, 106/g absolute maximum;
- E Coli. 102/g target, 103/g absolute maximum.
Thus, while regulations are aimed at preventing importation of spices contaminated with enteric pathogens, relatively high concentrations of other microbes are considered acceptable.
In this study of prepared sauces, enteric pathogens were recovered from sauces at Guadalajara restaurants. Adachi et al point out that this is one of the first demonstrations of EAEC in food. Adachi et al have demonstrated that EAEC is a major cause of traveler’s diarrhea in several regions and, in fact, is as common a cause of traveler’s diarrhea in Guadalajara as ETEC.1,2
Dr. Deresinksi, Clinical Professor of Medicine, Stanford; Associate Chief of Infectious Diseases, Santa Clara Valley Medical Center, is Editor of Infectious Disease Alert.
References
1. Adachi JA, et al. Clin Infect Dis. 2001;32:1706-1709.
2. Adachi JA, et al. J infect Dis. 2002;185:1681-1683.
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