Differentiation of typical and atypical enteropathogenic Escherichia coli using colony immunoblot for detection of bundle-forming pilus expression.

AIMS: The aim of study was to develop a colony immunoblot assay to differentiate typical from atypical enteropathogenic Escherichia coli (EPEC) by detection of bundle-forming pilus (BFP) expression. METHODS AND RESULTS: Anti-BFP antiserum was raised in rabbits and its reactivity was confirmed by immunoelectron microscopy and by immunoblotting recognizing bundlin, the major pilus repeating subunit. The bacterial isolates tested in the colony immunoblot assay were grown in different media. Proteins from bacterial isolates were transferred to nitrocellulose membrane after treatment with phosphate buffer containing Triton X-100, EDTA and sodium chloride salts. When 24 typical EPEC and 96 isolates including, 72 atypical EPEC, 13 Gram-negative type IV-expressing strains and 11 enterobacteriaceae were cultivated in Dulbecco's Modified Eagle's Medium agar containing fetal bovine serum or in blood agar in the presence of CaCl(2) , they showed a positivity of 92 and 83%, and specificity of 96 and 97%, respectively. CONCLUSION: The assay enables reliable identification of BFP-expressing isolates and contributes to the differentiation of typical and atypical EPEC. SIGNIFICANCE AND IMPACT OF THE STUDY: The colony immunoblot for BFP detection developed in this study combines the simplicity of an immunoserological assay with the high efficiency of testing a large number of EPEC colonies.

Shiga toxin-producing Escherichia coli (STEC): Zoonotic risks associated with psittacine pet birds in home environments.

Psittacidae are frequently bred as pets worldwide, but little is known about the zoonotic risks of these animals. The objective of this study was to investigate the presence of Shiga toxin-producing Escherichia coli (STEC) in the feces of psittacine birds housed as pets. A total of 171 fecal samples (67 cockatiels, 59 budgerigars, and 45 agapornis) were cultured. Forty-two (E. coli) strains were identified, and the presence of the eae, stx1, and stx2 genes was determined using PCR. The antimicrobial resistance profiles of the STEC strains were determined using the disk diffusion method and phylogenetic analysis according to the new Clermont phylotyping method. Using these methods, 19.4% (8/42) of the STEC strains were determined to be positive for the eae and stx2 genes. The results revealed a STEC frequency of 4.6% in the birds (8/171), with a percentage of 8.47% in budgerigars (5/59), 4.47% in cockatiels (3/67), and 0% in agapornis (0/45). None of the STEC isolates belonged to the O157 serogroup. Most of the strains were classified as sensitive to the 18 antibiotics tested. None of the strains exhibited a multiresistance profile. In the phylogenetic analysis, two strains were classified as non-typeable, three were classified as B2, two were classified as F, and one was classified as Clade I. Seven of the eight STEC strains showed a clonal profile using AFLP. E. coli strains that are stx2(+) plus eae(+) are usually associated with severe human diseases such as hemorrhagic colitis and hemolytic-uremic syndrome. The STEC-positive results indicate the zoonotic risk of breeding psittacidae in home environments.

[Mite contamination in polished rice and beans sold at markets]. / Contaminacao por acaros em arroz polido e feijao comercializados a granel.

OBJECTIVE: To evaluate mite contamination rate in grains commercialized in nine municipal markets of the city of São Paulo, in the period from November 1989 to November 1990. METHODS: 23 samples of polished rice and 53 samples of beans were microscopically examined after sieving, once a week and during 42 days at air temperature. Other sample fractions were kept in an incubator at 25 degrees C and 75% Relative Humidity (RH) during 28 days. RESULTS: Samples were negative for mites in the first day of analysis and were detected after incubation. Samples incubated revealed a higher percentage of positive examinations for mites (incidence): 31.7% (and 1,845 mites); while samples kept at air temperature showed only 6.9% (and 45 mites). Samples of polished rice were more contaminated in comparison to the ones of beans. There was a larger amount of mites when the mean monthly temperature of the laboratory was between 21.5 degrees C to 22.5 degrees C (37. 8%) and humidity between 73.5% to 74.5% (31.1%). CONCLUSIONS: The predominant species was Tyrophagus putrescentiae and other identified species were Blomia tropicalis, Cheyletus spp., Blattisocius tarsalis, and others. Mite population had a higher proliferation rate during spring, summer and in the beginning of autumn, due to highest temperature and humidity. These results confirm the importance of improving grains storage, to avoid mites proliferation.