BACTERIAL PATHOGENICITY AND CHARACTERISATIONEn t ero pat h og en i ci ty m a r kers i n Escrt erichia coli isolated from infants with acute diarrhoea and healthy controls in Rio de Janeiro, Brazil Sa'o Paulo, Brazil Faeces from urban children < 2 years old with acute diarrhoeal illness and from nondiarrhoeal infants (controls) were examined for Escherichia coli and other enteropathogens. A total of 990 E. coli isolates from 100 patients and 50 controls was tested for enteropathogenic E. coli (EPEC) serotype (O:H), adherence to HEp-2 cells after incubation for 3 and 6 h, fluorescent actin staining (FAS), DNA hybridisation with EAF, eaeA, STh, STp and EAggEC probes and production of heat-labile enterotoxin (LT) and verocytotoxin (VT) with Y1 and Vero cells. EPEC were the most prevalent enteropathogens in patients (32.7%; and 14% in controls). Enteroinvasive E. coli (EIEC) and Vero cytotoxin-producing E. coli (VTEC) were not detected. The rate of isolation of enterotoxigenic E. coli (ETEC) was identical in both groups. Among the EPEC isolates the prevalent serotypes were Olll:H2, 055:NM and 01 19:H6. Localised adherence (LA) was found significantly more frequently in isolates from patients (19.6%) than controls (2.1%). All LA-positive EPEC isolates were FASf and eaeAf, but only 75.2% of them hybridised with the EAF probe. Diffusely adhering E. coli (DAEC) and enteroaggregative E. coli (EAggEC) were found with equal frequency in patients and controls. Twenty-seven E. coli isolates were negative for EAF but positive for eaeA and FAS and produced LA in 6-h adherence tests. These EAF-/eaeA+ strains were the only putative enteropathogen identified in seven patients and were not found in controls. The ability of these strains to elicit ultrastructural cell alterations and cell-signalling events was evaluated in Caco-2 cells (human colon carcinoma cell line) by the gentamicin invasion assay and by transmission electron microscopy. The numbers of intracellular bacteria in cell invasion tests varied from 0.4% to 1.6% of the cellassociated bacteria after a 6-h incubation period. Tyrosine phosphorylation of host cell proteins was assessed in HEp-2 cells by immunofluorescence microscopy and all strains gave positive results. EAF-/eaeA+ E. coli strains express most of the virulence properties found among true EPEC strains and can be a relevant cause of infant diarrhoea in developing countries.

The present study evaluated the incidence of Listeria spp. in some Brazilian cheeses obtained from retail stores in Rio de Janeiro. Of 103 samples of various types of cheese examined as recommended in the Listeria isolation protocol of the Health Protection Branch of Canada, 11 (10.68%) were contaminated by Listeria monocytogenes, 13 (12.62%) by Listeria innocua, 6 (5.83%) by Listeria grayi, and 1 (0.97%) by Listeria welshimeri. A higher incidence of L. monocytogenes was observed mainly in the homemade Minas Frescal cheeses (a Brazilian soft white cheese, eaten fresh), 7 of 17 (41.17%), followed by ripened cheeses, 3 of 53 (5.67%), and industrially manufactured Frescal (Minas and Ricotta) cheeses, 1 of 33 (3.03%). Three serotypes (l/2a, l/2b and 4b) were observed among the strains of L. monocytogenes isolated, all of them being frequently involved in outbreaks of foodborne listeriosis and sporadic cases of the disease all over the world.

Aims: The purpose of this study was to determine the susceptibility of Campylobacter jejuni and Campylobacter coli isolates to antimicrobial agents and to investigate the presence of plasmid DNA. Methods and Results: A total of 15 clinical isolates from children faeces, and 29 animal isolates of Campylobacter jejuni (n 22) and Campylobacter coli (n 22) were tested for susceptibility to 9 antimicrobial agents using a disc diffusion method, and screened for the presence of plasmid DNA by agarose gel electrophoresis. Of the 44 isolates, 56á8% were resistant to sulphonamide, 25% to nor¯oxacin, 18á2% to erythromicin, cipro¯oxacin and ampicillin, and 13á6% to tetracycline. All isolates were susceptible to gentamicin, chloramphenicol and cefotaxime. Plasmids were detected in one Camp. jejuni (4á54%) strain isolated from sheep and in six (27á27%) Camp. coli strains isolated from rhesus monkey(3), swine(2), and poultry(1) with sizes ranging from 3á4 to 50 kb. Conclusions: The majority of the human isolates were susceptible to antibiotics commonly used for the treatment of campylobacteriosis. Signi®cance and Impact of the Study: The origin and spread of Campylobacter resistance to antibiotics are discussed, with particular respect to the current situation in Brazil.

Raw beef samples (n = 105) were examined for diarrheagenic Escherichia coli (DEC) using standard methods. The isolates obtained (n = 1,066) were screened for Shiga-like toxins (SLT-I and SLT-II), cytolethal distending toxin (CLDT), enterotoxins (LT-I and STa), and classical enteropathogenic (EPEC) and enteroinvasive (EIEC) serogroups. Seventy-three (6.8%) DEC isolates representing 42 strains isolated from 34 (32.4%) beef samples were detected. SLT-producing E. coli (SLTEC) was the most frequent DEC category found and corresponded to 21 (50%) of the 42 DEC strains. Several serotypes were detected among the SLTEC and some of them have been found previously in animal and human isolates, but E. coli O157:H7 was not isolated. Other virulence markers found in DEC strains included enterotoxin production (38.1%), CLDT (7.1%), and EPEC serogroups (4.3%). This is the first report of CLDT-producing E. coli (CLDTEC) isolated from food samples in Brazil. Production of both SLT-I and LT-I was found in one E. coli isolate, and 3 beef samples harbored both SLTEC and ETEC strains. Although a high frequency of DEC groups was found in commercial beef samples in Rio de Janeiro City, Brazil, the significance of these strains as agents of human diarrhea remains to be established.

Nosocomial infections are an important cause of morbidity and mortality all over the world. It has been shown that appropriate environmental hygienic and disinfection practices can be very helpful to hospital infection control. The purpose of this study was to evaluate the bactericidal activity of some disinfectants against antibiotic-susceptible and antibiotic-resistant hospital bacterial isolates. The susceptibility of 27 clinical isolates to disinfectants and antibiotics was determined by the Association of Official Analytical Chemist's (AOAC) Use-Dilution method and by the Kirby-Bauer method, respectively. All strains tested were susceptible to sodium hypochlorite, glutaraldehyde and to the association quaternary ammoniumformaldehyde -ethyl alcohol disinfectants. However, the susceptibility of strains to phenol and to one quaternary ammonium compound was variable. Among twenty-one antibiotic-multiresistant strains (methicillin-resistant staphylococci, Enterococcus spp, Pseudomonas aeruginosa, Klebsiella pneumoniae, Proteus mirabilis, Enterobacter cloacae, Serratia marcescens and Escherichia coli) eleven (52%) and eight (38%) strains were resistant to the quaternary ammonium and phenol compounds, respectively. Among six isolates that demonstrated susceptibility to antibiotics (staphylococci, Enterococcus spp, P. mirabilis, E. cloacae and E. coli) two strains (33%) showed resistance to these disinfectants. The results demonstrated the lack of correlation between antibiotic-susceptibility and susceptibility to disinfectants in hospital strains.

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The heat stability of staphylococcal enterotoxins A, B and C (SEA, SEB, SEC) in phosphate buffered saline solution at a concentration of 100 ng per ml indicated that normal cooking times and temperatures are unlikely to completely inactivate the toxins. The order of heat resistance of the three toxins was SEC&gt;SEB&gt;SEA.

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