Frequency of inhibitor-resistant TEM beta-lactamases in Escherichia coli isolates from urinary tract infections in France.

Over a six-month period in 1993, 2972 non-duplicated isolates of Escherichia coli causing urinary tract infections were collected in a French teaching hospital (n = 785) and in three private laboratories (n = 2187). The resistance rate to amoxycillin-clavulanate combination (MIC > 16 mg/l) was 25.0% in the hospital isolates and 10.0% in the community isolates. Respectively, 27.5% and 45.0% of hospital and community isolates resistant to amoxycillin-clavulanate exhibited an unusual beta-lactam resistance pattern, suggesting inhibitor-resistant TEM (IRT) beta-lactamase production. These isolates were highly resistant to amoxycillin-clavulanate (MIC90 > 1024 mg/L), but were susceptible to cephalosporins (MIC < 32 mg/L). Enzyme extracts of these IRT-producing strains focused at pI 5.2 (n = 100) or 5.4 (n = 53). DNA-DNA hybridization confirmed that the beta-lactamases involved in this resistance mechanism were TEM-1 derived and contained variations in the altered positions described in IRT enzymes. This study shows a total frequency of 4.9% of IRT-producing isolates among E. coli isolated from urine specimens.

A new colonization factor antigen (CFA/III) produced by enteropathogenic Escherichia coli O128:B12.

Fourteen enteropathogenic Escherichia coli strains isolated in the Dakar area (Senegal) from cases of diarrhoea in children were tested for the presence of adhesive factors. None of these strains possessed colonization factor antigens CFA/I or CFA/II, but one strain (strain 1373) presented a haemagglutination (HA) type similar to that of the CFA/I reference strain and failed to be agglutinated with CFA/I antiserum. Strain 1373 adhered strongly in vitro to human enterocyte brush borders. HA was not inhibited by D-mannose (which inhibits HA of type 1 pili) or by N-acetylneuraminic acid (which inhibits HA of CFA/I and CFA/II). HA and the adhesion of strain 1373 were inhibited by anti-CFA/III serum but not by anti-CFA/I or anti-CFA/II sera. The colonization factor antigen (CFA) of strain 1373 is a new antigen (which we propose to call CFA/III) and is distinct from CFA/I, CFA/II and type 1 pili. CFA/III has a protein subunit of molecular weight of about 16,000.

["In vitro" study of attachment to human enterocytes in "Escherichia coli" strains isolated from infants with diarrheal disease (author's transl)]. / Etude de l'attachement aux entérocytes humains in vitro de Escherichia coli isolés de selles diarrhéiques chez l'enfant.

One hundred and four Escherichia coli strains isolated in the Hospital Centre of Clermont-Ferrand (France) from faeces of 26 infants with diarrheal diseases and of 29 infants with non-diarrheal diseases were tested for their ability to adhere to intestinal villi of the human small intestine. The haemagglutination (HA) type (with human, bovine, chicken and guinea-pig erythrocytes) and the agglutination of adhering strains by anti-colonization factor antigen I (CFA/I) serum and by anti-CFA/II serum were determined. Seventeen strains adhered to the brush border of the human small intestine. All these strains were isolated from infants with diarrhea; among these strains, only two possessed one CFA: one of them exhibited HA type I and was agglutinated by the anti-CFA/I serum; the second exhibited HA type II and was agglutinated by the anti-CFA/II serum. Six strains exhibiting HA type III and nine exhibiting other HA types were not agglutinated by anti-CFA/I or CFA/II sera. There were no relationship between the adherence and the serotypes or the antibiotic resistance of these strains.

[A study of chloramphenicol resistance in "Salmonella" and identification of the relevant R plasmid (author's transl)]. / Etude de la résistance au chloramphénicol de Salmonella et identification des plasmides R.

Seventy nine strains of salmonella of human origin were tested for antibiotic-resistance. Eighteen strains (11 Salmonella typhi-murium, 4 S. saint-paul and 3 S. dublin) were multiresistant, particularly to chloramphenicol. All the strains were able to transfer their resistance by conjugation. Thirteen conjugation R plasmids were classified into five incompatibility groups: I1, N, H1, M and B. Molecular studies showed that the DNA structures of the four IncI1R plasmids differed from one another and also partly from the plasmid DNA structures of other IncI1R plasmid DNA isolated from salmonellae. In conclusion, chloramphenicol resistance was conferred by various R factors, and the R factors of the I1 incompatibility group appeared to have different plasmid structures.