No abstract

Approximately 10% (89 isolates) of Klebsiella pneumoniae isolated in 1985 from patients in intensive care units in Clermont-Ferrand exhibited a complex resistance phenotype towards antibiotics. They were resistant to amino-, carboxy- and ureidopenicillins, aminoglycosides (except gentamicin), chloramphenicol, sulphonamides, tetracyclines and, most importantly, to cephalosporins (except cefoxitin and latamoxef) and to aztreonam. The metabolic profile of fifty isolates was identical and seven were selected for further study. All the resistance characters in these isolates were transferable to Escherichia coli by conjugation and were lost en bloc after treatment with ethidium bromide. Agarose gel electrophoresis of crude lysates of the wild types and their transconjugants indicated that the multiple resistances were mediated by a 95kb plasmid, pCF04. The seven isolates selected for study and their corresponding transconjugants, constitutively produced a plasmid-mediated beta-lactamase with a pI of 6.3 that was much more active against third-generation cephalosporins than against cephalothin. The substrate profile and the isoelectric-focusing behaviour of this enzyme differed from those of other known plasmid-mediated beta-lactamases, and the enzyme was designated CTX-1. A chromosomally-encoded SHV-1 (PIT-2) penicillinase (pI 7.7) was also present in the seven K. pneumoniae isolates but did not transfer. Resistance to aminoglycosides in the K. pneumoniae isolates was due to synthesis of a 6'-aminoglycoside acetyltransferase type IV. Our data indicate an epidemic of antibiotic multiply-resistant strains of K. pneumoniae producing a new beta-lactamase.

Introduction Preventing carriage of potentially pathogenic micro-organisms from the aerodigestive tract is an infection control strategy used to reduce the occurrence of ventilatorassociated pneumonia in intensive care units. However, antibiotic use in selective decontamination protocols is controversial. The purpose of this study was to investigate the effect of oral administration of a probiotic, namely Lactobacillus, on gastric and respiratory tract colonization/infection with Pseudomonas aeruginosa strains. Our hypothesis was that an indigenous flora should exhibit a protective effect against secondary colonization.

During a 1-year survey of Shiga toxin-producing Escherichia coli (STEC) prevalence in central France, 2,143 samples were investigated by PCR for Shiga toxin-encoding genes. A total of 330 (70%) of 471 fecal samples collected from healthy cattle at the Clermont-Ferrand slaughterhouse, 47 (11%) of 411 beef samples, 60 (10%) of 603 cheese samples, and 19 (3%) of 658 stool specimens from hospitalized children with and without diarrhea were positive for thestx gene(s). A STEC strain was isolated from 34% (162 of 471) of bovine feces, 4% (16 of 411) of beef samples, 1% (5 of 603) of cheese samples, and 1.5% (10 of 658) of stool specimens. Of the 220 STEC strains isolated, 34 (15%) harbored thestx 1 gene, 116 (53%) harbored thestx 2 gene, and 70 (32%) carried both thestx 1 and stx 2 genes. However, 32 (14.5%) were not cytotoxic for Vero cells. Theeae gene, found in 12 (5%) of the 220 strains, was significantly associated with the stx 1 gene and with isolates from children. Sequences homologous to ehxAwere found in 102 (46%) of the 220 strains. Thirteen serotypes, OX3:H2, O113:H21, O113:H4, OX3:H21, O6:H10, OX178:H19, O171:H2, O46:H38, O172:H21, O22:H16, O91:H10, O91:H21, and O22:H8, accounted for 102 (55%) of 186 typeable isolates, and only one strain (0.5% of the 186 STEC isolates from cattle), belonged to the O157:H7 serotype. We showed that the majority of the STEC isolates from cattle, beef, and cheese were not likely to be pathogenic for humans and that the STEC strains isolated from children in this study were probably not responsible for diarrheal disease. Finally, the strains associated with hemolytic-uremic syndrome in the same geographical area were shown to belong to particular subsets of the STEC population found in the bovine reservoir.

Three clinical strains (Escherichia coli Rio-6, E. coli Rio-7, and Enterobacter cloacae Rio-9) collected in 1996 and 1999 from hospitals in Rio de Janeiro (Brazil) were resistant to broad-spectrum cephalosporins and gave a positive double-disk synergy test. Two bla CTX-M genes encoding ␤-lactamases of pl 7.9 and 8.2 were implicated in this resistance: the bla CTX-M-9 gene observed in E. coli Rio-7 and E. cloacae Rio-9 and a novel CTX-Mencoding gene, designated bla CTX