Extended-spectrum beta-lactamase-producing Enterobacteriaceae in community and private health care centers

Abstract

In 1999, 39 of 2,599 isolates of the family Enterobacteriaceae (1.5%) collected by eight private laboratories in the Aquitaine region in France produced an extended-spectrum beta-lactamase (ESBL). Among these were 19 Enterobacter aerogenes isolates; 8 Klebsiella pneumoniae isolates; 6 Escherichia coli isolates; 3 Proteus mirabilis isolates; and 1 isolate each of Serratia marcescens, Morganella morganii, and Providencia stuartii. ESBL producers were isolated from 38 patients, including 33 residents of 11 clinics or nursing homes and 5 ambulatory patients. Seven different ESBLs were characterized. These mainly consisted of TEM-24 (25 isolates) and TEM-21 (9 isolates), but TEM-15 (2 isolates) and TEM-3, TEM-19, SHV-4, and CTX-M-1 (1 isolate each) were also characterized. Seven strains showed the coexistence of different TEM- and/or SHV-encoding genes, including a new SHV-1 variant, SHV-44, defined by the substitution R205L previously reported for SHV-3 in association with S238G. The epidemiology of the ESBL producers was investigated by random amplification of polymorphic DNA, typing by enterobacterial repetitive intergenic consensus PCR, analysis of resistance cotransferred with the ESBL, and analysis of the restriction profiles of the ESBL-encoding plasmids. Of the TEM-24-expressing strains, 18 were E. aerogenes isolates, including 9 from the same clinic, that were representatives of the epidemic clone disseminating in France. Of the TEM-21-producing strains that belonged to different species of the family Enterobacteriaceae (E. coli, K. pneumoniae, and P. mirabilis), 8 were isolated in the same nursing home. Outbreaks due to strain and/or plasmid dissemination in these clinic and nursing home were demonstrated. The presence of ESBL producers in five ambulatory patients probably resulted from nosocomial acquisition. Our data highlight the serious need to monitor patients for ESBL-producing Enterobacteriaceae in general practice.

FIG. 1.

RAPD and ERIC-PCR fingerprints of E. aerogenes strains. The profiles obtained with primers AP12h, ERIC2, and ERIC1R are shown. Lanes 1 and 2, unrelated strains of E. aerogenes used as controls; lanes 3 and 4, the TEM-24b-producing E. aerogenes strain belonging to the clone responsible for the present epidemic in France; lanes 5 to 9, representative TEM-24-producing strains (profile Ea-1); lane 10, TEM-3-producing strain (profile Ea-2); lanes M, molecular weight marker (lambda phage DNA digested with PstI).

FIG. 2.

Plasmid profile analysis of TEM-24b-producing (A) and TEM-21-producing (B) members of the family Enterobacteriaceae. EcoRI restriction plasmid patterns were obtained from transconjugants or transformants. Lane 1, E. coli strain of molecular type Ec1 (profile A-1); lane 2, K. pneumoniae strain of molecular type Kp1 (profile A-2); lanes 3 and 4, K. pneumoniae strain of molecular type Kp2 (profiles A-3); lane 5, S. marcescens (profile A-4); lane 6, M. morganii (profile A-2); lane 7, P. stuartii (profile A-1); lanes 8 to 13, TEM-24-producing E. aerogenes strain of molecular type Ea1 divided into profile A-1 (lanes 8 to 10), profile A-2 (lane 11), profile A-4 (lane 12), and profile A-5 (lane 13); lanes 14 to 22, TEM-21-producing strains with the B profile. Lanes M, molecular weight marker (lambda phage DNA digested with PstI).