Clinical and molecular analysis of extended-spectrum {beta}-lactamase-producing enterobacteria in the community setting

Abstract

During a previous survey, five extended-spectrum beta-lactamase (ESBL)-producing enterobacteria (ESBLE) (two Enterobacter aerogenes isolates expressing TEM-24 b, two Escherichia coli isolates expressing TEM-21 or TEM-24 b, and one Klebsiella pneumoniae isolate expressing SHV-4/TEM-15) responsible for urinary tract infections (UTIs) were found among 1,584 strains collected from community patients. The aim of the present study was to elucidate the route of emergence of these typically nosocomial organisms in the community. Thus, the files of the five patients were analyzed over at least a decade, and potentially related ESBLE from hospitals or clinics were examined. Their enzymes were characterized at a molecular level, and the strains were typed by amplified-primed PCR, enterobacterial repetitive intergenic consensus PCR, and restriction plasmid profile. All patients (C1 to C5) had risk factors for ESBLE acquisition, including past history of hospitalization (2.5 to 23 months before). Four (C1 and C3 to C5) had previously received antibiotics (concomitantly to 35 months earlier), two (C1 and C3) had indwelling urinary catheters and recurrent UTIs, and three (C2, C3, and C5) formerly experienced ESBLE-induced UTIs (2 to 11 months before). The same ESBLE and/or an identical or similar ESBL-encoding plasmid was identified in the hospital ward (C1 to C4) or in a clinic (C5) where the patients had previously resided. Patients C1 and C4, infected with different ESBLE carrying a closely related plasmid, were hospitalized in the same unit. Persistence of ESBLE over at least a 5-year period was demonstrated for patient C3. Thus, community-acquired UTIs in these patients likely resulted from nosocomially acquired ESBLE or an ESBL-encoding plasmid followed by a prolonged digestive carriage.

FIG. 1.

AP-PCR and ERIC-PCR profiles of ESBLE. (A) AP-PCR profiles obtained with the primer ERIC-2 from TEM-24b-producing E. aerogenes strains Ea1-a (lane 1), Ea1-b (lane 2), Ea97 (lane 3), and Ea99 (Lane 4) and from an unrelated strain of E. aerogenes (lane 5). (B) AP-PCR profiles from E. coli Ec1 (lane 1) and Ec5 (lane 2) obtained with the primer AP12h. (C) AP-PCR profiles obtained with primer 208 (lanes 1 to 3) and primer 272 (lanes 4 to 6) from Kp7 (lanes 1 and 4, respectively) and Kp04 (lanes 2 and 5) and from an unrelated strain of K. pneumoniae (lanes 3 and 6). M, size ladder (DNA of λ phage digested by PstI). Sizes are indicated in kilobases.

FIG. 2.

EcoRI restriction profiles of TEM-24b (A)-and TEM-21 (B)-encoding plasmids. (A) Profile A-1 from the transconjugant of Ec1 (lane 1), profile A-2 from the transconjugant of Ea97 (lane 2), and profile A-4 from the transconjugant of Ea99 (lane 3). (B) Profile B from transconjugants of Ec5 and Kp95 (lanes 1 and 2, respectively). M, size ladder (DNA of λ phage digested by PstI).

FIG. 3.

Undigested plasmid profiles (A) and EcoRI restriction profiles (B) of SHV-4-encoding plasmids. (A) Undigested plasmid profiles from Kp7 (lane 1), Kp04 (lane 2), Kp92 (lane 3), and Kp93 (lane 4). (B) Profile C-1 from Kp7 and Kp04 (lanes 1 and 2, respectively) and profile C-2 from transconjugants of Kp92 and Kp93 (lanes 3 and 4, respectively). M, size ladder (DNA of λ phage digested by PstI).