Outbreak of multi-resistant Klebsiella oxytoca involving strains with extended-spectrum β-lactamases and strains with extended-spectrum activity of the chromosomal β-lactamase

• Published in: Journal of antimicrobial chemotherapy 2004-11, Vol.54 (5), p.881-888
• Main Authors: Decré, Dominique, Burghoffer, Béatrice, Gautier, Valérie, Petit, Jean-Claude, Arlet, Guillaume
• Format: Article
• Language: English
• Subjects: Antibiotics. Antiinfectious agents. Antiparasitic agents; beta-Lactamases - metabolism; Biological and medical sciences; Chromosomes, Bacterial; Conjugation, Genetic; Disease Outbreaks; Drug Resistance, Multiple, Bacterial; Drug Synergism; Electrophoresis, Gel, Pulsed-Field; Klebsiella oxytoca; Klebsiella oxytoca - drug effects; Klebsiella oxytoca - enzymology; Klebsiella oxytoca - genetics; Medical sciences; Microbial Sensitivity Tests; OXY-2 β-lactamase; Pharmacology. Drug treatments; Polymerase Chain Reaction; TEM-129; TEM-7
• ISSN: 0305-7453; 1460-2091
• DOI: 10.1093/jac/dkh440

Objectives: This study was conducted to analyse broad-spectrum cephalosporin-resistant Klebsiella oxytoca strains. Methods: The 57 isolates studied were recovered from clinical specimens (n=23) or from rectal swabs (n=34) during a 26-month period. Antibiotic susceptibility patterns were determined using standard agar diffusion and dilution methods including the synergy test between extended-spectrum cephalosporins and clavulanic acid. ERIC-2 PCR and pulsed-field gel electrophoresis (PFGE) methods were used to study the clonal relatedness of the strains. Plasmid-mediated and chromosomal β-lactamases were characterized by mating and specific bla gene amplification and sequencing. Results: Four different antibiotic resistance patterns were identified whereas ERIC-2 PCR and PFGE revealed six main profiles. Extended-spectrum β-lactamases (ESBLs) were found in 32 strains: TEM-7 (n=26), TEM-129 (n=1), TEM-3 (n=4), SHV-2 (n=1). The new TEM-type β-lactamase, TEM-129, differed from TEM-7 by one mutation (Glu-104→Lys). All TEM-7 or TEM-129 producers were genetically related. Twenty-five other strains with identical ERIC-2 PCR and PFGE profiles harboured a blaOXY-2 gene different from the reference gene: 24 strains displayed one substitution (Ala-237→Ser) in the KTG motif and one strain, highly resistant to ceftazidime, showed an additional substitution (Pro-167→Ser). Conclusions: The study demonstrated that the majority of strains (n=52) harbouring the OXY-2-type β-lactamase corresponded to two clones. The first clone (n=27) corresponded to ESBL-producing strains. The second clone (n=25) displayed extended-spectrum activity of the chromosomal β-lactamase.