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Molecular epidemiology of ceftazidime resistant Enterobacteriaceae from patients on a paediatric oncology ward
L C Hibbert-Rogers1, J Heritage, D M Gascoyne-Binzi
1Department of Microbiology, University of Leeds, UK.
Insights
Extended-spectrum beta-lactamase (ESBL) producing Enterobacteriaceae caused significant colonization in pediatric oncology patients. These multidrug-resistant bacteria persisted on the ward for years, highlighting the need for infection control.
Area of Science:
- Microbiology
- Infectious Diseases
- Genetics
Background:
- Extended-spectrum beta-lactamases (ESBLs) are enzymes that confer resistance to beta-lactam antibiotics.
- Enterobacteriaceae are a family of Gram-negative bacteria, some of which can produce ESBLs.
- Nosocomial infections in immunocompromised patients, such as those with cancer, are a significant concern.
Purpose of the Study:
- To investigate the prevalence and characteristics of Enterobacteriaceae producing extended-spectrum beta-lactamases (ESBLs) in a pediatric oncology ward.
- To identify the specific ESBLs present and their genetic basis.
- To assess the transmission dynamics and long-term persistence of these resistant bacteria.
Main Methods:
- Surveillance of pediatric oncology patients for ESBL-producing Enterobacteriaceae colonization and infection.
- Isolation and identification of bacterial strains from blood and fecal samples.
- Antimicrobial susceptibility testing.
- Plasmid DNA analysis and hybridization with TEM beta-lactamase gene probes.
- Nucleotide sequencing of beta-lactamase genes.
- Ribotyping and plasmid profiling for epidemiological analysis.
Main Results:
- 48% of pediatric oncology patients were colonized or infected with ESBL-producing Enterobacteriaceae.
- The majority of isolates were resistant to penicillins and ceftazidime, exhibiting multidrug resistance.
- Three types of ESBLs were identified: TEM-10B, TEM-12B, and TEM-26B, with TEM-12B and TEM-26B being most common.
- Evidence of cross-colonization between patients was confirmed through ribotype and plasmid profile analysis.
- ESBL-producing bacteria persisted on the ward for at least four years after the discontinuation of specific cephalosporins.
Conclusions:
- A high prevalence of ESBL-producing Enterobacteriaceae was observed in this pediatric oncology ward.
- The study identified specific ESBL types and provided evidence for patient-to-patient transmission.
- The long-term persistence of these resistant organisms underscores the challenges in controlling their spread in healthcare settings.
Abstract:
Between the autumn of 1989 and January 1990, 21 of the 44 children on the paediatric oncology ward of St. James's University Hospital, Leeds, UK were infected or colonised with Enterobacteriaceae producing extended-spectrum beta-lactamases. This represents 48% of the patients on the ward. Only six patients (14%) had microbiologically proven septicaemia caused by such bacteria during this period. Eighty-one isolates of Enterobacteriaceae producing extended-spectrum beta-lactamases derived from blood culture (7 isolates from 6 patients) or faecal samples (74 isolates) were available for examination. These comprised 28 Escherichia coli, 28 Klebsiella oxytoca, 11 Klebsiella pneumoniae, 10 Citrobacter freundii, 3 Enterobacter spp. and 1 Serratia marcescens. Clinical isolates were resistant to penicillins and to ceftazidime. Strains isolated in this study also showed multiple resistance to a range of antimicrobial agents. Transfer to a nalidixic acid resistant laboratory strain of E. coli UB5201 was attempted, but transfer of the ceftazidime resistance determinant was only successful in 25 isolates (31%). Examination of plasmid DNA revealed sequences in each isolate that hybridised with the TEM beta-lactamase gene probe used on a variety of plasmids ranging in size from 2.5- > 150 kb, sometimes found on several replicons in a single isolate. The TEM gene probe also hybridised with chromosomal DNA in a large number of isolates. Nucleotide sequence analysis demonstrated the presence of three extended-spectrum beta-lactamases: TEM-10B produced by two isolates, TEM-12B produced by 37 isolates and TEM-26B produced by 40 isolates. In two cases, isolates produced two beta-lactamases, and it proved impossible to identify these enzymes unequivocally. The genes encoding TEM-10B and TEM-26B both differ from TEM-12B by single nucleotide substitutions. Analysis of the ribotype patterns derived from the clinical isolates provided evidence for cross-colonisation between patients, and this was confirmed by analysis of the plasmid profiles. Four years after discontinuing ceftazidime and other extended-spectrum cephalosporins on this ward, patients were still colonised with bacteria that produced extended-spectrum beta-lactamases.