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Pyrolysis mass spectrometry of cephalosporin-resistant Enterobacter cloacae
1Department of Medical Microbiology, Queen Charlotte's and Chelsea Hospital, London, UK.
Abstract:
Thirteen clinical and four environmental isolates of third-generation cephalosporin-resistant Enterobacter cloacae (CREC) together with single isolates from the hands of a nurse and from a blood gas analyser were associated with two clusters of nosocomial infection. With an unrelated CREC isolate they had been typed by serotype, biotype, ribotype and phage-type and were examined by pyrolysis mass spectrometry (PYMS) as described here. PYMS data yielded two clusters, major and minor. All except one isolate in the major cluster corresponded to type group identity (serotype 07, biotype 62, ribotype D) which had caused neonatal sepsis and colonization. Multivariate analysis showed a homogeneous group consisting of this strain plus two outliers. The minor cluster included four different strains, one of which, serotype 03, biotype 62, ribotype C had caused excoriation of the buttocks and colonization.
Insights
Pyrolysis mass spectrometry identified two clusters of third-generation cephalosporin-resistant Enterobacter cloacae (CREC) linked to hospital infections. One major cluster, primarily serotype 07, ribotype D, caused neonatal sepsis, while a minor cluster involved other strains.
Area of Science:
- Microbiology
- Infectious Diseases
- Analytical Chemistry
Background:
- Nosocomial infections pose a significant threat in healthcare settings.
- Third-generation cephalosporin-resistant Enterobacter cloacae (CREC) are emerging pathogens.
- Effective typing methods are crucial for controlling CREC outbreaks.
Purpose of the Study:
- To investigate the molecular relatedness of CREC isolates associated with nosocomial infections.
- To differentiate between clinical and environmental CREC strains using advanced typing techniques.
- To identify the specific CREC strains responsible for neonatal sepsis and other hospital-acquired conditions.
Main Methods:
- Serotyping, biotyping, ribotyping, and phage typing were performed on clinical and environmental CREC isolates.
- Pyrolysis mass spectrometry (PYMS) was employed for rapid and detailed strain characterization.
- Multivariate analysis was used to assess the homogeneity of identified CREC clusters.
Main Results:
- PYMS analysis revealed two distinct clusters: a major cluster and a minor cluster.
- The major cluster predominantly comprised isolates of serotype 07, biotype 62, and ribotype D, linked to neonatal sepsis.
- The minor cluster contained four diverse strains, including one (serotype 03, ribotype C) associated with skin excoriation and colonization.
Conclusions:
- PYMS is an effective tool for rapidly clustering and differentiating CREC strains involved in nosocomial outbreaks.
- Specific CREC strains, particularly serotype 07/ribotype D, pose a significant risk for neonatal infections.
- Understanding strain diversity is essential for implementing targeted infection control strategies against CREC.