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Inter-strain comparison by pyrolysis mass spectrometry of Staphylococcus aureus isolates associated with nosocomial
P R Sisson1, E Nagy, Z Kòczián
1Public Health Laboratory, General Hospital, Newcastle upon Tyne, UK.
Abstract:
Pyrolysis mass spectrometry was used to characterise Staphylococcus aureus isolates from an outbreak of postoperative wound infections on a mixed surgical ward. The PyMS results were compared with those of phage typing. Both suggested a single strain of S. aureus, of phage type 3C, 55, 71, was responsible for six of the 13 wound infections. PyMS differentiated an isolate from a member of staff of similar phage type to the epidemic strain, which had previously been considered to be the point source for the outbreak. PyMS is a rapid and inexpensive technique for investigating nosocomial outbreaks, including those caused by S. aureus and, in this instance, was more discriminatory than phage typing.
Insights
Pyrolysis mass spectrometry (PyMS) rapidly identified the Staphylococcus aureus strain causing a hospital outbreak. This technique proved more effective than traditional phage typing in distinguishing bacterial isolates during the investigation.
Area of Science:
- Microbiology
- Infectious Diseases
- Analytical Chemistry
Background:
- Nosocomial outbreaks, particularly those involving Staphylococcus aureus, pose significant challenges in healthcare settings.
- Accurate and rapid strain characterization is crucial for effective outbreak investigation and control.
- Traditional methods like phage typing may have limitations in differentiating closely related strains.
Purpose of the Study:
- To evaluate the utility of Pyrolysis mass spectrometry (PyMS) for characterizing Staphylococcus aureus isolates from a postoperative wound infection outbreak.
- To compare the discriminatory power of PyMS with conventional phage typing in an epidemiological investigation.
- To assess PyMS as a rapid and cost-effective tool for managing nosocomial infections.
Main Methods:
- Pyrolysis mass spectrometry (PyMS) was employed to analyze Staphylococcus aureus isolates.
- Phage typing was performed concurrently for comparative analysis.
- Isolates were obtained from patients with postoperative wound infections and healthcare staff.
Main Results:
- Both PyMS and phage typing indicated a single Staphylococcus aureus strain (phage type 3C, 55, 71) was responsible for six of 13 infections.
- PyMS successfully differentiated an isolate from a staff member, which had a similar phage type to the epidemic strain.
- PyMS demonstrated greater discriminatory power compared to phage typing in this outbreak scenario.
Conclusions:
- Pyrolysis mass spectrometry is a rapid, inexpensive, and highly discriminatory technique for investigating nosocomial outbreaks caused by Staphylococcus aureus.
- PyMS offers advantages over traditional phage typing for strain differentiation, aiding in accurate outbreak source identification.
- The findings support the integration of PyMS into routine surveillance and outbreak management protocols for healthcare-associated infections.