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Rapid inter-strain comparison by pyrolysis mass spectrometry of coagulase-negative staphylococci from persistent CAPD
R Freeman1, F K Gould, R Wilkinson
1Department of Microbiology, University of Newcastle upon Tyne, UK.
Abstract:
Pyrolysis mass spectrometry (PyMS) was used as a method of rapid inter-strain comparison of 19 isolates of coagulase-negative staphylococci from episodes of CAPD peritonitis. Thirteen isolates were from multiple, but distinct, episodes of peritonitis in 6 patients and the remaining 6 isolates were from 6 patients with single episodes. The results, expressed in terms of identity/non-identity of strains, were compared with those obtained using an established typing system comprising an extended antibiogram, determination of biotype and plasmid profile analysis. The PyMS results for inter-strain comparison were in agreement with the reference typing scheme results. PyMS can be used in this setting to rapidly obtain evidence that persistent infection is/is not likely to be due to the same organism, although it cannot be used for formal typing. The results by both methods showed that serial, apparently distinct, episodes of peritonitis over periods as long as 120 days may be due to the same strain of coagulase-negative staphylococcus. Clinically based distinctions between recurrence of infection (same strain) and re-infection (different strains) may not always be supported by the microbiological evidence.
Insights
Pyrolysis mass spectrometry (PyMS) rapidly distinguishes between same and different bacterial strains causing peritonitis. This method helps determine if persistent infections are due to the same coagulase-negative staphylococci strain over time.
Area of Science:
- Microbiology
- Infectious Diseases
- Analytical Chemistry
Background:
- Peritonitis in continuous ambulatory peritoneal dialysis (CAPD) patients often involves coagulase-negative staphylococci.
- Distinguishing between recurrent infection by the same strain and re-infection by a new strain is crucial for effective treatment.
- Established typing methods can be time-consuming for rapid clinical decision-making.
Purpose of the Study:
- To evaluate Pyrolysis Mass Spectrometry (PyMS) as a rapid method for inter-strain comparison of coagulase-negative staphylococci isolates from CAPD peritonitis.
- To compare the efficacy of PyMS with a conventional, established typing scheme.
Main Methods:
- Pyrolysis mass spectrometry (PyMS) was employed for rapid analysis of 19 coagulase-negative staphylococci isolates.
- Isolates were obtained from single and multiple episodes of CAPD peritonitis in patients.
- PyMS results were compared against a reference typing system including antibiogram, biotype, and plasmid profiling.
Main Results:
- PyMS demonstrated agreement with the established typing scheme for inter-strain comparison.
- The study confirmed that PyMS can rapidly provide evidence for or against persistent infection by the same organism.
- Both methods indicated that serial peritonitis episodes, even over 120 days, can be caused by the same bacterial strain.
Conclusions:
- Pyrolysis mass spectrometry is a valuable tool for rapid inter-strain comparison in the context of CAPD peritonitis.
- PyMS can quickly support clinical assessments of infection recurrence versus re-infection.
- Microbiological findings may challenge clinical distinctions between recurrent and new infections, highlighting the need for precise strain typing.