Using MALDI-TOF MS typing method to decipher outbreak: the case of Staphylococcus saprophyticus causing urinary tract...

Area of Science:

• Microbiology
• Epidemiology
• Infectious Diseases

Background:

• Staphylococcus saprophyticus is a primary cause of urinary tract infections (UTIs).
• A surveillance system detected an unusual rise in S. saprophyticus UTIs in Marseille hospitals in December 2014.
• This indicated a potential community-acquired S. saprophyticus UTI outbreak.

Purpose of the Study:

• To investigate the suspected community S. saprophyticus UTI outbreak in Marseille.
• To analyze the clonal expansion of S. saprophyticus strains.
• To evaluate the utility of MALDI-TOF MS in outbreak investigations.

Main Methods:

• Utilized the BALYSES (Bacterial real-time Laboratory-based Surveillance System) for detection.
• Monitored the S. saprophyticus/Escherichia coli UTI ratio trends from 2002 to 2015.
• Employed Matrix-Assisted Laser Desorption Ionisation-Time of Flight Mass Spectrometry (MALDI-TOF MS) for strain analysis and cluster comparison.

Main Results:

• The S. saprophyticus/E. coli UTI ratio in Marseille showed a significant increase, peaking in December 2014.
• MALDI-TOF MS spectral analysis revealed a geographically restricted clonal expansion of S. saprophyticus strains in Marseille compared to Nice.
• An annual estimated ratio trend of 5.10^-6 was observed (p < 10^-3).

Conclusions:

• A specific cluster of S. saprophyticus strains has undergone geographically restricted expansion in Marseille.
• MALDI-TOF MS is a cost-effective method for investigating bacterial outbreaks.
• Enhanced surveillance and rapid diagnostic tools are crucial for managing UTI outbreaks.