Proof of principle for successful characterization of methicillin-resistant coagulase-negative staphylococci isolated from skin by use of Raman spectroscopy and pulsed-field gel electrophoresis.
Coagulase-negative staphylococci (CNS) are among the most frequently isolated bacterial species in clinical microbiology, and most CNS-related infections are hospital acquired. Distinguishing between these frequently multiple-antibiotic-resistant isolates is important for both treatment and transmission control. In this study we used isolates of methicillin-resistant coagulase-negative staphylococci (MR-CNS) that were selected from a large surveillance study of the direct spread of MR-CNS. This strain collection was used to evaluate (i) Raman spectroscopy as a typing tool for MR-CNS isolates and (ii) diversity between colonies with identical and different morphologies. Reproducibility was high, with 215 of 216 (99.5%) of the replicate samples for 72 isolates ending up in the same cluster. The concordance with pulsed-field gel electrophoresis (PFGE)-based clusters was 94.4%. We also confirm that the skin of patients can be colonized with multiple MR-CNS types at the same time. Morphological differences between colonies from a single patient sample correlated with differences in Raman and PFGE types. Some morphologically indistinguishable colonies revealed different Raman and PFGE types. This indicates that multiple MR-CNS colonies should be examined to obtain a complete insight into the prevalence of different types and to be able to perform an accurate transmission analysis. Here we show that Raman spectroscopy is a reproducible typing system for MR-CNS isolates. It is a tool for screening variability within a collection of isolates. Because of the high throughput, it enables the analysis of multiple colonies per patient, which will enhance the quality of clinical and epidemiological studies.
Willemse-Erix
H F M
HF
Center for Optical Diagnostics and Therapy, Department of Medical Microbiology and Infectious Diseases, Erasmus MC, University Medical Center Rotterdam, Rotterdam, Netherlands.
Jachtenberg
J
J
Barutçi
H
H
Puppels
G J
GJ
van Belkum
A
A
Vos
M C
MC
Maquelin
K
K
D015373:Bacterial Typing Techniques / Q000379:methods*; D002353:Carrier State / Q000382:microbiology*; D016000:Cluster Analysis; D016172:DNA Fingerprinting / Q000379:methods; D016521:Electrophoresis, Gel, Pulsed-Field / Q000379:methods; D006801:Humans; D016106:Methicillin Resistance; D015203:Reproducibility of Results; D012867:Skin / Q000382:microbiology*; D013059:Spectrum Analysis, Raman / Q000379:methods*; D013203:Staphylococcal Infections / Q000382:microbiology*; D013210:Staphylococcus / Q000737:chemistry / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification