Monitoring and Molecular Characterization of Staphylococcus Aureus Isolated from Chronic Wounds

Objective: Researchers analyzed chronic wounds treated with 2% hydrogel to determine whether the presence of methicillin-resistant Staphylococcus aureus (MRSA) is related to the presence of clinical signs of infection.

Methods: Thirty-five patients were recruited for this descriptive study using a quantitative approach. Staphylococcus aureus was identified by matrix-assisted laser desorption ionization time-of-flight mass spectrometry. Antibiotic susceptibility was determined using a disk diffusion test according to Clinical and Laboratory Standards Institute standards. Polymerase chain reaction, pulsed-field gel electrophoresis, and multilocus sequence typing were performed. Statistical analyses were performed using Spearman correlation coefficients for the variables MRSA and clinical signs of infection.

Main Outcome Measures: The identification of MRSA or methicillin-sensitive S aureus (MSSA), presence or absence of an infection in the wound, and molecular characterization of bacteria were measured.

Main Results: Of the 35 patients analyzed, 8 (22.9%) were classified as having an infection in their wounds. Spearman ρ indicated a strong positive correlation between the increase in the number of clinical signs of infection and MSSA (P =.84), but only a moderate positive correlation with MRSA (P =.60). The S aureus clonal pattern was unique for each of the major bacteria isolated. Global MRSA sequence-type clones (ST-1 and ST-72) were detected in 2 patients.

Conclusions: Compared with those colonized by MSSA, chronic wounds colonized by MRSA did not display a strong correlation with the presence of a greater number of clinical signs of infection.