Background: Recently, owing to antibiotic resistance, the incidence of methicillin-resistant Staphylococcus aureus  (MRSA) colonization among intensive care unit (ICU) patients has increased rapidly. So far, there are few studies on active screening of MRSA. The purpose of the current study was to verify the effectiveness of active screening and analyze the molecular epidemiological characteristics of MRSA in the region.
Methods: We collected 30 samples of the MRSA strains from a tertiary hospital in the Eastern Heilongjiang Province. Among them, 7 were retrieved through nasal vestibular swabs at the emergency ICU and 23 were obtained from clinical specimens. Additionally, relevant patient medical information was examined retrospectively and molecular epidemiology and risk factor analysis for MRSA were performed.
Results: Molecular epidemiology studies revealed that all strains of bacteria carried the mecA resistance gene. The Panton Valentine leukocidin (PVL), for instance, was detected at a rate of 13.33% (4/30). The Staphylococcus aureus  protein A (spa) types, found amongst our samples, were mainly t324, t437, t034, etc., and we discovered a new spa type t19702. We also revealed 3 types of SCCmec, namely, SCCmec type II, SCCmec type IVa, and SCCmec type V, with the most prevalent clonotypes being ST72 and ST59. In addition, we also found 7 new ST types, namely, ST6567, ST6568, ST6569, ST6570, ST6571, ST6572, and ST6573. Using risk factor analysis, we also demonstrated that long, invasive procedures used in the ICU, such as tracheal intubation and ventilator usage, along with patients with cerebral infarction and other embolism are more susceptible to developing MRSA colonization and further infections.
Conclusion: We recommend the infection control department within hospitals to actively screen for MRSA and perform risk factor analysis in order to establish accurate preventive measures for controlling MRSA spread.
Keywords: methicillin-resistant Staphylococcus aureus , MRSA, active screening, mecA, molecular epidemiology, risk factors, Panton Valentine leucocidin