Abstract
To distinguish Methicillin-Resistant Staphylococcus aureus (MRSA) from Methicillin-Sensitive Staphylococcus aureus (MSSA) in the protein sequences level, test the susceptibility to antibiotic of all Staphylococcus aureus isolates from Quanzhou hospitals, define the virulence factor and molecular characteristics of the MRSA isolates. MRSA and MSSA Pfam protein sequences were used to extract feature vectors of 188D, n-gram and 400D. Weka software was applied to classify the two Staphylococcus aureus and performance effect was evaluated. Antibiotic susceptibility testing of the 81 Staphylococcus aureus was performed by the Mérieux Microbial Analysis Instrument. The 65 MRSA isolates were characterized by Panton-Valentine leukocidin (PVL), X polymorphic region of Protein A (spa), multilocus sequence typing test (MLST), staphylococcus chromosomal cassette mec (SCCmec) typing. After comparing the results of Weka six classifiers, the highest correctly classified rates were 91.94, 70.16, and 62.90% from 188D, n-gram and 400D, respectively. Antimicrobial susceptibility test of the 81 Staphylococcus aureus: Penicillin-resistant rate was 100%. No resistance to teicoplanin, linezolid, and vancomycin. The resistance rate of the MRSA isolates to clindamycin, erythromycin and tetracycline was higher than that of the MSSAs. Among the 65 MRSA isolates, the positive rate of PVL gene was 47.7% (31/65). Seventeen sequence types (STs) were identified among the 65 isolates, and ST59 was the most prevalent. SCCmec type III and IV were observed at 24.6 and 72.3%, respectively. Two isolates did not be typed. Twenty-one spa types were identified, spa t437 (34/65, 52.3%) was the most predominant type. MRSA major clone type of molecular typing was CC59-ST59-spa t437-IV (28/65, 43.1%). Overall, 188D feature vectors can be applied to successfully distinguish MRSA from MSSA. In Quanzhou, the detection rate of PVL virulence factor was high, suggesting a high pathogenic risk of MRSA infection. The cross-infection of CA-MRSA and HA-MRSA was presented, the molecular characteristics were increasingly blurred, HA-MRSA with typical CA-MRSA molecular characteristics has become an important cause of healthcare-related infections. CC59-ST59-spa t437-IV was the main clone type in Quanzhou, which was rare in other parts of mainland China.
Highlights
Staphylococcus aureus has been considered the mainly pathogen that cause skin and soft-tissue infections, central nervous system infections, necrotizing pneumonia and infections associated with intravascular devices (Conceicao et al, 2007; Nadig et al, 2010; Rosa et al, 2016)
Comparing the antibiotic resistance rate between CC59-ST59-spa t437-IV clone and other types, this study found that the resistance rate of CC59-ST59-spa t437-IV clone to CIP, CN and RD was lower than other clone types (p < 0.05) (Table 2)
It is reported that methicillin-resistant Staphylococcus aureus (MRSA) has reached over 60% of all isolated Staphylococcus aureus and the incidence of MRAS has increased to 49% in the United States (Jiang et al, 2020)
Summary
Staphylococcus aureus has been considered the mainly pathogen that cause skin and soft-tissue infections, central nervous system infections, necrotizing pneumonia and infections associated with intravascular devices (Conceicao et al, 2007; Nadig et al, 2010; Rosa et al, 2016). Which is based on the well-known differences of the mecA gene conferred to the pathogen, and the significant difference of the biofilm formation between MRSA and MSSA strains (Gidari et al, 2020). MRSA is responsible for most global Staphylococcus aureus bacteremia cases, and MRSA infection is related to poorer clinical outcomes than MSSA (Hassoun et al, 2017). MRSA is an important nosocomial pathogen that is being observed with increasing frequency in community settings. MRSA and MSSA may owe the tst gene as an aid to targeted infection control (Schlebusch et al, 2009). Machine learning algorithm was performed to accomplish the classification of MRSA and MSSA based on their protein sequences (Liao et al, 2018b)
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