High frequency of SCCmec type IV and multidrug-resistant SCCmec type I among hospital acquired methicillin-resistant Staphylococcus aureus isolates in Birjand Imam Reza Hospital, Iran

The ever-increasing of antibiotic resistance in methicillin-resistant Staphylococcus aureus (MRSA) has become a major threat to public health worldwide. Molecular typing is used to determine the source of MRSA infections as well as to control and prevent the spread of these pathogens. The present study aimed to investigate the characteristics of staphylococcal cassette chromosome mec (SCCmec) types and antibiotic resistance of community- acquired (CA-) and hospital acquired (HA-) MRSA isolates.

In this cross-sectional study, the antibiotic susceptibility patterns of 109 clinical S. aureus isolates were determined by the Kirby-Bauer disk-diffusion and microdilution broth methods. MRSA isolates were confirmed using the polymerase chain reaction (PCR) method for the detection of the mecA gene. SCCmec typing was performed by a multiplex PCR assay among MRSA isolates.

The prevalence of MRSA isolates was 39.4%. Linezolid, vancomycin, and ceftaroline were the most effective agents against MRSA isolates. The incidence of multidrug-resistant (MDR) and resistance to most antibiotics were significantly higher in MRSA than methicillin-susceptible S. aureus (MSSA) isolates (P<0.05). SCCmec types I, III, and IV were identified in 27.9%, 23.3%, and 37.2% of MRSA isolates, respectively. SCCmec type I and IV were the most prevalent SCCmec types in HA-MRSA isolates (each was 32.4%). While SCCmec type IV (66.7%) was the most frequently SCCmec type associated with CA-MRSA isolates.

Our findings demonstrated a high rate of MDR among MRSA isolates. The high existence of SCCmec type IV was reported among the HA-MRSA isolates, which can indicate the spread of MRSA community isolates to hospital settings. Therefore, appropriate antibiotic stewardship plans and microbiological surveillance initiatives must be implemented in healthcare facilities to monitor and limit the spread of these resistant bugs.