Infection and Drug Resistance (Jul 2022)

Staphylococcal Cassette Chromosome mec Typing and Multilocus Variable Number Tandem Repeat Analysis of Methicillin Resistant Staphylococcus aureus Clinical Isolates with Vancomycin Creep Phenomenon

  • Arshad F,
  • Saleem S,
  • Tahir R,
  • Jahan S,
  • Jabeen K,
  • Khawaja A,
  • Huma Z,
  • Roman M,
  • Shahzad F

Journal volume & issue
Vol. Volume 15
pp. 3927 – 3938

Abstract

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Faiqa Arshad,1 Sidrah Saleem,1 Romeeza Tahir,2 Shah Jahan,2 Kokab Jabeen,3 Aneela Khawaja,4 Zille Huma,1 Muhammad Roman,1 Faheem Shahzad2 1Department of Microbiology, University of Health Sciences, Lahore, Punjab, Pakistan; 2Department of Immunology, University of Health Sciences, Lahore, Punjab, Pakistan; 3Department of Pathology, Ammer ud Din Medical College, PGMI, Lahore, Punjab, Pakistan; 4Department of Pathology, Rahbar Medical & Dental College, Lahore, Punjab, PakistanCorrespondence: Faiqa Arshad, Department of Microbiology, University of Health Sciences, Khayaban-e-Jamia, Block D Muslim Town, Lahore, Punjab, 54600, Pakistan, Email [email protected]: The association of treatment failure and mortality with vancomycin minimum inhibitory concentration creep (MIC) is a matter of serious concern in patients with severe methicillin resistant Staphylococcus aureus (MRSA) infections. The purpose of the study was to identify and characterize staphylococcal cassette chromosome mec (SCCmec) and clonal types of MRSA strains, exhibiting the vancomycin MIC creep phenomenon.Methods: A total of 3305 S. aureus strains were isolated from various clinical samples of Lahore General Hospital, Lahore, Pakistan. MRSA strains were identified by cefoxitin resistant (≤ 21mm) followed by mecA and mecC gene genotyping. Vancomycin MIC creep was determined by E-test. Isolates having MIC values > 1.5 μg/mL were further subjected for SCCmec typing (I–V and XI) and multiple-locus variable number tandem repeat analysis (MLVA) by amplification of spa, sspA, clfA, clfB, and sdrCDE genes. A dendrogram was created based on the similarity index using bioneumerics software.Results: About 13.3% (440/3305) isolates were MRSA with 99.3% (437/440) and 0.7% (3/440) carried mecA and mecC genes, respectively. In 120 MRSA isolates, the MIC of vancomycin was > 1.5μg/mL. In MRSA isolates with high vancomycin MIC (> 1.5μg/mL), the most common SCCmec type was SCCmec III (38.3%), followed by SCCmec IVa (15.8%), SCCmec IIIa (13.3%,), SCCmec IVc (7.5%), SCCmec IVe (5.8%), SCCmec IVd (5.8%), SCCmec IVb (4.2%), SCCmec II (2.5%), SCCmec V (1.7%), SCCmec I (1.7%) and SCCmec XI (1.7%). MLVA revealed 60 genotypic groups of MRSA isolates having a 92% similarity index.Conclusion: SCCmec III was the most common type in genetically related MRSA isolates showing vancomycin MIC creep. The presence of SCCmec XI may further add burden to infection control measures.Keywords: methicillin resistant Staphylococcus aureus, staphylococcal chromosomal cassette, multilocus variable number tandem repeat analysis

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