Molecular genotyping of methicillin resistant and susceptible staphylococcus aureus by coagulase gene polymorphism

Abstract

Background: Methicillin-resistant Staphylococcus aureus (MRSA) which causes nosocomial infections is among the most important multi-resistant pathogens worldwide. Investigations of MRSA outbreaks in nosocomial settings often require strain-typing data to verify effectively that the isolates belong to the outbreak strain, and to discriminate similarity from unsimilarity strains. Quick and reliable typing methods are required to obtain information among MRSA isolates and to
allow faster implementation of appropriate control measures.
Objective : The aim of this study was to investigate genotyping of methicillin resistant and sensitive Staphylococcus aureus (MRSA and MSSA) in Khartoum Teaching Hospital, Sudan by using antibiotype and polymerase chain reaction-restriction fragment length polymorphism (PCRRFLP) of the coagulase gene. Methods: This is across sectional study. The samples were collected from clinical wound specimens in the wards of surgery, orthopaedic and burns at Khartoum Teaching Hospital, then processed, cultured and subsequently susceptibility test was performed using disc diffusion method. The MRSA strains were investigated by oxacillin 1[g disk diffusion method. PCR used to amplify
a sequence of the coagulase (coa) gene, and the PCR products were analyzed by PCR-RFLP using Alu1 restriction enzyme. Result: Forty eight S. aureus strains were isolated and the number of MRSA identified was 9(18.75%). All strains of MRSA and MSSA were sensitive to vancomycin, while multi-drug resistance was common among MRSA strains. PCR amplification products of coa gene were approximately at 500 bp (26/48), and 580 bp (22/48). By Alu1 restriction enzyme digestion of the PCR-amplified of coagulase gene, two distinct PCR-RFLP patterns exhibited; coaA and coaB and their fragments were approximately at 190, 310 bp and 190, 390 bp with percentages of 54.2% (26/48) and 45.8% (22/48) respectively. Conclusion: PCR-RFLP is considered an attractive tool for rapidly demonstrate the frequency of different patterns and discriminate the relatedness of isolates in different hospital wards.

Key words: Methicillin-resistant Staphylococcus aureus, coagulase gene, antibiotype, restriction
fragment length polymorphism (RFLP)