Isolation and Molecular Identification of Vancomycin Resistant and Methicillin Resistant Staphylococus aureus from Patients with Different Clinical Manifestations in Khartoum State

Abstract

Emergence of Mecthicillin resistance Staphylococcus aureus is of public health concern contributing to increase morbidity and mortality among infected patients The present study is aimed to determine the prevalence and molecular detection of MRSA, VISA and VRSA among patients in Khartoum state. The enrolled study population (n=426) were patients who attended the main Khartoum Hospitals (Military Hospital, Alrebat University Hospital, Khartoum Teaching Hospital and Khartoum North Teaching Hospital) in Khartoum State, Sudan extending from April 2010 to May 2011. The study subjects involved 211 males and 215 females with different age categories. Enrolled subjects were suffering from wound infections (105), ear infections (121), Urinary tract infections (UTI) (100), in addition to nasal discharge of medical staff (100). Clinical samples were cultured on blood agar and MacConkey agar. Cystine lysine electrolyte deficiency (CLED) agar was also used for urine samples. Gram staining and other biochemical tests were also performed for conventional identification. The results confirmed the existence of Staph. aureus in 49/426 (11.5%) cases among which MRSA were isolated from 34/49 (69.4%) when modified Kirbry-Bauer disk diffusion method was applied. Ten out of these 34 MRSA were confirmed as VRSA by culturing on BHI agar containing 6μg/ml vancomycin according to National Control Culture Standard (NCCLS) criteria. DNA was extracted from the 34 MRSA isolates (including the 10 VRSA) by phenol- chloroform method. PCR was then performed to amplify of arcC, mecA, VanA and VanB genes. Out of the 34 MRSA isolates DNA, 26 were mecA positive (76.5%) while 8 (23.5%) were arcC positive. But, vanA and B genes where not amplified In conclusion, genotype analysis confirmed the existence of MRSA among Sudanese But the same procedure failed to prove the occurrence of VRSA a mediated resistance indicating that among Sudanese isolates VRSA may be attributed to other factors.