RESUMO
Staphylococcus aureus is a major cause of nosocomial infections that uses numerous virulence factors, such as extracellular toxins and enzymes. Epidemic Methicillin-resistant S. aureus [MRSA] strains were described as multi-resistant strains with special capacity to colonize patients and staff and cause widespread outbreaks of infections. Rapid identification of MRSA from clinical specimens and screening of high risk patients for MRSA colonization have been found to be cost effective measures for limiting the spread of the organism in hospitals. The aim of this study was screening of MRSA infection in patients admitted to the Internal Medicine Department in Assiut University Hospital, using oxacillin resistance agar screen base [ORSAB] and MRSA screen test and to compare the antibiotic susceptibility pattern of MRSA infected patients with those of house-hold contacts and paramedical staff to evaluate their role in transmission of MRSA. The present study included 455 patients with nosocomial infections admitted to the ICU of Neurology and Chest Departments and the Diabetic Foot Care Unit. 154 nurses and workers in these units as well as 110 healthy volunteers who were household contacts of the patients with S. aureus infections were also included. Swabs were collected from the anterior nares of all studied groups and from the bed sores of patients who developed nosocomial beds sores. Sputum samples and endotracheal aspirates were also collected from patients who developed nosocomial pneumonia. Pus samples were collected from post-operative infected wounds of diabetic foot patients. All samples were cultured on mannitol salts agar. Colonies were identified by growth characteristics, Gram staining, biochemical reactions and confirmed by coagulase tube test. Coagulase positive mannitol-fermenting colonies were subcultured on ORSAB medium then subjected to MRSA screen test to detect PBP2a. Sensitivity patterns of the isolated strains were detected by Kirby and Bauer technique. It was found that 24% of the patients [110/455] were infected nosocomially with S. aureus. 60 patients were infected with MRSA [55% of S. aureus infected patients and 13% of the whole patients]. MRSA nasal colonization was reported in 17.5% of the patients [80/455], 5.2% of paramedical staff [8/154] and 18% of the household contacts [20/110]. The results of antibiogram showed that MRSA strains remained sensitive to ciprofloxacin, rifampin, gentamycin and vancomycin with the highest sensitivity obtained by ciprofloxacin. MRSA strains of patients and paramedical staff had the same antibiogram type while slightly different from those of their household contacts denoting that the paramedical staff had a major role in transmission of MRSA. Regular screening of patients gives an early warning of the presence of MRSA and assess the efficiency of barrier and application of basic infection control measures [standard precautions]. Prevention is better than treatment, but for those who are already affected, control is the most likely achievable goal rather than eradication to prevent cross transmission. We recommend the use of molecular methods for accurate and rapid typing of MRSA