Genetic and phenotypic study of methicillin-resistant Staphylococcus aureus among patients and health care workers in Mansoura University Hospital, Egypt.

Background and Objectives: Staphylococcus aureus is common pathogen that is associated with many hospital acquired infections. The virulence of S. aureus is identified with resistance to antibiotics especially to methicillin. Therefore the aims of the present study were to detect the carrier rates of methicillin-resistant S. aureus (MRSA) among health care Workers (HCWs) and patients and to compare use of specific chromogenic agar for MRSA culture with PCR for detection of MRSA genes.

Materials and Methods: Samples obtained were subjected to full microbiological laboratory studies involving culture on specific chromogenic medium and antibiotics susceptibility testing for detection of MRSA and their resistance rates to other commonly used antibiotics. Furthermore multiplex PCR was carried out to detect SCCmecA genes.

Results: Staphylococcus aureus was isolated from 70 (29.9%) of the studied subjects. MRSA isolates (n=28) had high resistance rates for the used antibiotics and the most common resistance was for ciprofloxacin and chloramphenicol (57.1% for each). MRSA was isolated mainly from health care workers (17.02%). The frequency of SCC mecA was 60.7% for type I, 25% for type III and 14.3% for type II. Chromogenic agar identified correctly MRSA isolates in 92.9%. PCR was positive in all isolates with resistance to cefoxitin disc.

Conclusions: The present study highlights that MRSA carriage is common among health care workers in one Egyptian tertiary care hospital. The major genotype of MRSA is belonging to SCC mecA type I followed by type III and type II. ChromID medium is an accurrate culture method for detection of MRSA compared to molecular method.