Carriage of Staphylococcus aureus among Hajj pilgrims.

OBJECTIVE: To evaluate the prevalence of methicillin resistant Staphylococcus aureus (MRSA) carriage among a cohort of pilgrims during 2004 Hajj season. METHODS: Pilgrims attending the 2004 Hajj season were recruited and screened for carriage of MRSA. Standard microbiological techniques were used to screen for the presence of MRSA. RESULTS: Out of 411 individuals screened, 85 (20.6%) were positive for Staphylococcus aureus (S. aureus) of which only 6 (1.46 %) were MRSA. Four individuals (4.6%) had the S. aureus organism in both nasal and axillary swabs, while 7 individuals (8%) had the organism in their axillae only. The other 74 individuals (87.1%) had the organism in their nares only. The 6 MRSA isolates were positive for the mecA gene by polymerase chain reaction method. None of the pilgrims examined had any risk factors for community-acquired methicillin resistant S. aureus (CAMRSA). Overall, the prevalence of MRSA in the population of pilgrims examined was found to be low (1.46%) in comparison with most community based studies. CONCLUSION: A low rate of MRSA carriage was noticed among the screened cohort. Physicians treating patients suspected of S. aureus infection during the Hajj pilgrimage should bear in mind the possibility of community acquired - MRSA and should obtain appropriate samples for bacterial cultures and susceptibility testing so that antimicrobial agents could be introduced when necessary at a later stage.

Evaluation of 2 real-time PCR assays for the investigation of mecA gene in clinical isolates of MRSA in Western Saudi Arabia.

OBJECTIVE: In diagnostic microbiology laboratories, Methicillin resistant Staphylococcus aureus (MRSA) is identified by positive coagulase test and positive deoxyribonuclease (DNase) activity followed by demonstration of oxacillin resistance on susceptibility testing on agar plate. This usually takes an approximately 48-72 hours. The purpose of this study is to evaluate 2 real-time polymerase chain reaction (PCR) assays for the presence of mecA gene in a population of MRSA strains circulating in Jeddah, Western Saudi Arabia, in order to determine their usefulness in the speedy diagnosis of MRSA in our clinical setting and their contribution to optimal patient management. METHODS: Ninety MRSA isolates obtained from clinical samples were identified by using conventional methods. They were collected between February 2004 and August 2004, from 2 major hospitals in Jeddah; King Abdul-Aziz University Hospital, Jeddah (50 strains) and King Khalid National Guard Hospital, Jeddah (40 strains). All isolates were confirmed as MRSA using Gram stain, catalase and coagulase activity, confirmatory DNAse activity and Kirby Bauer disc diffusion method with resistance to oxacillin by the agar disc method. The DNA extract was tested by 2 assays. The first was the commercial IVD Roche kit, which detects the mecA gene using the Light Cycler system. The other method employs multiplex PCR which detects As442 fragment and mecA optimized for the Smart Cycler system (Cephied). The length of time taken to perform the assays was recorded. RESULTS: All isolates were positive for Sa442 fragment and the coa gene specific for Staphylococcus aureus (S. aureus). However, 88/90 isolates (97.7%) tested were positive for mecA gene with both systems. The amplification, detection and melting curve analysis took 59.2 minutes for 32 samples on the Light Cycler and 46.7 minutes for 16 samples on the Smart Cycler. CONCLUSION: The 2 methods studied were equally specific and sensitive for the detection of mecA gene in confirmed S. aureus isolates and capable of identifying MRSA much earlier than conventional methods. The detection of 2 targets in the multiplex PCR assay reduces the 2-hour time required for DNase testing and may be used as a primary screening test for the detection of MRSA in clinical samples, such as blood cultures and sterile body fluids.