1 Department of Infection Prevention & Control, Ministry of National Guard Health Affairs, Riyadh, Saudi Arabia; King Abdullah International Medical Research Center, Riyadh, Saudi Arabia; King Saud bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia. Electronic address: liaquathej@yahoo.com.
2 Karachi Medical and Dental College, Karachi, Pakistan.
3 King Abdullah International Medical Research Center, Riyadh, Saudi Arabia.