How to remove 'at' from formatted date string?

This is the date formatter setup:

let dateFormatter = DateFormatter()
dateFormatter.dateStyle = .medium
dateFormatter.timeStyle = .medium

Expected output:

Aug 13, 2017 6:04:11 PM

Current output:

Aug 13, 2017 at 6:04:11 PM

How can the 'at' word be removed ideally without specifying a format string and where does it come from?

With Austrian German locale:

dateFormatter.locale = Locale(identifier: "de_AT")
13.08.2017, 18:04:11

With US English locale:

dateFormatter.locale = Locale(identifier: "en_US")
Aug 13, 2017 at 6:04:11 PM