BUZZ-Australia's Navitas hits all-time low on poor outlook for enrolment growth

** Education provider Navitas Ltd's shares fall as much as 11.2 pct to all-time low

** Says government changes to visa refusal rate in U.K. impacted enrolments for second semester

** Adds Australian and U.K. colleges face challenges which are impacting enrolment growth in the short term

** Shares (Berlin: DI6.BE - news) on track for biggest percentage fall since Feb 4, 2015

** Stock top percentage loser on S&P/ASX 100 Index

(Reuters Messaging: shashwat.pradhan.thomsonreuters.com@reuters.net)