Care worker Alec Wallbank, 30, of Pontypridd, Rhondda Cynon Taff, is alleged to have carried out the offence between July and September 2014 in Cardiff.
He appeared at Cardiff Magistrates Court wearing a black shirt and tie.
He was released on bail and the case was sent to Cardiff Crown Court.
A plea and case management hearing is due to be held on 18 August.

The visitors led 24-0 at the break through a brace from Sneyd and tries from Fetuli Talanoa and Albert Kelly.
Kelly bagged his second after the restart and Josh Griffin and Carlos Tuimavave scored before Sneyd crossed for his third of the evening.
Sam Wood and Oliver Roberts got consolation scores for the Giants in the second half.
Huddersfield stand-off Danny Brough, who needs six points to move up to ninth on the all-time domestic points scorers list, missed both his attempts at goal.
The dominant victory moves the Black and Whites up to second in the Super League table before the rest of the weekend's fixtures.
Huddersfield Giants: Mason, Ormsby, S. Wood, Mellor, McIntosh, Brough, Brierley, Rapira, Leeming, Ikahihifo, Roberts, Smith, Hinchcliffe.
Replacements: Wakeman, Clough, Dickinson, M. Wood.
Hull FC: Shaul, Fonua, Tuimavave, Griffin, Talanoa, Kelly, Sneyd, Taylor, Houghton, Bowden, Manu, Minichiello, Thompson.
Replacements: Connor, Green, Matongo, Washbrook.
Referee: Phil Bentham.
Attendance: 5,176.
A deputy manager of a mental health ward has appeared in court accused of engaging in sexual activity with a woman patient.
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Marc Sneyd scored a hat-trick and kicked eight goals as Hull FC comfortably won at Huddersfield Giants.