JOHANNESBURG (Reuters) - South Africa's business confidence retreated further in the fourth quarter of the year, reaching its lowest in five years as activity in the retail, new vehicle trade and manufacturing sectors slowed, a survey showed on Thursday. The Rand Merchant Bank (RMB) index, which is compiled by the Bureau for Economic Research, shed two points to 36, bringing its total losses over the past year to 15 points. The latest index suggested that real GDP growth in Africa's most industrialised but ailing economy moderated further in the fourth quarter compared with the same period in 2014, RMB chief economist Ettienne Le Roux said. "In aggregate, growth of around 1 percent to 1.5 percent seems like the most probable outcome for this year, with a very similar prognosis for 2016 at this stage," Le Roux said. Growth could be lower if the current drought ravaging South Africa worsened, he added. (Reporting by Stella Mapenzauswa; Editing by James Macharia)