[1] Univ Witwatersrand, Charlotte Maxeke Johannesburg Acad Hosp, Dept Crit Care, Johannesburg, South Africa
[2] Univ Witwatersrand, Fac Hlth Sci, Johannesburg, South Africa
[3] Univ Cape Town, Fac Hlth Sci, Dept Med Microbiol, Rondebosch, South Africa
[4] Univ Witwatersrand, Fac Hlth Sci, Dept Internal Med, Johannesburg, South Africa