CD4 and tuberculosis: These include a high proportion of co-infections with tuberculosis (23.6%) and other bacterial pathogens (14.3%), very low median CD4 cell counts (26 cells/mm3, IQR 12 to 70), and severe impairment of oxygenation (median PaO2 6.9 kPa, IQR 5.7 to 7.9) at presentation.