Background Respiratory tract infection is leading causes of death among patients infected with human immunodeficiency virus in Vietnam. Identification the agents caused RTIs is very important to give specific treatment and to reduce mortality rate among HIV/AIDS patients suffering from RTI.

Methods We conducted a cross-sectional study of 170 HIV/AIDS patients with signs and symptoms (clinical manifestations and/or broncho aveolar lesions through X-ray chest film) of respiratory tract to indentify the common agents by analysing bronchoaveolarlavage (BAL).

Results A total of 170 HIV/AIDS patients (138 male and 32 female) involved in the study and 170 BAL samples had been taken to identify the common agents caused RTIs. 148/170 (87.1%) patients had been diagnosed RTIs with following agents: Mycobacterium tuberculosis 79/148 (53.4%), PJP 12/148 (8.1%), bacteria 59/148 (39.9%), fungi 54/148 (36.5%) and CMV 2/148 (1.4%). 52/148 (35.1%) patients had been isolated 2 differential agents at a moment. Most patients have very low CD4+ count (80.4% ≤ 100cells/mm3; mean = 74.6; SD = 118.7; median = 22). The more common bacteria are: Pseudomonas (P.aeruginosa, P.putida, P.pneumotropica) 15/59 (25.4%), Streptococcus (S.pneumoniae, S.pyogene) 11/59 (18.6%), Acinobacter (Aci.baumani, Aci.juni, Aci.minimus) 6/59 (10.2%), E.coli 3/59 (5.1%) and S.aureus 3/59 (5.1%). Other include: H.influenza 2/59 and each following spp have 1: Achromobacter xylosoxidans, K.pneumoniae, Enterobacter clocae, Moraxella catarhalis, and Rhodococcus equi. Isolated fungal spp include: Candida albicans 32/54 (59.2%), Penicillium marneffei 14/54 (25.9%), Aspergilus spp 4 (7.4%), Candida spp 3/54 (5.6%) and Cryptococcus neoformans 1/54 (1.9%). The common complex infections are MTB-Fungi (16 patients), MTB-Bacteria (14 patients) and Bacteria-Fungi (11patients).

Conclusion Mycobacterium tuberculosis, bacteria (P.aeruginosa, P.putida, P.pneumotropica, S.pneumoniae, S.pyogene, and Aci.baumani) and fungi (Candida albicans and Penicillium marneffei) are the more common in HIV/AIDS patients who have RTIs. Because of advanced immune depression, patients may have complex infections in a moment.