Abstract
Recent literature indicates that between 40-53% of AIDS patients are infected with disseminated M. avium-intracellulare (MAI) complex. In order to determine how TB and MAI have evolved at St. Vincent's Hospital during the current AIDS epidemic in which differing populations have entered into the scenario, a retrospective analysis was made between 1979-1989. The study demonstrated that the MAI:TB ratio which expresses changes in MAI and TB exposure patterns, can serve as a useful indicator of change in the composition of the AIDS population pool. The paraffin wax slide culture baiting technique or Para SL/C for viewing in situ mycobacterial cording provided a useful means for making the distinction between the serpentine cording of non-tuberculous and tuberculous cording. Twenty percent of the St. Vincent's blood isolates displayed cording. An adaptation of the Para SL/C method was developed for antimicrobial sensitivity testing. Clinical isolates of MAI were tested against ciprofloxacin, amikacin and azithromycin by Para SL/C. The procedure was reproducible with all agents tested. The plasmid profile of St. Vincent's blood derived MAI isolates showed that pLR-7 type plasmids were found in 85% of the MAI isolates obtained from St. Vincent's Hospital and Memorial Sloan-Kettering Cancer Center. By contrast, only 20% of the aforementioned isolates showed the presence of pLR-20 type plasmids. This investigation has observed that the A1 R.F.L.P. pattern occurred in 50% of the MAI isolates analyzed. R.F.L.P. patterns A/I, A2 and A3 occurred, respectively, at 12.5%, 25%, 12.5%. HeLa Cells have epithelial cell characteristics and were used to indicate MAI invasiveness. The loss of MAI cording, presence or absence of pLR-7 or the presence of both the pLR-7 and pLR-20 types plasmids appeared not to be indicative of a heightened invasiveness. The sampling of R.F.L.P. types analyzed did not permit a direct correlation between specific R.F.L.P. type and a heightened index of invasiveness.