Various methods were used to determine the in vitro susceptibility of Mycobacterium avium complex strains isolated from patients with acquired immunodeficiency syndrome. Our results confirm the noted resistance of the M. avium complex to conventional antituberculosis agents. The procedures used were both agar dilution and broth dilution, including a commercially available radiometric system (BACTEC; Johnston Laboratories, Towson, Md.). In general, all strains were more resistant by an agar dilution procedure than by a broth dilution procedure. Radiometric data were analyzed by defining a value, termed T100, which provides a discrete MIC. The broth (radiometric) procedure is reproducible and convenient for screening antimicrobial agents for in vitro activity and assessing potential therapeutic efficacy. Nevertheless, there is no standard procedure for determining the in vitro susceptibility of the M. avium complex, and appropriate clinical correlation studies are needed to accurately assess the clinical relevance of any in vitro result.Disseminated infections caused by the Mycobacterium avium complex commonly occur in patients with acquired immunodeficiency syndrome (AIDS) and are increasingly recognized as a cause of serious disease in other immunocompromised patients (7, 22; R. C. Good, Clin. Microbiol. Newsl., 1:1-4, 1979). Treatment of M. avium complex infections in patients with AIDS has been particularly frustrating. M. avium complex clinical isolates are commonly resistant to isoniazid (INH) and variably susceptible to rifamycins (RIF), ethambutol (EMB), and aminoglycosides (19; R. C. Good, V. A. Silcox, J. C. Kilburn, and B. D. Plikaytis, Clin. Microbiol. Newsl. 7:133-136, 1986). There is recent evidence that M. avium complex isolates from patients with AIDS may be more resistant to antimicrobial agents than are isolates from non-AIDS patients (10). Treatment regimens including four to six different antimycobacterial agents are often used, but there is little evidence that treatment can eradicate the infection and prolong life in these severely immunocompromised patients (2, 3). The situation is complicated not only by the lack of clearly effective therapeutic agents but by the lack of a standard method for determining the in vitro susceptibility of M. avium complex isolates to either conventional or entirely novel antimycobacterial agents. Interpretation of results determined by any in vitro method is mitigated by a lack of correlation with clinical efficacy. Our strategy was to identify a convenient and reproducible procedure for in vitro susceptibility testing of M. avium complex isolates. Such a procedure should provide a discrete MIC and a reasonably rapid result, be convenient for screening large numbers of agents, and correlate with in vivo studies of single drugs in animals and, eventually, with clinical efficacy in humans. Angeles, Los Angeles. In each case, the patient was diagnosed as having disseminated M. avium complex disease, and the sites of isolation included blood, bone marrow, lung, liv...

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A sensitive, specific, and rapid enzyme-linked immunosorbent assay has been developed for the detection of immunoglobulin G to Staphylococcus aureus teichoic acid in human sera. Detection of S. aureus teichoic acid antibody is at least 800 times more sensitive than a double diffusion in gel assay, and positive titers of 1:25,600 and greater were observed with this assay. Results with the enzyme-linked immunosorbent assay can be obtained within 3.5 h by using antigen-coated cuvettes. Quantitation of S. aureus teichoic acid antibody by this enzyme-linked immunosorbent assay may be useful in the initial as well as the follow-up diagnosis of serious S. aulreus infections.