We have investigated the efficacy of a clarithromycin-containing four-drug regimen for Mycobacterium avium complex (MAC) pulmonary disease in 46 patients without acquired immunodeficiency syndrome (AIDS). The patients were 14 males and 32 females with a mean age of 60.9 +/- 11.5 yr. Patients received 10 mg/kg/d of clarithromycin plus ethambutol, rifampin, and initial kanamycin and subsequent quinolone for 24 mo. Seven patients (15.2%) were dropped in the first 6 mo. Among 39 patients who received more than 6 mo of therapy, 28 patients (71.8%) converted their sputa to negative: 26 of 31 patients (83.9%) infected with clarithromycin-susceptible strains and two of eight patients (25.0%) with resistant or intermediate strains. The timing of sputum conversion was 3.6 +/- 1.9 mo, with a range of 2 to 9 mo. The conversion rate was significantly lower in patients who were infected with clarithromycin-resistant or intermediate strains, who had had prior therapy (55.0% versus 89.5%), or who were acid-fast bacilli (AFB) smear-positive at entry (60.7% versus 100%). The age and sex of patients, the species of pathogen (M. avium or M. intracellulare), type and extent of the disease, and the use of kanamycin did not significantly affect the conversion rate. Although the regimen was efficacious for newly treated patients, frequent adverse reactions and a low conversion rate of sputum in retreated patients are problems that remain to be solved.

No abstract

Listeriolysin O (LLO), a cholesterol-binding cytolysin of Listeria monocytogenes, exhibits cytokine-inducing and cytolytic activities. Because the cytolytic activity was abolished by cholesterol treatment but the cytokineinducing activity was not, these activities appeared to be linked to different domains of the LLO molecule. In this study, we constructed recombinant full-length LLO (rLLO529) and various truncated derivatives and examined their cytolytic, cholesterol-binding, and gamma interferon (IFN-␥)-inducing activities. rLLO529 exhibited both IFN-␥-inducing and cytolytic activities. Four truncated rLLOs possessing different C termini, which did not exert either cytolytic or cholesterol-binding activity, stimulated IFN-␥ production in normal spleen cells. However, a truncated rLLO corresponding to domain 4 (rLLO416-529) did not exhibit IFN-␥-inducing activity, whereas it did bind to immobilized cholesterol. In addition, though the hemolysis induced by rLLO529 was inhibited by rLLO416-529, such inhibition was not detected upon rLLO529-induced IFN-␥ production. These data indicated that domain 4 was responsible for binding of LLO to membrane cholesterol followed by oligomerization and pore formation by the entire LLO molecule. In contrast, the other part of LLO, corresponding to domain 1-3, was essential for IFN-␥-inducing activity. These findings implied a novel aspect of the function of LLO as a bacterial modulin.Listeria monocytogenes is a gram-positive, facultative intracellular bacterium which is responsible for sporadic but severe infections in humans and other animal species (18, 28). The major virulence factor of this bacterium essential for intracellular survival inside professional phagocytes is listeriolysin O (LLO), a pore-forming cytolysin (15). Based on the loss of escape from the phagosomal compartment into the cytosolic space of macrophages in LLO-deficient mutants, LLO is believed to lyse the phagosomal membrane and enable L. monocytogenes to gain access to the cytosol, resulting in intracellular parasitism (6,17,25).LLO has been purified from culture supernatant of L. monocytogenes as a homogenous protein of approximately 60 kDa (10,14). The gene encoding LLO, hly, has been cloned and sequenced, and the amino acid sequence of LLO has been determined (8,19). LLO is a member of the family of thiolactivated cytolysins (TACYs), including streptolysin O (SLO), pneumolysin (PLY), and perfringolysin O (PFO) (1). An important feature of the TACYs is the presence of a highly conserved undecapeptide sequence (ECTGLAWEWWR) in the C-terminal region that is believed to be essential for the hemolytic activity. Conversion of the unique cysteine residue located within the undecapeptide of SLO (24), PLY (27), and LLO (20) to alanine by site-directed mutagenesis resulted in a minor loss of activity. In addition, pyolysin, a TACY from Arcanobacterium pyogenes, is reported to contain no cysteine residue in the undecapeptide (5). In contrast, a drastic decrease in hemolytic activity was observed after replacemen...

Pneumolysin (PLY), an important virulence factor of Streptococcus pneumoniae, is known to exert various effects on the host immune cells, including cytokine induction, in addition to its known cytolytic activity as a member of the thiol-activated cytolysins. It is of interest to determine whether cytolytic activity is involved in triggering the cytokine production. In this study, we constructed full-length recombinant PLY and noncytolytic truncated PLYs with C-terminal deletions to examine the response of spleen cells to these PLY preparations. When cytolytic activity was blocked by treatment with cholesterol, full-length PLY was capable of inducing gamma interferon (IFN-␥) production. Truncated PLYs that originally exhibited no cytolytic activity were also active in IFN-␥ induction. Therefore, the IFN-␥-inducing ability of PLY appeared to be independent of the cytolytic activity. Furthermore, IFN-␥-inducing preparations were also capable of inducing nitric oxide synthase expression and nitric oxide (NO) production, and the addition of neutralizing antibody to IFN-␥ abolished the NO production. These results clearly demonstrated that PLY is capable of inducing IFN-␥ production in spleen cells by a mechanism different from pore formation and that the induced IFN-␥ stimulates NO production. These findings were discussed with reference to the contribution of PLY to the virulence of S. pneumoniae in vivo.

The introduction of an active system of IDP consultation for every case of Candida BSI in our hospital substantially improved patient outcomes.