Postscaling bacteremia in HIV-associated gingivitis and periodontitis.

Aseptic venipuncture was used to obtain samples of blood from 22 patients seropositive for human immunodeficiency virus (HIV) with gingivitis (HIV-G) and 19 HIV-seropositive patients with periodontitis (HIV-P), 15 and 30 minutes after the initiation of routine dental scaling and root planing. The presence of colony forming units in 1.2 ml aliquots of blood collected with the Isostate system (DuPont Isostat System, Doraville, Ga.) was assayed on trypticase soy blood agar. Six of the samples from HIV-G subjects were positive for colony forming units 15 minutes after scaling but not at 30 minutes. Similar evidence of bacteremia was found in seven of the HIV-P patients 15 minutes after scaling was initiated in this group, with no microbial growth detectable in samples obtained at 30 minutes. In two HIV-G and three HIV-P patients with demonstrable bacteremias a postoperative fever developed. For both HIV-G and HIV-P groups no significant difference was found between the absolute CD4 T-cell counts of nonbacteremic versus bacteremic patients (p greater than 0.05). These observations suggest that special provisions for antibiotic prophylaxis in this patient group may be unnecessary.

Phagocyte-mediated killing of Candida tropicalis.

Human peripheral monocytes (MO), neutrophils (PMN), and lymphocytes (PBL) were tested for their ability to kill Candida tropicalis. With incubation times between 30 min and 2 h, unstimulated MO and PMN, but not PBL, were efficient killers of C. tropicalis. Both leukocyte subsets were able to kill at minimum 2.5:1 effector to target ratios. Pre-incubation of MO for 24 h with interferon-gamma or tumor necrosis factor (TNF) increased their ability to kill yeast targets. TNF alone had no effect on C. tropicalis targets at concentrations up to 1000 U/ml. PBL activated for 4 d with interleukin-2 did not kill yeast targets. PMN exhibited more cytocidal efficiency per cell than MO in these assays. Direct contact of effectors and targets was required; no significant killing by PMN or MO supernatants was measured. PMN-mediated killing, but not MO killing, was inhibited by a mixture of catalase and superoxide dismutase suggesting that oxygen-dependent killing mechanisms were partially responsible for candidacidal activity.

Characterization of the mycoflora from oral mucosal surfaces of some HIV-infected patients.

Oral mucosal surfaces from 54 patients seropositive for human immunodeficiency virus (HIV) were assayed for the presence of cultivable yeasts. Oral colonization with Candida albicans, represented by 6 biotypes, was evident in 35 persons. The closely related variant, Candida stellatoidea, was found in 3 patients. Single isolates of Candida parapsilosis, Candida glabrata, Candida tropicalis, and Candida paratropicalis were also identified. One patient harbored a population of Saccharomyces cerevisiae. The susceptibilities of these 43 isolates to clotrimazole and nystatin were compared by the disk diffusion technique.

Mutational loss of susceptibility to mutacin GS-5 in Streptococcus pyogenes: surface protein in a tolerant variant.

A variant (S4340) nonsusceptible to mutacin GS-5 was previously obtained from a strain of Streptococcus pyogenes susceptible to this bacteriocin. The variant was found to adsorb as much bacteriocin as parent cells and exhibit similar susceptibility to seven antibiotics and two detergents. Electrophoretic analysis of protein dissociated from mutant cells by brief sonication revealed the presence of a 74,000-dalton polypeptide not discernible in profiles obtained from susceptible parent cells. The precise role of this tolerance-associated marker remains to be determined. The protein does not appear to be an exported product transiently associated with the cell envelope.

Mutational loss of sensitivity to mutacin GS-5 in Streptococcus pyogenes: characterization of a mutant deficient in receptor protein.

By means of a stepwise selection procedure, mutants capable of growing in the presence of relatively high multiplicities of a bacteriocin from Streptococcus mutans GS-5 were obtained from a sensitivie strain of Streptococcus pyogenes. Mutacin-neutralizing activity of cell extracts containing receptor protein was examined in one variant that adsorbed 1/6 the amount of bacteriocin adsorbed by the parent strain under conditions equivalent to "saturation." Partially purified receptor protein from both parent and mutant cells neutralized an equivalent amount of bacteriocin on a weight-to-weight basis, indicating that in vitro there was no significant difference in affinity for the mutacin between the respective receptor fractions. Cell extracts from the mutant, solubilized by treatment with trichloroacetic acid, neither neutralized mutacin activity nor interfered with receptor protein-mediated mutacin neutralization in vitro. The mutant phenotype may thus represent a cell surface density of receptor protein which results in the adsorption of sublethal amounts of mutacin. The mutant retained its sensitivity to other mutacins, e.g., those produced by strains LM-7 and BHT of S. mutans, and did not differ from wild-type cells with respect to either detergent sensitivity (sodium lauryl sulfate and Triton X-100) or to inhibition by penicillin, rifampin, bacitracin, erythromycin, and tetracycline.

Alkaline phosphatase activity in a strain of Bacterionema matruchotii.

Protein from the soluble fraction of Bacterium matruchotii cells propagated in a medium containing no added inorganic phosphate was fractionated by gel permeation chromatography. The bulk of phosphatase activity assayed at pH 8.0 was found in fractions equivalent to a molecular weight of 6 x 10(5) daltons. Substrate saturation kinetics indicate at Km of 0.75 mM for p-nitrophenylphosphate. Activity was stimulated more than two-fold by Zn++ at 1 mM, but was significantly reduced by EDTA, Ca++ and inorganic phosphate. The enzyme(s) shows negligible activity at pH below 6.0 and has a narrow optimum between 7.5 and 8.5.

Bacteriocin from Actinomyces odontolyticus with temperature-dependent killing properties.

A strain of Actinomyces odontolyticus, originally isolated from human dental plaque, produced a non-dialyzable, trypsin-sensitive substance that was bactericidal for certain strains of bifidobacteria at 42 degrees C but not at 37 degrees C. Detectable quantities of the bacteriocin were not produced in liquid media. Experimentally useful yields were obtained by extraction from pour plate cultures of producer cells. At 42 degrees C, exponential killing did not occur until indicator cells had doubled at least once. At 37 degrees C, the bacteriocin effected a transient bacteriostasis. Partially purified concentrates were obtained by diethylaminoethyl-cellulose chromatography, and such material was not inactivated by ribonuclease, deoxyribonuclease, or lipase. Pronase, trypsin, and exposure to 100 degrees C for 20 min completely abolished activity. Inhibitory activity was considerably reduced by exposure to a pH of either 3 or 11. Treatment of producer cells with curing agents did not induce a high frequency of non-bacteriocinogenic cells. The odontolyticin was adsorbed by susceptible, as well as resistant, bacteria.