A double-blind, placebo-controlled study of Mycobacterium-specific human immune responses induced by intradermal bacille Calmette-Guérin vaccination

Recent studies have indicated that type 1 T cell responses (potent interferon-gamma and cytolytic responses, with absence of interleukin-4 production) are important for protective immunity against mycobacteria. These observations suggest that assays of type 1 T cell responses may be useful as surrogate markers of protective immunity in the evaluation of new tuberculosis vaccines. To be useful as surrogate markers, immunologic assays must distinguish between vaccine recipients and control subjects in clinical trials. Previous studies have shown that bacille Calmette-Guérin (BCG) vaccination can induce human type 1 T cell responses, but randomized trials have not been done to determine whether measurement of these responses can distinguish between BCG recipients and control subjects. We have conducted a double-blind, placebo-controlled trial of intradermal vaccination with two different BCG strains. We compared the mean lymphoproliferative, cytotoxic, Th1 and Th2 cytokine, and antibody responses detected in BCG and placebo recipients. These studies demonstrated that significant increases in Mycobacterium-specific T cell proliferative responses and type 1 cytokine responses were induced by BCG when compared with results with a placebo. In addition, BCG induced significant increases in Mycobacterium-specific antibody responses with an isotype profile characteristic of a type 1 cytokine bias. T cell and antibody assays involving the use of mycobacterial whole cell lysates or live BCG were able to discriminate between BCG and placebo recipients better than were assays using mycobacterial culture filtrates. These studies provide important information for the development of immunologic assays that might be useful as surrogate markers of protective immunity in future trials of new tuberculosis vaccines.

Intrathoracic Mycobacterium avium complex infection in immunocompetent children: case report and review

Mycobacterium avium complex (MAC) infection is a rarely recognized cause of intrathoracic infection in immunocompetent children. The incidence of this disease is unknown but is likely underestimated among children in whom MAC infection is not usually considered. An increase in the number of cases of MAC infection in adults has been noted since the late 1970s. The number of these cases in children with AIDS has also increased. There are currently no guidelines for the treatment of these children. We describe a previously healthy 14-month-old boy with a mediastinal mass for whom tuberculosis was initially diagnosed; subsequently, biopsy-proven infection with MAC was demonstrated. He received no specific therapy after surgical excision of his intrathoracic mass and has done well since. We reviewed eight additional cases of intrathoracic nontuberculous mycobacteria infection in children that were reported from 1979 to 1994 and found excellent outcomes for seven immunocompetent children who received diverse methods of treatment.

Tuberculous and foreign-body granulomatous reactions involving a total knee prosthesis

This case report describes loosening of a right knee prosthesis and represents the first report of the simultaneous occurrence of 2 granulomatous processes involving a prosthetic joint. Microscopic examination of the tissue revealed areas of foreign-body granulomas and areas of necrotizing granulomas and caseation. Acid-fast bacilli cultures were positive for Mycobacterium tuberculosis. The pathophysiology of implant loosening following an inflammatory reaction to components of prosthetic materials is discussed. Also discussed is the occurrence of infectious complications and rarity of tuberculous infections associated with prosthetic implants.

New variant of TEM-10 beta-lactamase gene produced by a clinical isolate of proteus mirabilis

A clinical isolate of Proteus mirabilis was found to produce a new variant of the TEM-10 beta-lactamase gene. This is the first report of TEM-10 production by P. mirabilis and the first report of extended-spectrum beta-lactamase production by an isolate of this species recovered in the United States.

Tailoring aortoplasty for repair of fusiform ascending aortic aneurysms

To evaluate the effectiveness of tailoring aortoplasty used to treat fusiform aneurysms of the ascending aorta, we reviewed the results of operation in 17 patients. Nine patients had tailoring aortoplasty alone, and 8 patients had aortoplasty with Dacron wrap of the ascending aorta. Fourteen of 17 patients were discharged from the hospital, and 12 patients were alive at follow-up between 2 and 120 months. Of two late deaths, neither was due to aneurysmal disease. Actuarial survival at 1 and 10 years was 81% and 63%, respectively. In selected cases, tailoring aortoplasty can achieve long-term results comparable with those of resection and graft replacement of fusiform ascending aortic aneurysms.

Antibacterial activity of hydrogen peroxide and the lactoperoxidase-hydrogen peroxide-thiocyanate system against oral streptococci

In secreted fluids, the enzyme lactoperoxidase (LP) catalyzes the oxidation of thiocyanate ion (SCN-) by hydrogen peroxide (H2O2), producing the weak oxidizing agent hypothiocyanite (OSCN-), which has bacteriostatic activity. However, H2O2 has antibacterial activity in the absence of LP and thiocyanate (SCN-). Therefore, LP may increase antibacterial activity by using H2O2 to produce a more effective inhibitor of bacterial metabolism and growth, or LP may protect bacteria against the toxicity of H2O2 by converting H2O2 to a less-potent oxidizing agent. To clarify the role of LP, the antibacterial activities of H2O2 and the LP-H2O2-SCN- system were compared by measuring loss of viability and inhibition of bacterial metabolism and growth. The relative toxicity of H2O2 and the LP system to oral streptococci was found to depend on the length of time that the bacteria were exposed to the agents. During incubations of up to 4 h, the LP system was from 10 to 500 times more effective than H2O2 as an inhibitor of glucose metabolism, lactic acid production, and growth. However, if no more H2O2 was added, the concentration of the inhibitor OSCN- fell because of slow decomposition of OSCN-, and when OSCN- fell below 0.01 mM, the bacteria resumed metabolism and growth. In contrast, the activity of H2O2 increased with time. H2O2 persisted in the medium for long periods of time because H2O2 reacted slowly with the bacteria and streptococci lack the enzyme catalase, which converts H2O2 to oxygen and water. After 24 h of exposure, H2O2 was as effective as the LP system as an inhibitor of metabolism. H2O2 also caused a time-dependent loss of viability, whereas the LP system had little bactericidal activity. The concentration of H2O2 required to kill half the bacteria within 15 s was 1.8 M (6%) but fell to 0.3 M (1%) at 2 min, to 10 mM (0.03%) at 1 h, and to 0.2 mM (0.0007%) with a 24-h exposure. The results indicate that if high levels of H2O2 can be sustained for long periods of time, H2O2 is an effective bactericidal agent, and the presence of LP and SCN- protects streptococci against killing by H2O2. Nevertheless, the combination of LP, H2O2, and SCN- is much more effective than H2O2 alone as an inhibitor of bacterial metabolism and growth.

Delayed treatment of pulmonary blastomycosis causing vertebral osteomyelitis, paraspinal abscess, and spinal cord compression

A 36-year-old woman with gallbladder disease had an incidental finding of asymptomatic cavitary lung infection with Blastomyces dermatitidis. No treatment was given initially, and 2 months later she presented with vertebral osteomyelitis, paraspinal abscess, and spinal cord compression due to dissemination of the fungus. The patient recovered following surgical debridement and treatment with 1 g of amphotericin B, followed by itraconazole 400 mg QD for 6 months. In spite of previous reports of the self limiting nature of primary pulmonary blastomycosis in the normal host, antifungal therapy may be needed in cases that do not resolve spontaneously within a short period of time, or if transient immunosuppression may be anticipated as may occur following surgery or after acquisition of other infections.

In vitro activity of clarithromycin, cefprozil, and other common oral antimicrobial agents against gram-positive and gram-negative pathogens

Macrolide and beta-lactam antimicrobial agents are frequently used for the treatment of upper and lower respiratory tract infections and skin or skin structure infections. To evaluate the relative in vitro activity of these antimicrobial drugs against organisms commonly involved in these infections, we tested clarithromycin, erythromycin, cefprozil, cefuroxime, cefaclor, cephalexin, amoxicillin, amoxicillin/clavulanate, and doxycycline against 174 gram-positive and gram-negative clinical isolates, including Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pneumoniae, group A beta-hemolytic streptococci, alpha-hemolytic streptococci, Escherichia coli, and Klebsiella pneumoniae. Manual broth microdilution susceptibility testing was used with a standard inoculum of 5 x 10(4) colony-forming units/well at pH of 7.2. Clarithromycin was the most active agent against streptococci. Methicillin-susceptible S aureus exhibited resistance to both clarithromycin and erythromycin, but was susceptible to cefprozil, cefuroxime, amoxicillin/clavulanate, and doxycycline. Cefprozil was at least as active as cefuroxime, cefaclor, and cephalexin against all organisms tested, but was fourfold less active than doxycycline against E coli and 16-fold less active than clarithromycin versus S pneumoniae. The gram-negative isolates tested showed resistance to clarithromycin and erythromycin; however, cefprozil was as active as amoxicillin/clavulanate against K pneumoniae and E coli. These results demonstrate that clarithromycin provides superior in vitro activity against common streptococci, while cefprozil, cefuroxime, amoxicillin/clavulanate, and doxycycline provide greater activity against methicillin-susceptible S aureus, K pneumoniae, and E coli. Prospective clinical trials are needed to determine the clinical significance of these findings.

Anaerobic endocarditis caused by Staphylococcus saccharolyticus

The first case of infective endocarditis caused by the anaerobe Staphylococcus saccharolyticus is reported. The infection occurred in a previously healthy 61-year-old male with no known predisposing valvular heart disease. The patient was successfully treated with a combination of 2 g of nafcillin every 4 h and 90 mg of gentamicin every 8 h for 6 weeks.

Correlation between the production of extracellular substances by type III group B streptococcal strains and virulence in a mouse model

Twelve strains of serotype III group B streptococci (8 isolated from cases of neonatal disease, 3 isolated from asymptomatically colonized infants, and 1 laboratory reference strain) were examined for the vitro production of three potential extracellular virulence products: type-specific antigen, neuraminidase, and protease. In addition, virulence in a mouse model, expressed as 50% lethal dose, was determined for the 12 strains to determine whether a relationship existed between the production of any of the three extracellular products and virulence. Only production of extracellular type-specific antigen showed a correlation with virulence in the mouse model. The high producers of extracellular type-specific antigen were an average of 166-fold more virulent for mice than low producers of the same component. There was no correlation between virulence and either neuraminidase or protease production, nor was there a correlation between either of these two extracellular products and the levels of extracellular type-specific antigen. When levels of group B streptococci of each type (a high and low producer of extracellular type-specific antigen) in organs of infected mice were examined, comparable levels of organisms were found in the brain, spleen, and lungs of mice near death regardless of the initial inoculum. However, the high producer of extracellular type-specific antigen caused death in mice with a 2 to 3 log lower inoculum than the low producer, suggesting that these strains may be more invasive.

Purification and partial characterization of neuraminidase from type III group B streptococci

Extracellular neuraminidase from a type III fresh clinical isolate of a group B streptococcus was purified by a combination of salt fractionation, affinity chromatography of Affi-Gel blue, ion-exchange chromatography on diethylaminoethylcellulose, and gel filtration on Sephacryl S-200. These procedures yielded enzyme which was purified approximately 1,000-fold compared with the enzyme found in the original supernatant fluid. This type III streptococcal neuraminidase had a molecular weight of approximately 125,000 as estimated by filtration on Sephacryl S-200 and approximately 106,000 when analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. In contrast to the majority of other bacterial neuraminidases, the type III group B streptococcal enzyme had no effect on colominic acid or N-acetylneuramin-lactose; however, it was quite active on bovine submaxillary mucin.

Extracellular neuraminidase production by clinical isolates of group B streptococci from infected neonates

A total of 73 clinical isolates of group B streptococci obtained from diseased infants in 23 states and Puerto Rico were examined for extracellular neuraminidase production. The association of elevated levels of neuraminidase with serotype III isolates was evident in a broad geographical distribution.

Protease production by clinical isolates of type III group B streptococci

Six strains of serotype III group B streptococci isolated from confirmed cases of neonatal disease were examined for their ability to produce proteolytic enzymes. Three neuraminidase-producing strains and three non-neuraminidase-producing strains were employed in this study. Protease production was examined in 1,000-fold concentrated filtrates of stationary-phase cells with an insoluble substrate derived from horse hide powder labeled covalently with Remazol brilliant blue. Protease activity was not detected in any cultural supernatant fluids until they were fractionated on Sephadex G-100. After fractionation, the neuraminidase-producing strains were shown to elaborate approximately sixfold more protease than the non-neuraminidase-producing strains. The finding that clinical isolates of group B streptococci that elaborated high levels of neuraminidase also produced elevated levels of extracellular protease may indicate that the production of several different factors may determine the virulence of these organisms.

Effect on antibiotics on protease production by a viridans streptococcus

A viridans streptococcus (Streptococcus MG intermedius 974) isolated from a confirmed case of subacute bacterial endocarditis was studied for the production of extracellular proteases during exponential growth and after penicillin (0.10 mug/ml) and/or streptomycin (20 mug/ml) treatment. Exponentially growing cultures produced a variety of extracellular proteases, as determined by the elution profiles of active proteins from Sephadex G-100 and Sepharose 4B columns. Examination of supernatant fluids from cultures of S. MG intermedius treated with penicillin or streptomycin for 12 h indicated a reduction of at least 50% in the number of different proteolytic species produced. However, some of the proteases produced by the cultures during penicillin or streptomycin treatment had significantly higher specific activities when compared with proteases produced by exponentially growing cells. The combination of penicillin and streptomycin further reduced both the number and the specific activities of the extracellular proteases on a cell dry weight basis.

Association of elevated levels of extracellular neuraminidase with clinical isolates of type III group B streptococci

The level of total extracellular neuraminidase produced by 74 clinical isolates of group B streptococci isolated from diseased or asymptomatically colonized infants was assayed. Extracellular neuraminidase was obtained from concentrated filtrates of exponentially growing cultures of group B streptococci grown in a chemically defined medium (FMC) containing supplemental protein. The total activity of extracellular enzyme produced by these clinical isolates ranged from less than 10 to 360 nmol of sialic acid released per min per mg of cell dry weight. Strains were arbitrarily classified as either nonproducers (less than 10 nmol/min per mg of cell dry weight), low producers (greater than 10 to less than or equal 140 nmol/min per mg of cell dry weight), or high producers (greater than 140 to 360 nmol/min per mg of cell dry weight). Type III isolates from diseased infants were significantly more often classified as high producers than strains of group B streptococci of other serotypes from diseased infants (P less than 0.001). Furthermore, the serotype III strains isolated from neonatal infections were more often high producers than those of the same serotype from asymptomatically colonized infants (P less than 0.025). These results suggest that the ability to produce elevated levels of neuraminidase may be related to the frequent association of type III strains with disease among neonates.

Growth and amino acid requirements of various strains of group B streptococci

A chemically defined medium (FMC; B. Terleckyj, N. P. Willett, and G. D. Shockman, Infect. Immun. 11:649-655, 1975) was used to compare the growth and amino acid requirements of 16 strains of group B streptococci, consisting of both laboratory-passaged organisms and fresh clinical isolates from adult and neonatal infections. The 5 standard Lancefield immunizing strains of group B streptococci, 090 (Ia), H36B (Ib), A909 (Ic), 18RS21 (II), and D136C (III), had doubling times in FMC (28 to 36 min) similar to those observed in Todd-Hewitt glucose broth (24 to 30 min). Similar doubling times were obtained with 11 clinical isolates growing in Todd-Hewitt glucose broth and FMC. The optimum buffering capacity of FMC was provided by 0.06 M sodium phosphate, and 1% glucose gave maximum cell yield. The group B streptococci, with minor exceptions, were very homogeneous in their amino acid requirements under both aerobic and anaerobic growth conditions. Phenylalanine, tyrosine, tryptophan, glutamate, arginine, valine, leucine, lysine, methionine, isoleucine, cystine, and histidine were required by all 16 strains under both aerobic and anaerobic growth conditions. In addition, threonine was required by all strains under aerobic growth conditions, whereas only 9 strains required threonine under anaerobic conditions. Serine was required by only 3 type III fresh clinical isolates aerobically, but not anaerobically. A requirement for glycine varied from strain to strain, apparently influenced by the oxidation-reduction potential of the growth medium.

Extracellular neuraminidase production by group B streptococci

Neuraminidase (sialidase) activity in concentrated culture filtrates of group B streptococci was measured with bovine submaxillary mucin as substrate. Group B streptococcal neuraminidase was not active on human alpha-1 acid glycoprotein and did not show increased activity on bovine submaxillary mucin that had been O-deacetylated by alkaline treatment. The enzyme was produced in a variety of media, including a chemically defined medium (FMC; Terleckyj et al., Infect. Immun. 11:649-655, 1975) supplemented with bovine serum albumin or human serum albumin. Maximal levels of activity were present in filtrates from cells grown in a dialyzable fraction of Todd-Hewitt broth harvested during the late exponential phase of growth. Dramatic decreases were seen when filtrates from the late stationary phase were assayed. The decrease in specific activity during the stationary phase was shown to be due to proteolytic digestion of neuraminidase and not to the elaboration of an extracellular neuraminic acid aldolase.

Production of extracellular material by streptococci associated with subacute bacterial endocarditis

Six strains of viridans streptococci isolated from confirmed cases of subacute bacterial endocarditis were studied for production of extracellular material. All six strains, when grown to the exponential phase, produced exoproducts that had similar elution profiles on a G-100 Sephadex column. Since essential nutrients, such as amino acids, may be periodically growth limiting to streptococci in the fibrin-covered lesions on heart valves, the potential to elaborate extracellular protein and other material by streptococci that were deprived of essential amino acids was studied. Examination of supernatant fluids from cultures of Streptococcus MG intermedius deprived of glutamate and cystine revealed the presence of a complex mixture of extracellular materials in amounts comparable to those produced by normallly growing cells, Although only a slight (21 to 24%) increase in total protein occurred during amino acid deprivation of 12 h, the extracellular material contained numerous protein components, several of which demonstrated proteolytic activity. On a cell dry weight basis, the amino acid-deprived cells produced four-to eightfold more protease(s) than did exponential cells grown in complete medium. These results demonstrate that viridans streptococci are capable of elaborating potentially damaging compounds even when their multiplication has been arrested by nutritional deprivation.

Quantitation of the tetramethyl-p-phenylenediamine oxidase reaction in Neisseria species

The tetramethyl-p-phenylenediamine oxidase reaction commonly used in the Kovacs oxidase test was quantitatively estimated for various Neisseria species employing standardized resting cell suspensions. This genus of microorganisms exhibited very high tetramethyl-p-phenylenediamine oxidase rates comparable to that of Azotobacter and Pseudomonas, and this reaction was found to be a valid measurement for the respiratory capability possessed by this group of organisms.

Preliminary characterization studies on the Neisseria catarrhalis respiratory electron transport chain

The Neisseria catarrhalis respiratory electron transport system was examined in a sonic type particulate membrane fraction and shown to have a moderately active succinate as well as nonpyridine nucleotide-dependent dl-lactate oxidoreductase and a very active tetramethyl-p-phenylenediamine oxidase. l-Malate and l-glutamate oxidation were found to be dependent on pyridine nucleotides and exclusively associated with a soluble (or nonmembranous) fraction. The primary cytochrome components in the electron transport system appear to be c-type in nature (555 nm and 550 nm) as well as cytochrome a(1) (600 nm) and cytochrome o.